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Sample records for intravenous digital subtraction

  1. Videodensitometric ejection fraction from intravenous digital subtraction right ventriculograms: correlation with first pass radionuclide ejection fraction

    SciTech Connect

    Detrano, R.; MacIntyre, W.; Salcedo, E.E.; O'Donnell, J.; Underwood, D.A.; Simpfendorfer, C.; Go, R.T.; Butters, K.; Withrow, S.

    1985-06-01

    Thirty-one consecutive patients undergoing intravenous blurred mask digital subtraction right ventriculography were submitted to first pass radionuclide angiography. Second order mask resubtraction of end-diastolic and end-systolic right ventricular digital image frames was executed using preinjection end-diastolic and end-systolic frames to rid the digital subtraction images of mis-registration artifact. End-diastolic and end-systolic perimeters were drawn manually by two independent observers with a light pen. Ejection fractions calculated from the integrated videodensitometric counts within these perimeters correlated well with those derived from the first pass radionuclide right ventriculogram (r = 0.84) and the interobserver correlation was acceptable (r = 0.91). Interobserver differences occurred more frequently in patients with atrial fibrillation and in those whose tricuspid valve planes were difficult to discern on the digital subtraction right ventriculograms. These results suggest that videodensitometric analysis of digital subtraction right ventriculograms is an accurate method of determining right ventricular ejection fraction and may find wide clinical applicability.

  2. Intravenous vs. left ventricular injection of ionic contrast material: hemodynamic implications for digital subtraction angiography

    SciTech Connect

    Mancini, G.B.; Ostrander, D.R.; Slutsky, R.A.; Shabetai, R.; Higgins, C.B.

    1983-03-01

    Because of the increased use of intravenous injection of contrast material for the evaluation of cardiac structure and function by digital subtraction techniques, a study was done to assess the hemodynamic effects of contrast material when used in this fashion in man. In 10 patients, with each serving as his own control, the effects of intravenous and intraventricular injections of sodium meglumine diatrizoate (Renografin 76) in the same dose were compared. There was no difference between these two methods with respect to changes in pulmonary wedge pressures, systemic pressures, and pulmonary vascular resistance. The elevation of mean pulmonary artery and right atrial pressure was greater after the intraventricular injection (p <0.05). The elevated cardiac output and systemic vascular resistance returned to control values somewhat more quickly after the intravenous injection (p<0.001 and p<0.05, respectively); and the increase in cardiac output was greater after the intravenous injection at 1 min (p<0.05), but less than after the intraventricular injection at 2 min (p<0.05). Despite the detection of these statistically significant differences, the magnitude and timing of these differences are too small to justify the notion that imaging by intravenous injections of standard ionic contrast media provides any substantial hemodynamic benefits or decreased risk to the patient.

  3. The potential for neurovascular intravenous angiography using K-edge digital subtraction angiography

    NASA Astrophysics Data System (ADS)

    Schültke, E.; Fiedler, S.; Kelly, M.; Griebel, R.; Juurlink, B.; LeDuc, G.; Estève, F.; Le Bas, J.-F.; Renier, M.; Nemoz, C.; Meguro, K.

    2005-08-01

    Background: Catheterization of small-caliber blood vessels in the central nervous system can be extremely challenging. Alternatively, intravenous (i.v.) administration of contrast agent is minimally invasive and therefore carries a much lower risk for the patient. With conventional X-ray equipment, volumes of contrast agent that could be safely administered to the patient do not allow acquisition of high-quality images after i.v. injection, because the contrast bolus is extremely diluted by passage through the heart. However, synchrotron-based digital K-edge subtraction angiography does allow acquisition of high-quality images after i.v. administration of relatively small doses of contrast agent. Materials and methods: Eight adult male New Zealand rabbits were used for our experiments. Animals were submitted to both angiography with conventional X-ray equipment and synchrotron-based digital subtraction angiography. Results: With conventional X-ray equipment, no contrast was seen in either cerebral or spinal blood vessels after i.v. injection of iodinated contrast agent. However, using K-edge digital subtraction angiography, as little as 1 ml iodinated contrast agent, when administered as i.v. bolus, yielded images of small-caliber blood vessels in the central nervous system (both brain and spinal cord). Conclusions: If it would be possible to image blood vessels of the same diameter in the central nervous system of human patients, the synchrotron-based technique could yield high-quality images at a significantly lower risk for the patient than conventional X-ray imaging. Images could be acquired where catheterization of feeding blood vessels has proven impossible.

  4. Intravenous digital subtraction angiography in the preoperative evaluation of renal masses

    SciTech Connect

    Ford, K.K.; Braun, S.D.; Miller, G.A. Jr.; Newman, G.E.; Dunnick, N.R.

    1985-08-01

    Intravenous digital subtraction angiography (DSA) was performed in 23 patients with renal masses to document tumor extension into the main renal vein or inferior vena cava. The DSA findings were compared with computed tomographic as well as surgical and pathologic findings. Additional data regarding the number of renal arteries present and the relative vascularity of the tumor were also gathered. In 17 of 19 cases, single renal arteries to the affected kidney were correctly identified. In three patients, two renal arteries to the involved kidney were correctly identified. The renal masses were avascular in two patients, hypovascular in five, moderately vascular in eight, and hypervascular in seven. In one case the mass was out of the field of view, and vascularity was not evaluated. In these patients, DSA was an accurate and relatively noninvasive method to assist in the preoperative evaluation of renal masses.

  5. How Do Videodensitometric Ejection Fractions From Intravenous Digital Subtraction Ventriculograms Compare With First Pass Radionuclide Ejection Fractions? (Technical Aspects)

    NASA Astrophysics Data System (ADS)

    Detrano, Robert; MacIntyre, William; MacIntyre, Raymond; Jones, Houston; Withrow, Susan; Simpfendorfer, Conrad; Salcedo, Ernesto E.; Lando, Anthony

    1985-06-01

    Three major errors implicit in the determination of ejection fractions from videodensi-tometric analysis of intravenous digital subtraction ventriculograms are errors due to: (1) nonlinear transfer of densitometric information about relative volumes, (2) inadequate background subtraction and (3) overlapping atrial contrast. Nonlinear errors associated with our imaging system were estimated using balloon phantoms in a water bath. These were small for a tube voltage of 90 kV and an iodine concentration of approximately 37 mg/cc commonly used in clinical studies. Background subtraction errors are approached by using phase matched second order mask images temporally close to the contrast images. Atrial overlap errors remain a significant problem. However, videodensitometric ejection frac-tions from intravenous digital studies correlated well with first pass right ventriculo-grams (r = 0.84) and left ventriculograms (r = 0.85).

  6. Digital subtraction angiography of the heart and lungs

    SciTech Connect

    Moodie, D.S.; Yiannikas, J.

    1986-01-01

    This book contains 12 chapters. Some of the chapter titles are: Physical Principles of Cardiac Digital Subtraction Angiography, The Use of Intravenous Digital Subtraction Angiography in Evaluating Patients with Complex Congenital Heart Disease, Exercise Intravenous Digital Subtraction Angiograpny, Cardiomyopathic and Cardiac Neoplastic Disease, Digital Subtraction Angiography in the Catheterization Laboratory, and Cardiac Digital Subtraction Angiography - Future Directions.

  7. Quantitative Assessment of Regional Wall Motion Abnormalities Using Dual-Energy Digital Subtraction Intravenous Ventriculography

    NASA Astrophysics Data System (ADS)

    McCollough, Cynthia H.

    Healthy portions of the left ventricle (LV) can often compensate for regional dysfunction, thereby masking regional disease when global indices of LV function are employed. Thus, quantitation of regional function provides a more useful method of assessing LV function, especially in diseases that have regional effects such as coronary artery disease. This dissertation studied the ability of a phase -matched dual-energy digital subtraction angiography (DE -DSA) technique to quantitate changes in regional LV systolic volume. The potential benefits and a theoretical description of the DE imaging technique are detailed. A correlated noise reduction algorithm is also presented which raises the signal-to-noise ratio of DE images by a factor of 2 -4. Ten open-chest dogs were instrumented with transmural ultrasonic crystals to assess regional LV function in terms of systolic normalized-wall-thickening rate (NWTR) and percent-systolic-thickening (PST). A pneumatic occluder was placed on the left-anterior-descending (LAD) coronary artery to temporarily reduce myocardial blood flow, thereby changing regional LV function in the LAD bed. DE-DSA intravenous left ventriculograms were obtained at control and four levels of graded myocardial ischemia, as determined by reductions in PST. Phase-matched images displaying changes in systolic contractile function were created by subtracting an end-systolic (ES) control image from ES images acquired at each level of myocardial ischemia. The resulting wall-motion difference signal (WMD), which represents a change in regional systolic volume between the control and ischemic states, was quantitated by videodensitometry and compared with changes in NWTR and PST. Regression analysis of 56 data points from 10 animals shows a linear relationship between WMD and both NWTR and PST: WMD = -2.46 NWTR + 13.9, r = 0.64, p < 0.001; WMD = -2.11 PST + 18.4, r = 0.54, p < 0.001. Thus, changes in regional ES LV volume between rest and ischemic states, as

  8. Pediatric digital subtraction angiography

    SciTech Connect

    Amundson, G.M.; Wesenberg, R.L.; Mueller, D.L.; Reid, R.H.

    1984-12-01

    Experience with intravenous digital subtraction angiography (DSA) in infants and children is limited, although its relative rate of performance, low complication rate, and diagnostic accuracy indicate great potential. The authors performed 87 DSA examinations (74 patients) and obtained sufficient detail to facilitate diagnosis in most cases. The major problems of patient movement and overlapping vessels can be minimized by judicious use of sedation and strict attention to technique. Exposure of patients to radiation has not been a limiting factor since our system uses low exposure factors. Our results demonstrate that DSA has wide applicability to many organ systems and is especially useful in intracranial disease and for preoperative evaluation of neoplasms.

  9. Intra-Arterial MR Perfusion Imaging of Meningiomas: Comparison to Digital Subtraction Angiography and Intravenous MR Perfusion Imaging.

    PubMed

    Lum, Mark A; Martin, Alastair J; Alexander, Matthew D; McCoy, David B; Cooke, Daniel L; Lillaney, Prasheel; Moftakhar, Parham; Amans, Matthew R; Settecase, Fabio; Nicholson, Andrew; Dowd, Christopher F; Halbach, Van V; Higashida, Randall T; McDermott, Michael W; Saloner, David; Hetts, Steven W

    2016-01-01

    To evaluate the ability of IA MR perfusion to characterize meningioma blood supply. Studies were performed in a suite comprised of an x-ray angiography unit and 1.5T MR scanner that permitted intraprocedural patient movement between the imaging modalities. Patients underwent intra-arterial (IA) and intravenous (IV) T2* dynamic susceptibility MR perfusion immediately prior to meningioma embolization. Regional tumor arterial supply was characterized by digital subtraction angiography and classified as external carotid artery (ECA) dural, internal carotid artery (ICA) dural, or pial. MR perfusion data regions of interest (ROIs) were analyzed in regions with different vascular supply to extract peak height, full-width at half-maximum (FWHM), relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and mean transit time (MTT). Linear mixed modeling was used to identify perfusion curve parameter differences for each ROI for IA and IV MR imaging techniques. IA vs. IV perfusion parameters were also directly compared for each ROI using linear mixed modeling. 18 ROIs were analyzed in 12 patients. Arterial supply was identified as ECA dural (n = 11), ICA dural (n = 4), or pial (n = 3). FWHM, rCBV, and rCBF showed statistically significant differences between ROIs for IA MR perfusion. Peak Height and FWHM showed statistically significant differences between ROIs for IV MR perfusion. RCBV and MTT were significantly lower for IA perfusion in the Dural ECA compared to IV perfusion. Relative CBF in IA MR was found to be significantly higher in the Dural ICA region and MTT significantly lower compared to IV perfusion.

  10. Intra-Arterial MR Perfusion Imaging of Meningiomas: Comparison to Digital Subtraction Angiography and Intravenous MR Perfusion Imaging

    PubMed Central

    Martin, Alastair J.; Alexander, Matthew D.; McCoy, David B.; Cooke, Daniel L.; Lillaney, Prasheel; Moftakhar, Parham; Amans, Matthew R.; Settecase, Fabio; Nicholson, Andrew; Dowd, Christopher F.; Halbach, Van V.; Higashida, Randall T.; McDermott, Michael W.; Saloner, David; Hetts, Steven W.

    2016-01-01

    Background and Purpose To evaluate the ability of IA MR perfusion to characterize meningioma blood supply. Methods Studies were performed in a suite comprised of an x-ray angiography unit and 1.5T MR scanner that permitted intraprocedural patient movement between the imaging modalities. Patients underwent intra-arterial (IA) and intravenous (IV) T2* dynamic susceptibility MR perfusion immediately prior to meningioma embolization. Regional tumor arterial supply was characterized by digital subtraction angiography and classified as external carotid artery (ECA) dural, internal carotid artery (ICA) dural, or pial. MR perfusion data regions of interest (ROIs) were analyzed in regions with different vascular supply to extract peak height, full-width at half-maximum (FWHM), relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and mean transit time (MTT). Linear mixed modeling was used to identify perfusion curve parameter differences for each ROI for IA and IV MR imaging techniques. IA vs. IV perfusion parameters were also directly compared for each ROI using linear mixed modeling. Results 18 ROIs were analyzed in 12 patients. Arterial supply was identified as ECA dural (n = 11), ICA dural (n = 4), or pial (n = 3). FWHM, rCBV, and rCBF showed statistically significant differences between ROIs for IA MR perfusion. Peak Height and FWHM showed statistically significant differences between ROIs for IV MR perfusion. RCBV and MTT were significantly lower for IA perfusion in the Dural ECA compared to IV perfusion. Relative CBF in IA MR was found to be significantly higher in the Dural ICA region and MTT significantly lower compared to IV perfusion. PMID:27802268

  11. Digital subtraction angiography of the kidney.

    PubMed

    Gattoni, F; Avogadro, A; Baldini, U; Pozzato, C; Bonfanti, M T; Gandini, D; Franch, L; Uslenghi, C

    1988-09-01

    Intravenous and intra-arterial digital subtraction angiography (DSA) was performed in 88 patients: 34 with tumours, 10 with renal trauma, 26 with suspected renovascular hypertension, 6 with vascular impression on the renal pelvis, 8 with nephrolithiasis and 4 with sonographically abnormal kidneys. Venous and arterial DSA always gave diagnostically useful images. Intravenous DSA is valuable in patients with suspected renovascular hypertension or after vascular surgery, percutaneous transluminal angioplasty and transcatheter embolisation. Arterial DSA is preferable to venous DSA in other clinical situations, particularly in the evaluation of renal tumours, and may be recommended in preference to conventional angiography.

  12. Digital subtraction angiography of the thoracic aorta

    SciTech Connect

    Grossman, L.B.; Buonocore, E.; Modic, M.T.; Meaney, T.F.

    1984-02-01

    Forty-three patients with acquired and congenital abnormalities of the thoracic aorta were studied using digital subtraction angiography (DSA) after an intravenous bolus injection of 40 ml of contrast material. Abnormalities studied included coarctation, pseudocoarctation, Marfan syndrome, cervical aorta, double aortic arch, aneurysm, dissection, and tumor. Twenty-four patients also had conventional angiography. DSA was accurate in 95% of cases; in the other 5%, involving patients with acute type I dissection, the coronary arteries could not be seen. The authors concluded that in 92% of their patients, DSA could have replaced the standard aortogram.

  13. Digital subtraction angiography in children

    SciTech Connect

    Wagner, M.L.; Singleton, E.B.; Egan, M.E.

    1983-01-01

    Preliminary results with digital subtraction angiography in infants and children have shown this to be an excellent screening procedure and often diagnostic. The examination can be performed satisfactorily on outpatients. Sixty patients have undergone this examination for evaluation of suspected abnormalities of the aortic arch and its branches, intracranial arteries, pulmonary arteries, abdominal aorta and its branches, and peripheral vessels. Adequate sedation is mandatory to prevent motion artifacts. While the literature reports increasing use of central venous catheters for delivery of contrast material, the use of short catheters placed in an antecubital vein is satisfactory for the pediatric patient. Techniques of the procedures are described along with seven appropriate case examples.

  14. Digital subtraction angiography of the portal venous system

    SciTech Connect

    Foley, W.D.; Stewart E.T.; Milbrath, J.R.; SanDretto, M.; Milde, M.

    1983-03-01

    Venous-phase arteriography after celiac or superior mesenteric artery injection is the most common technique used to demonstrate portal venous anatomy, flow direction, and portal systemic shunts. Large-volume contrast material injections and intraarterial vasodilators or balloon occlusion technique are required for optimal examinations using film-screen recording. A technique for performing venous-phase arteriography with digital subtraction imaging after celiac and superior mesenteric artery injection is described. The major advantage of intraarterial digital subtraction technique in comparison to film-screen recording is sensitivity to intravascular iodine with a consequent reduction in contrast material load and examination time. Technical success is limited only by motion artifact and should approximate the 80%-90% figure achieved for intravenous digital subtraction angiography of the aortorenal vessels.

  15. Measuring abdominal aortic aneurysms on digital subtraction arteriograms

    SciTech Connect

    Braun, S.D.; Illescas, F.F.; Fagert, T.; Dunnick, N.R.

    1985-05-01

    Digital intravenous subtraction angiography (DISA) has provided an additional method of imaging abdominal aortic aneurysms. DISA has the advantage of depicting an aneurysm in the same projection as standard arteriography but without the risks of arterial puncture and catheterization. With conventional angiography, the more constant focal spot-object-film distances both minimize magnification and reduce the variation among patients of differing size. However, with digital systems, the variations in height of the image intensifier and patient size result in wide differences in magnification. The authors have devised a simple technique to measure the size of aneurysms on digital images.

  16. Children's Use of Subtraction by Addition on Large Single-Digit Subtractions

    ERIC Educational Resources Information Center

    Peters, Greet; De Smedt, Bert; Torbeyns, Joke; Ghesquiere, Pol; Verschaffel, Lieven

    2012-01-01

    Subtractions of the type M - S = ? can be solved by various strategies, including subtraction by addition. In this study, we investigated children's use of subtraction by addition by means of reaction time analyses. We presented 106 third to sixth graders with 32 large non-tie single-digit problems in both subtraction (12 - 9 = .) and addition…

  17. Children's Use of Subtraction by Addition on Large Single-Digit Subtractions

    ERIC Educational Resources Information Center

    Peters, Greet; De Smedt, Bert; Torbeyns, Joke; Ghesquiere, Pol; Verschaffel, Lieven

    2012-01-01

    Subtractions of the type M - S = ? can be solved by various strategies, including subtraction by addition. In this study, we investigated children's use of subtraction by addition by means of reaction time analyses. We presented 106 third to sixth graders with 32 large non-tie single-digit problems in both subtraction (12 - 9 = .) and addition…

  18. Digital subtraction angiography in extremity trauma

    SciTech Connect

    Goodman, P.C.; Jeffrey, R.B. Jr.; Brant-Zawadzki, M.

    1984-10-01

    Digital subtraction angiography (DSA) may have considerable impact on the work-up of patients who have suffered trauma. The angiographic evaluation of vascular injuries can be accomplished rapidly and with minimal catheter use and manipulation, which is particularly important for those critically ill patients who have significant immobility because of multiple fractures. The authors retrospectively reviewed the digital subtraction angiograms in 50 consecutive cases of extremity trauma. The quality of the images in 44 of these permitted a confident diagnosis, the accuracy of which was confirmed by surgical or clinical follow-up. DSA reduces the time required to perform the procedure, the amount of contrast material injected, patient discomfort, and film cost. Its major disadvantage is the limited field size of the image intensifier.

  19. Digital Subtraction Angiography In Peripheral Vascular Disease

    NASA Astrophysics Data System (ADS)

    Stieghorst, Michael F.; Crummy, Andrew B.; Lieberman, Robert P.; Turnipseed, William D.; Detmer, Donald E.; Berkoff, Herbert A.

    1981-11-01

    Digital subtraction angiography (DSA) has considerable utility in the evaluation of peripheral vascular disease. It is useful in screening selected patients for vascular disease and its relative ease of performance and good patient tolerance make it ideal for serial examinations of post operative patients. When used in conjunction with intra arterial injections, the technique may show "run-off" vessels which were not demonstrated by standard angiography. This paper presents our experience using DSA to image peripheral vascular problems.

  20. Digital Subtraction Fluoroscopic System With Tandem Video Processing Units

    NASA Astrophysics Data System (ADS)

    Gould, Robert G.; Lipton, Martin J.; Mengers, Paul; Dahlberg, Roger

    1981-07-01

    A real-time digital fluoroscopic system utilizing two video processing units (Quantex) in tandem to produce continuous subtraction images of peripheral and internal vessels following intravenous contrast media injection has been inves-tigated. The first processor subtracts a mask image consisting of an exponentially weighted moving average of N1 frames (N1 = 2k where k = 0.7) from each incoming video frame, divides by N1, and outputs the resulting difference image to the second processor. The second unit continuously averages N2 incoming frames (N2 = 2k) and outputs to a video monitor and analog disc recorder. The contrast of the subtracted images can be manipulated by changing gain or by a non-linear output transform. After initial equipment adjustments, a subtraction sequence can be produced without operator interaction with the processors. Alternatively, the operator can freeze the mask and/or the subtracted output image at any time during the sequence. Raw data is preserved on a wide band video tape recorder permitting retrospective viewing of an injection sequence with different processor settings. The advantage of the tandem arrangement is that it has great flexibility in varying the duration and the time of both the mask and injection images thereby minimizing problems of registration between them. In addition, image noise is reduced by compiling video frames rather than by using a large radiation dose for a single frame, which requires a wide dynamic range video camera riot commonly available in diagnostic x-ray equipment. High quality subtraction images of arteries have been obtained in 15 anesthetized dogs using relatively low exposure rates (10-12 μR/video frame) modest volumes of contrast medium (0.5-1 ml/kg), and low injection flow rates (6-10 ml/sec). The results/ achieved so far suggest that this system has direct clinical applications.

  1. Arterial Blood Flow Measurement Using Digital Subtraction Angiography (DSA)

    NASA Astrophysics Data System (ADS)

    Swanson, David K.; Myerowitz, P. David; Van Lysel, Michael S.; Peppler, Walter W.; Fields, Barry L.; Watson, Kim M.; O'Connor, Julia

    1984-08-01

    Standard angiography demonstrates the anatomy of arterial occlusive disease but not its physiological signficance. Using intravenous digital subtraction angiography (DSA), we investigated transit-time videodensitometric techniques in measuring femoral arterial flows in dogs. These methods have been successfully applied to intraarterial DSA but not to intravenous DSA. Eight 20 kg dogs were instrumented with an electromagnetic flow probe and a balloon occluder above an imaged segment of femoral artery. 20 cc of Renografin 76 was power injected at 15 cc/sec into the right atrium. Flow in the femoral artery was varied by partial balloon occlusion or peripheral dilatation following induced ischemia resulting in 51 flow measurements varying from 15 to 270 cc/min. Three different transit-time techniques were studied: crosscorrelation, mean square error, and two leading edge methods. Correlation between videodensitometry and flowmeter measurements using these different techniques ranged from 0.78 to 0.88 with a mean square error of 29 to 37 cc/min. Blood flow information using several different transit-time techniques can be obtained with intravenous DSA.

  2. [Myocardial perfusion imaging by digital subtraction angiography].

    PubMed

    Kadowaki, H; Ishikawa, K; Ogai, T; Katori, R

    1986-03-01

    Several methods of digital subtraction angiography (DSA) were compared to determine which could better visualize regional myocardial perfusion using coronary angiography in seven patients with myocardial infarction, two with angina pectoris and five with normal coronary arteries. Satisfactory DSA was judged to be achieved if the shape of the heart on the mask film was identical to that on the live film and if both films were exactly superimposed. To obtain an identical mask film in the shape of each live film, both films were selected from the following three phases of the cardiac cycle; at the R wave of the electrocardiogram, 100 msec before the R wave, and 200 msec before the R wave. The last two were superior for obtaining mask and live films which were similar in shape, because the cardiac motion in these phases was relatively small. Using these mask and live films, DSA was performed either with the continuous image mode (CI mode) or the time interval difference mode (TID mode). The overall perfusion of contrast medium through the artery to the vein was adequately visualized using the CI mode. Passage of contrast medium through the artery, capillary and vein was visualized at each phase using TID mode. Subtracted images were displayed and photographed, and the density of the contrast medium was adequate to display contour lines as in a relief map. Using this DSA, it was found that regional perfusion of the contrast medium was not always uniform in normal subjects, depending on the typography of the coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Digital subtraction angiography: principles and pitfalls of image improvement techniques.

    PubMed

    Levin, D C; Schapiro, R M; Boxt, L M; Dunham, L; Harrington, D P; Ergun, D L

    1984-09-01

    The technology of imaging methods in digital subtraction angiography (DSA) is discussed in detail. Areas covered include function of the video camera in both interlaced and sequential scan modes, digitization by the analog-to-digital converter, logarithmic signal processing, dose rates, and acquisition of images using frame integration and pulsed-sequential techniques. Also discussed are various methods of improving image content and quality by both hardware and software modifications. These include the development of larger image intensifiers, larger matrices, video camera improvements, reregistration, hybrid subtraction, matched filtering, recursive filtering, DSA tomography, and edge enhancement.

  4. Parametric color coding of digital subtraction angiography.

    PubMed

    Strother, C M; Bender, F; Deuerling-Zheng, Y; Royalty, K; Pulfer, K A; Baumgart, J; Zellerhoff, M; Aagaard-Kienitz, B; Niemann, D B; Lindstrom, M L

    2010-05-01

    Color has been shown to facilitate both visual search and recognition tasks. It was our purpose to examine the impact of a color-coding algorithm on the interpretation of 2D-DSA acquisitions by experienced and inexperienced observers. Twenty-six 2D-DSA acquisitions obtained as part of routine clinical care from subjects with a variety of cerebrovascular disease processes were selected from an internal data base so as to include a variety of disease states (aneurysms, AVMs, fistulas, stenosis, occlusions, dissections, and tumors). Three experienced and 3 less experienced observers were each shown the acquisitions on a prerelease version of a commercially available double-monitor workstation (XWP, Siemens Healthcare). Acquisitions were presented first as a subtracted image series and then as a single composite color-coded image of the entire acquisition. Observers were then asked a series of questions designed to assess the value of the color-coded images for the following purposes: 1) to enhance their ability to make a diagnosis, 2) to have confidence in their diagnosis, 3) to plan a treatment, and 4) to judge the effect of a treatment. The results were analyzed by using 1-sample Wilcoxon tests. Color-coded images enhanced the ease of evaluating treatment success in >40% of cases (P < .0001). They also had a statistically significant impact on treatment planning, making planning easier in >20% of the cases (P = .0069). In >20% of the examples, color-coding made diagnosis and treatment planning easier for all readers (P < .0001). Color-coding also increased the confidence of diagnosis compared with the use of DSA alone (P = .056). The impact of this was greater for the naïve readers than for the expert readers. At no additional cost in x-ray dose or contrast medium, color-coding of DSA enhanced the conspicuity of findings on DSA images. It was particularly useful in situations in which there was a complex flow pattern and in evaluation of pre- and posttreatment

  5. Automatic extraction of coronary vessels from digital subtraction angiography

    NASA Astrophysics Data System (ADS)

    Tang, Songyuan; Wen, Junhai; Wang, Yongtian; Chen, Yan-wei

    2007-03-01

    In the X-ray coronary digital subtraction angiography, there are serious motion artifacts and noises, and backgrounds such as ribs, spine, cathers and etc, which are tube structures and like vessels. It's difficult to separate vessels from the background automatically if they are close each other. In this paper, an automatic extraction of coronary vessels from X-ray digital subtraction angiography is proposed. We used edge preserving smooth filter to reduce the noises in the images and keep the vessel edge firstly. Then affine and B-spline based FFD nonrigid registration is applied to the images. Compared with the segmentation method, the proposed method can remove background greatly and extract the coronary vessel very well.

  6. Digital subtraction angiography in pediatric cerebrovascular occlusive disease

    SciTech Connect

    Faerber, E.N.; Griska, L.A.B.; Swartz, J.D.; Capitanio, M.A.; Popky, G.L.

    1984-08-01

    While conventional angiography has been used to demonstrate cerebrovascular occlusive disease in the past, digital subtraction angiography (DSA) is capable of showing progressive vascular involvement with ease, simplicity, and extremely low morbidity, making it particularly well suited for children and outpatients either alone or coordinated with computed tomography. The authors discuss the usefulness and advantages of DSA as demonstrated in 7 infants and children with hemiplegia, 4 of whom had sickle-cell disease.

  7. [Clinical value of digital subtraction angiography in cardiology--current status and future prospects].

    PubMed

    Schmiel, F K

    1986-03-01

    Advances in digital technology have made the digital processing of X-ray images possible. The principles of processing, which can be traced back to the early origin of radiology, are characterized by the aims "image enhancement" and "functional imaging". These principles have been routinely applied in digital subtraction angiography (DSA) for visualization of non-moving vessels. DSA is used with caution in cardiology mainly because methodical problems caused by the motion of the background structures. In order to assess the clinical relevance of DSA to cardiology the following questions will be answered: Which structures can be visualized? How large is the error of the parameters determined by DSA? What is the clinical relevance of these parameters? What are the advantages of DSA with regard to the examination procedure? Using DSA the left ventricle can be visualized at rest and during exercise by intravenous injection of contrast medium. The examination procedure can easily be combined with measurements of pulmonary arterial pressure. The errors of left ventricular parameters amount to: ventricular volumes: +/- 12- +/- 18 ml; ejection fraction: +/- 8%; ventricular diameters: +/- 7- +/- 13%; wall volume: +/- 48 ml; wall thickness: +/- 1.6 mm. The image quality of aorto-coronary bypass grafts visualized by intravenously injected contrast medium is sufficient to decide whether the grafts are patent or occluded. The visualization of the proximal segments of coronary arteries by intravenous injection of contrast medium is reported in rare cases.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Quantitative Digital Subtraction Angiography in Pediatric Moyamoya Disease

    PubMed Central

    2015-01-01

    Moyamoya disease is a unique cerebrovascular disorder characterized by idiopathic progressive stenosis at the terminal portion of the internal carotid artery (ICA) and fine vascular network. The aim of this review is to present the clinical application of quantitative digital subtraction angiography (QDSA) in pediatric moyamoya disease. Using conventional angiographic data and postprocessing software, QDSA provides time-contrast intensity curves and then displays the peak time (Tmax) and area under the curve (AUC). These parameters of QDSA can be used as surrogate markers for the hemodynamic evaluation of disease severity and quantification of postoperative neovascularization in moyamoya disease. PMID:26180611

  9. The performance of projective standardization for digital subtraction radiography.

    PubMed

    Mol, André; Dunn, Stanley M

    2003-09-01

    We sought to test the performance and robustness of projective standardization in preserving invariant properties of subtraction images in the presence of irreversible projection errors. Study design Twenty bone chips (1-10 mg each) were placed on dentate dry mandibles. Follow-up images were obtained without the bone chips, and irreversible projection errors of up to 6 degrees were introduced. Digitized image intensities were normalized, and follow-up images were geometrically reconstructed by 2 operators using anatomical and fiduciary landmarks. Subtraction images were analyzed by 3 observers. Regression analysis revealed a linear relationship between radiographic estimates of mineral loss and actual mineral loss (R(2) = 0.99; P <.05). The effect of projection error was not significant (general linear model [GLM]: P >.05). There was no difference between the radiographic estimates from images standardized with anatomical landmarks and those standardized with fiduciary landmarks (Wilcoxon signed rank test: P >.05). Operator variability was low for image analysis alone (R(2) = 0.99; P <.05), as well as for the entire procedure (R(2) = 0.98; P <.05). The predicted detection limit was smaller than 1 mg. Subtraction images registered by projective standardization yield estimates of osseous change that are invariant to irreversible projection errors of up to 6 degrees. Within these limits, operator precision is high and anatomical landmarks can be used to establish correspondence.

  10. Using a digital signal processor as a data stream controller for digital subtraction angiography

    SciTech Connect

    Meng, J.D.; Katz, J.E.

    1991-10-01

    High speed, flexibility, and good arithmetic abilities make digital signal processors (DSP) a good choice as input/output controllers for real time applications. The DSP can be made to pre-process data in real time to reduce data volume, to open early windows on what is being acquired and to implement local servo loops. We present an example of a DSP as an input/output controller for a digital subtraction angiographic imaging system. The DSP pre-processes the raw data, reducing data volume by a factor of two, and is potentially capable of producing real-time subtracted images for immediate display.

  11. Motion compensation in digital subtraction angiography using graphics hardware.

    PubMed

    Deuerling-Zheng, Yu; Lell, Michael; Galant, Adam; Hornegger, Joachim

    2006-07-01

    An inherent disadvantage of digital subtraction angiography (DSA) is its sensitivity to patient motion which causes artifacts in the subtraction images. These artifacts could often reduce the diagnostic value of this technique. Automated, fast and accurate motion compensation is therefore required. To cope with this requirement, we first examine a method explicitly designed to detect local motions in DSA. Then, we implement a motion compensation algorithm by means of block matching on modern graphics hardware. Both methods search for maximal local similarity by evaluating a histogram-based measure. In this context, we are the first who have mapped an optimizing search strategy on graphics hardware while paralleling block matching. Moreover, we provide an innovative method for creating histograms on graphics hardware with vertex texturing and frame buffer blending. It turns out that both methods can effectively correct the artifacts in most case, as the hardware implementation of block matching performs much faster: the displacements of two 1024 x 1024 images can be calculated at 3 frames/s with integer precision or 2 frames/s with sub-pixel precision. Preliminary clinical evaluation indicates that the computation with integer precision could already be sufficient.

  12. Multinuclide digital subtraction imaging in symptomatic prostnetic joints

    SciTech Connect

    Chafetz, N.; Hattner, R.S.; Ruarke, W.C.; Helms, C.A.; Genant, H.K.; Murray, W.R.

    1985-06-01

    One hundred eleven patients with symptomatic prosthetic joints (86 hips, 23 knees, and two shoulders) were evaluated for prosthetic loosening and infection by combined technetium-99m-MDP/gallium-67 digital subtraction imaging. Clinical correlation was based on the assessment of loosening and bacterial cultures obtained at the time of surgery in 54 patients, joint aspiration cultures obtained in 37 patients, and long-term clinical follow-up for greater than 1.5 years in an additional 15 patients. Results revealed an 80-90% predictive value of a positive test for loosening, and a 95% predictive value of a negative test for infection. However, because of the low sensitivities and specificities observed, this approach to the evaluation of symptomatic prosthetic joints does not seem cost effective.

  13. The Principle of Digital Subtraction Angiography and Radiological Protection

    PubMed Central

    Okamoto, K.; Ito, J.; Sakai, K.; Yoshimura, S.

    2000-01-01

    Summary Recent improvements in x-ray technology have greatly contributed to the advancement of diagnostic imaging. Fluoroscopically guided neurointerventional procedures with digital subtraction angiography (DSΛ) are being performed with increasing frequency as the treatment of choice for a variety of neurovascular diseases. Radiation-induced skin injuries can occur after extended fluoroscopic exposure times, and the injuries have recently been reported. In this article, measured radiation doses at the surface of Rando Phantom with Skin Dose Monitor, and estimated and measured entrance skin doses in patients underwent neurointerventional procedures are reported as well as means of reducing radiation doses absorbed by patients and personnel to avoid occurrence of radiation-induced injuries. PMID:20667218

  14. Digital subtraction angiography for preoperative evaluation of extremity tumors

    SciTech Connect

    Paushter, D.M.; Borkowski, G.R.; Buonocore, E.; Belhobek, G.H.; Marks, K.E.

    1983-07-01

    A retrospective study was undertaken to evaluate the role of digital subtraction angiography (DSA) in the surgical planning of musculoskeletal neoplasms. Thirteen patients with primary bone and soft-tissue tumors were examined by CT and DSA. Three patients also had conventional angiography. DSA yielded surgically useful information in 10 patients, comparable to that expected from conventional angiography. DSA was most helpful in demonstrating the presence or absence of major vessel involvement by tumor when this could not be ascertained definitely on CT. Demonstration of mass extent by CT was accurate in 11 patients. Results of this study suggest that the combination of CT and DSA is useful in the preoperative evaluation of selected extremity tumors and should diminish the need for conventional angiography.

  15. How Do Manipulatives Help Students Communicate Their Understanding of Double-Digit Subtraction?

    ERIC Educational Resources Information Center

    Abi-Hanna, Rabab

    2016-01-01

    Multi-digit subtraction is difficult for students to learn. The purpose of this study is to explore how second-grade students communicate their understanding of double-digit subtraction through the use of manipulatives/tools. This qualitative study reports on six case studies of second-grade students where clinical interviews were the main source…

  16. How Do Manipulatives Help Students Communicate Their Understanding of Double-Digit Subtraction?

    ERIC Educational Resources Information Center

    Abi-Hanna, Rabab

    2016-01-01

    Multi-digit subtraction is difficult for students to learn. The purpose of this study is to explore how second-grade students communicate their understanding of double-digit subtraction through the use of manipulatives/tools. This qualitative study reports on six case studies of second-grade students where clinical interviews were the main source…

  17. Efficiency and Flexibility of Indirect Addition in the Domain of Multi-Digit Subtraction

    ERIC Educational Resources Information Center

    Torbeyns, Joke; Ghesquiere, Pol; Verschaffel, Lieven

    2009-01-01

    This article discusses the characteristics of the indirect addition strategy (IA) in the domain of multi-digit subtraction. In two studies, adults' use of IA on three-digit subtractions with a small, medium, or large difference between the integers was analysed using the choice/no-choice method. Results from both studies indicate that adults…

  18. Parametric Imaging Of Digital Subtraction Angiography Studies For Renal Transplant Evaluation

    NASA Astrophysics Data System (ADS)

    Gallagher, Joe H.; Meaney, Thomas F.; Flechner, Stuart M.; Novick, Andrew C.; Buonocore, Edward

    1981-11-01

    A noninvasive method for diagnosing acute tubular necrosis and rejection would be an important tool for the management of renal transplant patients. From a sequence of digital subtraction angiographic images acquired after an intravenous injection of radiographic contrast material, the parametric images of the maximum contrast, the time when the maximum contrast is reached, and two times the time at which one half of the maximum contrast is reached are computed. The parametric images of the time when the maximum is reached clearly distinguish normal from abnormal renal function. However, it is the parametric image of two times the time when one half of the maximum is reached which provides some assistance in differentiating acute tubular necrosis from rejection.

  19. Image noise reduction algorithm for digital subtraction angiography: clinical results.

    PubMed

    Söderman, Michael; Holmin, Staffan; Andersson, Tommy; Palmgren, Charlotta; Babic, Draženko; Hoornaert, Bart

    2013-11-01

    To test the hypothesis that an image noise reduction algorithm designed for digital subtraction angiography (DSA) in interventional neuroradiology enables a reduction in the patient entrance dose by a factor of 4 while maintaining image quality. This clinical prospective study was approved by the local ethics committee, and all 20 adult patients provided informed consent. DSA was performed with the default reference DSA program, a quarter-dose DSA program with modified acquisition parameters (to reduce patient radiation dose exposure), and a real-time noise-reduction algorithm. Two consecutive biplane DSA data sets were acquired in each patient. The dose-area product (DAP) was calculated for each image and compared. A randomized, blinded, offline reading study was conducted to show noninferiority of the quarter-dose image sets. Overall, 40 samples per treatment group were necessary to acquire 80% power, which was calculated by using a one-sided α level of 2.5%. The mean DAP with the quarter-dose program was 25.3% ± 0.8 of that with the reference program. The median overall image quality scores with the reference program were 9, 13, and 12 for readers 1, 2, and 3, respectively. These scores increased slightly to 12, 15, and 12, respectively, with the quarter-dose program imaging chain. In DSA, a change in technique factors combined with a real-time noise-reduction algorithm will reduce the patient entrance dose by 75%, without a loss of image quality. RSNA, 2013

  20. Accurate geometric calibration in stepping-table digital subtraction angiography.

    PubMed

    Schmidt, M A; Nayak, S L; Belli, A-M; Britten, A J

    2007-10-01

    Accurate measurements of vessel dimensions are desirable in many clinical applications. This work uses the known relative motion between X-ray source and the patient in stepping-table digital subtraction angiography (DSA) to provide an accurate geometric calibration for quantitative measurements. The method results in a calibration factor that converts the size of the object measured in pixels on the image to its size in millimetres. The main sources of error relate to: (i) the assessment of relative displacement of a structure in a series of images; (ii) patient motion throughout data acquisition; and (iii) image distortion. Error was evaluated both with a test object consisting of a large grid of ball bearings (2x2 cm spaced) and, in vivo, in five renal DSA examinations performed with identical catheters of known diameter. The calibration factor was calculated with 0.1% accuracy for the test object and at least 2% accuracy in vivo, even with breath holding and pulsatile motion. This demonstrates that the calculation of the calibration factor can be very accurate, and that the method we propose is capable of the submillimetre accuracy required for clinical studies if used in conjunction with an accurate measurement of the vessel size in pixels. In conclusion, accurate geometric measurements can be performed in stepping-table DSA, without the need for external reference objects.

  1. Intraoperative spinal digital subtraction angiography: technique and results.

    PubMed

    Benes, Ludwig; Wakat, Jörg-Peter; Sure, Ulrich; Bien, Siegfried; Bertalanffy, Helmut

    2003-03-01

    To evaluate technical and methodological aspects of intraoperative spinal digital subtraction angiography (ISDSA) in our clinical practice and to assess its practicability, safety, and accuracy for the surgical treatment of spinal vascular malformations. Between August 1997 and February 2002, a total of 30 patients were treated either surgically (n = 18) or endovascularly (n = 12) for spinal vascular lesions at our institution. The clinical records of five patients who underwent ISDSA were analyzed retrospectively. The thoracic segment was involved in three patients and the medullary cone in two. ISDSA could be performed in four cases. In one patient, the segmental artery could not be probed sufficiently while the patient was prone. No complications occurred from the application of ISDSA. The method was beneficial for the neurosurgeon in all but one patient because the vascular anatomy of the malformation was shown with respect to the surgical approach, including the nidus, and immediate resection control could be performed before wound closure. The duration of the procedure was prolonged by 45 minutes on average. ISDSA is safe and effective, especially in surgery for complex vascular and recurrent malformations. Benefits to the patient outweigh the additional expense and prolongation of the surgical procedure.

  2. Mental Computation or Standard Algorithm? Children's Strategy Choices on Multi-Digit Subtractions

    ERIC Educational Resources Information Center

    Torbeyns, Joke; Verschaffel, Lieven

    2016-01-01

    This study analyzed children's use of mental computation strategies and the standard algorithm on multi-digit subtractions. Fifty-eight Flemish 4th graders of varying mathematical achievement level were individually offered subtractions that either stimulated the use of mental computation strategies or the standard algorithm in one choice and two…

  3. Mental Computation or Standard Algorithm? Children's Strategy Choices on Multi-Digit Subtractions

    ERIC Educational Resources Information Center

    Torbeyns, Joke; Verschaffel, Lieven

    2016-01-01

    This study analyzed children's use of mental computation strategies and the standard algorithm on multi-digit subtractions. Fifty-eight Flemish 4th graders of varying mathematical achievement level were individually offered subtractions that either stimulated the use of mental computation strategies or the standard algorithm in one choice and two…

  4. Interobserver Agreement on Arteriovenous Malformation Diffuseness Using Digital Subtraction Angiography.

    PubMed

    Braileanu, Maria; Yang, Wuyang; Caplan, Justin M; Lin, Li-Mei; Radvany, Martin G; Tamargo, Rafael J; Huang, Judy

    2016-11-01

    Arteriovenous malformation (AVM) diffuseness has been shown to be prognostic of treatment outcomes. We assessed interobserver agreement of AVM diffuseness among physicians of different specialty and training backgrounds using digital subtraction angiography (DSA). All research protocols were approved by the institutional review board for this retrospective chart review. In a single-blinded setting, 2 attending neurosurgeons, 1 attending interventional neuroradiologist, and 1 senior neurosurgical resident rated 80 DSA views of 36 AVMs as either compact or diffuse. Individual interobserver agreement and subgroup agreement were analyzed using κ agreement and intraclass correlation coefficient. Disagreement regarding AVM diffuseness occurred in 43.8% of all DSA views (n = 80). Interobserver κ agreement on AVM diffuseness using DSA views among 4 physicians ranged from fair (κ = 0.40 [95% confidence interval (CI) = 0.22-0.58]) to substantial (κ = 0.65 [95% CI = 0.48-0.81]), whereas total intraclass correlation coefficient was 0.81 (95% CI = 0.73-0.87). For the 36 AVMs, κ agreement ranged from fair (κ = 0.36 [95% CI = 0.13-0.60]) to moderate (κ = 0.57 [95% CI = 0.35-0.79]), whereas intraclass correlation coefficient among all 4 physicians was 0.68 (95% CI = 0.47-0.82). Moderate agreement on AVM diffuseness (n = 80) was found between attending and resident assessments (κ = 0.57 [95% CI = 0.39-0.75]) and between neurosurgeon and interventional neuroradiologist assessments (κ = 0.55 [95% CI = 0.37-0.73]). Agreement of individual physicians on AVM diffuseness varies from fair to substantial. Objective and three-dimensional measures of AVM diffuseness should be developed for consistent clinical application. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Personal computer equipment for dental digital subtraction radiography vs. industrial computer equipment and conventional radiography.

    PubMed

    Möystad, A; Svanaes, D B; Larheim, T A

    1992-04-01

    A "low-cost" personal computer (PC) system used to digitize dental radiographs was tested by assessing the accuracy of its subtraction images versus those of "high-cost" industrial equipment and conventional radiography. Subtraction images were made of artificial lesions in human femur bone and subsequently evaluated by students and teachers. The observations were analyzed in terms of true positive and false positive reports. "Low-cost" and "high-cost" subtraction images revealed only small differences in diagnostic accuracy. Compared to conventional radiography, the diagnostic accuracy of the subtraction images with the "low-cost" PC system was significantly higher for all observers. The interexaminer variance was similar for the subtraction and the conventional images for both students and teachers, except for a significantly reduced interexaminer variance for the teachers concerning the true positive reports with the "low-cost" PC subtraction technique.

  6. Evaluation of simulated external root resorptions with digital radiography and digital subtraction radiography.

    PubMed

    Ono, Evelise; Medici Filho, Edmundo; Faig Leite, Horacio; Tanaka, Jefferson Luis Oshiro; De Moraes, Mari Eli Leonelli; De Melo Castilho, Julio Cezar

    2011-03-01

    Root resorption can cause damage in orthodontic patients. Digital subtraction radiography (DSR) is a useful resource for the detection of mineral losses. The purpose of this study was to compare the efficacy of digital radiography (DR) and DSR in detecting simulated external root resorption. Examiner agreement between the 2 techniques was also evaluated. Root resorptions of various sizes were simulated on the apical and lingual aspects of 49 teeth from 9 dry human mandibles. The teeth were radiographed in standardized conditions. The radiographs were registered with Regeemy Image Registration and Mosaicking (version 0.2.43-RCB, DPI-INPE, São José dos Campos, São Paulo, Brazil) and subtracted with Image Tool (University of Texas Health Science Center at San Antonio). The subtracted images and the digital radiographs were evaluated by 3 oral radiologists. No statistically significant differences were found for the methods in the detection of apical root resorptions, independently from lesion size, and of lingual resorptions of 1.2 mm or greater. DSR was significantly better than DR for detection of lingual resorptions up to 1 mm. Resorptions less than 0.5 mm were not precisely detected by either method. DSR provided better intraexaminer and interexaminer agreement than did DR. Both methods are precise for detection of apical root resorptions as small as 0.5 mm and lingual resorptions of 1 mm or more. However, DSR frequently performed better than did DR. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  7. Temporal Subtraction of Digital Breast Tomosynthesis Images for Improved Mass Detection

    DTIC Science & Technology

    2007-10-01

    Tomosynthesis Images for Improved Mass Detection PRINCIPAL INVESTIGATOR: Christina M. Li...DATES COVERED 15 Sep 2006 – 14 Sep 2007 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Temporal Subtraction of Digital Breast Tomosynthesis Images for...13. SUPPLEMENTARY NOTES 14. ABSTRACT Digital breast tomosynthesis (DBT) strives to overcome the obstacles presented in conventional 2D

  8. [Development of a digital chest phantom for studies on energy subtraction techniques].

    PubMed

    Hayashi, Norio; Taniguchi, Anna; Noto, Kimiya; Shimosegawa, Masayuki; Ogura, Toshihiro; Doi, Kunio

    2014-03-01

    Digital chest phantoms continue to play a significant role in optimizing imaging parameters for chest X-ray examinations. The purpose of this study was to develop a digital chest phantom for studies on energy subtraction techniques under ideal conditions without image noise. Computed tomography (CT) images from the LIDC (Lung Image Database Consortium) were employed to develop a digital chest phantom. The method consisted of the following four steps: 1) segmentation of the lung and bone regions on CT images; 2) creation of simulated nodules; 3) transformation to attenuation coefficient maps from the segmented images; and 4) projection from attenuation coefficient maps. To evaluate the usefulness of digital chest phantoms, we determined the contrast of the simulated nodules in projection images of the digital chest phantom using high and low X-ray energies, soft tissue images obtained by energy subtraction, and "gold standard" images of the soft tissues. Using our method, the lung and bone regions were segmented on the original CT images. The contrast of simulated nodules in soft tissue images obtained by energy subtraction closely matched that obtained using the gold standard images. We thus conclude that it is possible to carry out simulation studies based on energy subtraction techniques using the created digital chest phantoms. Our method is potentially useful for performing simulation studies for optimizing the imaging parameters in chest X-ray examinations.

  9. Digital subtraction cisternography: a new approach to fistula localisation in cerebrospinal fluid rhinorrhoea.

    PubMed Central

    Byrne, J V; Ingram, C E; MacVicar, D; Sullivan, F M; Uttley, D

    1990-01-01

    Positive contrast cisternography with digital subtraction of fluoroscopy images before computed tomography (CT) was employed in the investigation of eight patients with cerebrospinal fluid (CSF) rhinorrhoea. Fistulae were visualised by preliminary digital subtraction cisternography (DSC) in six patients and in five patients the sites of leakage were confirmed at surgery. Fluoroscopy facilitated interpretation of CT in all the positive studies and in two patients provided information which could not be deduced from CT cisternography (CTC) alone. The combined technique is recommended for the investigation of patients with recurrent and post operative CSF rhinorrhoea and when CTC alone fails to identify the site of leakage. Images PMID:2292701

  10. [The improved design of table operating box of digital subtraction angiography device].

    PubMed

    Qi, Xianying; Zhang, Minghai; Han, Fengtan; Tang, Feng; He, Lemin

    2009-12-01

    In this paper are analyzed the disadvantages of CGO-3000 digital subtraction angiography table Operating Box. The authors put forward a communication control scheme between single-chip microcomputer(SCM) and programmable logic controller(PLC). The details of hardware and software of communication are given.

  11. Digital Subtraction Cystography for Detection of Communicating Holes of Spinal Extradural Arachnoid Cysts.

    PubMed

    Gu, Kyowon; Kwon, Jong Won; Kim, Eun-Sang

    2016-01-01

    The purpose of this study was to demonstrate the usefulness of digital subtraction cystography to identify communicating holes between a spinal extradural arachnoid cyst (SEAC) and the subarachnoid space prior to cyst removal and hole closure. Six patients with SEAC were enrolled in this retrospective study. Digital subtraction cystography and subsequent CT myelography were performed for every patient. The presence and location of the communicating holes on cystography were documented. We evaluated the MRI characteristics of the cysts, including location, size, and associated spinal cord compression; furthermore, we reviewed cystographic images, CT myelograms, procedural reports, and medical records for analysis. If surgery was performed after cystography, intraoperative findings were compared with preoperative cystography. The location of the communicating hole between the arachnoid cyst and the subarachnoid space was identified by digital subtraction cystography in all cases (n = 6). Surgical resection of SEAC was performed in 4 patients, and intraoperative location of the communicating hole exactly corresponded to the preoperative identification. Fluoroscopic-guided cystography for SEAC accurately demonstrates the presence and location of dural defects. Preoperative digital subtraction cystography is useful for detection of a communicating hole between a cyst and the subarachnoid space.

  12. Digital Subtraction of Magnetic Resonance Images Improves Detection and Characterization of Pancreatic Neuroendocrine Neoplasms.

    PubMed

    De Robertis, Riccardo; Tinazzi Martini, Paolo; Cingarlini, Sara; Ortolani, Silvia; Butturini, Giovanni; Regi, Paolo; Landoni, Luca; Tortora, Giampaolo; Pederzoli, Paolo; D'Onofrio, Mirko

    The aim of this study was to evaluate the usefulness of digital image subtraction of contrast-enhanced magnetic resonance (MR) images for detection and characterization of pancreatic neuroendocrine neoplasms (PanNENs). Magnetic resonance examinations of 50 histologically verified PanNENs were retrospectively evaluated by 2 radiologists; 50 ductal adenocarcinomas were included as a control group. Late arterial phase images and correspondent subtracted images were analyzed. Tumor detectability on a subjective 3-point scale and contrast-to-noise ratios were compared across sequences using paired Student t tests. Tumor signal intensity was compared between sequences using χ or Fisher exact tests. Subjective conspicuity and contrast-to-noise ratios of PanNENs were significantly higher on subtracted images compared with correspondent late arterial phase images (P < 0.001 and P = 0.002). The rate of clearly hyperenhancing PanNENs was higher on subtracted images compared with arterial phase images (76% vs 36%). Digital image subtraction improves tumor conspicuity and allows better characterization of PanNENs compared with late arterial phase images.

  13. Digital subtraction peripheral angiography using image stacking: initial clinical results.

    PubMed

    Kump, K S; Sachs, P B; Wilson, D L

    2001-07-01

    Using clinically acquired x-ray angiography image sequences, we compared three algorithms for creating a single diagnostic quality image that combined input images containing flowing contrast agent. These image-stacking algorithms were: maximum opacity with the minimum gray-scale value across time recorded at each spatial location, (REC) recursive temporal filtering followed by a maximum opacity operation, and (AMF) an approximate matched filter consisting of a convolution with a kernel approximating the matched filter followed by a maximum opacity operation. Eighteen clinical exams of the peripheral arteries of the legs were evaluated. AMF gave 2.7 times greater contrast to noise ratio than the single best subtraction image and 1.3 times improvement over REC, the second best stacking algorithm. This is consistent with previous simulations showing that AMF performs nearly equal to the optimal result from matched filtering without the well-known limitations. For example, unlike matched filtering, AMF filter coefficients were obtained automatically using an image-processing algorithm. AMF effectively brought out small collateral arteries, otherwise difficult to see, without degrading artery sharpness or stenosis grading. Comparing results using reduced and full contrast agent volumes demonstrated that contrast agent load could be reduced to one-third of the conventional amount with AMF processing. By simulating reduced x-ray exposures on clinical exams, we determined that x-ray exposure could be reduced by 80% with AMF processing. We conclude that AMF is a promising, potential technique for reducing contrast agent load and for improving vessel visibility, both very important characteristics for vascular imaging.

  14. Accuracy of Digital Subtraction Radiography in the Detection of Vertical Root Fractures.

    PubMed

    Queiroz, Polyane Mazucatto; Nascimento, Helena Aguiar Ribeiro; da Paz, Thais Diniz Jacome; Anacleto, Felipe Nogueira; Freitas, Deborah Queiroz

    2016-06-01

    The objective of this study was to evaluate the accuracy of digital subtraction radiography in the diagnosis of vertical root fractures (VRFs). Twenty decoronated uniradicular human teeth were placed in the alveoli of a dry mandible and radiographed twice, first without (unfilled roots) and then with (filled roots) a gutta-percha cone placed into the root canal. Roots were then removed from the dry mandible, and vertical fractures were created with the aid of a universal testing machine. The fractured roots were repositioned in the mandibular alveoli and again radiographed twice. Radiographic images were subtracted by using the Regeemy software in 3 test situations: group 1, initial radiographic images of unfilled roots and images of fractured or non-fractured unfilled roots; group 2, initial radiographic images of unfilled roots and images of fractured or non-fractured filled roots; and group 3, initial radiographic images of filled roots and images of fractured or non-fractured filled roots. Three examiners evaluated all the original digital radiographs, as well as the subtracted images, for the presence or absence of VRFs. Numerical data were subject to statistical analysis with the use of receiver operator characteristic (ROC) curves. The areas under the ROC curve for groups 1, 2, and 3 were 0.86, 0.73, and 0.66, respectively. For the original digital radiographs, areas under the ROC curve were 0.80 (without gutta-percha) and 0.73 (with gutta-percha). No statistically significant differences were found between subtracted and original images. Digital subtraction radiography could be considered as an alternative tool for the investigation of VRFs because of its comparable diagnostic accuracy to existing methods. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  15. Digital image comparison by subtracting contextual transformations—percentile rank order differentiation

    USGS Publications Warehouse

    Wehde, M. E.

    1995-01-01

    The common method of digital image comparison by subtraction imposes various constraints on the image contents. Precise registration of images is required to assure proper evaluation of surface locations. The attribute being measured and the calibration and scaling of the sensor are also important to the validity and interpretability of the subtraction result. Influences of sensor gains and offsets complicate the subtraction process. The presence of any uniform systematic transformation component in one of two images to be compared distorts the subtraction results and requires analyst intervention to interpret or remove it. A new technique has been developed to overcome these constraints. Images to be compared are first transformed using the cumulative relative frequency as a transfer function. The transformed images represent the contextual relationship of each surface location with respect to all others within the image. The process of differentiating between the transformed images results in a percentile rank ordered difference. This process produces consistent terrain-change information even when the above requirements necessary for subtraction are relaxed. This technique may be valuable to an appropriately designed hierarchical terrain-monitoring methodology because it does not require human participation in the process.

  16. Impact of JPEG lossy image compression on quantitative digital subtraction radiography.

    PubMed

    Fidler, A; Likar, B; Pernus, F; Skaleric, U

    2002-03-01

    The aim of the study was to evaluate the impact of JPEG lossy image compression on the estimation of alveolar bone gain by quantitative digital subtraction radiography (DSR). Nine dry domestic pig mandible posterior segments were radiographed three times ('Baseline', 'No change', and 'Gain') with standardized projection geometry. Bone gain was simulated by adding artificial bone chips (1, 4, and 15 mg). Images were either compressed before or after registration. No change areas in compressed and subtracted 'No change-Baseline' images and bone gain volumes in compressed and subtracted 'Gain-Baseline' images were calculated and compared to the corresponding measurements performed on original subtracted images. Measurements of no change areas ('No change-Baseline') were only slightly affected by compressions down to JPEG 50 (J50) applied either before or after registration. Simulated gain of alveolar bone ('Gain-Baseline') was underestimated when compression before registration was performed. The underestimation was bigger when small bone chips of 1 mg were measured and when higher compression rates were used. Bone chips of 4 and 15 mg were only slightly underestimated when using J90, J70, and J50 compressions before registration. Lossy JPEG compression does not affect the measurements of no change areas by DSR. Images undergoing subtraction should be registered before compression and if so, J90 compression with a compression ratio of 1:7 can be used to detect and measure 4 mg and larger bone gain.

  17. The association between children's numerical magnitude processing and mental multi-digit subtraction.

    PubMed

    Linsen, Sarah; Verschaffel, Lieven; Reynvoet, Bert; De Smedt, Bert

    2014-01-01

    Children apply various strategies to mentally solve multi-digit subtraction problems and the efficient use of some of them may depend more or less on numerical magnitude processing. For example, the indirect addition strategy (solving 72-67 as "how much do I have to add up to 67 to get 72?"), which is particularly efficient when the two given numbers are close to each other, requires to determine the proximity of these two numbers, a process that may depend on numerical magnitude processing. In the present study, children completed a numerical magnitude comparison task and a number line estimation task, both in a symbolic and nonsymbolic format, to measure their numerical magnitude processing. We administered a multi-digit subtraction task, in which half of the items were specifically designed to elicit indirect addition. Partial correlational analyses, controlling for intellectual ability and motor speed, revealed significant associations between numerical magnitude processing and mental multi-digit subtraction. Additional analyses indicated that numerical magnitude processing was particularly important for those items for which the use of indirect addition is expected to be most efficient. Although this association was observed for both symbolic and nonsymbolic tasks, the strongest associations were found for the symbolic format, and they seemed to be more prominent on numerical magnitude comparison than on number line estimation.

  18. Information synthesis (complex amplitude addition and subtraction) and encryption with digital holography and virtual optics.

    PubMed

    Wang, Xiaogang; Zhao, Daomu; Jing, Feng; Wei, Xiaofeng

    2006-02-20

    A new method is proposed in this paper for the synthesis and encryption of information with digital holography technique and virtual optics. By using a three-step phase-shifting interferometry, the fused or subtracted digital hologram can be calculated from different interference patterns. To protect the digital data that can be transmitted through communication channel, an encryption approach based on virtual optics is also proposed. The encryption method proposed is based on extended fractional Fourier transforms. Both the encryption and decryption processes are performed in all-digital manner. The encrypted data and the synthesized data reconstructed numerically also can be stored and transmitted in the conventional communication channel. Numerical simulation results are given to verify the proposed idea.

  19. Comparative evaluation of JPEG and JPEG2000 compression in quantitative digital subtraction radiography.

    PubMed

    Fidler, A; Likar, B; Pernus, F; Skaleric, U

    2002-11-01

    The aim of this in vitro study was to compare the impact of JPEG and the novel JPEG2000 compression standard on quantitative digital subtraction radiography (DSR) and to determine the acceptable JPEG2000 compression ratios for DSR. Nine dry pig mandible sections were radiographed three times ('Baseline', 'No change', and 'Gain') with standardized projection geometry. Bone gain was simulated by adding artificial bone chips (1, 4 and 15 mg). Images were registered, compressed by JPEG and JPEG2000 using compression ratios (CR) of 1 : 7, 1 : 16, 1 : 22, and 1 : 31, and then subtracted. Image distortion was assessed objectively by calculating average pixel error and peak signal to noise ratio. No change areas in compressed and subtracted 'No change-Baseline' images and bone gain volumes in compressed and subtracted 'Gain-Baseline' images were calculated for both compression standards and compared. JPEG introduced less distortion at low CRs, while JPEG2000 was superior at higher CRs. At CR of 1 : 7, no significant difference between JPEG and JPEG2000 was found. JPEG2000 yielded better results for no change measurements at higher CRs. Volumes of simulated bone gain were overestimated when JPEG and underestimated when JPEG2000 compression was used. At CR of 1 : 7 JPEG and JPEG2000 performed similarly, which indicates that CR of 1:7 in JPEG2000 can be used for DSR if images are registered before compression. At higher CRs, JPEG2000 is superior to JPEG but image distortions are too high for reliable quantitative DSR.

  20. Strategies for Human Tumor Virus Discoveries: From Microscopic Observation to Digital Transcriptome Subtraction

    PubMed Central

    Mirvish, Ezra D.; Shuda, Masahiro

    2016-01-01

    Over 20% of human cancers worldwide are associated with infectious agents, including viruses, bacteria, and parasites. Various methods have been used to identify human tumor viruses, including electron microscopic observations of viral particles, immunologic screening, cDNA library screening, nucleic acid hybridization, consensus PCR, viral DNA array chip, and representational difference analysis. With the Human Genome Project, a large amount of genetic information from humans and other organisms has accumulated over the last decade. Utilizing the available genetic databases, Feng et al. (2007) developed digital transcriptome subtraction (DTS), an in silico method to sequentially subtract human sequences from tissue or cellular transcriptome, and discovered Merkel cell polyomavirus (MCV) from Merkel cell carcinoma. Here, we review the background and methods underlying the human tumor virus discoveries and explain how DTS was developed and used for the discovery of MCV. PMID:27242703

  1. Bone marrow edema pattern identification in patients with lytic bone lesions using digital subtraction angiography-like bone subtraction on large-area detector computed tomography.

    PubMed

    Gondim Teixeira, Pedro Augusto; Hossu, Gabriela; Lecocq, Sophie; Razeto, Marco; Louis, Matthias; Blum, Alain

    2014-03-01

    The objective of this study was to evaluate the performance of digital subtraction angiography (DSA)-like bone subtraction with 2 different registration methods for the identification of bone marrow edema pattern (BMEP) in patients with lytic bone lesions, using magnetic resonance imaging as the criterion standard. Fifty-five patients with a lytic bone lesion were included in this prospective study with approval from the ethics committee. All patients underwent magnetic resonance imaging and low-dose computed tomographic (CT) perfusion after signing an informed consent. Two CT volumes were used for bone subtraction, which was performed with 2 different algorithms (rigid and nonrigid). Enhancement at the nonlytic bone marrow was considered as a sign of BMEP. Two readers evaluated the images blindly. The presence of BMEP on bone-subtracted CT images was evaluated subjectively and quantitatively. Image quality was assessed. Magnetic resonance imaging was used as the criterion standard. Using a rigid registration method, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CT with DSA-like bone subtraction BMEP was 77%, 100%, 100%, 68%, and 85%, respectively. The interobserver agreement was good (κ, 0.782). Image quality was better using a nonrigid registration. With this algorithm, artifacts interfered with image interpretation in only 5% of cases. However, there was a noticeable drop in sensitivity and negative predictive value when a nonrigid algorithm was used: 56% and 52%, respectively. The interobserver agreement was average with a nonrigid subtraction algorithm. Computed tomography with DSA-like bone subtraction is sensitive and highly specific for the identification of BMEP associated with lytic bone lesions. Rigid registering should be preferred, but nonrigid algorithms can be used as a second option when artifacts interfere with image interpretation.

  2. Accuracy of digital subtraction radiography in combination with a contrast media in assessment of proximal caries depth.

    PubMed

    Valizadeh, Solmaz; Ehsani, Sara; Esmaeili, Farzad; Tavakoli, Mohammad Amin

    2008-01-01

    Radiography is used to diagnose the demineralization process and carious lesions; however, conventional radiography and direct digital images do not show these lesions when the amount of demineralization is less than 40%. Digital subtraction radiography has recently been used to improve the diagnostic quality of these le-sions. The purpose of this study was to compare the caries depth estimated by digital subtraction radiog-raphy in combination with barium sulfate in diag-nosing proximal dental caries with histopathologic evaluation. In this study 30 molars and premolars (24 demineralized lesions with cavity, 8 without cavity) were studied. Direct digital images were taken (kVp: 68, mA: 8; t: 0.12 for premolars and t: 0.16 for molars) whereas the position of X-ray tube and CCD receptor and teeth was fixed. To prepare the second images 135 gr/L barium sulfate was used. The images obtained with the same exposure and geometry and then subtracted. The depth of the lesions in direct digital and subtracted images were assessed and compared with the depth measured in histopathologic assessments. The mean depths (± SD) of the lesions were 1.80 ± 0.77 mm in direct digital radiography, 2.32 ± 0.76 mm in subtracted images after barium sulfate treatment, and 2.51 ± 0.43 mm in histopathologic sections. The statistical difference between direct digital radiography and the other methods was significant (P < 0.05). However, the differences were not statistically significant between subtracted images and histopathologic sections. The average intra-class correlation coefficient was 0.7241 (CI: 95%). The present study has demonstrated that digital subtraction radiography images have the potential to measure the depth of proximal caries with no significant difference with histopathologic evaluation.

  3. Digital Subtraction Phonocardiography (DSP) applied to the detection and characterization of heart murmurs

    PubMed Central

    2011-01-01

    Background During the cardiac cycle, the heart normally produces repeatable physiological sounds. However, under pathologic conditions, such as with heart valve stenosis or a ventricular septal defect, blood flow turbulence leads to the production of additional sounds, called murmurs. Murmurs are random in nature, while the underlying heart sounds are not (being deterministic). Innovation We show that a new analytical technique, which we call Digital Subtraction Phonocardiography (DSP), can be used to separate the random murmur component of the phonocardiogram from the underlying deterministic heart sounds. Methods We digitally recorded the phonocardiogram from the anterior chest wall in 60 infants and adults using a high-speed USB interface and the program Gold Wave http://www.goldwave.com. The recordings included individuals with cardiac structural disease as well as recordings from normal individuals and from individuals with innocent heart murmurs. Digital Subtraction Analysis of the signal was performed using a custom computer program called Murmurgram. In essence, this program subtracts the recorded sound from two adjacent cardiac cycles to produce a difference signal, herein called a "murmurgram". Other software used included Spectrogram (Version 16), GoldWave (Version 5.55) as well as custom MATLAB code. Results Our preliminary data is presented as a series of eight cases. These cases show how advanced signal processing techniques can be used to separate heart sounds from murmurs. Note that these results are preliminary in that normal ranges for obtained test results have not yet been established. Conclusions Cardiac murmurs can be separated from underlying deterministic heart sounds using DSP. DSP has the potential to become a reliable and economical new diagnostic approach to screening for structural heart disease. However, DSP must be further evaluated in a large series of patients with well-characterized pathology to determine its clinical potential

  4. Digital Subtraction Phonocardiography (DSP) applied to the detection and characterization of heart murmurs.

    PubMed

    Akbari, Mohammad Ali; Hassani, Kamran; Doyle, John D; Navidbakhsh, Mahdi; Sangargir, Maryam; Bajelani, Kourosh; Ahmadi, Zahra Sadat

    2011-12-20

    During the cardiac cycle, the heart normally produces repeatable physiological sounds. However, under pathologic conditions, such as with heart valve stenosis or a ventricular septal defect, blood flow turbulence leads to the production of additional sounds, called murmurs. Murmurs are random in nature, while the underlying heart sounds are not (being deterministic). We show that a new analytical technique, which we call Digital Subtraction Phonocardiography (DSP), can be used to separate the random murmur component of the phonocardiogram from the underlying deterministic heart sounds. We digitally recorded the phonocardiogram from the anterior chest wall in 60 infants and adults using a high-speed USB interface and the program Gold Wave http://www.goldwave.com. The recordings included individuals with cardiac structural disease as well as recordings from normal individuals and from individuals with innocent heart murmurs. Digital Subtraction Analysis of the signal was performed using a custom computer program called Murmurgram. In essence, this program subtracts the recorded sound from two adjacent cardiac cycles to produce a difference signal, herein called a "murmurgram". Other software used included Spectrogram (Version 16), GoldWave (Version 5.55) as well as custom MATLAB code. Our preliminary data is presented as a series of eight cases. These cases show how advanced signal processing techniques can be used to separate heart sounds from murmurs. Note that these results are preliminary in that normal ranges for obtained test results have not yet been established. Cardiac murmurs can be separated from underlying deterministic heart sounds using DSP. DSP has the potential to become a reliable and economical new diagnostic approach to screening for structural heart disease. However, DSP must be further evaluated in a large series of patients with well-characterized pathology to determine its clinical potential.

  5. Anatomic and functional imaging of congenital heart disease with digital subtraction angiography

    SciTech Connect

    Buonocore, E.; Pavlicek, W.; Modic, M.T.; Meaney, T.F.; O'Donovan, P.B.; Grossman, L.B.; Moodie, D.S.; Yiannikas, J.

    1983-06-01

    Digital subtraction angiography (DSA) of the heart was performed in 54 patients for the evaluation of congenital heart diagnostic images and accurate physiologic shunt data that compared favorably with catheter angiography and nuclear medicine studies. Retrospective analysis of this series of patients indicated that DSA studies contributed sufficient informantion to shorten significantly or modify cardiac catheterization in 85% (79/93) of the defects that were identified. Interatrial septal defects were particularly well diagnosed, with identification occurring in 10 of 10 cases, wheseas intraventricular septal defects were identified in only 6 of 9 patients. Evaluation of postsurgical patients was accurate in 19 of 20 cases.

  6. [Clear visualization of the tracheobronchial tree in complex congenital heart disease using digital subtraction fluorography].

    PubMed

    Shiba, N; Kimura, K; Ohta, M; Naito, H; Saito, H; Takamiya, M; Kishimoto, H; Kamiya, T

    1990-02-01

    We knew that digital subtraction fluorography (DSF) could clearly visualize the tracheobronchial tree by the respiratory movement. We applied DSF for 54 patients of complex congenital heart disease. In the visualization of the tracheobronchial tree, DSF was significantly superior as compared with the plain chest radiography (p less than 0.01). As this method needs to anesthetize patients to suppress their body movements, there might be some limitation to apply it for routine diagnostic workup. However, noninvasiveness and readiness of diagnosis justifies this method as an optional examination for confirming thoracic situs of complex congenital heart disease.

  7. Cerebrovascular disease: evaluation with transbrachial intraarterial digital subtraction angiography using a 4-F catheter.

    PubMed

    Hicks, M E; Kreipke, D L; Becker, G J; Edwards, M K; Holden, R W; Jackson, V P; Bendick, P J; Kuehn, D S

    1986-11-01

    Three hundred sixty-one patients underwent intraarterial digital subtraction angiography for definite or probable occlusive vascular disease of the carotid arteries. Examinations were performed with 65-cm-long, 4-F aortic catheters. A transbrachial approach was used. Images were good or excellent in nearly all cases. No postprocedural neurologic deficits or hematomas occurred. Permanent pulse deficit occurred in two patients, and temporary deficit occurred in three patients, an improvement over the frequency found in previous transbrachial series using 6-8-F catheters. While these results establish the efficacy of this technique, they also indicate a possible greater relative safety in men than in women.

  8. Digital subtraction angiography of the pulmonary arteries for the diagnosis of pulmonary embolism

    SciTech Connect

    Ludwig, J.W.; Verhoeven, L.A.J.; Kersbergen, J.J.; Overtoom, T.T.C.

    1983-06-01

    A comparative study of radionuclide scanning (perfusion studies in all 18 patients and ventilation studies in 9) and digital subtraction angiography (DSA) was performed in 18 patients with suspected pulmonary thromboembolism. In 17 patients good visualization of the arteries was obtained with DSA; 10 of these patients had no pre-existing lung disease, and 7 had chronic obstructive pulmonary disease (COPD). The information provided by DSA in this small group was equal to or better than that of scintigraphy, especially in patients with COPD, and the reliability of DSA was superior to that of the radionuclide scintigraphy. Methods for preventing motion artifacts with DSA are also described.

  9. How number line estimation skills relate to neural activations in single digit subtraction problems.

    PubMed

    Berteletti, I; Man, G; Booth, J R

    2015-02-15

    The Number Line (NL) task requires judging the relative numerical magnitude of a number and estimating its value spatially on a continuous line. Children's skill on this task has been shown to correlate with and predict future mathematical competence. Neurofunctionally, this task has been shown to rely on brain regions involved in numerical processing. However, there is no direct evidence that performance on the NL task is related to brain areas recruited during arithmetical processing and that these areas are domain-specific to numerical processing. In this study, we test whether 8- to 14-year-old's behavioral performance on the NL task is related to fMRI activation during small and large single-digit subtraction problems. Domain-specific areas for numerical processing were independently localized through a numerosity judgment task. Results show a direct relation between NL estimation performance and the amount of the activation in key areas for arithmetical processing. Better NL estimators showed a larger problem size effect than poorer NL estimators in numerical magnitude (i.e., intraparietal sulcus) and visuospatial areas (i.e., posterior superior parietal lobules), marked by less activation for small problems. In addition, the direction of the activation with problem size within the IPS was associated with differences in accuracies for small subtraction problems. This study is the first to show that performance in the NL task, i.e. estimating the spatial position of a number on an interval, correlates with brain activity observed during single-digit subtraction problem in regions thought to be involved in numerical magnitude and spatial processes.

  10. Assessment of three methods of geometric image reconstruction for digital subtraction radiography.

    PubMed

    Queiroz, Polyane M; Oliveira, Matheus L; Tanaka, Jefferson L O; Soares, Milton G; Haiter-Neto, Francisco; Ono, Evelise

    To evaluate three methods of geometric image reconstruction for digital subtraction radiography (DSR). Digital periapical radiographs were acquired of 24 teeth with the X-ray tube at 6 different geometric configurations of vertical (V) and horizontal (H) angles: V0°H0°, V0°H10°, V10°H0°, V10°H10°, V20°H0° and V20°H10°. All 144 images were registered in pairs (Group V0°H0° + 1 of the 6 groups) 3 times by using the Emago(®) (Oral Diagnostic Systems, Amsterdam, Netherlands) with manual selection and Regeemy with manual and automatic selections. After geometric reconstruction on the two software applications under different modes of selection, all images were subtracted and the standard deviation of grey values was obtained as a measure of image noise. All measurements were repeated after 15 days to evaluate the method error. Values of image noise were statistically analyzed by one-way ANOVA for differences between methods and between projection angles, followed by Tukey's test at a level of significance of 5%. Significant differences were found between most of the projection angles for the three reconstruction methods. Image subtraction after manual selection-based reconstruction on Regeemy presented the lowest values of image noise, except on group V0°H0°. The groups V10°H0° and V20°H0° were not significantly different between the manual selection-based reconstruction in Regeemy and automatic selection-based reconstruction in Regeemy methods. The Regeemy software on manual mode revealed better quality of geometric image reconstruction for DSR than the Regeemy on automatic mode and the Emago on manual mode, when the radiographic images were obtained at V and H angles used in the present investigation.

  11. Intravenous Angiocardiography Using Digital Image Processing: Experience With Axial Projections In Normal Pigs And In Pigs With Experimentally Generated Left-To-Right Shunts

    NASA Astrophysics Data System (ADS)

    Bogren, Hugo G.; Bursch, Joachim H.; Brennecke, Rudiger; Heintzen, Paul H.

    1981-11-01

    Computerized digitization and processing of roentgen video images recorded at a rate of 50 per second was tested in intravenous angiocardiography in normal pigs weighing 15 to 20 kg. Roentgen video images were recorded in the 4-chamber view obtained by 30-35 degrees caudocranial angulation of the x-ray tube and 50-60 degrees LAO obliquity in the pig. Significant contrast enhancement was obtained through ECG-gated background subtraction and rescaling after integration of multiple background as well as contrast images. Occasionally, histogram equalization was used to further enhance contrast. To study temporal changes in cardiac motion, time parameter extraction or functional imaging was applied as well. The left and right heart were well visualized after intravenous injection of 1/3-1 cc. 76% Urografin per kg. bodyweight. Special purpose processing like subtraction of the end systolic phase from the end diastolic in the left and right ventricles as well as subtraction of the right ventricular phase from the left ventricular phase was also performed. If the left ventricular end systolic phase was subtracted from the end diastolic, most of the left atrium was also subtracted whereby the left ventricle was seen without continuity or superimposition of the left atrium. Experimentally generated ventricular and atrial septal defects as well as patent ductus arteriosus could be detected using the described technique. The results of the animal experiments became the basis for subsequent applications in children with congenital heart disease.

  12. Analytical optimization of digital subtraction mammography with contrast medium using a commercial unit

    SciTech Connect

    Rosado-Mendez, I.; Palma, B. A.; Brandan, M. E.

    2008-12-15

    Contrast-medium-enhanced digital mammography (CEDM) is an image subtraction technique which might help unmasking lesions embedded in very dense breasts. Previous works have stated the feasibility of CEDM and the imperative need of radiological optimization. This work presents an extension of a former analytical formalism to predict contrast-to-noise ratio (CNR) in subtracted mammograms. The goal is to optimize radiological parameters available in a clinical mammographic unit (x-ray tube anode/filter combination, voltage, and loading) by maximizing CNR and minimizing total mean glandular dose (D{sub gT}), simulating the experimental application of an iodine-based contrast medium and the image subtraction under dual-energy nontemporal, and single- or dual-energy temporal modalities. Total breast-entrance air kerma is limited to a fixed 8.76 mGy (1 R, similar to screening studies). Mathematical expressions obtained from the formalism are evaluated using computed mammographic x-ray spectra attenuated by an adipose/glandular breast containing an elongated structure filled with an iodinated solution in various concentrations. A systematic study of contrast, its associated variance, and CNR for different spectral combinations is performed, concluding in the proposal of optimum x-ray spectra. The linearity between contrast in subtracted images and iodine mass thickness is proven, including the determination of iodine visualization limits based on Rose's detection criterion. Finally, total breast-entrance air kerma is distributed between both images in various proportions in order to maximize the figure of merit CNR{sup 2}/D{sub gT}. Predicted results indicate the advantage of temporal subtraction (either single- or dual-energy modalities) with optimum parameters corresponding to high-voltage, strongly hardened Rh/Rh spectra. For temporal techniques, CNR was found to depend mostly on the energy of the iodinated image, and thus reduction in D{sub gT} could be achieved if the

  13. The Reduction Of Motion Artifacts In Digital Subtraction Angiography By Geometrical Image Transformation

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, J. Michael; Pickens, David R.; Mandava, Venkateswara R.; Grefenstette, John J.

    1988-06-01

    In the diagnosis of arteriosclerosis, radio-opaque dye is injected into the interior of the arteries to make them visible. Because of its increased contrast sensitivity, digital subtraction angiography has the potential for providing diagnostic images of arteries with reduced dye volumes. In the conventional technique, a mask image, acquired before the introduction of the dye, is subtracted from the contrast image, acquired after the dye is introduced, to produce a difference image in which only the dye in the arteries is visible. The usefulness of this technique has been severely limited by the image degradation caused by patient motion during image acquisition. This motion produces artifacts in the difference image that obscure the arteries. One technique for dealing with this problem is to reduce the degradation by means of image registration. The registration is carried out by means of a geometrical transformation of the mask image before subtraction so that it is in registration with the contrast image. This paper describes our technique for determining an optimal transformation. We employ a one-to-one elastic mapping and the Jacobian of that mapping to produce a geometrical image transformation. We choose a parameterized class of such mappings and use a heuristic search algorithm to optimize the parameters to minimize the severity of the motion artifacts. To increase the speed of the optimization process we use a statistical image comparison technique that provides a quick approximate evaluation of each image transformation. We present the experimental results of the application of our registration system to mask-contrast pairs, for images acquired from a specially designed phantom (described in a companion paper), and for clinical images.

  14. Quantitative digital subtraction radiography for assessment of bone density changes following periodontal guided tissue regeneration.

    PubMed

    Christgau, M; Wenzel, A; Hiller, K A; Schmalz, G

    1996-01-01

    The quantitative assessment of alveolar bone density changes in periodontal defects following guided tissue regeneration (GTR). Twelve patients with 30 intrabony lesions and 16 furcation defects took part. Standardized radiographic and clinical examinations were carried out immediately before and then 5 and 13 months after surgery. Intra-oral radiographs were evaluated by means of digital subtraction radiography (DSR). Within the subtraction images, a window ('experimental region') was defined covering the visible density changes in the defect area. Background noise was measured by using a similarly sized window ('control region') located in an area not affected by GTR. Bone density changes were quantitatively evaluated by calculation of the mean, standard deviation and maximum and minimum values of the grey-level histogram within these windows. DSR revealed significant bone density gain after GTR in intrabony and furcation defects. While a continuous increase was observed over the 13 month period in intrabony defects, changes in furcation defects occurred mostly in the 5-13 month period. Clinically, a distinct vertical and horizontal attachment gain was found. The correlation coefficients between changes in radiographic density and clinical parameters were low, indicating a difference in the information obtained by the two diagnostic methods. Quantitative DSR is a valuable, non-invasive, objective method to obtain information on density changes in intrabony and furcation defects treated by GTR. However, a full assessment of soft and hard tissue changes requires both clinical evaluation and DSR.

  15. Novel method for digital subtraction of tagged stool in virtual colonoscopy

    NASA Astrophysics Data System (ADS)

    Guendel, Lutz; Suehling, Michael; Eckert, Helmut

    2008-03-01

    Colon cancer is one of the most frequent causes of death. CT colonography is a novel method for the detection of polyps and early cancer. The general principle of CT colonography includes a cathartic bowel preparation. The resulting discomfort for patients leads to limited patient acceptance and therefore to limited cancer detection rates. Reduced bowel preparation, techniques for stool tagging, and electronic cleansing, however, improve the acceptance rates. Hereby, the high density of oral contrast material highlights residual stool and can be digitally removed. Known subtraction methods cause artifacts: additional 3D objects are introduced and small bowel folds are perforated. We propose a new algorithm that is based on the 2 nd derivative of the image data using the Hessian matrix and the following principal axis transform to detect tiny folds which shall not be subtracted together with tagged stool found by a thresholding method. Since the stool is usually not homogenously tagged with contrast media a detection algorithm for island-like structures is incorporated. The interfaces of air-stool level and colon wall are detected by a 3-dimensional difference of Gaussian module. A 3-dimensional filter smoothes the transitions between removed stool and colon tissue. We evaluated the efficacy of the new algorithm with 10 patient data sets. The results showed no introduced artificial objects and no perforated folds. The artifacts at the air-stool and colon tissue-stool transitions are considerably reduced compared to those known from the literature.

  16. Intra-arterial digital subtraction angiogrpahy: comparison with conventional hepatic arteriography

    SciTech Connect

    Flannigan, B.D.; Gomes, A.S.; Stambuk, E.C.; Lois, J.F.; Pais, S.O.

    1983-07-01

    To evaluate the efficacy of arterial digital subtraction angiography (DSA), 28 patients with a variety of hepatic lesions underwent intra-arterial DSA immediately following conventional celiac or hepatic arteriography. Thirty-one studies were obtained and the results of DSA were compared with the conventional arteriograms. DSA showed good visualization of the arteries in the early arterial phase of the examination. The late arterial phase was better evaluated on conventional arteriograms due to the decreased spatial resolution of DSA. Arterial DSA was most useful in the evaluation of the parenchyma of the liver; the use of remasking techniques allowed improved visualization of hepatic lesions, particularly in the left lobe of the liver. It is concluded that arterial DSA is useful in hepatic imaging and may supplant conventional hepatic arteriography as the technology improves.

  17. Flow measurements with digital subtraction densitometry in a steady flow experimental model.

    PubMed

    Mygind, M; Engell, L; Mygind, T

    1995-07-01

    Computerized densitometry was applied on digital subtraction series for measuring flow rates, 600 to 2,000 ml/min, in model experiments, using contrast medium as indicator substance. A total of 962 measurements were performed, employing the Stewart-Hamilton dilution technique, as well as direct measurements of velocity of the indicator bolus between 2 measuring sites. Results with the dilution technique were closely correlated with true values, but slightly lower (mean 8%), presumably because of sedimentation of contrast medium. Measurements based on bolus velocity were most accurate when the bolus passage was defined by points near the gravity line of the area under the concentration curve. Use of more easily identified curve points, e.g. the time of curve maximum, tended to yield too high values due to flow laminarity with a high-velocity leading edge of the indicator. Variation in repeated measurements on any single image series was attributed to the low sampling rate.

  18. All-optical digital logic: Full addition or subtraction on a three-state system

    SciTech Connect

    Remacle, F.; Levine, R. D.

    2006-03-15

    Stimulated Raman adiabatic passage (STIRAP) is a well-studied pump-probe control scheme for manipulating the population of quantum states of atoms or molecules. By encoding the digits to be operated on as 'on' or 'off' laser input signals we show how STIRAP can be used to implement a finite-state logic machine. The physical conditions required for an effective STIRAP operation are related to the physical conditions expected for a logic machine. In particular, a condition is derived on the mean number of photons that represent an on pulse. A finite-state machine computes Boolean expressions that depend both on the input and on the present state of the machine. With two input signals we show how to implement a full adder where the carry-in digit is stored in the state of the machine. Furthermore, we show that it is possible to store the carry-out digit as the next state and thereby return the machine to a state ready for the next full addition. Such a machine operates as a cyclical full adder. We further show how this full adder can equally well be operated as a full subtractor. To the best of our knowledge this is the first example of a nanosized system that implements a full subtraction.

  19. Effectiveness of digital subtraction radiography in detecting artificially created osteophytes and erosions in the temporomandibular joint.

    PubMed

    Demirturk Kocasarac, Husniye; Celenk, Peruze

    2017-06-01

    Erosions and osteophytes are radiographic characteristics that are found in different stages of temporomandibular joint (TMJ) osteoarthritis. This study assessed the effectiveness of digital subtraction radiography (DSR) in diagnosing simulated osteophytes and erosions in the TMJ. Five intact, dry human skulls were used to assess the effectiveness of DSR in detecting osteophytes. Four cortical bone chips of varying thicknesses (0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm) were placed at the medial, central, and lateral aspects of the condyle anterior surface. Two defects of varying depth (1.0 mm and 1.5 mm) were created on the lateral, central, and medial poles of the condyles of 2 skulls to simulate erosions. Panoramic images of the condyles were acquired before and after artificially creating the changes. Digital subtraction was performed with Emago dental image archiving software. Five observers familiar with the interpretation of TMJ radiographs evaluated the images. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic accuracy of the imaging methods. The area under the ROC curve (Az) value for the overall diagnostic accuracy of DSR in detecting osteophytic changes was 0.931. The Az value for the overall diagnostic accuracy of panoramic imaging was 0.695. The accuracy of DSR in detecting erosive changes was 0.854 and 0.696 for panoramic imaging. DSR was remarkably more accurate than panoramic imaging in detecting simulated osteophytic and erosive changes. The accuracy of panoramic imaging in detecting degenerative changes was significantly lower than the accuracy of DSR (P<.05). DSR improved the accuracy of detection using panoramic images.

  20. Evaluation of chronic periapical lesions by digital subtraction radiography by using Adobe Photoshop CS: a technical report.

    PubMed

    Carvalho, Fabiola B; Gonçalves, Marcelo; Tanomaru-Filho, Mário

    2007-04-01

    The purpose of this study was to describe a new technique by using Adobe Photoshop CS (San Jose, CA) image-analysis software to evaluate the radiographic changes of chronic periapical lesions after root canal treatment by digital subtraction radiography. Thirteen upper anterior human teeth with pulp necrosis and radiographic image of chronic periapical lesion were endodontically treated and radiographed 0, 2, 4, and 6 months after root canal treatment by using a film holder. The radiographic films were automatically developed and digitized. The radiographic images taken 0, 2, 4, and 6 months after root canal therapy were submitted to digital subtraction in pairs (0 and 2 months, 2 and 4 months, and 4 and 6 months) choosing "image," "calculation," "subtract," and "new document" tools from Adobe Photoshop CS image-analysis software toolbar. The resulting images showed areas of periapical healing in all cases. According to this methodology, the healing or expansion of periapical lesions can be evaluated by means of digital subtraction radiography by using Adobe Photoshop CS software.

  1. Conceptual design of an 8 Tesla superconducting wiggler for a dedicated digital subtraction angiography source

    SciTech Connect

    Blum, E.B.

    1993-09-01

    One of the most important techniques used to diagnose heart disease is coronary angiography. Coronary angiography is only used when it is absolutely essential because of the risk of fatalities and other serious complications arising from the insertion of the catheter. The technique also exposes the patients to large amounts of x-rays. Research, begun at SSRL and continued on the X17 beam line at NSLS, demonstrated the feasibility of imaging human coronary arteries following venous injection of the contrast agent. The technique, caged digital subtraction angiography (DSA), uses two monochromatic beams of x-rays, one slightly above and one slightly below the iodine K absorption edge (33.169 KeV) to collect simultaneous images. When the two images are subtracted, the contrast agent, contained primarily in the blood vessels, is revealed and the background that is common to both images is suppressed. The images must be collected during a single heartbeat to avoid blurring from motion of the blood vessels. Conventional x-ray sources are too weak to provide the intense flux that is required in the narrow energy bandwidth of the beams. Only the most powerful synchrotron radiation beams from wiggler magnet sources can provide the intensity required in the short exposure time. Although DSA experiments have shown promise, they have been conducted at large, research synchrotron radiation facilities. A small, dedicated source will be needed before DSA can be used as a standard medical procedure. Such x-ray sources as laser backscattering, Cherenkov radiation, parametric x-radiation, and channeling radiation have been suggested for hospital based DSA sources but none of them appear to produce enough flux to be useful. Barring the discovery of a new source of intense x-rays, only synchrotron radiation seems to meet the requirements for DSA. This report briefly describes the preliminary design of a high field, superconducting wiggler magnet that can be used as a DSA source.

  2. Improved Visualization of Intracranial Vessels with Intraoperative Coregistration of Rotational Digital Subtraction Angiography and Intraoperative 3D Ultrasound

    PubMed Central

    Podlesek, Dino; Meyer, Tobias; Morgenstern, Ute; Schackert, Gabriele; Kirsch, Matthias

    2015-01-01

    Introduction Ultrasound can visualize and update the vessel status in real time during cerebral vascular surgery. We studied the depiction of parent vessels and aneurysms with a high-resolution 3D intraoperative ultrasound imaging system during aneurysm clipping using rotational digital subtraction angiography as a reference. Methods We analyzed 3D intraoperative ultrasound in 39 patients with cerebral aneurysms to visualize the aneurysm intraoperatively and the nearby vascular tree before and after clipping. Simultaneous coregistration of preoperative subtraction angiography data with 3D intraoperative ultrasound was performed to verify the anatomical assignment. Results Intraoperative ultrasound detected 35 of 43 aneurysms (81%) in 39 patients. Thirty-nine intraoperative ultrasound measurements were matched with rotational digital subtraction angiography and were successfully reconstructed during the procedure. In 7 patients, the aneurysm was partially visualized by 3D-ioUS or was not in field of view. Post-clipping intraoperative ultrasound was obtained in 26 and successfully reconstructed in 18 patients (69%) despite clip related artefacts. The overlap between 3D-ioUS aneurysm volume and preoperative rDSA aneurysm volume resulted in a mean accuracy of 0.71 (Dice coefficient). Conclusions Intraoperative coregistration of 3D intraoperative ultrasound data with preoperative rotational digital subtraction angiography is possible with high accuracy. It allows the immediate visualization of vessels beyond the microscopic field, as well as parallel assessment of blood velocity, aneurysm and vascular tree configuration. Although spatial resolution is lower than for standard angiography, the method provides an excellent vascular overview, advantageous interpretation of 3D-ioUS and immediate intraoperative feedback of the vascular status. A prerequisite for understanding vascular intraoperative ultrasound is image quality and a successful match with preoperative

  3. Causal role of the posterior parietal cortex for two-digit mental subtraction and addition: A repetitive TMS study.

    PubMed

    Montefinese, Maria; Turco, Cristina; Piccione, Francesco; Semenza, Carlo

    2017-07-15

    Although parietal areas of the left hemisphere are known to be involved in simple mental calculation, the possible role of the homologue areas of the right hemisphere in mental complex calculation remains debated. In the present study, we tested the causal role of the posterior parietal cortex of both hemispheres in two-digit mental addition and subtraction by means of neuronavigated repetitive TMS (rTMS), investigating possible hemispheric asymmetries in specific parietal areas. In particular, we performed two rTMS experiments, which differed only for the target sites stimulated, on independent samples of participants. rTMS was delivered over the horizontal and ventral portions of the intraparietal sulcus (HIPS and VIPS, respectively) of each hemisphere in Experiment 1, and over the angular and supramarginal gyri (ANG and SMG, respectively) of each hemisphere in Experiment 2. First, we found that each cerebral area of the posterior parietal cortex is involved to some degree in the two-digit addition and subtraction. Second, in Experiment 1, we found a stronger pattern of hemispheric asymmetry for the involvement of HIPS in addition compared to subtraction. In particular, results showed a greater involvement of the right HIPS than the left one for addition. Moreover, we found less asymmetry for the VIPS. Taken together, these results suggest that two-digit mental addition is more strongly associated with the use of a spatial mapping compared to subtraction. In support of this view, in Experiment 2, a greater role of left and right ANG was found for addition needed in verbal processing of numbers and in visuospatial attention processes, respectively. We also revealed a greater involvement of the bilateral SMG in two-digit mental subtraction, in response to greater working memory load required to solve this latter operation compared to addition. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Nonrigid Image Registration in Digital Subtraction Angiography Using Multilevel B-Spline

    PubMed Central

    2013-01-01

    We address the problem of motion artifact reduction in digital subtraction angiography (DSA) using image registration techniques. Most of registration algorithms proposed for application in DSA, have been designed for peripheral and cerebral angiography images in which we mainly deal with global rigid motions. These algorithms did not yield good results when applied to coronary angiography images because of complex nonrigid motions that exist in this type of angiography images. Multiresolution and iterative algorithms are proposed to cope with this problem, but these algorithms are associated with high computational cost which makes them not acceptable for real-time clinical applications. In this paper we propose a nonrigid image registration algorithm for coronary angiography images that is significantly faster than multiresolution and iterative blocking methods and outperforms competing algorithms evaluated on the same data sets. This algorithm is based on a sparse set of matched feature point pairs and the elastic registration is performed by means of multilevel B-spline image warping. Experimental results with several clinical data sets demonstrate the effectiveness of our approach. PMID:23971026

  5. K-edge digital subtraction imaging with dichromatic x-ray sources: SNR and dose studies

    NASA Astrophysics Data System (ADS)

    Sarnelli, A.; Elleaume, H.; Taibi, A.; Gambaccini, M.; Bravin, A.

    2006-09-01

    The aim of the present work is to analytically evaluate the signal to noise ratio (SNR) and the delivered dose in K-edge digital subtraction imaging (KES) using two types of x-ray sources: a monochromatic x-ray source (available at synchrotron radiation facilities and considered as gold standard) and a quasi-monochromatic compact source. The energy separation ΔE between the two monochromatic beams is 1 keV and 4 keV for the two sources, respectively. The evaluation has been performed for both radiography and computed tomography. Different geometries have been studied to mimic clinical situations. In mammography, a pathology perfused by a contrast agent has been modelled; in angiography, a vessel superimposed to a ventricle or a stand-alone artery stenosis has been studied. The SNR and the skin dose have been calculated as a function of the detail diameter, the contrast agent (iodine and gadolinium), and its concentration in the tissues. Results show that for ΔE = 4 keV a slightly higher delivered dose is required to obtain the same SNR with respect to ΔE < 1 keV. A similar study has been performed for KES-CT. Computer simulations of CT images performed with Snark software are shown to validate the analytical calculations.

  6. [Digital subtraction angiography with carbon dioxide in severe arterial ischemia and allergy to iodinated compounds].

    PubMed

    Calvo Cascallo, J; Mundi Salvadó, N; Cardona Fontanet, M

    1993-01-01

    When in some selected patients, a direct arterial surgery (DAS) procedure or an endoluminal surgery (ES) are required for a chronic arterial ischemia (III or IV degrees), and an arteriography with contrast is absolutely contraindicated (because of severe renal failure without hemodialysis program or a severe congestive heart failure or a hyperthyroidism or a seriously demonstrated hypersensibility against the contrast agents); an angiography by digital subtraction with carbon dioxide (DIVAS-CO2) is indicated. This technique provides good quality images with minimal risks for the patient and an adequate study for ulterior treatment. We report a case of a 67-years-old woman, with diabetes-II, ischemic cardiopathy, arterial hypertension and a demonstrated hypersensibility against the iodide compounds. The patient was admitted because of a chronic ischemia (IV degree) with ischemic ulcerations on some fingers from the left foot. High doses of analgesic drugs were needed. Because the hypersensibility against the iodide compounds, an angiography with CO2 was carried out. The good quality images provided by this technique showed the factibility of a revascularization.

  7. Increasing Efficacy of Thrombectomy by Using Digital Subtraction Angiography to Confirm Stent Retriever Clot Integration

    PubMed Central

    Simon, Scott; Cooke, Jonathon

    2016-01-01

    Physicians performing thrombectomy for acute stroke have had increasing success as thrombectomy-specific devices have continued to evolve. As the devices evolve, so too must the techniques. The current generation of stent retriever thrombectomy devices requires five minutes of dwell time, regardless of the particularities of the case. We have noticed the presence of flow through the stent immediately prior to removal portends a lower chance of successful thrombus retrieval than when no flow is seen, regardless of dwell time. We hypothesize that interventionalists can use the presence or absence of flow to predict adequacy of seating time and decrease the number of deployments per case. This could significantly decrease time to recanalization by avoiding time-consuming, unsuccessful pulls. This is a technical report of a few cases of stent retriever thrombectomy. We propose using post-deployment digital subtraction angiography to confirm thrombus-device integration and increase the chance of thrombus removal. PMID:27182473

  8. A LabVIEW Platform for Preclinical Imaging Using Digital Subtraction Angiography and Micro-CT.

    PubMed

    Badea, Cristian T; Hedlund, Laurence W; Johnson, G Allan

    2013-01-01

    CT and digital subtraction angiography (DSA) are ubiquitous in the clinic. Their preclinical equivalents are valuable imaging methods for studying disease models and treatment. We have developed a dual source/detector X-ray imaging system that we have used for both micro-CT and DSA studies in rodents. The control of such a complex imaging system requires substantial software development for which we use the graphical language LabVIEW (National Instruments, Austin, TX, USA). This paper focuses on a LabVIEW platform that we have developed to enable anatomical and functional imaging with micro-CT and DSA. Our LabVIEW applications integrate and control all the elements of our system including a dual source/detector X-ray system, a mechanical ventilator, a physiological monitor, and a power microinjector for the vascular delivery of X-ray contrast agents. Various applications allow cardiac- and respiratory-gated acquisitions for both DSA and micro-CT studies. Our results illustrate the application of DSA for cardiopulmonary studies and vascular imaging of the liver and coronary arteries. We also show how DSA can be used for functional imaging of the kidney. Finally, the power of 4D micro-CT imaging using both prospective and retrospective gating is shown for cardiac imaging.

  9. Comparison of CT angiography and digital subtraction angiography in the diagnosis of aortic coarctation.

    PubMed

    Miabi, Zinat; Pourfathi, Hojjat; Midia, Mehran; Midia, Ramin; Parvizi, Rezayat

    2011-01-01

    There are several methods for the diagnosis and evaluation of coarctation of the aorta. Digital Subtraction Angiography (DSA) is the standard detection method, though it entails complications and side-effects. The aim of the present study was to compare Computed Tomography (CT) angiography with DSA for diagnosing aortic coarctation. We performed a cross-sectional study of 15 patients (11 males and four females aged between two and 30 years) referred to Tabriz Shahid Madani Hospital and Imaging Center between August 2005 and February 2006 with suspected aortic coarctation. All patients were subjected to DSA and CT angiography for diagnosis of aortic coarctation. The mean age of the patients was 14.6 years; 11 were male (74.4%) and four (26.6%) were female. The DSA and CT angiography results were comparable in all patients in terms of diagnosis and the detection of complications, particularly cardiovascular complications. However, CT angiography was less time-consuming to perform than DSA (p < 0.0001). In conclusion, CT angiography, comparableto DSA, diagnosed coarctation of aorta in all the patients. However, CT angiography is a non-invasive, cost effective procedure that takes significantly less time to carry out than DSA. Therefore, CT angiography is recommended as an appropriate method for diagnosing the coarctation of aorta.

  10. Accurate registration of coronary arteries for volumetric CT digital subtraction angiography

    NASA Astrophysics Data System (ADS)

    Razeto, Marco; Matthews, James; Masood, Saad; Steel, Jill; Arakita, Kazumasa

    2013-03-01

    In the diagnosis of coronary artery disease with coronary computed tomography angiography, accurate evaluation remains challenging in the presence of calcifications or stents. Volumetric CT Digital Subtraction Angiography is a novel method that may become a powerful tool to overcome these limitations. However, precise registration of structures is essential, as even small misalignments can produce striking and disruptive bright and dark artefacts. Moreover, for clinical acceptance, the tool should require minimal user interaction and fast turnaround, thereby raising several challenges. In this paper we address the problem with a registration method based on a global non- rigid step, followed by local rigid refinement. In our quantitative analysis based on 10 datasets, each consisting of a pair of pre- and post-contrast scans of the same patient, we achieve an average Target Registration Error of 0.45 mm. Runtimes are less than 90 seconds for the global step, while each local refinement takes less than 15 seconds to run. Initial clinical evaluation shows good results in cases of moderate calcification, and indicates that around 50% of severely calcified and previously non-interpretable cases have been made interpretable by application of our method.

  11. Failing Hemodialysis Arteriovenous Fistula and Percutaneous Treatment: Imaging with CT, MRI and Digital Subtraction Angiography

    SciTech Connect

    Cavagna, Enrico; D'Andrea, Paolo; Schiavon, Francesco; Tarroni, Giovanni

    2000-07-15

    Purpose: To evaluate failing hemodialysis arteriovenous fistulas with helical CT angiography (CTA), MR angiography (MRA), and digital subtraction angiography (DSA), and to compare the efficacy of the three techniques in detecting the number, location, grade, and extent of stenoses and in assessing the technical results of percutaneous transluminal angioplasty (PTA) and stenting.Methods: Thirteen patients with Brescia-Cimino arteriovenous fistula malfunction underwent MRA and CTA of the fistula and, within 1 week, DSA. A total of 11 PTAs were performed; in three cases an MR-compatible stent was placed. DSA served as the gold standard for comparison in all patients. The presence, site, and number of stenoses or occlusions and the technical results of percutaneous procedures were assessed with DSA, CTA, and MRA.Results: MRA underestimated a single stenosis in one patient; CTA and MRA did not overestimate any stenosis. Significant artifacts related to stent geometry and/or underlying metal were seen in MRA sequences in two cases.Conclusions: CT and MRI can provide information regarding the degree of vascular impairment, helping to stratify patients into those who can have PTA (single or multiple stenoses) versus those who require an operative procedure (occlusion). Conventional angiography can be reserved for candidates for percutaneous intervention.

  12. Analysis of the venous channel within the clivus using multidetector computed tomography digital subtraction venography.

    PubMed

    Mizutani, Katsuhiro; Toda, Masahiro; Kurasawa, Jun; Akiyama, Takenori; Fujiwara, Hirokazu; Jinzaki, Masahiro; Yoshida, Kazunari

    2017-03-01

    Although neuroradiologists and skull base neurosurgeons are aware of the existence of veins within the clivus, such vessels have seldom been described in the literature. The aim of the present study is to elucidate the detailed venous structure of the clivus. Computed tomography digital subtraction venography (CT-DSV) images of 50 unruptured aneurysm cases were examined retrospectively. Eighteen emissary veins were identified in 14 (28.0%) cases. A half of the emissary veins connected the inferior petrosal sinus with the inferior petro-occipital vein (IPOV) in the middle clivus. The clival diploic vein (CDV) was identified in 14.0% of cases, 42.9% of which had the clivus of the presellar type. The CDV was connected to the posterior intercavernous sinus or the rostral end of the basilar plexus superiorly, and was connected to the IPOV, anterior condylar vein, marginal sinus, or the anterior condylar confluence. The CDV provides collateral channels between the cavernous sinus and the internal jugular vein and the inferior petrosal sinus and the IPOV. Understanding of the emissary veins in the clivus and the CDV is valuable for skull base surgery, especially for endonasal endoscopic skull base procedures.

  13. Remapping of digital subtraction angiography on a standard fluoroscopy system using 2D-3D registration

    NASA Astrophysics Data System (ADS)

    Alhrishy, Mazen G.; Varnavas, Andreas; Guyot, Alexis; Carrell, Tom; King, Andrew; Penney, Graeme

    2015-03-01

    Fluoroscopy-guided endovascular interventions are being performing for more and more complex cases with longer screening times. However, X-ray is much better at visualizing interventional devices and dense structures compared to vasculature. To visualise vasculature, angiography screening is essential but requires the use of iodinated contrast medium (ICM) which is nephrotoxic. Acute kidney injury is the main life-threatening complication of ICM. Digital subtraction angiography (DSA) is also often a major contributor to overall patient radiation dose (81% reported). Furthermore, a DSA image is only valid for the current interventional view and not the new view once the C-arm is moved. In this paper, we propose the use of 2D-3D image registration between intraoperative images and the preoperative CT volume to facilitate DSA remapping using a standard fluoroscopy system. This allows repeated ICM-free DSA and has the potential to enable a reduction in ICM usage and radiation dose. Experiments were carried out using 9 clinical datasets. In total, 41 DSA images were remapped. For each dataset, the maximum and averaged remapping accuracy error were calculated and presented. Numerical results showed an overall averaged error of 2.50 mm, with 7 patients scoring averaged errors < 3 mm and 2 patients < 6 mm.

  14. Patient radiation dose from computed tomography angiography and digital subtraction angiography of the brain

    NASA Astrophysics Data System (ADS)

    Netwong, Y.; Krisanachinda, A.

    2016-03-01

    The 64-row multidetector computed tomography angiography (64-MDCTA) provides vascular image quality of the brain similar to digital subtraction angiography (DSA), but the effective dose of CTA is lower than DSA studied in phantom. The purpose of this study is to evaluate the effective dose from 64-MDCTA and DSA. Effective dose (according to ICRP 103) from 64-MDCTA and DSA flat panel detector for cerebral vessels examination of the brain using standard protocols as recommended by the manufacturer was calculated for 30 cases of MDCTA (15 male and 15 female).The mean patient age was 49.5 (23-89) yrs. 30 cases of DSA (14 male and 16 female), the mean patient age was 46.8 (21-81) yrs. For CTA, the mean effective dose was 3.7 (2.82- 5.19) mSv. For DSA, the mean effective dose was 5.78 (3.3-10.06) mSv. The effective dose of CTA depends on the scanning protocol and scan length. Low tube current can reduce patient dose whereas the number of exposures and number of series in 3D rotational angiography (3D RA) resulted in increasing effective dose in DSA patients.

  15. In Vivo Small Animal Imaging using Micro-CT and Digital Subtraction Angiography

    PubMed Central

    Badea, C.T.; Drangova, M.; Holdsworth, D.W.; Johnson, G.A.

    2009-01-01

    Small animal imaging has a critical role in phenotyping, drug discovery, and in providing a basic understanding of mechanisms of disease. Translating imaging methods from humans to small animals is not an easy task. The purpose of this work is to review in vivo X-ray based small animal imaging, with a focus on in vivo micro-computed tomography (micro-CT) and digital subtraction angiography (DSA). We present the principles, technologies, image quality parameters and types of applications. We show that both methods can be used not only to provide morphological, but also functional information, such as cardiac function estimation or perfusion. Compared to other modalities, x-ray based imaging is usually regarded as being able to provide higher throughput at lower cost and adequate resolution. The limitations are usually associated with the relatively poor contrast mechanisms and potential radiation damage due to ionizing radiation, although the use of contrast agents and careful design of studies can address these limitations. We hope that the information will effectively address how x-ray based imaging can be exploited for successful in vivo preclinical imaging. PMID:18758005

  16. Blood flow measurement using digital subtraction angiography for assessing hemodialysis access function

    NASA Astrophysics Data System (ADS)

    Koirala, Nischal; Setser, Randolph M.; Bullen, Jennifer; McLennan, Gordon

    2017-03-01

    Blood flow rate is a critical parameter for diagnosing dialysis access function during fistulography where a flow rate of 600 ml/min in arteriovenous graft or 400-500 ml/min in arteriovenous fistula is considered the clinical threshold for fully functioning access. In this study, a flow rate computational model for calculating intra-access flow to evaluate dialysis access patency was developed and validated in an in vitro set up using digital subtraction angiography. Flow rates were computed by tracking the bolus through two regions of interest using cross correlation (XCOR) and mean arrival time (MAT) algorithms, and correlated versus an in-line transonic flow meter measurement. The mean difference (mean +/- standard deviation) between XCOR and in-line flow measurements for in vitro setup at 3, 6, 7.5 and 10 frames/s was 118+/-63 37+/-59 31+/-31 and 46+/-57 ml/min respectively while for MAT method it was 86+/-56 57+/-72 35+/-85 and 19+/-129 ml/min respectively. The result of this investigation will be helpful for selecting candidate algorithms while blood flow computational tool is developed for clinical application.

  17. A LabVIEW Platform for Preclinical Imaging Using Digital Subtraction Angiography and Micro-CT

    PubMed Central

    Badea, Cristian T.; Hedlund, Laurence W.; Johnson, G. Allan

    2013-01-01

    CT and digital subtraction angiography (DSA) are ubiquitous in the clinic. Their preclinical equivalents are valuable imaging methods for studying disease models and treatment. We have developed a dual source/detector X-ray imaging system that we have used for both micro-CT and DSA studies in rodents. The control of such a complex imaging system requires substantial software development for which we use the graphical language LabVIEW (National Instruments, Austin, TX, USA). This paper focuses on a LabVIEW platform that we have developed to enable anatomical and functional imaging with micro-CT and DSA. Our LabVIEW applications integrate and control all the elements of our system including a dual source/detector X-ray system, a mechanical ventilator, a physiological monitor, and a power microinjector for the vascular delivery of X-ray contrast agents. Various applications allow cardiac- and respiratory-gated acquisitions for both DSA and micro-CT studies. Our results illustrate the application of DSA for cardiopulmonary studies and vascular imaging of the liver and coronary arteries. We also show how DSA can be used for functional imaging of the kidney. Finally, the power of 4D micro-CT imaging using both prospective and retrospective gating is shown for cardiac imaging. PMID:27006920

  18. Effect of power Doppler and digital subtraction techniques on the comparison of myocardial contrast echocardiography with SPECT.

    PubMed

    Haluska, B; Case, C; Short, L; Anderson, J; Marwick, T H

    2001-05-01

    To compare the accuracy and feasibility of harmonic power Doppler and digitally subtracted colour coded grey scale imaging for the assessment of perfusion defect severity by single photon emission computed tomography (SPECT) in an unselected group of patients. Cohort study. Regional cardiothoracic unit. 49 patients (mean (SD) age 61 (11) years; 27 women, 22 men) with known or suspected coronary artery disease were studied with simultaneous myocardial contrast echo (MCE) and SPECT after standard dipyridamole stress. Regional myocardial perfusion by SPECT, performed with (99m)Tc tetrafosmin, scored qualitatively and also quantitated as per cent maximum activity. Normal perfusion was identified by SPECT in 225 of 270 segments (83%). Contrast echo images were interpretable in 92% of patients. The proportion of normal MCE by grey scale, subtracted, and power Doppler techniques were respectively 76%, 74%, and 88% (p < 0.05) at > 80% of maximum counts, compared with 65%, 69%, and 61% at < 60% of maximum counts. For each technique, specificity was lowest in the lateral wall, although power Doppler was the least affected. Grey scale and subtraction techniques were least accurate in the septal wall, but power Doppler showed particular problems in the apex. On a per patient analysis, the sensitivity was 67%, 75%, and 83% for detection of coronary artery disease using grey scale, colour coded, and power Doppler, respectively, with a significant difference between power Doppler and grey scale only (p < 0.05). Specificity was also the highest for power Doppler, at 55%, but not significantly different from subtracted colour coded images. Myocardial contrast echo using harmonic power Doppler has greater accuracy than with grey scale imaging and digital subtraction. However, power Doppler appears to be less sensitive for mild perfusion defects.

  19. Comparison of Accuracy of Conventional Periapical Radiography and Direct Digital Subtractions Radiography with or without Image Enhancement in the Diagnosis of Density Changes.

    PubMed

    Razi, Tahmineh; Mohammadi, Arezu; Ghojazadeh, Morteza

    2012-01-01

    In periapical radiographic technique, the changes will be visible only after considerable deposi-tion or resorption while digital subtraction technique visualizes slight density changes. This study was aimed to compare visualization of density changes in conventional periapical radiographs and digital subtraction technique with or without image enhancement. Three dry human mandibles with unspecified age and gender were selected. Conventional periapical and direct digital radiographs were taken from the anterior, and right and left posterior regions by step-wise placement of aluminum plates until the image of the plate was clearly visible. The radiographs taken with the direct digital technique were subtracted from the first radiograph using Photoshop software. Three observers evaluated the radiographs and the digital subtraction images with or without image enhancement. The density was recorded in each radiograph in which the image of the aluminum plate was completely visible. In all mandibles, the differences in diagnosis of densitychanges between the conventional periapical radiographic technique and the direct digital subtraction radiographic technique with or without image enhancement were statistically significant irrespective of the region under study (p<0.001). There were no significant differences in the diagnosis of density changes in all the three mandibles in the left and right posterior regions between the two radiographic techniques. However, the differences in the anterior region were statistically significant (p<0.001). Direct digital subtraction radiographic technique with or without image enhancement is a more efficacious technique in exhibiting minor density changes compared to conventional periapical radiographic technique.

  20. Accurate, fully-automated registration of coronary arteries for volumetric CT digital subtraction angiography

    NASA Astrophysics Data System (ADS)

    Razeto, Marco; Mohr, Brian; Arakita, Kazumasa; Schuijf, Joanne D.; Fuchs, Andreas; Kühl, J. Tobias; Chen, Marcus Y.; Kofoed, Klaus F.

    2014-03-01

    Diagnosis of coronary artery disease with Coronary Computed Tomography Angiography (CCTA) is complicated by the presence of signi cant calci cation or stents. Volumetric CT Digital Subtraction Angiography (CTDSA) has recently been shown to be e ective at overcoming these limitations. Precise registration of structures is essential as any misalignment can produce artifacts potentially inhibiting clinical interpretation of the data. The fully-automated registration method described in this paper addresses the problem by combining a dense deformation eld with rigid-body transformations where calci cations/stents are present. The method contains non-rigid and rigid components. Non-rigid registration recovers the majority of motion artifacts and produces a dense deformation eld valid over the entire scan domain. Discrete domains are identi ed in which rigid registrations very accurately align each calci cation/stent. These rigid-body transformations are combined within the immediate area of the deformation eld using a distance transform to minimize distortion of the surrounding tissue. A recent interim analysis of a clinical feasibility study evaluated reader con dence and diagnostic accuracy in conventional CCTA and CTDSA registered using this method. Conventional invasive coronary angiography was used as the reference. The study included 27 patients scanned with a second-generation 320-row CT detector in which 41 lesions were identi ed. Compared to conventional CCTA, CTDSA improved reader con dence in 13/36 (36%) of segments with severe calci cation and 3/5 (60%) of segments with coronary stents. Also, the false positive rate of CTDSA was reduced compared to conventional CCTA from 18% (24/130) to 14% (19/130).

  1. Quantitative blood flow measurements in the small animal cardiopulmonary system using digital subtraction angiography

    SciTech Connect

    Lin Mingde; Marshall, Craig T.; Qi, Yi; Johnston, Samuel M.; Badea, Cristian T.; Piantadosi, Claude A.; Johnson, G. Allan

    2009-11-15

    Purpose: The use of preclinical rodent models of disease continues to grow because these models help elucidate pathogenic mechanisms and provide robust test beds for drug development. Among the major anatomic and physiologic indicators of disease progression and genetic or drug modification of responses are measurements of blood vessel caliber and flow. Moreover, cardiopulmonary blood flow is a critical indicator of gas exchange. Current methods of measuring cardiopulmonary blood flow suffer from some or all of the following limitations--they produce relative values, are limited to global measurements, do not provide vasculature visualization, are not able to measure acute changes, are invasive, or require euthanasia. Methods: In this study, high-spatial and high-temporal resolution x-ray digital subtraction angiography (DSA) was used to obtain vasculature visualization, quantitative blood flow in absolute metrics (ml/min instead of arbitrary units or velocity), and relative blood volume dynamics from discrete regions of interest on a pixel-by-pixel basis (100x100 {mu}m{sup 2}). Results: A series of calibrations linked the DSA flow measurements to standard physiological measurement using thermodilution and Fick's method for cardiac output (CO), which in eight anesthetized Fischer-344 rats was found to be 37.0{+-}5.1 ml/min. Phantom experiments were conducted to calibrate the radiographic density to vessel thickness, allowing a link of DSA cardiac output measurements to cardiopulmonary blood flow measurements in discrete regions of interest. The scaling factor linking relative DSA cardiac output measurements to the Fick's absolute measurements was found to be 18.90xCO{sub DSA}=CO{sub Fick}. Conclusions: This calibrated DSA approach allows repeated simultaneous visualization of vasculature and measurement of blood flow dynamics on a regional level in the living rat.

  2. A 2D driven 3D vessel segmentation algorithm for 3D digital subtraction angiography data

    NASA Astrophysics Data System (ADS)

    Spiegel, M.; Redel, T.; Struffert, T.; Hornegger, J.; Doerfler, A.

    2011-10-01

    Cerebrovascular disease is among the leading causes of death in western industrial nations. 3D rotational angiography delivers indispensable information on vessel morphology and pathology. Physicians make use of this to analyze vessel geometry in detail, i.e. vessel diameters, location and size of aneurysms, to come up with a clinical decision. 3D segmentation is a crucial step in this pipeline. Although a lot of different methods are available nowadays, all of them lack a method to validate the results for the individual patient. Therefore, we propose a novel 2D digital subtraction angiography (DSA)-driven 3D vessel segmentation and validation framework. 2D DSA projections are clinically considered as gold standard when it comes to measurements of vessel diameter or the neck size of aneurysms. An ellipsoid vessel model is applied to deliver the initial 3D segmentation. To assess the accuracy of the 3D vessel segmentation, its forward projections are iteratively overlaid with the corresponding 2D DSA projections. Local vessel discrepancies are modeled by a global 2D/3D optimization function to adjust the 3D vessel segmentation toward the 2D vessel contours. Our framework has been evaluated on phantom data as well as on ten patient datasets. Three 2D DSA projections from varying viewing angles have been used for each dataset. The novel 2D driven 3D vessel segmentation approach shows superior results against state-of-the-art segmentations like region growing, i.e. an improvement of 7.2% points in precision and 5.8% points for the Dice coefficient. This method opens up future clinical applications requiring the greatest vessel accuracy, e.g. computational fluid dynamic modeling.

  3. Objective criteria for acceptability and constancy tests of digital subtraction angiography.

    PubMed

    de las Heras, Hugo; Torres, Ricardo; Fernández-Soto, José Miguel; Vañó, Eliseo

    2016-01-01

    Demonstrate an objective procedure to quantify image quality in digital subtraction angiography (DSA) and suggest thresholds for acceptability and constancy tests. Series of images were obtained in a DSA system simulating a small (paediatric) and a large patient using the dynamic phantom described in the IEC and DIN standards for acceptance tests of DSA equipment. Image quality was quantified using measurements of contrast-to-noise ratio (CNR). Overall scores combining the CNR of 10-100 mg/ml Iodine at a vascular diameter of 1-4 mm in a homogeneous background were defined. Phantom entrance surface air kerma (Ka,e) was measured with an ionisation chamber. The visibility of a low-contrast vessel in DSA images has been identified with a CNR value of 0.50 ± 0.03. Despite using 14 times more Ka,e (8.85 vs 0.63 mGy/image), the protocol for large patients showed a decrease in the overall score CNRsum of 67% (4.21 ± 0.06 vs 2.10 ± 0.05). The uncertainty in the results of the objective method was below 5%. Objective evaluation of DSA images using CNR is feasible with dedicated phantom measurements. An objective methodology has been suggested for acceptance tests compliant with the IEC/DIN standards. The defined overall scores can serve to fix a reproducible baseline for constancy tests, as well as to study the device stability within one acquisition series and compare different imaging protocols. This work provides aspects that have not been included in the recent European guidelines on Criteria for Acceptability of Medical Radiological Equipment. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  4. Classification-based summation of cerebral digital subtraction angiography series for image post-processing algorithms

    NASA Astrophysics Data System (ADS)

    Schuldhaus, D.; Spiegel, M.; Redel, T.; Polyanskaya, M.; Struffert, T.; Hornegger, J.; Doerfler, A.

    2011-03-01

    X-ray-based 2D digital subtraction angiography (DSA) plays a major role in the diagnosis, treatment planning and assessment of cerebrovascular disease, i.e. aneurysms, arteriovenous malformations and intracranial stenosis. DSA information is increasingly used for secondary image post-processing such as vessel segmentation, registration and comparison to hemodynamic calculation using computational fluid dynamics. Depending on the amount of injected contrast agent and the duration of injection, these DSA series may not exhibit one single DSA image showing the entire vessel tree. The interesting information for these algorithms, however, is usually depicted within a few images. If these images would be combined into one image the complexity of segmentation or registration methods using DSA series would drastically decrease. In this paper, we propose a novel method automatically splitting a DSA series into three parts, i.e. mask, arterial and parenchymal phase, to provide one final image showing all important vessels with less noise and moving artifacts. This final image covers all arterial phase images, either by image summation or by taking the minimum intensities. The phase classification is done by a two-step approach. The mask/arterial phase border is determined by a Perceptron-based method trained from a set of DSA series. The arterial/parenchymal phase border is specified by a threshold-based method. The evaluation of the proposed method is two-sided: (1) comparison between automatic and medical expert-based phase selection and (2) the quality of the final image is measured by gradient magnitudes inside the vessels and signal-to-noise (SNR) outside. Experimental results show a match between expert and automatic phase separation of 93%/50% and an average SNR increase of up to 182% compared to summing up the entire series.

  5. In vivo imaging of rat coronary arteries using bi-plane digital subtraction angiography

    PubMed Central

    Badea, Cristian T.; Hedlund, Laurence W.; Qi, Yi; Berridge, Brian; Johnson, G. Allan

    2011-01-01

    INTRODUCTION X-ray based digital subtraction angiography (DSA) is a common clinical imaging method for vascular morphology and function. Coronary artery characterization is one of its most important applications. We show that bi-plane DSA of rat coronary arteries can provide a powerful imaging tool for translational safety assessment in drug discovery. METHODS A novel, dual tube/detector system, constructed explicitly for preclinical imaging, supports image acquisition at 10 frames/second with 88-micron spatial resolution. Ventilation, x-ray exposure, and contrast injection are all precisely synchronized using a biological sequence controller implemented as a LabVIEW application. A set of experiments were performed to test and optimize the sampling and image quality. We applied the DSA imaging protocol to record changes in the visualization of coronaries and myocardial perfusion induced by a vasodilator drug, nitroprusside. The drug was infused into a tail vein catheter using a peristaltic infusion pump at a rate of 0.07 ml/h for 3 mins (dose: 0.0875 mg). Multiple DSA sequences were acquired before, during, and up to 25 minutes after drug infusion. Perfusion maps of the heart were generated in MATLAB to compare the drug effects over time. RESULTS The best trade-off between the injection time, pressure, and image quality was achieved at 60 PSI, with the injection of 150 ms occurring early in diastole (60 ms delay) and resulting in the delivery of 113 microL of contrast agent. DSA images clearly show the main branches of the coronary arteries in an intact, beating heart. The drug test demonstrated that DSA can detect relative changes in coronary circulation via perfusion maps. DISSCUSION The methodology for DSA imaging of rat coronary arteries can serve as a template for future translational studies to assist in safety evaluation of new pharmaceuticals. Although x-ray imaging involves radiation, the associated dose (0.4 Gy) is not a major limitation. PMID:21683146

  6. Classification-based summation of cerebral digital subtraction angiography series for image post-processing algorithms.

    PubMed

    Schuldhaus, D; Spiegel, M; Redel, T; Polyanskaya, M; Struffert, T; Hornegger, J; Doerfler, A

    2011-03-21

    X-ray-based 2D digital subtraction angiography (DSA) plays a major role in the diagnosis, treatment planning and assessment of cerebrovascular disease, i.e. aneurysms, arteriovenous malformations and intracranial stenosis. DSA information is increasingly used for secondary image post-processing such as vessel segmentation, registration and comparison to hemodynamic calculation using computational fluid dynamics. Depending on the amount of injected contrast agent and the duration of injection, these DSA series may not exhibit one single DSA image showing the entire vessel tree. The interesting information for these algorithms, however, is usually depicted within a few images. If these images would be combined into one image the complexity of segmentation or registration methods using DSA series would drastically decrease. In this paper, we propose a novel method automatically splitting a DSA series into three parts, i.e. mask, arterial and parenchymal phase, to provide one final image showing all important vessels with less noise and moving artifacts. This final image covers all arterial phase images, either by image summation or by taking the minimum intensities. The phase classification is done by a two-step approach. The mask/arterial phase border is determined by a Perceptron-based method trained from a set of DSA series. The arterial/parenchymal phase border is specified by a threshold-based method. The evaluation of the proposed method is two-sided: (1) comparison between automatic and medical expert-based phase selection and (2) the quality of the final image is measured by gradient magnitudes inside the vessels and signal-to-noise (SNR) outside. Experimental results show a match between expert and automatic phase separation of 93%/50% and an average SNR increase of up to 182% compared to summing up the entire series.

  7. Comparison of chest dual-energy subtraction digital tomosynthesis and dual-energy subtraction radiography for detection of pulmonary nodules: initial evaluations in human clinical cases.

    PubMed

    Gomi, Tsutomu; Nozaki, Miwako; Takeda, Tohoru; Umeda, Tokuo; Takahashi, Kazutoshi; Nakajima, Masahiro

    2013-11-01

    To compare initial evaluations of chest dual-energy subtraction digital tomosynthesis (DES-DT) and dual-energy subtraction radiography (DES-R) for detection of pulmonary nodules. DES-DT and DES-R systems with pulsed x-rays and rapid kV switching were used to evaluate pulmonary nodules (>4-6 mm, 2 nodules; >6-8 mm, 2 nodules; >8 mm, 32 nodules). Multidetector computed tomography was used as a reference. A filtered back-projection algorithm was used to reconstruct low-voltage (60 kVp), high-voltage (120 kVp), and soft-tissue or bone-subtracted tomograms of the desired layer thicknesses from the image data acquired during a single tomographic scan. DES-R images were processed from the low- and high-voltage images. To detect the pulmonary nodules, we used both systems to examine 36 patients with and 36 patients without pulmonary nodules. Two radiologists and three doctors of pulmonary medicine (average experience, 18 years) performed receiver operating characteristic (ROC) curve analysis to evaluate the results. The ROC analysis results suggested that the detection ability was significantly better for DES-DT than for DES-R (P < .0001; 95% confidence interval: DES-DT, 0.94 [0.83-0.99]; DES-R, 0.76 [0.68-0.85]; sensitivity: DES-DT, 87.7 ± 2.9%; DES-R, 53.8 ± 3.5%; specificity: DES-DT, 78.3 ± 5.6%; DES-R, 78.4 ± 3.4%; accuracy: DES-DT, 83.1 ± 3.8%, DES-R, 66.1 ± 2.0%). When the nodules were no longer superimposed over the normal structures, their characteristics and distribution could be observed much more clearly. Compared with DES-R, DES-DT provided greater sensitivity for detection of pulmonary nodules, particularly for the larger ones. Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.

  8. Estimating breast thickness for dual-energy subtraction in contrast-enhanced digital mammography using calibration phantoms

    NASA Astrophysics Data System (ADS)

    Lau, Kristen C.; Kwon, Young Joon; Aziz, Moez Karim; Acciavatti, Raymond J.; Maidment, Andrew D. A.

    2016-04-01

    Dual-energy contrast-enhanced digital mammography (DE CE-DM) uses an iodinated contrast agent to image the perfusion and vasculature of the breast. DE images are obtained by a weighted logarithmic subtraction of the high-energy (HE) and low-energy (LE) image pairs. We hypothesized that the optimal DE subtraction weighting factor is thickness-dependent, and developed a method for determining breast tissue composition and thickness in DE CE-DM. Phantoms were constructed using uniform blocks of 100% glandular-equivalent and 100% adipose-equivalent material. The thickness of the phantoms ranged from 3 to 8 cm, in 1 cm increments. For a given thickness, the glandular-adipose composition of the phantom was varied using different combinations of blocks. The logarithmic LE and logarithmic HE signal intensities were measured; they decrease linearly with increasing glandularity for a given thickness. The signals decrease with increasing phantom thickness and the x-ray signal decreases linearly with thickness for a given glandularity. As the thickness increases, the attenuation difference per additional glandular block decreases, indicating beam hardening. From the calibration mapping, we have demonstrated that we can predict percent glandular tissue and thickness when given two distinct signal intensities. Our results facilitate the subtraction of tissue at the boundaries of the breast, and aid in discriminating between contrast agent uptake in glandular tissue and subtraction artifacts.

  9. Supine Digital Subtraction Myelography for the Demonstration of a Dorsal Cerebrospinal Fluid Leak in a Patient with Spontaneous Intracranial Hypotension: A Technical Note

    PubMed Central

    Carstensen, Michael; Chaudhary, Navjot; Leung, Andrew; Ng, Wai

    2012-01-01

    A patient with spontaneous intracranial hypotension due to a spinal cerebrospinal fluid (CSF) leak required localization of the leakage site prior to surgical management. Conventional, computed tomography and prone digital subtraction myelography failed to localize the dural tear, which was postulated to be dorsally located. We present here a digital subtraction myelographic approach to accurately localize a dorsal site of CSF leakage by injecting iodinated contrast via a lumbar drain with the patient in the supine position. PMID:23378882

  10. Digital subtraction radiographic analysis of the combination of bioabsorbable membrane and bovine morphogenetic protein pool in human periodontal infrabony defects

    PubMed Central

    GUIMARÃES, Maria do Carmo Machado; PASSANEZI, Euloir; SANT’ANA, Adriana Campos Passanezi; GREGHI, Sebastião Luiz Aguiar; TABA JUNIOR, Mario

    2010-01-01

    Objectives This study assessed the bone density gain and its relationship with the periodontal clinical parameters in a case series of a regenerative therapy procedure. Material and Methods Using a split-mouth study design, 10 pairs of infrabony defects from 15 patients were treated with a pool of bovine bone morphogenetic proteins associated with collagen membrane (test sites) or collagen membrane only (control sites). The periodontal healing was clinically and radiographically monitored for six months. Standardized presurgical and 6-month postoperative radiographs were digitized for digital subtraction analysis, which showed relative bone density gain in both groups of 0.034 ± 0.423 and 0.105 ± 0.423 in the test and control group, respectively (p>0.05). Results As regards the area size of bone density change, the influence of the therapy was detected in 2.5 mm2 in the test group and 2 mm2 in the control group (p>0.05). Additionally, no correlation was observed between the favorable clinical results and the bone density gain measured by digital subtraction radiography (p>0.05). Conclusions The findings of this study suggest that the clinical benefit of the regenerative therapy observed did not come with significant bone density gains. Long-term evaluation may lead to a different conclusions. PMID:20835573

  11. Multimodality evaluation of dural arteriovenous fistula with CT angiography, MR with arterial spin labeling, and digital subtraction angiography: case report.

    PubMed

    Alexander, Matthew; McTaggart, Ryan; Santarelli, Justin; Fischbein, Nancy; Marks, Michael; Zaharchuk, Greg; Do, Huy

    2014-01-01

    Dural arteriovenous fistulae (DAVF) are cerebrovascular lesions with pathologic shunting into the venous system from arterial feeders. Digital subtraction angiography (DSA) has long been considered the gold standard for diagnosis, but advances in noninvasive imaging techniques now play a role in the diagnosis of these complex lesions. Herein, we describe the case of a patient with right-side pulsatile tinnitus and DAVF diagnosed using computed tomography angiography, magnetic resonance with arterial spin labeling, and DSA. Implications for imaging analysis of DAVFs and further research are discussed.

  12. ANGY: A Rule-Based Expert System for Automatic Segmentation of Coronary Vessels From Digital Subtracted Angiograms.

    PubMed

    Stansfield, S A

    1986-02-01

    This paper details the design and implementation of ANGY, a rule-based expert system in the domain of medical image processing. Given a subtracted digital angiogram of the chest, ANGY identifies and isolates the coronary vessels, while ignoring any nonvessel structures which may have arisen from noise, variations in background contrast, imperfect subtraction, and irrelevent anatomical detail. The overall system is modularized into three stages: the preprocessing stage and the two stages embodied in the expert itself. In the preprocessing stage, low-level image processing routines written in C are used to create a segmented representation of the input image. These routines are applied sequentially. The expert system is rule-based and is written in OPS5 and LISP. It is separated into two stages: The low-level image processing stage embodies a domain-independent knowledge of segmentation, grouping, and shape analysis. Working with both edges and regions, it determines such relations as parallel and adjacent and attempts to refine the segmentation begun by the preprocessing. The high-level medical stage embodies a domain-dependent knowledge of cardiac anatomy and physiology. Applying this knowledge to the objects and relations determined in the preceding two stages, it identifies those objects which are vessels and eliminates all others.

  13. Matching of projection imaging and tomographic imaging: application to digital subtracted angiography (DSA) and magnetic resonance angiography (MRA)

    NASA Astrophysics Data System (ADS)

    Vermandel, Maximilien; Kulik, Carine; Leclerc, Xavier; Rousseau, Jean; Vasseur, Christian

    2002-05-01

    This study proposes a new method for matching vascular imaging modalities without the use of external frame or external landmarks. We first perform a 3D reconstruction of a piece of the cerebral vascular tree using Magnetic Resonance Angiography (MRA). Then, this structure is projected on the Digital Subtracted Angiography (DSA) images until its best position and orientation are found. As the 3D structure is known in the MRA referential, this method enables us to match information from DSA and MRA. The complete matching of all the DSA images in many incidences and the MRA set have been obtained. For the DSA images, the epipolar constraint has been verified between all the incidences. This new approach in medical imaging brings a very original method, making easier and more efficient visualization and quantification of vascular information.

  14. Comparison of Efficacy of Intraoperative Indocyanine Green Videoangiography in Clipping of Anterior Circulation Aneurysms with Postoperative Digital Subtraction Angiography.

    PubMed

    Kumar, Vikas; Jagetia, Anita; Singh, Daljit; Srivastava, Arvind Kumar; Tandon, Monica Sehgal

    2017-01-01

    The aim of this study is to assess the efficacy of intraoperative indocyanine green videoangiography (ICG-VA) using postoperative digital subtraction angiography (DSA) in clipped anterior circulation aneurysms. A prospective study was conducted for 1 year which included thirty patients of anterior circulation aneurysm treated by clipping of aneurysm. Intraoperative ICG-VA was performed on all the patients. Postoperative DSA was performed to assess the efficacy of ICG-VA. Intraoperative ICG-VA revealed the occlusion of aneurysm in all the thirty patients. Postoperative DSA revealed aneurysm neck remnant in two patients and demonstrated no branch occlusion. Intraoperative ICG-VA is useful in assessing the completeness of clipping of cerebral aneurysms and ensures patency of branch vessels, thus providing a better postoperative outcome. It replaces the need for invasive postoperative angiographic imaging in a selected group of patients and is also cost effective.

  15. Three-dimensional MR digital subtraction angiography using parallel imaging and keyhole data sampling in cerebrovascular diseases: initial experience.

    PubMed

    Tsuchiya, Kazuhiro; Aoki, Chinatsu; Fujikawa, Akira; Hachiya, Junichi

    2004-08-01

    We assessed the feasibility of MR digital subtraction angiography (DSA) using parallel imaging and keyhole data sampling in the diagnosis of cerebrovascular diseases (CVDs) in 11 patients. Their diseases included arterial trunk stenosis/occlusion ( n=4), aneurysm ( n=3), arteriovenous malformation ( n=2), venous angioma ( n=1), and sinus thrombosis ( n=1). The technique depicted not only anatomical features, comparably to MR angiography ( n=10/11), but also hemodynamics such as collateral flow at a temporal resolution of 1.68 s/frame. When compared with conventional angiograms ( n=7), details were missed in four patients (incomplete demonstration of aneurysmal neck in two and poor separation of AVM components in two). Although inferior to conventional angiography, this technique can provide both anatomical and hemodynamic information of CVDs.

  16. Dual-energy contrast-enhanced digital mammography (DE-CEDM): optimization on digital subtraction with practical x-ray low/high-energy spectra

    NASA Astrophysics Data System (ADS)

    Chen, Biao; Jing, Zhenxue; Smith, Andrew P.; Parikh, Samir; Parisky, Yuri

    2006-03-01

    Dual-energy contrast enhanced digital mammography (DE-CEDM), which is based upon the digital subtraction of low/high-energy image pairs acquired before/after the administration of contrast agents, may provide physicians physiologic and morphologic information of breast lesions and help characterize their probability of malignancy. This paper proposes to use only one pair of post-contrast low / high-energy images to obtain digitally subtracted dual-energy contrast-enhanced images with an optimal weighting factor deduced from simulated characteristics of the imaging chain. Based upon our previous CEDM framework, quantitative characteristics of the materials and imaging components in the x-ray imaging chain, including x-ray tube (tungsten) spectrum, filters, breast tissues / lesions, contrast agents (non-ionized iodine solution), and selenium detector, were systemically modeled. Using the base-material (polyethylene-PMMA) decomposition method based on entrance low / high-energy x-ray spectra and breast thickness, the optimal weighting factor was calculated to cancel the contrast between fatty and glandular tissues while enhancing the contrast of iodized lesions. By contrast, previous work determined the optimal weighting factor through either a calibration step or through acquisition of a pre-contrast low/high-energy image pair. Computer simulations were conducted to determine weighting factors, lesions' contrast signal values, and dose levels as functions of x-ray techniques and breast thicknesses. Phantom and clinical feasibility studies were performed on a modified Selenia full field digital mammography system to verify the proposed method and computer-simulated results. The resultant conclusions from the computer simulations and phantom/clinical feasibility studies will be used in the upcoming clinical study.

  17. INTRAVENOUS REGIONAL ANTIBIOTIC PERFUSION THERAPY AS AN ADJUNCTIVE TREATMENT FOR DIGITAL LESIONS IN SEABIRDS.

    PubMed

    Fiorello, Christine V

    2017-03-01

    Foot infections are a common problem among seabirds in wildlife rehabilitation. Pododermatitis and digital infections are often challenging to treat because of the presence of suboptimal substrates, abnormal weight-bearing due to injuries, and suboptimal nutritional or health status. Seabirds represent the majority of animals requiring rehabilitation after oil spills, and foot problems are a common reason for euthanasia among these birds. Antibiotic intravenous regional perfusion therapy is frequently used in humans and other species to treat infections of the distal extremities, but it has not been evaluated in seabirds. During the 2015 Refugio oil spill response, four birds with foot lesions (pododermatitis, osteomyelitis, or both) were treated with ampicillin/sulbactam administered intravenously to the affected limb(s) in addition to systemic antibiotics and anti-inflammatories. Three of the birds, all brown pelicans ( Pelecanus occidentalis ) recovered rapidly and were released. Two of these birds had acute pododermatitis and were treated once with intravenous regional perfusion. They were released approximately 3 wk after the perfusion therapy. The third pelican had osteomyelitis of a digit. It was treated twice with intravenous regional perfusion and was released about 1 mo after the initial perfusion therapy. The fourth bird, a Pacific loon ( Gavia pacifica ), was treated once with perfusion therapy but did not respond to treatment and was euthanatized. No serious adverse effects were observed. This technique should be explored further in avian species.

  18. Contrast-enhanced angiographic computed tomography for detection of aneurysm remnants after clipping: a comparison with digital subtraction angiography in 112 clipped aneurysms.

    PubMed

    Gölitz, Philipp; Struffert, Tobias; Ganslandt, Oliver; Lang, Stefan; Knossalla, Frauke; Doerfler, Arnd

    2014-06-01

    For preclusion of remnants after aneurysm clipping, a reliable, noninvasive imaging technique is desirable. To evaluate the reliability of optimized angiographic computed tomography with intravenous contrast agent injection (ivACT) in detecting remnants after aneurysmal clipping compared with digital subtraction angiography (DSA), the gold standard. We included 84 patients with 112 clipped cerebral aneurysms of the anterior circulation. For treatment, 116 clips of cobalt and 57 clips of titanium alloy were used. In each patient, we performed an ivACT with dual rotational acquisition and a DSA. Data from ivACT were postprocessed with a dual-volume technique with newly implemented reconstructions modes. Aneurysm remnants were measured, classified, and correlated with DSA by 2 raters. In total, 12 remnants were revealed by DSA, meaning a prevalence of 11%. IvACT demonstrated a sensitivity of 75% to 92% and a specificity of 99% in detecting remnants up to a minimal size of 0.7 × 0.3 mm. Classification of remnants by ivACT was identical to that by DSA, and assessment of size showed a significant correlation with DSA (P < .001). No significant differences between cobalt and titanium alloy were revealed concerning artifacts. Optimized ivACT with enhanced postprocessing demonstrated high sensitivity and specificity in detecting remnants after aneurysm clipping in the anterior circulation. Classification and assessment of remnant size and detection of relevant parent artery stenosis showed high accuracy of ivACT compared with DSA. Our results indicate that ivACT might become a noninvasive alternative to DSA for postsurgical control.

  19. A feasibility study of projection-based energy weighting based on a photon-counting detector in contrast-enhanced digital subtraction mammography: A simulation study

    NASA Astrophysics Data System (ADS)

    Choi, Sunghoon; Lee, Seungwan; Choi, Yu-Na; Kim, Hee-Joung

    2014-06-01

    Contrast media, such as iodine and gadolinium, are generally used in digital subtraction mammography to enhance the contrast between target and background materials. In digital subtraction mammography, where one image (with contrast medium) is subtracted from another (anatomical background) to facilitate visualization of the tumor structure, tumors can be more easily distinguished after the injection of a contrast medium. In order to have more an effective method to increase the contrast-to-noise ratio (CNR), we applied a projection-based energy-weighting method. The purpose of this study is to demonstrate the feasibility of using the projection-based energy-weighting method in digital subtraction mammography. Unlike some other previous studies, we applied the projection-based energy-weighting method to more practical mammography conditions by using the Monte Carlo method to simulate four different iodine solutions embedded in a breast phantom comprised of 50% adipose and 50% glandular tissues. We also considered an optimal tube voltage and anode/filter combination in digital iodine contrast media mammography in order to maximize the figure-of-merit (FOM). The simulated source energy was from 20 to 45 keV to prevent electronic noise and include the k-edge energy of iodine (33.2 keV). The results showed that the projection-based energy-weighting improved the CNR by factors of 1.05-1.86 compared to the conventionally integrated images. Consequently, the CNR of digital subtraction mammography images can be improved by using projection-based energy-weighting with photon-counting detectors.

  20. Suppression of high-density artifacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

    NASA Astrophysics Data System (ADS)

    Baissalov, Roustem; Sandison, George A.; Donnelly, Bryan J.; Saliken, John C.; Muldrew, Ken; Rewcastle, John C.

    2000-06-01

    Image guidance of cryotherapy is usually performed using ultrasound or x-ray CT. Despite the ability of CT to display the full 3D structure of the iceball, including frozen and unfrozen regions, the quality of the images is compromised by the presence of high density streak artifacts. To suppress these artifacts we applied Temporal Digital Subtraction (TDS). This TDS method has the added advantage of improving the gray scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high density artifacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced content of the artifacts. This TDS can be used in x-ray CT assisted cryotherapy to significantly suppress or eliminate high density x-ray CT streak artifacts by digitally processing x-ray CT images. Applying TDS in cryotherapy will facilitate estimation of the amount and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent.

  1. Intra-aneurysmal flow patterns: illustrative comparison among digital subtraction angiography, optical flow, and computational fluid dynamics.

    PubMed

    Brina, O; Ouared, R; Bonnefous, O; van Nijnatten, F; Bouillot, P; Bijlenga, P; Schaller, K; Lovblad, K-O; Grünhagen, T; Ruijters, D; Pereira, V Mendes

    2014-12-01

    Digital subtraction angiography is the gold standard vascular imaging and it is used for all endovascular treatment of intracranial anerysms. Optical flow imaging has been described as a potential method to evaluate cerebral hemodynamics through DSA. In this study, we aimed to compare the flow patterns measured during angiography, by using an optical flow method, with those measured by using computational fluid dynamics in intracranial aneurysms. A consecutive series of 21 patients harboring unruptured saccular intracranial aneurysms who underwent diagnostic angiography before treatment was considered. High-frame-rate digital subtraction angiography was performed to obtain an intra-aneurysmal velocity field by following the cardiac-modulated contrast wave through the vascular structures by using optical flow principles. Additionally, computational fluid dynamics modeling was performed for every case by using patient-specific inlet-boundary conditions measured with the optical flow method from both DSA and 3D rotational angiography datasets. Three independent observers compared qualitatively both the inflow direction and the apparent recirculation in regular DSA, optical flow images, and computational fluid dynamics flow patterns for each patient; κ statistics were estimated. We included 21 patients. In 14 of these 21, the flow patterns were conclusive and matching between the optical flow images and computational fluid dynamics within the same projection view (κ = .91). However, in only 8 of these 14 patients the optical flow images were conclusive and matching regular DSA images (observer κ = 0.87). In 7 of the 21 patients, the flow patterns in the optical flow images were inconclusive, possibly due to improper projection angles. The DSA-based optical flow technique was considered qualitatively consistent with computational fluid dynamics outcomes in evaluating intra-aneurysmal inflow direction and apparent recirculation. Moreover, the optical flow technique

  2. Subtractive Leadership

    ERIC Educational Resources Information Center

    Larwin, K. H.; Thomas, Eugene M.; Larwin, David A.

    2015-01-01

    This paper introduces a new term and concept to the leadership discourse: Subtractive Leadership. As an extension of the distributive leadership model, the notion of subtractive leadership refers to a leadership style that detracts from organizational culture and productivity. Subtractive leadership fails to embrace and balance the characteristics…

  3. Use of cone-beam tomography and digital subtraction radiography for diagnosis and evaluation of traumatized teeth treated with endodontic surgery and MTA. A case report.

    PubMed

    de Carvalho, Fabíola Bastos; Gonçalves, Paloma Souza; Lima, Regina Karla de Pontes; Guerreiro-Tanomaru, Juliane Maria; Rasquin, Luis Cardoso; Tanomaru-Filho, Mário

    2013-10-01

    The aim of this paper was to report the diagnosis and evaluation of periradicular bone repair by using computed tomography and digital subtraction radiography in an endodontic surgery case treated with mineral trioxide aggregate (MTA). The patient had local swelling and fistula 7 years after trauma in the upper jaw. Periapical lesion on tooth #12 and root resorption of tooth #11 were detected radiographically. Endodontic therapy and placement of intracanal medication were carried out. After 3 months, with no improvement in the clinical signs and symptoms, computed tomography was performed, showing extensive apical bone resorption on tooth #12 and dental resorption promoting communication of the root canal with the periodontium of tooth #11. The patient was referred to endodontic surgery. After surgery and postoperative periods of 15, 30, 60, 90, and 120 days, standardized radiographs were taken, digitized, and subjected to digital subtraction of the images using Adobe Photoshop CS software. Four years later, a cone-beam computed tomography was performed, showing bone repair and absence of root resorption at tooth #11. In this clinical case, digital subtraction radiography was effective for early detection of new bone formation and evolution of repair. © 2011 John Wiley & Sons A/S.

  4. Significant dose reduction for pediatric digital subtraction angiography without impairing image quality: preclinical study in a piglet model.

    PubMed

    Racadio, John; Strauss, Keith; Abruzzo, Todd; Patel, Manish; Kukreja, Kamlesh; Johnson, Neil; den Hartog, Mark; Hoornaert, Bart; Nachabe, Rami

    2014-10-01

    The purpose of this study was to validate the hypothesis that image quality of digital subtraction angiography (DSA) in pediatrics is not impaired when using a low-dose acquisition protocol. Three piglets corresponding to common pediatric population sizes were used. DSA was performed in the aorta and renal, hepatic, and superior mesenteric arteries using both the commonly used reference standard and novel radiographic imaging noise reduction technologies to ensure pairwise radiation dose and image quality comparison. The air kerma per frame at the interventional reference point for each DSA acquisition was collected as a radiation dose measure, and image quality was evaluated by five interventional radiologists in a randomized blinded fashion using a 5-point scale. The mean air kerma (± SD) at the interventional reference point with the novel x-ray imaging noise reduction technology was significantly lower (1.1 ± 0.8 mGy/frame) than with the reference technology (4.2 ± 3.0 mGy/frame, p = 0.005). However, image quality was statistically similar, with average scores of 3.2 ± 0.4 and 3.1 ± 0.5 for the novel and reference technologies, respectively (p = 0.934); interrater absolute agreement was 0.77. The DSA radiation dose for pediatrics can be reduced by a factor of four with a novel x-ray imaging noise reduction technology without deterioration of image quality.

  5. Nonlinear Geometric Warping of the Mask Image: A New Method for Reducing Misregistration Artifacts in Digital Subtraction Angiography

    SciTech Connect

    Hayashi, Nobushige; Sakai, Toyohiko; Kitagawa, Manabu; Inagaki, Rika; Sadato, Norihiro; Ishii, Yasushi; Nishimoto, Yasuhiro; Tanaka, Masato; Fukushima, Tetsuya; Komuro, Hiroyuki; Ogura, Hisakazu; Kobayashi, Hidenori; Kubota, Toshihiko

    1998-03-15

    Purpose: Misregistration artifact is the major cause of image degradation in digital subtraction angiography (DSA). The purpose of this study was to evaluate the efficacy of a newly developed nonlinear geometric warping method to reduce misregistration artifact in DSA. Methods: The processing of the images was carried out on a workstation with a fully automatic computerized program. After making differential images with a lapracian filter, 49 regions of interest (ROIs) were set in the image to be processed. Each ROI of the live image scanned the corresponding ROI of the mask image searching for the best position to match itself. Each pixel of the mask image was shifted individually following the data calculated from the shifts of the ROIs. Five radiologists compared the images produced by the conventional parallel shift technique and those processed with this new method in 16 series of cerebral DSA. Results: In 14 of 16 series (88%), more radiologists judged the images processed with the new method to be better in quality. Small arteries near the skull base and veins of low density were clearly visualized in the images processed by the new method. Conclusion: This newly proposed method could be a simple and practical way to automatically reduce misregistration artifacts in DSA.

  6. Digital subtraction angiography imaging characteristics of patients with extra-intracranial atherosclerosis and its relationship to stroke.

    PubMed

    Liu, Juan; Jia, Xiao-Jun; Wang, Yan-Jiang; Zhang, Meng; Zhang, Tao; Zhou, Hua-Dong

    2014-07-01

    To investigate the angiographic characteristics and clinical features in patients with suspected extra-intracranial atherosclerosis in a large cohort of Chinese population. On the basis of digital subtraction angiography characteristics, pathological morphology of extra-intracranial atherosclerosis was divided into tortuosity, kinking, coiling, and stenosis in 2,218 individuals aged 45-89 years. The degree of stenosis was further divided into low-grade (<30 %), intermediate-grade (30-69 %), and high-grade stenosis (≥70 %). Clinical manifestations were divided into transient ischemic attack, cerebral infarction and cerebral hemorrhage. The prevalence of tortuosity and stenosis were significantly higher in the extracranial arterial system than that of intracranial arterial system. The prevalence of tortuosity and kinking were significantly higher on the left side than the right side. The prevalence of mild and moderate stenosis in the internal carotid artery was significantly higher in the left side than the right side. The incidence of cerebral infarction was significantly higher in the internal carotid arterial (ICA) system than the vertebrobasilar arterial (VBA) system. Tortuosity is a common carotid abnormality in the Chinese population. The prevalence of ICA tortuosity is higher than that of VBA. The incidence of cerebral infarction in each atherosclerosis group was significantly higher in ICA than that of VBA. The prevalence of stroke is higher in the ICA system than the VBA system. Kinkings and coilings may not have a clinical significance if these lesions are not associated with atheromatous plaques or carotid stenosis.

  7. Cerebral circulation time is prolonged and not correlated with EDSS in multiple sclerosis patients: a study using digital subtracted angiography.

    PubMed

    Monti, Lucia; Donati, Donatella; Menci, Elisabetta; Cioni, Samuele; Bellini, Matteo; Grazzini, Irene; Leonini, Sara; Galluzzi, Paolo; Bracco, Sandra; Severi, Sauro; Burroni, Luca; Casasco, Alfredo; Morbidelli, Lucia; Santarnecchi, Emiliano; Piu, Pietro

    2015-01-01

    Literature has suggested that changes in brain flow circulation occur in patients with multiple sclerosis. In this study, digital subtraction angiography (DSA) was used to measure the absolute CCT value in MS patients and to correlate its value to age at disease onset and duration, and to expand disability status scale (EDSS). DSA assessment was performed on eighty MS patients and on a control group of forty-four age-matched patients. CCT in MS and control groups was calculated by analyzing the angiographic images. Lesion and brain volumes were calculated in a representative group of MS patients. Statistical correlations among CCT and disease duration, age at disease onset, lesion load, brain volumes and EDSS were considered. A significant difference between CCT in MS patients (mean = 4.9s; sd = 1.27 s) and control group (mean = 2.8s; sd = 0.51 s) was demonstrated. No significant statistical correlation was found between CCT and the other parameters in all MS patients. Significantly increased CCT value in MS patients suggests the presence of microvascular dysfunctions, which do not depend on clinical and MRI findings. Hemodynamic changes may not be exclusively the result of a late chronic inflammatory process.

  8. Visualization of intrarenal vessels by 3.0-T MR angiography in comparison with digital subtraction angiography using renal specimens.

    PubMed

    Schenk, Jens-Peter; Friebe, Björn; Ley, Sebastian; Baudendistel, Klaus; Schoebinger, Max; Hähnel, Stefan; Mehrabi, Arianeb; Tröger, Jochen; Hallscheidt, Peter

    2006-10-01

    MRI at 3.0 T enables high-spatial resolution for renal MR angiography. Evaluation of an arterial tree model in animal kidney specimens with comparison of digital subtraction angiography (DSA) and high-field MRI to find out the maximum spatial resolution of intrarenal vessels. It was considered that objective quantitation of angiogram quality could be achieved. A total of 27 pig kidney specimens were examined by MR angiography (flash 3D) using a 3.0-T scanner (TRIO; Siemens, Erlangen, Germany) with an eight-channel head coil and a voxel size of 0.9x0.9x1.1 mm in the early arterial phase after implantation of a 4F catheter in the renal artery. DSA (Integris, Philips, Best, The Netherlands) was performed immediately after the MRI. With the help of semiautomated segmentation, all vessels were marked for comparison of the vessel trees. The Wilcoxon rank test was used for statistical evaluation of vessel numbers and branching depths. Objective comparison between DSA and MR angiography was achieved. High-field MR angiography had the ability to depict vessels up to the seventh branching on average. Significant differences in vessel delineation and counts were found from the fifth level of intrarenal branching onwards with DSA showing an advantage. High-field MRI has great potential in the detection of intrarenal arteries and is comparable to DSA in visualization of the central intrarenal vessel tree.

  9. Comparison Between 3D TOF Magnetic Resonance Angiography and Intraarterial Digital Subtraction Angiography in Imaging the Circle of Willis

    PubMed Central

    Ghazali, Rozita Mohd; Shuaib., Ibrahim Lutfi

    2003-01-01

    This study was done compare the accuracy of non-contrast enhanced 3D time of flight magnetic resonance angiography (3D TOF MRA) with intraarterial digital subtraction angiography (IADSA) in depicting the arterial segments of the circle of Willis. 398 arterial segments were analysed from 38 patients who underwent both non-contrast enhanced 3D TOF MRA and IADSA examinations in Hospital Universiti Sains Malaysia from November 1998 to December 2000. Two observers performed blinded retrospective analysis of the IADSA images and Maximum Intensity Projection display of the 3D TOF MRA of the circle of Willis on separate sessions. Non-contrast enhanced 3D TOF MRA was sensitive and specific in depicting the A1, A2, M1, P1 and Anterior Communicating segments of the circle of Willis with a sensitivity ranging from 94.5% to 100% and specificity ranging from 90.5% to 100%. However it was poor in depicting the Posterior Communicating segments with a sensitivity of 21.4%. MIP display of the non-contrast enhanced 3D TOF MRA is sensitive in depicting the anatomy of the circle of Willis except for the PCOM segment. It is thus a reliable method for screening of this arterial circle. PMID:23365498

  10. Multislice CT Angiography in Renal Artery Stent Evaluation: Prospective Comparison with Intra-Arterial Digital Subtraction Angiography

    SciTech Connect

    Raza, Syed A.; Chughtai, Aamer R.; Wahba, Mona; Cowling, Mark G.; Taube, David; Wright, Andrew R.

    2004-01-15

    Purpose: To assess the role of multislice computed tomography angiography (MCTA) in the evaluation of renal artery stents, using intra-arterial digital subtraction angiography (DSA) as the gold standard. Methods: Twenty consecutive patients (15 men, 5 women) with 23 renal artery stents prospectively underwent both MCTA and DSA. Axial images, multiplanar reconstructions and maximum intensity projection images were used for diagnosis. The MCTA and DSA images were each interpreted without reference to the result of the other investigation. Results:The three cases of restenosis on DSA were detected correctly by MCTA; in 19 cases where MCTA showed a fully patent stent, the DSA was also negative. Sensitivity and negative predictive value (NPV) of MCTA were therefore 100%. In four cases, MCTA showed apparently minimal disease which was not shown on DSA. These cases are taken as false positive giving a specificity of 80% and a positive predictive value of 43%. Conclusion: The high sensitivity and NPV suggest MCTA may be useful as a noninvasive screen for renal artery stentrestenosis. MCTA detected mild disease in a few patients which was not confirmed on angiography.

  11. Cerebral Circulation Time is Prolonged and Not Correlated with EDSS in Multiple Sclerosis Patients: A Study Using Digital Subtracted Angiography

    PubMed Central

    Monti, Lucia; Donati, Donatella; Menci, Elisabetta; Cioni, Samuele; Bellini, Matteo; Grazzini, Irene; Leonini, Sara; Galluzzi, Paolo; Severi, Sauro; Burroni, Luca; Casasco, Alfredo; Morbidelli, Lucia; Santarnecchi, Emiliano; Piu, Pietro

    2015-01-01

    Literature has suggested that changes in brain flow circulation occur in patients with multiple sclerosis. In this study, digital subtraction angiography (DSA) was used to measure the absolute CCT value in MS patients and to correlate its value to age at disease onset and duration, and to expand disability status scale (EDSS). DSA assessment was performed on eighty MS patients and on a control group of forty-four age-matched patients. CCT in MS and control groups was calculated by analyzing the angiographic images. Lesion and brain volumes were calculated in a representative group of MS patients. Statistical correlations among CCT and disease duration, age at disease onset, lesion load, brain volumes and EDSS were considered. A significant difference between CCT in MS patients (mean = 4.9s; sd = 1.27s) and control group (mean = 2.8s; sd = 0.51s) was demonstrated. No significant statistical correlation was found between CCT and the other parameters in all MS patients. Significantly increased CCT value in MS patients suggests the presence of microvascular dysfunctions, which do not depend on clinical and MRI findings. Hemodynamic changes may not be exclusively the result of a late chronic inflammatory process. PMID:25679526

  12. Development and evaluation of a digital subtraction angiography system using a large-area flat panel detector

    NASA Astrophysics Data System (ADS)

    Ikeda, Shigeyuki; Suzuki, Katsumi; Ishikawa, Ken; Colbeth, Richard E.; Webb, Chris; Tanaka, Saori; Okusako, Kenji

    2003-06-01

    We developed prototype Digital Subtraction Angiography (DSA) System with a new large area FPD. Dynamic range, MTF, Contrast ratio and line noise were much improved. The improved FPD is a scintillator-type detector, and has a 40 x 30 cm active area, 2048 x 1536 matrix with 194um pixel pitch. The Prototype DSA system has two x-ray detectors, the FPD and the I.I.-CCD camera, and we can choose them on demand. All images captured from both detectors at 3 frames/sec in DSA mode and 30 frames/sec in Fluoroscopy mode are forwarded to our image-processing unit. We applied the new DSA system to more than 150 studies and compared the results with images from the I.I.-CCD. In DSA mode, FPD System, which has a wide dynamic range, large detecting area, and good contrast ratio yielded superior angiogram images compared with the I.I-CCD system. In Fluoroscopy mode, we improved line noise and increased the contrast of catheters and guide wires with a new image processing technique. With these improvements, the image quality of the FPD System is superior to the I.I.-CCD system at the exposure range of over 2uR/frame (17.4 nGy/frame).

  13. A retrospective study of digital subtraction technique to detect sclerotic changes in alveolar bone on intraoral radiographs of bisphosphonate-treated patients

    PubMed Central

    Zaman, M U; Nakamoto, T; Tanimoto, K

    2013-01-01

    Objectives: Several reports have suggested that sclerotic changes in cancellous bone of the jaw and thickening of the lamina dura are characteristic radiographic changes of an early silent stage of bisphosphonate (BP)-related osteonecrosis of the jaw. No quantitative evaluation has been reported to support this hypothesis. Emago® software (Oral Diagnostic Systems, Amsterdam, Netherlands) can perform digital subtraction on intraoral radiographs even if they were obtained by non-standardized radiography, provided the dimensional error is within a certain limit. The purpose of this study was to evaluate whether sclerotic changes of alveolar bone or thickening of lamina dura in patients using BP can be detected using the subtraction function of Emago. Methods: The authors selected 46 pairs of intraoral radiographs of the mandibular molar area in dental patients. All radiographs were obtained at intervals of 6 months or more. Among the 46 pairs, 7 pairs were from patients who were being treated with BP (study subjects), and 39 pairs were from patients who had not been using BP (controls). All pairs of radiographs underwent digital subtraction by Emago. The number of pixels of the sclerotic areas was counted and compared between subjects and controls. Results: The sclerotic changes were significantly distinguishable in two of the seven subjects (28.6%) using BP. Conclusions: Digital subtraction function of Emago was able to detect sclerotic changes in alveolar bone. Therefore, it is suggested that the subtraction function of Emago is a useful tool for quantitatively detecting sclerotic changes that are observed at an early, silent stage of BP-related osteonecrosis of the jaw. PMID:24170801

  14. Initial testing of a 3D printed perfusion phantom using digital subtraction angiography

    PubMed Central

    Khobragade, Parag; Ying, Leslie; Snyder, Kenneth; Wack, David; Bednarek, Daniel R.; Rudin, Stephen; Ionita, Ciprian N.

    2015-01-01

    Perfusion imaging is the most applied modality for the assessment of acute stroke. Parameters such as Cerebral Blood Flow (CBF), Cerebral Blood volume (CBV) and Mean Transit Time (MTT) are used to distinguish the tissue infarct core and ischemic penumbra. Due to lack of standardization these parameters vary significantly between vendors and software even when provided with the same data set. There is a critical need to standardize the systems and make them more reliable. We have designed a uniform phantom to test and verify the perfusion systems. We implemented a flow loop with different flow rates (250, 300, 350 ml/min) and injected the same amount of contrast. The images of the phantom were acquired using a Digital Angiographic system. Since this phantom is uniform, projection images obtained using DSA is sufficient for initial validation. To validate the phantom we measured the contrast concentration at three regions of interest (arterial input, venous output, perfused area) and derived time density curves (TDC). We then calculated the maximum slope, area under the TDCs and flow. The maximum slope calculations were linearly increasing with increase in flow rate, the area under the curve decreases with increase in flow rate. There was 25% error between the calculated flow and measured flow. The derived TDCs were clinically relevant and the calculated flow, maximum slope and areas under the curve were sensitive to the measured flow. We have created a systematic way to calibrate existing perfusion systems and assess their reliability. PMID:26633914

  15. Initial testing of a 3D printed perfusion phantom using digital subtraction angiography

    NASA Astrophysics Data System (ADS)

    Wood, Rachel P.; Khobragade, Parag; Ying, Leslie; Snyder, Kenneth; Wack, David; Bednarek, Daniel R.; Rudin, Stephen; Ionita, Ciprian N.

    2015-03-01

    Perfusion imaging is the most applied modality for the assessment of acute stroke. Parameters such as Cerebral Blood Flow (CBF), Cerebral Blood volume (CBV) and Mean Transit Time (MTT) are used to distinguish the tissue infarct core and ischemic penumbra. Due to lack of standardization these parameters vary significantly between vendors and software even when provided with the same data set. There is a critical need to standardize the systems and make them more reliable. We have designed a uniform phantom to test and verify the perfusion systems. We implemented a flow loop with different flow rates (250, 300, 350 ml/min) and injected the same amount of contrast. The images of the phantom were acquired using a Digital Angiographic system. Since this phantom is uniform, projection images obtained using DSA is sufficient for initial validation. To validate the phantom we measured the contrast concentration at three regions of interest (arterial input, venous output, perfused area) and derived time density curves (TDC). We then calculated the maximum slope, area under the TDCs and flow. The maximum slope calculations were linearly increasing with increase in flow rate, the area under the curve decreases with increase in flow rate. There was 25% error between the calculated flow and measured flow. The derived TDCs were clinically relevant and the calculated flow, maximum slope and areas under the curve were sensitive to the measured flow. We have created a systematic way to calibrate existing perfusion systems and assess their reliability.

  16. Marginal Accuracy and Internal Fit of Dental Copings Fabricated by Modern Additive and Subtractive Digital Technologies.

    PubMed

    Nelson, Neha; K S, Jyothi; Sunny, Kiran

    2017-03-01

    The margins of copings for crowns and retainers of fixed partial dentures affect the progress of microleakage and dental caries. Failures occur due to altered fit which is also influenced by the method of fabrication. An in-vitro study was conducted to determine among the cast base metal, copy milled zirconia, computer aided designing computer aided machining/manufacturing zirconia and direct metal laser sintered copings which showed best marginal accuracy and internal fit. Forty extracted maxillary premolars were mounted on an acrylic model and reduced occlusally using a milling machine up to a final tooth height of 4 mm from the cementoenamel junction. Axial reduction was accomplished on a surveyor and a chamfer finish line was given. The impressions and dies were made for fabrication of copings which were luted on the prepared teeth under standardized loading, embedded in self-cure acrylic resin, sectioned and observed using scanning electron microscope for internal gap and marginal accuracy. The copings fabricated using direct metal laser sintering technique exhibited best marginal accuracy and internal fit. Comparison of mean between the four groups by ANOVA and post-hoc Tukey HSD tests showed a statistically significant difference between all the groups (p⟨0.05). It was concluded that the copings fabricated using direct metal laser sintering technique exhibited best marginal accuracy and internal fit. Additive digital technologies such as direct metal laser sintering could be cost-effective for the clinician, minimize failures related to fit and increase longevity of teeth and prostheses. Copyright© 2017 Dennis Barber Ltd.

  17. Pedal angiography in peripheral arterial occlusive disease: first-pass i.v. contrast-enhanced MR angiography with blood pool contrast medium versus intraarterial digital subtraction angiography.

    PubMed

    Kos, Sebastian; Reisinger, Clemens; Aschwanden, Markus; Bongartz, Georg M; Jacob, Augustinus L; Bilecen, Deniz

    2009-03-01

    The purpose of this study was to prospectively evaluate first-pass i.v. gadofosveset-enhanced MR angiography in patients with peripheral arterial occlusive disease for visualization of the pedal arteries and stenosis or occlusion of those arteries with intraarterial digital subtraction angiography as the reference standard. Twenty patients with peripheral arterial occlusive disease (nine women, 11 men; age-range 58-83 years) were prospectively enrolled. Gadofosveset first-pass contrast-enhanced MR angiography was performed with a 1.5-T system, a dedicated foot coil, and cuff compression to the calf. Arterial segments were assessed for degree of arterial stenosis, arterial visibility, diagnostic utility, and venous contamination. Detection of vessel stenosis or occlusion was evaluated in comparison with findings at digital subtraction angiography. The unpaired Student's t test was used to test arterial visibility with the two techniques. First-pass MR angiography with gadofosveset had good diagnostic utility in 83.9% of all segments and no venous contamination in 96.8% of all segments. There was no difference between the performance of intraarterial digital subtraction angiography and that of i.v. contrast-enhanced MR angiography in arterial visibility overall (p = 0.245) or in subgroup analysis of surgical arterial bypass targets (p = 0.202). The overall sensitivity, specificity, and accuracy of i.v. gadofosveset-enhanced MR angiography for characterization of clinically significant stenosis and occlusion were 91.4%, 96.1%, and 93.9%. In the subgroup analysis, the sensitivity, specificity, and accuracy were 85.5%, 96.5%, and 92.1%. Gadofosveset-enhanced MR angiography of the pedal arteries in patients with peripheral arterial occlusive disease has arterial visibility equal to that of digital subtraction angiography and facilitates depiction of clinically significant stenosis and occlusion.

  18. An automatic fuzzy-based multi-temporal brain digital subtraction angiography image fusion algorithm using curvelet transform and content selection strategy.

    PubMed

    Momeni, Saba; Pourghassem, Hossein

    2014-08-01

    Recently image fusion has prominent role in medical image processing and is useful to diagnose and treat many diseases. Digital subtraction angiography is one of the most applicable imaging to diagnose brain vascular diseases and radiosurgery of brain. This paper proposes an automatic fuzzy-based multi-temporal fusion algorithm for 2-D digital subtraction angiography images. In this algorithm, for blood vessel map extraction, the valuable frames of brain angiography video are automatically determined to form the digital subtraction angiography images based on a novel definition of vessel dispersion generated by injected contrast material. Our proposed fusion scheme contains different fusion methods for high and low frequency contents based on the coefficient characteristic of wrapping second generation of curvelet transform and a novel content selection strategy. Our proposed content selection strategy is defined based on sample correlation of the curvelet transform coefficients. In our proposed fuzzy-based fusion scheme, the selection of curvelet coefficients are optimized by applying weighted averaging and maximum selection rules for the high frequency coefficients. For low frequency coefficients, the maximum selection rule based on local energy criterion is applied to better visual perception. Our proposed fusion algorithm is evaluated on a perfect brain angiography image dataset consisting of one hundred 2-D internal carotid rotational angiography videos. The obtained results demonstrate the effectiveness and efficiency of our proposed fusion algorithm in comparison with common and basic fusion algorithms.

  19. Computed Tomographic Angiography as an Adjunct to Digital Subtraction Angiography for the Pre-Operative Assessment of Cerebral Aneurysms

    PubMed Central

    Farsad, Khashayar; Mamourian, Alexander C; Eskey, Clifford J; Friedman, Jonathan A

    2009-01-01

    Objectives: Computerized tomographic angiography (CTA) has emerged as a valuable diagnostic tool for the management of patients with cerebrovascular disease. The use of CTA in lieu of, or as an adjunct to, conventional cerebral angiography in the management of cerebral aneurysms awaits further experience. In this study, we evaluated the role of CTA specifically for the pre-operative assessment and planning of cerebral aneurysm surgery. Patients and Methods: We reviewed the relevant neuroimaging of all patients treated at Dartmouth Hitchcock Medical Center between January, 2001 and December, 2004 with a diagnosis of cerebral aneurysm and diagnostic evaluation with both CTA and conventional digital subtraction angiography (DSA) using standard imaging protocols. 32 patients underwent both CTA and DSA during the study period for a total of 36 aneurysms. Images were independently re-assesed by two neurosurgeons for information valuable for pre-operative surgical planning. Results: In 26 of 36 aneurysms (72%), the CTA was felt to provide the best image quality in defining the morphology of the aneurysm. In 14 aneurysms (39%), CTA provided clinically valuable anatomic detail not demonstrated on DSA, largely due to better visualization of parent and perforating vessel relationships at the aneurysm neck. There were no instances where a lesion was seen on DSA but missed on CTA. The DSA was of most clinical value in determining flow dynamics, such as the arterial supply of an anterior communicating artery aneurysm and distal anterior cerebral branches via the two A1 segments. Conclusion: CTA with three-dimensional reconstructions is a valuable adjunct to the preoperative evaluation of cerebral aneurysms. We advocate routine use of CTA in all patients in whom surgical aneurysm repair is planned, even when DSA has already been performed. PMID:19452029

  20. Color-Coded Digital Subtraction Angiography in the Management of a Rare Case of Middle Cerebral Artery Pure Arterial Malformation

    PubMed Central

    Feliciano, Caleb E; Pamias-Portalatin, Eva; Mendoza-Torres, Jorge; Effio, Euclides; Moran, Yadira; Rodriguez-Mercado, Rafael

    2014-01-01

    Summary The advent of flow dynamics and the recent availability of perfusion analysis software have provided new diagnostic tools and management possibilities for cerebrovascular patients. To this end, we provide an example of the use of color-coded angiography and its application in a rare case of a patient with a pure middle cerebral artery (MCA) malformation. A 42-year-old male chronic smoker was evaluated in the emergency room due to sudden onset of severe headache, nausea, vomiting and left-sided weakness. Head computed tomography revealed a right basal ganglia hemorrhage. Cerebral digital subtraction angiography (DSA) showed a right middle cerebral artery malformation consisting of convoluted and ectatic collateral vessels supplying the distal middle cerebral artery territory-M1 proximally occluded. An associated medial lenticulostriate artery aneurysm was found. Brain single-photon emission computed tomography with and without acetazolamide failed to show problems in vascular reserve that would indicate the need for flow augmentation. Twelve months after discharge, the patient recovered from the left-sided weakness and did not present any similar events. A follow-up DSA and perfusion study using color-coded perfusion analysis showed perforator aneurysm resolution and adequate, albeit delayed perfusion in the involved vascular territory. We propose a combined congenital and acquired mechanism involving M1 occlusion with secondary dysplastic changes in collateral supply to the distal MCA territory. Angiographic and cerebral perfusion work-up was used to exclude the need for flow augmentation. Nevertheless, the natural course of this lesion remains unclear and long-term follow-up is warranted. PMID:25496681

  1. CT angiographic analysis of carotid artery stenosis: comparison of manual assessment, semiautomatic vessel analysis, and digital subtraction angiography.

    PubMed

    Silvennoinen, H M; Ikonen, S; Soinne, L; Railo, M; Valanne, L

    2007-01-01

    To compare multisection CT angiography (CTA) analyzed with source/maximum intensity projection (MIP) images as well as semiautomated vessel analysis software with intra-arterial digital subtraction angiography (DSA) in detection and grading of carotid artery bifurcation stenosis. Consecutive patients with sonography evidence of a marked internal carotid artery stenosis underwent both carotid CTA and DSA (37 patients, 73 vessels). In CTA, the grade of stenosis was determined using axial source and MIP images as well as vessel analysis. The scans were blind-analyzed by 2 neuroradiologists using the NASCET criteria. Correlation of CTA source/MIP images versus DSA estimates of stenosis (R = 0.95) was higher than for the vessel analysis method versus DSA (R = 0.89). Compared with DSA, CTA source/MIP images underestimated high (78.2% versus 86.4%, P < .05) and moderate grades of stenosis (57.3% versus 63.1%, P < .05) to a lesser extent than the vessel analysis method (68.5% versus 83.5% and 51.8% versus 63.1%, P < .05). For a high-grade stenosis, sensitivity and specificity of source/MIP image CTA were 75% and 96%, respectively, whereas for the vessel analysis method, they were 47% and 96%, respectively. For moderate stenosis, the source/MIP image CTA sensitivity and specificity were 88% and 82%, respectively, and for vessel analysis method, 62% and 82%, respectively. CTA detected all 4 occlusions. In evaluation of carotid stenosis, CTA provides an adequate, less invasive alternative with a high correlation to conventional DSA, though it tends to underestimate clinically relevant grades of stenosis. Its accuracy is not improved by semiautomated analysis. The data support the use of CTA in confirming carotid occlusion.

  2. Comparison of contrast-enhanced multi-station MR angiography and digital subtraction angiography of the lower extremity arterial disease.

    PubMed

    Burbelko, Mykhaylo; Augsten, Michael; Kalinowski, Marc O; Heverhagen, Johannes T

    2013-06-01

    To compare diagnostic accuracy of multi-station, high-spatial resolution contrast-enhanced MR angiography (CE-MRA) of the lower extremities with digital subtraction angiography (DSA) as the reference standard in patients with symptomatic peripheral arterial occlusive disease. Of 485 consecutive patients undergoing a run-off CE-MRA, 152 patients (86 male, 66 female; mean age, 71.6 years) with suspected peripheral arterial occlusive disease were included into our Institutional Review Board approved study. All patients underwent MRA and DSA of the lower extremities within 30 days. MRA was performed at 1.5 Tesla with a single bolus of 0.1 mmol/kg body weight of gadobutrol administered at a rate of 2.0 mL/s at three stations. Two readers evaluated the MRA images independently for stenosis grade and image quality. Sensitivity and specificity were derived. Sensitivity and specificity ranged from 73% to 93% and 64% to 89% and were highest in the thigh area. Both readers showed comparable results. Evaluation of good and better quality MRAs resulted in a considerable improvement in diagnostic accuracy. Contrast-enhanced MRA demonstrates good sensitivity and specificity in the investigation of the vasculature of the lower extremities. While a minor investigator experience dependence remains, it is standardizable and shows good inter-observer agreement. Our results confirm that the administration of Gadobutrol at a standard dose of 0.1 mmol/kg for contrast-enhanced runoff MRA is able to detect hemodynamically relevant stenoses. Use of contrast-enhanced MRA as an alternative to intra-arterial DSA in the evaluation and therapeutic planning of patients with suspected peripheral arterial occlusive disease is well justified. Copyright © 2012 Wiley Periodicals, Inc.

  3. Detection of Intravascular Injection During Lumbar Medial Branch Blocks: A Comparison of Aspiration, Live Fluoroscopy, and Digital Subtraction Technology.

    PubMed

    Kennedy, David J; Mattie, Ryan; Scott Hamilton, Alan; Conrad, Bryan; Smuck, Matthew

    2016-06-01

    Medial branch blocks may have unrecognized vascular uptake potentially resulting in false- negative results. To determine the rate of unintended vascular injection of contrast medium during medial branch blocks (MBB) with digital subtraction (DS) technology in the context of negative vascular uptake as determined by live fluoroscopy. Prospective Study in an academic medical center. 344 consecutive MBBs in 80 subjects. The presence of vascular flow as determined by live fluoroscopy and DS technology. Unintended vascular injection of contrast medium was determined on 344 consecutive MBBs in 84 subjects, first using live fluoroscopy followed by DS. If live fluoroscopy initially detected vascular uptake, the needle was repositioned until no vascular flow was detected. Once no vascular uptake was confirmed by live fluoroscopy, a contrast medium was then injected while being visualized with DS to again assess the presence or absence of vascular flow undetected by live fluoroscopy. Live fluoroscopy revealed inadvertent vascular uptake in 38 of the 344 blocks [11% (95% CI 8.0-15%)]. DS uncovered an additional 27 of the 344 blocks [7.8% (95% CI 5.3-11.4%)] with evidence of vascular uptake that were not detected with conventional live fluoroscopy. DS enhances the ability to detect inadvertent vascular flow during medial branch blocks. This study demonstrates that standard live fluoroscopy can miss a small percentage of cases with unintentional vascular uptake during MBB when compared with DS and may contribute to occasional false-negative responses. © 2016 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Multislice computerized tomography angiography in the evaluation of intracranial aneurysms: a comparison with intraarterial digital subtraction angiography.

    PubMed

    Wintermark, Max; Uske, Antoine; Chalaron, Marc; Regli, Luca; Maeder, Philippe; Meuli, Reto; Schnyder, Pierre; Binaghi, Stefano

    2003-04-01

    The goal of this study was to assess the diagnostic accuracy of computerized tomography (CT) angiography performed with the aid of multislice technology (MSCT angiography) in the investigation of intracranial aneurysms, by comparing this method with intraarterial digital subtraction (IADS) angiography. Fifty consecutive adult patients, who successively underwent MSCT angiography (four rows) and IADS angiography of intracranial vessels, were prospectively identified. The MSCT angiography studies consisted of 1.25-mm slices, with 0.8-mm reconstruction intervals, a pitch of 0.75, and timing determined by a test bolus. Two neuroradiologists, who were blinded to the initial interpretation of the MSCT angiograms as well as to those of the IADS angiograms, independently reviewed the MSCT angiograms for the detection and characterization of intracranial aneurysms. Forty-nine intracranial aneurysms were identified in 40 patients; 33 of these lesions were responsible for subarachnoid hemorrhage. The sensitivity, specificity, and accuracy of MSCT angiography in the detection of intracranial aneurysms were 94.8, 95.2, and 94.9%, respectively, on a per-aneurysm basis and 99, 95.2, and 98.3%, respectively, on a per-patient basis. Interobserver agreement was 98%. There was an excellent correlation between aneurysm size assessed using MSCT angiography and that determined by IADS angiography (slope = 0.916, r = 0.877, p < 0.001); however, 2 mm stood as the cutoff size below which the sensitivity of MSCT angiography was statistically lower. That method displayed great accuracy in characterizing the morphological characteristics of the aneurysm. Multislice CT angiography is an accurate and robust noninvasive screening test for intracranial aneurysms. It performs better than that reported for single-slice CT angiography. Introduction of eight- and especially 16-row MSCT angiography will provide further progression through thinner slices, a lower pitch, and a purely arterial phase.

  5. Effect of injection technique on temporal parametric imaging derived from digital subtraction angiography in patient specific phantoms

    NASA Astrophysics Data System (ADS)

    Ionita, Ciprian N.; Garcia, Victor L.; Bednarek, Daniel R.; Snyder, Kenneth V.; Siddiqui, Adnan H.; Levy, Elad I.; Rudin, Stephen

    2014-03-01

    Parametric imaging maps (PIM's) derived from digital subtraction angiography (DSA) for the cerebral arterial flow assessment in clinical settings have been proposed, but experiments have yet to determine the reliability of such studies. For this study, we have observed the effects of different injection techniques on PIM's. A flow circuit set to physiologic conditions was created using an internal carotid artery phantom. PIM's were derived for two catheter positions, two different contrast bolus injection volumes (5ml and 10 ml), and four injection rates (5, 10, 15 and 20 ml/s). Using a gamma variate fitting approach, we derived PIM's for mean-transit-time (MTT), time-to-peak (TTP) and bolus-arrivaltime (BAT). For the same injection rates, a larger bolus resulted in an increased MTT and TTP, while a faster injection rate resulted in a shorter MTT, TTP, and BAT. In addition, the position of the catheter tip within the vasculature directly affected the PIM. The experiment showed that the PIM is strongly correlated with the injection conditions, and, therefore, they have to be interpreted with caution. PIM images must be taken from the same patient to be able to be meaningfully compared. These comparisons can include pre- and post-treatment images taken immediately before and after an interventional procedure or simultaneous arterial flow comparisons through the left and right cerebral hemispheres. Due to the strong correlation between PIM and injection conditions, this study indicates that this assessment method should be used only to compare flow changes before and after treatment within the same patient using the same injection conditions.

  6. Effect of injection technique on temporal parametric imaging derived from digital subtraction angiography in patient specific phantoms

    PubMed Central

    Ionita, Ciprian N; Garcia, Victor L.; Bednarek, Daniel R; Snyder, Kenneth V; Siddiqui, Adnan H; Levy, Elad I; Rudin, Stephen

    2014-01-01

    Parametric imaging maps (PIM’s) derived from digital subtraction angiography (DSA) for the cerebral arterial flow assessment in clinical settings have been proposed, but experiments have yet to determine the reliability of such studies. For this study, we have observed the effects of different injection techniques on PIM’s. A flow circuit set to physiologic conditions was created using an internal carotid artery phantom. PIM’s were derived for two catheter positions, two different contrast bolus injection volumes (5ml and 10 ml), and four injection rates (5, 10, 15 and 20 ml/s). Using a gamma variate fitting approach, we derived PIM’s for mean-transit-time (MTT), time-to-peak (TTP) and bolus-arrivaltime (BAT). For the same injection rates, a larger bolus resulted in an increased MTT and TTP, while a faster injection rate resulted in a shorter MTT, TTP, and BAT. In addition, the position of the catheter tip within the vasculature directly affected the PIM. The experiment showed that the PIM is strongly correlated with the injection conditions, and, therefore, they have to be interpreted with caution. PIM images must be taken from the same patient to be able to be meaningfully compared. These comparisons can include pre- and post-treatment images taken immediately before and after an interventional procedure or simultaneous arterial flow comparisons through the left and right cerebral hemispheres. Due to the strong correlation between PIM and injection conditions, this study indicates that this assessment method should be used only to compare flow changes before and after treatment within the same patient using the same injection conditions. PMID:25302010

  7. CT Angiography of Peripheral Arterial Disease by 256-Slice Scanner: Accuracy, Advantages and Disadvantages Compared to Digital Subtraction Angiography.

    PubMed

    Mishra, Atul; Jain, Narendra; Bhagwat, Anand

    2017-07-01

    Peripheral arterial occlusive disease (PAOD) may cause disabling claudication or critical limb ischemia. Multidetector computed tomography (CT) technology has evolved to the level of 256-slice CT scanners which has significantly improved the spatial and temporal resolution of the images. This has provided the capability of chasing the contrast bolus at a fast speed enabling angiographic imaging of long segments of the body. These images can be reconstructed in various planes and various modes for detailed analysis of the peripheral vascular diseases which helps in making treatment decision. The aim of this retrospective study was to compare the CT angiograms (CTAs) of all cases of PAOD done by 256-slice CT scanner at a tertiary care vascular center and comparing these images with the digital subtraction angiograms (DSAs) of these patients. The retrospective study included 53 patients who underwent both CTA and DSA at our center over a period of 3 years from March 2013 to March 2016. The CTA showed high sensitivity (93%) and specificity (92.7%) for overall assessment of degree of stenosis in a vascular segment in cases of aortic and lower limb occlusive disease. The assessment of lesions of infrapopliteal segment was comparatively inferior (sensitivity 91.6%, accuracy 73.3%, and positive predictive value 78.5%), more so in the presence of significant calcification. The advantages of CTA were its noninvasive nature, ability to image large area of body, almost no adverse effects to the patients, and better assessment of vessel wall disease. However, the CTA assessment of collaterals was inferior with a sensitivity of only 62.7% as compared to DSA. Overall, 256-slice CTA provides fast and accurate imaging of vascular tree which can restrict DSA only in few selected cases as a problem-solving tool where clinico-radiological mismatch is present.

  8. Noncontrast dynamic MRA in intracranial arteriovenous malformation (AVM), comparison with time of flight (TOF) and digital subtraction angiography (DSA).

    PubMed

    Yu, Songlin; Yan, Lirong; Yao, Yuqiang; Wang, Shuo; Yang, Mingqi; Wang, Bo; Zhuo, Yan; Ai, Lin; Miao, Xinyuan; Zhao, Jizong; Wang, Danny J J

    2012-07-01

    Digital subtraction angiography (DSA) remains the gold standard to diagnose intracranial arteriovenous malformations (AVMs) but is invasive. Existing magnetic resonance angiography (MRA) is suboptimal for assessing the hemodynamics of AVMs. The objective of this study was to evaluate the clinical utility of a novel noncontrast four-dimensional (4D) dynamic MRA (dMRA) in the evaluation of intracranial AVMs through comparison with DSA and time-of-flight (TOF) MRA. Nineteen patients (12 women, mean age 26.2±10.7 years) with intracranial AVMs were examined with 4D dMRA, TOF and DSA. Spetzler-Martin grading scale was evaluated using each of the above three methods independently by two raters. Diagnostic confidence scores for three components of AVMs (feeding artery, nidus and draining vein) were also rated. Kendall's coefficient of concordance was calculated to evaluate the reliability between two raters within each modality (dMRA, TOF, TOF plus dMRA). The Wilcoxon signed-rank test was applied to compare the diagnostic confidence scores between each pair of the three modalities. dMRA was able to detect 16 out of 19 AVMs, and the ratings of AVM size and location matched those of DSA. The diagnostic confidence scores by dMRA were adequate for nidus (3.5/5), moderate for feeding arteries (2.5/5) and poor for draining veins (1.5/5). The hemodynamic information provided by dMRA improved diagnostic confidence scores by TOF MRA. As a completely noninvasive method, 4D dMRA offers hemodynamic information with a temporal resolution of 50-100 ms for the evaluation of AVMs and can complement existing methods such as DSA and TOF MRA. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. Detection of hypervascular hepatocellular carcinoma: Comparison of multi-detector CT with digital subtraction angiography and Lipiodol CT

    PubMed Central

    Zheng, Xiao-Hua; Guan, Yong-Song; Zhou, Xiang-Ping; Huang, Juan; Sun, Long; Li, Xiao; Liu, Yuan

    2005-01-01

    AIM: The purpose of this study was to compare the diagnostic accuracy of biphasic multi-detector row helical computed tomography (MDCT), digital subtraction angiography (DSA) and Lipiodol computed tomography (CT) in detection of hypervascular hepatocellular carcinoma (HCC). METHODS: Twenty-eight patients with nodular HCC underwent biphasic MDCT examination: hepatic arterial phase (HAP) 25 s and portal venous phase (PVP) 70 s after injection of the contrast medium (1.5 mL/kg). They also underwent hepatic angiography and intra-arterial infusion of iodized oil. Lipiodol CT was performed 3-4 wk after infusion. MDCT images were compared with DSA and Lipiodol CT images for detection of hepatic nodules. RESULTS: The three imaging techniques had the same sensitivity in detecting nodules >20 mm in diameter. There was no significant difference in the sensitivity among HAP-MDCT, Lipiodol CT and DSA for nodules of 10-20 mm in diameter. For the nodules <10 mm in diameter, HAP-MDCT identified 47, Lipiodol CT detected 27 (χ2 = 11.3, P = 0.005<0.01, HAP-MDCT vs Lipiodol CT) and DSA detected 16 (χ2 = 9.09, P = 0.005<0.01 vs Lipiodol CT and χ2 = 29.03, P = 0.005<0.01vs HAP-MDCT). However, six nodules <10 mm in diameter were detected only by Lipiodol CT. CONCLUSION: MDCT and Lipiodol CT are two complementary modalities. At present, MDCT does not obviate the need for DSA and subsequent Lipiodol CT as a preoperative examination for HCC. PMID:15633215

  10. Intravascular ultrasound versus digital subtraction angiography: direct comparison of intraluminal diameter measurements in pediatric and adolescent imaging.

    PubMed

    Gill, Anne E; Ciszak, Tadi; Braun, Hayley; Hawkins, C Matthew

    2017-04-01

    Intravascular ultrasound (IVUS) allows intraluminal imaging of blood vessels rather than the one-dimensional luminal outline depicted by digital subtraction angiography (DSA). Despite extensive literature in multiple adult vascular diseases, IVUS has not been directly compared to DSA in pediatric and adolescent vascular pathologies. The purpose of this manuscript is to compare absolute luminal diameter measurements obtained via IVUS and DSA during a variety of pediatric endovascular procedures. We conducted a retrospective review of all pediatric and adolescent endovascular procedures from October 2014 to March 2016 in which IVUS and DSA were used. We compared the vessel diameter measurements and analyzed them using SAS software with a paired t-test. There were 102 total measurements (DSA = 56; IVUS = 56; 22 procedures; 20 patients). On average, IVUS measured 0.6 ± 2.1 mm larger than DSA (95% confidence interval [CI] -0.01 to 1.12; P = 0.06; r = 0.90). When venous compression syndrome (May-Thurner, Nutcracker, superior vena cava syndrome) measurements were excluded, IVUS measured 0.7 ± 1.6 mm larger than DSA (95% CI 0.14 to 1.18; P = 0.01; r = 0.93). When venous compression syndrome measurements were evaluated separately, IVUS measured 0.3 ± 3.0 mm larger than DSA (95% CI -1.16 to 1.82; P = 0.65; r = 0.45). Overall, IVUS measurements were slightly larger than DSA measurements in all data subsets. Absolute vessel diameter measurements obtained with IVUS in the pediatric and adolescent population are statistically significantly larger than those obtained using DSA when excluding venous compression syndromes. In venous compression syndromes, IVUS might provide a more accurate representation of vessel compression and diameter than DSA.

  11. Effect of injection technique on temporal parametric imaging derived from digital subtraction angiography in patient specific phantoms.

    PubMed

    Ionita, Ciprian N; Garcia, Victor L; Bednarek, Daniel R; Snyder, Kenneth V; Siddiqui, Adnan H; Levy, Elad I; Rudin, Stephen

    2014-03-13

    Parametric imaging maps (PIM's) derived from digital subtraction angiography (DSA) for the cerebral arterial flow assessment in clinical settings have been proposed, but experiments have yet to determine the reliability of such studies. For this study, we have observed the effects of different injection techniques on PIM's. A flow circuit set to physiologic conditions was created using an internal carotid artery phantom. PIM's were derived for two catheter positions, two different contrast bolus injection volumes (5ml and 10 ml), and four injection rates (5, 10, 15 and 20 ml/s). Using a gamma variate fitting approach, we derived PIM's for mean-transit-time (MTT), time-to-peak (TTP) and bolus-arrivaltime (BAT). For the same injection rates, a larger bolus resulted in an increased MTT and TTP, while a faster injection rate resulted in a shorter MTT, TTP, and BAT. In addition, the position of the catheter tip within the vasculature directly affected the PIM. The experiment showed that the PIM is strongly correlated with the injection conditions, and, therefore, they have to be interpreted with caution. PIM images must be taken from the same patient to be able to be meaningfully compared. These comparisons can include pre- and post-treatment images taken immediately before and after an interventional procedure or simultaneous arterial flow comparisons through the left and right cerebral hemispheres. Due to the strong correlation between PIM and injection conditions, this study indicates that this assessment method should be used only to compare flow changes before and after treatment within the same patient using the same injection conditions.

  12. Radiation dose and image quality of X-ray volume imaging systems: cone-beam computed tomography, digital subtraction angiography and digital fluoroscopy.

    PubMed

    Paul, Jijo; Jacobi, Volkmar; Farhang, Mohammad; Bazrafshan, Babak; Vogl, Thomas J; Mbalisike, Emmanuel C

    2013-06-01

    Radiation dose and image quality estimation of three X-ray volume imaging (XVI) systems. A total of 126 patients were examined using three XVI systems (groups 1-3) and their data were retrospectively analysed from 2007 to 2012. Each group consisted of 42 patients and each patient was examined using cone-beam computed tomography (CBCT), digital subtraction angiography (DSA) and digital fluoroscopy (DF). Dose parameters such as dose-area product (DAP), skin entry dose (SED) and image quality parameters such as Hounsfield unit (HU), noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were estimated and compared using appropriate statistical tests. Mean DAP and SED were lower in recent XVI than its previous counterparts in CBCT, DSA and DF. HU of all measured locations was non-significant between the groups except the hepatic artery. Noise showed significant difference among groups (P < 0.05). Regarding CNR and SNR, the recent XVI showed a higher and significant difference compared to its previous versions. Qualitatively, CBCT showed significance between versions unlike the DSA and DF which showed non-significance. A reduction of radiation dose was obtained for the recent-generation XVI system in CBCT, DSA and DF. Image noise was significantly lower; SNR and CNR were higher than in previous versions. The technological advancements and the reduction in the number of frames led to a significant dose reduction and improved image quality with the recent-generation XVI system. • X-ray volume imaging (XVI) systems are increasingly used for interventional radiological procedures. • More modern XVI systems use lower radiation doses compared with earlier counterparts. • Furthermore more modern XVI systems provide higher image quality. • Technological advances reduce radiation dose and improve image quality.

  13. Mask free intravenous 3D digital subtraction angiography (IV 3D-DSA) from a single C-arm acquisition

    NASA Astrophysics Data System (ADS)

    Li, Yinsheng; Niu, Kai; Yang, Pengfei; Aagaard-Kienitz, Beveley; Niemann, David B.; Ahmed, Azam S.; Strother, Charles; Chen, Guang-Hong

    2016-03-01

    Currently, clinical acquisition of IV 3D-DSA requires two separate scans: one mask scan without contrast medium and a filled scan with contrast injection. Having two separate scans adds radiation dose to the patient and increases the likelihood of suffering inadvertent patient motion induced mis-registration and the associated mis-registraion artifacts in IV 3D-DSA images. In this paper, a new technique, SMART-RECON is introduced to generate IV 3D-DSA images from a single Cone Beam CT (CBCT) acquisition to eliminate the mask scan. Potential benefits of eliminating mask scan would be: (1) both radiation dose and scan time can be reduced by a factor of 2; (2) intra-sweep motion can be eliminated; (3) inter-sweep motion can be mitigated. Numerical simulations were used to validate the algorithm in terms of contrast recoverability and the ability to mitigate limited view artifacts.

  14. Comparison of C-arm Computed Tomography and Digital Subtraction Angiography in Patients with Chronic Thromboembolic Pulmonary Hypertension

    SciTech Connect

    Hinrichs, Jan B. Marquardt, Steffen Falck, Christian von; Hoeper, Marius M. Olsson, Karen M.; Wacker, Frank K. Meyer, Bernhard C.

    2016-01-15

    PurposeTo assess the feasibility and diagnostic performance of contrast-enhanced, C-arm computed tomography (CACT) of the pulmonary arteries compared to digital subtraction angiography (DSA) in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH).MaterialsFifty-two patients with CTEPH underwent ECG-gated DSA and contrast-enhanced CACT. Two readers (R1, R2) independently evaluated pulmonary artery segments and their sub-segmental branching using DSA and CACT for optimal image quality. Afterwards, the diagnostic findings, i.e., intraluminal filling defects, stenosis, and occlusion, were compared. Inter-modality and inter-observer agreement was calculated, and subsequently consensus reading was done and correlated to a reference standard representing the overall consensus of both modalities. Fisher’s exact test and Cohen’s Kappa were applied.ResultsA total of 1352 pulmonary segments were evaluated, of which 1255 (92.8 %) on DSA and 1256 (92.9 %) on CACT were rated to be fully diagnostic. The main causes of the non-diagnostic image quality were motion artifacts on CACT (R1:37, R2:78) and insufficient contrast enhancement on DSA (R1:59, R2:38). Inter-observer agreement was good for DSA (κ = 0.74) and CACT (κ = 0.75), while inter-modality agreement was moderate (R1: κ = 0.46, R2: κ = 0.47). Compared to the reference standard, the inter-modality agreement for CACT was excellent (κ = 0.96), whereas it was inferior for DSA (κ = 0.61) due to the higher number of abnormal consensus findings read as normal on DSA.ConclusionCACT of the pulmonary arteries is feasible and provides additional information to DSA. CACT has the potential to improve the diagnostic work-up of patients with CTEPH and may be particularly useful prior to surgical or interventional treatment.

  15. Identification of Students' Intuitive Mental Computational Strategies for 1, 2 and 3 Digits Addition and Subtraction: Pedagogical and Curricular Implications

    ERIC Educational Resources Information Center

    Ghazali, Munirah; Alias, Rohana; Ariffin, Noor Asrul Anuar; Ayub, Ayminsyadora

    2010-01-01

    This paper reports on a study to examine mental computation strategies used by Year 1, Year 2, and Year 3 students to solve addition and subtraction problems. The participants in this study were twenty five 7 to 9 year-old students identified as excellent, good and satisfactory in their mathematics performance from a school in Penang, Malaysia.…

  16. Subtracted geometry

    NASA Astrophysics Data System (ADS)

    Saleem, Zain Hamid

    In this thesis we study a special class of black hole geometries called subtracted geometries. Subtracted geometry black holes are obtained when one omits certain terms from the warp factor of the metric of general charged rotating black holes. The omission of these terms allows one to write the wave equation of the black hole in a completely separable way and one can explicitly see that the wave equation of a massless scalar field in this slightly altered background of a general multi-charged rotating black hole acquires an SL(2, R) x SL(2, R) x SO(3) symmetry. The "subtracted limit" is considered an appropriate limit for studying the internal structure of the non-subtracted black holes because new 'subtracted' black holes have the same horizon area and periodicity of the angular and time coordinates in the near horizon regions as the original black hole geometry it was constructed from. The new geometry is asymptotically conical and is physically similar to that of a black hole in an asymptotically confining box. We use the different nice properties of these geometries to understand various classically and quantum mechanically important features of general charged rotating black holes.

  17. Using digital subtraction in computer simulated images as a tool to aid the visual detection of masked lesions in dense breasts

    NASA Astrophysics Data System (ADS)

    Schiabel, Homero; Guimarães, Luciana T.; Sousa, Maria A. Z.

    2015-03-01

    This work proposes a simulation model involving subtraction of digital mammography images obtained at different X-ray beam levels of energy to aid the detection of breast malignant lesions. Absorption coefficients behavior of 3 main structures of clinical interest - adipose tissue, fiber glandular tissue and the typical carcinoma - as a function of the beam energy from a Mo X-ray tube was the basis to develop a computer simulation of the possible acquired images. The simulation has considered a typical compressed breast with 4.5cm in thickness, and variations of the carcinoma and glandular tissues thicknesses - 0.4 up to 2.0cm and 4.1 to 2.5cm, respectively - were evaluated as a function of the photons mean energy - 14 up to 25 keV, in the typical mammography energy range. Results have shown that: (a) if the carcinoma thickness is over 0.4cm, its detection may be feasible even masked by fiber tissue with exposures in the range of 19 to 25 keV; (b) for masked carcinoma with thickness in the range of 0.4-2.0cm, the proposed procedure can enhance it in the image resulting from the digital subtraction between images obtained at 14 and at 22 keV. Therefore such results indicate that this simulation procedure can be a useful tool in aiding the identification of possible missed malignant lesions which could not be detected in the typical exam, mainly considering dense breasts.

  18. Effect of diabetes mellitus and insulin therapy on bone density around osseointegrated dental implants: a digital subtraction radiography study in rats.

    PubMed

    de Morais, Juliana Aparecida Najarro Dearo; Trindade-Suedam, Ivy Kiemle; Pepato, Maria Teresa; Marcantonio, Elcio; Wenzel, Ann; Scaf, Gulnara

    2009-08-01

    To evaluate the effect of diabetes mellitus (DM) and insulin therapy on bone density around osseointegrated dental implants by digital subtraction radiography (DSR). Forty implants were placed in tibiae of 40 adult rats. After a healing period of 2 months, the animals were divided into four groups of 10 animals each: a 2-month control group, sacrificed at time (A), a diabetic group (D), an insulin-treated group (I) and a 4-month control group (C). During 2 months, group I received subcutaneous doses of insulin, whereas groups C and D received only saline. The animals in groups D, I and C were thereafter sacrificed. The glucose plasma levels (GPLs) were monitored throughout the experiment. Film radiographs were taken at implant surgery and on the day of sacrifice. The radiographs were digitized, and bone density in regions of osseointegration (OR) around the implants was evaluated by quantitative DSR between baseline and final images. Differences in shades of gray among the groups were assessed using ANOVA. GPLs were within normal range for groups A, C and I and higher for group D. There was a significant difference in mean gray shade values in the OR of subtraction images between groups D (122+/-7) and I (136+/-5) (P<0.05) while there were no significant differences between control groups A (128+/-13) and C (134+/-10) and the insulin group I. DM impaired bone density around osseointegrated dental implant. Further, insulin therapy maintained bone density in diabetic rats.

  19. Use digital subtraction images of blue-light and near-infrared autofluorescence for the assessment of irregular foveal contour.

    PubMed

    Hua, Rui; Gangwani, Rita; Liu, Limin; Chen, Lei

    2015-01-01

    The aims of this study are to generate subtraction images of blue-light autofluorescence (BL-AF) and near-infrared autofluorescence (NIR-AF) from normal eyes, eyes with full thickness macular holes, and eyes with irregular foveal contour, and to compare their autofluorescence patterns. This retrospective study included 44 normal eyes of 22 health individuals, 32 eyes with full thickness macular holes of 32 patients, and 36 eyes with irregular foveal contour of 36 patients. BL-AF and NIR-AF were obtained from all patients and used to generate subtraction images using the Image J software. The decreased signal of central patch was recorded. The central foveal thickness (CFT) and outer nucleus layer (ONL) thickness of fovea were measured to calculate the ONL thickness/CFT ratio. The subtraction images showed regularly increased signal in the central macula of all normal eyes. In contrast, decreased signal of central patch was detected in all full thickness macular holes eyes and 26 out of 36 eyes with irregular foveal contour. No significant difference of the ONL thickness/CFT ratio (F = 2.32, P = 0.113) was observed between normal and irregular foveal contour eyes with or without decreased signal of central patch. Both regularly increased signal and decreased signal of central patch were detected in the eyes with irregular foveal contour. Our results suggest that subtraction images are useful for the assessment of certain macular conditions by providing supplementary information to the green-light autofluorescence and BL-AF.

  20. Intravenous DSA of extracranial carotid lesions: comparison with other techniques and specimens

    SciTech Connect

    Sheldon, J.J.; Janowitz, W.; Leborgne, J.M.; Sivina, M.; Rojo, N.

    1984-12-01

    Intravenous digital subtraction arteriography (DSA) was performed in 306 patients with suspected ischemic cerebrovascular disease. Forty-eight carotid endarterectomies were performed in 43 of these patients. The percentage stenosis as determined on the intravenous DSA examination concurred with the surgical findings in 83.3%. Nine surgical lesions had both intravenous DSA and conventional arteriography. Intravenous DSA was correct in six and arteriography in seven of these lesions. There were four surgically confirmed ulcerations. Two were evaluated by intravenous DSA alone. Two had intravenous DSA and arteriography. Thirty-seven surgical lesions had both intravenous DSA and high-resolution real-time sonographic imaging. Sonography agreed in 67.5% and intravenous DSA in 83.7% of these lesions. When an abnormal supraorbital Doppler or an abnormal oculopneumoplethysmography/Gee examination is added to the sonographic examination, an overall sensitivity of 93% was obtained in detecting a surgical lesion.

  1. Tuckshop Subtraction

    ERIC Educational Resources Information Center

    Duke, Roger; Graham, Alan; Johnston-Wilder, Sue

    2007-01-01

    This article describes a recent and successful initiative on teaching place value and the decomposition method of subtraction to pupils having difficulty with this technique in the 9-12-year age range. The aim of the research was to explore whether using the metaphor of selling chews (i.e., sweets) in a tuck shop and developing this into an iconic…

  2. Tuckshop Subtraction

    ERIC Educational Resources Information Center

    Duke, Roger; Graham, Alan; Johnston-Wilder, Sue

    2007-01-01

    This article describes a recent and successful initiative on teaching place value and the decomposition method of subtraction to pupils having difficulty with this technique in the 9-12-year age range. The aim of the research was to explore whether using the metaphor of selling chews (i.e., sweets) in a tuck shop and developing this into an iconic…

  3. A novel approach to background subtraction in contrast-enhanced dual-energy digital mammography with commercially available mammography devices: Polychromaticity correction.

    PubMed

    Contillo, Adriano; Di Domenico, Giovanni; Cardarelli, Paolo; Gambaccini, Mauro; Taibi, Angelo

    2015-11-01

    Contrast-enhanced digital mammography is an image subtraction technique that is able to improve the detectability of lesions in dense breasts. One of the main sources of error, when the technique is performed by means of commercial mammography devices, is represented by the intrinsic polychromaticity of the x-ray beams. The aim of the work is to propose an iterative procedure, which only assumes the knowledge of a small set of universal quantities, to take into account the polychromaticity and correct the subtraction results accordingly. In order to verify the procedure, it has been applied to an analytical simulation of a target containing a contrast medium and to actual radiographs of a breast phantom containing cavities filled with a solution of the same medium. The reconstructed densities of contrast medium were compared, showing very good agreement between the theoretical predictions and the experimental results already after the first iteration. Furthermore, the convergence of the iterative procedure was studied, showing that only a small number of iterations is necessary to reach limiting values. The proposed procedure represents an efficient solution to the polychromaticity issue, qualifying therefore as a viable alternative to inverse-map functions.

  4. A novel approach to background subtraction in contrast-enhanced dual-energy digital mammography with commercially available mammography devices: Polychromaticity correction

    SciTech Connect

    Contillo, Adriano Di Domenico, Giovanni; Cardarelli, Paolo; Gambaccini, Mauro; Taibi, Angelo

    2015-11-15

    Purpose: Contrast-enhanced digital mammography is an image subtraction technique that is able to improve the detectability of lesions in dense breasts. One of the main sources of error, when the technique is performed by means of commercial mammography devices, is represented by the intrinsic polychromaticity of the x-ray beams. The aim of the work is to propose an iterative procedure, which only assumes the knowledge of a small set of universal quantities, to take into account the polychromaticity and correct the subtraction results accordingly. Methods: In order to verify the procedure, it has been applied to an analytical simulation of a target containing a contrast medium and to actual radiographs of a breast phantom containing cavities filled with a solution of the same medium. Results: The reconstructed densities of contrast medium were compared, showing very good agreement between the theoretical predictions and the experimental results already after the first iteration. Furthermore, the convergence of the iterative procedure was studied, showing that only a small number of iterations is necessary to reach limiting values. Conclusions: The proposed procedure represents an efficient solution to the polychromaticity issue, qualifying therefore as a viable alternative to inverse-map functions.

  5. Elementary subtraction.

    PubMed

    Seyler, Donald J; Kirk, Elizabeth P; Ashcraft, Mark H

    2003-11-01

    Four experiments examined performance on the 100 "basic facts" of subtraction and found a discontinuous "stair step" function for reaction times and errors beginning with 11 - n facts. Participants' immediate retrospective reports of nonretrieval showed the same pattern in Experiment 3. The degree to which elementary subtraction depends on working memory (WM) was examined in a dual-task paradigm in Experiment 4. The reconstructive processing used with larger basic facts was strongly associated with greater WM disruption, as evidenced by errors in the secondary task: this was especially the case for participants with lower WM spans. The results support the R. S. Siegler and E. Jenkins (1989) distribution of associations model, although discriminating among the alternative solution processes appears to be a serious challenge.

  6. Tests of variable-band multilayers designed for investigating optimal signal-to-noise vs artifact signal ratios in Dual-Energy Digital Subtraction Angiography (DDSA) imaging systems

    SciTech Connect

    Boyers, D.; Ho, A.; Li, Q.; Piestrup, M.; Rice, M.; Tatchyn, R.

    1993-08-01

    In recent work, various design techniques were applied to investigate the feasibility of controlling the bandwidth and bandshape profiles of tungsten/boron-carbon (W/B{sub 4}C) and tungsten/silicon (W/Si) multilayers for optimizing their performance in synchrotron radiation based angiographical imaging systems at 33 keV. Varied parameters included alternative spacing geometries, material thickness ratios, and numbers of layer pairs. Planar optics with nominal design reflectivities of 30%--94% and bandwidths ranging from 0.6%--10% were designed at the Stanford Radiation Laboratory, fabricated by the Ovonic Synthetic Materials Company, and characterized on Beam Line 4-3 at the Stanford Synchrotron Radiation Laboratory, in this paper we report selected results of these tests and review the possible use of the multilayers for determining optimal signal to noise vs. artifact signal ratios in practical Dual-Energy Digital Subtraction Angiography systems.

  7. [Clinical values of hemodynamics assessment by parametric color coding of digital subtraction angiography before and after endovascular therapy for critical limb ischaemia].

    PubMed

    Su, Haobo; Lou, Wensheng; Gu, Jianping

    2015-10-06

    To investigate the feasibility of parametric color coding of digital subtraction angiography (Syngo iFlow) for hemodynamics assessment in patients with critical limb ischemia in pre- and post-endovascular therapy. To explore the correlation between Syngo iFlow and the conventional techniques. from January 2013 to December 2014, Clinical data of 21 patients with TASC II type B and type C femoropopliteal arteriosclerotic occlusive disease who were treated by percutaneous transluminal angioplasty and/or primary stent implantation in Nanjing first hospital were analyzed retrospectively. Of these patients there were 10 males and 11 females with an average age of (72±6) years (range from 58-85 years). The treatment efficacy was assessed by the variation of a series of clinical symptoms indexes (such as pain score, cold sensation score and intermittent claudication score), ankle braehial index (ABI) and transcutaneous oxygen pressure (TcPO2). Angiography was performed with the same protocol before and after treatment and parametric color coding of digital subtraction angiography was created by Syngo iFlow software on a dedicated workstation. The time to peak (TTP) of artery and tissue perfusion selected at the same regions of foot and ankle were measured and analyzed to evaluate the improvement of microcirculation and hemodynamics of the ischemic limb. The correlations between Syngo iFlow and the traditional clinical evaluation methods were explored using the Spearman rank correlation test. All patients (21 limbs) underwent successful endovaseular therapy. The mean pain score, cold sensation score, intermittent claudication score, ABI and TcPO2 before treatment were (0.48±0.68), (2.71±0.72), (2.86±0.85), ABI (0.33±0.07), TcPO2 (26.83±3.41) mmHg. While 1 week after treatment all above indicators were (2.57±0.93), (0.33±0.48), (0.90±0.54), (0.69±0.11), TcPO2 (53.75±3.60) mmHg respectively. There were significant statistical differences between pre- and post

  8. Comparison of changes in dental and bone radiographic densities in the presence of different soft-tissue simulators using pixel intensity and digital subtraction analyses

    PubMed Central

    de Molon, R S; Batitucci, R G; Spin-Neto, R; Paquier, G M; Sakakura, C E; Tosoni, G M

    2013-01-01

    Objectives: To evaluate the influence of soft-tissue simulation materials on dental and bone tissue radiographic densities using pixel intensity (PI) and digital subtraction radiography (DSR) analyses. Methods: 15 dry human mandibles were divided into halves. Each half was radiographed using a charge-coupled device sensor without a soft-tissue simulation material (Wm) and with 5 types of materials: acrylic (Ac), wax (Wx), water (Wt), wood (Wd) and frozen bovine tissue (Bt). Three thicknesses were tested for each material: 10 mm, 15 mm and 20 mm. The material was positioned in front of the mandible and the sensor parallel to the molar region. The radiation beam was perpendicular to the sensor at 30 cm focal spot-to-object distance. The digital images of the bone and dental tissue were captured for PI analyses. The subtracted images were marked with 14 landmark magnifications, and 2 areas of analyses were defined, forming the regions of interest. Shapiro–Wilk and Kruskal–Wallis tests followed by Dunn's post-test were used (p < 0.05). Results: DSR showed that both the material type and the thickness tested influenced the gain of density in bone tissue (p < 0.05). PI analyses of the bone region did not show these differences, except for the lower density observed in the image without soft-tissue simulation material. In the dental region, both DSR and PI showed that soft-tissue simulators did not influence the density in these regions. Conclusions: This study showed that the materials evaluated and their thicknesses significantly influenced the density-level gain in alveolar bone. In dental tissues, there was no density-level gain with any soft-tissue material tested. PMID:24005061

  9. Comparison of changes in dental and bone radiographic densities in the presence of different soft-tissue simulators using pixel intensity and digital subtraction analyses.

    PubMed

    de Molon, R S; Batitucci, R G; Spin-Neto, R; Paquier, G M; Sakakura, C E; Tosoni, G M; Scaf, G

    2013-01-01

    To evaluate the influence of soft-tissue simulation materials on dental and bone tissue radiographic densities using pixel intensity (PI) and digital subtraction radiography (DSR) analyses. 15 dry human mandibles were divided into halves. Each half was radiographed using a charge-coupled device sensor without a soft-tissue simulation material (Wm) and with 5 types of materials: acrylic (Ac), wax (Wx), water (Wt), wood (Wd) and frozen bovine tissue (Bt). Three thicknesses were tested for each material: 10 mm, 15 mm and 20 mm. The material was positioned in front of the mandible and the sensor parallel to the molar region. The radiation beam was perpendicular to the sensor at 30 cm focal spot-to-object distance. The digital images of the bone and dental tissue were captured for PI analyses. The subtracted images were marked with 14 landmark magnifications, and 2 areas of analyses were defined, forming the regions of interest. Shapiro-Wilk and Kruskal-Wallis tests followed by Dunn's post-test were used (p < 0.05). DSR showed that both the material type and the thickness tested influenced the gain of density in bone tissue (p < 0.05). PI analyses of the bone region did not show these differences, except for the lower density observed in the image without soft-tissue simulation material. In the dental region, both DSR and PI showed that soft-tissue simulators did not influence the density in these regions. This study showed that the materials evaluated and their thicknesses significantly influenced the density-level gain in alveolar bone. In dental tissues, there was no density-level gain with any soft-tissue material tested.

  10. Behavior subtraction.

    PubMed

    Jodoin, Pierre-Marc; Saligrama, Venkatesh; Konrad, Janusz

    2012-09-01

    Background subtraction has been a driving engine for many computer vision and video analytics tasks. Although its many variants exist, they all share the underlying assumption that photometric scene properties are either static or exhibit temporal stationarity. While this works in many applications, the model fails when one is interested in discovering changes in scene dynamics instead of changes in scene's photometric properties; the detection of unusual pedestrian or motor traffic patterns are but two examples. We propose a new model and computational framework that assume the dynamics of a scene, not its photometry, to be stationary, i.e., a dynamic background serves as the reference for the dynamics of an observed scene. Central to our approach is the concept of an event, which we define as short-term scene dynamics captured over a time window at a specific spatial location in the camera field of view. Unlike in our earlier work, we compute events by time-aggregating vector object descriptors that can combine multiple features, such as object size, direction of movement, speed, etc. We characterize events probabilistically, but use low-memory, low-complexity surrogates in a practical implementation. Using these surrogates amounts to behavior subtraction, a new algorithm for effective and efficient temporal anomaly detection and localization. Behavior subtraction is resilient to spurious background motion, such as due to camera jitter, and is content-blind, i.e., it works equally well on humans, cars, animals, and other objects in both uncluttered and highly cluttered scenes. Clearly, treating video as a collection of events rather than colored pixels opens new possibilities for video analytics.

  11. Real-time out-of-plane artifact subtraction tomosynthesis imaging using prior CT for scanning beam digital x-ray system

    SciTech Connect

    Wu, Meng; Fahrig, Rebecca

    2014-11-01

    Purpose: The scanning beam digital x-ray system (SBDX) is an inverse geometry fluoroscopic system with high dose efficiency and the ability to perform continuous real-time tomosynthesis in multiple planes. This system could be used for image guidance during lung nodule biopsy. However, the reconstructed images suffer from strong out-of-plane artifact due to the small tomographic angle of the system. Methods: The authors propose an out-of-plane artifact subtraction tomosynthesis (OPAST) algorithm that utilizes a prior CT volume to augment the run-time image processing. A blur-and-add (BAA) analytical model, derived from the project-to-backproject physical model, permits the generation of tomosynthesis images that are a good approximation to the shift-and-add (SAA) reconstructed image. A computationally practical algorithm is proposed to simulate images and out-of-plane artifacts from patient-specific prior CT volumes using the BAA model. A 3D image registration algorithm to align the simulated and reconstructed images is described. The accuracy of the BAA analytical model and the OPAST algorithm was evaluated using three lung cancer patients’ CT data. The OPAST and image registration algorithms were also tested with added nonrigid respiratory motions. Results: Image similarity measurements, including the correlation coefficient, mean squared error, and structural similarity index, indicated that the BAA model is very accurate in simulating the SAA images from the prior CT for the SBDX system. The shift-variant effect of the BAA model can be ignored when the shifts between SBDX images and CT volumes are within ±10 mm in the x and y directions. The nodule visibility and depth resolution are improved by subtracting simulated artifacts from the reconstructions. The image registration and OPAST are robust in the presence of added respiratory motions. The dominant artifacts in the subtraction images are caused by the mismatches between the real object and the prior CT

  12. Visualization and quantitation of coronary arteries using multiple-view energy subtraction digital radiography. Interim report 30 September 1983-29 September 1984

    SciTech Connect

    Macovski, A.

    1984-08-27

    The authors have studied a general approach to the imaging of coronary arteries using minimally invasive intravenous administration of contrast material. Using conventional DSA techniques this visualization would fail due to motion, low SNR, and intervening iodinated structures. The authors have implemented the digital fluoroscopy system with a rotating gantry and tested it on phantoms. Evaluation of stenosis in coronary arteries is difficult with low SNR images. The authors have studied and implemented a vessel outlining system using a global estimation procedure. The most recent approach has significantly improved computational efficiency. The processing of multiple-energy data to eliminate the moving soft tissue results in a noise penalty. The authors have studied and implemented an approach to restore the original SNR by deriving the high frequency components from a non-selective image. The authors have also implemented a scatter-cancellation system for minimizing this source of error.

  13. Contexts for Column Addition and Subtraction

    ERIC Educational Resources Information Center

    Lopez Fernandez, Jorge M.; Velazquez Estrella, Aileen

    2011-01-01

    In this article, the authors discuss their approach to column addition and subtraction algorithms. Adapting an original idea of Paul Cobb and Erna Yackel's from "A Contextual Investigation of Three-Digit Addition and Subtraction" related to packing and unpacking candy in a candy factory, the authors provided an analogous context by…

  14. Contexts for Column Addition and Subtraction

    ERIC Educational Resources Information Center

    Lopez Fernandez, Jorge M.; Velazquez Estrella, Aileen

    2011-01-01

    In this article, the authors discuss their approach to column addition and subtraction algorithms. Adapting an original idea of Paul Cobb and Erna Yackel's from "A Contextual Investigation of Three-Digit Addition and Subtraction" related to packing and unpacking candy in a candy factory, the authors provided an analogous context by…

  15. Non-contrast-enhanced MR angiography in the diagnosis of Budd-Chiari syndrome (BCS) compared with digital subtraction angiography (DSA): Preliminary results.

    PubMed

    Yang, Chun; Li, Ceng; Zeng, Mengsu; Lu, Xin; Li, Jingjing; Wang, Jiali; Sami, Muhammad Umair; Xu, Kai

    2017-02-01

    Non-CE MRA techniques (true steady-state free-precession, SSFP) have been used effectively for the selective visualization of the portal venous system and inferior vena cava. Budd-Chiari Syndrome (BCS) encompasses a number of conditions that cause the obstruction of the hepatic outflow tract from the small hepatic veins to the junction of the inferior vena cava (IVC) and right atrium. The purpose of this study was to diagnose BCS with IVC obstruction using respiratory triggered three-dimensional (3D) true SSFP with T-SLIP and compare to digital subtraction angiography (DSA). The image acquisition of 3D true SSFP scans was successfully performed in 108 patients (≧2 score). The mean and SDs of the relative SNR and CNR were 55.96±2.32 and 30.72±1.56, respectively. Intergroup agreement for the detection of the 4 types (membranous obstruction, segmental occlusion, and membranous obstruction with a hole and segmental stenosis) of BCS with IVC obstruction was excellent between the Time-SLIP and the DSA. In conclusion, Time-SLIP for the detection of IVC obstruction BCS does not require the use of contrast. This procedure can achieve a high success rate, high accuracy rate and fine image quality for the diagnosis of IVC obstruction BCS. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Efficacy of sclerotherapy with radio-opaque foam guided by digital subtraction angiography for the treatment of complex venous malformations of the head and neck.

    PubMed

    Chen, A-W; Liu, Y-R; Li, K; Zhang, K; Wang, T; Liu, S-H

    2015-11-01

    Our aim was to evaluate the efficacy of sclerotherapy using radio-opaque foam and guided by digital subtraction angiography (DSA) for complex venous malformations in the head and neck in 11 selected patients between 2011 and 2013. The sclerosing foam was manufactured by the classic Tessari method and consisted of air, 1% polidocanol, and radio-opaque media iopromide (Ultravist(®)300) in a ratio of 7:2:1. We recorded the site and size of the lesion, time and duration of treatment, and therapeutic response. The lesions were on the face, cheek, temporal region, parotid region, neck, tongue, floor of the mouth, parapharyngeal space, and soft palate. The sclerosing foam was radio-opaque under DSA, and the mean (range) dose was 21 (3-65) ml. A mean (range) of 4 (2-7) treatments was required, and 10 of the 11 patients responded well. In 4 of the 11 cases the lesion resolved completely and in 6 there was a good response. Only one lesion recurred. Early complications included immediate swelling in injected areas, snoring, and pain on swallowing, but there were no air emboli or signs of cutaneous necrosis, and the complications were self-limiting. DSA-guided sclerotherapy with radio-opaque foam was safe and effective for the treatment of complex vascular malformations of the head and neck. Copyright © 2015 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  17. Role of image fusion combining three-dimensional digital subtraction angiography with magnetic resonance imaging in evaluation of unruptured cerebral aneurysms.

    PubMed

    Suzuki, Hidenori; Shimizu, Shigetoshi; Maki, Hiroaki; Maeda, Masayuki; Sakaida, Hiroshi; Trousset, Yves; Taki, Waro

    2007-01-01

    The goal of this study was to evaluate the usefulness of a recently developed image fusion of three-dimensional digital subtraction angiography (3D DSA) and magnetic resonance (MR) images, DSA-MR fusion, in the pre-treatment assessment of cerebral aneurysm. Eighteen patients with 21 unruptured anterior or posterior circulation aneurysms underwent pre-treatment DSA-MR fusion. The authors independently assessed whether DSA-MR fusion images provided any useful additional information compared with analysing 3D DSA and MR images separately, and if this had an impact on the therapeutic decision-making of unruptured aneurysms. DSA-MR fusion images were obtained within 30 minutes for all patients. In 19 of 21 aneurysms, it provided the following additional information to the findings of 3D DSA, MR images or both: the passing course in the brain tissues of perforating arteries near or originating from an aneurysm, and/or the spatial relationship between an aneurysm and an oculomotor nerve. This information from DSA-MR fusion images was useful for diagnosis, therapeutic decision-making and the risk assessment associated with the treatment, as well as patient education regarding cerebral aneurysm. DSA-MR fusion images were useful for the pre-treatment evaluation of unruptured cerebral aneurysms as a supplement to DSA and MR images.

  18. Flow modification in canine intracranial aneurysm model by an asymmetric stent: studies using digital subtraction angiography (DSA) and image-based computational fluid dynamics (CFD) analyses

    NASA Astrophysics Data System (ADS)

    Hoi, Yiemeng; Ionita, Ciprian N.; Tranquebar, Rekha V.; Hoffmann, Kenneth R.; Woodward, Scott H.; Taulbee, Dale B.; Meng, Hui; Rudin, Stephen

    2006-03-01

    An asymmetric stent with low porosity patch across the intracranial aneurysm neck and high porosity elsewhere is designed to modify the flow to result in thrombogenesis and occlusion of the aneurysm and yet to reduce the possibility of also occluding adjacent perforator vessels. The purposes of this study are to evaluate the flow field induced by an asymmetric stent using both numerical and digital subtraction angiography (DSA) methods and to quantify the flow dynamics of an asymmetric stent in an in vivo aneurysm model. We created a vein-pouch aneurysm model on the canine carotid artery. An asymmetric stent was implanted at the aneurysm, with 25% porosity across the aneurysm neck and 80% porosity elsewhere. The aneurysm geometry, before and after stent implantation, was acquired using cone beam CT and reconstructed for computational fluid dynamics (CFD) analysis. Both steady-state and pulsatile flow conditions using the measured waveforms from the aneurysm model were studied. To reduce computational costs, we modeled the asymmetric stent effect by specifying a pressure drop over the layer across the aneurysm orifice where the low porosity patch was located. From the CFD results, we found the asymmetric stent reduced the inflow into the aneurysm by 51%, and appeared to create a stasis-like environment which favors thrombus formation. The DSA sequences also showed substantial flow reduction into the aneurysm. Asymmetric stents may be a viable image guided intervention for treating intracranial aneurysms with desired flow modification features.

  19. Routine Use of Three-Dimensional Contrast-Enhanced Moving-Table MR Angiography in Patients with Peripheral Arterial Occlusive Disease: Comparison with Selective Digital Subtraction Angiography

    SciTech Connect

    Deutschmann, Hannes A.; Schoellnast, Helmut; Portugaller, Horst R.; Preidler, Klaus W.; Reittner, Pia; Tillich, Manfred; Pilger, Ernst; Szolar, Dieter H. M.

    2006-10-15

    Purpose. To compare the diagnostic accuracy of contrast-enhanced (CE) three-dimensional (3D) moving-table magnetic resonance (MR) angiography with that of selective digital subtraction angiography (DSA) for routine clinical investigation in patients with peripheral arterial occlusive disease. Methods. Thirty-eight patients underwent CE 3D moving-table MR angiography of the pelvic and peripheral arteries. A commercially available large-field-of-view adapter and a dedicated peripheral vascular phased-array coil were used. MR angiograms were evaluated for grade of arterial stenosis, diagnostic quality, and presence of artifacts. MR imaging results for each patient were compared with those of selective DSA. Results. Two hundred and twenty-six arterial segments in 38 patients were evaluated by both selective DSA and MR angiography. No complications related to MR angiography were observed. There was agreement in stenosis classification in 204 (90.3%) segments; MR angiography overgraded 16 (7%) segments and undergraded 6 (2.7%) segments. Compared with selective DSA, MR angiography provided high sensitivity and specificity and excellent interobserver agreement for detection of severe stenosis (97% and 95%, {kappa} = 0.9 {+-} 0.03) and moderate stenosis (96.5% and 94.3%, {kappa} = 0.9 {+-} 0.03). Conclusion. Compared with selective DSA, moving-table MR angiography proved to be an accurate, noninvasive method for evaluation of peripheral arterial occlusive disease and may thus serve as an alternative to DSA in clinical routine.

  20. NOTE: Suppression of high-density artefacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

    NASA Astrophysics Data System (ADS)

    Baissalov, R.; Sandison, G. A.; Donnelly, B. J.; Saliken, J. C.; McKinnon, J. G.; Muldrew, K.; Rewcastle, J. C.

    2000-05-01

    Image guidance in cryotherapy is usually performed using ultrasound. Although not currently in routine clinical use, x-ray CT imaging is an alternative means of guidance that can display the full 3D structure of the iceball, including frozen and unfrozen regions. However, the quality of x-ray CT images is compromised by the presence of high-density streak artefacts. To suppress these artefacts we applied temporal digital subtraction (TDS). This TDS method has the added advantage of improving the grey-scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high-density artefacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced artefact content. Thus TDS can be used to significantly suppress or eliminate high-density CT streak artefacts without reducing the metallic content of the cryoprobes. In vivo study needs to be conducted to establish the utility of this TDS procedure for CT assisted prostate or liver cryotherapy. Applying TDS in x-ray CT guided cryotherapy will facilitate estimation of the number and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent.

  1. TU-CD-207-03: Time Evolution of Texture Parameters of Subtracted Images Obtained by Contrast-Enhanced Digital Mammography (CEDM)

    SciTech Connect

    Mateos, M-J; Brandan, M-E; Gastelum, A; Marquez, J

    2015-06-15

    Purpose: To evaluate the time evolution of texture parameters, based on the gray level co-occurrence matrix (GLCM), in subtracted images of 17 patients (10 malignant and 7 benign) subjected to contrast-enhanced digital mammography (CEDM). The goal is to determine the sensitivity of texture to iodine uptake at the lesion, and its correlation (or lack of) with mean-pixel-value (MPV). Methods: Acquisition of clinical images followed a single-energy CEDM protocol using Rh/Rh/48 kV plus external 0.5 cm Al from a Senographe DS unit. Prior to the iodine-based contrast medium (CM) administration a mask image was acquired; four CM images were obtained 1, 2, 3, and 5 minutes after CM injection. Temporal series were obtained by logarithmic subtraction of registered CM minus mask images.Regions of interest (ROI) for the lesion were drawn by a radiologist and the texture was analyzed. GLCM was evaluated at a 3 pixel distance, 0° angle, and 64 gray-levels. Pixels identified as registration errors were excluded from the computation. 17 texture parameters were chosen, classified according to similarity into 7 groups, and analyzed. Results: In all cases the texture parameters within a group have similar dynamic behavior. Two texture groups (associated to cluster and sum mean) show a strong correlation with MPV; their average correlation coefficient (ACC) is r{sup 2}=0.90. Other two groups (contrast, homogeneity) remain constant with time, that is, a low-sensitivity to CM uptake. Three groups (regularity, lacunarity and diagonal moment) are sensitive to CM uptake but less correlated with MPV; their ACC is r{sup 2}=0.78. Conclusion: This analysis has shown that, at least groups associated to regularity, lacunarity and diagonal moment offer dynamical information additional to the mean pixel value due to the presence of CM at the lesion. The next step will be the analysis in terms of the lesion pathology. Authors thank PAPIIT-IN105813 for support. Consejo Nacional de Ciencia Y

  2. SUCCESSFUL TREATMENT OF DIGITAL OSTEITIS BY INTRAVENOUS REGIONAL PERFUSION OF CEFTIOFUR IN AN AFRICAN ELEPHANT (LOXODONTA AFRICANA).

    PubMed

    Dutton, Christopher J; Delnatte, Pauline G; Hollamby, Simon R; Crawshaw, Graham J

    2017-06-01

    A 41-yr-old African elephant ( Loxodonta africana ) presented with a swollen third digit of the left forelimb and a 2-cm hole in the pad. Corrective trimming, topical treatments, and an oral antibiotic resulted in apparent resolution; however, it reoccurred after 4 mo. Radiographs suggested bone lysis in the third phalanx, with the primary differential diagnosis being septic osteitis. Flushing with metronidazole solution and intravenous regional perfusion (IVRP) of the foot were commenced. A tourniquet was applied just above the carpus, an interdigital vein was identified by ultrasound, and into this vein 2 g (20 ml) of ceftiofur sodium solution, followed by 60 ml of heparinized saline, was administered. The foot was kept raised for 25 min and then the tourniquet was removed. IVRP was repeated every other day for 70 treatments over 6 mo. Healing occurred, which was confirmed radiographically. IVRP offers an excellent treatment modality in a well-trained elephant.

  3. Nonenhanced ECG-gated quiescent-interval single shot MRA: image quality and stenosis assessment at 3 tesla compared with contrast-enhanced MRA and digital subtraction angiography.

    PubMed

    Hansmann, Jan; Morelli, John N; Michaely, Henrik J; Riester, Thomas; Budjan, Johannes; Schoenberg, Stefan O; Attenberger, Ulrike I

    2014-06-01

    To evaluate the diagnostic accuracy of a nonenhanced electrocardiograph-gated quiescent-interval single shot MR-angiography (QISS-MRA) at 3 Tesla with contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA) serving as reference standard. Following institutional review board approval, 16 consecutive patients with peripheral arterial disease underwent a combined peripheral MRA protocol consisting of a large field-of-view QISS-MRA, continuous table movement MRA, and an additional time-resolved MRA of the calves. DSA correlation was available in eight patients. Image quality and degree of stenosis was assessed. Sensitivity and specificity of QISS-MRA was evaluated with CE-MRA and DSA serving as the standards of reference and compared using the Fisher exact test. With the exception of the calf station, image quality with QISS-MRA was rated statistically significantly less than that of CE-MRA (P < 0.05, P = 0.17, and P = 0.6, respectively). A greater percentage of segments were not accessible with QISS-MRA (19.5-20.1%) in comparison to CE-MRA (10.9%). Relative to DSA, sensitivity for QISS-MRA was high (100% versus 91.2% for CE-MRA, P = 0.24) in the evaluated segments; however, specificity (76.5%) was substantially less than that of CE-MRA (94.6%, P = 0.003). Overall image quality and specificity of QISS-MRA at 3T are diminished relative to CE-MRA. However, when image quality is adequate, QISS-MRA has high sensitivity and, thus, has potential use in patients with contraindications to gadolinium. Copyright © 2013 Wiley Periodicals, Inc.

  4. Apical Transportation, Centering Ratio, and Volume Increase after Manual, Rotary, and Reciprocating Instrumentation in Curved Root Canals: Analysis by Micro-computed Tomographic and Digital Subtraction Radiography.

    PubMed

    Zanesco, Caroline; Só, Marcus Vinicius Reis; Schmidt, Sabrina; Fontanella, Vania Regina Camargo; Grazziotin-Soares, Renata; Barletta, Fernando Branco

    2017-03-01

    This study aimed to evaluate apical transportation (AT), centering ratio (CR), and volume increase (VI) produced after instrumentation of mesiobuccal canals of maxillary molars with hand files, rotary, and reciprocating instruments using micro-computed tomographic (micro-CT) imaging and to demonstrate the ability of digital subtraction radiography (DSR) to evaluate AT. Forty-five canals were randomly assigned to either group K, manual K-files; PTN, ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland); or Rec, Reciproc (n = 15 for each group) for preparation. Master apical files were #25, X2 (#25/06), and R25 (#25/08), respectively. Micro-CT imaging was used to measure AT (mm) and CR (mm) at 3 different locations (1, 4, and 7 mm from the apex). VI (mm(3)) was measured for each root third and for the whole canal. DSR (mesiodistal and buccolingual projections) was used to measure AT at 1 mm from the apex. AT and CR values were statistically similar across the groups at 1, 4, and 7 mm. AT results obtained for the different locations were similar within each group; CR, in turn, showed statistically lower values at 1 mm. VI was statistically similar in all groups. Both DSR and micro-CT imaging showed that AT always occurred on the outside of canal curvature. The highest mean value obtained for AT was 0.215 mm. AT, CR, and VI were similar for the K, PTN, and Rec groups. AT results were clinically irrelevant. DSR was as effective as micro-CT imaging in AT analysis and could be considered as an alternative method for assessing this outcome. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  5. Non-enhanced, ECG-gated MR angiography of the pedal vasculature: comparison with contrast-enhanced MR angiography and digital subtraction angiography in peripheral arterial occlusive disease.

    PubMed

    Schubert, Tilman; Takes, Martin; Aschwanden, Markus; Klarhoefer, Markus; Haas, Tanja; Jacob, Augustinus L; Liu, David; Gutzeit, Andreas; Kos, Sebastian

    2016-08-01

    This study was conducted in order to compare a high resolution, non-contrast-enhanced MRA (NATIVE SPACE, NE-MRA) of the pedal vasculature with contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA) in patients with peripheral arterial occlusive disease (PAOD). The prospective study consists of 20 PAOD patients. All patients underwent percutaneous transluminal angioplasty or stenting and received MR angiographies the following day. With CE-MRA, 75.7 % of vessel segments showed good, 16.4 % suboptimal and 7.9 % not usable image quality. With NE-MRA, 64.6 % showed good, 18.6 % suboptimal and 16.8 % not usable image quality. CE-MRA showed a sensitivity and negative predictive value of 90 %/95 % regarding significant stenosis (greater than 50 %), and specificity and positive predictive value were 88 %/77 %. Accordingly, sensitivity and negative predictive value for the NE-MRA were 96 %/97 % and specificity and positive predictive value were 80 %/69 % for stenoses greater than 50 %. The applied NE-MRA technique achieves high diagnostic accuracy even in very small distal arteries of the foot. However, the rate of non-diagnostic vessel segments is considerably higher for NE-MRA than for CE-MRA. NE-MRA is a valuable alternative to CE-MRA in selected patients. • Comparison of non-enhanced MRA with contrast-enhanced MRA and DSA as gold standard. • High resolution MRA at 3 T for the depiction of small pedal vessels. • Evaluation of high resolution non-enhanced MRA in PAOD patients.

  6. Nonenhanced peripheral MR-angiography (MRA) at 3 Tesla: evaluation of quiescent-interval single-shot MRA in patients undergoing digital subtraction angiography.

    PubMed

    Wagner, Moritz; Knobloch, Gesine; Gielen, Martin; Lauff, Marie-Teres; Romano, Valentina; Hamm, Bernd; Kröncke, Thomas

    2015-04-01

    Quiescent-interval single-shot MRA (QISS-MRA) is a promising nonenhanced imaging technique for assessment of peripheral arterial disease (PAD). Previous studies at 3 Tesla included only very limited numbers of patients for correlation of QISS-MRA with digital subtraction angiography (DSA) as standard of reference (SOR). The aim of this prospective institutional review board-approved study was to compare QISS-MRA at 3 Tesla with DSA in a larger patient group. Our study included 32 consecutive patients who underwent QISS-MRA, contrast-enhanced MRA (CE-MRA), and DSA. Two readers independently performed a per-segment evaluation of QISS-MRA and CE-MRA for image quality and identification of non-significant stenosis (<50%) versus significant stenosis (50-100%). The final dataset included 1,027 vessel segments. Reader 1 and 2 rated image quality as diagnostic in 96.8 and 98.0% of the vessel segments on QISS-MRA and in 99.3 and 98.4% of the vessel segments on CE-MRA, respectively. DSA was available for 922 segments and detected significant stenosis in 133 segments (14.4%). Consensus reading yielded the following diagnostic parameters for QISS-MRA versus CE-MRA: sensitivity: 83.5% (111/133) versus 82.7% (110/133), p = 0.80; specificity: 93.9% (741/789) versus 95.7% (755/789), p = 0.25; and diagnostic accuracy: 92.4% (852/922) versus 93.8% (865/922), p = 0.35. In conclusion, using DSA as SOR, QISS-MRA and CE-MRA at 3 Tesla showed similar diagnostic accuracy in the assessment of PAD. A limitation of QISS-MRA was the lower rate of assessable vessel segments compared to CE-MRA.

  7. Value of single-dose contrast-enhanced magnetic resonance angiography versus intraarterial digital subtraction angiography in therapy indications in abdominal and iliac arteries.

    PubMed

    Schaefer, Philipp J; Schaefer, Fritz K W; Mueller-Huelsbeck, Stefan; Both, Markus; Heller, Martin; Jahnke, Thomas

    2007-01-01

    The objective of the study was to prove the value of single-dose contrast-enhanced magnetic resonance angiography [three-dimensional (3D) ceMRA] in abdominal and iliac arteries versus the reference standard intra-arterial digital subtraction angiography (i.a.DSA) when indicating a therapy. Patients suspected of having abdominal or iliac artery stenosis were included in this study. A positive vote of the local Ethics Committe was given. After written informed consent was obtained, 37 patients were enrolled, of which 34 were available for image evaluation. Both 3D ceMRA and i.a. DSA were performed for each patient. The dosage for 3D ceMRA was 0.1 mmol/kg body weight in a 1.5-T scanner with a phased-array coil. The parameters of the 3D-FLASH sequence were as follows: TR/TE 4.6/1.8 ms, effective thickness 3.5 mm, matrix 512 x 200, flip angle 30 degrees , field of view 420 mm, TA 23 s, coronal scan orientation. Totally, 476 vessel segments were evaluated for stenosis degree by two radiologists in a consensus fashion in a blinded read. For each patient, a therapy was proposed, if clinically indicated. Sensitivity, specificity, positive and negative predictive values, and accuracy for stenoses > or = 50% were 68%, 92%, 44%, 97%, and 90%, respectively. In 13/34 patients, a discrepancy was found concerning therapy decisions based on MRA findings versus therapy decisions based on the reference standard DSA. The results showed that the used MRA imaging technique of abdominal and iliac arteries is not competitive to i.a. DSA, with a high rate of misinterpretation of the MRAs resulting in incorrect therapies.

  8. Value of Single-Dose Contrast-Enhanced Magnetic Resonance Angiography Versus Intraarterial Digital Subtraction Angiography in Therapy Indications in Abdominal and Iliac Arteries

    SciTech Connect

    Schaefer, Philipp J. Schaefer, Fritz K. W.; Mueller-Huelsbeck, Stefan; Both, Markus; Heller, Martin; Jahnke, Thomas

    2007-06-15

    The objective of the study was to prove the value of single-dose contrast-enhanced magnetic resonance angiography [three-dimensional (3D) ceMRA] in abdominal and iliac arteries versus the reference standard intra-arterial digital subtraction angiography (i.a.DSA) when indicating a therapy. Patients suspected of having abdominal or iliac artery stenosis were included in this study. A positive vote of the local Ethics Committee was given. After written informed consent was obtained, 37 patients were enrolled, of which 34 were available for image evaluation. Both 3D ceMRA and i.a. DSA were performed for each patient. The dosage for 3D ceMRA was 0.1 mmol/kg body weight in a 1.5-T scanner with a phased-array coil. The parameters of the 3D-FLASH sequence were as follows: TR/TE 4.6/1.8 ms, effective thickness 3.5 mm, matrix 512 x 200, flip angle 30{sup o}, field of view 420 mm, TA 23 s, coronal scan orientation. Totally, 476 vessel segments were evaluated for stenosis degree by two radiologists in a consensus fashion in a blinded read. For each patient, a therapy was proposed, if clinically indicated. Sensitivity, specificity, positive and negative predictive values, and accuracy for stenoses {>=}50% were 68%, 92%, 44%, 97%, and 90%, respectively. In 13/34 patients, a discrepancy was found concerning therapy decisions based on MRA findings versus therapy decisions based on the reference standard DSA. The results showed that the used MRA imaging technique of abdominal and iliac arteries is not competitive to i.a. DSA, with a high rate of misinterpretation of the MRAs resulting in incorrect therapies.

  9. Comparison of extracranial artery stenosis and cerebral blood flow, assessed by quantitative magnetic resonance, using digital subtraction angiography as the reference standard

    PubMed Central

    Cai, Jingjing; Wu, Dan; Mo, Yongqian; Wang, Anxin; Hu, Shiyu; Ren, Lijie

    2016-01-01

    Abstract Extracranial arteriosclerosis usually indicates a high risk of ischemic stroke. In the past, a clinical decision following diagnosis was dependent on the percentage of vessel stenosis determined by an invasive technique. We aimed to develop a quantitative magnetic resonance (QMR) technique to evaluate artery structure and cerebral hemodynamics noninvasively. QMR and digital subtraction angiography (DSA) were performed in 67 patients with suspected cerebral vascular disease at our hospital. Accuracy, sensitivity, positive predictive values (PPVs), negative predictive values (NPVs), and Pearson correlation coefficient of QMR were calculated and compared for the detection and measurement of vascular stenoses using DSA as a gold standard. For patients with unilateral artery stenosis, quantitative cerebral blood flow (CBF) was measured by QMR in ipsilateral and contralateral hemispheres. Among 67 subjects (male 54, female 12), 201 stenoses were detected by QMR and DSA. QMR measuring the degree of stenosis and lesion length was in good correlation with the results obtained by DSA (r2 = 0.845, 0.721, respectively). As for artery stenosis, PPV and NPV of QMR were 89.55% and 95.71%, respectively. As for severe stenosis, sensitivity and specificity of QMR were 82.3% and 86.0% with DSA as a reference. For subjects with unilateral carotid stenosis, CBF in basal ganglia decreased significantly (P < 0.001) compared with the contralateral one in symptomatic and asymptomatic groups. For subjects with moderate stenosis (50–79%), CBF of temporal and basal ganglia was decreased compared with the contralateral ganglia. However, CBF in subjects with severe stenosis or occlusion in the basal ganglia was mildly elevated compared with the contralateral ganglia (P < 0.001). In our study, a good correlation was found between QMR and DSA when measuring artery stenosis and CBF. QMR may become an important method for measuring artery stenosis and cerebral hemodynamics in

  10. Implication of cerebral circulation time in intracranial stenosis measured by digital subtraction angiography on cerebral blood flow estimation measured by arterial spin labeling

    PubMed Central

    Jann, Kay; Hauf, Martinus; Kellner-Weldon, Frauke; El-Koussy, Marwan; Kiefer, Claus; Federspiel, Andrea; Schroth, Gerhard

    2016-01-01

    PURPOSE Arterial spin labeling (ASL) magnetic resonance imaging to assess cerebral blood flow (CBF) is of increasing interest in basic research and in diagnostic applications, since ASL provides similar information to positron emission tomography about perfusion in vascular territories. However, in patients with steno-occlusive arterial disease (SOAD), CBF as measured by ASL might be underestimated due to delayed bolus arrival, and thus increased spin relaxation. We aimed to estimate the extent to which bolus arrival time (BAT) was delayed in patients with SOAD and whether this resulted in underestimation of CBF. METHODS BAT was measured using digital subtraction angiography (DSA) in ten patients with high-grade stenosis of the middle carotid artery (MCA). Regional CBF was assessed with pseudocontinuous ASL. RESULTS BATs were nonsignificantly prolonged in the stenotic hemisphere 4.1±2.0 s compared with the healthy hemisphere 3.3±0.9 s; however, there were substantial individual differences on the stenotic side. CBF in the anterior and posterior MCA territories were significantly reduced on the stenotic hemisphere. Severe stenosis was correlated with longer BAT and lower quantified CBF. CONCLUSION ASL-based perfusion measurement involves a race between the decay of the spins and the delivery of labeled blood to the region of interest. Special caution is needed when interpreting CBF values quantified in individuals with altered blood flow and delayed circulation times. However, from a clinician’s point of view, an accentuation of hypoperfusion (even if caused by underestimation of CBF due to prolonged BATs) might be desirable since it indexes potentially harmful physiologic deficits. PMID:27411297

  11. Evaluation of a noise reduction imaging technology in iliac digital subtraction angiography: noninferior clinical image quality with lower patient and scatter dose.

    PubMed

    van Strijen, Marco J; Grünhagen, Thijs; Mauti, Maria; Zähringer, Markus; Gaines, Peter A; Robinson, Graham J; Railton, Nicholas J; van Overhagen, Hans; Habraken, Jan; van Leersum, Marc

    2015-05-01

    To determine whether equivalent-quality images can be obtained from digital subtraction angiography (DSA) of the iliac artery after implementation of a novel imaging technology that reduces patient and scatter x-ray dose. Imaging using two randomly ordered DSA runs was performed in 51 adults scheduled for iliac artery angiography or intervention or both. One DSA run used standard acquisition chain and image processing algorithms (referred to as " reference DSA"), and the other DSA run used dose-reduction and real-time advanced image noise reduction technology (referred to as "study DSA"). The quality of each pair of runs, consecutively performed without changes in working projection or injection parameters, was independently rated by five radiologists blinded to the imaging technology used. Patient radiation dose was evaluated using air kerma and dose area product, and scatter dose was evaluated using three dosimeters (DoseAware, Philips Healthcare, Best, The Netherlands), located at fixed positions. Comparable image pairs were available in 48 patients. There were 44 patients undergoing treatment involving the common (n = 33) or external (n = 29) iliac arteries. Study DSA images were rated as equal to or better than reference DSA images for 96% of comparisons, with an average overall agreement among raters of 0.93 (95% confidence interval, 0.65-0.96). Mean patient radiation dose (n = 48) and scatter dose rate for the three dosimeters (n = 50) was 83% ± 5 and 69% ± 10 lower, respectively, using the study technology (P < .001). Iliac artery DSA performed using a dose-reduction and real-time advanced image noise reduction technology results in image quality that is noninferior to conventional DSA but with significantly lower patient and scatter radiation exposure (P < .001). Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.

  12. [Digital subtract arteriographic characteristics of carotid artery, vertebral artery, subclavian artery and renal artery in type 2 diabetic patients with lower extremities peripheral arterial disease].

    PubMed

    Chen, Da-Wei; Lu, Wu-Sheng; Wang, Chun; Jiao, He; Tian, Hao-Ming; Ran, Xing-Wu

    2012-09-01

    To investigate angiographical characteristics of carotid, vertebral, subclavian, and renal arteries in the type 2 diabetic patients with lower extremities peripheral arterial disease (LEPAD). There were 104 type 2 diabetic patients with LEPAD recruited in this study, who received digital subtract arteriography (DSA). Ankle-brachial index (ABI) assessment was also performed in 50 participants. Dependent upon the stenosis degree of vertebral artery, subclavian artery and renal artery measured by DSA, the patients were divided into normal group (stenosis < or = 50%) or pathological group(stenosis > 50% or blocked lesions). The angiographic features of carotid, vertebral, subclavian, and renal arteries were analyzed and the relationship between arterial stenosis and ABI was explored. DSA results of 104 patients showed that the most common lesion in the arteries was plaque. The stenosis degrees of 51%-74% and 75%-99% were most commonly observed in renal artery, with incidence of 22.1% and 5.8%, respectively. Arterial occlusion was most commonly observed in vertebral artery, with incidence of 27.9%. The patients with stenosis or occlusion of arteries had lower ABI (P = 0.000), and the patients with stenosis or occlusion of vertebral and renal arteries also had lower ABI (P = 0.003 and 0.02, respectively), compared with those without stenosis. ABI < 0.9 indicated higher risk of stenosis or occlusion of vertebral and renal arteries (P = 0.008 and 0.047 respectively). Between the patients with subclavian arterial stenosis and those without this artery stenosis, there was no statistical significant difference observed in ABI level. Type 2 diabetic patients with LEPAD can affect multiple arteries, showing plaque formation, multi-segmental stenosis and occlusion of arteries. The patients with ABI < 0.9 have higher risk of multiple arterial stenosis or occlusion lesions.

  13. Determination of cardiac ejection fraction and left ventricular volume: contrast-enhanced ultrafast cine MR imaging vs IV digital subtraction ventriculography.

    PubMed

    Matsumura, K; Nakase, E; Haiyama, T; Takeo, K; Shimizu, K; Yamasaki, K; Kohno, K

    1993-05-01

    To assess the accuracy of contrast-enhanced, single breath-hold cine MR imaging in the calculation of left ventricular volume and ejection fraction, we compared values obtained by using this method with those obtained by using IV digital subtraction angiography (IV-DSA). All patients (n = 28) had conventional cine and contrast-enhanced ultrafast cine MR imaging. For ultrafast cine MR imaging, a phase-rewind gradient-echo (rewind-SMASH) sequence was used: TR, 8 msec (standard excitation and acquisition block of 6 msec with phase rewind pulse of 2 msec); TE, 3.2 msec; a 128 x 96 matrix (pile encode factor, 6; k-space segment, 16); a 200-mm field of view; and one excitation. Values for left ventricular volume and ejection fraction obtained with ultrafast cine MR imaging correlated well with those obtained with IV-DSA (end-diastolic volume, y = 0.986x - 7.79, r = .985; end-systolic volume, y = 0.863x + 0.71, r = .984; ejection fraction, y = 0.877x + 6.44, r = .887). In the calculation of left ventricular volume by the area-length method, manual tracing of the left ventricular cavity was more difficult when the conventional cine method was used than when the enhanced ultrafast cine method was used. Our results show that cardiac multiphase study with horizontal long-axis, first-pass, contrast-enhanced, single breath-hold, cine MR imaging is an accurate and highly reproducible method of evaluating left ventricular volume and ejection fraction.

  14. Accuracy of Voxel-Based and Algebraic Formula-Based Methods in Quantifying Cerebral Aneurysm Volume by 3D-Rotational Digital Subtraction Angiography

    PubMed Central

    Fanning, N.F.; O'dwyer, H.M.; Bowden, J.A.B.; Brennan, P.R.; Thornton, J.

    2005-01-01

    Summary Accurate knowledge of cerebral aneurysm volume would be valuable in guiding the volume of embolized material required for optimal filling of an aneurysm sac and recording percentage volume filling. Algebraic volumes are frequently estimated by algebraic volume formulae. 3D digital subtraction angiography (DSA) aids endovascular treatment planning and yields volumetric data. Our aim was to define the accuracy of 3D-DSA in quantifying aneurysm volume using an automated voxel-based volumetric method (voxel volume method) and compare results to volumes calculated by ellipsoid and cylindrical algebraic formulae (algebraic volume method). We constructed 13 latex aneurysm moulds and measured their true volumes using a micro-pipette in-vitro. 3D-DSA was performed on contrast filled moulds and experimental volume estimated by both voxel and algebraic methods. In our in-vivo study we quantified the voxel and algebraic volumes from the 3D data sets of 75 cerebral aneurysms. The linear regression test provided correction values between voxel and algebraic methods. The in-vitro study showed that the voxel volume method was the most accurate (mean percentage deviation from true volume 3.7 ±3.5%; p = 0.9). The ellipsoid method significantly underestimated -11.2 ±13.6%; p<0.05) and the cylindrical method overestimated (42.6±35.7%; p<0.05) true aneurysm volume. Similar results were obtained in-vivo. While algebraic measurements could be corrected by an equation, the clinical usefulness of this equation is questionable due to the large volume range to achieve a 95% confidence interval. The voxel volume method is accurate in quantifying aneurysm volume. Aneurysms in-vivo do not conform to simple algebraic geometry. Aneurysm volume on 3D-DSA should be calculated by the voxel-based method and not by algebraic formulae. PMID:20584433

  15. Gadofosveset-enhanced MR angiography of carotid arteries: does steady-state imaging improve accuracy of first-pass imaging? Comparison with selective digital subtraction angiography.

    PubMed

    Anzidei, Michele; Napoli, Alessandro; Marincola, Beatrice Cavallo; Nofroni, Italo; Geiger, Daniel; Zaccagna, Fulvio; Catalano, Carlo; Passariello, Roberto

    2009-05-01

    To evaluate the diagnostic accuracy of gadofosveset-enhanced magnetic resonance (MR) angiography in the assessment of carotid artery stenosis, with digital subtraction angiography (DSA) as the reference standard, and to determine the value of reading first-pass, steady-state, and "combined" (first-pass plus steady-state) MR angiograms. This study was approved by the local ethics committee, and all subjects gave written informed consent. MR angiography and DSA were performed in 84 patients (56 men, 28 women; age range, 61-76 years) with carotid artery stenosis at Doppler ultrasonography. Three readers reviewed the first-pass, steady-state, and combined MR data sets, and one independent observer evaluated the DSA images to assess stenosis degree, plaque morphology and ulceration, stenosis length, and tandem lesions. Interobserver agreement regarding MR angiographic findings was analyzed by using intraclass correlation and Cohen kappa coefficients. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated by using the McNemar test to determine possible significant differences (P < .05). Interobserver agreement regarding all MR angiogram readings was substantial. For grading stenosis, sensitivity, specificity, PPV, and NPV were, respectively, 90%, 92%, 91%, and 91% for first-pass imaging; 95% each for steady-state imaging; and 96%, 99%, 99%, and 97% for combined imaging. For evaluation of plaque morphology, respective values were 84%, 86%, 88%, and 82% for first-pass imaging; 98%, 97%, 98%, and 97% for steady-state imaging; and 98%, 100%, 100%, and 97% for combined imaging. Differences between the first-pass, steady-state, and combined image readings for assessment of stenosis degree and plaque morphology were significant (P < .001). Gadofosveset-enhanced MR angiography is a promising technique for imaging carotid artery stenosis. Steady-state image reading is superior to first-pass image reading, but the combined

  16. Radiation dose incurred in the exclusion of vascular filling in transforaminal epidural steroid injections: fluoroscopy, digital subtraction angiography, and CT/fluoroscopy.

    PubMed

    Maus, Timothy; Schueler, Beth A; Leng, Shuai; Magnuson, Dayne; Magnuson, Dixon J; Diehn, Felix E

    2014-08-01

    This study seeks to measure the radiation dose incurred in the evaluation of vascular filling during transforaminal epidural steroid injections (TFESI) using conventional fluoroscopy (CF), digital subtraction angiography (DSA), and multislice, pulsed computed tomography fluoroscopy (CT/F). Three portable C-arms and a fixed multipurpose C-arm were evaluated. The radiation dose rate was measured using an anthropomorphic phantom during CF and DSA in anterior-posterior positions for cervical and lumbar TFESIs. Effective doses were calculated for 5-second exposures. The effective doses incurred in the cervical and lumbar spine during two CT/F exposures were calculated based on the reported volume CT dose index and dose length product. DSA imaging increased the effective dose incurred over CF with portable C-arms (medium dose rate) by 2.5-4.3 fold for cervical TFESI and 2.3-4.2 fold for lumbar TFESI. The incremental dose incurred with DSA ranged from 4.0 to 7.7 μSv in the cervical region and from 22-38 μSv in the lumbar spine. CT/F increased the incurred dose 19-fold in the cervical region and 8.0-fold in the lumbar region (incremental doses 49 μSv and 140 μSv, respectively) relative to CF. The use of DSA imaging to exclude vascular uptake during TFESI increases radiation dose over CF. CT/F incurs additional dose beyond most DSA. Minimizing radiation dose by limiting DSA and CT/F use to spine segments or clinical situations involving higher risk may be desirable. However, the incremental radiation doses incurred by DSA or CT/F are of such low magnitude that health risks cannot currently be estimated. Wiley Periodicals, Inc.

  17. Structural and functional changes relevant to maxillary arterial flow observed during computed tomography and nonselective digital subtraction angiography in cats with the mouth closed and opened.

    PubMed

    Scrivani, Peter V; Martin-Flores, Manuel; van Hatten, Ruth; Bezuidenhout, Abraham J

    2014-01-01

    Some cats develop blindness during procedures with mouth gags, which possibly relates to maxillary arterial occlusion by opening the mouth. Our first aim was to use computed tomography (CT) to describe how vascular compression is possible based on morphologic differences between mouth positions. Our second aim was to use nonselective digital subtraction angiography to assess whether opening the mouth induces collateral circulation. Six healthy cats were examined. During CT, the maxillary artery coursed between the angular process of the mandible and the rostrolateral wall of the tympanic bulla. The median distance between these structures was shorter when the mouth was opened (left, 4.3 mm; right, 3.6 mm) vs. closed (left, 6.9 mm; right, 7.1 mm). Additionally, the distance was shorter on the side ipsilateral to the gag (P = 0.03). During nonselective angiography, with the mouth closed, there was strong sequential opacification of the external carotid arteries, maxillary arteries, maxillary retia mirabilia, cerebral arterial circle, and basilar artery. Additionally, there was uniform opacification of the cerebrum and cerebellum. With the mouth opened, opacification of the maxillary arteries (rostral to the angular processes) was reduced in all cats, the cerebral arterial circle and basilar artery had simultaneous opacification in four of six (67%) cats, and the cerebrum had reduced opacification compared to the cerebellum in four of six (67%). In conclusion, the maxillary arteries are situated such that they can be compressed when opening the mouth. Opening the mouth did not consistently induce collateral circulation sufficient to produce comparable cerebral opacification as when the mouth was closed. © 2013 American College of Veterinary Radiology.

  18. CT perfusion with angiography as a substitute for both conventional digital subtraction angiography and acetazolamide-challenged SPECT in the follow-up of postbypass patients.

    PubMed

    Park, Jung Cheol; Kim, Jeong Eun; Kang, Hyun-Seung; Sohn, Chul-Ho; Lee, Dong Soo; Oh, Chang Wan; Han, Moon Hee

    2010-01-01

    We evaluated the clinical usefulness of CT perfusion (CTP) with angiography (CTA) as an alternative to digital subtraction angiography (DSA) and acetazolamide (ACZ)-challenged single-photon emission computed tomography (SPECT) in the follow-up evaluation of hemodynamic changes and bypass patency after bypass surgery in chronic cerebral ischemic diseases. Thirty-five patients who underwent superficial temporal artery/middle cerebral artery bypass surgery for chronic cerebral ischemic diseases were retrospectively enrolled. We assessed the relationship between CTP parameters [cerebral blood volume, cerebral blood flow (CBF), mean transit time (MTT), affected-to-unaffected hemisphere (ATU) ratio of perfusion parameters and MTT differences between hemispheres] and SPECT parameters (regional CBF and cerebrovascular reserve) and compared the preoperative CTP parameters with the postoperative ones. For the bypass patency, we compared CTA with DSA. MTT showed the best correlation with CVR of SPECT (r = -0.343; p < 0.001). ATU ratio (r = -0.547; p < 0.001) and ATU differences (r = -0.592; p < 0.001) of MTT correlated well with the ATU ratio of rCBF on ACZ-challenged SPECT. Significant improvement of perfusion parameters could be demonstrated in the affected vascular territory with postoperative CTP. The CTA findings were consistent with those of DSA in 96% of the cases. The examination-related complication rate was 0, 2.8 and 8.6% for CT studies, DSA and SPECT, respectively. CTP performed simultaneously with CTA seems to be a safe and efficient substitute for DSA and ACZ-challenged SPECT in the follow-up evaluation after bypass surgery in patients with chronic cerebral ischemic diseases. Copyright © 2010 S. Karger AG, Basel.

  19. Internal carotid artery stenosis: accuracy of subjective visual impression for evaluation with digital subtraction angiography and contrast-enhanced MR angiography.

    PubMed

    U-King-Im, Jean Marie; Graves, Martin J; Cross, Justin J; Higgins, Nicholas J; Wat, Josephine; Trivedi, Rikin A; Tang, Tjun; Howarth, Simon P S; Kirkpatrick, Peter J; Antoun, Nagui M; Gillard, Jonathan H

    2007-07-01

    To prospectively determine, for both digital subtraction angiography (DSA) and contrast material-enhanced magnetic resonance (MR) angiography, the accuracy of subjective visual impression (SVI) in the evaluation of internal carotid artery (ICA) stenosis, with objective caliper measurements serving as the reference standard. Local ethics committee approval and written informed patient consent were obtained. A total of 142 symptomatic patients (41 women, 101 men; mean age, 70 years; age range, 44-89 years) suspected of having ICA stenosis on the basis of Doppler ultrasonographic findings underwent both DSA and contrast-enhanced MR angiography. With each modality, three independent neuroradiologists who were blinded to other test results first visually estimated and subsequently objectively measured stenoses. Diagnostic accuracy and percentage misclassification for correct categorization of 70%-99% stenosis were calculated for SVI, with objective measurements serving as the reference standard. Interobserver variability was determined with kappa statistics. After exclusion of arteries that were unsuitable for measurement, 180 vessels remained for analysis with DSA and 159 vessels remained for analysis with contrast-enhanced MR angiography. With respect to 70%-99% stenosis, SVI was associated with average misclassification of 8.9% for DSA (8.9%, 7.8%, and 10.0% for readers A, B, and C, respectively) and of 11.7% for contrast-enhanced MR angiography (11.3%, 8.8%, and 15.1% for readers A, B, and C, respectively). Negative predictive values were excellent (92.3%-100%). Interobserver variability was higher for SVI (DSA, kappa = 0.62-0.71; contrast-enhanced MR angiography, kappa = 0.57-0.69) than for objective measurements (DSA, kappa = 0.75-0.80; contrast-enhanced MR angiography, kappa = 0.66-0.72). SVI alone is not recommended for evaluation of ICA stenosis with both DSA and contrast-enhanced MR angiography. SVI may be acceptable as an initial screening tool to exclude the

  20. Accuracy of end-tidal CO2 measurement through the nose and pharynx in nonintubated patients during digital subtraction cerebral angiography.

    PubMed

    Zhang, Chunyan; Wang, Maohua; Wang, Rurong; Wang, Wenjian

    2013-04-01

    To determine the accuracy of end-tidal CO2 (PETCO2) obtained in the nose through the Smart CapnoLine and in the pharynx through the modified Filterline H Set with supplemental oxygen at 5 L/min in nonintubated patients undergoing digital subtraction cerebral angiography (DSA). Prospective, observational. Twenty patients with disturbance of consciousness because of brain disease, who will receive DSA. PETCO2 was measured in the nose through the Smart CapnoLine and in the pharynx using the modified Filterline H Set that was inserted through the nasopharyngeal airway. Oxygen was administered through the Smart CapnoLine at a rate of 5 L/min. Five minutes after a constant and normally shaped capnography waveform, arterial blood was drawn from an indwelling femoral catheter for analyzing arterial CO2 partial pressure (PaCO2), and PETCO2 that was measured through the nose and the pharynx were simultaneously recorded. After the DSA procedure, PaCO2 was analyzed again. Data were analyzed with Pearson correlation and Bland-Altman analysis. PETCO2 sampled from both the nose and the pharynx was significantly correlated with PaCO2, and the correlation coefficients had approximate values, 0.832 (P<0.0001) for PaCO2 with PETCO2 through the nose and 0.836 (P<0.0001) for PaCO2 with PETCO2 through the pharynx. The mean bias±SD for PETCO2 and PaCO2 was 4.53±2.76 mm Hg (nose) and 3.22±2.86 mm Hg (pharynx). The 95% level of agreement for PETCO2 and PaCO2 ranged from -0.90 to 9.95 mm Hg (nose) and from -2.39 to 8.82 mm Hg (pharynx). End-tidal CO2 measurements through the nose and the pharynx had comparable performance. The correlation of PETCO2 measured through the nose and the pharynx was 0.971 (P<0.001). The difference between PETCO2 measured through the nose and the pharynx was 1.31±1.25 mm Hg, and t test results showed that arterial to end-tidal CO2 pressure difference (Pa-ETCO2) in sampling through the nose was significantly greater than Pa-ETCO2 sampling through the pharynx (P

  1. Detection of carotid artery stenosis using histological specimens: a comparison of CT angiography, magnetic resonance angiography, digital subtraction angiography and Doppler ultrasonography.

    PubMed

    Netuka, David; Belšán, Tomáš; Broulíková, Karolina; Mandys, Václav; Charvát, František; Malík, Josef; Coufalová, Lucie; Bradáč, Ondřej; Ostrý, Svatopluk; Beneš, Vladimír

    2016-08-01

    Carotid endarterectomy (CEA) is accepted as a primary modality to treat carotid stenosis. The accuracy of measuring carotid stenosis is important for indication of the CEA procedure. Different diagnostic tools have been developed and used in the past 2 decades for the diagnosis of carotid stenosis. Only a few studies, however, have focused on the comparison of different diagnostic tools to histological findings of carotid plaque. Patients with internal carotid artery (ICA) stenosis were investigated primarily by computed tomography angiography (CTA). Digital subtraction angiography (DSA), Doppler ultrasonography (DUS) and magnetic resonance angiography (MRA) were performed as well. Atherosclerotic plaque specimens were transversally cut into smaller segments and histologically processed. The slides were scanned and specimens showing maximal stenosis were determined; the minimal diameter and the diameter of the whole plaque were measured. High quality histological specimen and histological measurement was considered to be the prerequisite for inclusion into the analysis. The preoperative findings were compared with histological measurement. CTA and histological measurements were obtained from 152 patients. DSA measurements were available in 138 of these cases, MRA in 107 and DUS in 88. A comparison between preoperative and histological findings was performed. In addition, correlation coefficients were computed and tested. A significant correlation was found for each of the diagnostic procedures. The strongest correlation coefficient and the best allocation of stenosis into clinical significant groups (<50 %, 50-69 %, ≥70 %) was observed for CTA. Mean differences in the whole cohort between preoperative and histological measurements were as follows: CTA underestimated histological measurement by 2.4 % (based on European Carotid Surgery Trial [ECST] methodology) and 11.9 % (based on North American Symptomatic Carotid Endarterectomy Trial [NASCET] methodology

  2. Diagnostic yield and accuracy of CT angiography, MR angiography, and digital subtraction angiography for detection of macrovascular causes of intracerebral haemorrhage: prospective, multicentre cohort study

    PubMed Central

    Velthuis, Birgitta K; Rinkel, Gabriël J E; Algra, Ale; de Kort, Gérard A P; Witkamp, Theo D; de Ridder, Johanna C M; van Nieuwenhuizen, Koen M; de Leeuw, Frank-Erik; Schonewille, Wouter J; de Kort, Paul L M; Dippel, Diederik W; Raaymakers, Theodora W M; Hofmeijer, Jeannette; Wermer, Marieke J H; Kerkhoff, Henk; Jellema, Korné; Bronner, Irene M; Remmers, Michel J M; Bienfait, Henri Paul; Witjes, Ron J G M; Greving, Jacoba P; Klijn, Catharina J M

    2015-01-01

    Study question What are the diagnostic yield and accuracy of early computed tomography (CT) angiography followed by magnetic resonance imaging/angiography (MRI/MRA) and digital subtraction angiography (DSA) in patients with non-traumatic intracerebral haemorrhage? Methods This prospective diagnostic study enrolled 298 adults (18-70 years) treated in 22 hospitals in the Netherlands over six years. CT angiography was performed within seven days of haemorrhage. If the result was negative, MRI/MRA was performed four to eight weeks later. DSA was performed when the CT angiography or MRI/MRA results were inconclusive or negative. The main outcome was a macrovascular cause, including arteriovenous malformation, aneurysm, dural arteriovenous fistula, and cavernoma. Three blinded neuroradiologists independently evaluated the images for macrovascular causes of haemorrhage. The reference standard was the best available evidence from all findings during one year’s follow-up. Study answer and limitations A macrovascular cause was identified in 69 patients (23%). 291 patients (98%) underwent CT angiography; 214 with a negative result underwent additional MRI/MRA and 97 with a negative result for both CT angiography and MRI/MRA underwent DSA. Early CT angiography detected 51 macrovascular causes (yield 17%, 95% confidence interval 13% to 22%). CT angiography with MRI/MRA identified two additional macrovascular causes (18%, 14% to 23%) and these modalities combined with DSA another 15 (23%, 18% to 28%). This last extensive strategy failed to detect a cavernoma, which was identified on MRI during follow-up (reference strategy). The positive predictive value of CT angiography was 72% (60% to 82%), of additional MRI/MRA was 35% (14% to 62%), and of additional DSA was 100% (75% to 100%). None of the patients experienced complications with CT angiography or MRI/MRA; 0.6% of patients who underwent DSA experienced permanent sequelae. Not all patients with negative CT angiography and

  3. Animal experiments by K-edge subtraction angiography by using SR (abstract)

    NASA Astrophysics Data System (ADS)

    Anno, I.; Akisada, M.; Takeda, T.; Sugishita, Y.; Kakihana, M.; Ohtsuka, S.; Nishimura, K.; Hasegawa, S.; Takenaka, E.; Hyodo, K.; Ando, M.

    1989-07-01

    Ischemic heart disease is one of the most popular and lethal diseases for aged peoples in the world, and is usually diagnosed by transarterial selective coronary arteriography. However, it is rather invasive and somewhat dangerous, so that the selective coronary arteriography is not feasible for prospective screening of coronary occlusive heart disease. Conventional digital subtraction angiography (DSA) is widely known as a relatively noninvasive and useful technique is making a diagnosis of arterial occlusive disease, especially in making the diagnosis of ischemic heart disease. Conventional intravenous subtraction angiography by temporal subtraction, however, has several problems when applying to the moving objects. Digital subtraction method using high-speed switching above and below the K edge could be the ideal approach to this solution. We intend to make a synchrotron radiation digital K-edge subtraction angiography in the above policy, and to apply it to the human coronary ischemic disease on an outpatient basis. The principles and experimental systems have already been described in detail by our coworkers. Our prototype experimental system is situated at the AR (accumulation ring) for TRISTAN project of high energy physics. The available beam size is 70 mm by 120 mm. The electron energy of AR is 6.5 GeV and average beam current is approximately 10 mA. This paper will show the animal experiments of our K-edge subtraction system, and discuss some problems and technical difficulties. Three dogs, weighing approximately 15 kg, were examined to evaluate the ability of our prototype synchrotron radiation DSA unit, that we are now constructing. The dogs were anaesthetized with pentobarbital sodium, intravenously (30 mg/kg). Six french-sized (1.52 mm i.d.) pigtail catheter with multiple side holes were introduced via the right femoral vein into the right atrium by the cutdown technique under conventional x-ray fluoroscopic control. Respiration of the dogs was

  4. Strategies in Subtraction Problem Solving in Children

    ERIC Educational Resources Information Center

    Barrouillet, Pierre; Mignon, Mathilde; Thevenot, Catherine

    2008-01-01

    The aim of this study was to investigate the strategies used by third graders in solving the 81 elementary subtractions that are the inverses of the one-digit additions with addends from 1 to 9 recently studied by Barrouillet and Lepine. Although the pattern of relationship between individual differences in working memory, on the one hand, and…

  5. Quantitative analysis of synchrotron radiation intravenous angiographic images

    NASA Astrophysics Data System (ADS)

    Sarnelli, Anna; Nemoz, Christian; Elleaume, Hélène; Estève, François; Bertrand, Bernard; Bravin, Alberto

    2005-02-01

    A medical research protocol on clinical intravenous coronary angiography has been completed at the European Synchrotron Radiation Facility (ESRF) biomedical beamline. The aim was to investigate the accuracy of intravenous coronary angiography based on the K-edge digital subtraction technique for the detection of in-stent restenosis. For each patient, diagnosis has been performed on the synchrotron radiation images and monitored with the conventional selective coronary angiography method taken as the golden standard. In this paper, the methods of image processing and the results of the quantitative analysis are described. Image processing includes beam harmonic contamination correction, spatial deconvolution and the extraction of a 'contrast' and a 'tissue' image from each couple of radiograms simultaneously acquired at energies bracketing the K-edge of iodine. Quantitative analysis includes the estimation of the vessel diameter, the calculation of the absolute iodine concentration profiles along the coronary arteries and the stenosis degree measurement.

  6. Added Value of Bone Subtraction in Dual-energy Digital Radiography in the Detection of Pneumothorax: Impact of Reader Expertise and Medical Specialty.

    PubMed

    Urbaneja, Ayla; Dodin, Gauthier; Hossu, Gabriela; Bakour, Omar; Kechidi, Rachid; Gondim Teixeira, Pedro; Blum, Alain

    2017-08-08

    This study aimed to determine the value of dual-energy thoracic radiography in the diagnosis of pneumothorax considering the reader's experience. Forty patients with a suspected pneumothorax, imaged with dual-energy chest radiographs, were divided into two groups: those with pneumothorax as the final diagnosis (n = 19) and those without (n = 21). The images were analyzed by 36 readers (5 interns, 16 residents, 15 senior physicians) for the presence or absence of pneumothorax during three readout sessions at 2-week intervals: standard images alone (session 1), dual-energy images with bone subtraction alone (session 2), and a combination of the two (session 3). The number of correct responses increased 13.3% between sessions 1 and 2 (P < .001) and 9.4% between sessions 1 and 3 (P < .001). The mean sensitivity for pneumothorax detection was higher in sessions 2 (82%) and 3 (79%) compared to session 1 (70%). There was no statistically significant difference in specificity between the sessions. The number of correct responses for small volume pneumothoraces was higher in sessions 2 (10.6 ± 1.8) and 3 (10.1 ± 2.0) than in session 1 (8.9 ± 2.3), with a statistically significant difference between sessions 1 and 2 (P = .002) and between sessions 1 and 3 (P = .048). Bone subtracted dual-energy thoracic radiographs improve the detection sensitivity of pneumothorax, including in cases of small pneumothoraces, regardless of the reader's level or expertise. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  7. SR high-speed K-edge subtraction angiography in the small animal (abstract)

    NASA Astrophysics Data System (ADS)

    Takeda, T.; Akisada, M.; Nakajima, T.; Anno, I.; Ueda, K.; Umetani, K.; Yamaguchi, C.

    1989-07-01

    To assess the ability of the high-speed K-edge energy subtraction system which was made at beamline 8C of Photon Factory, Tsukuba, we performed an animal experiment. Rabbits were used for the intravenous K-edge subtraction angiography. In this paper, the actual images of the artery obtained by this system, are demonstrated. The high-speed K-edge subtraction system consisted of movable silicon (111) monocrystals, II-ITV, and digital memory system. Image processing was performed by 68000-IP computer. The monochromatic x-ray beam size was 50×60 mm. Photon energy above and below iodine K edge was changed within 16 ms and 32 frames of images were obtained sequentially. The rabbits were anaesthetized by phenobarbital and a 5F catheter was inserted into inferior vena cava via the femoral vein. 1.5 ml/kg of contrast material (Conlaxin H) was injected at the rate of 0.5 ml/kg/s. TV images were obtained 3 s after the starting point of injection. By using this system, the clear K-edge subtracted images were obtained sequentially as a conventional DSA system. The quality of the images were better than that obtained by DSA. The dynamical blood flow was analyzed, and the best arterial image could be selected from the sequential images. The structures of aortic arch, common carotid arteries, right subclavian artery, and internal thoracic artery were obtained at the chest. Both common carotid arteries and vertebral arteries were recorded at the neck. The diameter of about 0.3-0.4 mm artery could be clearly revealed. The high-speed K-edge subtraction system demonstrates the very sharp arterial images clearly and dynamically.

  8. Sky subtraction for LAMOST

    NASA Astrophysics Data System (ADS)

    Bai, Zhong-Rui; Zhang, Hao-Tong; Yuan, Hai-Long; Li, Guang-Wei; Chen, Jian-Jun; Lei, Ya-Juan; Yang, Hui-Qin; Dong, Yi-Qiao; Wang, Gang; Zhao, Yong-Heng

    2017-09-01

    Sky subtraction is a key technique in data reduction of multi-fiber spectra. Knowledge of characteristics related to the instrument is necessary to determine the method adopted in sky subtraction. In this study, we describe the sky subtraction method designed for the Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) survey. The method has been integrated into the LAMOST 2D Pipeline v2.6 and applied to data from LAMOST DR3 and later. For LAMOST, calibration using sky emission lines is used to alleviate the position-dependent (and thus time-dependent) ∼ 4 % fiber throughput uncertainty and small wavelength instability (0.1 Å) during observation. Sky subtraction using principal component analysis (PCA) further reduces 25% of the sky line residual from OH lines in the red part of LAMOST spectra after the master sky spectrum, which is derived from a B-spline fit of 20 sky fibers in each spectrograph. Using this approach, values are adjusted by a sky emission line and subtracted from each fiber. Further analysis shows that our wavelength calibration accuracy is about 4.5 km s‑1, and the averages of residuals after sky subtraction are about 3% for sky emission lines and 3% for the continuum region. The relative sky subtraction residuals vary with moonlight background brightness, and can reach as low as 1.5% for regions that have sky emission lines during a dark night. Tests on F stars with both similar sky emission line strength and similar object continuum intensity show that the sky emission line residual of LAMOST is smaller than that of the SDSS survey.

  9. Effect of x-ray energy dispersion in digital subtraction imaging at the iodine K-edge--A Monte Carlo study

    SciTech Connect

    Prino, F.; Ceballos, C.; Cabal, A.; Sarnelli, A.; Gambaccini, M.; Ramello, L.

    2008-01-15

    The effect of the energy dispersion of a quasi-monochromatic x-ray beam on the performance of a dual-energy x-ray imaging system is studied by means of Monte Carlo simulations using MCNPX (Monte Carlo N-Particle eXtended) version 2.6.0. In particular, the case of subtraction imaging at the iodine K-edge, suitable for angiographic imaging application, is investigated. The average energies of the two beams bracketing the iodine K-edge are set to the values of 31.2 and 35.6 keV corresponding to the ones obtained with a compact source based on a conventional x-ray tube and a mosaic crystal monochromator. The energy dispersion of the two beams is varied between 0 and 10 keV of full width at half-maximum (FWHM). The signal and signal-to-noise ratio produced in the simulated images by iodine-filled cavities (simulating patient vessels) drilled in a PMMA phantom are studied as a function of the x-ray energy dispersion. The obtained results show that, for the considered energy separation of 4.4 keV, no dramatic deterioration of the image quality is observed with increasing x-ray energy dispersion up to a FWHM of about 2.35 keV. The case of different beam energies is also investigated by means of fast simulations of the phantom absorption.

  10. Evaluation of the hemodynamic effects of intravenous administration of ionic and nonionic contrast materials: implications for deriving physiologic measurements from computed tomography and digital cardiovascular imaging

    SciTech Connect

    Higgins, C.B.; Berber, K.H.; Mattrey, R.F.; Slutsky, R.A.

    1982-03-01

    The effects of intravenous injection of an ionic contrast material (Renografin-76 (meglumine sodium diatrizoate)) on left ventricular pressure, internal diameter, and wall thickness, and on coronary and femoral hemodynamics were compared with those of a hydrolytically stable nonionic contrast material (iohexol). Renografin-76 caused drastic biphasic changes in left ventricular pressure and dp/dt (rate of change of left ventricular pressure), and moderate changes in end systolic dimension. Iohexol caused little or no change in left ventricular pressure and dimensions. In addition, Renografin-76 caused marked arterial hypotension and large increases in coronary and femoral blood lows, while iohexol caused no significant change in arterial pressure and coronary blood flow, and a mild increase in femoral blood flow. Based on these findings, it is concluded that iohexol is preferable to standard ionic contrast material for deriving basal physiologic information from computed tomographic and digital vascular studies.

  11. Suppression subtractive hybridization.

    PubMed

    Ghorbel, Mohamed T; Murphy, David

    2011-01-01

    Comparing two RNA populations that differ from the effects of a single independent variable, such as a drug treatment or a specific genetic defect, can establish differences in the abundance of specific transcripts that vary in a population dependent manner. There are different methods for identifying differentially expressed genes. These methods include microarray, Serial Analysis of Gene Expression (SAGE), and quantitative Reverse-Transcriptase Polymerase Chain Reaction (qRT-PCR). Herein, the protocol describes an easy and cost-effective alternative that does not require prior knowledge of the transcriptomes under examination. It is specifically relevant when low levels of RNA starting material are available. This protocol describes the use of Switching Mechanism At RNA Termini Polymerase Chain Reaction (SMART-PCR) to amplify cDNA from small amounts of RNA. The amplified cDNA populations under comparison are then subjected to Suppression Subtractive Hybridization (SSH-PCR). SSH-PCR is a technique that couples subtractive hybridization with suppression PCR to selectively amplify fragments of differentially expressed genes. The resulting products are cDNA populations enriched for significantly overrepresented transcripts in either of the two input RNAs. These cDNA populations can then be cloned to generate subtracted cDNA library. Microarrays made with clones from the subtracted forward and reverse cDNA libraries are then screened for differentially expressed genes using targets generated from tester and driver total RNAs.

  12. Subtraction at NNLO

    NASA Astrophysics Data System (ADS)

    Frixione, Stefano; Grazzini, Massimiliano

    2005-06-01

    We propose a framework for the implementation of a subtraction formalism at NNLO in QCD, based on an observable- and process-independent cancellation of infrared singularities. As a first simple application, we present the calculation of the contribution to the e+e- dijet cross section proportional to CFTR.

  13. Language, visual working memory, and dot subtraction: What counts?

    PubMed

    Briere, Jennifer L; Campbell, Jamie I D

    2016-03-01

    To investigate cognitive factors affecting subtraction of visual objects, we adapted the dot subtraction task developed by Pica, Lemer, Izard, and Dehaene (2004), who used it to investigate calculation by the Mundurukú, an indigene group in Brazil that has a limited number word vocabulary. In the dot subtraction task, briefly displayed arrays of moving dots are used to represent the quantities for subtraction. We tested 40 Canadian university students' dot enumeration, Arabic digit subtraction, visual working memory, and performance on the dot subtraction task with dot display durations of 2, 1.5, 1, and .5 s. In the 2 s condition, error rates were uniformly low, whereas in the .5 s condition, error rates increased sharply as the minuend increased from 4 to 8, as was observed with the Mundurukú. Individual differences in dot subtraction accuracy were predicted by dot enumeration skill with longer dot display durations but were predicted by visual working memory efficiency with shorter durations. Pica et al. (2004) attributed the Mundurukú participants' very poor subtraction to the absence of counting words, but our results show that a shift to reliance on visual working memory is a nonlinguistic factor that comes into play in the dot subtraction task when time to encode the dot arrays is limited. (c) 2016 APA, all rights reserved).

  14. Liquid-Crystal-Television Image Subtracters

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin; Liu, Hua-Kuang

    1988-01-01

    Two image-subtraction systems from output images that show differences between input images of two objects. First: differences appear as bright regions in otherwise dark output image. Second: differences and similarities shown by colors. All parts of two images processed simultaneously by optical components only; digital electronic processing of data not required. Concept offers potential for rapid, inexpensive comparison of images in such applications as automatic inspection, medical diagnosis, and robotic vision.

  15. Liquid-Crystal-Television Image Subtracters

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin; Liu, Hua-Kuang

    1988-01-01

    Two image-subtraction systems from output images that show differences between input images of two objects. First: differences appear as bright regions in otherwise dark output image. Second: differences and similarities shown by colors. All parts of two images processed simultaneously by optical components only; digital electronic processing of data not required. Concept offers potential for rapid, inexpensive comparison of images in such applications as automatic inspection, medical diagnosis, and robotic vision.

  16. Technical innovation: Multidimensional computerized software enabled subtraction computed tomographic angiography.

    PubMed

    Bhatia, Mona; Rosset, Antoine; Platon, Alexandra; Didier, Dominique; Becker, Christoph D; Poletti, Pierre-Alexandre

    2010-01-01

    Computed tomographic angiography (CTA) is a frequent noninvasive alternative to digital subtraction angiography. We previously reported the development of a new subtraction software to overcome limitations of adjacent bone and calcification in CT angiographic subtraction. Our aim was to further develop and improve this fast and automated computerized software, universally available for free use and compatible with most CT scanners, thus enabling better delineation of vascular structures, artifact reduction, and shorter reading times with potential clinical benefits. This computer-based free software will be available as an open source in the next release of OsiriX at the Web site http://www.osirix-viewer.com.

  17. Digital Radiography: A Technology Overview

    NASA Astrophysics Data System (ADS)

    Arnold, Ben A.

    1982-12-01

    Digital radiography, a term hardly recognized two years ago, has grown to become the talk of the radiology community and the excitement of many commercial companies. M2st of this attention has been directed toward digital subtraction intravenous angiography), although during this same time period, a variety of digital radiography apparatus and image processing techniques have been under development. In November of 1980 at the RSNA Conference in Chicago, three commercial digital angiography systems were announced by Philips, Technicare and ADAC Corporations. During this same time period, the University of Arizona was discussing the concept of a photo electronic radiology department2, the University of Pittsburg and Stanford University were investigating line scan radiography3,4 and approximately five laboratories were carrying out clinical IV angiography with digital video systems.5-9 These developments followed basic research programs in digital electronic and computerized imaging at various locations around the world. 10-18 In the spring of 1981 we attempted to review the state of digital radiography, focusing on the various detector systems and image acquisition approaches.19 Since that time, rapid advancements in digital radiography have occurred. A major conference was held on digital radiography at Stanford UniversityzO, a new area detector system for digital radiography was announced by Fuji Film Corporation, clinical testing began on the Picker line scan digital chest unit21, and improvements were made in selenium detectors for digital radiography. Several additional companies announced digital video angiography systems, bringing the total now to approximately 15 companies worldwide. Digital video subtraction angiography is now well established as an important clinical diagnostic procedure and a variety of improvements and extensions of digital angiography systems are now ongoing. Digital acquisition and storage systems are increasing in both speed and

  18. Image Quality and Stenosis Assessment of Non-Contrast-Enhanced 3-T Magnetic Resonance Angiography in Patients with Peripheral Artery Disease Compared with Contrast-Enhanced Magnetic Resonance Angiography and Digital Subtraction Angiography.

    PubMed

    Liu, Jiayi; Zhang, Nan; Fan, Zhaoyang; Luo, Nan; Zhao, Yike; Bi, Xiaoming; An, Jing; Chen, Zhong; Liu, Dongting; Wen, Zhaoying; Fan, Zhanming; Li, Debiao

    2016-01-01

    To evaluate the diagnostic performance of flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) magnetic resonance angiography (MRA) at 3 T for imaging infragenual arteries relative to contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA). A series of 16 consecutive patients with peripheral arterial disease (PAD) underwent a combined peripheral MRA protocol consisting of FSD-MRA for the calves and large field-of-view CE-MRA. DSA was performed on all patients within 1 week of the MR angiographies. Image quality and degree of stenosis was assessed by two readers with rich experience. Inter-observer agreement was determined using kappa statistics. Receiver operating characteristic (ROC) curve analysis determined the diagnostic value of FSD-MRA, CE-MRA, and CE-MRA combined with FSD-MRA (CE+FSD MRA) in predicting vascular stenosis. At the calf station, no significantly difference of subjective image quality scores was found between FSD-MRA and CE-MRA. Inter-reader agreement was excellent for both FSD-MRA and CE-MRA. Both of FSD-MRA and CE-MRA carry a stenosis overestimation risk relative to DSA standard. With DSA as the reference standard, ROC curve analysis showed that the area under the curve was largest for CE+FSD MRA. The greatest sensitivity and specificity were obtained when a cut-off stenosis score of 2 was used. In patients with severe PAD,3 T FSD-MRA provides good-quality diagnostic images without a contrast agent and is a good supplement for CE-MRA. CE+FSD MRA can improve the accuracy of vascular stenosis diagnosis.

  19. Magnetic resonance evaluation of renal artery stenosis in a swine model: performance of low-dose gadobutrol versus gadoterate meglumine in comparison with digital subtraction intra-arterial catheter angiography.

    PubMed

    Morelli, John N; Runge, Val M; Ai, Fei; Zhang, Wei; Li, Xiaoming; Schmitt, Peter; McNeal, Gary; Miller, Matthew; Lennox, Mark; Wusten, Oliver; Schoenberg, Stefan O; Attenberger, Ulrike I

    2012-06-01

    The aim of this study was to compare low-dose imaging with gadobutrol and gadoterate meglumine (Gd-DOTA) for evaluation of renal artery stenosis with 3-T magnetic resonance angiography (MRA) in a swine model. A total of 12 experimental animals were evaluated using equivalently dosed gadobutrol and Gd-DOTA for time-resolved and static imaging. For time-resolved imaging, the time-resolved imaging with stochastic trajectories (TWIST) technique (temporal footprint, 4.4 seconds) was used; a dose of 1 mL of gadobutrol was injected at 2 mL/s and a dose of 2 mL of Gd-DOTA was injected at both 2 and 4 mL/s. For a separate static acquisition, doses were doubled. The static scans were used for stenosis gradation and the time-resolved scans for comparison of enhancement dynamics, signal-to-noise ratio (SNR), and qualitative assessments. The average magnitude of difference in the stenosis measurements with static gadobutrol scans relative to digital subtraction intra-arterial catheter angiography (mean [SD], 7.4% [5.6%]) was less than with both the 2 mL/s (10.6% [6.2%]) and 4 mL/s (11.5% [7.8%]) Gd-DOTA MRA protocols. On time-resolved scans, peak signal-to-noise ratio was greatest with the gadobutrol protocol (P < 0.05), and the gadobutrol TWIST scan was preferred to the TWIST Gd-DOTA scan in terms of image quality and stenosis visualization in every case for every reader. Low-dose gadobutrol (~0.05 mmoL/kg) contrast-enhanced MRA results in improved accuracy of renal artery stenosis assessments relative to equivalently dosed Gd-DOTA at 3 T.

  20. Comparison of intra-arterial digital subtraction angiography using carbon dioxide by 'home made' delivery system and conventional iodinated contrast media in the evaluation of peripheral arterial occlusive disease of the lower limbs.

    PubMed

    Madhusudhan, K S; Sharma, S; Srivastava, D N; Thulkar, S; Mehta, S N; Prasad, G; Seenu, V; Agarwal, S

    2009-02-01

    To prospectively compare the feasibility, safety and diagnostic role of carbon dioxide (CO(2)) digital subtraction angiography (DSA) using a 'home made' delivery system with iodinated contrast medium (ICM) DSA in the evaluation of peripheral arterial occlusive diseases (PAOD) of lower limbs. Twenty-one patients (27 limbs; all men; mean age, 47.6 years) who presented with PAOD of lower limbs underwent DSA using both intra-arterial CO(2) and ICM. Conventional ICM DSA was performed first and used as gold standard. Carbon dioxide was then injected by hand using a locally improvised home made plastic bag delivery system. Patient tolerance was assessed subjectively. Arteries from aortic bifurcation to the ankle were independently evaluated by two radiologists and graded for stenosis using a five-point scale. For each patient, the quality of CO(2) DSA images were compared with the corresponding images of ICM DSA and an overall grade of 'good', 'acceptable' or 'poor' was assigned. Cohen's kappa coefficient was used to determine inter-observer agreement. Carbon dioxide opacified 86.2% (188/195) of major arteries and depicted stenosis adequately in 84.5% (191/226) of arterial segments. A good or acceptable image quality of CO(2) DSA was obtained in over 95% of patients. Infrapopliteal arteries were inadequately visualized. Mild pain was seen in six (28.6%) patients with both contrast agents; one patient developed severe pain during CO(2) DSA. Inter-observer agreement was good (k > 0.75) at 70% of the segments. Administration of CO(2) into lower limb arteries is well tolerated. Carbon dioxide DSA using the locally improvised home made delivery system is a feasible and safe alternative to ICM DSA in the evaluation of PAOD. It provides adequate imaging of arteries of lower extremities except infrapopliteal segments.

  1. Digital subtraction angiography during transjugular intrahepatic portosystemic shunt creation or revision: data on radiation exposure and image quality obtained using a standard and a low-dose acquisition protocol in a flat-panel detector-based system.

    PubMed

    Miraglia, Roberto; Maruzzelli, Luigi; Cortis, Kelvin; Tafaro, Corrado; Gerasia, Roberta; Parisi, Carmelo; Luca, Angelo

    2015-08-01

    To determine whether the use of a low-dose acquisition protocol (LDP) in digital subtraction angiography during transjugular intrahepatic portosystemic shunt (TIPS) creation/revision results in significant reduction of patient radiation exposure and adequate image quality, as compared to a default reference standard-dose acquisition protocol (SDP). Two angiographic runs were performed during TIPS creation/revision: the first following catheterization of the portal venous system and the second after stent deployment/angioplasty. Constant field of view, object to image-detector distance, and source to image-receptor distance were maintained in each patient during the two angiographic runs. 17 consecutive adult patients who underwent TIPS creation (n = 11) or TIPS revision (n = 6) from December 2013 to March 2014 were considered eligible for this single centre prospective study. In each patient, the LDP and the SDP were used in a random order for the two runs, with each patient serving as his/her own control. The dose-area product (DAP) was calculated for each image and compared. Image quality was graded by two interventional radiologists other than the operator. In all runs acquired with the LDP, image quality was considered adequate for a successful procedural outcome. The DAP per image of the LDP was numerically inferior as compared to the DAP per image of the SDP in all patients. The mean reduction in DAP per image was 75.24% ± 5.7% (p < 0. 001). Radiation exposure during TIPS creation/revision was significantly reduced by selecting a LDP in our flat-panel detector-based system, while maintaining adequate image quality.

  2. Myocardial ischemia during intravenous DSA in patients with cardiac disease

    SciTech Connect

    Hesselink, J.R.; Hayman, L.A.; Chung, K.J.; McGinnis, B.D.; Davis, K.R.; Taveras, J.M.

    1984-12-01

    A prospective study was performed for 48 patients who had histories of angina and were referred for digital subtraction angiography (DSA). Cardiac disease was graded according to the American Heart Association (AHA) functional classification system. Each patient received 2-5 injections of 40-ml diatrizoate meglumine and diatrizoate sodium at 15 ml per second in the superior vena cava. Of the 28 patients in functional Classes I or II, 11% had angina and 32% had definite ischemic ECG changes after the DSA injections. Of the patients in functional Class III 63% had angina, and 58% had definite ischemic ECG changes after the injections. These observed cardiac effects following bolus injections of hypertonic ionic contrast media indicate that special precautions are necessary when performing intravenous DSA examinations on this group of high risk patients.

  3. Intravenous Therapy.

    ERIC Educational Resources Information Center

    Galliart, Barbara

    Intended for teaching licensed practical nurses, this curriculum guide provides information related to the equipment and skills required for nursing care of patients needing intravenous (IV) therapy. It also explains the roles and responsibilities of the licensed practical nurse with regard to intravenous therapy. Each of the 15 instructional…

  4. Intravenous Therapy.

    ERIC Educational Resources Information Center

    Galliart, Barbara

    Intended for teaching licensed practical nurses, this curriculum guide provides information related to the equipment and skills required for nursing care of patients needing intravenous (IV) therapy. It also explains the roles and responsibilities of the licensed practical nurse with regard to intravenous therapy. Each of the 15 instructional…

  5. Pharmacokinetic-Pharmacodynamic Modeling of Intravenous and Oral Topiramate and Its Effect on the Symbol-Digit Modalities Test in Adult Healthy Volunteers

    PubMed Central

    Lim, Chay Ngee; Birnbaum, Angela K.; Brundage, Richard C.; Leppik, Ilo E.; Cloyd, James C.; Clark, Annie; Marino, Susan E.

    2016-01-01

    A sequential pharmacokinetic-pharmacodynamic (PK-PD) modeling approach was used to quantify the effects of a single dose of topiramate (100 or 200 mg) on working memory, attention, and psychomotor speed as measured by the Symbol-Digit Modalities Test (SDMT). Established on data pooled from 3 randomized, crossover studies in healthy subjects (19–55 years of age), using both oral and a novel stable-labeled intravenous (IV) formulation of topiramate, an inhibitory Emax model was found to characterize the topiramate concentration-SDMT score relationship well. At the EC50 of 2.85 μg/mL, this topiramate plasma concentration value was estimated to be associated with a 25.5% reduction of SDMT score relative to baseline. Age was an important determinant of the baseline SDMT score, with an estimated decrease of 1.13% in baseline SDMT score with every year of age. Moreover, this approach enabled the quantification of the practice effect observed with repeated administration of the neuropsychological test over shorter testing intervals than have previously been reported in the literature. The finding of a significant effect following a single dose of topiramate in the range widely used to treat migraine and epilepsy needs to be evaluated in a broader patient population undergoing chronic treatment, as the narrow range of resultant concentrations limits the generalizability of the findings. PMID:26395889

  6. Pharmacokinetic-Pharmacodynamic Modeling of Intravenous and Oral Topiramate and Its Effect on the Symbol-Digit Modalities Test in Adult Healthy Volunteers.

    PubMed

    Lim, Chay Ngee; Birnbaum, Angela K; Brundage, Richard C; Leppik, Ilo E; Cloyd, James C; Clark, Annie; Marino, Susan E

    2016-06-01

    A sequential pharmacokinetic-pharmacodynamic (PK-PD) modeling approach was used to quantify the effects of a single dose of topiramate (100 or 200 mg) on working memory, attention, and psychomotor speed as measured by the Symbol-Digit Modalities Test (SDMT). Established on data pooled from 3 randomized, crossover studies in healthy subjects (19-55 years of age), using both oral and a novel stable-labeled intravenous (IV) formulation of topiramate, an inhibitory Emax model was found to characterize the topiramate concentration-SDMT score relationship well. At the EC50 of 2.85 μg/mL, this topiramate plasma concentration value was estimated to be associated with a 25.5% reduction of SDMT score relative to baseline. Age was an important determinant of the baseline SDMT score, with an estimated decrease of 1.13% in baseline SDMT score with every year of age. Moreover, this approach enabled the quantification of the practice effect observed with repeated administration of the neuropsychological test over shorter testing intervals than have previously been reported in the literature. The finding of a significant effect following a single dose of topiramate in the range widely used to treat migraine and epilepsy needs to be evaluated in a broader patient population undergoing chronic treatment, as the narrow range of resultant concentrations limits the generalizability of the findings. © 2015, The American College of Clinical Pharmacology.

  7. Pulse subtraction Doppler

    NASA Astrophysics Data System (ADS)

    Mahue, Veronique; Mari, Jean Martial; Eckersley, Robert J.; Caro, Colin G.; Tang, Meng-Xing

    2010-01-01

    Recent advances have demonstrated the feasibility of molecular imaging using targeted microbubbles and ultrasound. One technical challenge is to selectively detect attached bubbles from those freely flowing bubbles and surrounding tissue. Pulse Inversion Doppler is an imaging technique enabling the selective detection of both static and moving ultrasound contrast agents: linear scatterers generate a single band Doppler spectrum, while non-linear scatterers generate a double band spectrum, one being uniquely correlated with the presence of contrast agents and non-linear tissue signals. We demonstrate that similar spectrums, and thus the same discrimination, can be obtained through a Doppler implementation of Pulse Subtraction. This is achieved by reconstructing a virtual echo using the echo generated from a short pulse transmission. Moreover by subtracting from this virtual echo the one generated from a longer pulse transmission, it is possible to fully suppress the echo from linear scatterers, while for non-linear scatterers, a signal will remain, allowing classical agent detection. Simulations of a single moving microbubble and a moving linear scatterer subject to these pulses show that when the virtual echo and the long pulse echo are used to perform pulsed Doppler, the power Doppler spectrum allows separation of linear and non-linear moving scattering. Similar results are obtained on experimental data acquired on a flow containing either microbubble contrast agents or linear blood mimicking fluid. This new Doppler method constitutes an alternative to Pulse Inversion Doppler and preliminary results suggest that similar dual band spectrums could be obtained by the combination of any non-linear detection technique with Doppler demodulation.

  8. Whole Number Subtraction -- An Analysis.

    ERIC Educational Resources Information Center

    Gilpin, John B.

    This document is intended as a resource for persons using, designing, or evaluating instructional materials in whole number subtraction. Its purpose is to provide conceptual machinery: (1) for describing/specifying subtraction tests and exercises and (2) for formulating related questions and conjectures. It is mainly a logical analysis subject to…

  9. On the Standard Rounding Rule for Addition and Subtraction.

    ERIC Educational Resources Information Center

    Lee, Wei; Mulliss, Christopher L.; Chu, Hung-Chih

    2000-01-01

    Investigates the commonly suggested rounding rule for addition and subtraction including its derivation from a basic assumption. Uses Monte-Carlo simulations to show that this rule predicts the minimum number of significant digits needed to preserve precision 100% of the time. (Author/KHR)

  10. Enriching Addition and Subtraction Fact Mastery through Games

    ERIC Educational Resources Information Center

    Bay-Williams, Jennifer M.; Kling, Gina

    2014-01-01

    The learning of "basic facts"--single-digit combinations for addition, subtraction, multiplication, and division--has long been a focus of elementary school mathematics. Many people remember completing endless worksheets, timed tests, and flash card drills as they attempted to "master" their basic facts as children. However,…

  11. Enriching Addition and Subtraction Fact Mastery through Games

    ERIC Educational Resources Information Center

    Bay-Williams, Jennifer M.; Kling, Gina

    2014-01-01

    The learning of "basic facts"--single-digit combinations for addition, subtraction, multiplication, and division--has long been a focus of elementary school mathematics. Many people remember completing endless worksheets, timed tests, and flash card drills as they attempted to "master" their basic facts as children. However,…

  12. The Use of Procedural Knowledge in Simple Addition and Subtraction Problems

    ERIC Educational Resources Information Center

    Fayol, Michel; Thevenot, Catherine

    2012-01-01

    In a first experiment, adults were asked to solve one-digit additions, subtractions and multiplications. When the sign appeared 150 ms before the operands, addition and subtraction were solved faster than when the sign and the operands appeared simultaneously on screen. This priming effect was not observed for multiplication problems. A second…

  13. Tumor volume, luxury perfusion, and regional blood volume changes in man visualized by subtraction computerized tomography.

    PubMed

    Penn, R D; Walser, R; Kurtz, D; Ackerman, L

    1976-04-01

    Computer and photographic methods for producing subtractions of computerized axial tomographic (CAT) scans have been developed. By subtracting point for point a normal scan from one taken after intravenous infusion of contrast material, a picture of the contrast in the cerebral vessels is created. By this method, tumor size and degree of vascularity may be assessed. Furthermore, abnormalities in perfusion and changes in blood volume due to mass effects and edema may be detected. Subtracting scans should add to the diagnostic potential of CAT and provide a noninvasive way to study vascular changes in cerebral disease.

  14. Synchrotron-based intravenous cerebral angiography in a small animal model

    NASA Astrophysics Data System (ADS)

    Kelly, Michael E.; Schültke, Elisabeth; Fiedler, Stephan; Nemoz, Christian; Guzman, Raphael; Corde, Stephanie; Esteve, Francois; LeDuc, Geraldine; Juurlink, Bernhard H. J.; Meguro, Kotoo

    2007-02-01

    K-edge digital subtraction angiography (KEDSA), a recently developed synchrotron-based technique, utilizes monochromatic radiation and allows acquisition of high-quality angiography images after intravenous administration of contrast agent. We tested KEDSA for its suitability for intravenous cerebral angiography in an animal model. Adult male New Zealand rabbits were subjected to either angiography with conventional x-ray equipment or synchrotron-based intravenous KEDSA, using an iodine-based contrast agent. Angiography with conventional x-ray equipment after intra-arterial administration of contrast agent demonstrated the major intracranial vessels but no smaller branches. KEDSA was able to visualize the major intracranial vessels as well as smaller branches in both radiography mode (planar images) and tomography mode. Visualization was achieved with as little as 0.5 ml kg-1 of iodinated contrast material. We were able to obtain excellent visualization of the cerebral vasculature in an animal model using intravenous injection of contrast material, using synchrotron-based KEDSA.

  15. Inverse reference in subtraction performance: an analysis from arithmetic word problems.

    PubMed

    Orrantia, Josetxu; Rodríguez, Laura; Múñez, David; Vicente, Santiago

    2012-01-01

    Studies of elementary calculation have shown that adults solve basic subtraction problems faster with problems presented in addition format (e.g., 6 ± = 13) than in standard subtraction format (e.g., 13 - 6 = ). Therefore, it is considered that adults solve subtraction problems by reference to the inverse operation (e.g., for 13 - 6 = 7, "I know that 13 is 6 + 7") because presenting the subtraction problem in addition format does not require the mental rearrangement of the problem elements into the addition format. In two experiments, we examine whether adults' use of addition to solve subtractions is modulated by the arrangement of minuend and subtrahend, regardless of format. To this end, we used arithmetic word problems since single-digit problems in subtraction format would not allow the subtrahend to appear before the minuend. In Experiment 1, subtractions were presented by arranging minuend and subtrahend according to previous research. In Experiment 2, operands were reversed. The overall results showed that participants benefited from word problems where the subtrahend appears before the minuend, including subtractions in standard subtraction format. These findings add to a growing body of literature that emphasizes the role of inverse reference in adults' performance on subtractions.

  16. Intravenous Pyelogram (IVP)

    MedlinePlus

    ... News Physician Resources Professions Site Index A-Z Intravenous Pyelogram (IVP) Intravenous pyelogram (IVP) is an x- ... the limitations of IVP exams? What is an Intravenous Pyelogram (IVP)? An intravenous pyelogram (IVP) is an ...

  17. Subtraction of background fluorescence in multiharmonic frequency-domain fluorimetry.

    PubMed

    Periasamy, N; Verkman, A S

    1992-02-14

    Background fluorescence is a major concern in time-resolved microfluorimetry studies of biological samples. A general method for subtraction of an arbitrary background signal in measurements of lifetime and anisotropy decay by multiharmonic Fourier transform spectroscopy is presented. Multifrequency phase and modulation values are measured in parallel by transformation of digitized time-domain waveforms into the frequency domain. For subtraction of background, time-domain waveforms are acquired for emission and reference photomultipliers for sample (e.g., cell containing fluorophore) and blank (e.g., unlabeled cell). Time-domain waveforms obtained in a series of measurements (e.g., sample and blank for parallel and perpendicular orientations of an emission polarizer) are time-justified by least-squares fitting of reference channel waveforms or by phase comparison of the first Fourier harmonics of the reference channel. Background is then subtracted directly in the time domain, and the subtracted waveform is Fourier transformed to the frequency domain for analysis of lifetime or anisotropy decay. This approach yielded excellent background correction over a wide range of background intensities and decay profiles. The method was tested in cuvette fluorimetry with fluorescein and acridine orange and in fluorescence microscopy with living MDCK cells loaded with the pH indicator BCECF. Sample lifetimes and rotational parameters could be recovered accurately with greater than 50% of the signal arising from background. These results establish a direct and practical approach to subtraction of background in complex biological and chemical samples studied by frequency-domain fluorimetry.

  18. Color Addition and Subtraction Apps

    NASA Astrophysics Data System (ADS)

    Ruiz, Frances; Ruiz, Michael J.

    2015-10-01

    Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step in understanding mathematical representations of RGB color. Finally, color addition and subtraction are presented for the X11 colors from web design to illustrate yet another real-life application of color mixing.

  19. "Subtractive" Bilingualism in Northern Belize.

    ERIC Educational Resources Information Center

    Rubinstein, Robert A.

    "Subtractive" bilingualism in Northern Belize is analyzed based on an extension of a model by Wallace Lambert. The impact of English language instruction on Spanish speaking children in Corozal Town, the northernmost urban center in the British colony of Belize, Central America, is described. This description extends an earlier account…

  20. Color Addition and Subtraction Apps

    ERIC Educational Resources Information Center

    Ruiz, Frances; Ruiz, Michael J.

    2015-01-01

    Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step…

  1. Color Addition and Subtraction Apps

    ERIC Educational Resources Information Center

    Ruiz, Frances; Ruiz, Michael J.

    2015-01-01

    Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step…

  2. Evolution of digital angiography systems.

    PubMed

    Brigida, Raffaela; Misciasci, Teresa; Martarelli, Fabiola; Gangitano, Guido; Ottaviani, Pierfrancesco; Rollo, Massimo; Marano, Pasquale

    2003-01-01

    The innovations introduced by digital subtraction angiography in digital radiography are briefly illustrated with the description of its components and functioning. The pros and cons of digital subtraction angiography are analyzed in light of present and future imaging technologies. In particular, among advantages there are: automatic exposure, digital image subtraction, digital post-processing, high number of images per second, possible changes in density and contrast. Among disadvantages there are: small round field of view, geometric distortion at the image periphery, high sensitivity to patient movements, not very high spatial resolution. At present, flat panel detectors represent the most suitable substitutes for digital subtraction angiography, with the introduction of novel solutions for those artifacts which for years have hindered its diagnostic validity. The concept of temporal artifact, reset light and possible future evolutions of this technology that may afford both diagnostic and protectionist advantages, are analyzed.

  3. Preschoolers' Understanding of Subtraction-Related Principles

    ERIC Educational Resources Information Center

    Baroody, Arthur J.; Lai, Meng-lung; Li, Xia; Baroody, Alison E.

    2009-01-01

    Little research has focused on an informal understanding of subtractive negation (e.g., 3 - 3 = 0) and subtractive identity (e.g., 3 - 0 = 3). Previous research indicates that preschoolers may have a fragile (i.e., unreliable or localized) understanding of the addition-subtraction inverse principle (e.g., 2 + 1 - 1 = 2). Recognition of a small…

  4. Sky subtraction with fiber spectrographs

    NASA Astrophysics Data System (ADS)

    Lissandrini, C.; Cristiani, S.; La Franca, F.

    1994-11-01

    The sky-subtraction performance of multifiber spectrographs is discussed, analyzing in detail the case of the OPTOPUS system at the 3.6-m European Space Observatory (ESO) telescope at La Silla. A standard technique, based on flat fields obtained with a uniformly illuminated screen on the dome, provides poor results. A new method has been developed, using the (O I) emission line at 5577 A as a calibrator of the fiber transmittance, taking into account the diffuse light and the influence of each fiber on the adjacent ones, and correcting for the effects of the image distortions on the sky sampling. In this way the accuracy of the sky subtraction improves from 2%-8% to 1.3%-1.6%.

  5. Bilateral fitting subtracting confocal microscopy.

    PubMed

    Zhao, Weiqian; Sheng, Zhong; Qiu, Lirong; Wang, Yun; Shao, Rongjun

    2016-12-20

    This paper proposes a bilateral fitting subtracting confocal microscopy (BFSCM) based on the optical arrangement of conventional confocal microscopy (CM). BFSCM first uses the data in both sides of a confocal axial response curve, which are very sensitive to the axial position of the sample, for respective linear fitting to obtain two fitting straight lines, and then obtains a difference confocal line by subtraction of the two fitting lines. Finally, it calculates the zero position of the difference confocal line to precisely capture the focus position of the confocal system, and thereby achieving a high-precision measurement of the 3D structure of the sample. The theoretical analyses and experiments indicate that BFSCM can improve the axial resolution, and has anti-interference capability and focusing ability with bipolar absolute zero point tracking, while it does not change the structure and lateral resolution of CM. BFSCM provides a novel method for the improvement of CM axial resolution.

  6. Embossed radiography utilizing energy subtraction.

    PubMed

    Osawa, Akihiro; Watanabe, Manabu; Sato, Eiichi; Matsukiyo, Hiroshi; Enomoto, Toshiyuki; Nagao, Jiro; Abderyim, Purkhet; Aizawa, Katsuo; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Ehara, Shigeru; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2009-01-01

    Currently, it is difficult to carry out refraction-contrast radiography by using a conventional X-ray generator. Thus, we developed an embossed radiography system utilizing dual-energy subtraction for decreasing the absorption contrast in unnecessary regions, and the contrast resolution of a target region was increased by use of image-shifting subtraction and a linear-contrast system in a flat panel detector (FPD). The X-ray generator had a 100-microm-focus tube. Energy subtraction was performed at tube voltages of 45 and 65 kV, a tube current of 0.50 mA, and an X-ray exposure time of 5.0 s. A 1.0-mm-thick aluminum filter was used for absorbing low-photon-energy bremsstrahlung X-rays. Embossed radiography was achieved with cohesion imaging by use of the FPD with pixel sizes of 48 x 48 microm, and the shifting dimension of an object in the horizontal direction ranged from 100 to 200 microm. At a shifting distance of 100 mum, the spatial resolutions in the horizontal and vertical directions measured with a lead test chart were both 83 microm. In embossed radiography of non-living animals, we obtained high-contrast embossed images of fine bones, gadolinium oxide particles in the kidney, and coronary arteries approximately 100 microm in diameter.

  7. Subtraction Radiographic Assessment of Underlying Dentin After Partial Carious Dentin Removal in Primary Teeth.

    PubMed

    Phonghanyudh, Araya; Ruangdit, Chayathorn; Pornprasertsuk-D Amrongsri, Suchaya; Phanthumvanit, Prathip

    2017-09-21

    To assess the one-year outcome of glass-ionomer cement (GIC) restorations with partial carious dentin removal in primary molars using digital subtraction radiographs. Children ages 6-8 years were recruited. Forty-nine primary molars with deep carious lesions were studied. The carious dentin was removed at the dentoenamel junction (DEJ) and restored with GIC. Digital radiographs were taken immediately after restoration, and at 6 and 12 months after restoration. The sets of digital radiographs were subtracted and analysed using Image-Pro Plus software. At the 12-month follow-up, 38 of the original 49 primary molars were analysed. No postoperative pain or signs of pulp pathology were reported. 76% and 87% of molars showed an increase in density of the studied areas compared to control areas at 6- and 12- month follow-ups, respectively. The density of digital subtraction radiographs increased to 5.3 and 8.2 at 6 and 12 months from baseline, respectively. The mean density of the areas under restoration at 6 months and 12 months was statistically significantly higher than at baseline (paired t-test; p < 0.05). Using digital subtraction radiographs, GIC restorations with partial carious dentin removal in primary molars showed a high potential for dentin remineralisation after 1 year.

  8. Two-dimensional real-time imaging system for subtraction angiography using an iodine filter

    SciTech Connect

    Umetani, K.; Ueda, K. ); Takeda, T.; Anno, I.; Itai, Y. ); Akisada, M.; Nakajima, T. )

    1992-01-01

    A new type of subtraction imaging system was developed using an iodine filter and a single-energy broad bandwidth monochromatized x ray. The x-ray images of coronary arteries made after intravenous injection of a contrast agent are enhanced by an energy-subtraction technique. Filter chopping of the x-ray beam switches energies rapidly, so that a nearly simultaneous pair of filtered and nonfiltered images can be made. By using a high-speed video camera, a pair of two 512 {times} 512 pixel images can be obtained within 9 ms. Three hundred eighty-four images (raw data) are stored in a 144-Mbyte frame memory. After phantom studies, {ital in} {ital vivo} subtracted images of coronary arteries in dogs were obtained at a rate of 15 images/s.

  9. Addition and Subtraction, and Algorithms in General

    ERIC Educational Resources Information Center

    Fielker, David

    2007-01-01

    The juxtaposition of articles by Ian Thompson and Ian Sugarman in "MT202" on addition and subtraction respectively engendered some bemused thoughts in this author, who for some years has been sheltered from controversy by retirement. In this article, Fielker shares some thoughts on addition and subtraction raised by Thompson and Sugarman in their…

  10. A geometric approach to spectral subtraction

    PubMed Central

    Lu, Yang; Loizou, Philipos C.

    2008-01-01

    The traditional power spectral subtraction algorithm is computationally simple to implement but suffers from musical noise distortion. In addition, the subtractive rules are based on incorrect assumptions about the cross terms being zero. A new geometric approach to spectral subtraction is proposed in the present paper that addresses these shortcomings of the spectral subtraction algorithm. A method for estimating the cross terms involving the phase differences between the noisy (and clean) signals and noise is proposed. Analysis of the gain function of the proposed algorithm indicated that it possesses similar properties as the traditional MMSE algorithm. Objective evaluation of the proposed algorithm showed that it performed significantly better than the traditional spectral subtractive algorithm. Informal listening tests revealed that the proposed algorithm had no audible musical noise. PMID:19122867

  11. Flat detector computed tomography angiography with intravenous contrast application: feasibility for visualization of cerebral arterial vasculature.

    PubMed

    Saake, Marc; Breuer, Lorenz; Goelitz, Philipp; Ott, Sabine; Struffert, Tobias; Doerfler, Arnd

    2013-07-01

    The aim of our study was to evaluate flat detector computed tomography angiography with peripheral intravenous contrast material application (FD-CTA) for visualization of cerebral arteries in comparison with intravenous multidetector computed tomography angiography (CTA) and intraarterial digital subtraction angiography (DSA). The study was approved by the local institutional review board and informed consent was obtained by all participants. Ten patients underwent FD-CTA, CTA, and DSA of the cerebral arterial vasculature for suspected cerebrovascular disease. The image data were evaluated by two readers in consensus for the visualization of cerebral arterial segments on a 5-point scale (0 = vessel cannot be distinguished; 4 = excellent image quality). The Wilcoxon signed-rank test was used for statistical analysis. Note that P < .05 was considered to indicate a significant difference. The depiction of cerebral arterial segments with FD-CTA was significantly superior compared to CTA in most vessel segments (P < .05 in 20 of 23 anatomic regions) and was without significant difference compared with DSA in large and medium intracranial vessels. The results suggest that the cerebral arteries can be visualized by FD-CTA in high resolution, in many vessel segments comparable to DSA. Copyright © 2012 by the American Society of Neuroimaging.

  12. Helping Students to Connect Subtraction Strategies Improves Mathematical Reasoning for Students and Teachers

    ERIC Educational Resources Information Center

    Sci, Eve

    2011-01-01

    After administering an end of unit assessment written by the school's math program, teachers of three second grade classes in a New York City school noticed a majority of the students had not demonstrated mastery of subtracting two, two-digit numbers. The teachers worked with the school's math coach to implement an instructional unit that required…

  13. Entanglement entropy of subtracted geometry black holes

    NASA Astrophysics Data System (ADS)

    Cvetič, Mirjam; Saleem, Zain H.; Satz, Alejandro

    2014-09-01

    We compute the entanglement entropy of minimally coupled scalar fields on subtracted geometry black hole backgrounds, focusing on the logarithmic corrections. We notice that matching between the entanglement entropy of original black holes and their subtracted counterparts is only at the order of the area term. The logarithmic correction term is not only different but also, in general, changes sign in the subtracted case. We apply Harrison transformations to the original black holes and find out the choice of the Harrison parameters for which the logarithmic corrections vanish.

  14. The research about the quick algorithm of subtracting the DTM

    NASA Astrophysics Data System (ADS)

    Chian, Tao; Li, Yan; Geng, Juan

    2007-06-01

    There is some relationship between the Digital Surface Model (DSM) and the Digital Terrain Model (DTM). The contents they express are relative: DSM expresses the height we focus on about the surface of the ground, including the terrain and the objects on it, and DTM only gives the height of the terrain excluding the objects above it. DSM have the information of DTM, therefore it provides us a chance to subtract the DTM from the DSM. Mathematical morphology is a new method applied to Imagery processing and pattern recognition fields. It provides an effective method of subtracting DTM from DSM. But in practical application, the original calculations of these two are in low efficiency. Especially when it comes to a large template or huge block data, the computation speed can be a very headache question. This paper is studying the implementing process of the Open and the Close operators, especially the Erode and the Dilate calculations. Then we have developed two kinds of quick algorithms, which are aim to avoid the repeated calculation, and to enhance the efficiency sharply. The step of the two operations also should be refined, while the disposals are different from each other depending on the distinct configuration of these two kinds of algorithms.

  15. Compressive Sensing for Background Subtraction

    DTIC Science & Technology

    2009-12-20

    i) reconstructing an image using only a single optical pho- todiode (infrared, hyperspectral, etc.) along with a digital micromirror device ( DMD ...robust against packet drops. The SPC architecture uses a DMD to generate a random sampling pattern and sends the resulting inner product of the incident...a set of M consecutive measurements can be made about the scene using the same optical sensor, which form the measurement vector y. The current DMD

  16. Intravenous paracetamol (acetaminophen).

    PubMed

    Duggan, Sean T; Scott, Lesley J

    2009-01-01

    Intravenous paracetamol (rINN)/intravenous acetaminophen (USAN) is an analgesic and antipyretic agent, recommended worldwide as a first-line agent for the treatment of pain and fever in adults and children. In double-blind clinical trials, single or multiple doses of intravenous paracetamol 1 g generally provided significantly better analgesic efficacy than placebo treatment (as determined by primary efficacy endpoints) in adult patients who had undergone dental, orthopaedic or gynaecological surgery. Furthermore, where evaluated, intravenous paracetamol 1 g generally showed similar analgesic efficacy to a bioequivalent dose of propacetamol, and a reduced need for opioid rescue medication. In paediatric surgical patients, recommended doses of intravenous paracetamol 15 mg/kg were not significantly different from propacetamol 30 mg/kg for the treatment of pain, and showed equivocal analgesic efficacy compared with intramuscular pethidine 1 mg/kg in several randomized, active comparator-controlled studies. In a randomized, noninferiority study in paediatric patients with an infection-induced fever, intravenous paracetamol 15 mg/kg treatment was shown to be no less effective than propacetamol 30 mg/kg in terms of antipyretic efficacy. Intravenous paracetamol was well tolerated in clinical trials, having a tolerability profile similar to placebo. Additionally, adverse reactions emerging from the use of the intravenous formulation of paracetamol are extremely rare (<1/10 000). [table: see text].

  17. Minimal subtraction and momentum subtraction in quantum chromodynamics at two-loop order

    SciTech Connect

    Braaten, E.; Leveille, J.P.

    1981-09-01

    The momentum-subtraction coupling constant ..cap alpha../sub MOM/ yields consistently smaller one-loop corrections to many quantum-chromodynamics (QCD) processes than the minimal-subtraction couplings ..cap alpha../sub MS/ and ..cap alpha../sub M/S. By shifting the renormalization scale ..mu.. of ..cap alpha../sub MS/(..mu..), we obtain a minimal-subtraction coupling with the same small one-loop corrections. It is shown, by studying the effective charges of QCD, that at two-loop order this coupling constant will continue to yield corrections to physical quantities that are comparable to those obtained by momentum subtraction. We also introduce a momentum-subtraction scheme which treats the triple-gluon, quark, and ghost vertices equally at one-loop order and is more convenient for higher-order calculations than the MOM scheme.

  18. Digital Subtraction MR Angiography Roadmapping for Magnetic Steerable Catheter Tracking

    PubMed Central

    Martin, Alastair J.; Lillaney, Prasheel; Saeed, Maythem; Losey, Aaron D.; Settecase, Fabio; Evans, Lee; Arenson, Ronald L.; Wilson, Mark W.; Hetts, Steven W.

    2014-01-01

    Purpose To develop a high temporal resolution MR imaging technique that could be employed with magnetically-assisted remote control (MARC) endovascular catheters. Materials and Methods A technique is proposed based on selective intra-arterial injections of dilute MR contrast at the beginning of a fluoroscopic MR angiography acquisition. The initial bolus of contrast is used to establish a vascular roadmap upon which MARC catheters can be tracked. The contrast to noise ratio of the achieved roadmap was assessed in phantoms and in a swine animal model. The ability of the technique to permit navigation of activated MARC catheters through arterial branch points was evaluated. Results The roadmapping mode proved effective in phantoms for tracking objects and achieved a contrast to noise ratio of 35.7 between the intra and extra-vascular space. In vivo, the intra-arterial enhancement strategy produced roadmaps with a contrast to noise ratio of 42.0. The artifact produced by MARC catheter activation provided signal enhancement patterns on the roadmap that experienced interventionalists could track through vascular structures. Conclusion A roadmapping approach with intra-arterial CE-MRA is introduced for navigating the MARC catheter. The technique mitigates the artifact produced by the MARC catheter, greatly limits the required SAR, permits regular roadmap updates due to the low contrast agent requirements, and proved effective in the in vivo setting. PMID:24797218

  19. The spectrum of static subtracted geometries

    NASA Astrophysics Data System (ADS)

    Andrade, Tomás; Castro, Alejandra; Cohen-Maldonado, Diego

    2017-05-01

    Subtracted geometries are black hole solutions of the four dimensional STU model with rather interesting ties to asymptotically flat black holes. A peculiar feature is that the solutions to the Klein-Gordon equation on this subtracted background can be organized according to representations of the conformal group SO(2, 2). We test if this behavior persists for the linearized fluctuations of gravitational and matter fields on static, electrically charged backgrounds of this kind. We find that there is a subsector of the modes that do display conformal symmetry, while some modes do not. We also discuss two different effective actions that describe these subtracted geometries and how the spectrum of quasinormal modes is dramatically different depending upon the action used.

  20. Subtraction CT angiography for the detection of intracranial aneurysms: A meta-analysis

    PubMed Central

    FENG, TIAN-YING; HAN, XUE-FENG; LANG, RUI; WANG, FEI; WU, QIONG

    2016-01-01

    The aim of this meta-analysis was to investigate the accuracy of subtraction computed tomography angiography (CTA) for diagnosing intracranial aneurysms. A systematic literature search up to January 1, 2013 was performed in PubMed. Two independent reviewers selected 8 studies that compared subtraction CTA with digital subtraction angiography. Data from the studies were used to construct a 2×2 contingency table on a per-patient basis in ≥5 diseased and 5 non-diseased patients, with additional data on a per-aneurysm basis. Overall, subtraction CTA had a pooled sensitivity of 99% [95% confidence interval (CI), 95–100%] and specificity of 94% (95% CI, 86–97%) for detecting and ruling out cerebral aneurysms, respectively, on a per-patient basis. On a per-aneurysm basis, the pooled sensitivity was 96% (95% CI, 90–99%), and the specificity was 91% (95% CI, 85–95%). In conclusion, subtraction CTA is a highly sensitive, specific and non-invasive method for the diagnosis and evaluation of intracranial aneurysms. PMID:27168830

  1. Additive-subtractive phase-modulated electronic speckle interferometry: analysis of fringe visibility.

    PubMed

    Pouet, B F; Krishnaswamy, S

    1994-10-01

    Fringe-visibility issues of additive-subtractive phase-modulated (ASPM) electronic speckle pattern interferometry (ESPI) are explored. ASPM ESPI is a three-step method in which additive-speckle images are acquired rapidly in an analog fashion in every frame of a video sequence, a speckle phase modulation is intentionally introduced between frames, and a digital subtraction of consecutive pairs of additive-speckle images is performed. We show that this scheme has the good high-frequency noise immunity associated with additive-ESPI techniques as well as the good fringe visibility associated with subtractive-ESPI techniques. The method has better fringe visibility than can be obtained with purely additive ESPI and also does not suffer from the fringe distortions that can occur with subtractive ESPI in the presence of high-frequency noise. We show that even if full speckle decorrelation were to occur between the two additive speckle images that are to be subtracted, the visibility of ASPM ESPI fringes can be made to approach unity by suitable adjustment of the reference-to-object beam-intensity ratio.

  2. Magnitude subtraction vs. complex subtraction in dynamic contrast-enhanced 3D-MR angiography: basic experiments and clinical evaluation.

    PubMed

    Naganawa, S; Ito, T; Iwayama, E; Fukatsu, H; Ishiguchi, T; Ishigaki, T; Ichinose, N

    1999-11-01

    Magnitude subtraction and complex subtraction in dynamic contrast-enhanced three-dimensional magnetic resonance (3D-MR) angiography were compared using a phantom and 23 human subjects. In phantom studies, complex subtraction showed far better performance than magnitude subtraction, especially for longer echo times, with thicker slices, and without fat suppression. With complex subtraction, non-fat-suppressed studies showed contrast-to-noise ratios comparable to those in fat-suppressed studies. In human subjects, complex subtraction was superior to magnitude subtraction in 9 subjects, but comparable to magnitude subtraction in 14 subjects. There were no cases in which magnitude subtraction was superior to complex subtraction. Although the differences observed in human studies when complex subtraction was applied with thinner slices, shorter echo times, and the fat-suppression technique were not as pronounced as those seen in phantom studies, complex subtraction should be performed in dynamic contrast-enhanced 3D-MR angiography because there are no drawbacks in complex subtraction. Further research is necessary to assess the feasibility of dynamic contrast-enhanced 3D-MR angiography without fat suppression in human subjects using complex subtraction, as suggested by the results of phantom studies. If it is found to be feasible, dynamic contrast-enhanced 3D-MR angiography without fat suppression using complex subtraction may prove to be a robust technique that eliminates the need for shimming and can reduce the acquisition time. J. Magn. Reson. Imaging 1999;10:813-820.

  3. Follow-up of intracranial aneurysms treated by flow diverter: comparison of three-dimensional time-of-flight MR angiography (3D-TOF-MRA) and contrast-enhanced MR angiography (CE-MRA) sequences with digital subtraction angiography as the gold standard.

    PubMed

    Attali, Jonathan; Benaissa, Azzedine; Soize, Sébastien; Kadziolka, Krzysztof; Portefaix, Christophe; Pierot, Laurent

    2016-01-01

    Follow-up of intracranial aneurysms treated by flow diverter with MRI is complicated by imaging artifacts produced by these devices. This study compares the diagnostic accuracy of three-dimensional time-of-flight MR angiography (3D-TOF-MRA) and contrast-enhanced MRA (CE-MRA) at 3 T for the evaluation of aneurysm occlusion and parent artery patency after flow diversion treatment, with digital subtraction angiography (DSA) as the gold standard. Patients treated with flow diverters between January 2009 and January 2013 followed by MRA at 3 T (3D-TOF-MRA and CE-MRA) and DSA within a 48 h period were included in a prospective single-center study. Aneurysm occlusion was assessed with full and simplified Montreal scales and parent artery patency with three-grade and two-grade scales. Twenty-two patients harboring 23 treated aneurysms were included. Interobserver agreement using simplified scales for occlusion (Montreal) and parent artery patency were higher for DSA (0.88 and 0.61) and CE-MRA (0.74 and 0.55) than for 3D-TOF-MRA (0.51 and 0.02). Intermodality agreement was higher for CE-MRA (0.88 and 0.32) than for 3D-TOF-MRA (0.59 and 0.11). CE-MRA yielded better accuracy than 3D-TOF-MRA for aneurysm remnant detection (sensitivity 83% vs 50%; specificity 100% vs 100%) and for the status of the parent artery (specificity 63% vs 32%; sensitivity 100% vs 100%). At 3 T, CE-MRA is superior to 3D-TOF-MRA for the evaluation of aneurysm occlusion and parent artery patency after flow diversion treatment. However, intraluminal evaluation remains difficult with MRA regardless of the sequence used. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  4. Diagnosis of Subtraction Bugs Using Bayesian Networks

    ERIC Educational Resources Information Center

    Lee, Jihyun; Corter, James E.

    2011-01-01

    Diagnosis of misconceptions or "bugs" in procedural skills is difficult because of their unstable nature. This study addresses this problem by proposing and evaluating a probability-based approach to the diagnosis of bugs in children's multicolumn subtraction performance using Bayesian networks. This approach assumes a causal network relating…

  5. Verification of IEEE Compliant Subtractive Division Algorithms

    NASA Technical Reports Server (NTRS)

    Miner, Paul S.; Leathrum, James F., Jr.

    1996-01-01

    A parameterized definition of subtractive floating point division algorithms is presented and verified using PVS. The general algorithm is proven to satisfy a formal definition of an IEEE standard for floating point arithmetic. The utility of the general specification is illustrated using a number of different instances of the general algorithm.

  6. Polygon Subtraction in 2 or 3 Dimensions

    SciTech Connect

    Wilson, John E.

    2013-10-01

    When searching for computer code to perform the ubiquitous task of subtracting one polygon from another, it is difficult to find real examples and detailed explanations. This paper outlines the step-by-step process necessary to accomplish this basic task.

  7. Children's Understanding of Addition and Subtraction Concepts

    ERIC Educational Resources Information Center

    Robinson, Katherine M.; Dube, Adam K.

    2009-01-01

    After the onset of formal schooling, little is known about the development of children's understanding of the arithmetic concepts of inversion and associativity. On problems of the form a+b-b (e.g., 3+26-26), if children understand the inversion concept (i.e., that addition and subtraction are inverse operations), then no calculations are needed…

  8. Children's Understanding of Addition and Subtraction Concepts

    ERIC Educational Resources Information Center

    Robinson, Katherine M.; Dube, Adam K.

    2009-01-01

    After the onset of formal schooling, little is known about the development of children's understanding of the arithmetic concepts of inversion and associativity. On problems of the form a+b-b (e.g., 3+26-26), if children understand the inversion concept (i.e., that addition and subtraction are inverse operations), then no calculations are needed…

  9. Diagnosis of Subtraction Bugs Using Bayesian Networks

    ERIC Educational Resources Information Center

    Lee, Jihyun; Corter, James E.

    2011-01-01

    Diagnosis of misconceptions or "bugs" in procedural skills is difficult because of their unstable nature. This study addresses this problem by proposing and evaluating a probability-based approach to the diagnosis of bugs in children's multicolumn subtraction performance using Bayesian networks. This approach assumes a causal network relating…

  10. Simple circuit performs binary addition and subtraction

    NASA Technical Reports Server (NTRS)

    Cliff, R. A.; Schaefer, D. H.

    1965-01-01

    Ripple adder reduces the number of logic circuits required to preform binary addition and subtraction. The adder uses dual input and delayed output flip-flops in one register. The contents of this register are summed with those of a standard register through conventional AND/gates.

  11. An experimental implementation of chemical subtraction.

    PubMed

    Chen, Shao-Nong; Turner, Allison; Jaki, Birgit U; Nikolic, Dejan; van Breemen, Richard B; Friesen, J Brent; Pauli, Guido F

    2008-03-13

    A preparative analytical method was developed to selectively remove ("chemically subtract") a single compound from a complex mixture, such as a natural extract or fraction, in a single step. The proof of concept is demonstrated by the removal of pure benzoic acid (BA) from cranberry (Vaccinium macrocarpon Ait.) juice fractions that exhibit anti-adhesive effects versus uropathogenic Escherichia coli. Chemical subtraction of BA, representing a major constituent of the fractions, eliminates the potential in vitro interference of the bacteriostatic effect of BA on the E. coli anti-adherence action measured in bioassays. Upon BA removal, the anti-adherent activity of the fraction was fully retained, 36% inhibition of adherence in the parent fraction at 100mug/mL increased to 58% in the BA-free active fraction. The method employs countercurrent chromatography (CCC) and operates loss-free for both the subtracted and the retained portions as only liquid-liquid partitioning is involved. While the high purity (97.47% by quantitative (1)H NMR) of the subtracted BA confirms the selectivity of the method, one minor impurity was determined to be scopoletin by HR-ESI-MS and (q)HNMR and represents the first coumarin reported from cranberries. A general concept for the selective removal of phytoconstituents by CCC is presented, which has potential broad applicability in the biological evaluation of medicinal plant extracts and complex pharmaceutical preparations.

  12. Children's Profiles of Addition and Subtraction Understanding

    ERIC Educational Resources Information Center

    Canobi, Katherine H.

    2005-01-01

    The current research explored children's ability to recognize and explain different concepts both with and without reference to physical objects so as to provide insight into the development of children's addition and subtraction understanding. In Study 1, 72 7- to 9-year-olds judged and explained a puppet's activities involving three conceptual…

  13. Transactional Algorithm for Subtracting Fractions: Go Shopping

    ERIC Educational Resources Information Center

    Pinckard, James Seishin

    2009-01-01

    The purpose of this quasi-experimental research study was to examine the effects of an alternative or transactional algorithm for subtracting mixed numbers within the middle school setting. Initial data were gathered from the student achievement of four mathematics teachers at three different school sites. The results indicated students who…

  14. The Effects of Computer-Assisted Instruction on Student Achievement in Addition and Subtraction at First Grade Level.

    ERIC Educational Resources Information Center

    Spivey, Patsy M.

    This study was conducted to determine whether the traditional classroom approach to instruction involving the addition and subtraction of number facts (digits 0-6) is more or less effective than the traditional classroom approach plus a commercially-prepared computer game. A pretest-posttest control group design was used with two groups of first…

  15. The Effects of Computer-Assisted Instruction on Student Achievement in Addition and Subtraction at First Grade Level.

    ERIC Educational Resources Information Center

    Spivey, Patsy M.

    This study was conducted to determine whether the traditional classroom approach to instruction involving the addition and subtraction of number facts (digits 0-6) is more or less effective than the traditional classroom approach plus a commercially-prepared computer game. A pretest-posttest control group design was used with two groups of first…

  16. Angiographic CT with intravenous contrast agent application for monitoring of intracranial flow diverting stents.

    PubMed

    Saake, Marc; Struffert, Tobias; Goelitz, Philipp; Ott, Sabine; Seifert, Frank; Ganslandt, Oliver; Doerfler, Arnd

    2012-07-01

    Intracranial flow diverting devices are increasingly used to treat cerebral aneurysms. A reliable, non-invasive follow-up modality would be desirable. Our aim was to compare intra-arterial digital subtraction angiography (ia DSA) to angiographic computed tomography with intravenous contrast agent application (iv ACT) in the visualisation of flow diverting devices and aneurysm lumina. Follow-up monitoring by iv ACT (n = 36) and ia DSA (n = 25) in 14 patients treated with flow diverting devices for intracranial aneurysms was evaluated retrospectively. Images were evaluated by two neuroradiologists in anonymous consensus reading regarding the device deployment, wall apposition, neck coverage of the aneurysm, opacification of the vessel and device lumen, as well as the degree of aneurysm occlusion. Corresponding ia DSA and iv ACT images were scored identically in all patients regarding the stent deployment, wall apposition and neck coverage, as well as the degree of aneurysm occlusion and patency status of the device and parent artery. Opacification of the parent vessel lumen and perfused parts of the aneurysm was considered slightly inferior for iv ACT in comparison with ia DSA (seven of 36 cases), without impact on diagnosis. We demonstrated the feasibility and diagnostic value of iv ACT in follow-up imaging of intracranial flow diverting devices. Due to its high spatial resolution and non-invasive character, this novel technique might become a valuable imaging modality in these patients.

  17. Effect of color coding and subtraction on the accuracy of contrast echocardiography

    NASA Technical Reports Server (NTRS)

    Pasquet, A.; Greenberg, N.; Brunken, R.; Thomas, J. D.; Marwick, T. H.

    1999-01-01

    BACKGROUND: Contrast echocardiography may be used to assess myocardial perfusion. However, gray scale assessment of myocardial contrast echocardiography (MCE) is difficult because of variations in regional backscatter intensity, difficulties in distinguishing varying shades of gray, and artifacts or attenuation. We sought to determine whether the assessment of rest myocardial perfusion by MCE could be improved with subtraction and color coding. METHODS AND RESULTS: MCE was performed in 31 patients with previous myocardial infarction with a 2nd generation agent (NC100100, Nycomed AS), using harmonic triggered or continuous imaging and gain settings were kept constant throughout the study. Digitized images were post processed by subtraction of baseline from contrast data and colorized to reflect the intensity of myocardial contrast. Gray scale MCE alone, MCE images combined with baseline and subtracted colorized images were scored independently using a 16 segment model. The presence and severity of myocardial contrast abnormalities were compared with perfusion defined by rest MIBI-SPECT. Segments that were not visualized by continuous (17%) or triggered imaging (14%) after color processing were excluded from further analysis. The specificity of gray scale MCE alone (56%) or MCE combined with baseline 2D (47%) was significantly enhanced by subtraction and color coding (76%, p<0.001) of triggered images. The accuracy of the gray scale approaches (respectively 52% and 47%) was increased to 70% (p<0.001). Similarly, for continuous images, the specificity of gray scale MCE with and without baseline comparison was 23% and 42% respectively, compared with 60% after post processing (p<0.001). The accuracy of colorized images (59%) was also significantly greater than gray scale MCE (43% and 29%, p<0.001). The sensitivity of MCE for both acquisitions was not altered by subtraction. CONCLUSION: Post-processing with subtraction and color coding significantly improves the accuracy

  18. Effect of color coding and subtraction on the accuracy of contrast echocardiography

    NASA Technical Reports Server (NTRS)

    Pasquet, A.; Greenberg, N.; Brunken, R.; Thomas, J. D.; Marwick, T. H.

    1999-01-01

    BACKGROUND: Contrast echocardiography may be used to assess myocardial perfusion. However, gray scale assessment of myocardial contrast echocardiography (MCE) is difficult because of variations in regional backscatter intensity, difficulties in distinguishing varying shades of gray, and artifacts or attenuation. We sought to determine whether the assessment of rest myocardial perfusion by MCE could be improved with subtraction and color coding. METHODS AND RESULTS: MCE was performed in 31 patients with previous myocardial infarction with a 2nd generation agent (NC100100, Nycomed AS), using harmonic triggered or continuous imaging and gain settings were kept constant throughout the study. Digitized images were post processed by subtraction of baseline from contrast data and colorized to reflect the intensity of myocardial contrast. Gray scale MCE alone, MCE images combined with baseline and subtracted colorized images were scored independently using a 16 segment model. The presence and severity of myocardial contrast abnormalities were compared with perfusion defined by rest MIBI-SPECT. Segments that were not visualized by continuous (17%) or triggered imaging (14%) after color processing were excluded from further analysis. The specificity of gray scale MCE alone (56%) or MCE combined with baseline 2D (47%) was significantly enhanced by subtraction and color coding (76%, p<0.001) of triggered images. The accuracy of the gray scale approaches (respectively 52% and 47%) was increased to 70% (p<0.001). Similarly, for continuous images, the specificity of gray scale MCE with and without baseline comparison was 23% and 42% respectively, compared with 60% after post processing (p<0.001). The accuracy of colorized images (59%) was also significantly greater than gray scale MCE (43% and 29%, p<0.001). The sensitivity of MCE for both acquisitions was not altered by subtraction. CONCLUSION: Post-processing with subtraction and color coding significantly improves the accuracy

  19. Hardware Implementation of a Bilateral Subtraction Filter

    NASA Technical Reports Server (NTRS)

    Huertas, Andres; Watson, Robert; Villalpando, Carlos; Goldberg, Steven

    2009-01-01

    A bilateral subtraction filter has been implemented as a hardware module in the form of a field-programmable gate array (FPGA). In general, a bilateral subtraction filter is a key subsystem of a high-quality stereoscopic machine vision system that utilizes images that are large and/or dense. Bilateral subtraction filters have been implemented in software on general-purpose computers, but the processing speeds attainable in this way even on computers containing the fastest processors are insufficient for real-time applications. The present FPGA bilateral subtraction filter is intended to accelerate processing to real-time speed and to be a prototype of a link in a stereoscopic-machine- vision processing chain, now under development, that would process large and/or dense images in real time and would be implemented in an FPGA. In terms that are necessarily oversimplified for the sake of brevity, a bilateral subtraction filter is a smoothing, edge-preserving filter for suppressing low-frequency noise. The filter operation amounts to replacing the value for each pixel with a weighted average of the values of that pixel and the neighboring pixels in a predefined neighborhood or window (e.g., a 9 9 window). The filter weights depend partly on pixel values and partly on the window size. The present FPGA implementation of a bilateral subtraction filter utilizes a 9 9 window. This implementation was designed to take advantage of the ability to do many of the component computations in parallel pipelines to enable processing of image data at the rate at which they are generated. The filter can be considered to be divided into the following parts (see figure): a) An image pixel pipeline with a 9 9- pixel window generator, b) An array of processing elements; c) An adder tree; d) A smoothing-and-delaying unit; and e) A subtraction unit. After each 9 9 window is created, the affected pixel data are fed to the processing elements. Each processing element is fed the pixel value for

  20. Subleading power corrections for N -jettiness subtractions

    NASA Astrophysics Data System (ADS)

    Moult, Ian; Rothen, Lorena; Stewart, Iain W.; Tackmann, Frank J.; Zhu, Hua Xing

    2017-04-01

    The N -jettiness observable TN provides a way of describing the leading singular behavior of the N -jet cross section in the τ =TN/Q →0 limit, where Q is a hard interaction scale. We consider subleading-power corrections in the τ ≪1 expansion, and employ soft-collinear effective theory to obtain analytic results for the dominant αsτ ln τ and αs2τ ln3τ subleading terms for thrust in e+e- collisions and 0-jettiness for q q ¯-initiated Drell-Yan-like processes at hadron colliders. These results can be used to significantly improve the numerical accuracy and stability of the N -jettiness subtraction technique for performing fixed-order calculations at next-to-leading order and next-to-next-to-leading order. They reduce the size of missing power corrections in the subtractions by an order of magnitude. We also point out that the precise definition of N -jettiness has an important impact on the size of the power corrections and thus the numerical accuracy of the subtractions. The sometimes employed definition of N -jettiness in the hadronic center-of-mass frame suffers from power corrections that grow exponentially with rapidity, causing the power expansion to deteriorate away from central rapidity. This degradation does not occur for the original N -jettiness definition, which explicitly accounts for the boost of the Born process relative to the frame of the hadronic collision, and has a well-behaved power expansion throughout the entire phase space. Integrated over rapidity, using this N -jettiness definition in the subtractions yields another order of magnitude improvement compared to employing the hadronic-frame definition.

  1. Sky Subtraction with Fiber-Fed Spectrograph

    NASA Astrophysics Data System (ADS)

    Rodrigues, Myriam

    2017-09-01

    "Historically, fiber-fed spectrographs had been deemed inadequate for the observation of faint targets, mainly because of the difficulty to achieve high accuracy on the sky subtraction. The impossibility to sample the sky in the immediate vicinity of the target in fiber instruments has led to a commonly held view that a multi-object fibre spectrograph cannot achieve an accurate sky subtraction under 1% contrary to their slit counterpart. The next generation of multi-objects spectrograph at the VLT (MOONS) and the planed MOS for the E-ELT (MOSAIC) are fiber-fed instruments, and are aimed to observed targets fainter than the sky continuum level. In this talk, I will present the state-of-art on sky subtraction strategies and data reduction algorithm specifically developed for fiber-fed spectrographs. I will also present the main results of an observational campaign to better characterise the sky spatial and temporal variations ( in particular the continuum and faint sky lines)."

  2. Subtractive Structural Modification of Morpho Butterfly Wings.

    PubMed

    Shen, Qingchen; He, Jiaqing; Ni, Mengtian; Song, Chengyi; Zhou, Lingye; Hu, Hang; Zhang, Ruoxi; Luo, Zhen; Wang, Ge; Tao, Peng; Deng, Tao; Shang, Wen

    2015-11-11

    Different from studies of butterfly wings through additive modification, this work for the first time studies the property change of butterfly wings through subtractive modification using oxygen plasma etching. The controlled modification of butterfly wings through such subtractive process results in gradual change of the optical properties, and helps the further understanding of structural optimization through natural evolution. The brilliant color of Morpho butterfly wings is originated from the hierarchical nanostructure on the wing scales. Such nanoarchitecture has attracted a lot of research effort, including the study of its optical properties, its potential use in sensing and infrared imaging, and also the use of such structure as template for the fabrication of high-performance photocatalytic materials. The controlled subtractive processes provide a new path to modify such nanoarchitecture and its optical property. Distinct from previous studies on the optical property of the Morpho wing structure, this study provides additional experimental evidence for the origination of the optical property of the natural butterfly wing scales. The study also offers a facile approach to generate new 3D nanostructures using butterfly wings as the templates and may lead to simpler structure models for large-scale man-made structures than those offered by original butterfly wings. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. An Experimental Implementation of Chemical Subtraction

    PubMed Central

    Chen, Shao-Nong; Turner, Allison; Jaki, Birgit U.; Nikolic, Dejan; van Breemen, Richard B.; Friesen, J. Brent; Pauli, Guido F.

    2008-01-01

    A preparative analytical method was developed to selectively remove (“chemically subtract”) a single compound from a complex mixture, such as a natural extract or fraction, in a single step. The proof of concept is demonstrated by the removal of pure benzoic acid (BA) from cranberry (Vaccinium macrocarpon Ait.) juice fractions that exhibit anti-adhesive effects vs. uropathogenic E. coli. Chemical subtraction of BA, representing a major constituent of the fractions, eliminates the potential in vitro interference of the bacteriostatic effect of BA on the E. coli anti-adherence action measured in bioassays. Upon BA removal, the anti-adherent activity of the fraction was fully retained, 36% inhibition of adherence in the parent fraction at 100 ug/mL increased to 58% in the BA-free active fraction. The method employs countercurrent chromatography (CCC) and operates loss-free for both the subtracted and the retained portions as only liquid-liquid partitioning is involved. While the high purity (97.47% by quantitative 1H NMR) of the subtracted BA confirms the selectivity of the method, one minor impurity was determined to be scopoletin by HR-ESI-MS and (q)HNMR and represents the first coumarin reported from cranberries. A general concept for the selective removal of phytoconstituents by CCC is presented, which has potential broad applicability in the biological evaluation of medicinal plant extracts and complex pharmaceutical preparations. PMID:18234463

  4. Ambient-Light-Canceling Camera Using Subtraction of Frames

    NASA Technical Reports Server (NTRS)

    Morookian, John Michael

    2004-01-01

    The ambient-light-canceling camera (ALCC) is a proposed near-infrared electronic camera that would utilize a combination of (1) synchronized illumination during alternate frame periods and (2) subtraction of readouts from consecutive frames to obtain images without a background component of ambient light. The ALCC is intended especially for use in tracking the motion of an eye by the pupil center corneal reflection (PCCR) method. Eye tracking by the PCCR method has shown potential for application in human-computer interaction for people with and without disabilities, and for noninvasive monitoring, detection, and even diagnosis of physiological and neurological deficiencies. In the PCCR method, an eye is illuminated by near-infrared light from a lightemitting diode (LED). Some of the infrared light is reflected from the surface of the cornea. Some of the infrared light enters the eye through the pupil and is reflected from back of the eye out through the pupil a phenomenon commonly observed as the red-eye effect in flash photography. An electronic camera is oriented to image the user's eye. The output of the camera is digitized and processed by algorithms that locate the two reflections. Then from the locations of the centers of the two reflections, the direction of gaze is computed. As described thus far, the PCCR method is susceptible to errors caused by reflections of ambient light. Although a near-infrared band-pass optical filter can be used to discriminate against ambient light, some sources of ambient light have enough in-band power to compete with the LED signal. The mode of operation of the ALCC would complement or supplant spectral filtering by providing more nearly complete cancellation of the effect of ambient light. In the operation of the ALCC, a near-infrared LED would be pulsed on during one camera frame period and off during the next frame period. Thus, the scene would be illuminated by both the LED (signal) light and the ambient (background) light

  5. A comparative study of additive and subtractive manufacturing for dental restorations.

    PubMed

    Bae, Eun-Jeong; Jeong, Il-Do; Kim, Woong-Chul; Kim, Ji-Hwan

    2017-08-01

    Digital systems have recently found widespread application in the fabrication of dental restorations. For the clinical assessment of dental restorations fabricated digitally, it is necessary to evaluate their accuracy. However, studies of the accuracy of inlay restorations fabricated with additive manufacturing are lacking. The purpose of this in vitro study was to evaluate and compare the accuracy of inlay restorations fabricated by using recently introduced additive manufacturing with the accuracy of subtractive methods. The inlay (distal occlusal cavity) shape was fabricated using 3-dimensional image (reference data) software. Specimens were fabricated using 4 different methods (each n=10, total N=40), including 2 additive manufacturing methods, stereolithography apparatus and selective laser sintering; and 2 subtractive methods, wax and zirconia milling. Fabricated specimens were scanned using a dental scanner and then compared by overlapping reference data. The results were statistically analyzed using a 1-way analysis of variance (α=.05). Additionally, the surface morphology of 1 randomly (the first of each specimen) selected specimen from each group was evaluated using a digital microscope. The results of the overlap analysis of the dental restorations indicated that the root mean square (RMS) deviation observed in the restorations fabricated using the additive manufacturing methods were significantly different from those fabricated using the subtractive methods (P<.05). However, no significant differences were found between restorations fabricated using stereolithography apparatus and selective laser sintering, the additive manufacturing methods (P=.466). Similarly, no significant differences were found between wax and zirconia, the subtractive methods (P=.986). The observed RMS values were 106 μm for stereolithography apparatus, 113 μm for selective laser sintering, 116 μm for wax, and 119 μm for zirconia. Microscopic evaluation of the surface

  6. Intravenous clonazepam in eclampsia.

    PubMed

    Harding, D L; Leong, C M

    1988-02-01

    A case of postpartum eclampsia is reported, controlled by intravenous clonazepam, a benzodiazepine anticonvulsant. Clonazepam was effective in controlling the myoclonic jerks, which were a feature in this patient, without producing excessive sedation. The literature reveals several reports on the use of clonazepam in severe preeclampsia, but its use in Australia has not been widely employed.

  7. Aluminum plasmonics based highly transmissive polarization-independent subtractive color filters exploiting a nanopatch array.

    PubMed

    Shrestha, Vivek R; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong

    2014-11-12

    Nanophotonic devices enabled by aluminum plasmonics are saliently advantageous in terms of their low cost, outstanding sustainability, and affordable volume production. We report, for the first time, aluminum plasmonics based highly transmissive polarization-independent subtractive color filters, which are fabricated just with single step electron-beam lithography. The filters feature selective suppression in the transmission spectra, which is realized by combining the propagating and nonpropagating surface plasmons mediated by an array of opaque and physically thin aluminum nanopatches. A broad palette of bright, high-contrast subtractive colors is successfully demonstrated by simply varying the pitches of the nanopatches. These subtractive color filters have twice the photon throughput of additive counterparts, ultimately providing elevated optical transmission and thus stronger color signals. Moreover, the filters are demonstrated to conspicuously feature a dual-mode operation, both transmissive and reflective, in conjunction with a capability to exhibit micron-scale colors in arbitrary shapes. They are anticipated to be diversely applied to digital display, digital imaging, color printing, and sensing.

  8. Dynamic powerline interference subtraction from biosignals.

    PubMed

    Christov, I I

    2000-01-01

    The performance of a previously developed and widely used method for powerline interference subtraction from the ECG is slightly reduced in the presence of continuous well-expressed EMG noise. Applying automatic adaptation of the 'linearity criterion' value in accordance to the ECG/noise ratio, the best conditions for application of the procedure can be obtained. The proposed method allows for reduction of possible distortions when applied on noise-free ECG and enhances its efficiency in the presence of non-powerline noise. Apart from ECG, it is applicable to impedance-cardiogram, plethysmogram, EEG and other biosignals.

  9. Binary Classification and the Subtractive Approach.

    DTIC Science & Technology

    1983-09-01

    AR[l 1,t AFAMRL-TR-83-050 BINARY CLASSIFICATION AND THE SUBTRACTIVE APPROACH Gregory M. Corso Georgia Institute of Technology Suzanne Kelly 9 Danny E...GRANT NUMBER(O) Gregory M. Corso * F49620-82-C-0035 Suzanne Kelly Danny E. Bridges, TSgt, USAF 9 PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM...A NA3 1 BINARY CLASSIFICATION AND THE SABTRACTIVE APPROACH(A) 1/1 EDUCATION INC ST CLOUD FL G M CORSO ET AL. SEP 83 UNCLASSIFIED AFAMRL-T 83 050

  10. Subtraction procedure for powerline interference removing from ECG: improvement for non-multiple sampling.

    PubMed

    Mihov, G; Dotsinsky, I V; Georgieva, T S

    2005-01-01

    This paper presents an improvement of the subtraction procedure for interference cancellation in ECG. In contrast to the well-known hardware and software filters, the procedure does not affect the signal frequency components around the rated powerline frequency. Originally, the procedure was developed for multiplicity between the sampling rate and the interference frequency. We analysed and improved the procedure structure in cases of non-multiple sampling, introducing a set of specially designed filters. Thus the implementation of the subtraction procedure is extended to almost all possible cases of sampling rate and interference frequency variation. The procedure has been adapted for online implementation. The research was initially carried out in a MATLAB environment. Further, programmes have been written in C( + +) language for digital signal processors and personal computers. The results obtained with real ECG signals show high efficiency of the interference cancellation.

  11. Additive and subtractive transparent depth displays

    NASA Astrophysics Data System (ADS)

    Kooi, Frank L.; Toet, Alexander

    2003-09-01

    Image fusion is the generally preferred method to combine two or more images for visual display on a single screen. We demonstrate that perceptual image separation may be preferable over perceptual image fusion for the combined display of enhanced and synthetic imagery. In this context image separation refers to the simultaneous presentation of images on different depth planes of a single display. Image separation allows the user to recognize the source of the information that is displayed. This can be important because synthetic images are more liable to flaws. We have examined methods to optimize perceptual image separation. A true depth difference between enhanced and synthetic imagery works quite well. A standard stereoscopic display based on convergence is less suitable since the two images tend to interfere: the image behind is masked (occluded) by the image in front, which results in poor viewing comfort. This effect places 3D systems based on 3D glasses, as well as most autostereoscopic displays, at a serious disadvantage. A 3D display based on additive or subtractive transparency is acceptable: both the perceptual separation and the viewing comfort are good, but the color of objects depends on the color in the other depth layer(s). A combined additive and subtractive transparent display eliminates this disadvantage and is most suitable for the combined display of enhanced and synthetic imagery. We suggest that the development of such a display system is of a greater practical value than increasing the number of depth planes in autostereoscopic displays.

  12. A Mathematical Model for Suppression Subtractive Hybridization

    PubMed Central

    Gadgil, Chetan; Rink, Anette; Beattie, Craig

    2002-01-01

    Suppression subtractive hybridization (SSH) is frequently used to unearth differentially expressed genes on a whole-genome scale. Its versatility is based on combining cDNA library subtraction and normalization, which allows the isolation of sequences of varying degrees of abundance and differential expression. SSH is a complex process with many adjustable parameters that affect the outcome of gene isolation.We present a mathematical model of SSH based on DNA hybridization kinetics for assessing the effect of various parameters to facilitate its optimization. We derive an equation for the probability that a particular differentially expressed species is successfully isolated and use this to quantify the effect of the following parameters related to the cDNA sample: (a) mRNA abundance; (b) partial sequence complementarity to other species; and (3) degree of differential expression. We also evaluate the effect of parameters related to the process, including: (a) reaction times; and (b) extent of driver excess used in the two hybridization reactions. The optimum set of process parameters for successful isolation of differentially expressed species depends on transcript abundance. We show that the reaction conditions have a significant effect on the occurrence of false-positives and formulate strategies to isolate specific subsets of differentially expressed genes. We also quantify the effect of non-specific hybridization on the false-positive results and present strategies for spiking cDNA sequences to address this problem. PMID:18629052

  13. Children's understanding of addition and subtraction concepts.

    PubMed

    Robinson, Katherine M; Dubé, Adam K

    2009-08-01

    After the onset of formal schooling, little is known about the development of children's understanding of the arithmetic concepts of inversion and associativity. On problems of the form a+b-b (e.g., 3+26-26), if children understand the inversion concept (i.e., that addition and subtraction are inverse operations), then no calculations are needed to solve the problem. On problems of the form a+b-c (e.g., 3+27-23), if children understand the associativity concept (i.e., that the addition and subtraction can be solved in any order), then the second part of the problem can be solved first. Children in Grades 2, 3, and 4 solved both types of problems and then were given a demonstration of how to apply both concepts. Approval of each concept and preference of a conceptual approach versus an algorithmic approach were measured. Few grade differences were found on either task. Conceptual understanding was greater for inversion than for associativity on both tasks. Clusters of participants in all grades showed that some had strong understanding of both concepts, some had strong understanding of the inversion concept only, and others had weak understanding of both concepts. The findings highlight the lack of developmental increases and the large individual differences in conceptual understanding on two arithmetic concepts during the early school years.

  14. Astronomical Image Subtraction by Cross-Convolution

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Akerlof, Carl W.

    2008-04-01

    In recent years, there has been a proliferation of wide-field sky surveys to search for a variety of transient objects. Using relatively short focal lengths, the optics of these systems produce undersampled stellar images often marred by a variety of aberrations. As participants in such activities, we have developed a new algorithm for image subtraction that no longer requires high-quality reference images for comparison. The computational efficiency is comparable with similar procedures currently in use. The general technique is cross-convolution: two convolution kernels are generated to make a test image and a reference image separately transform to match as closely as possible. In analogy to the optimization technique for generating smoothing splines, the inclusion of an rms width penalty term constrains the diffusion of stellar images. In addition, by evaluating the convolution kernels on uniformly spaced subimages across the total area, these routines can accommodate point-spread functions that vary considerably across the focal plane.

  15. Community intravenous therapy provision.

    PubMed

    O'Hanlon, Sue; McGrail, Pam; Hodgkins, Paul

    2017-03-08

    Many healthcare services that were once only available in acute settings are now common in the community. Intravenous (IV) therapy is increasingly available as a community service. Given the option, most patients would choose to receive their treatment in a community setting, rather than in hospital. This article describes several outpatient parenteral antimicrobial therapy services, including their advantages and disadvantages. It explores the ways one community NHS trust has developed its community IV therapy service over the past ten years and examines issues pertinent to effective service delivery.

  16. Flat-detector computed tomography with intravenous contrast material application in experimental aneurysms: comparison with multislice CT and conventional angiography.

    PubMed

    Struffert, Tobias; Doelken, Marc; Adamek, Edyta; Schwarz, Marc; Engelhorn, Tobias; Kloska, Stephan; Ott, Sabine; Doerfler, Arnd

    2010-05-01

    Despite limited soft tissue resolution flat-detector computed tomography (FD-CT) provides substantial superior spatial resolution in comparison with multislice computed tomography (MS-CT). This may add value in the visualization of small vascular structures if intravenous contrast application leads to substantial opacification and visibility of intracranial vessels or aneurysms. To evaluate the feasibility of visualization of vascular structures by FD-CT angiography (FD-CTA) after intravenous contrast injection compared with MS-CTA and intra-arterial digital subtracted angiography (IADSA) in an animal model. Aneurysms were created in the right common carotid artery in six New Zealand White Rabbits using the elastase technique. Imaging was performed using FD-CTA, MS-CTA (injection of 1 ml/kg body weight) and IADSA. Anonymized volume rendering reconstruction (VRT), maximum intensity projection (MIP), and multiplanar reconstruction (MPR) images were reconstructed and evaluated by two experienced reviewers for aneurysm geometry and vascular structure anatomy using standard tools of a dedicated workstation. Aneurysms could be successfully created in all animals. Measurements of aneurysm geometry (aneurysm height, width, neck width) and vascular structures (brachiocephalic trunk, carotid artery diameter and plane) were nearly identical in all three modalities. Intra- and inter-observer correlations of the different parameters showed high r values between 0.83 and 0.99. Our results show the feasibility of FD-CTA in comparison with MS-CTA and IADSA in an animal model. Despite limited soft tissue resolution, opacification of vascular structures with sufficient contrast to the surrounding structures was possible in all animals. Vascular structures appeared better delineated in FD-CTA than in MS-CTA, probably due to the superior spatial resolution.

  17. Renormalization of quark bilinear operators in a momentum-subtraction scheme with a nonexceptional subtraction point

    SciTech Connect

    Sturm, C.; Soni, A.; Aoki, Y.; Christ, N. H.; Izubuchi, T.; Sachrajda, C. T. C.

    2009-07-01

    We extend the Rome-Southampton regularization independent momentum-subtraction renormalization scheme (RI/MOM) for bilinear operators to one with a nonexceptional, symmetric subtraction point. Two-point Green's functions with the insertion of quark bilinear operators are computed with scalar, pseudoscalar, vector, axial-vector and tensor operators at one-loop order in perturbative QCD. We call this new scheme RI/SMOM, where the S stands for 'symmetric'. Conversion factors are derived, which connect the RI/SMOM scheme and the MS scheme and can be used to convert results obtained in lattice calculations into the MS scheme. Such a symmetric subtraction point involves nonexceptional momenta implying a lattice calculation with substantially suppressed contamination from infrared effects. Further, we find that the size of the one-loop corrections for these infrared improved kinematics is substantially decreased in the case of the pseudoscalar and scalar operator, suggesting a much better behaved perturbative series. Therefore it should allow us to reduce the error in the determination of the quark mass appreciably.

  18. Evolutionary Processes in the Development of Errors in Subtraction Algorithms

    ERIC Educational Resources Information Center

    Fernandez, Ricardo Lopez; Garcia, Ana B. Sanchez

    2008-01-01

    The study of errors made in subtraction is a research subject approached from different theoretical premises that affect different components of the algorithmic process as triggers of their generation. In the following research an attempt has been made to investigate the typology and nature of errors which occur in subtractions and their evolution…

  19. A Proposed Instructional Theory for Integer Addition and Subtraction

    ERIC Educational Resources Information Center

    Stephan, Michelle; Akyuz, Didem

    2012-01-01

    This article presents the results of a 7th-grade classroom teaching experiment that supported students' understanding of integer addition and subtraction. The experiment was conducted to test and revise a hypothetical learning trajectory so as to propose a potential instructional theory for integer addition and subtraction. The instructional…

  20. Developing a Model to Support Students in Solving Subtraction

    ERIC Educational Resources Information Center

    Murdiyani, Nila Mareta; Zulkardi; Putri, Ratu Ilma Indra; van Eerde, Dolly; van Galen, Frans

    2013-01-01

    Subtraction has two meanings and each meaning leads to the different strategies. The meaning of "taking away something" suggests a direct subtraction, while the meaning of "determining the difference between two numbers" is more likely to be modeled as indirect addition. Many prior researches found that the second meaning and…

  1. Evolutionary Processes in the Development of Errors in Subtraction Algorithms

    ERIC Educational Resources Information Center

    Fernandez, Ricardo Lopez; Garcia, Ana B. Sanchez

    2008-01-01

    The study of errors made in subtraction is a research subject approached from different theoretical premises that affect different components of the algorithmic process as triggers of their generation. In the following research an attempt has been made to investigate the typology and nature of errors which occur in subtractions and their evolution…

  2. Intravenous fluids: balancing solutions.

    PubMed

    Hoorn, Ewout J

    2017-08-01

    The topic of intravenous (IV) fluids may be regarded as "reverse nephrology", because nephrologists usually treat to remove fluids rather than to infuse them. However, because nephrology is deeply rooted in fluid, electrolyte, and acid-base balance, IV fluids belong in the realm of our specialty. The field of IV fluid therapy is in motion due to the increasing use of balanced crystalloids, partly fueled by the advent of new solutions. This review aims to capture these recent developments by critically evaluating the current evidence base. It will review both indications and complications of IV fluid therapy, including the characteristics of the currently available solutions. It will also cover the use of IV fluids in specific settings such as kidney transplantation and pediatrics. Finally, this review will address the pathogenesis of saline-induced hyperchloremic acidosis, its potential effect on outcomes, and the question if this should lead to a definitive switch to balanced solutions.

  3. Intravenous Fluid Generation System

    NASA Technical Reports Server (NTRS)

    McQuillen, John; McKay, Terri; Brown, Daniel; Zoldak, John

    2013-01-01

    The ability to stabilize and treat patients on exploration missions will depend on access to needed consumables. Intravenous (IV) fluids have been identified as required consumables. A review of the Space Medicine Exploration Medical Condition List (SMEMCL) lists over 400 medical conditions that could present and require treatment during ISS missions. The Intravenous Fluid Generation System (IVGEN) technology provides the scalable capability to generate IV fluids from indigenous water supplies. It meets USP (U.S. Pharmacopeia) standards. This capability was performed using potable water from the ISS; water from more extreme environments would need preconditioning. The key advantage is the ability to filter mass and volume, providing the equivalent amount of IV fluid: this is critical for remote operations or resource- poor environments. The IVGEN technology purifies drinking water, mixes it with salt, and transfers it to a suitable bag to deliver a sterile normal saline solution. Operational constraints such as mass limitations and lack of refrigeration may limit the type and volume of such fluids that can be carried onboard the spacecraft. In addition, most medical fluids have a shelf life that is shorter than some mission durations. Consequently, the objective of the IVGEN experiment was to develop, design, and validate the necessary methodology to purify spacecraft potable water into a normal saline solution, thus reducing the amount of IV fluids that are included in the launch manifest. As currently conceived, an IVGEN system for a space exploration mission would consist of an accumulator, a purifier, a mixing assembly, a salt bag, and a sterile bag. The accumulator is used to transfer a measured amount of drinking water from the spacecraft to the purifier. The purifier uses filters to separate any air bubbles that may have gotten trapped during the drinking water transfer from flowing through a high-quality deionizing cartridge that removes the impurities in

  4. Digitized synchronous demodulator

    NASA Technical Reports Server (NTRS)

    Woodhouse, Christopher E. (Inventor)

    1990-01-01

    A digitized synchronous demodulator is constructed entirely of digital components including timing logic, an accumulator, and means to digitally filter the digital output signal. Indirectly, it accepts, at its input, periodic analog signals which are converted to digital signals by traditional analog-to-digital conversion techniques. Broadly, the input digital signals are summed to one of two registers within an accumulator, based on the phase of the input signal and medicated by timing logic. At the end of a predetermined number of cycles of the inputted periodic signals, the contents of the register that accumulated samples from the negative half cycle is subtracted from the accumulated samples from the positive half cycle. The resulting difference is an accurate measurement of the narrow band amplitude of the periodic input signal during the measurement period. This measurement will not include error sources encountered in prior art synchronous demodulators using analog techniques such as offsets, charge injection errors, temperature drift, switching transients, settling time, analog to digital converter missing code, and linearity errors.

  5. Taking Away and Determining the Difference--A Longitudinal Perspective on Two Models of Subtraction and the Inverse Relation to Addition

    ERIC Educational Resources Information Center

    Selter, Christoph; Prediger, Susanne; Nuhrenborger, Marcus; Hussmann, Stephan

    2012-01-01

    Subtraction can be understood by two basic models--taking away (ta) and determining the difference (dd)--and by its inverse relation to addition. Epistemological analyses and empirical examples show that the two models are not relevant only in single-digit arithmetic. As curricula should be developed in a longitudinal perspective on mathematics…

  6. Accessing the diffracted wavefield by coherent subtraction

    NASA Astrophysics Data System (ADS)

    Schwarz, Benjamin; Gajewski, Dirk

    2017-10-01

    Diffractions have unique properties which are still rarely exploited in common practice. Aside from containing subwavelength information on the scattering geometry or indicating small-scale structural complexity, they provide superior illumination compared to reflections. While diffraction occurs arguably on all scales and in most realistic media, the respective signatures typically have low amplitudes and are likely to be masked by more prominent wavefield components. It has been widely observed that automated stacking acts as a directional filter favouring the most coherent arrivals. In contrast to other works, which commonly aim at steering the summation operator towards fainter contributions, we utilize this directional selection to coherently approximate the most dominant arrivals and subtract them from the data. Supported by additional filter functions which can be derived from wave front attributes gained during the stacking procedure, this strategy allows for a fully data-driven recovery of faint diffractions and makes them accessible for further processing. A complex single-channel field data example recorded in the Aegean sea near Santorini illustrates that the diffracted background wavefield is surprisingly rich and despite the absence of a high channel count can still be detected and characterized, suggesting a variety of applications in industry and academia.

  7. Optimized angiographic computed tomography with intravenous contrast injection: an alternative to conventional angiography in the follow-up of clipped aneurysms?

    PubMed

    Gölitz, Philipp; Struffert, Tobias; Ganslandt, Oliver; Saake, Marc; Lücking, Hannes; Rösch, Julie; Knossalla, Frauke; Doerfler, Arnd

    2012-07-01

    The purpose of this study was to evaluate the diagnostic accuracy of an optimized angiographic CT (ACT) program with intravenous contrast agent injection (ivACT) in the assessment of potential aneurysm remnants after neurosurgical clipping compared with conventional digital subtraction angiography (DSA). The authors report on 14 patients with 19 surgically clipped cerebral aneurysms who were scheduled to undergo angiographic follow-up. For each patient, the authors performed ivACT with dual rotational acquisition and conventional angiography including a 3D rotational run. The ivACT and 3D DSA data were reconstructed with different imaging modes, including a newly implemented subtraction mode with motion correction. Thereafter, the data sets were merged by the dual-volume technique, and freely rotatable 3D images were obtained for further analysis. Observed aneurysm remnants were electronically measured and classified for each modality by 2 experienced neuroradiologists. Digital subtraction angiography and ivACT both provided high-quality images without motion artifacts. Artifact disturbances from the aneurysm clips led to a compromised, but still sufficient, image quality in 1 case. The ivACT assessed all aneurysm remnants as true-positive up to a minimal size of 2.6×2.4 mm in accordance with the DSA findings. There was a tendency for ivACT to overestimate the size of the aneurysm remnants. All cases without aneurysm remnants on DSA were scored correctly as true-negative by ivACT. By using an optimized image acquisition protocol as well as enhanced postprocessing algorithms, the noninvasive ivACT seems to achieve results comparable to those of conventional angiography in the follow-up of clipped cerebral aneurysms. The authors have shown that ivACT can provide reliable diagnostic information about potential aneurysm remnants after neurosurgical clipping with high sensitivity and specificity, sufficient for clinical decision making, at least for aneurysms in the

  8. Prokaryotic suppression subtractive hybridization PCR cDNA subtraction, a targeted method to identify differentially expressed genes.

    PubMed

    De Long, Susan K; Kinney, Kerry A; Kirisits, Mary Jo

    2008-01-01

    Molecular biology tools can be used to monitor and optimize biological treatment systems, but the application of nucleic acid-based tools has been hindered by the lack of available sequences for environmentally relevant biodegradation genes. The objective of our work was to extend an existing molecular method for eukaryotes to prokaryotes, allowing us to rapidly identify differentially expressed genes for subsequent sequencing. Suppression subtractive hybridization (SSH) PCR cDNA subtraction is a technique that can be used to identify genes that are expressed under specific conditions (e.g., growth on a given pollutant). While excellent methods for eukaryotic SSH PCR cDNA subtraction are available, to our knowledge, no methods previously existed for prokaryotes. This work describes our methodology for prokaryotic SSH PCR cDNA subtraction, which we validated using a model system: Pseudomonas putida mt-2 degrading toluene. cDNA from P. putida mt-2 grown on toluene (model pollutant) or acetate (control substrate) was subjected to our prokaryotic SSH PCR cDNA subtraction protocol to generate subtraction clone libraries. Over 90% of the sequenced clones contained gene fragments encoding toluene-related enzymes, and 20 distinct toluene-related genes from three key operons were sequenced. Based on these results, prokaryotic SSH PCR cDNA subtraction shows promise as a targeted method for gene identification.

  9. Soft-collinear factorization and zero-bin subtractions

    SciTech Connect

    Chiu Juiyu; Fuhrer, Andreas; Kelley, Randall; Manohar, Aneesh V.; Hoang, Andre H.

    2009-03-01

    We study the Sudakov form factor for a spontaneously broken gauge theory using a (new) {delta}-regulator. To be well defined, the effective theory requires zero-bin subtractions for the collinear sectors. The zero-bin subtractions depend on the gauge boson mass M and are not scaleless. They have both finite and 1/{epsilon} contributions and are needed to give the correct anomalous dimension and low-scale matching contributions. We also demonstrate the necessity of zero-bin subtractions for soft-collinear factorization. We find that after zero-bin subtractions the form factor is the sum of the collinear contributions minus a soft mass-mode contribution, in agreement with a previous result of Idilbi and Mehen in QCD. This appears to conflict with the method-of-regions approach, where one gets the sum of contributions from different regions.

  10. Improvements in floating point addition/subtraction operations

    DOEpatents

    Farmwald, P.M.

    1984-02-24

    Apparatus is described for decreasing the latency time associated with floating point addition and subtraction in a computer, using a novel bifurcated, pre-normalization/post-normalization approach that distinguishes between differences of floating point exponents.

  11. Advanced Background Subtraction Applied to Aeroacoustic Wind Tunnel Testing

    NASA Technical Reports Server (NTRS)

    Bahr, Christopher J.; Horne, William C.

    2015-01-01

    An advanced form of background subtraction is presented and applied to aeroacoustic wind tunnel data. A variant of this method has seen use in other fields such as climatology and medical imaging. The technique, based on an eigenvalue decomposition of the background noise cross-spectral matrix, is robust against situations where isolated background auto-spectral levels are measured to be higher than levels of combined source and background signals. It also provides an alternate estimate of the cross-spectrum, which previously might have poor definition for low signal-to-noise ratio measurements. Simulated results indicate similar performance to conventional background subtraction when the subtracted spectra are weaker than the true contaminating background levels. Superior performance is observed when the subtracted spectra are stronger than the true contaminating background levels. Experimental results show limited success in recovering signal behavior for data where conventional background subtraction fails. They also demonstrate the new subtraction technique's ability to maintain a proper coherence relationship in the modified cross-spectral matrix. Beam-forming and de-convolution results indicate the method can successfully separate sources. Results also show a reduced need for the use of diagonal removal in phased array processing, at least for the limited data sets considered.

  12. Digital computer processing of X-ray photos

    NASA Technical Reports Server (NTRS)

    Nathan, R.; Selzer, R. H.

    1967-01-01

    Digital computers correct various distortions in medical and biological photographs. One of the principal methods of computer enhancement involves the use of a two-dimensional digital filter to modify the frequency spectrum of the picture. Another computer processing method is image subtraction.

  13. Comparison of iodine K-edge subtraction and fluorescence subtraction imaging in an animal system

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Zhu, Y.; Bewer, B.; Zhang, L.; Korbas, M.; Pickering, I. J.; George, G. N.; Gupta, M.; Chapman, D.

    2008-09-01

    K-Edge Subtraction (KES) utilizes the discontinuity in the X-ray absorption across the absorption edge of the selected contrast element and creates an image of the projected density of the contrast element from two images acquired just above and below the K-edge of the contrast element. KES has proved to be powerful in coronary angiography, micro-angiography, bronchography, and lymphatic imaging. X-ray fluorescence imaging is a successful technique for the detection of dilute quantities of elements in specimens. However, its application at high X-ray energies (e.g. at the iodine K-edge) is complicated by significant Compton background, which may enter the energy window set for the contrast material's fluorescent X-rays. Inspired by KES, Fluorescence Subtraction Imaging (FSI) is a technique for high-energy (>20 keV) fluorescence imaging using two different incident beam energies just above and below the absorption edge of a contrast element (e.g. iodine). The below-edge image can be assumed as a "background" image, which includes Compton scatter and fluorescence from other elements. The above-edge image will contain nearly identical spectral content as the below-edge image but will contain the additional fluorescence of the contrast element. This imaging method is especially promising with thick objects with dilute contrast materials, significant Compton background, and/or competing fluorescence lines from other materials. A quality factor is developed to facilitate the comparison. The theoretical value of the quality factor sets the upper limit that an imaging method can achieve when the noise is Poisson limited. The measured value of this factor makes two or more imaging methods comparable. Using the Hard X-ray Micro-Analysis (HXMA) beamline at the Canadian Light Source (CLS), the techniques of FSI and KES were critically compared, with reference to radiation dose, image acquisition time, resolution, signal-to-noise ratios, and quality factor.

  14. Targeted Gold Nanoparticle Contrast Agent for Digital Breast Tomosynthesis and Computed Tomography

    DTIC Science & Technology

    2010-03-01

    TITLE: Targeted Gold Nanoparticle Contrast Agent for Digital Breast Tomosynthesis and Computed Tomography PRINCIPAL INVESTIGATOR: Roshan...2009 – Feb 14, 2010 4. TITLE AND SUBTITLE Targeted Gold Nanoparticle Contrast Agent for Digital Breast 5a. CONTRACT NUMBER Tomosynthesis and...of all breast cancers [2, 3]. The combination of such contrast agents with temporal subtraction breast tomosynthesis (DBT) or digital mammography

  15. Embossed radiography utilizing an image-shifting subtraction program

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Osawa, Akihiro; Matsukiyo, Hiroshi; Enomoto, Toshiyuki; Watanabe, Manabu; Takahashi, Kiyomi; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2010-07-01

    We developed an image-shifting subtraction program and carried out embossed radiography (ER) utilizing single- and dual-energy subtractions. In particular, dual-energy subtraction was carried out to decrease the absorption contrast of unnecessary regions. The contrast resolution of a target region was increased using the subtraction program and a linear-contrast system in a flat panel detector (FPD). The X-ray generator had a 100 μm-focus tube, and the subtractions were performed at tube voltages of 40 and 70 kV, a tube current of 0.50 mA, and an X-ray exposure time of 5.0 s. ER was achieved with cohesion imaging using the FPD with pixel sizes of 48×48 μm 2, and the shifting dimension of an object in the horizontal and vertical directions ranged from 48 to 96 μm. At a shifting distance of 96 μm, the spatial resolutions in the horizontal and vertical directions measured with a lead test chart were both 83 μm. In ER of animal phantoms, we obtained high-contrast embossed images of fine bones, gadolinium oxide particles in blood vessels, iodine-based microspheres in coronary arteries approximately 100 μm in diameter.

  16. Magnification Embossed Radiography Utilizing Image-Shifting Subtraction Program

    NASA Astrophysics Data System (ADS)

    Osawa, Akihiro; Watanabe, Manabu; Sato, Eiichi; Matsukiyo, Hiroshi; Enomoto, Toshiyuki; Nagao, Jiro; Abderyim, Purkhet; Aizawa, Katsuo; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Ogawa, Akira; Takahashi, Kiyomi; Sato, Shigehiro; Onagawa, Jun

    2010-03-01

    We developed an image-shifting subtraction program and carried out magnification embossed radiography (MER) utilizing single- and dual-energy subtractions. In particular, dual-energy subtraction was carried out to decrease the absorption contrast of unnecessary regions. The contrast resolution of the target region was increased by the use of subtraction software and a linear-contrast system in a flat-panel detector (FPD). The X-ray generator had a 100-µm-focus tube, and the subtractions were performed at tube voltages of 40 and 70 kV, a tube current of 0.50 mA, and an X-ray exposure time of 5.0 s. MER images with threefold magnification were obtained using the FPD with a pixel size of 48×48 µm2, and the shifting dimensions of the imaged object in the horizontal and vertical directions ranged from 48 to 192 µm. At a shifting distance ranging from 48 to 144 µm, the spatial resolutions in the horizontal and vertical directions measured with a lead test chart were both 50 µm. In the MER of nonliving animals, we obtained high-contrast embossed images of fine bones, gadolinium oxide particles in blood vessels, and iodine-based microspheres in coronary arteries of approximately 100 µm diameter.

  17. Magnification Embossed Radiography Utilizing Image-Shifting Subtraction Program

    NASA Astrophysics Data System (ADS)

    Akihiro Osawa,; Manabu Watanabe,; Eiichi Sato,; Hiroshi Matsukiyo,; Toshiyuki Enomoto,; Jiro Nagao,; Purkhet Abderyim,; Katsuo Aizawa,; Etsuro Tanaka,; Hidezo Mori,; Toshiaki Kawai,; Akira Ogawa,; Kiyomi Takahashi,; Shigehiro Sato,; Jun Onagawa,

    2010-03-01

    We developed an image-shifting subtraction program and carried out magnification embossed radiography (MER) utilizing single- and dual-energy subtractions. In particular, dual-energy subtraction was carried out to decrease the absorption contrast of unnecessary regions. The contrast resolution of the target region was increased by the use of subtraction software and a linear-contrast system in a flat-panel detector (FPD). The X-ray generator had a 100-μm-focus tube, and the subtractions were performed at tube voltages of 40 and 70 kV, a tube current of 0.50 mA, and an X-ray exposure time of 5.0 s. MER images with threefold magnification were obtained using the FPD with a pixel size of 48× 48 μm2, and the shifting dimensions of the imaged object in the horizontal and vertical directions ranged from 48 to 192 μm. At a shifting distance ranging from 48 to 144 μm, the spatial resolutions in the horizontal and vertical directions measured with a lead test chart were both 50 μm. In the MER of nonliving animals, we obtained high-contrast embossed images of fine bones, gadolinium oxide particles in blood vessels, and iodine-based microspheres in coronary arteries of approximately 100 μm diameter.

  18. Blind Source Separation Algorithms for PSF Subtraction from Direct Imaging

    NASA Astrophysics Data System (ADS)

    Shapiro, Jacob; Ranganathan, Nikhil; Savransky, Dmitry; Ruffio, Jean-Baptise; Macintosh, Bruce; GPIES Team

    2017-01-01

    The principal difficulty with detecting planets via direct imaging is that the target signal is similar in magnitude, or fainter, than the noise sources in the image. To compensate for this, several methods exist to subtract the PSF of the host star and other confounding noise sources. One of the most effective methods is Karhunen-Loève Image Processing (KLIP). The core algorithm within KLIP is Principal Component Analysis, which is a member of a class of algorithms called Blind Source Separation (BSS).We examine three other BSS algorithms that may potentially also be used for PSF subtraction: Independent Component Analysis, Stationary Subspace Analysis, and Common Spatial Pattern Filtering. The underlying principles of each of the algorithms is discussed, as well as the processing steps needed to achieve PSF subtraction. The algorithms are examined both as primary PSF subtraction techniques, as well as additional postprocessing steps used with KLIP.These algorithms have been used on data from the Gemini Planet Imager, analyzing images of β Pic b. To build a reference library, both Angular Differential Imaging and Spectral Differential Imaging were used. To compare to KLIP, three major metrics are examined: computation time, signal-to-noise ratio, and astrometric and photometric biases in different image regimes (e.g., speckle-dominated compared to Poisson-noise dominated). Preliminary results indicate that these BSS algorithms improve performance when used as an enhancement for KLIP, and that they can achieve similar SNR when used as the primary method of PSF subtraction.

  19. Digital Longitudinal Tomosynthesis

    NASA Astrophysics Data System (ADS)

    Rimkus, Daniel Steven

    1985-12-01

    The purpose of this dissertation was to investigate the clinical utility of digital longitudinal tomosynthesis in radiology. By acquiring a finite group of digital images during a longitudinal tomographic exposure, and processing these images, tomographic planes, other than the fulcrum plane, can be reconstructed. This process is now termed "tomosynthesis". A prototype system utilizing this technique was developed. Both phantom and patient studies were done with this system. The phantom studies were evaluated by subjective, visual criterion and by quantitative analysis of edge sharpness and noise in the reconstructions. Two groups of patients and one volunteer were studied. The first patient group consisted of 8 patients undergoing intravenous urography (IVU). These patients had digital tomography and film tomography of the abdomen. The second patient group consisted of 4 patients with lung cancer admitted to the hospital for laser resection of endobronchial tumor. These patients had mediastinal digital tomograms to evaluate the trachea and mainstem bronchi. The knee of one volunteer was imaged by film tomography and digital tomography. The results of the phantom studies showed that the digital reconstructions accurately produced images of the desired planes. The edge sharpness of the reconstructions approached that of the acquired images. Adequate reconstructions were achieved with as few as 5 images acquired during the exposure, with the quality of the reconstructions improving as the number of images acquired increased. The IVU patients' digital studies had less contrast and spatial resolution than the film tomograms. The single renal lesion visible on the film tomograms was also visible in the digital images. The digital mediastinal studies were felt by several radiologists to be superior to a standard chest xray in evaluating the airways. The digital images of the volunteer's knee showed many of the same anatomic features as the film tomogram, but the digital

  20. pyKLIP: PSF Subtraction for Exoplanets and Disks

    NASA Astrophysics Data System (ADS)

    Wang, Jason J.; Ruffio, Jean-Baptise; De Rosa, Robert J.; Aguilar, Jonathan; Wolff, Schuyler G.; Pueyo, Laurent

    2015-06-01

    pyKLIP subtracts out the stellar PSF to search for directly-imaged exoplanets and disks using a Python implementation of the Karhunen-Loève Image Projection (KLIP) algorithm. pyKLIP supports ADI, SDI, and ADI+SDI to model the stellar PSF and offers a large array of PSF subtraction parameters to optimize the reduction. pyKLIP relies on a minimal amount of dependencies (numpy, scipy, and astropy) and parallelizes the KLIP algorithm to speed up the reduction. pyKLIP supports GPI and P1640 data and can interface with other data sources with the addition of new modules. It also can inject simulated planets and disks as well as automatically search for point sources in PSF-subtracted data.

  1. Sky background subtraction with fiber-fed spectrographs

    NASA Astrophysics Data System (ADS)

    Puech, M.; Rodrigues, M.; Yang, Y.; Flores, H.; Royer, F.; Disseau, K.; Gonçalves, T.; Hammer, F.; Cirasuolo, M.; Evans, C. J.; Li Causi, G.; Maiolino, R.; Melo, C.

    2014-08-01

    Fiber-fed spectrographs can now have throughputs equivalent to slit spectrographs. However, the sky subtraction accuracy that can be reached on such instruments has often been pinpointed as one of their major issues, in relation to difficulties in scattered light and flat-field corrections or throughput losses associated with fibers. Using technical time observations with FLAMES-GIRAFFE, two observing techniques, namely dual staring and cross beam switching modes, were tested and the resulting sky subtraction accuracy reached in both cases was quantified. Results indicate that an accuracy of 0.6% on the sky subtraction can be reached, provided that the cross beam switching mode is used. This is very encouraging regarding the detection of very faint sources with future fiber-fed spectrographs such as VLT/MOONS or E-ELT/MOSAIC.

  2. Proposed smart integrated-optical preprocessor using holographic subtraction

    NASA Technical Reports Server (NTRS)

    Verber, C. M.; Vahey, D. W.

    1979-01-01

    The paper presents a proposed integrated-optical preprocessor with a holographic subtraction. It is based on an optical analog of a set of N analog voltages formed by passing an optical plane wave, confined in an electrooptic waveguide, under a set of N electrodes to which the voltages are applied; in the limit in which diffraction is ignored, the wavefront of the emerging guided wave will have superimposed upon it N discrete phase shifts. Processors which operate upon voltages encoded in this manner are being fabricated; they include a comparator in which incoming data are compared to a holographic record of the optical analog of a reference set, and a 'smart' system based upon holographic self-subtraction, in which the processor can independently adapt to changes in background information. The preprocessor operation is described in the screening, identification, and the self-subtraction modes, and implementation of devices in an integrated optical configuration is discussed.

  3. Subtraction Radiography for the Diagnosis of Bone Lesions in Dogs.

    DTIC Science & Technology

    1984-05-31

    AD-A142 726 SUBTRACTION RADIOGRAPHY FOR THE DIAGNOSIS OF BONE • LESIONS IN DOGS (U) ARMY INST OF DENTAL RESEARCH WASHINGTON DC M P RETHMRN ET AL. 31...11sk01 o -py- Rt one. Lesions in Dogs 11,4 -OG. 3(0?NUL AU THOR~q caraACT 0R GRANT NUMBER,&) * * __ M.P. Rethman, U.E. Ruttiman, R.B. O’Neal, R.I...research article titled "Subtraction Radiography for the Diagnosis of Bone Lesions in Dogs " solely to the Journal of Periodontology for review and

  4. Nonlinear Optical Image Subtraction For Potential Industrial Applications

    NASA Astrophysics Data System (ADS)

    Chiou, Arthur E.; Yeh, Pochi; Khoshnevisan, Monte

    1988-05-01

    Recent advances in optical phase conjugation and energy coupling at optical powers as low as a few milliwatts have added a new dimension to optical image processing. Conventional image processing techniques based on convolution/correlation, matched filtering, and holographic interferometry can now be achieved with much simpler components and usually at much higher efficiency by incorporating these new features. Some of the application concepts that had been impracticable can now be realized. The basic principle and potential industrial applications of real-time image subtraction using dynamic holograms are reviewed. Optical implementations and experimental results on image subtraction, novelty filtering, and defect detection are discussed.

  5. Sustained hypotension following intravenous metoclopramide.

    PubMed

    Nguyen, Tammy T; Petzel Gimbar, Renee M

    2013-11-01

    To report a case of sustained hypotension associated with the use of intravenous metoclopramide. A 50-year-old woman developed a hypotensive episode lasting approximately 90 minutes after the administration intravenous metoclopramide for the treatment of a migraine. The patient presented to the emergency department after she woke up with a severe headache that was much worse than her normal migraine headaches. Her past medical history included migraines, diabetes type 2, hypertension, and hyperlipidemia. Fifteen minutes after the administration of intravenous metoclopramide 10 mg, the patient's systolic blood pressure decreased from 138 to 84 mmHg (a mean arterial pressure decrease of 40.7 mmHg). The patient was given 1 L of intravenous NaCl 0.9% that had minimal effect on blood pressure. The patient did not reapproach her baseline systolic blood pressure until 90 minutes after the metoclopramide administration when it was measured at 138 mmHg. Subsequent contrast tomography of the head was negative and the patient's headache was successfully treated with butalbital/acetaminophen/caffeine. The patient was discharged home the same day. There are few published case reports of metoclopramide-induced hypotension in the current literature. Of those published, all showed transient hypotension with metoclopramide, lasting seconds to minutes. An objective causality assessment for drug-associated adverse drug reaction showed metoclopramide as a probable cause of the patient's hypotension (Naranjo score of 5). In this case, several indicators of metoclopramide induced hypotension were evident, including the timing of the hypotension after drug administration and the lack of any other possible causes of hypotension. This is the first published case report of sustained hypotension due to intravenous metoclopramide. Intravenous metoclopramide may cause sustained episodes of hypotension.

  6. Predictors of Morbidity and Cleavage Plane in Surgical Resection of Pure Convexity Meningiomas Using Cerebrospinal Fluid Sensitive Image Subtraction Magnetic Resonance Imaging

    PubMed Central

    THENIER-VILLA, José LUIS; CAMPOVERDE, Raúl ALEJANDRO GALÁRRAGA; DE LA LAMA ZARAGOZA, Adolfo RAMÓN; ALONSO, Cesáreo CONDE

    2017-01-01

    Meningiomas are the most common primary intracranial tumors. Since the adhesions in the plane of dissection are of interest in surgical planning, we suggest that digital image subtraction of FLAIR data from the T2 sequence of MRI may represent better the CSF spaces in the brain–tumor interface and may be a predictor of the intraoperative cleavage plane. From 2006 to 2016, 83 convexity meningiomas were resected in the Department of Neurosurgery of the University Hospital Complex of Vigo, an analysis of preoperative MRI was performed to assess peritumoral edema (PTE), tumor volume, among others; a digital subtraction of T2-FLAIR sequences was performed and analyzed in relationship to the cleavage plane described in the intraoperative report and postoperative neurological deficits. Simpson grade 1 resection was achieved in 85.54%, the overall 5-year PFS was 93.75%. Our rate of permanent new neurological deficit was 4.82% and the overall complication rate of 14.46%. The grade of PTE was proportional to tumor volume, 20 ± 2.8, 30 ± 5.3, and 34 ± 4.3 cm3 for grades 1, 2, and 3, respectively, positive cleft sign on image subtraction was predictive of good intraoperative cleavage plane and low grade cleavage plane (P = 0.04), and was a protective factor for postoperative neurological deficit (P = 0.02). Positive cleft sign in T2-FLAIR digital subtraction image is an independent predictor of good intraoperative cleavage plane, PTE is an independent predictor of the bad cleavage plane. Negative cleft sign in the image subtraction and a bad intraoperative cleavage plane are predictors of postoperative neurological deficit. PMID:27580930

  7. Aspiration Thrombectomy After Intravenous Alteplase Versus Intravenous Alteplase Alone.

    PubMed

    Mocco, J; Zaidat, Osama O; von Kummer, Rüdiger; Yoo, Albert J; Gupta, Rishi; Lopes, Demetrius; Frei, Don; Shownkeen, Harish; Budzik, Ron; Ajani, Zahra A; Grossman, Aaron; Altschul, Dorethea; McDougall, Cameron; Blake, Lindsey; Fitzsimmons, Brian-Fred; Yavagal, Dileep; Terry, John; Farkas, Jeffrey; Lee, Seon Kyu; Baxter, Blaise; Wiesmann, Martin; Knauth, Michael; Heck, Donald; Hussain, Syed; Chiu, David; Alexander, Michael J; Malisch, Timothy; Kirmani, Jawad; Miskolczi, Laszlo; Khatri, Pooja

    2016-09-01

    Thrombectomy, primarily with stent retrievers with or without adjunctive aspiration, provided clinical benefit across multiple prospective randomized trials. Whether this benefit is exclusive to stent retrievers is unclear. THERAPY (The Randomized, Concurrent Controlled Trial to Assess the Penumbra System's Safety and Effectiveness in the Treatment of Acute Stroke; NCT01429350) was an international, multicenter, prospective, randomized (1:1), open label, blinded end point evaluation, concurrent controlled clinical trial of aspiration thrombectomy after intravenous alteplase (IAT) administration compared with intravenous-alteplase alone in patients with large vessel ischemic stroke because of a thrombus length of ≥8 mm. The primary efficacy end point was the percent of patients achieving independence at 90 days (modified Rankin Scale score, 0-2; intention-to-treat analysis). The primary safety end point was the rate of severe adverse events (SAEs) by 90 days (as treated analysis). Patients were randomized 1:1 across 36 centers in 2 countries (United States and Germany). Enrollment was halted after 108 (55 IAT and 53 intravenous) patients (of 692 planned) because of external evidence of the added benefit of endovascular therapy to intravenous-alteplase alone. Functional independence was achieved in 38% IAT and 30% intravenous intention-to-treat groups (P=0.52). Intention-to-treat ordinal modified Rankin Scale odds ratio was 1.76 (95% confidence interval, 0.86-3.59; P=0.12) in favor of IAT. Secondary efficacy analyses all demonstrated a consistent direction of effect toward benefit of IAT. No differences in symptomatic intracranial hemorrhage rates (9.3% IAT versus 9.7% intravenous, P=1.0) or 90-day mortality (IAT: 12% versus intravenous: 23.9%, P=0.18) were observed. THERAPY did not achieve its primary end point in this underpowered sample. Directions of effect for all prespecified outcomes were both internally and externally consistent toward benefit. It is

  8. Detectors for digital mammography.

    PubMed

    Yaffe, Martin J; Mainprize, James G

    2004-08-01

    Interest in digital radiography was stimulated by the enthusiastic acceptance of computed tomography in the early 1970s. It quickly became apparent to the medical community that images with improved information content, whose display characteristics could be manipulated by the viewer, provided many advantages. Subsequently, digital systems for subtraction angiography and later for conventional projection radiography and fluoroscopy were developed. The timing of the introduction of these systems was highly dependent on the readiness of certain key component technologies to meet the requirements of each of these applications. These components are the x-ray detectors, analog to digital converters, computers, data storage systems and high-resolution electronic displays and printers used in image acquisition, storage and display. Mammography represents one of the most demanding radiographic applications, simultaneously requiring excellent contrast sensitivity, high spatial resolution, and wide dynamic range at as low as radiation dose to the breast as is reasonably achievable while meeting the other requirements. For this reason, it is one of the last radiographic procedures to "go digital". Here, some of the considerations related to the detector technology for digital mammography will be discussed and systems currently available will be described.

  9. [Complications caused by intravenous therapy].

    PubMed

    Quirós Luque, José María; Gago Fornells, Manuel

    2005-11-01

    Nursing professionals must know everything related to complications caused by intravenous therapy including the ways to prevent and solve these complications. We need not forget that nurses are the ones mainly responsible for the insertion, manipulation, removal and care of catheters.

  10. [Lethal intravenous injection of benzine].

    PubMed

    Zirwes, Christian; Ritz-Timme, Stefanie; Hinsch, Nora; Kardel, Bernd; Hartung, Benno

    2015-01-01

    A man who suffered from chronic pain syndrome died two days after intravenous injection of 2 ml benzine. Previous suicide attempts by drug intoxication and strangulation had failed. Death occurred due to multi-organ failure. We present the results of the clinical, morphological and toxicological examinations performed.

  11. Symmetric point quartic gluon vertex and momentum subtraction

    NASA Astrophysics Data System (ADS)

    Gracey, J. A.

    2014-07-01

    We compute the full one loop correction to the quartic vertex of QCD at the fully symmetric point. This allows us to define a new momentum subtraction (MOM) scheme in the class of schemes introduced by Celmaster and Gonsalves. Hence using properties of the renormalization group equation, the two loop renormalization group functions for this scheme are given.

  12. "Abuelita" Epistemologies: Counteracting Subtractive Schools in American Education

    ERIC Educational Resources Information Center

    Gonzales, Sandra M.

    2015-01-01

    This autoethnographic inquiry examines the intersection of elder epistemology and subtractive education, exploring how one "abuelita" countered her granddaughter's divestment of Mexican-ness. I demonstrate how the grandmother used "abuelita" epistemologies to navigate this tension and resist the assimilative pressures felt…

  13. Cutaneous Force Feedback as a Sensory Subtraction Technique in Haptics.

    PubMed

    Prattichizzo, D; Pacchierotti, C; Rosati, G

    2012-01-01

    A novel sensory substitution technique is presented. Kinesthetic and cutaneous force feedback are substituted by cutaneous feedback (CF) only, provided by two wearable devices able to apply forces to the index finger and the thumb, while holding a handle during a teleoperation task. The force pattern, fed back to the user while using the cutaneous devices, is similar, in terms of intensity and area of application, to the cutaneous force pattern applied to the finger pad while interacting with a haptic device providing both cutaneous and kinesthetic force feedback. The pattern generated using the cutaneous devices can be thought as a subtraction between the complete haptic feedback (HF) and the kinesthetic part of it. For this reason, we refer to this approach as sensory subtraction instead of sensory substitution. A needle insertion scenario is considered to validate the approach. The haptic device is connected to a virtual environment simulating a needle insertion task. Experiments show that the perception of inserting a needle using the cutaneous-only force feedback is nearly indistinguishable from the one felt by the user while using both cutaneous and kinesthetic feedback. As most of the sensory substitution approaches, the proposed sensory subtraction technique also has the advantage of not suffering from stability issues of teleoperation systems due, for instance, to communication delays. Moreover, experiments show that the sensory subtraction technique outperforms sensory substitution with more conventional visual feedback (VF).

  14. Children's Understanding of the Relationship between Addition and Subtraction

    ERIC Educational Resources Information Center

    Gilmore, Camilla K.; Spelke, Elizabeth S.

    2008-01-01

    In learning mathematics, children must master fundamental logical relationships, including the inverse relationship between addition and subtraction. At the start of elementary school, children lack generalized understanding of this relationship in the context of exact arithmetic problems: they fail to judge, for example, that 12 + 9 - 9 yields…

  15. "Abuelita" Epistemologies: Counteracting Subtractive Schools in American Education

    ERIC Educational Resources Information Center

    Gonzales, Sandra M.

    2015-01-01

    This autoethnographic inquiry examines the intersection of elder epistemology and subtractive education, exploring how one "abuelita" countered her granddaughter's divestment of Mexican-ness. I demonstrate how the grandmother used "abuelita" epistemologies to navigate this tension and resist the assimilative pressures felt…

  16. Insight into Subtraction from Large-Scale Assessment Data

    ERIC Educational Resources Information Center

    Morley, Patricia

    2013-01-01

    The data from the national tests such as the National Assessment Program Literacy and Numeracy (NAPLAN) and its precursor Victorian Achievement Improvement Monitor (AIM) are an important resource. The 2006 Year 3 AIM assessment included two subtraction items that are similar in content, and which are presented without text or images. The detailed,…

  17. Adding and Subtracting Vectors: The Problem with the Arrow Representation

    ERIC Educational Resources Information Center

    Heckler, Andrew F.; Scaife, Thomas M.

    2015-01-01

    A small number of studies have investigated student understanding of vector addition and subtraction in generic or introductory physics contexts, but in almost all cases the questions posed were in the vector arrow representation. In a series of experiments involving over 1000 students and several semesters, we investigated student understanding…

  18. Addition and Subtraction by Students with Down Syndrome

    ERIC Educational Resources Information Center

    Herrera, Aurelia Noda; Bruno, Alicia; Gonzalez, Carina; Moreno, Lorenzo; Sanabria, Hilda

    2011-01-01

    We present a research report on addition and subtraction conducted with Down syndrome students between the ages of 12 and 31. We interviewed a group of students with Down syndrome who executed algorithms and solved problems using specific materials and paper and pencil. The results show that students with Down syndrome progress through the same…

  19. A New Sky Subtraction Technique for Low Surface Brightness Data

    NASA Astrophysics Data System (ADS)

    Katkov, I. Y.; Chilingarian, I. V.

    2011-07-01

    We present a new approach to the sky subtraction for long-slit spectra that is suitable for low-surface brightness objects based on the controlled reconstruction of the night sky spectrum in the Fourier space using twilight or arc-line frames as references. It can be easily adopted for FLAMINGOS-type multi-slit data. Compared to existing sky subtraction algorithms, our technique is taking into account variations of the spectral line spread along the slit thus qualitatively improving the sky subtraction quality for extended targets. As an example, we show how the stellar metallicity and stellar velocity dispersion profiles in the outer disc of the spiral galaxy NGC5440 are affected by the sky subtraction quality. Our technique is used in the survey of early-type galaxies carried out at the Russian 6-m telescope, and it strongly increases the scientific potential of large amounts of long-slit data for nearby galaxies available in major data archives.

  20. Teaching Children about the Inverse Relation between Addition and Subtraction

    ERIC Educational Resources Information Center

    Nunes, Terezinha; Bryant, Peter; Hallett, Darcy; Bell, Daniel; Evans, Deborah

    2009-01-01

    Two intervention studies are described. Both were designed to study the effects of teaching children about the inverse relation between addition and subtraction. The interventions were successful with 8-year-old children in Study 1 and to a limited extent with 5-year-old children in Study 2. In Study 1 teaching children about inversion increased…

  1. Teaching Children about the Inverse Relation between Addition and Subtraction

    ERIC Educational Resources Information Center

    Nunes, Terezinha; Bryant, Peter; Hallett, Darcy; Bell, Daniel; Evans, Deborah

    2009-01-01

    Two intervention studies are described. Both were designed to study the effects of teaching children about the inverse relation between addition and subtraction. The interventions were successful with 8-year-old children in Study 1 and to a limited extent with 5-year-old children in Study 2. In Study 1 teaching children about inversion increased…

  2. Children's Understanding of the Addition/Subtraction Complement Principle

    ERIC Educational Resources Information Center

    Torbeyns, Joke; Peters, Greet; De Smedt, Bert; Ghesquière, Pol; Verschaffel, Lieven

    2016-01-01

    Background: In the last decades, children's understanding of mathematical principles has become an important research topic. Different from the commutativity and inversion principles, only few studies have focused on children's understanding of the addition/subtraction complement principle (if a - b = c, then c + b = a), mainly relying on verbal…

  3. Teaching Addition and Subtraction Facts: A Chinese Perspective.

    ERIC Educational Resources Information Center

    Sun, Wei; Zhang, Joanne Y.

    2001-01-01

    Presents an issue that arises in every country: How can teachers best help children master basic addition and subtraction facts? Discusses how this is handled in China and highlights the impact that language has on how children think about numbers. (KHR)

  4. Addition and Subtraction by Students with Down Syndrome

    ERIC Educational Resources Information Center

    Herrera, Aurelia Noda; Bruno, Alicia; Gonzalez, Carina; Moreno, Lorenzo; Sanabria, Hilda

    2011-01-01

    We present a research report on addition and subtraction conducted with Down syndrome students between the ages of 12 and 31. We interviewed a group of students with Down syndrome who executed algorithms and solved problems using specific materials and paper and pencil. The results show that students with Down syndrome progress through the same…

  5. Cognitive Functioning and Performance on Addition and Subtraction Algorithms.

    ERIC Educational Resources Information Center

    Romberg, Thomas A.; Collis, Kevin F.

    The purpose of this study was to ascertain whether children in grade 3 who differ in cognitive processing capacity add and subtract differently. The researchers drew upon information from three sources: individual results from a battery of 14 tests, an objective-referenced achievement test measuring a variety of arithmetic skills related to…

  6. Children's Understanding of the Addition/Subtraction Complement Principle

    ERIC Educational Resources Information Center

    Torbeyns, Joke; Peters, Greet; De Smedt, Bert; Ghesquière, Pol; Verschaffel, Lieven

    2016-01-01

    Background: In the last decades, children's understanding of mathematical principles has become an important research topic. Different from the commutativity and inversion principles, only few studies have focused on children's understanding of the addition/subtraction complement principle (if a - b = c, then c + b = a), mainly relying on verbal…

  7. Isolation of ultrasonic scattering by wavefield baseline subtraction

    NASA Astrophysics Data System (ADS)

    Dawson, Alexander J.; Michaels, Jennifer E.; Michaels, Thomas E.

    2016-03-01

    Wavefield imaging generally refers to the measurement of signals over a two-dimensional rectilinear grid that originate from a spatially fixed source. Subtraction of such wavefields is investigated as a means of separating scattered signals from the total wavefield; that is, baseline wavefield data acquired from a defect-free specimen are subtracted from analogous data acquired after introduction of a defect. The wavefields considered here are generated by a 5 MHz angle-beam probe and measured over an area of the accessible specimen surface using a laser vibrometer. The primary challenge in isolating the scattered waves is imperfect temporal and spatial alignment of the two wavefields. Two methods for aligning the wavefields in space and time prior to performing baseline subtraction are presented and their efficacy is evaluated using data acquired before and after introducing notches that originate from a through-hole. Although perfect baseline subtraction is not achieved, the improvement in performance after alignment using either method allows for scattered waves from small defects to be separated and visualized, even when their amplitudes are much smaller than those of the incident waves.

  8. The Use of Taught and Invented Methods of Subtraction.

    ERIC Educational Resources Information Center

    Perry, A. D.; Stacey, Kaye

    1994-01-01

    Attempted to establish the incidence of using taught algorithms versus invented methods of subtraction in (n=1,370) male secondary school students and to relate the use of invented methods to age, mathematical achievement, and lateral thinking ability. Use of invented algorithms increased with age. (23 references) (MKR)

  9. Adding and Subtracting Vectors: The Problem with the Arrow Representation

    ERIC Educational Resources Information Center

    Heckler, Andrew F.; Scaife, Thomas M.

    2015-01-01

    A small number of studies have investigated student understanding of vector addition and subtraction in generic or introductory physics contexts, but in almost all cases the questions posed were in the vector arrow representation. In a series of experiments involving over 1000 students and several semesters, we investigated student understanding…

  10. Efficacy of sealing proximal early active lesions: an 18-month clinical study evaluated by conventional and subtraction radiography.

    PubMed

    Martignon, S; Ekstrand, K R; Ellwood, R

    2006-01-01

    This study assessed the efficacy of sealing proximal lesions on adult patients using a split-mouth design. Eighty-two 15- to 39-year-olds from the Dental Faculties in Copenhagen and Bogotá participated, each having 2 or more proximal lesions in the following radiographic stages: (1) lesion restricted to the outer half of enamel; (2) lesion from the inner half of enamel including the enamel dentine junction, and (3) lesion restricted to the outer third of dentine. Standardized geometrically aligned baseline and follow-up radiographs were obtained. One randomly selected lesion (test) in each patient was sealed with 1 of 2 resins. The patients were instructed to floss all the proximal lesions 3 times per week. The baseline to 18 months difference in caries lesion progression status was assessed using 3 methods: (1) radiographs were independently assessed visually; (2) radiographs were read in pairs, and (3) using subtraction radiography of digitized images. A total of 72 subjects finished the study (12.2% dropout). The compliance concerning flossing was poor (15%). For the repeated examinations kappa was 0.84 for the visual examination, 0.44 for the paired readings and 0.84 for the subtraction examination. Two test lesions and 1 control lesion were restored. For the independent radiograph assessment method 10 and 26% progressed in the test and control group, respectively (p > 0.05); with the paired radiograph method the corresponding data were 22% in the test and 47% in the control groups (p < 0.01). By subtraction radiography 44% of the test group and 84% of the control were judged to have progressed (p < 0.001). The sealing technique was superior to instructing patients to floss, and subtraction radiography appeared to be the most sensitive method for assessing lesion progression. Copyright 2006 S. Karger AG, Basel.

  11. Parathyroid cyst with adenoma on thallium-201/technetium-99m subtraction imaging

    SciTech Connect

    Joo, K.G.; Baeumler, G.R.

    1987-04-01

    A case of a parathyroid cyst with adenoma was seen on Tl-201/Tc-99m subtraction imaging. The literature regarding parathyroid cysts and the subtraction technique for parathyroid adenoma imaging was reviewed.

  12. [Intravenous remifentanyl for labor analgesia].

    PubMed

    Arnal, D; Serrano, M L; Corral, E M; García del Valle, S

    2009-04-01

    Intravenous remifentanil may be the preferred analgesic when regional techniques are contraindicated. To perform a systematic review on the use of remifentanil for analgesia in labor. We searched MEDLINE (January 1995-August 2007) for studies on obstetric analgesia with remifentanil. We found 32 references representing the use of remifentanil in 257 women in labor. In most cases, patients reported relief of pain and a high level of satisfaction, with no severe side effects in mothers or neonates. When compared with meperidine and nitrous oxide in clinical trials, remifentanil provided better analgesia with fewer adverse effects. Analgesia with intravenous remifentanil is more effective and safer than other alternatives to regional analgesic techniques in obstetrics. Nevertheless, the optimum system for infusing the drug must b e established and further studies of maternal and fetal safety should be carried out.

  13. Intravenous bisphosphonates for postmenopausal osteoporosis

    PubMed Central

    Mottaghi, Peyman

    2010-01-01

    Numerous clinical studies have shown bisphoshonates (BPs) to be useful and cost-effective options for the fractures prevention and postmenopausal bone loss. The use of oral bisphoshonates is an established option for managment of osteoporosis in postmenopausal women, but many of them complaint from gastrointestinal side effect or frequently dosed oral regimens. To improve upon the suboptimal therapeutic compliance in postmenopausal women, newer, longer-acting intravenous formulations of BPs has been approved for intermittent administration in postmenopausal women. These preparations would become an option for patients who can not tolerate oral BPs or it was ineffective in increasing their bone density. This article proposed to review effectiveness and tolerability of intravenous BPs in postmenopausal women with osteoporosis. PMID:21526078

  14. Intravenous Solutions for Exploration Missions

    NASA Technical Reports Server (NTRS)

    Miller, Fletcher J.; Niederhaus, Charles; Barlow, Karen; Griffin, DeVon

    2007-01-01

    This paper describes the intravenous (IV) fluids requirements being developed for medical care during NASA s future exploration class missions. Previous research on IV solution generation and mixing in space is summarized. The current exploration baseline mission profiles are introduced, potential medical conditions described and evaluated for fluidic needs, and operational issues assessed. We briefly introduce potential methods for generating IV fluids in microgravity. Conclusions on the recommended fluid volume requirements are presented.

  15. Subtraction of Positive and Negative Numbers: The Difference and Completion Approaches with Chips

    ERIC Educational Resources Information Center

    Flores, Alfinio

    2008-01-01

    Diverse contexts such as "take away," comparison," and "completion" give rise to subtraction problems. The take-away interpretation of subtraction has been explored using two-colored chips to help students understand addition and subtraction of integers. This article illustrates how the difference and completion (or missing addend) interpretations…

  16. Number Words in Young Children's Conceptual and Procedural Knowledge of Addition, Subtraction and Inversion

    ERIC Educational Resources Information Center

    Canobi, Katherine H.; Bethune, Narelle E.

    2008-01-01

    Three studies addressed children's arithmetic. First, 50 3- to 5-year-olds judged physical demonstrations of addition, subtraction and inversion, with and without number words. Second, 20 3- to 4-year-olds made equivalence judgments of additions and subtractions. Third, 60 4- to 6-year-olds solved addition, subtraction and inversion problems that…

  17. Number Words in Young Children's Conceptual and Procedural Knowledge of Addition, Subtraction and Inversion

    ERIC Educational Resources Information Center

    Canobi, Katherine H.; Bethune, Narelle E.

    2008-01-01

    Three studies addressed children's arithmetic. First, 50 3- to 5-year-olds judged physical demonstrations of addition, subtraction and inversion, with and without number words. Second, 20 3- to 4-year-olds made equivalence judgments of additions and subtractions. Third, 60 4- to 6-year-olds solved addition, subtraction and inversion problems that…

  18. Subtraction of Positive and Negative Numbers: The Difference and Completion Approaches with Chips

    ERIC Educational Resources Information Center

    Flores, Alfinio

    2008-01-01

    Diverse contexts such as "take away," comparison," and "completion" give rise to subtraction problems. The take-away interpretation of subtraction has been explored using two-colored chips to help students understand addition and subtraction of integers. This article illustrates how the difference and completion (or missing addend) interpretations…

  19. Intensive intravenous regime for acute severe colitis.

    PubMed

    Banerjee, Rupa; Philip, Matthew; Bhatia, Shobna

    2014-08-01

    Acute severe exacerbation of ulcerative colitis is a potentially life threatening medical emergency. The management of acute severe ulcerative colitis depends on early recognition and prompt initiation of intensive intravenous treatment along with continuous objective monitoring for possible medical failure. The intensive regime is the accepted standard of care. This includes primarily a) intravenous corticosteroids, b) intravenous supportive management, and d) intravenous antibiotics in instances. This review discusses the timing, duration and dosage of the intensive intravenous treatment including the evidence based protocol for effective monitoring to enable timely escalation to second line therapy & colectomy.

  20. Power corrections in the N -jettiness subtraction scheme

    DOE PAGES

    Boughezal, Radja; Liu, Xiaohui; Petriello, Frank

    2017-03-30

    We discuss the leading-logarithmic power corrections in the N-jettiness subtraction scheme for higher-order perturbative QCD calculations. We compute the next-to-leading order power corrections for an arbitrary N-jet process, and we explicitly calculate the power correction through next-to-next-to-leading order for color-singlet production for bothmore » $$q\\bar{q}$$ and gg initiated processes. Our results are compact and simple to implement numerically. Including the leading power correction in the N-jettiness subtraction scheme substantially improves its numerical efficiency. Finally, we discuss what features of our techniques extend to processes containing final-state jets.« less

  1. Robust Background Subtraction with Foreground Validation for Urban Traffic Video

    SciTech Connect

    Cheung, S S; Kamath, C

    2004-01-15

    Identifying moving objects in a video sequence is a fundamental and critical task in many computer-vision applications. Background subtraction techniques are commonly used to separate foreground moving objects from the background. Most background subtraction techniques assume a single rate of adaptation, which is inadequate for complex scenes such as a traffic intersection where objects are moving at different and varying speeds. In this paper, we propose a foreground validation algorithm that first builds a foreground mask using a slow-adapting Kalman filter, and then validates individual foreground pixels by a simple moving object model, built using both the foreground and background statistics as well as the frame difference. Ground-truth experiments with urban traffic sequences show that our proposed algorithm significantly improves upon results using only Kalman filter or frame-differencing, and outperforms other techniques based on mixture of Gaussians, median filter, and approximated media filter.

  2. ZAP - enhanced PCA sky subtraction for integral field spectroscopy

    NASA Astrophysics Data System (ADS)

    Soto, Kurt T.; Lilly, Simon J.; Bacon, Roland; Richard, Johan; Conseil, Simon

    2016-05-01

    We introduce Zurich Atmosphere Purge (ZAP), an approach to sky subtraction based on principal component analysis (PCA) that we have developed for the Multi Unit Spectrographic Explorer (MUSE) integral field spectrograph. ZAP employs filtering and data segmentation to enhance the inherent capabilities of PCA for sky subtraction. Extensive testing shows that ZAP reduces sky emission residuals while robustly preserving the flux and line shapes of astronomical sources. The method works in a variety of observational situations from sparse fields with a low density of sources to filled fields in which the target source fills the field of view. With the inclusion of both of these situations, the method is generally applicable to many different science cases and should also be useful for other instrumentation. ZAP is available for download at http://muse-vlt.eu/science/tools.

  3. Spinal pedicle subtraction osteotomy for fixed sagittal imbalance patients

    PubMed Central

    Hyun, Seung-Jae; Kim, Yongjung J; Rhim, Seung-Chul

    2013-01-01

    In addressing spinal sagittal imbalance through a posterior approach, the surgeon now may choose from among a variety of osteotomy techniques. Posterior column osteotomies such as the facetectomy or Ponte or Smith-Petersen osteotomy provide the least correction, but can be used at multiple levels with minimal blood loss and a lower operative risk. Pedicle subtraction osteotomies provide nearly 3 times the per-level correction of Ponte/Smith-Petersen osteotomies; however, they carry increased technical demands, longer operative time, and greater blood loss and associated significant morbidity, including neurological injury. The literature focusing on pedicle subtraction osteotomy for fixed sagittal imbalance patients is reviewed. The long-term overall outcomes, surgical tips to reduce the complications and suggestions for their proper application are also provided. PMID:24340276

  4. Noise Reduction using Frequency Sub-Band Adaptive Spectral Subtraction

    NASA Technical Reports Server (NTRS)

    Kozel, David

    2000-01-01

    A frequency sub-band based adaptive spectral subtraction algorithm is developed to remove noise from noise-corrupted speech signals. A single microphone is used to obtain both the noise-corrupted speech and the estimate of the statistics of the noise. The statistics of the noise are estimated during time frames that do not contain speech. These statistics are used to determine if future time frames contain speech. During speech time frames, the algorithm determines which frequency sub-bands contain useful speech information and which frequency sub-bands contain only noise. The frequency sub-bands, which contain only noise, are subtracted off at a larger proportion so the noise does not compete with the speech information. Simulation results are presented.

  5. Removing Cardiac Artefacts in Magnetoencephalography with Resampled Moving Average Subtraction

    PubMed Central

    Ahlfors, Seppo P.; Hinrichs, Hermann

    2016-01-01

    Magnetoencephalography (MEG) signals are commonly contaminated by cardiac artefacts (CAs). Principle component analysis and independent component analysis have been widely used for removing CAs, but they typically require a complex procedure for the identification of CA-related components. We propose a simple and efficient method, resampled moving average subtraction (RMAS), to remove CAs from MEG data. Based on an electrocardiogram (ECG) channel, a template for each cardiac cycle was estimated by a weighted average of epochs of MEG data over consecutive cardiac cycles, combined with a resampling technique for accurate alignment of the time waveforms. The template was subtracted from the corresponding epoch of the MEG data. The resampling reduced distortions due to asynchrony between the cardiac cycle and the MEG sampling times. The RMAS method successfully suppressed CAs while preserving both event-related responses and high-frequency (>45 Hz) components in the MEG data. PMID:27503196

  6. Self-mixing differential vibrometer based on electronic channel subtraction.

    PubMed

    Donati, Silvano; Norgia, Michele; Giuliani, Guido

    2006-10-01

    An instrument for noncontact measurement of differential vibrations is developed, based on the self-mixing interferometer. As no reference arm is available in the self-mixing configuration, the differential mode is obtained by electronic subtraction of signals from two (nominally equal) vibrometer channels, taking advantage that channels are servo stabilized and thus insensitive to speckle and other sources of amplitude fluctuation. We show that electronic subtraction is nearly as effective as field superposition. Common-mode suppression is 25-30 dB, the dynamic range (amplitude) is in excess of 100 microm, and the minimum measurable (differential) amplitude is 20 nm on a B = 10 kHz bandwidth. The instrument has been used to measure vibrations of two metal samples kept in contact, revealing the hysteresis cycle in the microslip and gross-slip regimes, which are of interest in the study of friction induced vibration damping of gas turbine blades for aircraft applications.

  7. Background subtraction and transient timing with Bayesian Blocks

    NASA Astrophysics Data System (ADS)

    Worpel, H.; Schwope, A. D.

    2015-06-01

    Aims: We aim to incorporate background subtraction into the Bayesian Blocks algorithm so that transient events can be timed accurately and precisely even in the presence of a substantial, rapidly variable background. Methods: We developed several modifications to the algorithm and tested them on a simulated XMM-Newton observation of a bursting and eclipsing object. Results: We found that bursts can be found to good precision for almost all background-subtraction methods, but eclipse ingresses and egresses present problems for most methods. We found one method that recovered these events with precision comparable to the interval between individual photons, in which both source- and background-region photons are combined into a single list and weighted according to the exposure area. We also found that adjusting the Bayesian Blocks change points nearer to blocks with higher count rate removes a systematic bias towards blocks of low count rate.

  8. Realization of arithmetic addition and subtraction in a quantum system

    NASA Astrophysics Data System (ADS)

    Um, Mark; Zhang, Junhua; Lv, Dingshun; Lu, Yao; An, Shuoming; Zhang, Jing-Ning; Kim, Kihwan; Kim, M. S.; Nha, Hyunchul

    2015-05-01

    We report an experimental realization of the conventional arithmetic on a bosonic system, in particular, phonons of a 171Yb+ ion trapped in a harmonic potential. The conventional addition and subtraction are totally different from the quantum operations of creation ↠and annihilation â that have the modification of √{ n } factor due to the symmetric nature of bosons. In our realization, the addition and subtraction do not depend on the number of particles originally in the system and nearly deterministically bring a classical state into a non-classical state. We implement such operations by applying the scheme of transitionless shortcuts to adiabaticity on anti-Jaynes-Cummings transition. This technology enables quantum state engineering and can be applied to many other experimental platforms. This work was supported by the National Basic Research Program of China under Grants No. 2011CBA00300 (No. 2011CBA00301), the National Natural Science Foundation of China 11374178.

  9. Increasing entanglement between Gaussian states by coherent photon subtraction.

    PubMed

    Ourjoumtsev, Alexei; Dantan, Aurélien; Tualle-Brouri, Rosa; Grangier, Philippe

    2007-01-19

    We experimentally demonstrate that the entanglement between Gaussian entangled states can be increased by non-Gaussian operations. Coherent subtraction of single photons from Gaussian quadrature-entangled light pulses, created by a nondegenerate parametric amplifier, produces delocalized states with negative Wigner functions and complex structures more entangled than the initial states in terms of negativity. The experimental results are in very good agreement with the theoretical predictions.

  10. Subtractive Renormalization Group Invariance: Pionless EFT at NLO

    SciTech Connect

    Timoteo, Varese S.; Szpigel, Sergio; Duraes, Francisco O.

    2010-11-12

    We show some results concerning the renormalization group (RG) invariance of the nucleon-nucleon (NN) interaction in pionless effective field theory at next-to-leading order (NLO), using a non-relativistic Callan-Symanzik equation (NRCS) for the driving term of the Lippmann-Schwinger (LS) equation with three recursive subtractions. The phase-shifts obtained for the RG evolved potential are same as those for the original potential, apart from relative differences of order 10{sup -15}.

  11. Energy subtraction computed tomography measured by current-mode detector

    NASA Astrophysics Data System (ADS)

    Kanno, I.; Imamura, R.; Mikami, K.; Hashimoto, M.; Ohtaka, M.; Ara, K.; Nomiya, S.; Onabe, H.

    2009-10-01

    For the reduction of exposure dose in contrast media detection with X-ray transmission measurements, the energy measurement of X-rays and the energy subtraction (ES) method have been shown to be effective. To make the ES method applicable, a novel detector for unfolding the X-ray energy distribution was proposed by the authors. As an application of this novel detector, a CT image was reconstructed with ES data and compared with the image reconstructed using electric current data.

  12. Subtractive Renormalization Group Invariance: Pionless EFT at NLO

    NASA Astrophysics Data System (ADS)

    Timóteo, Varese S.; Szpigel, Sérgio; Durães, Francisco O.

    2010-11-01

    We show some results concerning the renormalization group (RG) invariance of the nucleon-nucleon (NN) interaction in pionless effective field theory at next-to-leading order (NLO), using a non-relativistic Callan-Symanzik equation (NRCS) for the driving term of the Lippmann-Schwinger (LS) equation with three recursive subtractions. The phase-shifts obtained for the RG evolved potential are same as those for the original potential, apart from relative differences of order 10-15.

  13. Genome subtraction for novel target definition in Salmonella typhi.

    PubMed

    Rathi, Bhawna; Sarangi, Aditya N; Trivedi, Nidhi

    2009-10-11

    Large genomic sequencing projects of pathogens as well as human genome leads to immense genomic and proteomic data which would be very beneficial for the novel target identification in pathogens. Subtractive genomic approach is one of the most useful strategies helpful in identification of potential targets. The approach works by subtracting the genes or proteins homologous to both host and the pathogen and identify those set of gene or proteins which are essential for the pathogen and are exclusively present in the pathogen. Subtractive genomic approach is employed to identify novel target in salmonella typhi. The pathogen has 4718 proteins out of which 300 are found to be essential (" indispensable to support cellular life") in the pathogen with no human homolog. Metabolic pathway analyses of these 300 essential proteins revealed that 149 proteins are exclusively involved in several metabolic pathway of S. typhi. 8 metabolic pathways are found to be present exclusively in the pathogen comprising of 27 enzymes unique to the pathogen. Thus, these 27 proteins may serve as prospective drug targets. Sub-cellular localization prediction of the 300 essential proteins was done which reveals that 11 proteins lie on the outer membrane of the pathogen which could be probable vaccine candidates.

  14. Addition and subtraction in wild New Zealand robins.

    PubMed

    Garland, Alexis; Low, Jason

    2014-11-01

    This experiment aimed to investigate proto-arithmetic ability in a wild population of New Zealand robins. We investigated numerical competence from the context of computation: behavioural responses to arithmetic operations over small numbers of prey objects (mealworms). Robins' behavioural responses (such as search time) to the simple addition and subtraction problems presented in a Violation of Expectancy (VoE) paradigm were measured. Either a congruent (expected) or incongruent (unexpected) quantity of food items were hidden in a trap door out of view of the subject. Within view of the subject, a quantity of items were added into (and in some cases subtracted from) the apparatus which was either the same as that hidden, or different. Robins were then allowed them to find a quantity that either preserved or violated addition and subtraction outcomes. Robins searched around the apparatus longer when presented with an incongruent scenario violating arithmetic rules, demonstrating potential proto-arithmetic awareness of changes in prey quantity. This article is part of a Special Issue entitled: Cognition in the wild.

  15. ROBUST TECHNIQUES FOR BACKGROUND SUBTRACTION IN URBAN TRAFFIC VIDEO

    SciTech Connect

    Kamath, C; Cheung, S S

    2003-10-28

    Identifying moving objects from a video sequence is a fundamental and critical task in many computer-vision applications. A common approach is to perform background subtraction, which identifies moving objects from the portion of a video frame that differs significantly from a background model. There are many challenges in developing a good background subtraction algorithm. First, it must be robust against changes in illumination. Second, it should avoid detecting non-stationary background objects such as swinging leaves, rain, snow, and shadow cast by moving objects. Finally, its internal background model should react quickly to changes in background such as starting and stopping of vehicles. In this paper, we compare various background subtraction algorithms for detecting moving vehicles and pedestrians in urban traffic video sequences. We consider approaches varying from simple techniques such as frame differencing and adaptive median filtering, to more sophisticated probabilistic modeling techniques. While complicated techniques often produce superior performance, our experiments show that simple techniques such as adaptive median filtering can produce good results with much lower computational complexity.

  16. Artifacts in digital coincidence timing

    SciTech Connect

    Moses, W. W.; Peng, Q.

    2014-10-16

    Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into a time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator.All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e. the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the 'optimal' method. In conclusion, the purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization.

  17. Artifacts in Digital Coincidence Timing

    PubMed Central

    Moses, W. W.; Peng, Q.

    2014-01-01

    Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into a time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator. All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e., the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the “optimal” method. The purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization. PMID:25321885

  18. Anatomical noise in contrast-enhanced digital mammography. Part I. Single-energy imaging

    SciTech Connect

    Hill, Melissa L.; Yaffe, Martin J.; Mainprize, James G.; Carton, Ann-Katherine; Muller, Serge; Ebrahimi, Mehran; Jong, Roberta A.; Dromain, Clarisse

    2013-05-15

    Purpose: The use of an intravenously injected iodinated contrast agent could help increase the sensitivity of digital mammography by adding information on tumor angiogenesis. Two approaches have been made for clinical implementation of contrast-enhanced digital mammography (CEDM), namely, single-energy (SE) and dual-energy (DE) imaging. In each technique, pairs of mammograms are acquired, which are then subtracted with the intent to cancel the appearance of healthy breast tissue to permit sensitive detection and specific characterization of lesions. Patterns of contrast agent uptake in the healthy parenchyma, and uncanceled signal from background tissue create a 'clutter' that can mask or mimic an enhancing lesion. This type of 'anatomical noise' is often the limiting factor in lesion detection tasks, and thus, noise quantification may be useful for cascaded systems analysis of CEDM and for phantom development. In this work, the authors characterize the anatomical noise in CEDM clinical images and the authors evaluate the influence of the x-ray energy used for acquisition, the presence of iodine in the breast, and the timing of imaging postcontrast administration on anatomical noise. The results are presented in a two-part report, with SE CEDM described here, and DE CEDM in Part II. Methods: A power law is used to model anatomical noise in CEDM images. The exponent, {beta}, which describes the anatomical structure, and the constant {alpha}, which represents the magnitude of the noise, are determined from Wiener spectra (WS) measurements on images. A total of 42 SE CEDM cases from two previous clinical pilot studies are assessed. The parameters {alpha} and {beta} are measured both from unprocessed images and from subtracted images. Results: Consistent results were found between the two SE CEDM pilot studies, where a significant decrease in {beta} from a value of approximately 3.1 in the unprocessed images to between about 1.1 and 1.8 in the subtracted images was

  19. Anatomical noise in contrast-enhanced digital mammography. Part I. Single-energy imaging.

    PubMed

    Hill, Melissa L; Mainprize, James G; Carton, Ann-Katherine; Muller, Serge; Ebrahimi, Mehran; Jong, Roberta A; Dromain, Clarisse; Yaffe, Martin J

    2013-05-01

    The use of an intravenously injected iodinated contrast agent could help increase the sensitivity of digital mammography by adding information on tumor angiogenesis. Two approaches have been made for clinical implementation of contrast-enhanced digital mammography (CEDM), namely, single-energy (SE) and dual-energy (DE) imaging. In each technique, pairs of mammograms are acquired, which are then subtracted with the intent to cancel the appearance of healthy breast tissue to permit sensitive detection and specific characterization of lesions. Patterns of contrast agent uptake in the healthy parenchyma, and uncanceled signal from background tissue create a "clutter" that can mask or mimic an enhancing lesion. This type of "anatomical noise" is often the limiting factor in lesion detection tasks, and thus, noise quantification may be useful for cascaded systems analysis of CEDM and for phantom development. In this work, the authors characterize the anatomical noise in CEDM clinical images and the authors evaluate the influence of the x-ray energy used for acquisition, the presence of iodine in the breast, and the timing of imaging postcontrast administration on anatomical noise. The results are presented in a two-part report, with SE CEDM described here, and DE CEDM in Part II. A power law is used to model anatomical noise in CEDM images. The exponent, β, which describes the anatomical structure, and the constant α, which represents the magnitude of the noise, are determined from Wiener spectra (WS) measurements on images. A total of 42 SE CEDM cases from two previous clinical pilot studies are assessed. The parameters α and β are measured both from unprocessed images and from subtracted images. Consistent results were found between the two SE CEDM pilot studies, where a significant decrease in β from a value of approximately 3.1 in the unprocessed images to between about 1.1 and 1.8 in the subtracted images was observed. Increasing the x-ray energy from that used

  20. An improved dark-object subtraction technique for atmospheric scattering correction of multispectral data

    USGS Publications Warehouse

    Chavez, P.S.

    1988-01-01

    Digital analysis of remotely sensed data has become an important component of many earth-science studies. These data are often processed through a set of preprocessing or "clean-up" routines that includes a correction for atmospheric scattering, often called haze. Various methods to correct or remove the additive haze component have been developed, including the widely used dark-object subtraction technique. A problem with most of these methods is that the haze values for each spectral band are selected independently. This can create problems because atmospheric scattering is highly wavelength-dependent in the visible part of the electromagnetic spectrum and the scattering values are correlated with each other. Therefore, multispectral data such as from the Landsat Thematic Mapper and Multispectral Scanner must be corrected with haze values that are spectral band dependent. An improved dark-object subtraction technique is demonstrated that allows the user to select a relative atmospheric scattering model to predict the haze values for all the spectral bands from a selected starting band haze value. The improved method normalizes the predicted haze values for the different gain and offset parameters used by the imaging system. Examples of haze value differences between the old and improved methods for Thematic Mapper Bands 1, 2, 3, 4, 5, and 7 are 40.0, 13.0, 12.0, 8.0, 5.0, and 2.0 vs. 40.0, 13.2, 8.9, 4.9, 16.7, and 3.3, respectively, using a relative scattering model of a clear atmosphere. In one Landsat multispectral scanner image the haze value differences for Bands 4, 5, 6, and 7 were 30.0, 50.0, 50.0, and 40.0 for the old method vs. 30.0, 34.4, 43.6, and 6.4 for the new method using a relative scattering model of a hazy atmosphere. ?? 1988.

  1. Temporal subtraction contrast-enhanced dedicated breast CT

    NASA Astrophysics Data System (ADS)

    Gazi, Peymon M.; Aminololama-Shakeri, Shadi; Yang, Kai; Boone, John M.

    2016-09-01

    The development of a framework of deformable image registration and segmentation for the purpose of temporal subtraction contrast-enhanced breast CT is described. An iterative histogram-based two-means clustering method was used for the segmentation. Dedicated breast CT images were segmented into background (air), adipose, fibroglandular and skin components. Fibroglandular tissue was classified as either normal or contrast-enhanced then divided into tiers for the purpose of categorizing degrees of contrast enhancement. A variant of the Demons deformable registration algorithm, intensity difference adaptive Demons (IDAD), was developed to correct for the large deformation forces that stemmed from contrast enhancement. In this application, the accuracy of the proposed method was evaluated in both mathematically-simulated and physically-acquired phantom images. Clinical usage and accuracy of the temporal subtraction framework was demonstrated using contrast-enhanced breast CT datasets from five patients. Registration performance was quantified using normalized cross correlation (NCC), symmetric uncertainty coefficient, normalized mutual information (NMI), mean square error (MSE) and target registration error (TRE). The proposed method outperformed conventional affine and other Demons variations in contrast enhanced breast CT image registration. In simulation studies, IDAD exhibited improvement in MSE (0-16%), NCC (0-6%), NMI (0-13%) and TRE (0-34%) compared to the conventional Demons approaches, depending on the size and intensity of the enhancing lesion. As lesion size and contrast enhancement levels increased, so did the improvement. The drop in the correlation between the pre- and post-contrast images for the largest enhancement levels in phantom studies is less than 1.2% (150 Hounsfield units). Registration error, measured by TRE, shows only submillimeter mismatches between the concordant anatomical target points in all patient studies. The algorithm was

  2. Temporal subtraction contrast-enhanced dedicated breast CT

    PubMed Central

    Gazi, Peymon M.; Aminololama-Shakeri, Shadi; Yang, Kai; Boone, John M.

    2016-01-01

    Purpose To develop a framework of deformable image registration and segmentation for the purpose of temporal subtraction contrast-enhanced breast CT is described. Methods An iterative histogram-based two-means clustering method was used for the segmentation. Dedicated breast CT images were segmented into background (air), adipose, fibroglandular and skin components. Fibroglandular tissue was classified as either normal or contrast-enhanced then divided into tiers for the purpose of categorizing degrees of contrast enhancement. A variant of the Demons deformable registration algorithm, Intensity Difference Adaptive Demons (IDAD), was developed to correct for the large deformation forces that stemmed from contrast enhancement. In this application, the accuracy of the proposed method was evaluated in both mathematically-simulated and physically-acquired phantom images. Clinical usage and accuracy of the temporal subtraction framework was demonstrated using contrast-enhanced breast CT datasets from five patients. Registration performance was quantified using Normalized Cross Correlation (NCC), Symmetric Uncertainty Coefficient (SUC), Normalized Mutual Information (NMI), Mean Square Error (MSE) and Target Registration Error (TRE). Results The proposed method outperformed conventional affine and other Demons variations in contrast enhanced breast CT image registration. In simulation studies, IDAD exhibited improvement in MSE(0–16%), NCC (0–6%), NMI (0–13%) and TRE (0–34%) compared to the conventional Demons approaches, depending on the size and intensity of the enhancing lesion. As lesion size and contrast enhancement levels increased, so did the improvement. The drop in the correlation between the pre- and post-contrast images for the largest enhancement levels in phantom studies is less than 1.2% (150 Hounsfield units). Registration error, measured by TRE, shows only submillimeter mismatches between the concordant anatomical target points in all patient studies

  3. Non-contrast-enhanced MR angiography in critical limb ischemia: performance of quiescent-interval single-shot (QISS) and TSE-based subtraction techniques.

    PubMed

    Altaha, Mustafa A; Jaskolka, Jeffrey D; Tan, Kongteng; Rick, Manuela; Schmitt, Peter; Menezes, Ravi J; Wintersperger, Bernd J

    2017-03-01

    The aim of this study was to evaluate diagnostic performance of non-contrast-enhanced 2D quiescent-interval single-shot (QISS) and 3D turbo spin-echo (TSE)-based subtraction magnetic resonance angiography (MRA) in the assessment of peripheral arteries in patients with critical limb ischemia (CLI). Nineteen consecutive patients (74 % male, 72.8 ± 9.9 years) with CLI underwent 2D QISS and 3D TSE-based subtraction MRA at 1.5 T. Axial-overlapping QISS MRA (3 mm/2 mm; 1 × 1 mm(2)) covered from the toes to the aortic bifurcation while coronal 3D TSE-based subtraction MRA (1.3 × 1.2 × 1.3 mm(3)) was restricted to the calf only. MRA data sets (two readers) were evaluated for stenosis (≥50 %) and image quality. Results were compared with digital subtraction angiography (DSA). Two hundred and sixty-seven (267) segments were available for MRA-DSA comparison, with a prevalence of stenosis ≥50 % of 41.9 %. QISS MRA was rated as good to excellent in 79.5-96.0 % of segments without any nondiagnostic segments; 89.8-96.1 % of segments in 3D TSE-based subtraction MRA were rated as nondiagnostic or poor. QISS MRA sensitivities and specificities (segmental) were 92 % and 95 %, respectively, for reader one and 81-97 % for reader two. Due to poor image quality of 3D TSE-based subtraction MRA, diagnostic performance measures were not calculated. QISS MRA demonstrates excellent diagnostic performance and higher robustness than 3D TSE-based subtraction MRA in the challenging patient population with CLI. • QISS MRA allows reliable diagnosis of peripheral artery stenosis in critical limb ischemia. • Robustness of TSE-based subtraction MRA is limited in critical limb ischemia. • QISS MRA allows robust therapy planning in PAD patients with resting leg pain.

  4. Intravenous anaesthesia in goats: a review.

    PubMed

    Dzikiti, T Brighton

    2013-02-13

    Intravenous anaesthesia is gradually becoming popular in veterinary practice. Traditionally, general anaesthesia is induced with intravenous drugs and then maintained with inhalation agents. Inhalation anaesthetic agents cause more significant dose-dependent cardiorespiratory depression than intravenous anaesthetic drugs, creating a need to use less of the inhalation anaesthetic agents for maintenance of general anaesthesia by supplementing with intravenous anaesthesia drugs. Better still, if anaesthesia is maintained completely with intravenous anaesthetic drugs, autonomic functions remain more stable intra-operatively. Patient recovery from anaesthesia is smoother and there is less pollution of the working environment than happens with inhalation anaesthetic agents. Recently, a number of drugs with profiles (pharmacokinetic and pharmacodynamic) suitable for prolonged intravenous anaesthesia have been studied, mostly in humans and, to a certain extent, in dogs and horses. There is currently very little scientific information on total intravenous anaesthesia in goats, although, in the past few years, some scholarly scientific articles on drugs suitable for partial intravenous anaesthesia in goats have been published. This review article explored the information available on drugs that have been assessed for partial intravenous anaesthesia in goats, with the aim of promoting incorporation of these drugs into total intravenous anaesthesia protocols in clinical practice. That way, balanced anaesthesia, a technique in which drugs are included in anaesthetic protocols for specific desired effects (hypnosis, analgesia, muscle relaxation, autonomic stabilisation) may be utilised in improving the welfare of goats undergoing general anaesthesia.

  5. Fast phase retrieval in slightly off-axis digital holography

    NASA Astrophysics Data System (ADS)

    Zhong, Zhi; Bai, Hongyi; Shan, Mingguang; Zhang, Yabin; Guo, Lili

    2017-10-01

    In this study, three efficient algorithms are proposed for fast phase retrieval in slightly off-axis digital holography using spectrum cropping, spatial multiplexing, and complex encoding. In the first algorithm, the real spectral order of the subtracted hologram is filtered and cropped, and the number of pixels is decreased in the subsequent retrieval operations. In the second algorithm, two sequential subtracted holograms are digitally phase shifted and spatial multiplexed into one synthetic hologram, and thus only one inverse Fourier transformation is then required. In the third algorithm, two sequential subtracted holograms are encoded separately into the real part and the imaginary part of a complex hologram. Two cross-correlations can be used to reconstruct the phase, thereby improving the utilization of the spectrum. The three new algorithms speed up our previously proposed retrieval method with the assistance of specimen-free holograms. Our experiments demonstrated the validity and improved time requirements of the proposed methods.

  6. Analog current mode analog/digital converter

    NASA Technical Reports Server (NTRS)

    Hadidi, Khayrollah (Inventor)

    1996-01-01

    An improved subranging or comparator circuit is provided for an analog-to-digital converter. As a subranging circuit, the circuit produces a residual signal representing the difference between an analog input signal and an analog of a digital representation. This is achieved by subdividing the digital representation into two or more parts and subtracting from the analog input signal analogs of each of the individual digital portions. In another aspect of the present invention, the subranging circuit comprises two sets of differential input pairs in which the transconductance of one differential input pair is scaled relative to the transconductance of the other differential input pair. As a consequence, the same resistor string may be used for two different digital-to-analog converters of the subranging circuit.

  7. The role of bone subtraction computed tomographic angiography in determining intracranial aneurysms in non-traumatic subarachnoid hemorrhage.

    PubMed

    Kayhan, Aysegul; Koc, Osman; Keskin, Suat; Keskin, Fatih

    2014-05-01

    The presence of blood in the subarachnoid space is an acute pathology with a serious risk of death and complications. The most common etiology (approximately 80%) is intracranial aneurysm. The aim of this study was to assess the role of bone subtracted computed tomographic angiography (BSCTA), a novel and noninvasive method for determining and characterizing intracranial aneurysms. Sixty consecutive patients with clinically suspected non-traumatic subarachnoid hemorrhage (SAH) were considered to enter the study. The subtraction quality was inadequate in ten patients; thus, they were excluded, leaving 50 patients (84.4%) in the study. Bone subtracted and non-subtracted 3D images were obtained from the BSCTA raw data sets. All images obtained by digital subtraction angiography (DSA), BSCTA, and computed tomographic angiography (CTA) were evaluated for the presence or absence of an aneurysm and the location, minimal sac diameter, and neck size ratio of the aneurysm. DSA was considered as the gold standard during the evaluation of the data. Of the 50 patients who participated in this study, 11 had no aneurysms as determined by both CTA and DSA. Examination of the remaining 39 patients revealed the presence of 51 aneurysms. While 3D-CTA could not detect six aneurysms that were located in the base of the skull, 3D-BSCTA easily detected them. Moreover, five aneurysms were only partially detected by 3D-CTA. According to this data, the sensitivity of 3D-BSCTA and 3D-CTA was calculated as 98% and 86.3%, respectively; the specificity was calculated as 100% and 90.9%, respectively, per aneurysm; and the sensitivity of 100% for 3D-BSCTA and 98% for 3D-CTA was achieved by using combined images with multi-planar reconstruction (MPR) and maximum intensity projection (MIP). BSCTA detected and characterized the aneurysms as well as DSA, and BSCTA and DSA gave concordant results in detecting aneurysms. BSCTA is easily accessible, less time consuming, and most importantly, a non

  8. Digital Noise Reduction: An Overview

    PubMed Central

    Bentler, Ruth; Chiou, Li-Kuei

    2006-01-01

    Digital noise reduction schemes are being used in most hearing aids currently marketed. Unlike the earlier analog schemes, these manufacturer-specific algorithms are developed to acoustically analyze the incoming signal and alter the gain/output characteristics according to their predetermined rules. Although most are modulation-based schemes (ie, differentiating speech from noise based on temporal characteristics), spectral subtraction techniques are being applied as well. The purpose of this article is to overview these schemes in terms of their differences and similarities. PMID:16959731

  9. Intravenous Fluid Use in Athletes

    PubMed Central

    Givan, Gordon V.; Diehl, Jason J.

    2012-01-01

    Context: Time allowing, euhydration can be achieved in the vast majority of individuals by drinking and eating normal beverages and meals. Important to the competitive athlete is prevention and treatment of dehydration and exercise-associated muscle cramps, as they are linked to a decline in athletic performance. Intravenous (IV) prehydration and rehydration has been proposed as an ergogenic aid to achieve euhydration more effectively and efficiently. Evidence Acquisition: PubMed database was searched in November 2011 for all English-language articles related to IV utilization in sport using the keywords intravenous, fluid requirements, rehydration, hydration, athlete, sport, exercise, volume expansion, and performance. Results: Limited evidence exists for prehydration with IV fluids. Although anecdotal evidence does exist, at this time there are no high-level studies confirming that IV prehydration prevents dehydration or the onset of exercise-associated muscle cramps. Currently, there are no published studies describing IV fluid use during the course of an event, at intermission, or after the event as an ergogenic aid. Conclusion: The use of IV fluid may be beneficial for a subset of fluid-sensitive athletes; this should be reserved for high-level athletes with strong histories of symptoms in well-monitored settings. Volume expanders may also be beneficial for some athletes. IV fluids and plasma binders are not allowed in World Anti-Doping Agency–governed competitions. Routine IV therapy cannot be recommended as best practice for the majority of athletes. PMID:23016105

  10. Intravenous injections in neonatal mice.

    PubMed

    Gombash Lampe, Sara E; Kaspar, Brian K; Foust, Kevin D

    2014-11-11

    Intravenous injection is a clinically applicable manner to deliver therapeutics. For adult rodents and larger animals, intravenous injections are technically feasible and routine. However, some mouse models can have early onset of disease with a rapid progression that makes administration of potential therapies difficult. The temporal (or facial) vein is just anterior to the ear bud in mice and is clearly visible for the first two days after birth on either side of the head using a dissecting microscope. During this window, the temporal vein can be injected with volumes up to 50 μl. The injection is safe and well tolerated by both the pups and the dams. A typical injection procedure is completed within 1-2 min, after which the pup is returned to the home cage. By the third postnatal day the vein is difficult to visualize and the injection procedure becomes technically unreliable. This technique has been used for delivery of adeno-associated virus (AAV) vectors, which in turn can provide almost body-wide, stable transgene expression for the life of the animal depending on the viral serotype chosen.

  11. Intravenous Injections in Neonatal Mice

    PubMed Central

    Gombash Lampe, Sara E.; Kaspar, Brian K.; Foust, Kevin D.

    2014-01-01

    Intravenous injection is a clinically applicable manner to deliver therapeutics. For adult rodents and larger animals, intravenous injections are technically feasible and routine. However, some mouse models can have early onset of disease with a rapid progression that makes administration of potential therapies difficult. The temporal (or facial) vein is just anterior to the ear bud in mice and is clearly visible for the first two days after birth on either side of the head using a dissecting microscope. During this window, the temporal vein can be injected with volumes up to 50 μl. The injection is safe and well tolerated by both the pups and the dams. A typical injection procedure is completed within 1-2 min, after which the pup is returned to the home cage. By the third postnatal day the vein is difficult to visualize and the injection procedure becomes technically unreliable. This technique has been used for delivery of adeno-associated virus (AAV) vectors, which in turn can provide almost body-wide, stable transgene expression for the life of the animal depending on the viral serotype chosen. PMID:25407048

  12. Digital Libraries.

    ERIC Educational Resources Information Center

    Fox, Edward A.; Urs, Shalini R.

    2002-01-01

    Provides an overview of digital libraries research, practice, and literature. Highlights include new technologies; redefining roles; historical background; trends; creating digital content, including conversion; metadata; organizing digital resources; services; access; information retrieval; searching; natural language processing; visualization;…

  13. Digital Libraries.

    ERIC Educational Resources Information Center

    Fox, Edward A.; Urs, Shalini R.

    2002-01-01

    Provides an overview of digital libraries research, practice, and literature. Highlights include new technologies; redefining roles; historical background; trends; creating digital content, including conversion; metadata; organizing digital resources; services; access; information retrieval; searching; natural language processing; visualization;…

  14. Contrast-Medium-Enhanced Digital Mammography: Contrast vs. Iodine Concentration Phantom Calibration

    SciTech Connect

    Rosado-Mendez, I.; Brandan, M. E.; Villasenor, Y.; Benitez-Bribiesca, L.

    2008-08-11

    This work deals with the application of the contrast-medium-enhanced digital subtraction mammography technique in order to calibrate the contrast level in subtracted phantom images as function of iodine concentration to perform dynamic studies of the contrast-medium uptake in the breast. Previously optimized dual-energy temporal subtraction modalities were used (a) to determine radiological parameters for a dynamic clinical study composed of 1 mask+3 post-contrast images limiting the total mean glandular dose to 2.5 mGy, and (b) to perform a contrast vs iodine concentration calibration using a custom-made phantom. Calculated exposure values were applied using a commercial full-field digital mammography unit. Contrast in subtracted phantom images (one mask and one post-CM) is linear as function of iodine concentration, although the sensitivity (contrast per iodine concentration) decreases beyond 8 mg/mL. This calibration seems to apply only to thin and normal thickness breasts.

  15. Suppressive Subtractive Hybridization Detects Extensive Genomic Diversity in Thermotoga maritima

    PubMed Central

    Nesbø, Camilla L.; Nelson, Karen E.; Doolittle, W. Ford

    2002-01-01

    Comparisons between genomes of closely related bacteria often show large variations in gene content, even between strains of the same species. Such studies have focused mainly on pathogens; here, we examined Thermotoga maritima, a free-living hyperthermophilic bacterium, by using suppressive subtractive hybridization. The genome sequence of T. maritima MSB8 is available, and DNA from this strain served as a reference to obtain strain-specific sequences from Thermotoga sp. strain RQ2, a very close relative (∼96% identity for orthologous protein-coding genes, 99.7% identity in the small-subunit rRNA sequence). Four hundred twenty-six RQ2 subtractive clones were sequenced. One hundred sixty-six had no DNA match in the MSB8 genome. These differential clones comprise, in sum, 48 kb of RQ2-specific DNA and match 72 genes in the GenBank database. From the number of identical clones, we estimated that RQ2 contains 350 to 400 genes not found in MSB8. Assuming a similar genome size, this corresponds to 20% of the RQ2 genome. A large proportion of the RQ2-specific genes were predicted to be involved in sugar transport and polysaccharide degradation, suggesting that polysaccharides are more important as nutrients for this strain than for MSB8. Several clones encode proteins involved in the production of surface polysaccharides. RQ2 encodes multiple subunits of a V-type ATPase, while MSB8 possesses only an F-type ATPase. Moreover, an RQ2-specific MutS homolog was found among the subtractive clones and appears to belong to a third novel archaeal type MutS lineage. Southern blot analyses showed that some of the RQ2 differential sequences are found in some other members of the order Thermotogales, but the distribution of these variable genes is patchy, suggesting frequent lateral gene transfer within the group. PMID:12142418

  16. Adding and subtracting vectors: The problem with the arrow representation

    NASA Astrophysics Data System (ADS)

    Heckler, Andrew F.; Scaife, Thomas M.

    2015-06-01

    A small number of studies have investigated student understanding of vector addition and subtraction in generic or introductory physics contexts, but in almost all cases the questions posed were in the vector arrow representation. In a series of experiments involving over 1000 students and several semesters, we investigated student understanding of vector addition and subtraction in both the arrow and algebraic notation (using i ^, j ^, k ^) in generic mathematical and physics contexts. First, we replicated a number of previous findings of student difficulties in the arrow format and discovered several additional difficulties, including the finding that different relative arrow orientations can prompt different solution paths and different kinds of mistakes, which suggests that students need to practice with a variety of relative orientations. Most importantly, we found that average performance in the i j k format was typically excellent and often much better than performance in the arrow format in either the generic or physics contexts. Further, while we find that the arrow format tends to prompt students to a more physically intuitive solution path, we also find that, when prompted, student solutions in the i j k format also display significant physical insights into the problem. We also find a hierarchy in correct answering between the two formats, with correct answering in the i j k format being more fundamental than for the arrow format. Overall, the results suggest that many student difficulties with these simple vector problems lie with the arrow representation itself. For instruction, these results imply that introducing the i j k notation (or some equivalent) with the arrow notation concurrently may be a very useful way to improve student performance as well as help students to learn physics concepts involving vector addition and subtraction.

  17. Maternal MCG Interference Cancellation Using Splined Independent Component Subtraction

    PubMed Central

    Yu, Suhong

    2011-01-01

    Signal distortion is commonly observed when using independent component analysis (ICA) to remove maternal cardiac interference from the fetal magnetocardiogram. This can be seen even in the most conservative case where only the independent components dominated by maternal interference are subtracted from the raw signal, a procedure we refer to as independent component subtraction (ICS). Distortion occurs when the subspaces of the fetal and maternal signals have appreciable overlap. To overcome this problem, we employed splining to remove the fetal signal from the maternal source component. The maternal source components were downsampled and then interpolated to their original sampling rate using a cubic spline. A key aspect of the splining procedure is that the maternal QRS complexes are downsampled much less than the rest of the maternal signal so that they are not distorted, despite their higher bandwidth. The splined maternal source components were projected back onto the magnetic field measurement space and then subtracted from the raw signal. The method was evaluated using data from 24 subjects. We compared the results of conventional, i.e., unsplined, ICS with our method, splined ICS, using matched filtering as a reference. Correlation and subjective assessment of the P-wave and QRS complex were used to assess the performance. Using ICS, we found that the P-wave was adversely affected in 7 of 24 (29%) subjects, all having correlations less than 0.8. Splined ICS showed negligible distortion and improved the signal fidelity to some extent in all subjects. We also demonstrated that maternal T-wave interference could be problematic when the fetal and maternal heartbeats were synchronous. In these instances, splined ICS was more effective than matched filtering. PMID:21712157

  18. Intravenous nutrition during a twin pregnancy.

    PubMed

    Karamatsu, J T; Boyd, A T; Cooke, J; Vinall, P S; McMahon, M J

    1987-01-01

    A case is reported of a woman in the third trimester of a twin pregnancy who required intravenous nutrition because of inadequate absorption of nutrients due to a jejunoileal bypass. Weight gain was poor, and there was evidence of intrauterine growth retardation before commencement of intravenous feeding. She received overnight intravenous nutrition for 6 weeks and gained weight with ultrasound evidence of fetal growth. During the 33rd week of gestation, she was delivered of healthy twin males who were at appropriate birth weights and development for their age of gestation. The considerations in intravenous nutrition for a twin pregnancy after jejunoileal bypass are discussed.

  19. Spondylolisthesis following a pedicle subtraction osteotomy. Case report.

    PubMed

    Upadhyaya, Cheerag D; Berven, Sigurd; Mumaneni, Praveen V

    2010-03-01

    Pedicle subtraction osteotomy (PSO) is a powerful technique for correcting a fixed sagittal plane deformity. The authors report the case of a 51-year-old man with a history of multiple prior lumbar operations, flat-back syndrome, thoracic kyphosis, and radiculopathy, who underwent deformity correction surgery with T3-S1 pedicle screw fixation and L-3 PSO. Progressive spondylolisthesis of the PSO segment associated with rod fracture then developed. The patient subsequently underwent anterior and posterior revision surgery. This case is a rare instance of spondylolisthesis following PSO.

  20. WFPC2 photometry from subtraction of TinyTim PSFs

    NASA Technical Reports Server (NTRS)

    Remy, M.; Surdej, J.; Baggett, S.; Wiggs, M.

    1997-01-01

    Based upon the subtraction of TinyTim Point Spread Function (PSFs) from Principle Component Image (PC1) point-like objects, a method has been developed to determine the optimal values for the telescope jitter and the Z4 relative focus during calibration or science observations. Using these jitter and focus values, an optimal TinyTim PSF, computed over a resampled grid, is then iteratively fitted to the object, yielding an improvement in the PSF centering, more accurate photometric results and a better detection of underlying structures. Preliminary results seem to indicate that appropriate synthetic TinyTim PSFs perform as well as observed PSFs.

  1. Additive and subtractive scrambling in optional randomized response modeling.

    PubMed

    Hussain, Zawar; Al-Sobhi, Mashail M; Al-Zahrani, Bander

    2014-01-01

    This article considers unbiased estimation of mean, variance and sensitivity level of a sensitive variable via scrambled response modeling. In particular, we focus on estimation of the mean. The idea of using additive and subtractive scrambling has been suggested under a recent scrambled response model. Whether it is estimation of mean, variance or sensitivity level, the proposed scheme of estimation is shown relatively more efficient than that recent model. As far as the estimation of mean is concerned, the proposed estimators perform relatively better than the estimators based on recent additive scrambling models. Relative efficiency comparisons are also made in order to highlight the performance of proposed estimators under suggested scrambling technique.

  2. Intermediate Palomar Transient Factory: Realtime Image Subtraction Pipeline

    SciTech Connect

    Cao, Yi; Nugent, Peter E.; Kasliwal, Mansi M.

    2016-09-28

    A fast-turnaround pipeline for realtime data reduction plays an essential role in discovering and permitting followup observations to young supernovae and fast-evolving transients in modern time-domain surveys. In this paper, we present the realtime image subtraction pipeline in the intermediate Palomar Transient Factory. By using highperformance computing, efficient databases, and machine-learning algorithms, this pipeline manages to reliably deliver transient candidates within 10 minutes of images being taken. Our experience in using high-performance computing resources to process big data in astronomy serves as a trailblazer to dealing with data from large-scale time-domain facilities in the near future.

  3. Peripheral NN scattering from subtractive renormalization of chiral interactions

    NASA Astrophysics Data System (ADS)

    Batista, E. F.; Szpigel, S.; Timóteo, V. S.

    2014-11-01

    We apply five subtractions in the Lippman-Schwinger (LS) equation in order to perform a non-perturbative renormalization of chiral N3LO nucleon-nucleon interactions. Here we compute the phase shifts for the uncoupled peripheral waves at renormalization scales between 0.1 fm-1 and 1 fm-1. In this range, the results are scale invariant and provide an overall good agreement with the Nijmegen partial wave analysis up to at least Elab = 150 MeV, with a cutoff at Λ = 30 fm-1.

  4. Addition and subtraction by students with Down syndrome

    NASA Astrophysics Data System (ADS)

    Noda Herrera, Aurelia; Bruno, Alicia; González, Carina; Moreno, Lorenzo; Sanabria, Hilda

    2011-01-01

    We present a research report on addition and subtraction conducted with Down syndrome students between the ages of 12 and 31. We interviewed a group of students with Down syndrome who executed algorithms and solved problems using specific materials and paper and pencil. The results show that students with Down syndrome progress through the same procedural levels as those without disabilities though they have difficulties in reaching the most abstract level (numerical facts). The use of fingers or concrete representations (balls) appears as a fundamental process among these students. As for errors, these vary widely depending on the students, and can be attributed mostly to an incomplete knowledge of the decimal number system.

  5. Peripheral NN scattering from subtractive renormalization of chiral interactions

    SciTech Connect

    Batista, E. F.; Szpigel, S.; Timóteo, V. S.

    2014-11-11

    We apply five subtractions in the Lippman-Schwinger (LS) equation in order to perform a non-perturbative renormalization of chiral N3LO nucleon-nucleon interactions. Here we compute the phase shifts for the uncoupled peripheral waves at renormalization scales between 0.1 fm{sup −1} and 1 fm{sup −1}. In this range, the results are scale invariant and provide an overall good agreement with the Nijmegen partial wave analysis up to at least E{sub lab} = 150 MeV, with a cutoff at Λ = 30 fm{sup −1}.

  6. Development of a voxel-matching technique for substantial reduction of subtraction artifacts in temporal subtraction images obtained from thoracic MDCT.

    PubMed

    Itai, Yoshinori; Kim, Hyoungseop; Ishikawa, Seiji; Katsuragawa, Shigehiko; Doi, Kunio

    2010-02-01

    A temporal subtraction image, which is obtained by subtraction of a previous image from a current one, can be used for enhancing interval changes (such as formation of new lesions and changes in existing abnormalities) on medical images by removing most of the normal structures. However, subtraction artifacts are commonly included in temporal subtraction images obtained from thoracic computed tomography and thus tend to reduce its effectiveness in the detection of pulmonary nodules. In this study, we developed a new method for substantially removing the artifacts on temporal subtraction images of lungs obtained from multiple-detector computed tomography (MDCT) by using a voxel-matching technique. Our new method was examined on 20 clinical cases with MDCT images. With this technique, the voxel value in a warped (or nonwarped) previous image is replaced by a voxel value within a kernel, such as a small cube centered at a given location, which would be closest (identical or nearly equal) to the voxel value in the corresponding location in the current image. With the voxel-matching technique, the correspondence not only between the structures but also between the voxel values in the current and the previous images is determined. To evaluate the usefulness of the voxel-matching technique for removal of subtraction artifacts, the magnitude of artifacts remaining in the temporal subtraction images was examined by use of the full width at half maximum and the sum of a histogram of voxel values, which may indicate the average contrast and the total amount, respectively, of subtraction artifacts. With our new method, subtraction artifacts due to normal structures such as blood vessels were substantially removed on temporal subtraction images. This computerized method can enhance lung nodules on chest MDCT images without disturbing misregistration artifacts.

  7. Home intravenous therapy: Part I--Issues.

    PubMed

    McAbee, R R; Grupp, K; Horn, B

    1991-01-01

    Concerns related to providing home intravenous therapy were among the top ten clinical problems identified by Northwest Medicare-certified home care agencies in a 1986 survey. This paper addresses issues related to home intravenous therapy and provides lists of resources for the development of home intravenous therapy programs. Part I of the paper covers concerns related to intravenous therapy as expressed by home care agencies in the Northwest and synthesized the literature about home intravenous therapies. Survey results are presented, followed by a discussion of client and caregiver concerns. These include: discharge planning, client admission criteria and client and caregiver education. Standards, staffing, and staff education issues are discussed followed by sections on economics, marketing regulations and legal and ethical concerns. Finally, there is a discussion of issues related to specific types of intravenous therapies: parenteral nutrition, antibiotic therapy; chemotherapy; blood and blood component therapy and other less frequently used types of intravenous therapies. Each therapy is discussed with regard to complications, client and caregiver instruction and financial considerations. Part II of the paper is a resource guide which lists resources that agencies may use to develop a home intravenous therapy program. In the first section, national organizations and journals and books concerned with intravenous therapy are listed as well as journal articles, guidelines and guidebooks and client and provider educational materials. National and regional product and service representatives of intravenous therapy related companies are also listed. In the second section, addresses for the State Boards of Nursing are given for Alaska, Idaho, Montana, Oregon and Washington. Each state section includes a list of those agencies who indicated in the 1988 survey that they would be willing to share materials. In addition, product and service vendors of intravenous

  8. Digital Subtraction Angiography is Superior to Magnetic Resonance Angiography in Diagnosis of Cerebral Arteriovenous Malformation.

    PubMed

    Chowdhury, A H; Ghose, S K; Mohammad, Q D; Habib, M; Khan, S U; Rahman, K M

    2015-04-01

    This study was carried out to compare MRA and DSA in diagnosis of cerebral AVM. It was a retrospective observational study conducted in the Department of Neurology Dhaka Medical College Hospital (DMCH), Dhaka during the period of January 2010 to December 2010. Thirty patients with haemorrhagic stroke age ranging from 13 to 65 years were selected on the basis of inclusion and exclusion criteria as the study sample. MRA and DSA were done in all the selected patients. The mean age of the patients of haemorrhagic stroke was 30.3 ± 14.3 years and male female ratio was 2.7:1. Regarding the venous drainage of AVM 13 and 12 were superficial and deep respectively, and evaluated 100% by MRA. In the diagnosis of cerebral AVM nidus size S1: <3 and S2: 3-6 cm sensitivity was 100% but accuracy was 100% and 73.3% respectively. DSA was 100% sensitive in the diagnosis of superficial and deep venous drainage AVM. Regarding the eloquence of brain area 15 had no eloquence by both MRA and DSA and identification of eloquence of brain area sensitivity was 73.3% and accuracy was 86.7%. The main feeding vessels was found (22, 73.3%) in both DSA and MRA findings. Distal vessels was seen (8, 26.7%) in DSA but not seen in MRA findings. Intranidal aneurysm and Angiopathic AVM were seen in 3(10.0%) and 4(13.3%) respectively in DSA. This study was carried out to diagnose the patients presented with cerebral AVM by MRA and DSA. MRA could not be evaluated flow status of AVM, distal feeding arteries, intranidal aneurysm and angiopathic AVM which could be detected by DSA. So, DSA is superior to MRA in diagnosis of cerebral AVM.

  9. Digital Subtraction Fluoroscopy to Enhance Visualization During Uterine Fibroid Embolization: A Technical Note

    SciTech Connect

    Andrews, Robert T. Binkert, Christoph A.

    2003-06-15

    We describe a simple but underutilized technique for improving visualization during transcatheter embolization using particulate agents. The technique is of distinct utility in uterine fibroid embolization, during which non-target embolization can be of particular clinical significance.

  10. Temporal Subtraction of Digital Breast Tomosynthesis Images for Improved Mass Detection

    DTIC Science & Technology

    2008-10-01

    K. Fishman and B. M. W. Tsui, "Development of a computer-generated model for the coronary arterial tree based on multislice CT and morphometric data...mathematical models based on geometric primitives8-22. Bakic et al created synthetic x-ray mammograms using a 3D simulated breast tissue model consisting of...utilized a combination of voxel matrices and geometric primitives to create a breast phantom that includes the breast surface, the duct system, and

  11. Temporal Subtraction of Digital Breast Tomosynthesis Images for Improved Mass Detection

    DTIC Science & Technology

    2009-11-01

    imaging using two distinct methods7-15: mathematically based models defined by geometric primitives and voxelized models derived from real human...trees to complete them. We also plan to add further detail by defining the Cooper’s ligaments using geometrical NURBS surfaces. Realistic...generated model for the coronary arterial tree based on multislice CT and morphometric data," Medical Imaging 2006: Physics of Medical Imaging 6142

  12. Volumetric limiting spatial resolution analysis of four dimensional digital subtraction angiography (4D-DSA)

    NASA Astrophysics Data System (ADS)

    Davis, Brian; Oberstar, Erick; Royalty, Kevin; Schafer, Sebastian; Strother, Charles; Mistretta, Charles

    2015-03-01

    Static C-Arm CT 3D FDK baseline reconstructions (3D-DSA) are unable to provide temporal information to radiologists. 4D-DSA provides a time series of 3D volumes implementing a constrained image, thresholded 3D-DSA, reconstruction utilizing temporal dynamics in the 2D projections. Volumetric limiting spatial resolution (VLSR) of 4DDSA is quantified and compared to a 3D-DSA reconstruction using the same 3D-DSA parameters. Investigated were the effects of varying over significant ranges the 4D-DSA parameters of 2D blurring kernel size applied to the projection and threshold applied to the 3D-DSA when generating the constraining image of a scanned phantom (SPH) and an electronic phantom (EPH). The SPH consisted of a 76 micron tungsten wire encased in a 47 mm O.D. plastic radially concentric thin walled support structure. An 8-second/248-frame/198° scan protocol acquired the raw projection data. VLSR was determined from averaged MTF curves generated from each 2D transverse slice of every (248) 4D temporal frame (3D). 4D results for SPH and EPH were compared to the 3D-DSA. Analysis of the 3D-DSA resulted in a VLSR of 2.28 and 1.69 lp/mm for the EPH and SPH respectively. Kernel (2D) sizes of either 10x10 or 20x20 pixels with a threshold of 10% of the 3D-DSA as a constraining image provided 4D-DSA VLSR nearest to the 3D-DSA. 4D-DSA algorithms yielded 2.21 and 1.67 lp/mm with a percent error of 3.1% and 1.2% for the EPH and SPH respectively as compared to the 3D-DSA. This research indicates 4D-DSA is capable of retaining the resolution of the 3D-DSA.

  13. Comparative evaluation of 64-slice CT angiography and digital subtraction angiography in assessing the cervicocranial vasculature.

    PubMed

    Klingebiel, Randolf; Kentenich, Max; Bauknecht, Hans-Christian; Masuhr, Florian; Siebert, Eberhard; Busch, Markus; Bohner, Georg

    2008-01-01

    Noninvasive 64-slice computed tomography angiography (64-MSCTA) closely approximates conventional catheter angiography (DSA) in terms of detail resolution. Retrospective evaluation of cervicocranial (cc) 64-MSCTA in comparison with DSA in patients with presumptive cc vascular disorders. Twenty-four 64-MSCTA studies (32 mm detector width, slice thickness 0.5 mm, 120 kv, 150 mAs, pitch 0.75) of patients with presumptive cc vascular pathology (13 men, 11 women, mean age 38.3 +/- 11.3 yrs, range 19-54 yrs) were assessed in comparison with DSA studies without abnormal findings in age-matched patients (11 men, 13 women, mean age 39.7 +/- 11.9 yrs, range 18-54 yrs). Study readings were performed in a blinded manner by two neuroradiologists with respect to image quality and assessibility of various cc vascular segments by using a five-point scale. Radiation exposure was calculated for 64-MSCTA. Each reader assessed 384/528 different vessel segments (64-MSCTA/DSA). Superior image quality was attributed to DSA with respect to the C1 ICA-C6 ICA, A3 ACA, and P3 PCA segments as well the AICA and SCA. 64-MSCTA was scored superior for C7 ICA and V4 VA segments. A significantly increased number ofnonassessable V2- and V3 VA segments in DSA studies was noted. The effective dose for 64-MSCTA amounted to 2.2 mSv. 64-MSCTA provides near-equivalent diagnostic information of the cc vasculature as compared with DSA. According to our results, DSA should be considered primarily when peripheral vessels (A3/P3) or ICA segments close to the skull base (C2-5) are of interest, such as in primary angiitis or stenoocclusive ICA disease, respectively.

  14. Active double contour for segmentation of vessels in digital subtraction angiography

    NASA Astrophysics Data System (ADS)

    Hinz, Manfred; Toennies, Klaus D.; Grohmann, Markus; Pohle, Regina

    2001-07-01

    Successful extraction of small vessels in DSA images requires inclusion of prior knowledge about vessel characteristics. We developed an active double contour (ADC) that uses a vessel template as a model. The template is fitted to the vessel using an adapted ziplock snake approach based on two user-specified end locations. The external energy terms of the ADC describe an ideal vessel with projections changing slowly their course, width and intensity. A backtracking ability was added that enables overturning local decisions that may cause the ziplock snake to be trapped in a local minimum. This is because the optimization of the ADC is carried out locally. If the total energy indicates such case, vessel boundary points are removed and the ziplock process starts again without this location in its actual configuration. The method was tested on artificial data and DSA data. The former showed good agreement between artificial vessel and segmented structure at an SNR as low as 1.5:1. Results from DSA data showed robustness of the method in the presence of noise and its ability to cope with branchings and crossings. The backtracking was found to overcome local minima of the energy function at artefacts, vessel crossings and in regions of low SNR.

  15. Fast Image Subtraction Using Multi-cores and GPUs

    NASA Astrophysics Data System (ADS)

    Hartung, Steven; Shukla, H.

    2013-01-01

    Many important image processing techniques in astronomy require a massive number of computations per pixel. Among them is an image differencing technique known as Optimal Image Subtraction (OIS), which is very useful for detecting and characterizing transient phenomena. Like many image processing routines, OIS computations increase proportionally with the number of pixels being processed, and the number of pixels in need of processing is increasing rapidly. Utilizing many-core graphical processing unit (GPU) technology in a hybrid conjunction with multi-core CPU and computer clustering technologies, this work presents a new astronomy image processing pipeline architecture. The chosen OIS implementation focuses on the 2nd order spatially-varying kernel with the Dirac delta function basis, a powerful image differencing method that has seen limited deployment in part because of the heavy computational burden. This tool can process standard image calibration and OIS differencing in a fashion that is scalable with the increasing data volume. It employs several parallel processing technologies in a hierarchical fashion in order to best utilize each of their strengths. The Linux/Unix based application can operate on a single computer, or on an MPI configured cluster, with or without GPU hardware. With GPU hardware available, even low-cost commercial video cards, the OIS convolution and subtraction times for large images can be accelerated by up to three orders of magnitude.

  16. Background Subtraction Based on Three-Dimensional Discrete Wavelet Transform.

    PubMed

    Han, Guang; Wang, Jinkuan; Cai, Xi

    2016-03-30

    Background subtraction without a separate training phase has become a critical task, because a sufficiently long and clean training sequence is usually unavailable, and people generally thirst for immediate detection results from the first frame of a video. Without a training phase, we propose a background subtraction method based on three-dimensional (3D) discrete wavelet transform (DWT). Static backgrounds with few variations along the time axis are characterized by intensity temporal consistency in the 3D space-time domain and, hence, correspond to low-frequency components in the 3D frequency domain. Enlightened by this, we eliminate low-frequency components that correspond to static backgrounds using the 3D DWT in order to extract moving objects. Owing to the multiscale analysis property of the 3D DWT, the elimination of low-frequency components in sub-bands of the 3D DWT is equivalent to performing a pyramidal 3D filter. This 3D filter brings advantages to our method in reserving the inner parts of detected objects and reducing the ringing around object boundaries. Moreover, we make use of wavelet shrinkage to remove disturbance of intensity temporal consistency and introduce an adaptive threshold based on the entropy of the histogram to obtain optimal detection results. Experimental results show that our method works effectively in situations lacking training opportunities and outperforms several popular techniques.

  17. Nonclassicality and decoherence of photon-subtracted squeezed states

    NASA Astrophysics Data System (ADS)

    Biswas, Asoka; Agarwal, Girish S.

    2007-03-01

    Single-photon subtracted squeezed vacuum states are equivalent to Schrodinger kitten states and show non-Gaussian nature in phase space. Such states are useful in entanglement distillation, loophole-free test of Bell's inequality, and quantum computing. We discuss nonclassical properties of these states in terms of the sub-Poissonian statistics and the negativity of the Wigner function. We derive a compact expression for the Wigner function from which we find the region of phase space where Wigner function is negative. We find an upper bound on the squeezing parameter for the state to exhibit sub-Poissonian statistics. We then study the effect of decoherence on the single-photon subtracted squeezed states. We present results for two different models of decoherence, viz. amplitude decay model and the phase diffusion model. In each case we give analytical results for the time evolution of the state. We discuss the loss of nonclassicality as a result of decoherence. We show through the study of their phase-space properties how these states decay to vacuum due to the decay of photons. We show that phase damping leads to very slow decoherence than the photon-number decay and the state remains nonclassical at long times.

  18. Robust baseline subtraction for ultrasonic full wavefield analysis

    NASA Astrophysics Data System (ADS)

    Alguri, K. Supreet; Michaels, Jennifer E.; Harley, Joel B.

    2017-02-01

    Full wavefield analysis is used to study and characterize the interaction between waves and structural damage. Yet, as wavefields are measured and as damage evolves in a structure, environmental and operational variations can significantly affect wave propagation. Several approaches, including time-stretching and optimal baseline selection methods, can reduce variations, but these methods are often limited to specific effects, are ineffective for large environmental variations, or require an impractical number of prior baseline measurements. This paper presents a robust methodology for subtracting wavefields and isolating wave-damage interactions. The method is based on dictionary learning. It is robust to multiple types of environmental and operational variations and requires only one initial baseline. We learn the dictionary, which describes wave propagation for a particular wavefield, based on multiple frequencies of a baseline wavefield. We then use the dictionary and sparse regression to create new baselines for measurements with different environmental and operational conditions. The new baseline is then subtracted from the new wavefield to isolate damage wavefield.

  19. Background Subtraction Based on Three-Dimensional Discrete Wavelet Transform

    PubMed Central

    Han, Guang; Wang, Jinkuan; Cai, Xi

    2016-01-01

    Background subtraction without a separate training phase has become a critical task, because a sufficiently long and clean training sequence is usually unavailable, and people generally thirst for immediate detection results from the first frame of a video. Without a training phase, we propose a background subtraction method based on three-dimensional (3D) discrete wavelet transform (DWT). Static backgrounds with few variations along the time axis are characterized by intensity temporal consistency in the 3D space-time domain and, hence, correspond to low-frequency components in the 3D frequency domain. Enlightened by this, we eliminate low-frequency components that correspond to static backgrounds using the 3D DWT in order to extract moving objects. Owing to the multiscale analysis property of the 3D DWT, the elimination of low-frequency components in sub-bands of the 3D DWT is equivalent to performing a pyramidal 3D filter. This 3D filter brings advantages to our method in reserving the inner parts of detected objects and reducing the ringing around object boundaries. Moreover, we make use of wavelet shrinkage to remove disturbance of intensity temporal consistency and introduce an adaptive threshold based on the entropy of the histogram to obtain optimal detection results. Experimental results show that our method works effectively in situations lacking training opportunities and outperforms several popular techniques. PMID:27043570

  20. Infinite S-expansion with ideal subtraction and some applications

    NASA Astrophysics Data System (ADS)

    Peñafiel, D. M.; Ravera, L.

    2017-08-01

    According to the literature, the S-expansion procedure involving a finite semigroup is valid no matter what the structure of the original Lie (super)algebra is; however, when something about the structure of the starting (super)algebra is known and when certain particular conditions are met, the S-expansion method (with its features of resonance and reduction) is able not only to lead to several kinds of expanded (super)algebras but also to reproduce the effects of the standard as well as the generalized Inönü-Wigner contraction. In the present paper, we propose a new prescription for S-expansion, involving an infinite abelian semigroup S(∞ ) and the subtraction of an infinite ideal subalgebra. We show that the subtraction of the infinite ideal subalgebra corresponds to a reduction. Our approach is a generalization of the finite S-expansion procedure presented in the literature, and it offers an alternative view of the generalized Inönü-Wigner contraction. We then show how to write the invariant tensors of the target (super)algebras in terms of those of the starting ones in the infinite S-expansion context presented in this work. We also give some interesting examples of application on algebras and superalgebras.

  1. Digital Preservation.

    ERIC Educational Resources Information Center

    Yakel, Elizabeth

    2001-01-01

    Reviews research on digital preservation issues, including born-digital and digitally recreated documents. Discusses electronic records research; metadata and other standards; electronic mail; Web-based documents; moving images media; selection of materials for digitization, including primary sources; administrative issues; media stability…

  2. Single dose intravenous propacetamol or intravenous paracetamol for postoperative pain.

    PubMed

    Tzortzopoulou, Aikaterini; McNicol, Ewan D; Cepeda, M Soledad; Francia, Marie Belle D; Farhat, Tamman; Schumann, Roman

    2011-10-05

    Paracetamol (acetaminophen) is the most commonly prescribed analgesic for the treatment of acute pain. It may be administered orally or intravenously. The efficacy and safety of intravenous (IV) formulations of paracetamol, IV paracetamol and IV propacetamol, compared with placebo and other analgesics, is unclear. To assess the efficacy and safety of IV formulations of paracetamol for treatment of postoperative pain in both adults and children. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 2), MEDLINE (1950 to May 2010), EMBASE (1980 to 2010, Week 18), LILACS (1992 to May 2010) and reference lists of retrieved articles. Randomized, double-blind, placebo- or active-controlled single dose clinical trials of IV propacetamol or IV paracetamol for acute postoperative pain in adults or children. Two review authors independently assessed the risk of bias and extracted data. We contacted study authors for additional information. We collected adverse event information from the studies. Thirty-six studies (3896 participants) were included. Thirty-seven percent of participants receiving IV propacetamol/paracetamol experienced at least 50% pain relief over four hours compared with 16% of those receiving placebo (number needed to treat to benefit (NNT = 4.0; 95% confidence interval 3.5 to 4.8). The proportion of participants in IV propacetamol/paracetamol groups experiencing at least 50% pain relief diminished over six hours, as reflected in a higher NNT of 5.3 (4.2 to 6.7). Participants receiving IV propacetamol/paracetamol required 30% less opioid over four hours than those receiving placebo. However, this did not translate to a reduction in opioid-induced adverse events.Meta-analysis of efficacy comparisons between IV propacetamol/paracetamol and active comparators (opioids or nonsteroidal anti-inflammatories (NSAIDs)) were either not statistically significant, not clinically significant, or both.Adverse events

  3. A prototype space flight intravenous injection system

    NASA Technical Reports Server (NTRS)

    Colombo, G. V.

    1985-01-01

    Medical emergencies, especially those resulting from accidents, frequently require the administration of intravenous fluids to replace lost body liquids. The development of a prototype space flight intravenous injection system is presented. The definition of requirements, injectable concentrates development, water polisher, reconstitution hardware development, administration hardware development, and prototype fabrication and testing are discussed.

  4. Partial intravenous anesthesia in cats and dogs.

    PubMed

    Duke, Tanya

    2013-03-01

    The partial intravenous anesthesia technique (PIVA) is used to lower the inspired concentration of an inhalational anesthetic by concurrent use of injectable drugs. This technique reduces the incidence of undesirable side-effects and provides superior quality of anesthesia and analgesia. Drugs commonly used for PIVA include opioids, alpha-2 adrenergic agonists, injectable anesthetic agents, and lidocaine. Most are administered by intravenous infusion.

  5. The association between symbolic and nonsymbolic numerical magnitude processing and mental versus algorithmic subtraction in adults.

    PubMed

    Linsen, Sarah; Torbeyns, Joke; Verschaffel, Lieven; Reynvoet, Bert; De Smedt, Bert

    2016-03-01

    There are two well-known computation methods for solving multi-digit subtraction items, namely mental and algorithmic computation. It has been contended that mental and algorithmic computation differentially rely on numerical magnitude processing, an assumption that has already been examined in children, but not yet in adults. Therefore, in this study, we examined how numerical magnitude processing was associated with mental and algorithmic computation, and whether this association with numerical magnitude processing was different for mental versus algorithmic computation. We also investigated whether the association between numerical magnitude processing and mental and algorithmic computation differed for measures of symbolic versus nonsymbolic numerical magnitude processing. Results showed that symbolic, and not nonsymbolic, numerical magnitude processing was associated with mental computation, but not with algorithmic computation. Additional analyses showed, however, that the size of this association with symbolic numerical magnitude processing was not significantly different for mental and algorithmic computation. We also tried to further clarify the association between numerical magnitude processing and complex calculation by also including relevant arithmetical subskills, i.e. arithmetic facts, needed for complex calculation that are also known to be dependent on numerical magnitude processing. Results showed that the associations between symbolic numerical magnitude processing and mental and algorithmic computation were fully explained by individual differences in elementary arithmetic fact knowledge.

  6. Evaluation of image quality in carotid and cerebrovascular disease: a comparative study between subtraction and routine computed tomography angiography.

    PubMed

    Zhao, De-Li; Wan, Yong; Wang, Guo-Kun; Wang, Hai-Bo; Liang, Hong-Wei; Zhou, Hai-Ting; Gao, Li; Zhang, Jin-Ling

    2016-11-01

    Few data exist comparing the image quality and diagnostic accuracy of subtraction computed tomography (CT) angiography (SCTA) in carotid and cerebrovascular arteries with routine CT angiography (RCTA). In this study, 56 patients underwent 128-row CT angiography of these vessels with review by two radiologists using routine, nonsubtracted, and SCTA protocols. Comparisons were made using a 4-point subjective rating scale in all patients. Eighteen patients were examined with both SCTA and invasive digital subtraction angiography (DSA). The accuracy of SCTA and routine CTA reformations was assessed and compared by both patient-based and vessel-based analyses of intracranial aneurysms and intracranial and extracranial arterial stenotic lesions using DSA results as the reference standard. Diagnostic accuracy in the adjacent skull base portion of the internal carotid artery (ICA) and reading time for cerebral aneurysms and vessel stenoses were obviously improved with SCTA protocol, but the accuracy in vertebro-basilar arteries was no different. The diagnostic accuracy in general was slightly increased compared with routine CTA. Review of SCTA images is an effective means to remove bone close to vessels as seen on routine CTA and has good image quality and diagnostic accuracy. SCTA is superior to routine CTA in the visualization and diagnostic accuracy of adjacent skull base part of the ICA and decreases reading time for carotid and cerebrovascular arterial imaging. © 2016, Wiley Periodicals, Inc.

  7. A posteriori registration and subtraction of periapical radiographs for the evaluation of external apical root resorption after orthodontic treatment

    PubMed Central

    Chibinski, Ana Cláudia; Coelho, Ulisses; Wambier, Letícia Stadler; Zedebski, Rosário de Arruda Moura; de Moraes, Mari Eli Leonelli; de Moraes, Luiz Cesar

    2016-01-01

    Purpose This study employed a posteriori registration and subtraction of radiographic images to quantify the apical root resorption in maxillary permanent central incisors after orthodontic treatment, and assessed whether the external apical root resorption (EARR) was related to a range of parameters involved in the treatment. Materials and Methods A sample of 79 patients (mean age, 13.5±2.2 years) with no history of trauma or endodontic treatment of the maxillary permanent central incisors was selected. Periapical radiographs taken before and after orthodontic treatment were digitized and imported to the Regeemy software. Based on an analysis of the posttreatment radiographs, the length of the incisors was measured using Image J software. The mean EARR was described in pixels and relative root resorption (%). The patient's age and gender, tooth extraction, use of elastics, and treatment duration were evaluated to identify possible correlations with EARR. Results The mean EARR observed was 15.44±12.1 pixels (5.1% resorption). No differences in the mean EARR were observed according to patient characteristics (gender, age) or treatment parameters (use of elastics, treatment duration). The only parameter that influenced the mean EARR of a patient was the need for tooth extraction. Conclusion A posteriori registration and subtraction of periapical radiographs was a suitable method to quantify EARR after orthodontic treatment, and the need for tooth extraction increased the extent of root resorption after orthodontic treatment. PMID:27051635

  8. Cadmium Subtraction Method for the Active Albedo Neutron Interrogation of Uranium

    SciTech Connect

    Worrall, Louise G.; Croft, Stephen

    2015-02-01

    This report describes work performed under the Next Generation Safeguards Initiative (NGSI) Cadmium Subtraction Project. The project objective was to explore the difference between the traditional cadmium (Cd) ratio signature and a proposed alternative Cd subtraction (or Cd difference) approach. The thinking behind the project was that a Cd subtraction method would provide a more direct measure of multiplication than the existing Cd ratio method. At the same time, it would be relatively insensitive to changes in neutron detection efficiency when properly calibrated. This is the first published experimental comparison and evaluation of the Cd ratio and Cd subtraction methods.

  9. Use and abuse of intravenous solutions.

    PubMed

    Vidt, D G

    1975-05-05

    Recent microbial infusion disasters underline the fact that infusions carry a substantial risk of morbidity and mortality. Those who make a habit of setting up an intravenous infusion as a convenient route for the administration of drugs, or just in case it may be needed later, would do well to review their methodsmthe increased probability of contamination and subsequent patient infection by the practice of adding drugs to intravenous fluids is not generally recognized. To reduce the possibility of microbial contamination, the open system with tube containers should be opened only in an aseptic environment, eg, a laminar flow hood, to allow the vacuum to be replace by aseptic air; the open-system containers should be opened only in an aseptic environment, and a bacterial filter should be inserted in the air entry port of the closure. Routine monitoring of intravenous solutions for microbial contamination should be standard procedure for any institution providing intravenous fluid therapy to patientsmthe following recommendations are suggested for consideration by hospital pharmacy and therapeutics committees: 1, The addition of drugs to intravenous fluids should be discouraged except in recognized cases of emergency. 2 when the addition of drugs to intravenous fluids is indicated, only one drug should be added to an intravenous fluid, and the only intravenous fluids used for this purpose should be isotonic saline or 5% dextrose solution in water. More complicated electrolyte solutions and protein hydrolysate solutions should never be used for additive purposes. Guidelines should be established in hospitals for the addition of drugs to intravenous fluids. These guidelines should be followed by trained personnel who have access to all available compatibility data. Additions should be made under aseptic conditions by trained personnel, preferably in the hospital pharmacy. 4. All additions of drugs should be included in the patient's permanent drug file, and the

  10. Real-time image subtraction using phase reversal technique

    NASA Astrophysics Data System (ADS)

    Venkateswara Rao, Vuyyuru; Krishna Mohan, Nandigana K.

    1999-10-01

    A simple coherent interferometric processing method for image subtraction in real-time is presented. The proposed method is based on interferometric principle using Mach- Zehnder interferometer. The phase reversal is accomplished by varying the pressure within an air-filled quartz cell inserted in one of the arms of the interferometer. Initially, the interferometer is aligned to obtain broad interference fringes in the cell region. Then the input imageries are introduced in both the arms of the interferometer and adjusted for exact registration as seen in the plane of observation. By introducing a phase change of (pi) -rad between the two arms of the interferometer, the difference between the inputs is detected in real-time on the monitor. Phase shift calibration and information processing of the proposed method is presented with the results.

  11. An Improved Spectral Background Subtraction Method Based on Wavelet Energy.

    PubMed

    Zhao, Fengkui; Wang, Jian; Wang, Aimin

    2016-12-01

    Most spectral background subtraction methods rely on the difference in frequency response of background compared with characteristic peaks. It is difficult to extract accurately the background components from the spectrum when characteristic peaks and background have overlaps in frequency domain. An improved background estimation algorithm based on iterative wavelet transform (IWT) is presented. The wavelet entropy principle is used to select the best wavelet basis. A criterion based on wavelet energy theory to determine the optimal iteration times is proposed. The case of energy dispersive X-ray spectroscopy is discussed for illustration. A simulated spectrum with a prior known background and an experimental spectrum are tested. The processing results of the simulated spectrum is compared with non-IWT and it demonstrates the superiority of the IWT. It has great significance to improve the accuracy for spectral analysis.

  12. Entanglement of coherent superposition of photon-subtraction squeezed vacuum

    NASA Astrophysics Data System (ADS)

    Liu, Cun-Jin; Ye, Wei; Zhou, Wei-Dong; Zhang, Hao-Liang; Huang, Jie-Hui; Hu, Li-Yun

    2017-10-01

    A new kind of non-Gaussian quantum state is introduced by applying nonlocal coherent superposition ( τa + sb) m of photon subtraction to two single-mode squeezed vacuum states, and the properties of entanglement are investigated according to the degree of entanglement and the average fidelity of quantum teleportation. The state can be seen as a single-variable Hermitian polynomial excited squeezed vacuum state, and its normalization factor is related to the Legendre polynomial. It is shown that, for τ = s, the maximum fidelity can be achieved, even over the classical limit (1/2), only for even-order operation m and equivalent squeezing parameters in a certain region. However, the maximum entanglement can be achieved for squeezing parameters with a π phase difference. These indicate that the optimal realizations of fidelity and entanglement could be different from one another. In addition, the parameter τ/ s has an obvious effect on entanglement and fidelity.

  13. Background Subtraction Based on Color and Depth Using Active Sensors

    PubMed Central

    Fernandez-Sanchez, Enrique J.; Diaz, Javier; Ros, Eduardo

    2013-01-01

    Depth information has been used in computer vision for a wide variety of tasks. Since active range sensors are currently available at low cost, high-quality depth maps can be used as relevant input for many applications. Background subtraction and video segmentation algorithms can be improved by fusing depth and color inputs, which are complementary and allow one to solve many classic color segmentation issues. In this paper, we describe one fusion method to combine color and depth based on an advanced color-based algorithm. This technique has been evaluated by means of a complete dataset recorded with Microsoft Kinect, which enables comparison with the original method. The proposed method outperforms the others in almost every test, showing more robustness to illumination changes, shadows, reflections and camouflage. PMID:23857259

  14. Background subtraction approach based on independent component analysis.

    PubMed

    Jiménez-Hernández, Hugo

    2010-01-01

    In this work, a new approach to background subtraction based on independent component analysis is presented. This approach assumes that background and foreground information are mixed in a given sequence of images. Then, foreground and background components are identified, if their probability density functions are separable from a mixed space. Afterwards, the components estimation process consists in calculating an unmixed matrix. The estimation of an unmixed matrix is based on a fast ICA algorithm, which is estimated as a Newton-Raphson maximization approach. Next, the motion components are represented by the mid-significant eigenvalues from the unmixed matrix. Finally, the results show the approach capabilities to detect efficiently motion in outdoors and indoors scenarios. The results show that the approach is robust to luminance conditions changes at scene.

  15. Suppression Subtractive Hybridization (SSH) and its modifications in microbiological research.

    PubMed

    Huang, Xiaowei; Li, Yunxia; Niu, Qiuhong; Zhang, Keqin

    2007-09-01

    Suppression subtractive hybridization (SSH) is an effective approach to identify the genes that vary in expression levels during different biological processes. It is often used in higher eukaryotes to study the molecular regulation in complex pathogenic progress, such as tumorigenesis and other chronic multigene-associated diseases. Because microbes have relatively smaller genomes compared with eukaryotes, aside from the analysis at the mRNA level, SSH as well as its modifications have been further employed to isolate specific chromosomal locus, study genomic diversity related with exceptional bacterial secondary metabolisms or genes with special microbial function. This review introduces the SSH and its associated methods and focus on their applications to detect specific functional genes or DNA markers in microorganisms.

  16. Ultrathin Nanostructured Metals for Highly Transmissive Plasmonic Subtractive Color Filters

    NASA Astrophysics Data System (ADS)

    Zeng, Beibei; Gao, Yongkang; Bartoli, Filbert J.

    2013-10-01

    Plasmonic color filters employing a single optically-thick nanostructured metal layer have recently generated considerable interest as an alternative to colorant-based color filtering technologies, due to their reliability, ease of fabrication, and high color tunability. However, their relatively low transmission efficiency (~30%) needs to be significantly improved for practical applications. The present work reports, for the first time, a novel plasmonic subtractive color filtering scheme that exploits the counter-intuitive phenomenon of extraordinary low transmission (ELT) through an ultrathin nanostructured metal film. This approach relies on a fundamentally different color filtering mechanism than that of existing plasmonic additive color filters, and achieves unusually high transmission efficiencies of 60 ~ 70% for simple architectures. Furthermore, owing to short-range interactions of surface plasmon polaritons at ELT resonances, our design offers high spatial resolution color filtering with compact pixel size close to the optical diffraction limit (~λ/2), creating solid applications ranging from imaging sensors to color displays.

  17. Plasma tomographic reconstruction from tangentially viewing camera with background subtraction

    SciTech Connect

    Odstrčil, M.; Mlynář, J.; Weinzettl, V.; Háček, P.; Verdoolaege, G.; Berta, M.

    2014-01-15

    Light reflections are one of the main and often underestimated issues of plasma emissivity reconstruction in visible light spectral range. Metallic and other specular components of tokamak generate systematic errors in the optical measurements that could lead to wrong interpretation of data. Our analysis is performed at data from the tokamak COMPASS. It is a D-shaped tokamak with specular metallic vessel and possibility of the H-mode plasma. Data from fast visible light camera were used for tomographic reconstruction with background reflections subtraction to study plasma boundary. In this article, we show that despite highly specular tokamak wall, it is possible to obtain a realistic reconstruction. The developed algorithm shows robust results despite of systematic errors in the optical measurements and calibration. The motivation is to obtain an independent estimate of the plasma boundary shape.

  18. Intermediate Palomar Transient Factory: Realtime Image Subtraction Pipeline

    NASA Astrophysics Data System (ADS)

    Cao, Yi; Nugent, Peter E.; Kasliwal, Mansi M.

    2016-11-01

    A fast-turnaround pipeline for realtime data reduction plays an essential role in discovering and permitting follow-up observations to young supernovae and fast-evolving transients in modern time-domain surveys. In this paper, we present the realtime image subtraction pipeline in the intermediate Palomar Transient Factory. By using high-performance computing, efficient databases, and machine-learning algorithms, this pipeline manages to reliably deliver transient candidates within 10 minutes of images being taken. Our experience in using high-performance computing resources to process big data in astronomy serves as a trailblazer to dealing with data from large-scale time-domain facilities in the near future.

  19. Single dose intravenous paracetamol or intravenous propacetamol for postoperative pain.

    PubMed

    McNicol, Ewan D; Ferguson, McKenzie C; Haroutounian, Simon; Carr, Daniel B; Schumann, Roman

    2016-05-23

    This is an updated version of the original Cochrane review published in Issue 10, 2011. Paracetamol (acetaminophen) is the most commonly prescribed analgesic for the treatment of acute pain. It may be administered orally, rectally, or intravenously. The efficacy and safety of intravenous (IV) formulations of paracetamol, IV paracetamol, and IV propacetamol (a prodrug that is metabolized to paracetamol), compared with placebo and other analgesics, is unclear. To assess the efficacy and safety of IV formulations of paracetamol for the treatment of postoperative pain in both adults and children. We ran the search for the previous review in May 2010. For this update, we searched the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 1), MEDLINE (May 2010 to 16 February 2016), EMBASE (May 2010 to 16 February 2016), LILACS (2010 to 2016), a clinical trials registry, and reference lists of reviews for randomized controlled trials (RCTs) in any language and we retrieved articles. Randomized, double-blind, placebo- or active-controlled single dose clinical trials of IV paracetamol or IV propacetamol for acute postoperative pain in adults or children. Two review authors independently extracted data, which included demographic variables, type of surgery, interventions, efficacy, and adverse events. We contacted study authors for additional information. We graded each included study for methodological quality by assessing risk of bias and employed the GRADE approach to assess the overall quality of the evidence. We included 75 studies (36 from the original review and 39 from our updated review) enrolling a total of 7200 participants.Among primary outcomes, 36% of participants receiving IV paracetamol/propacetamol experienced at least 50% pain relief over four hours compared with 16% of those receiving placebo (number needed to treat to benefit (NNT) = 5; 95% confidence interval (CI) 3.7 to 5.6, high quality evidence). The proportion of participants in IV

  20. Optical detection of intravenous infiltration

    NASA Astrophysics Data System (ADS)

    Winchester, Leonard W.; Chou, Nee-Yin

    2006-02-01

    Infiltration of medications during infusion therapy results in complications ranging from erythema and pain to tissue necrosis requiring amputation. Infiltration occurs from improper insertion of the cannula, separation of the cannula from the vein, penetration of the vein by the cannula during movement, and response of the vein to the medication. At present, visual inspection by the clinical staff is the primary means for detecting intravenous (IV) infiltration. An optical sensor was developed to monitor the needle insertion site for signs of IV infiltration. Initial studies on simulated and induced infiltrations on a swine model validated the feasibility of the methodology. The presence of IV infiltration was confirmed by visual inspection of the infusion site and/or absence of blood return in the IV line. Potential sources of error due to illumination changes, motion artifacts, and edema were also investigated. A comparison of the performance of the optical device and blinded expert observers showed that the optical sensor has higher sensitivity and specificity, and shorter detection time than the expert observers. An improved model of the infiltration monitoring device was developed and evaluated in a clinical study on induced infiltrations of healthy adult volunteers. The performance of the device was compared with the observation of a blinded expert observer. The results show that the rates of detection of infiltrations are 98% and 82% for the optical sensor and the observer, respectively. The sensitivity and specificity of the optical sensor are 0.97 and 0.98, respectively.

  1. Disposition of intravenous radioactive acyclovir

    SciTech Connect

    de Miranda, P.; Good, S.S.; Laskin, O.L.; Krasny, H.C.; Connor, J.D.; Lietman, P.S.

    1981-11-01

    The kinetic and metabolic disposition of (8-14C)acyclovir (ACV) was investigated in five subjects with advanced malignancy. The drug was administered by 1-hr intravenous infusion at doses of 0.5 and 2.5 mg/kg. Plasma and blood radioactivity-time, and plasma concentration-time data were defined by a two-compartment open kinetic model. There was nearly equivalent distribution of radioactivity in blood and plasma. The overall mean plasma half-life and total body clearance +/- SD of ACV were 2.1 +/- 0.5 hr and 297 +/- 53 ml/min/1.73 m2. Binding of ACV to plasma proteins was 15.4 +/- 4.4%. Most of the radioactive dose excreted was recovered in the urine (71% to 99%) with less than 2% excretion in the feces and only trace amounts in the expired Co2. Analyses by reverse-phase high-performance liquid chromatography indicated that 9-(carboxymethoxymethyl)guanine was the only significant urinary metabolite of ACV, accounting for 8.5% to 14.1% of the dose. A minor metabolite (less than 0.2% of dose) had the retention time of 8-hydroxy-9-((2-hydroxyethoxy)methyl)guanine. Unchanged urinary ACV ranged from 62% to 91% of the dose. There was no indication of ACV cleavage to guanine. Renal clearance of ACV was approximately three times the corresponding creatinine clearances.

  2. [Intravenous catheters and nosocomial infection].

    PubMed

    Reingardiene, Dagmara

    2004-01-01

    Peripheral, especially central venous catheters, are used with increasing frequency in the intensive care unit and in general medical wards to administer intravenous fluids and blood products, drugs, parenteral nutrition, and to monitor hemodynamic status. Catheter infection is associated with increased morbidity, mortality, and duration of hospital stay. Risk factors in the development of catheter colonization and bloodstream infections include patient factors (increased risk associated with malignancy, neutropenia, and shock) and treatment-related factors (increased risk associated with total parenteral nutrition, intensive care unit admission for any reason, and endotracheal intubation). In this review article terms and definitions of catheter-related infections, pathophysiology and epidemiology of "catheter sepsis", factors determining risk of infection, catheter types and materials, insertion procedure, choice of insertion site, indwelling time, dressing and care of the insertion site, various preventive strategies and future developments, special situations and procedures, and treatment are discussed. Reducing catheter infections rates requires a multiple-strategy approach. Therefore, intensive care units and other locations where catheters are used should implement strict guidelines and protocols for catheter insertion, care, and maintenance.

  3. Digital imaging.

    PubMed

    Daniel, Gregory B

    2009-07-01

    Medical imaging is rapidly moving toward a digital-based image system. An understanding of the principles of digital imaging is necessary to evaluate features of imaging systems and can play an important role in purchasing decisions.

  4. Putting Essential Understanding of Addition and Subtraction into Practice: Pre-K-2

    ERIC Educational Resources Information Center

    Caldwell, Janet H.; Kobett, Beth; Karp, Karen

    2014-01-01

    Do your students have the incorrect idea that addition "makes numbers bigger" and subtraction "makes numbers smaller"? Do they believe that subtraction is always "taking away"? What tasks can you offer--what questions can you ask--to determine what your students know or don't know--and move them forward in their…

  5. Toddler Subtraction with Large Sets: Further Evidence for an Analog-Magnitude Representation of Number

    ERIC Educational Resources Information Center

    Slaughter, Virginia; Kamppi, Dorian; Paynter, Jessica

    2006-01-01

    Two experiments were conducted to test the hypothesis that toddlers have access to an analog-magnitude number representation that supports numerical reasoning about relatively large numbers. Three-year-olds were presented with subtraction problems in which initial set size and proportions subtracted were systematically varied. Two sets of cookies…

  6. Model Evaluation and Multiple Strategies in Cognitive Diagnosis: An Analysis of Fraction Subtraction Data

    ERIC Educational Resources Information Center

    de la Torre, Jimmy; Douglas, Jeffrey A.

    2008-01-01

    This paper studies three models for cognitive diagnosis, each illustrated with an application to fraction subtraction data. The objective of each of these models is to classify examinees according to their mastery of skills assumed to be required for fraction subtraction. We consider the DINA model, the NIDA model, and a new model that extends the…

  7. Putting Essential Understanding of Addition and Subtraction into Practice: Pre-K-2

    ERIC Educational Resources Information Center

    Caldwell, Janet H.; Kobett, Beth; Karp, Karen

    2014-01-01

    Do your students have the incorrect idea that addition "makes numbers bigger" and subtraction "makes numbers smaller"? Do they believe that subtraction is always "taking away"? What tasks can you offer--what questions can you ask--to determine what your students know or don't know--and move them forward in their…

  8. Toddler Subtraction with Large Sets: Further Evidence for an Analog-Magnitude Representation of Number

    ERIC Educational Resources Information Center

    Slaughter, Virginia; Kamppi, Dorian; Paynter, Jessica

    2006-01-01

    Two experiments were conducted to test the hypothesis that toddlers have access to an analog-magnitude number representation that supports numerical reasoning about relatively large numbers. Three-year-olds were presented with subtraction problems in which initial set size and proportions subtracted were systematically varied. Two sets of cookies…

  9. Model Evaluation and Multiple Strategies in Cognitive Diagnosis: An Analysis of Fraction Subtraction Data

    ERIC Educational Resources Information Center

    de la Torre, Jimmy; Douglas, Jeffrey A.

    2008-01-01

    This paper studies three models for cognitive diagnosis, each illustrated with an application to fraction subtraction data. The objective of each of these models is to classify examinees according to their mastery of skills assumed to be required for fraction subtraction. We consider the DINA model, the NIDA model, and a new model that extends the…

  10. Postoperative analgesia by intravenous clonidine.

    PubMed

    Bernard, J M; Hommeril, J L; Passuti, N; Pinaud, M

    1991-10-01

    Clonidine, an alpha 2 adrenoreceptor agonist, has nonopiate antinociceptive properties, which might be an alternative for postoperative analgesia free of opioid-induced side effects. To document the analgesic properties of intravenous clonidine during the postoperative period, 50 ASA physical status 1 patients, immediately after spinal fusion, were randomly assigned to two groups, blindly administered either clonidine (5 micrograms/kg infused the 1st h and then 0.3 microgram-1.kg-1.h-1 during 11 h) or a placebo. A visual analog scale graded from 0 (no pain) to 100 mm was used to assess pain before clonidine or placebo administration (T0), at the end of the loading dose (T1) and then every 2 h (T3, T5, T7, T9, and T11). Morphine (0.1 mg/kg) was administered intramuscularly after each pain measurement if the score was greater than 50 mm. No morphine was given at T0. Hemodynamics, blood gases and plasma clonidine concentrations were measured each time the pain score was measured. The pain score decreased from 42 +/- 5 to 26 +/- 3 mm (mean +/- standard error) in the clonidine group whereas it was unchanged in the placebo group despite a greater morphine requirement (dose for each patient: 3.8 +/- 1 vs. 10.8 +/- 1.2 mg). Clonidine delayed the onset of pain and the first request for morphine injection. Mean arterial pressure decreased to 74 +/- 2 mmHg in the clonidine group (-26 +/- 2 vs. -15 +/- 2% in the placebo group at T11) despite a significant increase in the cumulative fluid volume.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Artifacts in digital coincidence timing

    DOE PAGES

    Moses, W. W.; Peng, Q.

    2014-10-16

    Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into amore » time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator.All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e. the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the 'optimal' method. In conclusion, the purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization.« less

  12. Insect Wing Displacement Measurement Using Digital Holography

    SciTech Connect

    Aguayo, Daniel D.; Mendoza Santoyo, Fernando; Torre I, Manuel H. de la; Caloca Mendez, Cristian I.

    2008-04-15

    Insects in flight have been studied with optical non destructive techniques with the purpose of using meaningful results in aerodynamics. With the availability of high resolution and large dynamic range CCD sensors the so called interferometric digital holographic technique was used to measure the surface displacement of in flight insect wings, such as butterflies. The wings were illuminated with a continuous wave Verdi laser at 532 nm, and observed with a CCD Pixelfly camera that acquire images at a rate of 11.5 frames per second at a resolution of 1392x1024 pixels and 12 Bit dynamic range. At this frame rate digital holograms of the wings were captured and processed in the usual manner, namely, each individual hologram is Fourier processed in order to find the amplitude and phase corresponding to the digital hologram. The wings displacement is obtained when subtraction between two digital holograms is performed for two different wings position, a feature applied to all consecutive frames recorded. The result of subtracting is seen as a wrapped phase fringe pattern directly related to the wing displacement. The experimental data for different butterfly flying conditions and exposure times are shown as wire mesh plots in a movie of the wings displacement.

  13. Intravenous drug delivery in neonates: lessons learnt.

    PubMed

    Sherwin, Catherine M T; Medlicott, Natalie J; Reith, David M; Broadbent, Roland S

    2014-06-01

    Intravenous drug administration presents a series of challenges that relate to the pathophysiology of the neonate and intravenous infusion systems in neonates. These challenges arise from slow intravenous flow rates, small drug volume, dead space volume and limitations on the flush volume in neonates. While there is a reasonable understanding of newborn pharmacokinetics, an appreciation of the substantial delay and variability in the rate of drug delivery from the intravenous line is often lacking. This can lead to difficulties in accurately determining the pharmacokinetic and pharmacodynamic relationship of drugs in the smallest patients. The physical variables that affect the passage of drugs through neonatal lines need to be further explored in order to improve our understanding of their impact on the delivery of drugs by this route in neonates. Through careful investigation, the underlying causes of delayed drug delivery may be identified and administration protocols can then be modified to ensure predictable, appropriate drug input kinetics.

  14. Rational use of intravenous fat emulsions.

    PubMed

    Pelham, L D

    1981-02-01

    The composition, effect on blood components, relative value compared with intravenous dextrose, clinical applications as a caloric and fatty acid source, adverse reactions, limitations, and administration of intravenous fat emulsions are reviewed. Fat emulsions provide essential fatty acids and calories and are primarily used to supplement of parenteral nutrition regimens. Their use as a major source of calories remains limited because of cost. However, the trend toward aligning intravenous nutrition to that of the normal diet and the increased demand for peripherally administered parenteral nutrition have increased demand for use. The advantages and disadvantages presented may be used by clinicians to assist in establishing the role of intravenous fat therapy in nutritional support services.

  15. Reorganization for intravenous procedures in dentistry.

    PubMed

    Litchfield, N B

    1975-08-01

    The importance of reorganization for intravenous dental procedures, involving not only premises and equipment but also the dentist and his staff, is emphasised. These matters are discussed in detail with special emphasis on certain essential factors and psychologic aspects.

  16. Digital Imaging.

    ERIC Educational Resources Information Center

    Howell, Les

    1996-01-01

    Defines a digital photograph as a numerical record of light electronically measured and recorded by a computer's scanner. States that most personal computers cannot do digital photography successfully and that digital pictures can be hard to manage and present a storage problem. Finds that, once the school has the hardware/software, picture…

  17. Digital Imaging.

    ERIC Educational Resources Information Center

    Howell, Les

    1996-01-01

    Defines a digital photograph as a numerical record of light electronically measured and recorded by a computer's scanner. States that most personal computers cannot do digital photography successfully and that digital pictures can be hard to manage and present a storage problem. Finds that, once the school has the hardware/software, picture…

  18. Digital Citizenship

    ERIC Educational Resources Information Center

    Isman, Aytekin; Canan Gungoren, Ozlem

    2014-01-01

    Era in which we live is known and referred as digital age.In this age technology is rapidly changed and developed. In light of these technological advances in 21st century, schools have the responsibility of training "digital citizen" as well as a good citizen. Digital citizens must have extensive skills, knowledge, Internet and …

  19. Improvement of two-way continuous-variable quantum key distribution with virtual photon subtraction

    NASA Astrophysics Data System (ADS)

    Zhao, Yijia; Zhang, Yichen; Li, Zhengyu; Yu, Song; Guo, Hong

    2017-08-01

    We propose a method to improve the performance of two-way continuous-variable quantum key distribution protocol by virtual photon subtraction. The virtual photon subtraction implemented via non-Gaussian post-selection not only enhances the entanglement of two-mode squeezed vacuum state but also has advantages in simplifying physical operation and promoting efficiency. In two-way protocol, virtual photon subtraction could be applied on two sources independently. Numerical simulations show that the optimal performance of renovated two-way protocol is obtained with photon subtraction only used by Alice. The transmission distance and tolerable excess noise are improved by using the virtual photon subtraction with appropriate parameters. Moreover, the tolerable excess noise maintains a high value with the increase in distance so that the robustness of two-way continuous-variable quantum key distribution system is significantly improved, especially at long transmission distance.

  20. Intravenous iron-containing products: EMA procrastination.

    PubMed

    2014-07-01

    A European reassessment has led to identical changes in the summaries of product characteristics (SPCs) for all intravenous iron-containing products: the risk of serious adverse effects is now highlighted, underlining the fact that intravenous iron-containing products should only be used when the benefits clearly outweigh the harms. Unfortunately, iron dextran still remains on the market despite a higher risk of hypersensitivity reactions than with iron sucrose.

  1. Partial intravenous anesthesia in cats and dogs

    PubMed Central

    Duke, Tanya

    2013-01-01

    The partial intravenous anesthesia technique (PIVA) is used to lower the inspired concentration of an inhalational anesthetic by concurrent use of injectable drugs. This technique reduces the incidence of undesirable side-effects and provides superior quality of anesthesia and analgesia. Drugs commonly used for PIVA include opioids, alpha-2 adrenergic agonists, injectable anesthetic agents, and lidocaine. Most are administered by intravenous infusion. PMID:23997266

  2. Contrast-Enhanced Digital Mammography and Angiogenesis

    SciTech Connect

    Rosado-Mendez, I.; Palma, B. A.; Villasenor, Y.; Benitez-Bribiesca, L.; Brandan, M. E.

    2007-11-26

    Angiogenesis could be a means for pouring contrast media around tumors. In this work, optimization of radiological parameters for contrast-enhanced subtraction techniques in mammography has been performed. A modification of Lemacks' analytical formalism was implemented to model the X-ray absorption in the breast with contrast medium and detection by a digital image receptor. Preliminary results of signal-to-noise ratio analysis show the advantage of subtracting two images taken at different energies, one prior and one posterior to the injection of contrast medium. Preliminary experimental results using a custom-made phantom have shown good agreement with calculations. A proposal is presented for the clinical application of the optimized technique, which aims at finding correlations between angiogenesis indicators and dynamic variables of contrast medium uptake.

  3. Digital Natives or Digital Tribes?

    ERIC Educational Resources Information Center

    Watson, Ian Robert

    2013-01-01

    This research builds upon the discourse surrounding digital natives. A literature review into the digital native phenomena was undertaken and found that researchers are beginning to identify the digital native as not one cohesive group but of individuals influenced by other factors. Primary research by means of questionnaire survey of technologies…

  4. Subtractive fuzzy classifier based driver distraction levels classification using EEG.

    PubMed

    Wali, Mousa Kadhim; Murugappan, Murugappan; Ahmad, Badlishah

    2013-09-01

    [Purpose] In earlier studies of driver distraction, researchers classified distraction into two levels (not distracted, and distracted). This study classified four levels of distraction (neutral, low, medium, high). [Subjects and Methods] Fifty Asian subjects (n=50, 43 males, 7 females), age range 20-35 years, who were free from any disease, participated in this study. Wireless EEG signals were recorded by 14 electrodes during four types of distraction stimuli (Global Position Systems (GPS), music player, short message service (SMS), and mental tasks). We derived the amplitude spectrum of three different frequency bands, theta, alpha, and beta of EEG. Then, based on fusion of discrete wavelet packet transforms and fast fourier transform yield, we extracted two features (power spectral density, spectral centroid frequency) of different wavelets (db4, db8, sym8, and coif5). Mean ± SD was calculated and analysis of variance (ANOVA) was performed. A fuzzy inference system classifier was applied to different wavelets using the two extracted features. [Results] The results indicate that the two features of sym8 posses highly significant discrimination across the four levels of distraction, and the best average accuracy achieved by the subtractive fuzzy classifier was 79.21% using the power spectral density feature extracted using the sym8 wavelet. [Conclusion] These findings suggest that EEG signals can be used to monitor distraction level intensity in order to alert drivers to high levels of distraction.

  5. Dual energy subtraction method for breast calcification imaging

    NASA Astrophysics Data System (ADS)

    Koukou, Vaia; Martini, Niki; Fountos, George; Michail, Christos; Sotiropoulou, Panagiota; Bakas, Athanasios; Kalyvas, Nektarios; Kandarakis, Ioannis; Speller, Robert; Nikiforidis, George

    2017-03-01

    The aim of this work was to present an experimental dual energy (DE) method for the visualization of microcalcifications (μCs). A modified radiographic X-ray tube combined with a high resolution complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) X-ray detector was used. A 40/70 kV spectral combination was filtered with 100 μm cadmium (Cd) and 1000 μm copper (Cu) for the low/high-energy combination. Homogenous and inhomogeneous breast phantoms and two calcification phantoms were constructed with various calcification thicknesses, ranging from 16 to 152 μm . Contrast-to-noise ratio (CNR) was calculated from the DE subtracted images for various entrance surface doses. A calcification thickness of 152 μm was visible, with mean glandular doses (MGD) in the acceptable levels (below 3 mGy). Additional post-processing on the DE images of the inhomogeneous breast phantom resulted in a minimum visible calcification thickness of 93 μm (MGD=1.62 mGy). The proposed DE method could potentially improve calcification visibility in DE breast calcification imaging.

  6. Removal of interference from fetal MEG by frequency dependent subtraction

    PubMed Central

    Vrba, J.; McCubbin, J.; Govindan, R.B.; Vairavan, S.; Murphy, P.; Preissl, H.; Lowery, C.L.; Eswaran, H.

    2011-01-01

    Fetal magnetoencephalography (fMEG) recordings are contaminated by maternal and fetal magnetocardiography (MCG) signals and by other biological and environmental interference. Currently, all methods for the attenuation of these signals are based on a time-domain approach. We have developed and tested a frequency dependent procedure for removal of MCG and other interference from the fMEG recordings. The method uses a set of reference channels and performs subtraction of interference in the frequency domain (SUBTR). The interference-free frequency domain signals are converted back to the time domain. We compare the performance of the frequency dependent approach with our present approach for MCG attenuation based on orthogonal projection (OP). SUBTR has an advantage over OP and similar template approaches because it removes not only the MCG but also other small amplitude biological interference, avoids the difficulties with inaccurate determination of the OP operator, provides more consistent and stable fMEG results, does not cause signal redistribution, and if references are selected judiciously, it does not reduce fMEG signal amplitude. SUBTR was found to perform well in simulations and on real fMEG recordings, and has a potential to improve the detection of fetal brain signals. The SUBTR removes interference without the need for a model of the individual interference sources. The method may be of interest for any sensor array noise reduction application where signal-free reference channels are available. PMID:21930216

  7. SPECKLE NOISE SUBTRACTION AND SUPPRESSION WITH ADAPTIVE OPTICS CORONAGRAPHIC IMAGING

    SciTech Connect

    Ren Deqing; Dou Jiangpei; Zhang Xi; Zhu Yongtian

    2012-07-10

    Future ground-based direct imaging of exoplanets depends critically on high-contrast coronagraph and wave-front manipulation. A coronagraph is designed to remove most of the unaberrated starlight. Because of the wave-front error, which is inherit from the atmospheric turbulence from ground observations, a coronagraph cannot deliver its theoretical performance, and speckle noise will limit the high-contrast imaging performance. Recently, extreme adaptive optics, which can deliver an extremely high Strehl ratio, is being developed for such a challenging mission. In this publication, we show that barely taking a long-exposure image does not provide much gain for coronagraphic imaging with adaptive optics. We further discuss a speckle subtraction and suppression technique that fully takes advantage of the high contrast provided by the coronagraph, as well as the wave front corrected by the adaptive optics. This technique works well for coronagraphic imaging with conventional adaptive optics with a moderate Strehl ratio, as well as for extreme adaptive optics with a high Strehl ratio. We show how to substrate and suppress speckle noise efficiently up to the third order, which is critical for future ground-based high-contrast imaging. Numerical simulations are conducted to fully demonstrate this technique.

  8. Linear model for fast background subtraction in oligonucleotide microarrays

    PubMed Central

    2009-01-01

    Background One important preprocessing step in the analysis of microarray data is background subtraction. In high-density oligonucleotide arrays this is recognized as a crucial step for the global performance of the data analysis from raw intensities to expression values. Results We propose here an algorithm for background estimation based on a model in which the cost function is quadratic in a set of fitting parameters such that minimization can be performed through linear algebra. The model incorporates two effects: 1) Correlated intensities between neighboring features in the chip and 2) sequence-dependent affinities for non-specific hybridization fitted by an extended nearest-neighbor model. Conclusion The algorithm has been tested on 360 GeneChips from publicly available data of recent expression experiments. The algorithm is fast and accurate. Strong correlations between the fitted values for different experiments as well as between the free-energy parameters and their counterparts in aqueous solution indicate that the model captures a significant part of the underlying physical chemistry. PMID:19917117

  9. Identification of formaldehyde-responsive genes by suppression subtractive hybridization.

    PubMed

    Lee, Min-Ho; Kim, Young-Ae; Na, Tae-Young; Kim, Sung-Hye; Shin, Young Kee; Lee, Byung-Hoon; Shin, Ho-Sang; Lee, Mi-Ock

    2008-01-14

    Formaldehyde is frequently used in indoor household and occupational environments. Inhalation of formaldehyde invokes an inflammatory response, including a variety of allergic signs and symptoms. Therefore, formaldehyde has been considered as the most prevalent cause of sick building syndrome, which has become a major social problem, especially in developing urban areas. Further formaldehyde is classified as a genotoxicant in the respiratory tract of rats and humans. To better understand the molecular mechanisms involved in formaldehyde intoxication, we sought differentially regulated genes by formaldehyde exposure to Hs 680.Tr human trachea cells, using polymerase chain reaction (PCR)-based suppression subtractive hybridization. We identified 27 different formaldehyde-inducible genes, including those coding for the major histocompatibility complex, class IA, calcyclin, glutathione S-transferase pi, mouse double minute 2 (MDM2), platelet-derived growth factor receptor alpha, and which are known to be associated with cell proliferation and differentiation, immunity and inflammation, and detoxification. Induction of these genes by formaldehyde treatment was confirmed by reverse transcription PCR and western blot analysis. Further, the expression of calcyclin, glutathione S-transferase pi, PDGFRA and MDM2 were significantly induced in the tracheal epithelium of Sprague Dawley rats after formaldehyde inhalation. Our results suggest that the elevated levels of these genes may be associated with the formaldehyde-induced toxicity, and that they deserve evaluation as potential biomarkers for formaldehyde intoxication.

  10. Subtractive transcriptomics : establishing polarity drives human endothelial morphogenesis

    SciTech Connect

    Glesne, D. A.; Zhang, W.; Mandava, S.; Ursos, L.; Buell, M. E.; Makowski, L.; Rodi, D. J.; Biosciences Division

    2006-04-15

    Although investigations of mature normal and tumor-derived capillaries have resulted in characterization of these structures at the phenotypic level, less is known regarding the initial molecular cues for cellular assembly of endothelial cells into human capillaries. Here, we employ a novel combination of microenvironmental manipulation and microarray data filtration over narrowly delineated temporal data series to identify the morphogenesis component apart from the proliferation component, as pooled human microvascular-derived endothelial cells are induced to form capillary-like structures in vitro in a murine tumor-derived matrix. The 217 morphogenesis-specific genes identified using this subtractive transcriptomics approach are mostly independent of the angiogenic proteins currently used as therapeutic targets for aberrant angiogenesis. Quantitative real-time PCR was used to validate 20% of these transcripts. Immunofluorescent analysis of proliferating and tube-forming cells validates at the protein level the morphogenesis-specific expression pattern of 16 of the 217 gene products identified. The transcripts that are selectively up-regulated in tube-forming endothelial cells reveal a temporal expression pattern of genes primarily associated with intracellular trafficking, guided migration, cytoskeletal reorganization, cellular adhesion, and proliferation inhibition. These data show that a sequential upregulation of genes that establish and maintain polarity occurs during migration and morphogenesis of in vitro human endothelial cells undergoing tubulogenesis; some of which may well be effective as novel antiangiogenic drug targets.

  11. Multiplicative and subtractive focal volume engineering in coherent Raman microscopy

    PubMed Central

    Raghunathan, Varun; Potma, Eric Olaf

    2012-01-01

    Rigorous calculations are performed to study the effective reduction of the nonlinear excitation volumes when using phase-only masks to condition the pump and Stokes driving fields. Focal volume reduction was achieved using both a multiplicative operation of the excitation fields as well as a subtractive operation. Using a tunable optical bottle beam for the Stokes field, an effective reduction of the width of the excitation volume by a factor of 1.5 can be achieved in the focal plane. Further reduction of the focal volume introduces a rapid growth of sidelobes, which renders such volumes unsuitable for imaging applications. In addition, phase sensitive detection was found to provide information from selective sub-divisions of the engineered coherent anti-Stokes Raman scattering excitation volume. In the case of isolated nanoparticles, an apparent resolution improvement by a factor of 3 is demonstrated, and it is shown that the size of sub-diffraction-limited particles can be accurately determined using phase sensitive detection. PMID:21045900

  12. Microwave detection of breast tumors: comparison of skin subtraction algorithms

    NASA Astrophysics Data System (ADS)

    Fear, Elise C.; Stuchly, Maria A.

    2000-07-01

    Early detection of breast cancer is an important part of effective treatment. Microwave detection of breast cancer is of interest due to the contrast in dielectric properties of normal and malignant breast tissues. We are investigating a confocal microwave imaging system that adapts ideas from ground penetrating radar to breast cancer detection. In the proposed system, the patient lies prone with the breast extending through a hole in the examining table and encircled by an array of antennas. The breast is illuminated sequentially by each antenna with an ultrawideband signal, and the returns are recorded at the same antenna. Because the antennas are offset from the breast, the dominant component of the recorded returns is the reflection from the thin layer of breast skin. Two methods of reducing this reflection are compared, namely approximation of the signal with two time shifted, scaled and summed returns from a cylinder of skin, and subtraction of the mean of the set of aligned returns. Both approaches provide effective decrease of the skin signal, allowing for tumor detection.

  13. Intravenous fluids in acute decompensated heart failure.

    PubMed

    Bikdeli, Behnood; Strait, Kelly M; Dharmarajan, Kumar; Li, Shu-Xia; Mody, Purav; Partovian, Chohreh; Coca, Steven G; Kim, Nancy; Horwitz, Leora I; Testani, Jeffrey M; Krumholz, Harlan M

    2015-02-01

    This study sought to determine the use of intravenous fluids in the early care of patients with acute decompensated heart failure (HF) who are treated with loop diuretics. Intravenous fluids are routinely provided to many hospitalized patients. We conducted a retrospective cohort study of patients admitted with HF to 346 hospitals from 2009 to 2010. We assessed the use of intravenous fluids during the first 2 days of hospitalization. We determined the frequency of adverse in-hospital outcomes. We assessed variation in the use of intravenous fluids across hospitals and patient groups. Among 131,430 hospitalizations for HF, 13,806 (11%) were in patients treated with intravenous fluids during the first 2 days. The median volume of administered fluid was 1,000 ml (interquartile range: 1,000 to 2,000 ml), and the most commonly used fluids were normal saline (80%) and half-normal saline (12%). Demographic characteristics and comorbidities were similar in hospitalizations in which patients did and did not receive fluids. Patients who were treated with intravenous fluids had higher rates of subsequent critical care admission (5.7% vs. 3.8%; p < 0.0001), intubation (1.4% vs. 1.0%; p = 0.0012), renal replacement therapy (0.6% vs. 0.3%; p < 0.0001), and hospital death (3.3% vs. 1.8%; p < 0.0001) compared with those who received only diuretics. The proportion of hospitalizations that used fluid treatment varied widely across hospitals (range: 0% to 71%; median: 12.5%). Many patients who are hospitalized with HF and receive diuretics also receive intravenous fluids during their early inpatient care, and the proportion varies among hospitals. Such practice is associated with worse outcomes and warrants further investigation. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  14. The functional architectures of addition and subtraction: Network discovery using fMRI and DCM.

    PubMed

    Yang, Yang; Zhong, Ning; Friston, Karl; Imamura, Kazuyuki; Lu, Shengfu; Li, Mi; Zhou, Haiyan; Wang, Haiyuan; Li, Kuncheng; Hu, Bin

    2017-03-27

    The neuronal mechanisms underlying arithmetic calculations are not well understood but the differences between mental addition and subtraction could be particularly revealing. Using fMRI and dynamic causal modeling (DCM), this study aimed to identify the distinct neuronal architectures engaged by the cognitive processes of simple addition and subtraction. Our results revealed significantly greater activation during subtraction in regions along the dorsal pathway, including the left inferior frontal gyrus (IFG), middle portion of dorsolateral prefrontal cortex (mDLPFC), and supplementary motor area (SMA), compared with addition. Subsequent analysis of the underlying changes in connectivity - with DCM - revealed a common circuit processing basic (numeric) attributes and the retrieval of arithmetic facts. However, DCM showed that addition was more likely to engage (numeric) retrieval-based circuits in the left hemisphere, while subtraction tended to draw on (magnitude) processing in bilateral parietal cortex, especially the right intraparietal sulcus (IPS). Our findings endorse previous hypotheses about the differences in strategic implementation, dominant hemisphere, and the neuronal circuits underlying addition and subtraction. Moreover, for simple arithmetic, our connectivity results suggest that subtraction calls on more complex processing than addition: auxiliary phonological, visual, and motor processes, for representing numbers, were engaged by subtraction, relative to addition. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

  15. A Wireless FSCV Monitoring IC with Analog Background Subtraction and UWB Telemetry

    PubMed Central

    Dorta-Quiñones, Carlos I.; Wang, Xiao Y.; Dokania, Rajeev K.; Gailey, Alycia; Lindau, Manfred; Apsel, Alyssa B.

    2015-01-01

    A 30-μW wireless fast-scan cyclic voltammetry monitoring integrated circuit for ultra-wideband (UWB) transmission of dopamine release events in freely-behaving small animals is presented. On-chip integration of analog background subtraction and UWB telemetry yields a 32-fold increase in resolution versus standard Nyquist-rate conversion alone, near a four-fold decrease in the volume of uplink data versus single-bit, third-order, delta-sigma modulation, and more than a 20-fold reduction in transmit power versus narrowband transmission for low data rates. The 1.5-mm2 chip, which was fabricated in 65-nm CMOS technology, consists of a low-noise potentiostat frontend, a two-step analog-to-digital converter (ADC), and an impulse-radio UWB transmitter (TX). The duty-cycled frontend and ADC/UWB-TX blocks draw 4 μA and 15 μA from 3-V and 1.2-V supplies, respectively. The chip achieves an input-referred current noise of 92 pArms and an input current range of ±430 nA at a conversion rate of 10 kHz. The packaged device operates from a 3-V coin-cell battery, measures 4.7 × 1.9 cm2, weighs 4.3 g (including the battery and antenna), and can be carried by small animals. The system was validated by wirelessly recording flow-injection of dopamine with concentrations in the range of 250 nM to 1 μM with a carbon-fiber microelectrode (CFM) using 300-V/s FSCV. PMID:26057983

  16. A Wireless FSCV Monitoring IC With Analog Background Subtraction and UWB Telemetry.

    PubMed

    Dorta-Quiñones, Carlos I; Wang, Xiao Y; Dokania, Rajeev K; Gailey, Alycia; Lindau, Manfred; Apsel, Alyssa B

    2016-04-01

    A 30-μW wireless fast-scan cyclic voltammetry monitoring integrated circuit for ultra-wideband (UWB) transmission of dopamine release events in freely-behaving small animals is presented. On-chip integration of analog background subtraction and UWB telemetry yields a 32-fold increase in resolution versus standard Nyquist-rate conversion alone, near a four-fold decrease in the volume of uplink data versus single-bit, third-order, delta-sigma modulation, and more than a 20-fold reduction in transmit power versus narrowband transmission for low data rates. The 1.5- mm(2) chip, which was fabricated in 65-nm CMOS technology, consists of a low-noise potentiostat frontend, a two-step analog-to-digital converter (ADC), and an impulse-radio UWB transmitter (TX). The duty-cycled frontend and ADC/UWB-TX blocks draw 4 μA and 15 μA from 3-V and 1.2-V supplies, respectively. The chip achieves an input-referred current noise of 92 pA(rms) and an input current range of ±430 nA at a conversion rate of 10 kHz. The packaged device operates from a 3-V coin-cell battery, measures 4.7 × 1.9 cm(2), weighs 4.3 g (including the battery and antenna), and can be carried by small animals. The system was validated by wirelessly recording flow-injection of dopamine with concentrations in the range of 250 nM to 1 μM with a carbon-fiber microelectrode (CFM) using 300-V/s FSCV.

  17. Algorithms for intravenous insulin delivery.

    PubMed

    Braithwaite, Susan S; Clement, Stephen

    2008-08-01

    This review aims to classify algorithms for intravenous insulin infusion according to design. Essential input data include the current blood glucose (BG(current)), the previous blood glucose (BG(previous)), the test time of BG(current) (test time(current)), the test time of BG(previous) (test time(previous)), and the previous insulin infusion rate (IR(previous)). Output data consist of the next insulin infusion rate (IR(next)) and next test time. The classification differentiates between "IR" and "MR" algorithm types, both defined as a rule for assigning an insulin infusion rate (IR), having a glycemic target. Both types are capable of assigning the IR for the next iteration of the algorithm (IR(next)) as an increasing function of BG(current), IR(previous), and rate-of-change of BG with respect to time, each treated as an independent variable. Algorithms of the IR type directly seek to define IR(next) as an incremental adjustment to IR(previous). At test time(current), under an IR algorithm the differences in values of IR(next) that might be assigned depending upon the value of BG(current) are not necessarily continuously dependent upon, proportionate to, or commensurate with either the IR(previous) or the rate-of-change of BG. Algorithms of the MR type create a family of IR functions of BG differing according to maintenance rate (MR), each being an iso-MR curve. The change of IR(next) with respect to BG(current) is a strictly increasing function of MR. At test time(current), algorithms of the MR type use IR(previous) and the rate-of-change of BG to define the MR, multiplier, or column assignment, which will be used for patient assignment to the right iso-MR curve and as precedent for IR(next). Bolus insulin therapy is especially effective when used in proportion to carbohydrate load to cover anticipated incremental transitory enteral or parenteral carbohydrate exposure. Specific distinguishing algorithm design features and choice of parameters may be important to

  18. Ending up with Less: The Role of Working Memory in Solving Simple Subtraction Problems with Positive and Negative Answers

    ERIC Educational Resources Information Center

    Robert, Nicole D.; LeFevre, Jo-Anne

    2013-01-01

    Does solving subtraction problems with negative answers (e.g., 5-14) require different cognitive processes than solving problems with positive answers (e.g., 14-5)? In a dual-task experiment, young adults (N=39) combined subtraction with two working memory tasks, verbal memory and visual-spatial memory. All of the subtraction problems required…

  19. Subtractive Plasma-Assisted-Etch Process for Developing High Performance Nanocrystalline Zinc-Oxide Thin-Film-Transistors

    DTIC Science & Technology

    2015-03-26

    SUBTRACTIVE PLASMA -ASSISTED- ETCH PROCESS FOR DEVELOPING HIGH PERFORMANCE NANOCRYSTALLINE ZINC-OXIDE...Government and is not subject to copyright protection in the United States. AFIT-ENG-MS-15-M-027 SUBTRACTIVE PLASMA -ASSISTED- ETCH PROCESS FOR...15-M-027 SUBTRACTIVE PLASMA -ASSISTED- ETCH PROCESS FOR DEVELOPING HIGH PERFORMANCE NANOCRYSTALLINE ZINC-OXIDE THIN-FILM-TRANSISTORS Thomas

  20. Redefining the Whole: Common Errors in Elementary Preservice Teachers' Self-Authored Word Problems for Fraction Subtraction

    ERIC Educational Resources Information Center

    Dixon, Juli K.; Andreasen, Janet B.; Avila, Cheryl L.; Bawatneh, Zyad; Deichert, Deana L.; Howse, Tashana D.; Turner, Mercedes Sotillo

    2014-01-01

    A goal of this study was to examine elementary preservice teachers' (PSTs) ability to contextualize and decontextualize fraction subtraction by asking them to write word problems to represent fraction subtraction expressions and to choose prewritten word problems to support given fraction subtraction expressions. Three themes emerged from the…

  1. Ending up with Less: The Role of Working Memory in Solving Simple Subtraction Problems with Positive and Negative Answers

    ERIC Educational Resources Information Center

    Robert, Nicole D.; LeFevre, Jo-Anne

    2013-01-01

    Does solving subtraction problems with negative answers (e.g., 5-14) require different cognitive processes than solving problems with positive answers (e.g., 14-5)? In a dual-task experiment, young adults (N=39) combined subtraction with two working memory tasks, verbal memory and visual-spatial memory. All of the subtraction problems required…

  2. Exponential renormalisation. II. Bogoliubov's R-operation and momentum subtraction schemes

    SciTech Connect

    Ebrahimi-Fard, Kurusch

    2012-08-15

    This article aims at advancing the recently introduced exponential method for renormalisation in perturbative quantum field theory. It is shown that this new procedure provides a meaningful recursive scheme in the context of the algebraic and group theoretical approach to renormalisation. In particular, we describe in detail a Hopf algebraic formulation of Bogoliubov's classical R-operation and counterterm recursion in the context of momentum subtraction schemes. This approach allows us to propose an algebraic classification of different subtraction schemes. Our results shed light on the peculiar algebraic role played by the degrees of Taylor jet expansions, especially the notion of minimal subtraction and oversubtractions.

  3. WAXS fat subtraction model to estimate differential linear scattering coefficients of fatless breast tissue: Phantom materials evaluation

    SciTech Connect

    Tang, Robert Y.; Laamanen, Curtis McDonald, Nancy; LeClair, Robert J.

    2014-05-15

    measure μ{sub s} of homogeneous samples was quantitatively accurate. Simple WAXS models predicted the probabilities for specific x-ray scattering to occur from heterogeneous biopsies. The fat subtraction model can allow μ{sub s} signals of breast cancer and fibroglandular tissue to be compared without the effects of fat provided there is an independent measurement of the fat volume fraction ν{sub f}. Future work will consist of devising a quantitative x-ray digital imaging method to estimate ν{sub f} in ex vivo breast samples.

  4. Digital Imaging

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Digital Imaging is the computer processed numerical representation of physical images. Enhancement of images results in easier interpretation. Quantitative digital image analysis by Perceptive Scientific Instruments, locates objects within an image and measures them to extract quantitative information. Applications are CAT scanners, radiography, microscopy in medicine as well as various industrial and manufacturing uses. The PSICOM 327 performs all digital image analysis functions. It is based on Jet Propulsion Laboratory technology, is accurate and cost efficient.

  5. Digital metamaterials.

    PubMed

    Della Giovampaola, Cristian; Engheta, Nader

    2014-12-01

    Balancing complexity and simplicity has played an important role in the development of many fields in science and engineering. One of the well-known and powerful examples of such balance can be found in Boolean algebra and its impact on the birth of digital electronics and the digital information age. The simplicity of using only two numbers, '0' and '1', in a binary system for describing an arbitrary quantity made the fields of digital electronics and digital signal processing powerful and ubiquitous. Here, inspired by the binary concept, we propose to develop the notion of digital metamaterials. Specifically, we investigate how one can synthesize an electromagnetic metamaterial with a desired permittivity, using as building blocks only two elemental materials, which we call 'metamaterial bits', with two distinct permittivity functions. We demonstrate, analytically and numerically, how proper spatial mixtures of such metamaterial bits lead to elemental 'metamaterial bytes' with effective material parameters that are different from the parameters of the metamaterial bits. We then apply this methodology to several design examples of optical elements, such as digital convex lenses, flat graded-index digital lenses, digital constructs for epsilon-near-zero (ENZ) supercoupling and digital hyperlenses, thus highlighting the power and simplicity of the methodology.

  6. Digital printing

    NASA Astrophysics Data System (ADS)

    Sobotka, Werner K.

    1997-02-01

    Digital printing is described as a tool to replace conventional printing machines completely. Still this goal was not reached until now with any of the digital printing technologies to be described in the paper. Productivity and costs are still the main parameters and are not really solved until now. Quality in digital printing is no problem anymore. Definition of digital printing is to transfer digital datas directly on the paper surface. This step can be carried out directly or with the use of an intermediate image carrier. Keywords in digital printing are: computer- to-press; erasable image carrier; image carrier with memory. Digital printing is also the logical development of the new digital area as it is pointed out in Nicholas Negropotes book 'Being Digital' and also the answer to networking and Internet technologies. Creating images text and color in one country and publishing the datas in another country or continent is the main advantage. Printing on demand another big advantage and last but not least personalization the last big advantage. Costs and being able to coop with this new world of prepress technology is the biggest disadvantage. Therefore the very optimistic growth rates for the next few years are really nonexistent. The development of complete new markets is too slow and the replacing of old markets is too small.

  7. A clinical audit of thallium-technetium subtraction parathyroid scans.

    PubMed Central

    Samanta, A.; Wilson, B.; Iqbal, J.; Burden, A. C.; Walls, J.; Cosgriff, P.

    1990-01-01

    Eighty six consecutive thallium-technetium subtraction parathyroid scans performed over a three year period for hypercalcaemia have been evaluated. Twelve had chronic renal failure, 11 had hypercalcaemia due to non-hyperparathyroid causes and in 10 the imaging study was technically inadequate. The remaining 53 technically adequate studies performed for hypercalcaemia clinically thought to be possibly due to hyperparathyroidism have been analysed. Of 20 (38%) positive scans, 13 came to surgery (10 correctly localized parathyroid adenomas, 2 with multiple gland hyperplasia, and 1 papillary carcinoma of the thyroid). Of 33 (62%) negative scans, 9 had surgical exploration on the basis of strong clinical grounds and all had parathyroid adenomas. Multiple biochemical parameters have been assessed in relation to a positive outcome on scan. The adjusted calcium-phosphate product and the ratio of the adjusted calcium-phosphate product to creatinine (Ca x P/Cr) were both significantly lower in the scan positive group (P less than 0.01). The scan positive group had a significantly higher mean level of PTH (P less than 0.001) and lower mean level of phosphate (P less than 0.001). The present experience shows that parathyroid imaging is useful in localizing parathyroid adenomas in 50% of cases (10 out of 19). This figure is at the lower end of the range of previously published results. It is less effective in demonstrating multiple gland hyperplasia. The decision as to whether to undertake surgical exploration when the scan is negative has been based successfully on clinical judgement. We feel that an analysis of this nature is important, as it gives insights into the practical relevance of parathyroid imaging in the context of routine clinical work. PMID:2170959

  8. Promotion of gallbladder emptying by intravenous aminoacids.

    PubMed

    Zoli, G; Ballinger, A; Healy, J; O'Donnell, L J; Clark, M; Farthing, M J

    1993-05-15

    Patients receiving total intravenous nutrition have inert gallbladders; gallbladder sludge and gallstones often develop, but are preventable if gallbladder emptying can be improved. We measured the effect of giving rapid intravenous infusions of aminoacid solutions in eight normal subjects. Four regimens were tested (250 mL over 30 min, 250 mL over 10 min, 125 mL over 5 min, and 50 mL over 5 min). Gallbladder emptying, as measured by ultrasound and cholecystokinin release, depended on both the amount and the rate of aminoacid infusion. Rapid infusion of 125 mL of an aminoacid mixture (Synthamin 14 without electrolytes) over 5 min (2.1 g per min) produced a 64% reduction in gallbladder volume within 30 min, whereas a 50 mL infusion over 5 min produced only a 22% reduction. Intermittent rapid infusion of small amounts of aminoacids may prevent gallstones in patients receiving intravenous nutrition.

  9. Intravenous immunoglobulin therapy for antibody deficiency.

    PubMed Central

    Nolte, M T; Pirofsky, B; Gerritz, G A; Golding, B

    1979-01-01

    Twenty patients with antibody deficiency were treated at random with either intramuscular immune serum globulin (ISG) or intravenous modified immune serum globulin (M-ISG). Fourteen patients received of 259 M-ISG infusions during 242 months of treatment. Catastrophic vasomotor reactions were not observed. A single dose of 150 mg/kilo M-ISG increased serum IgG values a mean 248 mg%. Intravenous M-ISG therapy was effective in reducing the incidence of acute infections. Subjects receiving M-ISG developed 0.103 acute infections per month of treatment. Patients injected with ISG had 0.295 acute infections per month of treatment. Seven subjects had separate courses of both intravenous M-ISG and intramuscular ISG. Acute infections per month of treatment for M-ISG and ISG were 0.104 and 0.406, respectively. PMID:477026

  10. Mercury excretion and intravenous ascorbic acid.

    PubMed

    Dirks, M J; Davis, D R; Cheraskin, E; Jackson, J A

    1994-01-01

    We tested the hypothesis that intravenous ascorbic acid increases urinary excretion of mercury in subjects with low mercury levels from dental amalgam, food, and other sources. From 89 adult volunteers we selected 28 subjects with the highest mercury excretions (2 to 14 micrograms/24 h). We administered intravenous infusions of 500 ml lactated Ringer's solution with and without addition of 750 mg of ascorbic acid/kg body weight, up to 60 g ascorbic acid. Average mercury excretion during the 24 h after infusion of ascorbic acid was 4.0 +/- 0.5 micrograms (mean +/- SEM), which was not significantly more than after infusion of Ringer's solution alone (3.7 +/- 0.5 micrograms). Lead excretion was similarly unaffected. If ascorbic acid administered intravenously benefits some persons with suspected adverse reactions to mercury, the benefit in subjects similar to ours appears unrelated to short-term enhanced excretion of mercury or lead.

  11. A theoretical comparison of x-ray angiographic image quality using energy-dependent and conventional subtraction methods.

    PubMed

    Tanguay, Jesse; Kim, Ho Kyung; Cunningham, Ian A

    2012-01-01

    X-ray digital subtraction angiography (DSA) is widely used for vascular imaging. However, the need to subtract a mask image can result in motion artifacts and compromised image quality. The current interest in energy-resolving photon-counting (EPC) detectors offers the promise of eliminating motion artifacts and other advanced applications using a single exposure. The authors describe a method of assessing the iodine signal-to-noise ratio (SNR) that may be achieved with energy-resolved angiography (ERA) to enable a direct comparison with other approaches including DSA and dual-energy angiography for the same patient exposure. A linearized noise-propagation approach, combined with linear expressions of dual-energy and energy-resolved imaging, is used to describe the iodine SNR. The results were validated by a Monte Carlo calculation for all three approaches and compared visually for dual-energy and DSA imaging using a simple angiographic phantom with a CsI-based flat-panel detector. The linearized SNR calculations show excellent agreement with Monte Carlo results. While dual-energy methods require an increased tube heat load of 2× to 4× compared to DSA, and photon-counting detectors are not yet ready for angiographic imaging, the available iodine SNR for both methods as tested is within 10% of that of conventional DSA for the same patient exposure over a wide range of patient thicknesses and iodine concentrations. While the energy-based methods are not necessarily optimized and further improvements are likely, the linearized noise-propagation analysis provides the theoretical framework of a level playing field for optimization studies and comparison with conventional DSA. It is concluded that both dual-energy and photon-counting approaches have the potential to provide similar angiographic image quality to DSA.

  12. Optimized intravenous Flat Detector CT for non-invasive visualization of intracranial stents: first results.

    PubMed

    Struffert, Tobias; Kloska, Stephan; Engelhorn, Tobias; Deuerling-Zheng, Yu; Ott, Sabine; Doelken, Marc; Saake, Marc; Köhrmann, Martin; Doerfler, Arnd

    2011-02-01

    As stents for treating intracranial atherosclerotic stenosis may develop in-stent re-stenosis (ISR) in up to 30%, follow-up imaging is mandatory. Residual stenosis (RS) is not rare. We evaluated an optimised Flat Detector CT protocol with intravenous contrast material application (i.v. FD-CTA) for non-invasive follow-up. In 12 patients with intracranial stents, follow-up imaging was performed using i.v. FD-CTA. MPR, subtracted MIP and VRT reconstructions were used to correlate to intra-arterial angiography (DSA). Two neuroradiologists evaluated the images in anonymous consensus reading and calculated the ISR or RS. Correlation coefficients and a Wilcoxon test were used for statistical analysis. In 4 patients, no stenosis was detected. In 6 patients RS and in two cases ISR by intima hyperplasia perfectly visible on MPR reconstructions of i.v. FD-CTA were detected. Wilcoxon's test showed no significant differences between the methods (p > 0.05). We found a high correlation with coefficients of the pairs DSA/ FD-CT MIP r = 0.91, DSA/ FD-CT MPR r = 0.82 and FD-CT MIP/ FD-CT MPR r = 0.8. Intravenous FD-CTA could clearly visualise the stent and the lumen, allowing ISR or RS to be recognised. FD-CTA provides a non-invasive depiction of intracranial stents and might replace DSA for non-invasive follow-up imaging.

  13. A pocket calculator program for intravenous requirements.

    PubMed

    Rich, A J; Wright, P D

    1980-05-01

    A program to calculate the 24-h intravenous requirements of water, nitrogen, energy and six electrolytes on a card-programmable pocket calculator is described. Comparison of calculator-generated requirements with intravenous feeding regimens prescribed by junior clinicians for 8 ill patients suggests that the clinicians provide too much water and too little nitrogen and energy. Certain program modifications are necessary to widen the useful clinical application of the calculator, but in general it is a useful bedside tool capable of further application to suitable medical tasks.

  14. Intravenous maintenance fluid therapy in children.

    PubMed

    McNab, Sarah

    2016-02-01

    Intravenous fluids are frequently used in paediatrics but have been associated with significant adverse outcomes. Understanding the composition of fluid prescribed and administering an appropriate rate is essential for safe fluid administration, along with regular monitoring. Recent evidence has shown that using an isotonic fluid with a sodium concentration similar to plasma can decrease the risk of hyponatraemia without an increase in adverse effects. This should lead to a change in guidelines: isotonic fluid should now be used as the primary maintenance intravenous fluid given to the majority of children. © 2016 The Author Journal of Paediatrics and Child Health © 2016 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

  15. Pulmonary edema induced by intravenous ethchlorvynol.

    PubMed

    Conces, D J; Kreipke, D L; Tarver, R D

    1986-11-01

    The intravenous injection of ethchlorvynol is an uncommon cause of noncardiac pulmonary edema. Two cases of intravenous ethchlorvynol-induced pulmonary edema are presented. The patients fell asleep after injecting the liquid contents of Placydil capsules (ethchlorvynol) and awoke several hours later with severe dyspnea. Arterial blood gases demonstrated marked hypoxia. Chest radiographs revealed bilateral diffuse alveolar densities. The patients' symptoms and radiographic findings resolved after several days of supportive care. Changes in the lung caused by ethchlorvynol may be the result of direct effect of the drug on the lung.

  16. Digital hum filtering

    USGS Publications Warehouse

    Knapp, R.W.; Anderson, N.L.

    1994-01-01

    Data may be overprinted by a steady-state cyclical noise (hum). Steady-state indicates that the noise is invariant with time; its attributes, frequency, amplitude, and phase, do not change with time. Hum recorded on seismic data usually is powerline noise and associated higher harmonics; leakage from full-waveform rectified cathodic protection devices that contain the odd higher harmonics of powerline frequencies; or vibrational noise from mechanical devices. The fundamental frequency of powerline hum may be removed during data acquisition with the use of notch filters. Unfortunately, notch filters do not discriminate signal and noise, attenuating both. They also distort adjacent frequencies by phase shifting. Finally, they attenuate only the fundamental mode of the powerline noise; higher harmonics and frequencies other than that of powerlines are not removed. Digital notch filters, applied during processing, have many of the same problems as analog filters applied in the field. The method described here removes hum of a particular frequency. Hum attributes are measured by discrete Fourier analysis, and the hum is canceled from the data by subtraction. Errors are slight and the result of the presence of (random) noise in the window or asynchrony of the hum and data sampling. Error is minimized by increasing window size or by resampling to a finer interval. Errors affect the degree of hum attenuation, not the signal. The residual is steady-state hum of the same frequency. ?? 1994.

  17. Spectral subtraction-based speech enhancement for cochlear implant patients in background noise

    NASA Astrophysics Data System (ADS)

    Yang, Li-Ping; Fu, Qian-Jie

    2005-03-01

    A single-channel speech enhancement algorithm utilizing speech pause detection and nonlinear spectral subtraction is proposed for cochlear implant patients in the present study. The spectral subtraction algorithm estimates the short-time spectral magnitude of speech by subtracting the estimated noise spectral magnitude from the noisy speech spectral magnitude. The artifacts produced by spectral subtraction (such as ``musical noise'') were significantly reduced by combining variance-reduced gain function and spectral flooring. Sentence recognition by seven cochlear implant subjects was tested under different noisy listening conditions (speech-shaped noise and 6-talker speech babble at +9, +6, +3, and 0 dB SNR) with and without the speech enhancement algorithm. For speech-shaped noise, performance for all subjects at all SNRs was significantly improved by the speech enhancement algorithm; for speech babble, performance was only modestly improved. The results suggest that the proposed speech enhancement algorithm may be beneficial for implant users in noisy listening. .

  18. Comparison study of intraosseous, central intravenous, and peripheral intravenous infusions of emergency drugs.

    PubMed

    Orlowski, J P; Porembka, D T; Gallagher, J M; Lockrem, J D; VanLente, F

    1990-01-01

    Intraosseous infusion of emergency drugs is a lifesaving alternative to intravenous administration when intravenous access cannot be rapidly established. We studied the comparative pharmacokinetics of the following six emergency drugs and solutions: epinephrine hydrochloride, 0.01 mg/kg; sodium bicarbonate, 1 mEq/kg; calcium chloride, 10 mg/kg; hydroxyethyl starch, 10 mL/kg; 50% dextrose in water, 250 mg/kg; and lidocaine hydrochloride, 1 mg/kg. Studies were conducted in normotensive, anesthetized dogs, with three animals studied with each of the drugs or solutions and each animal being treated with all three routes of administration (central intravenous, peripheral intravenous, and intraosseous) in randomized sequence. The effects of epinephrine were also assessed in a shock model. The intraosseous route of administration was comparable with the central and peripheral intravenous routes for all of the emergency drugs and solutions studied, with equivalent magnitudes of peak effect or drug level and equal or longer durations of action. Time to placement of the intraosseous needle varied from 15 seconds to 5 minutes, with a mean of 60 seconds. Time to placement of the needle varies with the skill and experience of the individual. With experience, all individuals could place the intraosseous needle in 60 seconds or less. The intraosseous route is comparable in effect to the central and peripheral intravenous routes of drug administration for epinephrine, sodium bicarbonate, hydroxyethyl starch, calcium chloride, 50% dextrose in water, and lidocaine and is a clinically feasible alternative when intravenous access will be critically delayed.

  19. Digital Discrimination

    ERIC Educational Resources Information Center

    Blansett, Jim

    2008-01-01

    In recent years, the Internet has become a digital commons of commerce and education. However, accessibility standards have often been overlooked online, and the digital equivalents to curb-cuts and other physical accommodations have only rarely been implemented to serve those with print disabilities. (A print disability can be a learning…

  20. Digitizing Preservation.

    ERIC Educational Resources Information Center

    Conway, Paul

    1994-01-01

    Discussion of digital imaging technology focuses on its potential use for preservation of library materials. Topics addressed include converting microfilm to digital; the high cost of conversion from paper or microfilm; quality; indexing; database management issues; incompatibility among imaging systems; longevity; cooperative pilot projects; and…