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Sample records for 64-slice mdct study

  1. A new approach to the assessment of lumen visibility of coronary artery stent at various heart rates using 64-slice MDCT

    PubMed Central

    Groen, J. M.; van Ooijen, P. M. A.; Oudkerk, M.

    2007-01-01

    Coronary artery stent lumen visibility was assessed as a function of cardiac movement and temporal resolution with an automated objective method using an anthropomorphic moving heart phantom. Nine different coronary stents filled with contrast fluid and surrounded by fat were scanned using 64-slice multi-detector computed tomography (MDCT) at 50–100 beats/min with the moving heart phantom. Image quality was assessed by measuring in-stent CT attenuation and by a dedicated tool in the longitudinal and axial plane. Images were scored by CT attenuation and lumen visibility and compared with theoretical scoring to analyse the effect of multi-segment reconstruction (MSR). An average increase in CT attenuation of 144 ± 59 HU and average diminished lumen visibility of 29 ± 12% was observed at higher heart rates in both planes. A negative correlation between image quality and heart rate was non-significant for the majority of measurements (P > 0.06). No improvement of image quality was observed in using MSR. In conclusion, in-stent CT attenuation increases and lumen visibility decreases at increasing heart rate. Results obtained with the automated tool show similar behaviour compared with attenuation measurements. Cardiac movement during data acquisition causes approximately twice as much blurring compared with the influence of temporal resolution on image quality. Electronic supplementary material The online version of this article (doi:10.1007/s00330-007-0568-8) contains supplementary material, which is available to authorized users. PMID:17429648

  2. Trabecular bone structure analysis in the osteoporotic spine using a clinical in vivo setup for 64-slice MDCT imaging: comparison to microCT imaging and microFE modeling.

    PubMed

    Issever, Ahi S; Link, Thomas M; Kentenich, Marie; Rogalla, Patrik; Schwieger, Karsten; Huber, Markus B; Burghardt, Andrew J; Majumdar, Sharmila; Diederichs, Gerd

    2009-09-01

    Assessment of trabecular microarchitecture may improve estimation of biomechanical strength, but visualization of trabecular bone structure in vivo is challenging. We tested the feasibility of assessing trabecular microarchitecture in the spine using multidetector CT (MDCT) on intact human cadavers in an experimental in vivo-like setup. BMD, bone structure (e.g., bone volume/total volume = BV/TV; trabecular thickness = Tb.Th; structure model index = SMI) and bone texture parameters were evaluated in 45 lumbar vertebral bodies using MDCT (mean in-plane pixel size, 274 microm(2); slice thickness, 500 microm). These measures were correlated with structure measures assessed with microCT at an isotropic spatial resolution of 16 microm and to microfinite element models (microFE) of apparent modulus and stiffness. MDCT-derived BMD and structure measures showed significant correlations to the density and structure obtained by microCT (BMD, R(2) = 0.86, p < 0.0001; BV/TV, R(2) = 0.64, p < 0.0001; Tb.Th, R(2) = 0.36, p < 0.01). When comparing microCT-derived measures with microFE models, the following correlations (p < 0.001) were found for apparent modulus and stiffness, respectively: BMD (R(2) = 0.58 and 0.66), BV/TV (R(2) = 0.44 and 0.58), and SMI (R(2) = 0.44 and 0.49). However, the overall highest correlation (p < 0.001) with microFE app. modulus (R(2) = 0.75) and stiffness (R(2) = 0.76) was achieved by the combination of QCT-derived BMD with the bone texture measure Minkowski Dimension. In summary, although still limited by its spatial resolution, trabecular bone structure assessment using MDCT is overall feasible. However, when comparing with microFE-derived bone properties, BMD is superior compared with single parameters for microarchitecture, and correlations further improve when combining with texture measures.

  3. Acute chest pain in emergency room. Preliminary findings with 40-64-slice CT ECG-gated of the whole chest.

    PubMed

    Coche, E

    2007-01-01

    ECG-gated MDCT of the entire chest represents the latest technical advance in the diagnostic work-up of atypical chest pain. The authors report their preliminary experience with the use of 40 and 64-slice CT in the emergency room and recommend to study only patients with moderate likelihood of coronary artery disease. ECG-gated MDCT of the entire chest will be preferentially performed on 64-slice MDCT rather than 40-slice MDCT because it enable to reduce the scan time (18 seconds versus 28 seconds acquisition time), the volume of contrast medium (82 mL + 15 mL versus 97 mL + 15 mL of highly concentrated contrast agent for a patient of 70 kgs) and radiation exposure (17 mSv versus 19 mSv). Approximately 1500 to 2000 of images are produced and need to be analysed on a dedicated workstation by a radiologist expert in cardiac and thoracic disorders. At the present time, only a few studies exist in the literature showing some promising results but further large clinical studies are needed before to implement such sophisticated protocol in emergency room.

  4. Integrated assessment of coronary anatomy and myocardial perfusion using a retractable SPECT camera combined with 64-slice CT: initial experience.

    PubMed

    Thilo, Christian; Schoepf, U Joseph; Gordon, Leonie; Chiaramida, Salvatore; Serguson, Jill; Costello, Philip

    2009-04-01

    We evaluated a prototype SPECT system integrated with multidetector row CT (MDCT) for obtaining complementary information on coronary anatomy and hemodynamic lesion significance. Twenty-five consecutive patients with known or suspected coronary artery disease (CAD) underwent routine SPECT myocardial perfusion imaging (MPI). All patients also underwent repeat MPI with a mobile SPECT unit which could be attached to a 64-slice MDCT system. Coronary CT angiography (cCTA) was performed without repositioning the patient. Investigational MPI was compared with routine MPI for detection of myocardial perfusion defects (PD). Two observers diagnosed presence or absence of CAD based on MPI alone, cCTA alone, and based on combined MPI and cCTA with fused image display. In 22/24 patients investigative MPI corresponded with routine MPI (r = 0.80). Stenosis >or= 50% at cCTA was detected in 6/24 patients. Six out of 24 patients had PD at regular MPI. Three of these six patients had no significant stenosis at cCTA. Three out of 19 patients with normal MPI studies had significant stenosis at cCTA. Our initial experience indicates that the integration of SPECT MPI with cCTA is technically feasible and enables the comprehensive evaluation of coronary artery anatomy and myocardial perfusion with a single instrumental setup.

  5. Hemodialysis fistula occlusion: demonstration with 64-slice CT angiography.

    PubMed

    Neyman, Edward G; Johnson, Pamela T; Fishman, Elliot K

    2006-01-01

    The speed and resolution of 64-slice CT have resulted in new applications for CT angiography (CTA) owing to rapid data acquisition during the arterial phase, improved visualization of small vessels, and lengthened anatomic coverage. Extremity CT angiography is one such region. This case report shows the utility of multislice CTA for the evaluation of hemodialysis graft dysfunction.

  6. Carotid stenosis evaluation by 64-slice CTA: comparison of NASCET, ECST and CC grading methods.

    PubMed

    Kılıçkap, Gülsüm; Ergun, Elif; Başbay, Elif; Koşar, Pınar; Kosar, Uğur

    2012-06-01

    Purpose is to evaluate the intraobserver and interobserver variability of the North American Symptomatic Carotid Endarterectomy Trial (NASCET), European Carotid Surgery Trial (ECST) and Common Carotid (CC) methods, which are used to measure the degree of ICA stenosis, using 64-slice CT angiography and to compare the measurements made by these three methods. 88 cases (111 carotid arteries) were included in the study. Carotid CTA was performed by a 64 slice scanner (Toshiba, Aqullion 64).Two radiologists measured the degree of carotid stenosis by using NASCET, ECST and CC methods. Intraobserver and interobserver variability of each method was determined by intraclass correlation coefficient (ICC), Bland-Altman plots and kappa and linear weighted kappa statistics. The relation between the measurements was assessed by correlation coefficient (with linear and quadratic methods). Correlation coefficients showed that there is linear correlation between the measurements made by the three methods. The degree of stenosis measured with the NASCET method had the lowest value, while the corresponding values measured with the ECST and CC methods were close to each other. ICC and Bland-Altman plots showed high intra and inter observer agreement for NASCET, ECST and CC methods whereas kappa statistics showed moderate to substantial agreement. CC method had slightly higher agreement when compared with the other two methods. Intra and interobserver agreement is high for NASCET, ECST and CC methods however CC method has a slightly higher reproducibility. There is linear correlation between the measurements made by the three methods.

  7. The value of 64-slice spiral CT perfusion imaging in the treatment of liver cancer with argon-helium cryoablation

    PubMed Central

    Lv, Yinggang; Jin, Yurong; Yan, Qiaohuan; Yuan, Dingling; Wang, Yanling; Li, Xianping; Shen, Yanfeng

    2016-01-01

    We analyzed the effectiveness of using 64-slice spiral computed tomography (CT) and perfusion imaging to guide argon-helium cryoablation treatment of liver cancer. In total, 60 cases of advanced hepatocellular carcinoma before surgery treated with argon-helium cryoablation were inlcuded in the present study. Retrospective summary of the 60 cases of metaphase and advanced liver cancer were used as the control group. The control group were treated using cryoablation with argon-helium knife. We used enhanced scanning with 64-slice spiral CT to define the extent of their lesions and prepared a plan of percutaneous cryoablation for the treatment. Intraoperatively, we used the dynamics of CT perfusion imaging to observe the frozen ablation range and decreased the rate of complications. After surgery, the patients were followed-up regularly by 64-slice CT. We used conventional X-ray, CT and magnetic resonance imaging (MRI) for pre-operative lateralization. Intraoperative X-ray or ultrasound guidance and follow-up with CT or MTI were added to determine the clinical effectiveness and prognosis. The results showed that the total effective rate was improved significantly and incidence rate of overall complications decreased markedly in the observation group. Following treatment, AFP decreased significantly while the total freezing area and time were reduced significantly. The median survival time was increased significantly in the observation group. The numeric values of hepatic arterial perfusion, portal vein perfusion and hepatic arterial perfusion index were all markedly lowered after treatment. Differences were statistically significant (P<0.05). In conclusion, the use of 64-slice spiral CT perfusion imaging may considerably improve the effects of liver cancer treatment using the argon-helium cryoablation. It extended the survival time and reduced complications. PMID:28105165

  8. 64 slice-coronary computed tomography sensitivity and specificity in the evaluation of coronary artery bypass graft stenosis: A meta-analysis.

    PubMed

    Barbero, Umberto; Iannaccone, Mario; d'Ascenzo, Fabrizio; Barbero, Cristina; Mohamed, Abdirashid; Annone, Umberto; Benedetto, Sara; Celentani, Dario; Gagliardi, Marco; Moretti, Claudio; Gaita, Fiorenzo

    2016-08-01

    A non-invasive approach to define grafts patency and stenosis in the follow-up of coronary artery bypass graft (CABG) patients may be an interesting alternative to coronary angiography. 64-slice-coronary computed tomography is nowadays a diffused non-invasive method that permits an accurate evaluation of coronary stenosis, due to a high temporal and spatial resolution. However, its sensitivity and specificity in CABG evaluation has to be clearly defined, since published studies used different protocols and scanners. We collected all studies investigating patients with stable symptoms and previous CABG and reporting the comparison between diagnostic performances of invasive coronary angiography and 64-slice-coronary computed tomography. As a result, sensitivity and specificity of 64-slice-coronary computed tomography for CABG occlusion were 0.99 (95% CI 0.97-1.00) and 0.99 (95% CI: 0.99-1.00) with an area under the curve (AUC) of 0.99. 64-slice-coronary computed tomography sensitivity and specificity for the presence of any CABG stenosis >50% were 0.98 (95% CI: 0.97-0.99) and 0.98 (95% CI: 0.96-0.98), while AUC was 0.99. At meta-regression, neither the age nor the time from graft implantation had effect on sensitivity and specificity of 64-slice-coronary computed tomography detection of significant CABG stenosis or occlusion. In conclusion 64-slice-coronary computed tomography confirmed its high sensitivity and specificity in CABG stenosis or occlusion evaluation.

  9. A 64-slice multi-detector CT scan could evaluate the change of the left atrial appendage thrombi of the atrial fibrillation patient, which was reduced by warfarin therapy.

    PubMed

    Takeuchi, Hidekazu

    2011-08-19

    Curable cause of stroke is the left atrial appendage (LAA) thrombi of atrial fibrillation (AF) patients. Some AF patients have the LAA thrombi. It is very important to cure AF patients by warfarin. Transoesophageal echocardiography (TOE) is the usual clinical tool to detect the LAA thrombi. Recently, a 64-slice multi-detector CT (64-MDCT) scan enables us to display the LAA thrombi more easily than TOE. I reported a case that a 64-MDCT scan had been used successfully in displaying the change of the LAA thrombi reduced by warfarin therapy. The size of the LAA thrombi was reduced from 25.2 mm × 19.3 mm (figure 1) to 22.1 mm × 14.8 mm (figure 2) after the 3-month warfarin therapy. It was useful to estimate the LAA thrombi by a 64-MDCT scan to estimate LAA thrombi itself and the change of LAA thrombi to evaluate the effectiveness of warfarin therapy.

  10. Non-invasive Detection of Aortic and Coronary Atherosclerosis in Homozygous Familial Hypercholesterolemia by 64 Slice Multi-detector Row Computed Tomography Angiography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Homozygous familial hypercholesterolemia (HoFH) is a rare disorder characterized by the early onset of atherosclerosis, often at the ostia of coronary arteries. In this study we document for the first time that aortic and coronary atherosclerosis can be detected using 64 slice multiple detector-row ...

  11. Non-invasive detection of aortic and coronary atherosclerosis in homozygous familial hypercholesterolemia by 64 slice multi-detector row computed tomography angiography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Homozygous familial hypercholesterolemia (HoFH) is a rare disorder characterized by the early onset of atherosclerosis, often at the ostia of coronary arteries. In this study we document for the first time that aortic and coronary atherosclerosis can be detected using 64 slice multiple detector row ...

  12. Diagnostic Capabilities of 64 Slice CT Coronography Compared to Classic in Coronary Disease Detection

    PubMed Central

    Sehovic, Sanja

    2013-01-01

    Introduction: Cardiovascular disease, among which the most common is coronary disease of the hearth are the main cause of death at middle aged persons in the majority of European countries. Percent of cardiovascular disease in overall mortality among our population is even more than 50%. Up to 55 years of live myocardial infarction is by 5-6 times more common among men, and up to age of 75 years that difference decreases to 2.5 times. Goal: The goal of this study is to determine the diagnostic value of 64 slices computerized tomography in detection of coronary disease compared to classic, invasive coronography. Material and methods: Study included 50 patients, of both genders, at average age of 60 years. Patients underwent CT coronography as well as classic coronography. Results: Our research prove that the sensitivity of MSCT coronography 92% with positive predictive value of 86%. Mayor difference was in the analysis of CX artery in the evaluation of significant and non-significant stenosis in application of these two methods. During the analysis of LAD and RCA artery there was no statistically significant difference in findings of these two methods. Conclusion: CT coronography is non-invasive, comfortable and reliable method in coronary disease diagnostics. Thanks to its high sensitivity and PPV it enables reliable exclusion of coronary disease and takes significant place in a cardiovascular diseases diagnostic algorithm. PMID:24167394

  13. Spectrum of Abdominal Aortic Disease in a Tertiary Health Care Setup: MDCT Based Observational Study

    PubMed Central

    Kumar, DG Santosh; Gadabanahalli, Karthik; Kalyanpur, Arjun

    2016-01-01

    Introduction Abdominal aortic disease is an important cause of clinical disability that requires early detection by imaging methods for prompt and effective management. Understanding regional disease pattern and prevalence has a bearing on healthcare management and resource planning. Non-invasive, conclusive imaging strategy plays an important role in the detection of disease. Multi-Detector Computed Tomography (MDCT) with its technological developments provides affordable, accurate and comprehensive imaging solution. Aim To evaluate regional demography of abdominal aortic disease spectrum detected using MDCT imaging data in a tertiary hospital. Materials and Methods A descriptive study was conducted based on MDCT imaging data of patients who were investigated with clinical diagnosis of abdominal aortic disease, from March 2008-2010, over a period of 24 months. Patients were examined with the contrast-enhanced MDCT examination. Morphological diagnosis of the aortic disease was based on changes in relative aortic caliber, luminal irregularity, presence of wall calcification, dissection or thrombus and evidence of major branch occlusion. Patients were categorized into four groups based on imaging findings. MDCT information and associated clinical parameters were examined and correlated to management of patient. Descriptive statistical data, namely mean, standard deviation and frequency of disease were evaluated. Results A total of 90 out of 210 patients (43%) were detected with the abdominal aortic abnormality defined by imaging criteria. Group I, comprising of patients with atherosclerosis –including those with complications, constituted 65.5% of the patients. Group II represented patients with aneurysms (45.5%). Group III, consisting of 32.2% of the patients, contained those with dissections. The rest of the patients, including patients with aorto-arteritis, were classified as group IV. Eight patients with aneurysm and one patient with aorto-arteritis were

  14. Assessments of Coronary Artery Visibility and Radiation Dose in Infants with Congenital Heart Disease on Cardiac 128-slice CT and on Cardiac 64-slice CT.

    PubMed

    Cui, Y; Huang, M; Zheng, J; Li, J; Liu, H; Liang, C

    2016-01-01

    The aim of this study was to compare the coronary artery visibility and radiation dose in infants with CHD on cardiac 128-slice CT and on cardiac 64-slice CT. The images of 200 patients were analyzed in this study, 100 patients were selected randomly from a group of 789 infants (<1 years old) with CHD undergoing 128-slice CT prospective ECG-triggered axial scan, and 100 were selected randomly from 911 infants with CHD undergoing 64-slice CT retrospective ECG-gated spiral scan. The visibility of coronary artery segments was graded on a four-point scale. The coronary arteries were considered to be detected or visible when grade was 2 or higher. The visibility of the coronary artery segments and the radiation dose was compared between the two groups. Except for the rate of LM (96 vs. 99%), the detection rates of the total, LAD, LCX, RCA, and the proximal segment of the RCA in the 256-slice CT group were significantly higher than those in the 64-slice CT group (51.7, 53.33, 33.67, 53.33, and 99 vs. 34.8, 34.33, 18, 30.67, and 75%, respectively). The counts of visibility score (4/3/2/1) for the LM and the proximal segment of the RCA were 62/22/12/4 and 56/20/17/7, respectively, in the 128-slice CT group and 17/42/30/1 and 9/30/38/25, respectively, in the 64-slice CT group. There were significant differences, especially for score 4 and 3, between the two groups. The radiation dose in the 128-slice CT group was significantly decreased than those in the 64-slice CT group (CTDIvol 1.88 ± 0.51 vs. 5.61 ± 0.63 mGy; SSDE 4.48 ± 1.15 vs. 13.97 ± 1.52 mGy; effective radiation dose 1.36 ± 0.44 vs. 4.06 ± 0.7 mSv). With reduced radiation dose, the visibility of the coronary artery in infants with CHD via prospective ECG-triggered mode on a 128-slice CT is superior to that of the 64-slice CT using retrospective ECG-gated spiral mode.

  15. 64-Slice Computed Tomographic Angiography for the Diagnosis of Intermediate Risk Coronary Artery Disease

    PubMed Central

    2010-01-01

    be less than 65 beats/min for the single source CTA machines and less than 80 beats/min for the dual source machines. To decrease heart rates to these levels, beta-blockers are often required. Although the accuracy of these two machines does not differ, the dual source machines can be utilized in a higher proportion of patients than the single source machines for patients with heart beats of up to 80 beats/min. Approximately 10% of patients are considered ineligible for CTA because of this inability to decrease heart rates to the required levels. Additional contra-indications include renal insufficiency as described above and atrial fibrillation, with approximately 10% of intermediate risk patients ineligible for CTA due these contraindications. The duration of the procedure may be between 1 and 1.5 hours, with about 15 minutes for the CTA and the remaining time for the preparation of the patient. CTA is licensed by Health Canada as a Class III device. Currently, two companies have licenses for 64-slice CT scanners, Toshiba Medical Systems Corporation (License 67604) and Philips Medical Systems (License 67599 and 73260). Research Questions How does the accuracy of CTA compare to the more invasive CA in the diagnosis of CAD in symptomatic patients at intermediate risk of the disease? How does the accuracy for CTA compare to other modalities in the detection of CAD? Research Methods Literature Search A literature search was performed on July 20, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 2004 until July 20, 2009. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any relevant studies not identified through the

  16. Beam hardening artifacts by dental implants: Comparison of cone-beam and 64-slice computed tomography scanners

    PubMed Central

    Esmaeili, Farzad; Johari, Masume; Haddadi, Pezhman

    2013-01-01

    Background: Cone beam computed tomography (CBCT) is an alternative to a computed tomography (CT) scan, which is appropriate for a wide range of craniomaxillofacial indications. The long-term use of metallic materials in dentistry means that artifacts caused by metallic restorations in the oral cavity should be taken into account when utilizing CBCT and CT scanners. The aim of this study was to quantitatively compare the beam hardening artifacts produced by dental implants between CBCT and a 64-Slice CT scanner. Materials and Methods: In this descriptive study, an implant drilling model similar to the human mandible was used in the present study. The implants (Dentis) were placed in the canine, premolar and molar areas. Three series of scans were provided from the implant areas using Somatom Sensation 64-slice and NewTom VGi (CBCT) CT scanners. Identical images were evaluated by three radiologists. The artifacts in each image were determined based on pre-determined criteria. Kruskal-Wallis test was used to compare mean values; Mann-Whitney U test was used for two-by-two comparisons when there was a statistical significance (P < 0.05). Results: The images of the two scanners had similar resolutions in axial sections (P = 0.299). In coronal sections, there were significant differences in the resolutions of the images produced by the two scanners (P < 0.001), with a higher resolution in the images produced by NewTom VGi scanner. On the whole, there were significant differences between the resolutions of the images produced by the two CT scanners (P < 0.001), with higher resolution in the images produced by NewTom VGi scanner in comparison to those of Somatom Sensation. Conclusion: Given the high quality of the images produced by NewTom VGi and the lower costs in comparison to CT, the use of the images of this scanner in dental procedures is recommended, especially in patients with extensive restorations, multiple prostheses and previous implants. PMID:24019808

  17. Dosimetric and image quality assessment of different acquisition protocols of a novel 64-slice CT scanner

    NASA Astrophysics Data System (ADS)

    Vite, Cristina; Mangini, Monica; Strocchi, Sabina; Novario, Raffaele; Tanzi, Fabio; Carrafiello, Gianpaolo; Conte, Leopoldo; Fugazzola, Carlo

    2006-03-01

    Dose and image quality assessment in computed tomography (CT) are almost affected by the vast variety of CT scanners (axial CT, spiral CT, low-multislice CT (2-16), high-multislice CT (32-64)) and imaging protocols in use. Very poor information is at the moment available on 64 slices CT scanners. Aim of this work is to assess image quality related to patient dose indexes and to investigate the achievable dose reduction for a commercially available 64 slices CT scanner. CT dose indexes (weighted computed tomography dose index, CTDI w and Dose Length Product, DLP) were measured with a standard CT phantom for the main protocols in use (head, chest, abdomen and pelvis) and compared with the values displayed by the scanner itself. The differences were always below 7%. All the indexes were below the Diagnostic Reference Levels defined by the European Council Directive 97/42. Effective doses were measured for each protocol with thermoluminescent dosimeters inserted in an anthropomorphic Alderson Rando phantom and compared with the same values computed by the ImPACT CT Patient Dosimetry Calculator software code and corrected by a factor taking in account the number of slices (from 16 to 64). The differences were always below 25%. The effective doses range from 1.5 mSv (head) to 21.8 mSv (abdomen). The dose reduction system of the scanner was assessed comparing the effective dose measured for a standard phantom-man (a cylinder phantom, 32 cm in diameter) to the mean dose evaluated on 46 patients. The standard phantom was considered as no dose reduction reference. The dose reduction factor range from 16% to 78% (mean of 46%) for all protocols, from 29% to 78% (mean of 55%) for chest protocol, from 16% to 76% (mean of 42%) for abdomen protocol. The possibility of a further dose reduction was investigated measuring image quality (spatial resolution, contrast and noise) as a function of CTDI w. This curve shows a quite flat trend decreasing the dose approximately to 90% and a

  18. A model for quantitative correction of coronary calcium scores on multidetector, dual source, and electron beam computed tomography for influences of linear motion, calcification density, and temporal resolution: A cardiac phantom study

    SciTech Connect

    Greuter, M. J. W.; Groen, J. M.; Nicolai, L. J.; Dijkstra, H.; Oudkerk, M.

    2009-11-15

    Purpose: The objective of this study is to quantify the influence of linear motion, calcification density, and temporal resolution on coronary calcium determination using multidetector computed tomography (MDCT), dual source CT (DSCT), and electron beam tomography (EBT) and to find a quantitative method which corrects for the influences of these parameters using a linear moving cardiac phantom. Methods: On a robotic arm with artificial arteries with four calcifications of increasing density, a linear movement was applied between 0 and 120 mm/s (step of 10 mm/s). The phantom was scanned five times on 64-slice MDCT, DSCT, and EBT using a standard acquisition protocol. The average Agatston, volume, and mass scores were determined for each velocity, calcification, and scanner. Susceptibility to motion was quantified using a cardiac motion susceptibility (CMS) index. Resemblance to EBT and physical volume and mass was quantified using a {Delta} index. Results: Increasing motion artifacts were observed at increasing velocities on all scanners, with increasing severity from EBT to DSCT to 64-slice MDCT. The calcium score showed a linear dependency on motion from which a correction factor could be derived. This correction factor showed a linear dependency on the mean calcification density with a good fit for all three scoring methods and all three scanners (0.73{<=}R{sup 2}{<=}0.95). The slope and offset of this correction factor showed a linear dependency on temporal resolution with a good fit for all three scoring methods and all three scanners (0.83{<=}R{sup 2}{<=}0.98). CMS was minimal for EBT and increasing values were observed for DSCT and highest values for 64-slice MDCT. CMS was minimal for mass score and increasing values were observed for volume score and highest values for Agatston score. For all densities and scoring methods DSCT showed on average the closest resemblance to EBT calcium scores. When using the correction factor, CMS index decreased on average by

  19. Evaluation of temporal windows for coronary artery bypass graft imaging with 64-slice CT.

    PubMed

    Desbiolles, Lotus; Leschka, Sebastian; Plass, André; Scheffel, Hans; Husmann, Lars; Gaemperli, Oliver; Garzoli, Elisabeth; Marincek, Borut; Kaufmann, Philipp A; Alkadhi, Hatem

    2007-11-01

    Temporal windows providing the best image quality of different segments and types of coronary artery bypass grafts (CABGs) with 64-slice computed tomography (CT) were evaluated in an experimental set-up. Sixty-four-slice CT with a rotation time of 330 ms was performed in 25 patients (four female; mean age 59.9 years). A total of 84 CABGs (62 individual and 22 sequential grafts) were evaluated, including 28 internal mammary artery (33.3%), one radial artery with sequential grafting (2.4%), and 54 saphenous vein grafts (64.3%). Ten data sets were reconstructed in 10% increments of the RR-interval. Each graft was separated into segments (proximal and distal anastomosis, and body), and CABG types were grouped according to target arteries. Two readers independently assessed image quality of each CABG segment in each temporal window. Diagnostic image quality was found with good inter-observer agreement (kappa=0.62) in 98.5% (202/205) of all graft segments. Image quality was significantly better for saphenous vein grafts versus arterial grafts (P<0.001) and for distal anastomosis to the right coronary compared with other target coronary arteries (P<0.05). Overall, best image quality was found at 60%. Image quality of proximal segments did not significantly vary with the temporal window, whereas for all other segments image quality was significantly better at 60% compared with other temporal windows (P<0.05). Sixty-four-slice CT provides best image quality of various segments and types of CABG at 60% of the RR-interval.

  20. 64-Slice spiral computed tomography and three-dimensional reconstruction in the diagnosis of cystic pancreatic tumors

    PubMed Central

    WEN, ZHAOXIA; YAO, FENGQING; WANG, YUXING

    2016-01-01

    The present study aimed to describe the characteristics of cystic pancreatic tumors using computed tomography (CT) and to evaluate the diagnostic accuracy (DA) of post-imaging three-dimensional (3D) reconstruction. Clinical and imaging data, including multi-slice spiral CT scans, enhanced scans and multi-faceted reconstruction, from 30 patients with pathologically confirmed cystic pancreatic tumors diagnosed at the Linyi People's Hospital between August 2008 and June 2014 were retrospectively analyzed. Following the injection of Ultravist® 300 contrast agent, arterial, portal venous and parenchymal phase scans were obtained at 28, 60 and 150 sec, respectively, and 3D reconstructions of the CT images were generated. The average age of the patients was 38.4 years (range, 16–77 years), and the cohort included 5 males and 25 females (ratio, 1:5). The patients included 8 cases of mucinous cystadenoma (DA), 80%]; 9 cases of cystadenocarcinoma (DA, 84%); 6 cases of serous cystadenoma (DA, 100%); 3 cases of solid pseudopapillary tumor (DA, 100%); and 4 cases of intraductal papillary mucinous neoplasm (DA, 100%). 3D reconstructions of CT images were generated and, in the 4 cases of intraductal papillary mucinous neoplasm, the tumor was connected to the main pancreatic duct and multiple mural nodules were detected in one of these cases. The DA of the 3D-reconstructed images of cystic pancreatic tumors was 89.3%. The 64-slice spiral CT and 3D-reconstructed CT images facilitated the visualization of cystic pancreatic tumor characteristics, in particular the connections between the tumor and the main pancreatic duct. In conclusion, the 3D reconstruction of multi-slice CT data may provide an important source of information for the surgical team, in combination with the available clinical data. PMID:27073473

  1. A Numerical Study of Water Loss Rate Distributions in MDCT-based Human Airway Models

    PubMed Central

    Wu, Dan; Miyawaki, Shinjiro; Tawhai, Merryn H.; Hoffman, Eric A.; Lin, Ching-Long

    2015-01-01

    Both three-dimensional (3D) and one-dimensional (1D) computational fluid dynamics (CFD) methods are applied to study regional water loss in three multi-detector row computed-tomography (MDCT)-based human airway models at the minute ventilations of 6, 15 and 30 L/min. The overall water losses predicted by both 3D and 1D models in the entire respiratory tract agree with available experimental measurements. However, 3D and 1D models reveal different regional water loss rate distributions due to the 3D secondary flows formed at bifurcations. The secondary flows cause local skewed temperature and humidity distributions on inspiration acting to elevate the local water loss rate; and the secondary flow at the carina tends to distribute more cold air to the lower lobes. As a result, the 3D model predicts that the water loss rate first increases with increasing airway generation, and then decreases as the air approaches saturation, while the 1D model predicts a monotonic decrease of water loss rate with increasing airway generation. Moreover, the 3D (or 1D) model predicts relatively higher water loss rates in lower (or upper) lobes. The regional water loss rate can be related to the non-dimensional wall shear stress (τ*) by the non-dimensional mass transfer coefficient (h0*) as h0* = 1.15 τ*0.272, R = 0.842. PMID:25869455

  2. Influence of radiation dose and reconstruction algorithm in MDCT assessment of airway wall thickness: A phantom study

    SciTech Connect

    Gomez-Cardona, Daniel; Nagle, Scott K.; Li, Ke; Chen, Guang-Hong; Robinson, Terry E.

    2015-10-15

    Purpose: Wall thickness (WT) is an airway feature of great interest for the assessment of morphological changes in the lung parenchyma. Multidetector computed tomography (MDCT) has recently been used to evaluate airway WT, but the potential risk of radiation-induced carcinogenesis—particularly in younger patients—might limit a wider use of this imaging method in clinical practice. The recent commercial implementation of the statistical model-based iterative reconstruction (MBIR) algorithm, instead of the conventional filtered back projection (FBP) algorithm, has enabled considerable radiation dose reduction in many other clinical applications of MDCT. The purpose of this work was to study the impact of radiation dose and MBIR in the MDCT assessment of airway WT. Methods: An airway phantom was scanned using a clinical MDCT system (Discovery CT750 HD, GE Healthcare) at 4 kV levels and 5 mAs levels. Both FBP and a commercial implementation of MBIR (Veo{sup TM}, GE Healthcare) were used to reconstruct CT images of the airways. For each kV–mAs combination and each reconstruction algorithm, the contrast-to-noise ratio (CNR) of the airways was measured, and the WT of each airway was measured and compared with the nominal value; the relative bias and the angular standard deviation in the measured WT were calculated. For each airway and reconstruction algorithm, the overall performance of WT quantification across all of the 20 kV–mAs combinations was quantified by the sum of squares (SSQs) of the difference between the measured and nominal WT values. Finally, the particular kV–mAs combination and reconstruction algorithm that minimized radiation dose while still achieving a reference WT quantification accuracy level was chosen as the optimal acquisition and reconstruction settings. Results: The wall thicknesses of seven airways of different sizes were analyzed in the study. Compared with FBP, MBIR improved the CNR of the airways, particularly at low radiation dose

  3. Image Quality and Radiation Dose for Prospectively Triggered Coronary CT Angiography: 128-Slice Single-Source CT versus First-Generation 64-Slice Dual-Source CT

    NASA Astrophysics Data System (ADS)

    Gu, Jin; Shi, He-Shui; Han, Ping; Yu, Jie; Ma, Gui-Na; Wu, Sheng

    2016-10-01

    This study sought to compare the image quality and radiation dose of coronary computed tomography angiography (CCTA) from prospectively triggered 128-slice CT (128-MSCT) versus dual-source 64-slice CT (DSCT). The study was approved by the Medical Ethics Committee at Tongji Medical College of Huazhong University of Science and Technology. Eighty consecutive patients with stable heart rates lower than 70 bpm were enrolled. Forty patients were scanned with 128-MSCT, and the other 40 patients were scanned with DSCT. Two radiologists independently assessed the image quality in segments (diameter >1 mm) according to a three-point scale (1: excellent; 2: moderate; 3: insufficient). The CCTA radiation dose was calculated. Eighty patients with 526 segments in the 128-MSCT group and 544 segments in the DSCT group were evaluated. The image quality 1, 2 and 3 scores were 91.6%, 6.9% and 1.5%, respectively, for the 128-MSCT group and 97.6%, 1.7% and 0.7%, respectively, for the DSCT group, and there was a statistically significant inter-group difference (P ≤ 0.001). The effective doses were 3.0 mSv in the 128-MSCT group and 4.5 mSv in the DSCT group (P ≤ 0.001). Compared with DSCT, CCTA with prospectively triggered 128-MSCT had adequate image quality and a 33.3% lower radiation dose.

  4. Body physique and heart rate variability determine the occurrence of stair-step artefacts in 64-slice CT coronary angiography with prospective ECG-triggering.

    PubMed

    Husmann, Lars; Herzog, Bernhard A; Burkhard, Nina; Tatsugami, Fuminari; Valenta, Ines; Gaemperli, Oliver; Wyss, Christophe A; Landmesser, Ulf; Kaufmann, Philipp A

    2009-07-01

    The purpose of this study was to describe and characterize the frequency and extent of stair-step artefacts in computed tomography coronary angiography (CTCA) with prospective electrocardiogram (ECG)-triggering and to identify their determinants. One hundred and forty three consecutive patients (55 women, mean age 57 +/- 13 years) underwent 64-slice CTCA using prospective ECG-triggering. Occurrence of stair-step artefacts in CTCA of the thoracic wall and the coronary arteries was determined and maximum offset was measured. If stair-step artefacts occurred in both cases, a difference between thoracic wall and coronary artery offset of 0.6 mm or greater was attributed to additional motion of the heart. Mean effective radiation dose was 2.1 +/- 0.7 mSv (range 1.0-3.5 mSv). Eighty-nine patients (62%) had stair-step artefacts in CTCA of the coronary arteries (mean offset of 1.7 +/- 1.1 mm), while only 77 patients had thoracic wall stair-step artefacts (mean offset of 1.0 +/- 0.3 mm; significantly different, P < 0.001). Stair-step artefacts in CTCA of the thoracic wall were determined by BMI and weight (P < 0.01), while artefacts in CTCA of the coronary arteries were associated with heart rate variability (P < 0.05). Stair-step artefacts in CTCA with prospective ECG-triggering are determined by (a) motion of the entire patient during table travel, particularly in large patients and (b) by motion of the heart, particularly when heart rates are variable.

  5. Experimental assessment of the influence of beam hardening filters on image quality and patient dose in volumetric 64-slice X-ray CT scanners.

    PubMed

    Ay, Mohammad Reza; Mehranian, Abolfazl; Maleki, Asghar; Ghadiri, Hossien; Ghafarian, Pardis; Zaidi, Habib

    2013-05-01

    Beam hardening filters have long been employed in X-ray Computed Tomography (CT) to preferentially absorb soft and low-energy X-rays having no or little contribution to image formation, thus allowing the reduction of patient dose and beam hardening artefacts. In this work, we studied the influence of additional copper (Cu) and aluminium (Al) flat filters on patient dose and image quality and seek an optimum filter thickness for the GE LightSpeed VCT 64-slice CT scanner using experimental phantom measurements. Different thicknesses of Cu and Al filters (0.5-1.6mm Cu, 0.5-4mm Al) were installed on the scanner's collimator. A planar phantom consisting of 13 slabs of Cu having different thicknesses was designed and scanned to assess the impact of beam filtration on contrast in the intensity domain (CT detector's output). To assess image contrast and image noise, a cylindrical phantom consisting of a polyethylene cylinder having 16 holes filled with different concentrations of K2HPO4 solution mimicking different tissue types was used. The GE performance and the standard head CT dose index (CTDI) phantoms were also used to assess image resolution characterized by the modulation transfer function (MTF) and patient dose defined by the weighted CTDI. A 100mm pencil ionization chamber was used for CTDI measurement. Finally, an optimum filter thickness was determined from an objective figure of merit (FOM) metric. The results show that the contrast is somewhat compromised with filter thickness in both the planar and cylindrical phantoms. The contrast of the K2HPO4 solutions in the cylindrical phantom was degraded by up to 10% for a 0.68mm Cu filter and 6% for a 4.14mm Al filter. It was shown that additional filters increase image noise which impaired the detectability of low density K2HPO4 solutions. It was found that with a 0.48mm Cu filter the 50% MTF value is shifted by about 0.77lp/cm compared to the case where the filter is not used. An added Cu filter with approximately

  6. A numerical study of heat and water vapor transfer in MDCT-based human airway models.

    PubMed

    Wu, Dan; Tawhai, Merryn H; Hoffman, Eric A; Lin, Ching-Long

    2014-10-01

    A three-dimensional (3D) thermo-fluid model is developed to study regional distributions of temperature and water vapor in three multi-detector row computed-tomography-based human airways with minute ventilations of 6, 15 and 30 L/min. A one-dimensional (1D) model is also solved to provide necessary initial and boundary conditions for the 3D model. Both 3D and 1D predicted temperature distributions agree well with available in vivo measurement data. On inspiration, the 3D cold high-speed air stream is split at the bifurcation to form secondary flows, with its cold regions biased toward the inner wall. The cold air flowing along the wall is warmed up more rapidly than the air in the lumen center. The repeated splitting pattern of air streams caused by bifurcations acts as an effective mechanism for rapid heat and mass transfer in 3D. This provides a key difference from the 1D model, where heating relies largely on diffusion in the radial direction, thus significantly affecting gradient-dependent variables, such as energy flux and water loss rate. We then propose the correlations for respective heat and mass transfer in the airways of up to 6 generations: [Formula: see text] and [Formula: see text], where Nu is the Nusselt number, Sh is the Sherwood number, Re is the branch Reynolds number, D a is the airway equivalent diameter, and [Formula: see text] is the tracheal equivalent diameter.

  7. The spectrum of facial fractures in motor vehicle accidents: an MDCT study of 374 patients.

    PubMed

    Peltola, Elina M; Koivikko, Mika P; Koskinen, Seppo K

    2014-04-01

    Road traffic accidents are a major health problem worldwide resulting frequently in maxillofacial injuries. The purpose of the study was to assess the incidence and spectrum of facial fractures in patients involved in a motor vehicle accident (MVA). Using picture archiving and communication system, all requests for suspected facial trauma were retrieved during a 62-month period; 374 met the inclusion criteria. Two researchers interpreted the multidetector computed tomography images by consensus. The motor vehicles involved were divided into two groups: those involving a passenger car or a larger vehicle and those involving a motorized two-wheeler. Furthermore, the motor vehicle accidents were divided into collisions and run-off-road accidents. Of the 374 patients (aged 15-80, mean 34), 271 (72 %) were male and 103 (28 %) female. Of all patients, 262 (70 %) had a facial or skull base fracture; of these, multiple separate fractures were present in 56 %. Nasal fractures were the most common fractures followed by orbital, skull base, and maxillary fractures. Frontal bone, LeFort, and zygomatic arch fractures were always accompanied by other fractures. Fractures were more frequent in the group of collisions compared with run-off-road accidents. In the two-wheeled group, only 15 % did not have facial or skull base fractures. Fractures often occur in multitudes as 39 % of all patients have multiple facial or skull bone fractures, and thus, emergency radiologists should be familiar with the complexity of the injuries. Negative clear sinus sign and low-energy sentinel injuries should be trusted as indications of undetected injuries in MVA victims.

  8. Effect of Heart Rate and Body Mass Index on the Interscan and Interobserver Variability of Coronary Artery Calcium Scoring at Prospective ECG-Triggered 64-Slice CT

    PubMed Central

    Matsuura, Noriaki; Yamamoto, Hideya; Kiguchi, Masao; Fujioka, Chikako; Kitagawa, Toshiro; Ito, Katsuhide

    2009-01-01

    Objective To test the effects of heart rate, body mass index (BMI) and noise level on interscan and interobserver variability of coronary artery calcium (CAC) scoring on a prospective electrocardiogram (ECG)-triggered 64-slice CT. Materials and Methods One hundred and ten patients (76 patients with CAC) were scanned twice on prospective ECG-triggered scans. The scan parameters included 120 kV, 82 mAs, a 2.5 mm thickness, and an acquisition center at 45% of the RR interval. The interscan and interobserver variability on the CAC scores (Agatston, volume, and mass) was calculated. The factors affecting the variability were determined by plotting it against heart rate, BMI, and noise level (defined as the standard deviation: SD). Results The estimated effective dose was 1.5 ± 0.2 mSv. The mean heart rate was 63 ± 12 bpm (range, 44-101 bpm). The patient BMIs were 24.5 ± 4.5 kg/m2 (range, 15.5-42.3 kg/m2). The mean and median interscan variabilities were 11% and 6%, respectively by volume, and 11% and 6%, respectively, by mass. Moreover, the mean and median of the algorithms were lower than the Agatston algorithm (16% and 9%, respectively). The mean and median interobserver variability was 10% and 4%, respectively (average of algorithms). The mean noise levels were 15 ± 4 Hounsfield unit (HU) (range, 8-25 HU). The interscan and interobserver variability was not correlated with heart rate, BMI, or noise level. Conclusion The interscan and interobserver variability of CAC on a prospective ECG-triggered 64-slice CT with high image quality and 45% of RR acquisition is not significantly affected by heart rate, BMI, or noise level. The volume or mass algorithms show reduced interscan variability compared to the Agatston scoring (p < 0.05). PMID:19568461

  9. The role of 64-slice CT following perfusion with iohexol via the hepatopancreatic ampulla in assessing pancreaticobiliary junctions.

    PubMed

    Guo, Wan-Liang; Bai, Xue-Jie; Huang, Shun-Gen; Fang, Lin; Wang, Jian

    2015-07-01

    The aim of this study was to delineate the structure of the pancreatic and biliary ducts in premature infants using a novel imaging method. The duodenal papillae of 30 premature infant cadavers were dissected. The pancreatic and biliary ducts were visualized using 64-detector multislice spiral computed tomography (MSCT). Contrast agent was injected into the duodenal papilla via the hepatopancreatic ampulla of Vater. MSCT scanning revealed both the pancreatic and biliary ducts as well as the common channel in 18 cases. The bile duct was visualized in the remaining 12 cases. Four patterns of the pancreaticobiliary ductal junction were noted: Y-type (73.3%), U-type (13.3%), V-type (6.7%), and II-type (6.7%). The results showed that MSCT and three-dimensional reconstruction can be used to visualize the junction pattern and common channel of the pancreatic and biliary ducts, and the structure of the surrounding tissue, in premature infants.

  10. [Examination of the effectiveness of heart rate control using intravenous β-blocker in 64-slice coronary computed tomography angiography].

    PubMed

    Yamaguchi, Takayoshi; Takahashi, Daichi; Nakagawa, Shingo; Morita, Mari; Noda, Rie; Nakamura, Yoko; Igarashi, Keiichi

    2012-01-01

    The purpose of this study is to clarify the effectiveness of the use of β-blocker in coronary computed tomography angiography (CCTA). In 1783 patients, heart rate was controlled by propranolol injection to patients with heart rates of 61 bpm or more. As a result, the scan heart rate (58.8±6.5 bpm) decreased significantly compared with the initial heart rate (72.7±9.4 bpm). Prospective gating method was used by 61.9% including 64.3% of the intravenous β-blocker injection group. Moreover, daily use of oral β-blocker had influence on reduction of the scan heart rate (daily use group: 60.1±6.5 bpm vs. unuse group: 58.5±6.3 bpm p<0.01). When we evaluated the image quality of CCTA by the score, the improvement of the score was obviously admitted by 65 bpm or less of the scan heart rate. The ratio of scan heart rate that was controlled by 65 bpm or less was decreased in the initial heart rate groups that were 81 bpm or more. The incidence of adverse reactions by the propranolol injection was few, and these instances only involved slight symptoms. Therefore, heart rate control with the use of β-blocker is useful for the image quality improvement of CCTA. This form of treatment can be safely enforced.

  11. In-Vivo Assessment of Femoral Bone Strength Using Finite Element Analysis (FEA) Based on Routine MDCT Imaging: A Preliminary Study on Patients with Vertebral Fractures

    PubMed Central

    Liebl, Hans; Garcia, Eduardo Grande; Holzner, Fabian; Noel, Peter B.; Burgkart, Rainer; Rummeny, Ernst J.; Baum, Thomas; Bauer, Jan S.

    2015-01-01

    Purpose To experimentally validate a non-linear finite element analysis (FEA) modeling approach assessing in-vitro fracture risk at the proximal femur and to transfer the method to standard in-vivo multi-detector computed tomography (MDCT) data of the hip aiming to predict additional hip fracture risk in subjects with and without osteoporosis associated vertebral fractures using bone mineral density (BMD) measurements as gold standard. Methods One fresh-frozen human femur specimen was mechanically tested and fractured simulating stance and clinically relevant fall loading configurations to the hip. After experimental in-vitro validation, the FEA simulation protocol was transferred to standard contrast-enhanced in-vivo MDCT images to calculate individual hip fracture risk each for 4 subjects with and without a history of osteoporotic vertebral fractures matched by age and gender. In addition, FEA based risk factor calculations were compared to manual femoral BMD measurements of all subjects. Results In-vitro simulations showed good correlation with the experimentally measured strains both in stance (R2 = 0.963) and fall configuration (R2 = 0.976). The simulated maximum stress overestimated the experimental failure load (4743 N) by 14.7% (5440 N) while the simulated maximum strain overestimated by 4.7% (4968 N). The simulated failed elements coincided precisely with the experimentally determined fracture locations. BMD measurements in subjects with a history of osteoporotic vertebral fractures did not differ significantly from subjects without fragility fractures (femoral head: p = 0.989; femoral neck: p = 0.366), but showed higher FEA based risk factors for additional incident hip fractures (p = 0.028). Conclusion FEA simulations were successfully validated by elastic and destructive in-vitro experiments. In the subsequent in-vivo analyses, MDCT based FEA based risk factor differences for additional hip fractures were not mirrored by according BMD measurements. Our

  12. Radiation dose measurement for various parameters in MDCT

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Lae; Kim, Hee-Joung; Jeon, Seong Su; Cho, Hyo-Min; Nam, So Ra; Jung, Ji-Young

    2008-03-01

    The MDCT parameters affecting radiation dose include tube voltage, tube current, change of beam collimation, and size of the human body. The purpose of this study was to measure and evaluate radiation dose for MDCT parameters. A comparative analysis of the radiation dose according to before and after the calibration of the ionization chamber was performed. The ionization chamber was used for measuring radiation dose in the MDCT, as well as of CTDI W according to temperature and pressure correction factors in the CT room. As a result, the patient dose of CTDI W values linearly increased as tube voltage and current were increased, and nonlinearly decreased as beam collimation was increased. And the CTDI W value which was reflected calibration factors, as well as correction factors of temperature and pressure, was found to be greater by the range of 0.479 ~ 3.162 mGy in effective radiation dose than the uncorrected value. Also, Under the abdomen routine CT conditions used in hospitals, patient exposure dose showed a difference of a maximum of 0.7 mSv between before and after the application of such factors. These results imply that the calibration of the ion chamber, and the application of temperature and pressure of the CT room are crucial in measuring and calculating patient exposure dose.

  13. Reducing radiation dose to selected organs by selecting the tube start angle in MDCT helical scans: A Monte Carlo based study

    SciTech Connect

    Zhang Di; Zankl, Maria; DeMarco, John J.; Cagnon, Chris H.; Angel, Erin; Turner, Adam C.; McNitt-Gray, Michael F.

    2009-12-15

    Purpose: Previous work has demonstrated that there are significant dose variations with a sinusoidal pattern on the peripheral of a CTDI 32 cm phantom or on the surface of an anthropomorphic phantom when helical CT scanning is performed, resulting in the creation of ''hot'' spots or ''cold'' spots. The purpose of this work was to perform preliminary investigations into the feasibility of exploiting these variations to reduce dose to selected radiosensitive organs solely by varying the tube start angle in CT scans. Methods: Radiation dose to several radiosensitive organs (including breasts, thyroid, uterus, gonads, and eye lenses) resulting from MDCT scans were estimated using Monte Carlo simulation methods on voxelized patient models, including GSF's Baby, Child, and Irene. Dose to fetus was also estimated using four pregnant female models based on CT images of the pregnant patients. Whole-body scans were simulated using 120 kVp, 300 mAs, both 28.8 and 40 mm nominal collimations, and pitch values of 1.5, 1.0, and 0.75 under a wide range of start angles (0 deg. - 340 deg. in 20 deg. increments). The relationship between tube start angle and organ dose was examined for each organ, and the potential dose reduction was calculated. Results: Some organs exhibit a strong dose variation, depending on the tube start angle. For small peripheral organs (e.g., the eye lenses of the Baby phantom at pitch 1.5 with 40 mm collimation), the minimum dose can be 41% lower than the maximum dose, depending on the tube start angle. In general, larger dose reductions occur for smaller peripheral organs in smaller patients when wider collimation is used. Pitch 1.5 and pitch 0.75 have different mechanisms of dose reduction. For pitch 1.5 scans, the dose is usually lowest when the tube start angle is such that the x-ray tube is posterior to the patient when it passes the longitudinal location of the organ. For pitch 0.75 scans, the dose is lowest when the tube start angle is such that the x

  14. Quantitative analysis of the central-chest lymph nodes based on 3D MDCT image data

    NASA Astrophysics Data System (ADS)

    Lu, Kongkuo; Bascom, Rebecca; Mahraj, Rickhesvar P. M.; Higgins, William E.

    2009-02-01

    Lung cancer is the leading cause of cancer death in the United States. In lung-cancer staging, central-chest lymph nodes and associated nodal stations, as observed in three-dimensional (3D) multidetector CT (MDCT) scans, play a vital role. However, little work has been done in relation to lymph nodes, based on MDCT data, due to the complicated phenomena that give rise to them. Using our custom computer-based system for 3D MDCT-based pulmonary lymph-node analysis, we conduct a detailed study of lymph nodes as depicted in 3D MDCT scans. In this work, the Mountain lymph-node stations are automatically defined by the system. These defined stations, in conjunction with our system's image processing and visualization tools, facilitate lymph-node detection, classification, and segmentation. An expert pulmonologist, chest radiologist, and trained technician verified the accuracy of the automatically defined stations and indicated observable lymph nodes. Next, using semi-automatic tools in our system, we defined all indicated nodes. Finally, we performed a global quantitative analysis of the characteristics of the observed nodes and stations. This study drew upon a database of 32 human MDCT chest scans. 320 Mountain-based stations (10 per scan) and 852 pulmonary lymph nodes were defined overall from this database. Based on the numerical results, over 90% of the automatically defined stations were deemed accurate. This paper also presents a detailed summary of central-chest lymph-node characteristics for the first time.

  15. Robust extraction of the aorta and pulmonary artery from 3D MDCT image data

    NASA Astrophysics Data System (ADS)

    Taeprasartsit, Pinyo; Higgins, William E.

    2010-03-01

    Accurate definition of the aorta and pulmonary artery from three-dimensional (3D) multi-detector CT (MDCT) images is important for pulmonary applications. This work presents robust methods for defining the aorta and pulmonary artery in the central chest. The methods work on both contrast enhanced and no-contrast 3D MDCT image data. The automatic methods use a common approach employing model fitting and selection and adaptive refinement. During the occasional event that more precise vascular extraction is desired or the method fails, we also have an alternate semi-automatic fail-safe method. The semi-automatic method extracts the vasculature by extending the medial axes into a user-guided direction. A ground-truth study over a series of 40 human 3D MDCT images demonstrates the efficacy, accuracy, robustness, and efficiency of the methods.

  16. Segmentation of the central-chest lymph nodes in 3D MDCT images.

    PubMed

    Lu, Kongkuo; Higgins, William E

    2011-09-01

    Central-chest lymph nodes play a vital role in lung-cancer staging. The definition of lymph nodes from three-dimensional (3D) multidetector computed-tomography (MDCT) images, however, remains an open problem. We propose two methods for computer-based segmentation of the central-chest lymph nodes from a 3D MDCT scan: the single-section live wire and the single-click live wire. For the single-section live wire, the user first applies the standard live wire to a single two-dimensional (2D) section after which automated analysis completes the segmentation process. The single-click live wire is similar but is almost completely automatic. Ground-truth studies involving human 3D MDCT scans demonstrate the robustness, efficiency, and intra-observer and inter-observer reproducibility of the methods.

  17. Intraindividual comparison of gadolinium- and iodine-enhanced 64-slice multidetector CT pulmonary angiography for the detection of pulmonary embolism in a porcine model.

    PubMed

    Henes, Frank Oliver Gerhard; Groth, Michael; Begemann, Philipp G C; Adam, Gerhard; Regier, Marc

    2011-06-01

    This study is an evaluation of the diagnostic accuracy of gadolinium-enhanced computed tomography pulmonary angiography (CTPA) for the detection of pulmonary embolism (PE) in comparison with iodine-enhanced CTPA. PE was induced in five anesthetized pigs by administration of blood clots through an 11-F catheter inside the jugular vein. Animals underwent CTPA in breathhold with i.v. bolus injection of 50 ml gadopentetate dimeglumine (0.4 mmol/kg, 4 ml/s). Subsequently, CTPA was performed using the same imaging parameters but under administration of 70 ml nonionic iodinated contrast material (400 mg/ml, 4 ml/s). All images were reconstructed with 1 mm slice thickness. A consensus readout of the iodium-enhanced CTPAs by both radiologists served as reference standard. Gadolinium-enhanced CTPAs were evaluated independently by two experienced radiologists, and differences in detection rate between both contrast agents were assessed on a per embolus basis using the Wilcoxon signed-rank test. Interobserver agreement was determined by calculation of қ values. PE was diagnosed independently by both readers in all five pigs by the use of gadolinium-enhanced CTPA. Out of 60 pulmonary emboli detected in the iodine-enhanced scans, 47 (78.3%; reader 1) and 44 (62.8%; reader 2) emboli were detected by the use of gadolinium. All 13 (100%) emboli in lobar arteries (by both readers) and 26 (reader 1) and 25 (reader 2) out of 27 emboli (96.3% and 92.6%) in segmental arteries were detected by the use of the gadolinium-enhanced CTPA. In subsegmental arteries, only 8 (40%; reader 1) and 6 (30%; reader 2) out of 20 emboli were detected by the gadolinium-enhanced CTPA. By comparing both scans on a per vessel basis (Wilcoxon test), Gd-enhanced CTPA was significantly inferior in emboli detection on subsegmental level (P < 0.0001). The interobserver agreement was excellent on lobar and segmental level (қ = 1.0 and 0.93, respectively), whereas readers only reached moderate

  18. Preoperative quantification of aortic valve stenosis: comparison of 64-slice computed tomography with transesophageal and transthoracic echocardiography and size of implanted prosthesis.

    PubMed

    Mizia-Stec, Katarzyna; Pysz, Piotr; Jasiński, Marek; Adamczyk, Tomasz; Drzewiecka-Gerber, Agnieszka; Chmiel, Artur; Krejca, Michał; Bochenek, Andrzej; Woś, Stanisław; Sosnowski, Maciej; Gąsior, Zbigniew; Trusz-Gluza, Maria; Tendera, Michał

    2012-02-01

    Precise measurements of aortic complex diameters are essential for preoperative examinations of patients with aortic stenosis (AS) scheduled for aortic valve (AV) replacement. We aimed to prospectively compare the accuracy of transthoracic echocardiography (TTE), transoesophageal echocardiography (TEE) and multi-slice computed tomography (MSCT) measurements of the AV complex and to analyze the role of the multi-modality aortic annulus diameter (AAd) assessment in the selection of the optimal prosthesis to be implanted in patients surgically treated for degenerative AS. 20 patients (F/M: 3/17; age: 69 ± 6.5 years) with severe degenerative AS were enrolled into the study. TTE, TEE and MSCT including AV calcium score (AVCS) assessment were performed in all patients. The values of AAd obtained in the long AV complex axis (TTE, TEE, MSCT) and in multiplanar perpendicular imaging (MSCT) were compared to the size of implanted prosthesis. The mean AAd was 24 ± 3.6 mm using TTE, 26 ± 4.2 mm using TEE, and 26.9 ± 3.2 in MSCT (P = 0.04 vs. TTE). The mean diameter of the left ventricle out-flow tract in TTE (19.9 ± 2.7 mm) and TEE (19.5 ± 2.7 mm) were smaller than in MSCT (24.9 ± 3.3 mm, P < 0.001 for both). The mean size of implanted prosthesis (22.2 ± 2.3 mm) was significantly smaller than the mean AAd measured by TTE (P = 0.0039), TEE (P = 0.0004), and MSCT (P < 0.0001). The implanted prosthesis size correlated significantly to the AAd: r = 0.603, P = 0.005 for TTE, r = 0.592, P = 0.006 for TEE, and r = 0.791, P < 0.001 for MSCT. Obesity and extensive valve calcification (AV calcium score ≥ 3177Ag.U.) were identified as potent factors that caused a deterioration of both TTE and MSCT performance. The accuracy of AAd measurements in TEE was only limited by AV calcification. In multivariate regression analysis the mean value of the minimum and maximum AAd obtained in MSCT-multiplanar perpendicular imaging was an

  19. Postmortem imaging: MDCT features of postmortem change and decomposition.

    PubMed

    Levy, Angela D; Harcke, Howard Theodore; Mallak, Craig T

    2010-03-01

    Multidetector computed tomography (MDCT) has emerged as an effective imaging technique to augment forensic autopsy. Postmortem change and decomposition are always present at autopsy and on postmortem MDCT because they begin to occur immediately upon death. Consequently, postmortem change and decomposition on postmortem MDCT should be recognized and not mistaken for a pathologic process or injury. Livor mortis increases the attenuation of vasculature and dependent tissues on MDCT. It may also produce a hematocrit effect with fluid levels in the large caliber blood vessels and cardiac chambers from dependent layering erythrocytes. Rigor mortis and algor mortis have no specific MDCT features. In contrast, decomposition through autolysis, putrefaction, and insect and animal predation produce dramatic alterations in the appearance of the body on MDCT. Autolysis alters the attenuation of organs. The most dramatic autolytic changes on MDCT are seen in the brain where cerebral sulci and ventricles are effaced and gray-white matter differentiation is lost almost immediately after death. Putrefaction produces a pattern of gas that begins with intravascular gas and proceeds to gaseous distension of all anatomic spaces, organs, and soft tissues. Knowledge of the spectrum of postmortem change and decomposition is an important component of postmortem MDCT interpretation.

  20. Characterizing atherosclerotic plaque with computed tomography: a contrast-detail study

    NASA Astrophysics Data System (ADS)

    Kasraie, Nima; Clarke, Geoffrey D.

    2012-02-01

    Plaque characterization may benefit from the increasing distinctiveness of the attenuating properties of different soft plaque components at lower energies. Due to the relative slight increase in the CT number of the nonadipose soft plaque at lower tube voltage settings vs. adipose plaque, a higher contrast between atheromous adipose and non-adipose plaque may become visible with modern 64 slice systems. A contrast-detail (C-D) phantom with varying plaque composition as the contrast generating method, was imaged on a commercial 64 slice MDCT system using 80, 120, and 140 kVp settings. The same phantom was also imaged on a Cone Beam CT (CBCT) system with a lower tube voltage of 75 kVp. The results of experiments from four different observers on three different plaque types (lipid, fiber, calcific) indicate that CT attenuation within lipid cores and fibrous masses vary not only with the percentage of lipid or fiber present, but also with the size of the cores. Furthermore, the C-D curve analysis for all three plaque types reveals that while the noise constraints prevent visible differentiation of soft plaque at current conventional 64 slice MDCT settings, CBCT exhibits superior visible contrast detectability than its conventional counterpart, with the latter having appreciably better resolution limits and beneficial lower tube voltages. This low voltage CT technique has the potential to be useful in composition based diagnosis of carotid vulnerable atherosclerotic plaque.

  1. Spectrum of MDCT Findings in Bowel Obstruction in a Tertiary Care Rural Hospital in Northern India

    PubMed Central

    Gupta, Ranjana; Mittal, Amit; Gupta, Sharad; Mittal, Kapish; Taneja, Arpit

    2016-01-01

    Introduction Multidetector Computed Tomography (MDCT) provides clinically and surgically important information in bowel obstruction. It can depict the severity, level and cause of obstruction. Aim To depict the spectrum of MDCT findings in cases of small and large bowel obstruction. Materials and Methods Contrast enhanced MDCT examination of 50 patients were retrospectively included in the study who had evidence of clinical as well as MDCT evidence of bowel obstruction and in whom surgical/clinical follow-up for final diagnosis was available. CT scan was done in all the patients with Ingenuity CT (128 slice MDCT, Philips Medical Systems). The axial sections were reconstructed in coronal and sagital planes to determine site and cause of bowel obstruction. Results There were 34 males and 16 females patients in this study with mean age of 28.4 years. The level of obstruction was in small bowel in 39 patients (76.67%) and large bowel in 11 patients (23.33%). Adhesive bands were the cause of Small Bowel Obstruction (SBO) in 17 patients (43.5% of SBO patients). The most common CT signs in adhesive band SBO were beak sign (seen in 70.6% patients) and fat notch sign (52.9% patients). Five cases of SBO were secondary to benign stricture. Matted adhesions were the cause of obstruction in 3 patients. All these patients showed transition zone in pelvis with positive small bowel faeces sign. Two patients with SBO due to adhesive band had evidence of closed loop obstruction with evidence of gangrenous gut on surgery. Large Bowel Obstruction (LBO) was seen in 11 patients. Most common cause of LBO was primary colonic malignancy, accounting for 7 patients (63.6%). In one patient, the cause was direct invasion of hepatic flexure by carcinoma of gall bladder. Other causes of LBO were pelvic adhesions, faecal impaction and ischaemic stricture. Conclusion SBO is more common than LBO with adhesive bands being the most common cause of SBO. MDCT is very useful for depicting site and cause

  2. MDCT Versus MRI Assessment of Tumor Response After Transarterial Chemoembolization for the Treatment of Hepatocellular Carcinoma

    SciTech Connect

    Kloeckner, Roman; Otto, Gerd; Biesterfeld, Stefan; Oberholzer, Katja; Dueber, Christoph; Pitton, Michael B.

    2010-06-15

    The purpose of this study was to compare the ability of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) to evaluate treatment results after transarterial chemoembolization (TACE), with a special focus on the influence of Lipiodol on calculation of tumor necrosis according to EASL criteria. A total of 115 nodules in 20 patients (17 males, 3 females; 69.5 {+-} 9.35 years) with biopsy-proven hepatocellular carcinoma were treated with TACE. Embolization was performed using a doxorubicin-Lipiodol emulsion (group I) or DC Beads loaded with doxorubicin (group II). Follow-up included triphasic contrast-enhanced 64-row MDCT (collimation, 0.625 mm; slice, 3 mm; contrast bolus, 120 ml iomeprol; delay by bolus trigger) and contrast-enhanced MRI (T1 native, T2 native; five dynamic contrast-enhanced phases; 0.1 mmol/kg body weight gadolinium-DTPA; slice thickness, 4 mm). Residual tumor and the extent of tumor necrosis were evaluated according to EASL. Contrast enhancement within tumor lesions was suspected to represent vital tumor. In the Lipiodol-based TACE protocol, MDCT underestimated residual viable tumor compared to MRI, due to Lipiodol artifacts (23.2% vs 47.7% after first, 11.9% vs 31.2% after second, and 11.4% vs 23.7% after third TACE; p = 0.0014, p < 0.001, and p < 0.001, respectively). In contrast to MDCT, MRI was completely free of any artifacts caused by Lipiodol. In the DC Bead-based Lipiodol-free TACE protocol, MRI and CT showed similar residual tumor and rating of treatment results (46.4% vs 41.2%, 31.9 vs 26.8%, and 26.0% vs 25.6%; n.s.). In conclusion, MRI is superior to MDCT for detection of viable tumor residuals after Lipiodol-based TACE. Since viable tumor tissue is superimposed by Lipiodol artifacts in MDCT, MRI is mandatory for reliable decision-making during follow-up after Lipiodol-based TACE protocols.

  3. Esophagobronchial fistulae: Diagnosis by MDCT with oral contrast swallow examination of a benign and a malignant cause

    PubMed Central

    Hegde, Rahul G; Kalekar, Tushar M; Gajbhiye, Meenakshi I; Bandgar, Amol S; Pawar, Shephali S; Khadse, Gopal J

    2013-01-01

    We report two cases of esophagobronchial fistulae diagnosed by Multi-detector computed tomography (MDCT) oral contrast swallow examination. It is helpful to supplement the CT study with an oral contrast swallow as it aids in confirmation of a suspected fistula and also demonstrates the fistula tract better. We present the clinical details and the imaging findings on MDCT of two cases of esophagobronchial fistulae – one secondary to chronic chest tuberculosis and the other secondary to a squamous cell carcinoma of the upper esophagus – followed by discussion of the etiology, pathogenesis, and imaging of these fistulae. PMID:24082484

  4. Robust method for extracting the pulmonary vascular trees from 3D MDCT images

    NASA Astrophysics Data System (ADS)

    Taeprasartsit, Pinyo; Higgins, William E.

    2011-03-01

    Segmentation of pulmonary blood vessels from three-dimensional (3D) multi-detector CT (MDCT) images is important for pulmonary applications. This work presents a method for extracting the vascular trees of the pulmonary arteries and veins, applicable to both contrast-enhanced and unenhanced 3D MDCT image data. The method finds 2D elliptical cross-sections and evaluates agreement of these cross-sections in consecutive slices to find likely cross-sections. It next employs morphological multiscale analysis to separate vessels from adjoining airway walls. The method then tracks the center of the likely cross-sections to connect them to the pulmonary vessels in the mediastinum and forms connected vascular trees spanning both lungs. A ground-truth study indicates that the method was able to detect on the order of 98% of the vessel branches having diameter >= 3.0 mm. The extracted vascular trees can be utilized for the guidance of safe bronchoscopic biopsy.

  5. Spontaneous Renal Artery Dissection as a Cause of Acute Renal Infarction: Clinical and MDCT Findings.

    PubMed

    Yoon, Kibo; Song, Soon Young; Lee, Chang Hwa; Ko, Byung Hee; Lee, Seunghun; Kang, Bo Kyeong; Kim, Mi Mi

    2017-04-01

    The purpose of this study was to assess the incidence of spontaneous renal artery dissection (SRAD) as a cause of acute renal infarction, and to evaluate the clinical and multidetector computed tomography (MDCT) findings of SRAD. From November 2011 to January 2014, 35 patients who were diagnosed with acute renal infarction by MDCT were included. We analyzed the 35 MDCT data sets and medical records retrospectively, and compared clinical and imaging features of SRAD with an embolism, using Fisher's exact test and the Mann-Whitney test. The most common cause of acute renal infarction was an embolism, and SRAD was the second most common cause. SRAD patients had new-onset hypertension more frequently than embolic patients. Embolic patients were found to have increased C-reactive protein (CRP) more often than SRAD patients. Laboratory results, including tests for lactate dehydrogenase (LDH) and blood urea nitrogen (BUN), and the BUN/creatinine ratio (BCR) were significantly higher in embolic patients than SRAD patients. Bilateral renal involvement was detected in embolic patients more often than in SRAD patients. MDCT images of SRAD patients showed the stenosis of the true lumen, due to compression by a thrombosed false lumen. None of SRAD patients progressed to an estimated glomerular filtration rate < 60 mL/min/1.73 m² or to end-stage renal disease during the follow-up period. SRAD is not a rare cause of acute renal infarction, and it has a benign clinical course. It should be considered in a differential diagnosis of acute renal infarction, particularly in patients with new-onset hypertension, unilateral renal involvement, and normal ranges of CRP, LDH, BUN, and BCR.

  6. Evaluating the effect of two different anesthetic protocols on 64-MDCT coronary angiography in dogs

    PubMed Central

    Drees, Randi; Johnson, Rebecca A; Pinkerton, Marie; Del Rio, Alejandro Munoz; Saunders, Jimmy H; François, Christopher J

    2014-01-01

    Heart rate is a major factor influencing diagnostic image quality in computed tomographic coronary artery angiography (MDCT-CA) with an ideal heart rate of 60–65 beats/minute in humans. Using standardized contrast bolus volume, two different clinically applicable anesthetic protocols were compared for effect on cardiovascular parameters and 64-MDCT-CA quality in ten healthy dogs. The protocol using midazolam/fentanyl (A) was hypothesized to result in adequate reduction of heart rate achieving adequate image quality for MDCT-CA studies and having low impact on blood pressure, where as the protocol utilizing dexmedetomidine (B) was expected to result in reduction of heart rate to the target heart range resulting in excellent image quality while possibly showing undesirable effect on the blood pressure values measured. Heart rate was 80.6 ± 7.5bpm with protocol A and 79.2 ± 14.2bpm with protocol B during image acquisition (P=1). R-R intervals allowing for the best depiction of the individual coronary artery segments were found in the end diastolic period and varied between the 70–95% interval. Diagnostic quality was rated excellent, good and moderate in the majority of the segments evaluated, with higher scores given for more proximal segments and lower for more distal segments respectively. Blur was the most commonly observed artifact and most affected the distal segments. There was no significant difference for the optimal reconstruction interval, diagnostic quality and measured length individual segments or proximal diameter of the coronary arteries between both protocols (P=1). Both anesthetic protocols and the standardized bolus volume allow for diagnostic quality coronary 64-MDCT-CA exams. PMID:25065815

  7. Spontaneous Renal Artery Dissection as a Cause of Acute Renal Infarction: Clinical and MDCT Findings

    PubMed Central

    2017-01-01

    The purpose of this study was to assess the incidence of spontaneous renal artery dissection (SRAD) as a cause of acute renal infarction, and to evaluate the clinical and multidetector computed tomography (MDCT) findings of SRAD. From November 2011 to January 2014, 35 patients who were diagnosed with acute renal infarction by MDCT were included. We analyzed the 35 MDCT data sets and medical records retrospectively, and compared clinical and imaging features of SRAD with an embolism, using Fisher's exact test and the Mann-Whitney test. The most common cause of acute renal infarction was an embolism, and SRAD was the second most common cause. SRAD patients had new-onset hypertension more frequently than embolic patients. Embolic patients were found to have increased C-reactive protein (CRP) more often than SRAD patients. Laboratory results, including tests for lactate dehydrogenase (LDH) and blood urea nitrogen (BUN), and the BUN/creatinine ratio (BCR) were significantly higher in embolic patients than SRAD patients. Bilateral renal involvement was detected in embolic patients more often than in SRAD patients. MDCT images of SRAD patients showed the stenosis of the true lumen, due to compression by a thrombosed false lumen. None of SRAD patients progressed to an estimated glomerular filtration rate < 60 mL/min/1.73 m2 or to end-stage renal disease during the follow-up period. SRAD is not a rare cause of acute renal infarction, and it has a benign clinical course. It should be considered in a differential diagnosis of acute renal infarction, particularly in patients with new-onset hypertension, unilateral renal involvement, and normal ranges of CRP, LDH, BUN, and BCR. PMID:28244286

  8. Managing patient dose in multi-detector computed tomography(MDCT). ICRP Publication 102.

    PubMed

    Valentin, J

    2007-01-01

    Computed tomography (CT) technology has changed considerably in recent years with the introduction of increasing numbers of multiple detector arrays. There are several parameters specific to multi-detector computed tomography (MDCT) scanners that increase or decrease patient dose systematically compared to older single detector computed tomography (SDCT) scanners. This document briefly reviews the MDCT technology, radiation dose in MDCT, including differences from SDCT and factors that affect dose, radiation risks, and the responsibilities for patient dose management. The document recommends that users need to understand the relationship between patient dose and image quality and be aware that image quality in CT is often higher than that necessary for diagnostic confidence. Automatic exposure control (AEC) does not totally free the operator from selection of scan parameters, and awareness of individual systems is important. Scanning protocols cannot simply be transferred between scanners from different manufacturers and should be determined for each MDCT. If the image quality is appropriately specified by the user, and suited to the clinical task, there will be a reduction in patient dose for most patients. Understanding of some parameters is not intuitive and the selection of image quality parameter values in AEC systems is not straightforward. Examples of some clinical situation shave been included to demonstrate dose management, e.g. CT examinations of the chest, the heart for coronary calcium quantification and non-invasive coronary angiography, colonography, the urinary tract, children, pregnant patients, trauma cases, and CT guided interventions. CT is increasingly being used to replace conventional x-ray studies and it is important that patient dose is given careful consideration, particularly with repeated or multiple examinations.

  9. Spectrum of imaging findings on MDCT enterography in patients with small bowel tuberculosis.

    PubMed

    Kalra, N; Agrawal, P; Mittal, V; Kochhar, R; Gupta, V; Nada, R; Singh, R; Khandelwal, N

    2014-03-01

    Abdominal tuberculosis (TB) is the sixth most common extrapulmonary site of involvement. The sites of involvement in abdominal tuberculosis, in descending order of frequency, are lymph nodes, genitourinary tract, peritoneal cavity, and gastrointestinal tract. The radiological armamentarium for evaluating tuberculosis of the small bowel (SBTB) includes barium studies (small bowel follow-through, SBFT), CT (multidetector CT, CT enterography, and CT enteroclysis), ultrasound (sonoenteroclysis), and magnetic resonance imaging (MRI; enterography and enteroclysis). In this review, we illustrate the abnormalities at MDCT enterography in 20 consecutive patients with SB TB and also describe extraluminal findings in these patients. MDCT enterography allows non-invasive good-quality assessment of well-distended bowel loops and the adjacent soft tissues. It displays the thickness and enhancement of the entire bowel wall in all three planes and allows examination of all bowel loops, especially the ileal loops, which are mostly superimposed. The terminal ileum and ileocaecal junction are the most common sites of small bowel involvement in intestinal TB. The most common abnormality is short-segment strictures with symmetrical concentric mural thickening and homogeneous mural enhancement. Other findings include lymphadenopathy, ascites, enteroliths, peritoneal thickening, and enhancement. In conclusion, MDCT enterography is a comprehensive technique for the evaluation of SB TB.

  10. Quantification of arterial plaque and lumen density with MDCT

    SciTech Connect

    Paul, Narinder S.; Blobel, Joerg; Kashani, Hany; Rice, Murray; Ursani, Ali

    2010-08-15

    Purpose: This study aimed to derive a mathematical correction function in order to normalize the CT number measurements for small volume arterial plaque and small vessel mimicking objects, imaged with multidetector CT (MDCT). Methods: A commercially available calcium plaque phantom (QRM GmbH, Moehrendorf, Germany) and a custom built cardiovascular phantom were scanned with 320 and 64 MDCT scanners. The calcium hydroxyapatite plaque phantom contained objects 0.5-5.0 mm in diameter with known CT attenuation nominal values ranging 50-800 HU. The cardiovascular phantom contained vessel mimicking objects 1.0-5.0 mm in diameter with different contrast media. Both phantoms were scanned using clinical protocols for CT angiography and images were reconstructed with different filter kernels. The measured CT number (HU) and diameter of each object were analyzed on three clinical postprocessing workstations. From the resultant data, a mathematical formula was derived based on absorption function exp(-{mu}{sup *}d) to demonstrate the relation between measured CT numbers and object diameters. Results: The percentage reduction in measured CT number (HU) for the group of selected filter kernels, apparent during CT angiography, is dependent only on the object size (plaque or vessel diameter). The derived formula of the form 1-c{sup *}exp(-a{sup *}d{sup b}) showed reduction in CT number for objects between 0.5 and 5 mm in diameter, with asymptote reaching background noise for small objects with diameters nearing the CT in-plane resolution (0.35 mm). No reduction was observed for the objects with diameters equal or larger than 5 mm. Conclusions: A clear mathematical relationship exists between object diameter and reduction in measured CT number in HU. This function is independent of exposure parameters and inherent attenuation properties of the objects studied. Future developments include the incorporation of this mathematical model function into quantification software in order to

  11. Comparison of hepatic MDCT, MRI, and DSA to explant pathology for the detection and treatment planning of hepatocellular carcinoma

    PubMed Central

    Ladd, Lauren M.; Tirkes, Temel; Tann, Mark; Agarwal, David M.; Johnson, Matthew S.; Tahir, Bilal; Sandrasegaran, Kumaresan

    2016-01-01

    Background/Aims The diagnosis and treatment plan for hepatocellular carcinoma (HCC) can be made from radiologic imaging. However, lesion detection may vary depending on the imaging modality. This study aims to evaluate the sensitivities of hepatic multidetector computed tomography (MDCT), magnetic resonance imaging (MRI), and digital subtraction angiography (DSA) in the detection of HCC and the consequent management impact on potential liver transplant patients. Methods One hundred and sixteen HCC lesions were analyzed in 41 patients who received an orthotopic liver transplant (OLT). All of the patients underwent pretransplantation hepatic DSA, MDCT, and/or MRI. The imaging results were independently reviewed retrospectively in a blinded fashion by two interventional and two abdominal radiologists. The liver explant pathology was used as the gold standard for assessing each imaging modality. Results The sensitivity for overall HCC detection was higher for cross-sectional imaging using MRI (51.5%, 95% confidence interval [CI]=36.2-58.4%) and MDCT (49.8%, 95% CI=43.7-55.9%) than for DSA (41.7%, 95% CI=36.2-47.3%) (P=0.05). The difference in false-positive rate was not statistically significant between MRI (22%), MDCT (29%), and DSA (29%) (P=0.67). The sensitivity was significantly higher for detecting right lobe lesions than left lobe lesions for all modalities (MRI: 56.1% vs. 43.1%, MDCT: 55.0% vs. 42.0%, and DSA: 46.9% vs. 33.9%; all P<0.01). The sensitivities of the three imaging modalities were also higher for lesions ≥2 cm vs. <2 cm (MRI: 73.4% vs. 32.7%, MDCT: 66.9% vs. 33.8%, and DSA: 62.2% vs. 24.1%; all P<0.01). The interobserver correlation was rated as very good to excellent. Conclusion The sensitivity for detecting HCC is higher for MRI and MDCT than for DSA, and so cross-sectional imaging modalities should be used to evaluate OLT candidacy. PMID:27987537

  12. Three-dimensional reconstruction of upper airways from MDCT

    NASA Astrophysics Data System (ADS)

    Perchet, Diane; Fetita, Catalin; Preteux, Francoise

    2005-03-01

    Under the framework of clinical respiratory investigation, providing accurate modalities for morpho-functional analysis is essential for diagnosis improvement, surgical planning and follow-up. This paper focuses on the upper airways investigation and develops an automated approach for 3D mesh reconstruction from MDCT acquisitions. In order to overcome the difficulties related to the complex morphology of the upper airways and to the image gray level heterogeneity of the airway lumens and thin bony septa, the proposed 3D reconstruction methodology combines 2D segmentation and 3D surface regularization approaches. The segmentation algorithm relies on mathematical morphology theory and provides airway lumen robust discrimination from the surrounding tissues, while preserving the connectivity relationship between the different anatomical structures. The 3D regularization step uses an energy-based modeling in order to achieve a smooth and well-fitted 3D surface of the upper airways. An accurate 3D mesh representation of the reconstructed airways makes it possible to develop specific clinical applications such as virtual endoscopy, surgical planning and computer assisted intervention. In addition, building up patient-specific 3D models of upper airways is highly valuable for the study and design of inhaled medication delivery via computational fluid dynamics (CFD) simulations.

  13. Feasibility of Free-breathing CCTA using 256-MDCT.

    PubMed

    Liu, Zhuo; Sun, Ye; Zhang, Zhuolu; Chen, Lei; Hong, Nan

    2016-07-01

    Usually, coronary computed tomography angiography (CCTA) is performed during breath-holding to reduce artifact caused by respiration. The objective of this study was to evaluate the feasibility of free-breathing CCTA compared to breath-holding using CT scanner with wide detector. To evaluate the feasibility of CCTA during free-breathing using a 256-MDCT. In 80 patients who underwent CCTA, 40 were performed during breath-holding (group A), and the remaining 40 during free-breathing (group B). The quality scores for coronary arteries were analyzed and defined as: 3 (excellent), 2 (good), and 1 (poor). The image noise, signal-to-noise ratio and effective radiation dose as well as the heart rate variation were compared. The noise, signal-to-noise ratio, and effective radiation dose were not significantly different between the 2 groups. The mean heart rate variation between planning and scanning for group A was 7 ± 7.6 bpm, and larger than 3 ± 2.6 bpm for group B (P = 0.012). Quality scores of the free-breathing group were better than those of the breath-holding group (group A: 2.55 ± 0.64, group B: 2.85 ± 0.36, P = 0.018). Free-breathing CCTA is feasible on wide detector CT scanner to provide acceptable image quality with reduced heart rate variation and better images for certain patients.

  14. Coronary fly-through or virtual angioscopy using dual-source MDCT data.

    PubMed

    van Ooijen, Peter M A; de Jonge, Gonda; Oudkerk, Matthijs

    2007-11-01

    Coronary fly-through or virtual angioscopy (VA) has been studied ever since its invention in 2000. However, application was limited because it requires an optimal computed tomography (CT) scan and time-consuming post-processing. Recent advances in post-processing software facilitate easy construction of VA, but until now image quality was insufficient in most patients. The introduction of dual-source multidetector CT (MDCT) could enable VA in all patients. Twenty patients were scanned using a dual-source MDCT (Definition, Siemens, Forchheim, Germany) using a standard coronary artery protocol. Post-processing was performed on an Aquarius Workstation (TeraRecon, San Mateo, Calif.). Length travelled per major branch was recorded in millimetres, together with the time required in minutes. VA could be performed in every patient for each of the major coronary arteries. The mean (range) length of the automated fly-through was 80 (32-107) mm for the left anterior descending (LAD), 75 (21-116) mm for the left circumflex artery (LCx), and 109 (21-190) mm for the right coronary artery (RCA). Calcifications and stenoses were visualised, as well as most side branches. The mean time required was 3 min for LAD, 2.5 min for LCx, and 2 min for the RCA. Dual-source MDCT allows for high quality visualisation of the coronary arteries in every patient because scanning with this machine is independent of the heart rate. This is clearly shown by the successful VA in all patients. Potential clinical value of VA should be determined in the near future.

  15. Vascular involvement in periampullary tumors: MDCT, EUS, and CDU.

    PubMed

    Gusmini, S; Nicoletti, R; Martinenghi, C; Del Maschio, A

    2009-07-01

    In patients affected by periampullary tumors, surgical resection represents the only treatment with curative intent. Preoperative evaluation of vascular involvement is necessary to avoid surgical treatments unable of curative intent resection. The aim of our update article is to assess the performance of multidetector computed tomography (MDCT), endoscopic ultrasonography (EUS), and color Doppler ultrasonography (CDU) in the evaluation of vascular involvement of major peripancreatic vessels, in periampullary tumors, analyzing the current and past literature.

  16. Accuracy of Monte Carlo simulations compared to in-vivo MDCT dosimetry

    SciTech Connect

    Bostani, Maryam McMillan, Kyle; Cagnon, Chris H.; McNitt-Gray, Michael F.; Mueller, Jonathon W.; Cody, Dianna D.; DeMarco, John J.

    2015-02-15

    Purpose: The purpose of this study was to assess the accuracy of a Monte Carlo simulation-based method for estimating radiation dose from multidetector computed tomography (MDCT) by comparing simulated doses in ten patients to in-vivo dose measurements. Methods: MD Anderson Cancer Center Institutional Review Board approved the acquisition of in-vivo rectal dose measurements in a pilot study of ten patients undergoing virtual colonoscopy. The dose measurements were obtained by affixing TLD capsules to the inner lumen of rectal catheters. Voxelized patient models were generated from the MDCT images of the ten patients, and the dose to the TLD for all exposures was estimated using Monte Carlo based simulations. The Monte Carlo simulation results were compared to the in-vivo dose measurements to determine accuracy. Results: The calculated mean percent difference between TLD measurements and Monte Carlo simulations was −4.9% with standard deviation of 8.7% and a range of −22.7% to 5.7%. Conclusions: The results of this study demonstrate very good agreement between simulated and measured doses in-vivo. Taken together with previous validation efforts, this work demonstrates that the Monte Carlo simulation methods can provide accurate estimates of radiation dose in patients undergoing CT examinations.

  17. Comparison between a new reconstruction algorithm (OPED) and filtered backprojection (FBP) for MDCT data

    NASA Astrophysics Data System (ADS)

    Renger, Bernhard; No"l, Peter B.; Tischenko, Oleg; Rummeny, Ernst J.; Hoeschen, Christoph

    2012-03-01

    Previously the Orthogonal Polynomial Expansion on the Disk (OPED) algorithm was presented. Further, in prototype experiments in combination with the CT D`or geometry feasibility was demonstrated. In this study we implemented OPED with a clinical Scanner, and evaluated the potential using phantom studies. All studies were acquired on a Siemens Somatom 64 (Erlangen, Germany) scanner, where raw projection data were reconstructed with the conventional FBP reconstruction and the OPED algorithm. OPED allows one to use fan beam geometry directly without any additional procedures such as interpolation or rebinning if using the CT D`or geometry. In particular, OPED describes an approximation of the image function as a sum of polynomials using Chebychev polynomials. For performance evaluation, the Catphan phantom 600 was imaged. OPED Images where reconstructed using C++ and MATLAB® .We measured uniformity, MTF and CNR for different dose levels and compared these to standard FBP images reconstructions with different filter kernels. The integration and interpretation of the MDCT projection data for the OPED algorithm was accomplished. Reconstruction time is about 6 s on Quad-Core 3 GHz Intel Xeon processor. Typical artifacts are reduced when applying OPED. Using OPED the MTF maintains constant over the whole FOV. Uniformity and CNR are equal compared to FBP. Advantages of OPED were demonstrated by applying the algorithm to projections images from a clinical MDCT scanner. In the future, we see OPED applications for low-dose or limited angle geometries to reduce the radiation dose while improving diagnostic quality of the reconstructed slices.

  18. Low fingertip temperature rebound measured by digital thermal monitoring strongly correlates with the presence and extent of coronary artery disease diagnosed by 64-slice multi-detector computed tomography.

    PubMed

    Ahmadi, Naser; Nabavi, Vahid; Nuguri, Vivek; Hajsadeghi, Fereshteh; Flores, Ferdinand; Akhtar, Mohammad; Kleis, Stanley; Hecht, Harvey; Naghavi, Morteza; Budoff, Matthew

    2009-10-01

    Previous studies showed strong correlations between low fingertip temperature rebound measured by digital thermal monitoring (DTM) during a 5 min arm-cuff induced reactive hyperemia and both the Framingham Risk Score (FRS), and coronary artery calcification (CAC) in asymptomatic populations. This study evaluates the correlation between DTM and coronary artery disease (CAD) measured by CT angiography (CTA) in symptomatic patients. It also investigates the correlation between CTA and a new index of neurovascular reactivity measured by DTM. 129 patients, age 63 +/- 9 years, 68% male, underwent DTM, CAC and CTA. Adjusted DTM indices in the occluded arm were calculated: temperature rebound: aTR and area under the temperature curve aTMP-AUC. DTM neurovascular reactivity (NVR) index was measured based on increased fingertip temperature in the non-occluded arm. Obstructive CAD was defined as >or=50% luminal stenosis, and normal as no stenosis and CAC = 0. Baseline fingertip temperature was not different across the groups. However, all DTM indices of vascular and neurovascular reactivity significantly decreased from normal to non-obstructive to obstructive CAD [(aTR 1.77 +/- 1.18 to 1.24 +/- 1.14 to 0.94 +/- 0.92) (P = 0.009), (aTMP-AUC: 355.6 +/- 242.4 to 277.4 +/- 182.4 to 184.4 +/- 171.2) (P = 0.001), (NVR: 161.5 +/- 147.4 to 77.6 +/- 88.2 to 48.8 +/- 63.8) (P = 0.015)]. After adjusting for risk factors, the odds ratio for obstructive CAD compared to normal in the lowest versus two upper tertiles of FRS, aTR, aTMP-AUC, and NVR were 2.41 (1.02-5.93), P = 0.05, 8.67 (2.6-9.4), P = 0.001, 11.62 (5.1-28.7), P = 0.001, and 3.58 (1.09-11.69), P = 0.01, respectively. DTM indices and FRS combined resulted in a ROC curve area of 0.88 for the prediction of obstructive CAD. In patients suspected of CAD, low fingertip temperature rebound measured by DTM significantly predicted CTA-diagnosed obstructive disease.

  19. Visual claudicatio: diagnosis with 64-slice computed tomography.

    PubMed

    Cademartiri, Filippo; Maffei, Erica; Palumbo, Alessandro; Mollet, Nico R; van der Lugt, Aad; Crisi, Girolamo

    2007-06-01

    We present a case of a 78-year-old male referred presented to our institution with amaurosis fugax after walking 20 steps ("visual claudicatio"). Duplex ultrasound was not able to visualize the carotid arteries. Multislice computed tomography (Sensation 64 Cardiac, Siemens, Germany) of the cerebro-vascular circulation was performed from its origin at the level of the aortic arch to the circle of Willis. The investigation demonstrated a complete occlusion of both common carotid arteries at their origin and a severe origo stenosis of both vertebral arteries. An important collateral circulation of the vertebral arteries through the minor vessels of the neck was also displayed. Both comunicans posterior arteries were small but patent. The intra-cranial arteries were patent. Multislice CT of the cerebro-vascular circulation is an optimal tool for a comprehensive evaluation when duplex ultrasound fails.

  20. MDCT imaging of the stomach: advances and applications.

    PubMed

    Nagpal, Prashant; Prakash, Anjali; Pradhan, Gaurav; Vidholia, Aditi; Nagpal, Nishant; Saboo, Sachin S; Kuehn, David M; Khandelwal, Ashish

    2017-01-01

    The stomach may be involved by a myriad of pathologies ranging from benign aetiologies like inflammation to malignant aetiologies like carcinoma or lymphoma. Multidetector CT (MDCT) of the stomach is the first-line imaging for patients with suspected gastric pathologies. Conventionally, CT imaging had the advantage of simultaneous detection of the mural and extramural disease extent, but advances in MDCT have allowed mucosal assessment by virtual endoscopy (VE). Also, better three-dimensional (3D) post-processing techniques have enabled more robust and accurate pre-operative planning in patients undergoing gastrectomy and even predict the response to surgery for patients undergoing laparoscopic sleeve gastrectomy for weight loss. The ability of CT to obtain stomach volume (for bariatric surgery patients) and 3D VE images depends on various patient and protocol factors that are important for a radiologist to understand. We review the appropriate CT imaging protocol in the patients with suspected gastric pathologies and highlight the imaging pearls of various gastric pathologies on CT and VE.

  1. MDCT of hand and wrist infections: emphasis on compartmental anatomy.

    PubMed

    Ahlawat, S; Corl, F M; LaPorte, D M; Fishman, E K; Fayad, L M

    2017-04-01

    Hand and wrist infections can present with a spectrum of manifestations ranging from cellulitis to deep-space collections. The various infectious processes can be categorised as superficial or deep infections based on their respective locations relative to the tendons. Superficial hand infections are located superficial to the tendons and are comprised of cellulitis, lymphangitis, paronychia, pulp-space infections, herpetic whitlow, and include volar as well as dorsal subcutaneous abscesses. Deep hand infections are located deep to the tendon sheaths and include synovial space infections, such as infectious tenosynovitis, deep fascial space infections, septic arthritis, necrotising fasciitis, and osteomyelitis. Knowledge of hand and wrist compartmental anatomy is essential for the accurate diagnosis and management of hand infections. Although early and superficial infections of the hand may respond to non-surgical management, most hand infections are surgical emergencies. Multidetector computed tomography (MDCT), with its muliplanar reformation (MPR) and three-dimensional (3D) capabilities, is a powerful tool in the emergency setting for the evaluation of acute hand and wrist pathology. The clinical and imaging features of hand and wrist infections as evident on MDCT will be reviewed with emphasis on contiguous and closed synovial and deep fascial spaces. Knowledge of hand compartmental anatomy enables accurate characterisation of the infectious process and localise the extent of disease in the acute setting.

  2. MDCT evaluation of sternal variations: Pictorial essay

    PubMed Central

    Duraikannu, Chary; Noronha, Olma V; Sundarrajan, Pushparajan

    2016-01-01

    Sternal variations and anomalies have been identified in the past during autopsy or cadaveric studies. Recently, an increasing number of minor sternal variations have been reported with the advent of multidetector computed tomography (CT). Although there are many sternal variations that occur with varying appearance and prevalence, most of them are not recognized or are underreported during routine imaging of thorax. Identification of sternal variations is important to differentiate from pathological conditions and to prevent fatal complications prior to sternal interventions like marrow aspiration or acupuncture. This article aims to describe the minor and asymptomatic sternal variations by multidetector CT and their clinical significance. PMID:27413263

  3. Mixed-radix Algorithm for the Computation of Forward and Inverse MDCT

    PubMed Central

    Wu, Jiasong; Shu, Huazhong; Senhadji, Lotfi; Luo, Limin

    2008-01-01

    The modified discrete cosine transform (MDCT) and inverse MDCT (IMDCT) are two of the most computational intensive operations in MPEG audio coding standards. A new mixed-radix algorithm for efficient computing the MDCT/IMDCT is presented. The proposed mixed-radix MDCT algorithm is composed of two recursive algorithms. The first algorithm, called the radix-2 decimation in frequency (DIF) algorithm, is obtained by decomposing an N-point MDCT into two MDCTs with the length N/2. The second algorithm, called the radix-3 decimation in time (DIT) algorithm, is obtained by decomposing an N-point MDCT into three MDCTs with the length N/3. Since the proposed MDCT algorithm is also expressed in the form of a simple sparse matrix factorization, the corresponding IMDCT algorithm can be easily derived by simply transposing the matrix factorization. Comparison of the proposed algorithm with some existing ones shows that our proposed algorithm is more suitable for parallel implementation and especially suitable for the layer III of MPEG-1 and MPEG-2 audio encoding and decoding. Moreover, the proposed algorithm can be easily extended to the multidimensional case by using the vector-radix method. PMID:21258639

  4. A Rare Presentation of an Entrapment in a Liver Transplant Candidate Depicted by MDCT Angiography

    PubMed Central

    Kantarci, Mecit; Aydin, Unal; Doganay, Selim; Aydinli, Bulent; Yuce, Ihsan; Polat, Kamil Yalcin

    2010-01-01

    Hypertrophic caudate lobe veins can mimic a normal venous configuration. In cases of multiple vascular collaterals, Doppler evaluations must be conducted, and the flow direction of these veins as well as the IVC should be evaluated. If the flow in the IVC is reversed, Budd-Chiari syndrome should be suspected; moreover, at the supra diaphragmatic level, which may be considered a blind spot, particularly for radiologists, a web should be searched for in the area where the IVC opens into the right atrium. In this study, we present the unique findings of multidetector computed tomography (MDCT) angiography for a liver transplant candidate with Budd-Chiari syndrome caused by a web in the proximal IVC. PMID:25610132

  5. Diagnostic Value and Interreader Agreement of the Pancreaticolienal Gap in Pancreatic Cancer on MDCT

    PubMed Central

    Schawkat, Khoschy; Kühn, Wolfgang; Inderbitzin, Daniel; Gloor, Beat; Heverhagen, Johannes T.; Runge, Val Murray; Christe, Andreas

    2016-01-01

    Objective The aim of this retrospective study was to evaluate the diagnostic value and measure interreader agreement of the pancreaticolienal gap (PLG) in the assessment of imaging features of pancreatic carcinoma (PC) on contrast-enhanced multi-detector computed tomography (CE-MDCT). Materials and Methods CE-MDCT studies in the portal venous phase were retrospectively reviewed for 66 patients with PC. The age- and gender-matched control group comprised 103 healthy individuals. Three radiologists with different levels of experience independently measured the PLG (the minimum distance of the pancreatic tail to the nearest border of the spleen) in the axial plane. The interreader agreement of the PLG and the receiver operating characteristic (ROC) curve was used to calculate the accuracy of the technique. Results While the control group (n = 103) showed a median PLG of 3 mm (Range: 0 – 39mm) the PC patients had a significantly larger PLG of 15mm (Range: 0 – 53mm)(p < 0.0001). A ROC curve demonstrated a cutoff-value of >12 mm for PC, with a sensitivity of 58.2% (95% CI = 45.5–70.1), specificity of 84.0% (95% CI = 75.6–90.4) and an area under the ROC curve of 0.714 (95% CI = 0.641 to 0.780). The mean interreader agreement showed correlation coefficient r of 0.9159. The extent of the PLG did not correlate with tumor stage but did correlate with pancreatic density (fatty involution) and age, the density decreased by 4.1 HU and the PLG increased by 0.8 mm within every 10 y. Conclusion The significant interreader agreement supports the use of the PLG as a characterizing feature of pancreatic cancer independent of the tumor stage on an axial plane. The increase in the PLG with age may represent physiological atrophy of the pancreatic tail. PMID:27893776

  6. Polyarteritis nodosa: MDCT as a 'One-Stop Shop' Modality for Whole-Body Arterial Evaluation

    SciTech Connect

    Tsai, W.-L.; Tsai, I-C.; Lee Tain; Hsieh, C.-W.

    2008-07-15

    Polyarteritis nodosa is a rare disease, which is characterized by aneurysm formation and occlusion in the arteries of multiple systems. Due to its extensive involvement, whole-body evaluation is necessary for diagnosis and treatment monitoring. We report a case of polyarteritis nodosa using multidetector-row computed tomography (MDCT) as a 'one-stop shop' modality for whole-body arterial evaluation. With precise protocol design, MDCT can be used as a reliable noninvasive modality providing comprehensive whole-body arterial evaluation.

  7. The impacts of open-mouth breathing on upper airway space in obstructive sleep apnea: 3-D MDCT analysis.

    PubMed

    Kim, Eun Joong; Choi, Ji Ho; Kim, Kang Woo; Kim, Tae Hoon; Lee, Sang Hag; Lee, Heung Man; Shin, Chol; Lee, Ki Yeol; Lee, Seung Hoon

    2011-04-01

    Open-mouth breathing during sleep is a risk factor for obstructive sleep apnea (OSA) and is associated with increased disease severity and upper airway collapsibility. The aim of this study was to investigate the effect of open-mouth breathing on the upper airway space in patients with OSA using three-dimensional multi-detector computed tomography (3-D MDCT). The study design included a case-control study with planned data collection. The study was performed at a tertiary medical center. 3-D MDCT analysis was conducted on 52 patients with OSA under two experimental conditions: mouth closed and mouth open. Under these conditions, we measured the minimal cross-sectional area of the retropalatal and retroglossal regions (mXSA-RP, mXSA-RG), as well as the upper airway length (UAL), defined as the vertical dimension from hard palate to hyoid. We also computed the volume of the upper airway space by 3-D reconstruction of both conditions. When the mouth was open, mXSA-RP and mXSA-RG significantly decreased and the UAL significantly increased, irrespective of the severity of OSA. However, between the closed- and open-mouth states, there was no significant change in upper airway volume at any severity of OSA. Results suggest that the more elongated and narrow upper airway during open-mouth breathing may aggravate the collapsibility of the upper airway and, thus, negatively affect OSA severity.

  8. Accurate 3D quantification of the bronchial parameters in MDCT

    NASA Astrophysics Data System (ADS)

    Saragaglia, A.; Fetita, C.; Preteux, F.; Brillet, P. Y.; Grenier, P. A.

    2005-08-01

    The assessment of bronchial reactivity and wall remodeling in asthma plays a crucial role in better understanding such a disease and evaluating therapeutic responses. Today, multi-detector computed tomography (MDCT) makes it possible to perform an accurate estimation of bronchial parameters (lumen and wall areas) by allowing a quantitative analysis in a cross-section plane orthogonal to the bronchus axis. This paper provides the tools for such an analysis by developing a 3D investigation method which relies on 3D reconstruction of bronchial lumen and central axis computation. Cross-section images at bronchial locations interactively selected along the central axis are generated at appropriate spatial resolution. An automated approach is then developed for accurately segmenting the inner and outer bronchi contours on the cross-section images. It combines mathematical morphology operators, such as "connection cost", and energy-controlled propagation in order to overcome the difficulties raised by vessel adjacencies and wall irregularities. The segmentation accuracy was validated with respect to a 3D mathematically-modeled phantom of a pair bronchus-vessel which mimics the characteristics of real data in terms of gray-level distribution, caliber and orientation. When applying the developed quantification approach to such a model with calibers ranging from 3 to 10 mm diameter, the lumen area relative errors varied from 3.7% to 0.15%, while the bronchus area was estimated with a relative error less than 5.1%.

  9. Shading correction for on-board cone-beam CT in radiation therapy using planning MDCT images

    SciTech Connect

    Niu Tianye; Sun, Mingshan; Star-Lack, Josh; Gao Hewei; Fan Qiyong; Zhu Lei

    2010-10-15

    Purpose: Applications of cone-beam CT (CBCT) to image-guided radiation therapy (IGRT) are hampered by shading artifacts in the reconstructed images. These artifacts are mainly due to scatter contamination in the projections but also can result from uncorrected beam hardening effects as well as nonlinearities in responses of the amorphous silicon flat panel detectors. While currently, CBCT is mainly used to provide patient geometry information for treatment setup, more demanding applications requiring high-quality CBCT images are under investigation. To tackle these challenges, many CBCT correction algorithms have been proposed; yet, a standard approach still remains unclear. In this work, we propose a shading correction method for CBCT that addresses artifacts from low-frequency projection errors. The method is consistent with the current workflow of radiation therapy. Methods: With much smaller inherent scatter signals and more accurate detectors, diagnostic multidetector CT (MDCT) provides high quality CT images that are routinely used for radiation treatment planning. Using the MDCT image as ''free'' prior information, we first estimate the primary projections in the CBCT scan via forward projection of the spatially registered MDCT data. Since most of the CBCT shading artifacts stem from low-frequency errors in the projections such as scatter, these errors can be accurately estimated by low-pass filtering the difference between the estimated and raw CBCT projections. The error estimates are then subtracted from the raw CBCT projections. Our method is distinct from other published correction methods that use the MDCT image as a prior because it is projection-based and uses limited patient anatomical information from the MDCT image. The merit of CBCT-based treatment monitoring is therefore retained. Results: The proposed method is evaluated using two phantom studies on tabletop systems. On the Catphan(c)600 phantom, our approach reduces the reconstruction error

  10. Three-dimensional MDCT angiography of splanchnic arteries: pearls and pitfalls.

    PubMed

    Dohan, A; Dautry, R; Guerrache, Y; Fargeaudou, Y; Boudiaf, M; Le Dref, O; Sirol, M; Soyer, P

    2015-02-01

    Fast scanning along with high resolution of multidetector computed tomography (MDCT) have expanded the role of non-invasive imaging of splanchnic arteries. Advancements in both MDCT scanner technology and three-dimensional (3D) imaging software provide a unique opportunity for non-invasive investigation of splanchnic arteries. Although standard axial computed tomography (CT) images allow identification of splanchnic arteries, visualization of small or distal branches is often limited. Similarly, a comprehensive assessment of the complex anatomy of splanchnic arteries is often beyond the reach of axial images. However, the submillimeter collimation that can be achieved with MDCT scanners now allows the acquisition of true isotropic data so that a high spatial resolution is now maintained in any imaging plane and in 3D mode. This ability to visualize the complex network of splanchnic arteries using 3D rendering and multiplanar reconstruction is of major importance for an optimal analysis in many situations. The purpose of this review is to discuss and illustrate the role of 3D MDCT angiography in the detection and assessment of abnormalities of splanchnic arteries as well as the limitations of the different reconstruction techniques.

  11. US and MDCT diagnosis of a rare cause of haematuria in children: Posterior nutcracker syndrome.

    PubMed

    Ozel, A; Tufaner, O; Kaya, E; Maldur, V

    2011-06-01

    Posterior nutcracker syndrome is caused by compression of the left renal vein between the abdominal aorta and the vertebral column. We present the case of a 14-year-old girl with vague left loin pain, mild haematuria and proteinuria. Diagnosis of this rare syndrome was achieved using color Doppler US and multidetector computed tomography (MDCT) angiography.

  12. Semi-automatic central-chest lymph-node definition from 3D MDCT images

    NASA Astrophysics Data System (ADS)

    Lu, Kongkuo; Higgins, William E.

    2010-03-01

    Central-chest lymph nodes play a vital role in lung-cancer staging. The three-dimensional (3D) definition of lymph nodes from multidetector computed-tomography (MDCT) images, however, remains an open problem. This is because of the limitations in the MDCT imaging of soft-tissue structures and the complicated phenomena that influence the appearance of a lymph node in an MDCT image. In the past, we have made significant efforts toward developing (1) live-wire-based segmentation methods for defining 2D and 3D chest structures and (2) a computer-based system for automatic definition and interactive visualization of the Mountain central-chest lymph-node stations. Based on these works, we propose new single-click and single-section live-wire methods for segmenting central-chest lymph nodes. The single-click live wire only requires the user to select an object pixel on one 2D MDCT section and is designed for typical lymph nodes. The single-section live wire requires the user to process one selected 2D section using standard 2D live wire, but it is more robust. We applied these methods to the segmentation of 20 lymph nodes from two human MDCT chest scans (10 per scan) drawn from our ground-truth database. The single-click live wire segmented 75% of the selected nodes successfully and reproducibly, while the success rate for the single-section live wire was 85%. We are able to segment the remaining nodes, using our previously derived (but more interaction intense) 2D live-wire method incorporated in our lymph-node analysis system. Both proposed methods are reliable and applicable to a wide range of pulmonary lymph nodes.

  13. Effects of computing parameters and measurement locations on the estimation of 3D NPS in non-stationary MDCT images.

    PubMed

    Miéville, Frédéric A; Bolard, Gregory; Bulling, Shelley; Gudinchet, François; Bochud, François O; Verdun, François R

    2013-11-01

    The goal of this study was to investigate the impact of computing parameters and the location of volumes of interest (VOI) on the calculation of 3D noise power spectrum (NPS) in order to determine an optimal set of computing parameters and propose a robust method for evaluating the noise properties of imaging systems. Noise stationarity in noise volumes acquired with a water phantom on a 128-MDCT and a 320-MDCT scanner were analyzed in the spatial domain in order to define locally stationary VOIs. The influence of the computing parameters in the 3D NPS measurement: the sampling distances bx,y,z and the VOI lengths Lx,y,z, the number of VOIs NVOI and the structured noise were investigated to minimize measurement errors. The effect of the VOI locations on the NPS was also investigated. Results showed that the noise (standard deviation) varies more in the r-direction (phantom radius) than z-direction plane. A 25 × 25 × 40 mm(3) VOI associated with DFOV = 200 mm (Lx,y,z = 64, bx,y = 0.391 mm with 512 × 512 matrix) and a first-order detrending method to reduce structured noise led to an accurate NPS estimation. NPS estimated from off centered small VOIs had a directional dependency contrary to NPS obtained from large VOIs located in the center of the volume or from small VOIs located on a concentric circle. This showed that the VOI size and location play a major role in the determination of NPS when images are not stationary. This study emphasizes the need for consistent measurement methods to assess and compare image quality in CT.

  14. Ectopia cordis with tetralogy of Fallot in an infant with pentalogy of Cantrell: high-pitch MDCT exam.

    PubMed

    Santiago-Herrera, Rogerio; Ramirez-Carmona, Rocio; Criales-Vera, Sergio; Calderon-Colmenero, Juan; Kimura-Hayama, Eric

    2011-07-01

    We report the MDCT findings of a 17-month-old girl with Cantrell's pentalogy, a rare congenital disease characterized by several defects in the ventral thoracoabdominal wall including ectopia cordis, and, in this patient, associated with tetralogy of Fallot. This case provides an example of the utility of a wide volume in coverage and high-pitch MDCT scan in the evaluation of complex cardiovascular anatomy in infants with congenital heart disease without the need of an ECG-gating acquisition.

  15. Congenital thoracic vascular anomalies: evaluation with state-of-the-art MR imaging and MDCT.

    PubMed

    Hellinger, Jeffrey C; Daubert, Melissa; Lee, Edward Y; Epelman, Monica

    2011-09-01

    Congenital thoracic vascular anomalies include embryologic developmental disorders of the thoracic aorta, aortic arch branch arteries, pulmonary arteries, thoracic systemic veins, and pulmonary veins. Diagnostic evaluation of these anomalies in pediatric patients has evolved with innovations in diagnostic imaging technology. State-of-the-art magnetic resonance (MR) imaging, MR angiography multidetector-row computed tomographic (MDCT) angiography, and advanced postprocessing visualization techniques offer accurate and reliable high-resolution two-dimensional and three-dimensional noninvasive anatomic displays for interpretation and clinical management of congenital thoracic vascular anomalies. This article reviews vascular MR imaging, MR angiography, MDCT angiography, and advanced visualization techniques and applications for the assessment of congenital thoracic vascular anomalies, emphasizing clinical embryology and the characteristic imaging findings.

  16. State-of-the-art preoperative staging of gastric cancer by MDCT and magnetic resonance imaging

    PubMed Central

    Choi, Joon-Il; Joo, Ijin; Lee, Jeong Min

    2014-01-01

    Gastric cancer is one of the most common and fatal cancers. The importance of accurate staging for gastric cancer has become more critical due to the recent introduction of less invasive treatment options, such as endoscopic mucosal resection or laparoscopic surgery. The tumor-node-metastasis staging system is the generally accepted staging system for predicting the prognosis of patients with gastric cancer. Multidetector row computed tomography (MDCT) is a widely accepted imaging modality for the preoperative staging of gastric cancer that can simultaneously assess locoregional staging, including the gastric mass, regional lymph nodes, and distant metastasis. The diagnostic performance of MDCT for T- and N-staging has been improved by the technical development of isotropic imaging and 3D reformation. Although magnetic resonance imaging (MRI) was not previously used to evaluate gastric cancer due to the modality’s limitations, the development of high-speed sequences has made MRI a feasible tool for the staging of gastric cancer. PMID:24782607

  17. MDCT Imaging Findings of Liver Cirrhosis: Spectrum of Hepatic and Extrahepatic Abdominal Complications

    PubMed Central

    Sangster, Guillermo P.; Previgliano, Carlos H.; Nader, Mathieu; Chwoschtschinsky, Elisa; Heldmann, Maureen G.

    2013-01-01

    Hepatic cirrhosis is the clinical and pathologic result of a multifactorial chronic liver injury. It is well known that cirrhosis is the origin of multiple extrahepatic abdominal complications and a markedly increased risk of hepatocellular carcinoma (HCC). This tumor is the sixth most common malignancy worldwide and the third most common cause of cancer related death. With the rising incidence of HCC worldwide, awareness of the evolution of cirrhotic nodules into malignancy is critical for an early detection and treatment. Adequate imaging protocol selection with dynamic multiphase Multidetector Computed Tomography (MDCT) and reformatted images is crucial to differentiate and categorize the hepatic nodular dysplasia. Knowledge of the typical and less common extrahepatic abdominal manifestations is essential for accurately assessing patients with known or suspected hepatic disease. The objective of this paper is to illustrate the imaging spectrum of intra- and extrahepatic abdominal manifestations of hepatic cirrhosis seen on MDCT. PMID:23986608

  18. Monte Carlo simulations in multi-detector CT (MDCT) for two PET/CT scanner models using MASH and FASH adult phantoms

    NASA Astrophysics Data System (ADS)

    Belinato, W.; Santos, W. S.; Paschoal, C. M. M.; Souza, D. N.

    2015-06-01

    The combination of positron emission tomography (PET) and computed tomography (CT) has been extensively used in oncology for diagnosis and staging of tumors, radiotherapy planning and follow-up of patients with cancer, as well as in cardiology and neurology. This study determines by the Monte Carlo method the internal organ dose deposition for computational phantoms created by multidetector CT (MDCT) beams of two PET/CT devices operating with different parameters. The different MDCT beam parameters were largely related to the total filtration that provides a beam energetic change inside the gantry. This parameter was determined experimentally with the Accu-Gold Radcal measurement system. The experimental values of the total filtration were included in the simulations of two MCNPX code scenarios. The absorbed organ doses obtained in MASH and FASH phantoms indicate that bowtie filter geometry and the energy of the X-ray beam have significant influence on the results, although this influence can be compensated by adjusting other variables such as the tube current-time product (mAs) and pitch during PET/CT procedures.

  19. Systems for Lung Volume Standardization during Static and Dynamic MDCT-based Quantitative Assessment of Pulmonary Structure and Function

    PubMed Central

    Fuld, Matthew K.; Grout, Randall; Guo, Junfeng; Morgan, John H.; Hoffman, Eric A.

    2013-01-01

    Rationale and Objectives Multidetector-row Computed Tomography (MDCT) has emerged as a tool for quantitative assessment of parenchymal destruction, air trapping (density metrics) and airway remodeling (metrics relating airway wall and lumen geometry) in chronic obstructive pulmonary disease (COPD) and asthma. Critical to the accuracy and interpretability of these MDCT-derived metrics is the assurance that the lungs are scanned during a breath-hold at a standardized volume. Materials and Methods A computer monitored turbine-based flow meter system was developed to control patient breath-holds and facilitate static imaging at fixed percentages of the vital capacity. Due to calibration challenges with gas density changes during multi-breath xenon-CT an alternative system was required. The design incorporated dual rolling seal pistons. Both systems were tested in a laboratory environment and human subject trials. Results The turbine-based system successfully controlled lung volumes in 32/37 subjects, having a linear relationship for CT measured air volume between repeated scans: for all scans, the mean and confidence interval of the differences (scan1-scan2) was −9 ml (−169, 151); for TLC alone 6 ml (−164, 177); for FRC alone, −23 ml (−172, 126). The dual-piston system successfully controlled lung volume in 31/41 subjects. Study failures related largely to subject non-compliance with verbal instruction and gas leaks around the mouthpiece. Conclusion We demonstrate the successful use of a turbine-based system for static lung volume control and demonstrate its inadequacies for dynamic xenon-CT studies. Implementation of a dual-rolling seal spirometer has been shown to adequately control lung volume for multi-breath wash-in xenon-CT studies. These systems coupled with proper patient coaching provide the tools for the use of CT to quantitate regional lung structure and function. The wash-in xenon-CT method for assessing regional lung function, while not

  20. National Survey of Radiation Dose and Image Quality in Adult CT Head Scans in Taiwan

    PubMed Central

    Lin, Chung-Jung; Mok, Greta S. P.; Tsai, Mang-Fen; Tsai, Wei-Ta; Yang, Bang-Hung; Tu, Chun-Yuan; Wu, Tung-Hsin

    2015-01-01

    Introduction The purpose of the present study was to evaluate the influence of different variables on radiation dose and image quality based on a national database. Materials and Methods Taiwan’s Ministry of Health and Welfare requested all radiology departments to complete a questionnaire for each of their CT scanners. Information gathered included all scanning parameters for CT head scans. For the present analysis, CT machines were divided into three subgroups: single slice CT (Group A); multi-detector CT (MDCT) with 2-64 slices (Group B); and MDCT with more than 64 slices (Group C). Correlations between computed tomography dose index (CTDI) and signal-to-noise ratio (SNR) with cumulated tube rotation number (CTW(n)) and cumulated tube rotation time (CTW(s)), and sub group analyses of CTDI and SNR across the three groups were performed. Results CTDI values demonstrated a weak correlation (r = 0.33) with CTW(n) in Group A. SNR values demonstrated a weak negative correlation (r = -0.46) with CTW(n) in Group C. MDCT with higher slice numbers used more tube potential resulting in higher effective doses. There were both significantly lower CTDI and SNR values in helical mode than in axial mode in Group B, but not Group C. Conclusion CTW(n) and CTW(s) did not influence radiation output. Helical mode is more often used in MDCT and results in both lower CTDI and SNR compared to axial mode in MDCT with less than 64 slices. PMID:26125549

  1. Ileocaecal Intussusception with a Lead Point: Unusual MDCT Findings of Active Crohn's Disease Involving the Appendix

    PubMed Central

    Ozan, Ebru; Atac, Gokce Kaan; Akincioglu, Egemen; Keskin, Mete; Gulpinar, Kamil

    2015-01-01

    Adult intussusception is a rare entity accounting for 1% of all bowel obstructions. Unlike intussusceptions in children, which are idiopathic in 90% of cases, adult intussusceptions have an identifiable cause (lead point) in the majority of cases. Crohn's disease (CD) may affect any part of the gastrointestinal tract, including the appendix. It was shown to be a predisposing factor for intussusception. Here, we report a rare case of adult intussusception with a lead point, emphasizing diagnostic input of multidetector computed tomography (MDCT) in a patient with active CD that involves the appendix. PMID:26558130

  2. Effect of Low-Dose MDCT and Iterative Reconstruction on Trabecular Bone Microstructure Assessment

    PubMed Central

    Baum, Thomas; Nasirudin, Radin A.; Mei, Kai; Garcia, Eduardo G.; Burgkart, Rainer; Rummeny, Ernst J.; Kirschke, Jan S.; Noël, Peter B.

    2016-01-01

    We investigated the effects of low-dose multi detector computed tomography (MDCT) in combination with statistical iterative reconstruction algorithms on trabecular bone microstructure parameters. Twelve donated vertebrae were scanned with the routine radiation exposure used in our department (standard-dose) and a low-dose protocol. Reconstructions were performed with filtered backprojection (FBP) and maximum-likelihood based statistical iterative reconstruction (SIR). Trabecular bone microstructure parameters were assessed and statistically compared for each reconstruction. Moreover, fracture loads of the vertebrae were biomechanically determined and correlated to the assessed microstructure parameters. Trabecular bone microstructure parameters based on low-dose MDCT and SIR significantly correlated with vertebral bone strength. There was no significant difference between microstructure parameters calculated on low-dose SIR and standard-dose FBP images. However, the results revealed a strong dependency on the regularization strength applied during SIR. It was observed that stronger regularization might corrupt the microstructure analysis, because the trabecular structure is a very small detail that might get lost during the regularization process. As a consequence, the introduction of SIR for trabecular bone microstructure analysis requires a specific optimization of the regularization parameters. Moreover, in comparison to other approaches, superior noise-resolution trade-offs can be found with the proposed methods. PMID:27447827

  3. MDCT evaluation of potential living renal donor, prior to laparoscopic donor nephrectomy: What the transplant surgeon wants to know?

    PubMed

    Ghonge, Nitin P; Gadanayak, Satyabrat; Rajakumari, Vijaya

    2014-10-01

    As Laparoscopic Donor Nephrectomy (LDN) offers several advantages for the donor such as lesser post-operative pain, fewer cosmetic concerns and faster recovery time, there is growing global trend towards LDN as compared to open nephrectomy. Comprehensive pre-LDN donor evaluation includes assessment of renal morphology including pelvi-calyceal and vascular system. Apart from donor selection, evaluation of the regional anatomy allows precise surgical planning. Due to limited visualization during laparoscopic renal harvesting, detailed pre-transplant evaluation of regional anatomy, including the renal venous anatomy is of utmost importance. MDCT is the modality of choice for pre-LDN evaluation of potential renal donors. Apart from appropriate scan protocol and post-processing methods, detailed understanding of surgical techniques is essential for the Radiologist for accurate image interpretation during pre-LDN MDCT evaluation of potential renal donors. This review article describes MDCT evaluation of potential living renal donor, prior to LDN with emphasis on scan protocol, post-processing methods and image interpretation. The article laid special emphasis on surgical perspectives of pre-LDN MDCT evaluation and addresses important points which transplant surgeons want to know.

  4. Hepatic Arterial Configuration in Relation to the Segmental Anatomy of the Liver; Observations on MDCT and DSA Relevant to Radioembolization Treatment

    SciTech Connect

    Hoven, Andor F. van den Leeuwen, Maarten S. van Lam, Marnix G. E. H. Bosch, Maurice A. A. J. van den

    2015-02-15

    PurposeCurrent anatomical classifications do not include all variants relevant for radioembolization (RE). The purpose of this study was to assess the individual hepatic arterial configuration and segmental vascularization pattern and to develop an individualized RE treatment strategy based on an extended classification.MethodsThe hepatic vascular anatomy was assessed on MDCT and DSA in patients who received a workup for RE between February 2009 and November 2012. Reconstructed MDCT studies were assessed to determine the hepatic arterial configuration (origin of every hepatic arterial branch, branching pattern and anatomical course) and the hepatic segmental vascularization territory of all branches. Aberrant hepatic arteries were defined as hepatic arterial branches that did not originate from the celiac axis/CHA/PHA. Early branching patterns were defined as hepatic arterial branches originating from the celiac axis/CHA.ResultsThe hepatic arterial configuration and segmental vascularization pattern could be assessed in 110 of 133 patients. In 59 patients (54 %), no aberrant hepatic arteries or early branching was observed. Fourteen patients without aberrant hepatic arteries (13 %) had an early branching pattern. In the 37 patients (34 %) with aberrant hepatic arteries, five also had an early branching pattern. Sixteen different hepatic arterial segmental vascularization patterns were identified and described, differing by the presence of aberrant hepatic arteries, their respective vascular territory, and origin of the artery vascularizing segment four.ConclusionsThe hepatic arterial configuration and segmental vascularization pattern show marked individual variability beyond well-known classifications of anatomical variants. We developed an individualized RE treatment strategy based on an extended anatomical classification.

  5. Whole-Chest 64-MDCT of Emergency Department Patients with Nonspecific Chest Pain: Radiation Dose and Coronary Artery Image Quality with Prospective ECG Triggering Versus Retrospective ECG Gating

    PubMed Central

    Shuman, William P.; Branch, Kelley R.; May, Janet M.; Mitsumori, Lee M.; Strote, Jared N.; Warren, Bill H.; Dubinsky, Theodore J.; Lockhart, David W.; Caldwell, James H.

    2012-01-01

    Objective The purpose of this study was to compare the patient radiation dose and coronary artery image quality of long-z-axis whole-chest 64-MDCT performed with retrospective ECG gating with those of CT performed with prospective ECG triggering in the evaluation of emergency department patients with nonspecific chest pain. Subjects and Methods Consecutively registered emergency department patients with nonspecific low-to-moderate-risk chest pain underwent whole-chest CT with retrospective gating (n = 41) or prospective triggering (n = 31). Effective patient radiation doses were estimated and compared by use of unpaired Student's t tests. Two reviewers independently scored the quality of images of the coronary arteries, and the scores were compared by use of ordinal logistic regression. Results Age, heart rate, body mass index, and z-axis coverage were not statistically different between the two groups. For retrospective gating, the mean effective radiation dose was 31.8 ± 5.1 mSv; for prospective triggering, the mean effective radiation dose was 9.2 ± 2.2 mSv (prospective triggering 71% lower, p < 0.001). Two of 512 segments imaged with retrospective gating were nonevaluable (0.4%), and two of 394 segments imaged with prospective triggering were nonevaluable (0.5%). Prospectively triggered images were 2.2 (95% CI, 1.1–4.5) times as likely as retrospectively gated images to receive a high image quality score for each segment after adjustment for segment differences (p < 0.05). Conclusion For long-z-axis whole-chest 64-MDCT of emergency department patients with nonspecific chest pain, use of prospective ECG triggering may result in substantially lower patient radiation doses and better coronary artery image quality than is achieved with retrospective ECG gating. PMID:19457832

  6. Data compression in wireless sensors network using MDCT and embedded harmonic coding.

    PubMed

    Alsalaet, Jaafar K; Ali, Abduladhem A

    2015-05-01

    One of the major applications of wireless sensors networks (WSNs) is vibration measurement for the purpose of structural health monitoring and machinery fault diagnosis. WSNs have many advantages over the wired networks such as low cost and reduced setup time. However, the useful bandwidth is limited, as compared to wired networks, resulting in relatively low sampling. One solution to this problem is data compression which, in addition to enhancing sampling rate, saves valuable power of the wireless nodes. In this work, a data compression scheme, based on Modified Discrete Cosine Transform (MDCT) followed by Embedded Harmonic Components Coding (EHCC) is proposed to compress vibration signals. The EHCC is applied to exploit harmonic redundancy present is most vibration signals resulting in improved compression ratio. This scheme is made suitable for the tiny hardware of wireless nodes and it is proved to be fast and effective. The efficiency of the proposed scheme is investigated by conducting several experimental tests.

  7. A novel scheme for detection of diffuse lung disease in MDCT by use of statistical texture features

    NASA Astrophysics Data System (ADS)

    Wang, Jiahui; Li, Feng; Doi, Kunio; Li, Qiang

    2009-02-01

    The successful development of high performance computer-aided-diagnostic systems has potential to assist radiologists in the detection and diagnosis of diffuse lung disease. We developed in this study an automated scheme for the detection of diffuse lung disease on multi-detector computed tomography (MDCT). Our database consisted of 68 CT scans, which included 31 normal and 37 abnormal cases with three kinds of abnormal patterns, i.e., ground glass opacity, reticular, and honeycombing. Two radiologists first selected the CT scans with abnormal patterns based on clinical reports. The areas that included specific abnormal patterns in the selected CT images were then delineated as reference standards by an expert chest radiologist. To detect abnormal cases with diffuse lung disease, the lungs were first segmented from the background in each slice by use of a texture analysis technique, and then divided into contiguous volumes of interest (VOIs) with a 64×64×64 matrix size. For each VOI, we calculated many statistical texture features, including the mean and standard deviation of CT values, features determined from the run length matrix, and features from the co-occurrence matrix. A quadratic classifier was employed for distinguishing between normal and abnormal VOIs by use of a leave-one-case-out validation scheme. A rule-based criterion was employed to further determine whether a case was normal or abnormal. For the detection of abnormal VOIs, our CAD system achieved a sensitivity of 86% and a specificity of 90%. For the detection of abnormal cases, it achieved a sensitivity of 89% and a specificity of 90%. This preliminary study indicates that our CAD system would be useful for the detection of diffuse lung disease.

  8. Arterial double-contrast dual-energy MDCT: in-vivo rabbit atherosclerosis with iodinated nanoparticles and gadolinium agents

    NASA Astrophysics Data System (ADS)

    Carmi, Raz; Kafri, Galit; Altman, Ami; Goshen, Liran; Planer, David; Sosna, Jacob

    2010-03-01

    An in-vivo feasibility study of potentially improved atherosclerosis CT imaging is presented. By administration of two different contrast agents to rabbits with induced atherosclerotic plaques we aim at identifying both soft plaque and vessel lumen simultaneously. Initial injection of iodinated nanoparticle (INP) contrast agent (N1177 - Nanoscan Imaging), two to four hours before scan, leads to its later accumulation in macrophage-rich soft plaque, while a second gadolinium contrast agent (Magnevist) injected immediately prior to the scan blends with the aortic blood. The distinction between the two agents in a single scan is achieved with a double-layer dual-energy MDCT (Philips Healthcare) following material separation analysis using the reconstructed images of the different x-ray spectra. A single contrast agent injection scan, where only INP was injected two hours prior to the scan, was compared to a double-contrast scan taken four hours after INP injection and immediately after gadolinium injection. On the single contrast agent scan we observed along the aorta walls, localized iodine accumulation which can point on INP uptake by atherosclerotic plaque. In the double-contrast scan the gadolinium contributes a clearer depiction of the vessel lumen in addition to the lasting INP presence. The material separation shows a good correlation to the pathologies inferred from the conventional CT images of the two different scans while performing only a single scan prevents miss-registration problems and reduces radiation dose. These results suggest that a double-contrast dual-energy CT may be used for advanced clinical diagnostic applications.

  9. Multidetector computed tomography (MDCT) evaluation of myocardial viability: intraindividual comparison of monomeric vs. dimeric contrast media in a rabbit model.

    PubMed

    Mahnken, Andreas H; Jost, Gregor; Bruners, Philipp; Sieber, Martin; Seidensticker, Peter R; Günther, Rolf W; Pietsch, Hubertus

    2009-02-01

    To evaluate the influence of different types of iodinated contrast media on the assessment of myocardial viability, acute myocardial infarction (MI) was surgically induced in six rabbits. Over a period of 45 min, contrast-enhanced cardiac MDCT (64 x 0.6 mm, 80 kV, 680 mAs(eff.)) was repeatedly performed using a contrast medium dose of 600 mg iodine/kg body weight. Animals received randomized iopromide 300 and iodixanol 320, respectively. Attenuation values of healthy and infarcted myocardium were measured. The size of MI was computed and compared with nitroblue tetrazolium (NBT)-stained specimen. The highest attenuation differences between infarcted and healthy myocardium occurred during the arterial phase with 140.0+/-3.5 HU and 141.0+/-2.2 HU for iopromide and iodixanol, respectively. For iodixanol the highest attenuation difference on delayed contrast-enhanced images was achieved 3 min post injection (73.5 HU). A slightly higher attenuation difference was observed for iopromide 6 min after contrast medium injection (82.2 HU), although not statistically significant (p=0.6437). Mean infarct volume as measured by NBT staining was 33.5%+/-13.6%. There was an excellent agreement of infarct sizes among NBT-, iopromide- and iodixanol-enhanced MDCT with concordance-correlation coefficients ranging from rho(c)=0.9928-0.9982. Iopromide and iodixanol both allow a reliable assessment of MI with delayed contrast-enhanced MDCT.

  10. Extramural venous invasion detected by MDCT as an adverse imaging feature for predicting synchronous metastases in T4 gastric cancer.

    PubMed

    Cheng, Jin; Wu, Jing; Ye, Yingjiang; Zhang, Chunfang; Zhang, Yinli; Wang, Yi

    2017-04-01

    Background Extramural venous invasion (EMVI) is defined histologically as the active invasion of tumor cells to the lumens of mesenteric vessels beyond the muscularis propria in advanced gastrointestinal cancer, resulting in distant metastases. Purpose To determine the association between synchronous metastatic disease in patients with T4 gastric cancer and EMVI detected on contrast-enhanced multiple-row detector computed tomography (MDCT). Material and Methods A total of 152 patients with T4 gastric carcinoma were retrospectively reviewed and divided into EMVI-positive and EMVI-negative groups where EMVI, as detected on MDCT, was defined as a tubular or nodular soft tissue thickening extending from the tumor along the vessels of the mesentery. Synchronous metastases were detected by MDCT and/or confirmed by postoperative diagnosis. Logistic regression analyses were performed to analyze the predictive factors of synchronous metastases in gastric cancer. Results Synchronous metastases were found in 47 of 152 (30.9%) patients with T4 gastric cancer. Thirty-one of 77 (40.3%) patients in the EMVI-positive group had evidence of metastases compared to 16 (21.3%) of 75 patients in the EMVI-negative group ( P = 0.019). Synchronous metastases were significantly associated with EMVI with an odds ratio (OR) of 2.250 (95% CI, 1.072-4.724). Conclusion EMVI-positive tumors, as an adverse imaging feature, were significantly associated with synchronous metastases in patients with T4 gastric cancer.

  11. Morphological and functional MDCT: problem-solving tool and surrogate biomarker for hepatic disease clinical care and drug discovery in the era of personalized medicine.

    PubMed

    Wang, Liang

    2010-08-17

    This article explains the significant role of morphological and functional multidetector computer tomography (MDCT) in combination with imaging postprocessing algorithms served as a problem-solving tool and noninvasive surrogate biomarker to effectively improve hepatic diseases characterization, detection, tumor staging and prognosis, therapy response assessment, and novel drug discovery programs, partial liver resection and transplantation, and MDCT-guided interventions in the era of personalized medicine. State-of-the-art MDCT depicts and quantifies hepatic disease over conventional CT for not only depicting lesion location, size, and extent but also detecting changes in tumor biologic behavior caused by therapy or tumor progression before morphologic changes. Color-encoded parameter display provides important functional information on blood flow, permeability, leakage space, and blood volume. Together with other relevant biomarkers and genomics, the imaging modality is being developed and validated as a biomarker to early response to novel, targeted anti-VEGF(R)/PDGFR or antivascular/angiogenesis agents as its parameters correlate with immunohistochemical surrogates of tumor angiogenesis and molecular features of malignancies. MDCT holds incremental value to World Health Organization response criteria and Response Evaluation Criteria in Solid Tumors in liver disease management. MDCT volumetric measurement of future remnant liver is the most important factor influencing the outcome of patients who underwent partial liver resection and transplantation. MDCT-guided interventional methods deliver personalized therapies locally in the human body. MDCT will hold more scientific impact when it is fused with other imaging probes to yield comprehensive information regarding changes in liver disease at different levels (anatomic, metabolic, molecular, histologic, and other levels).

  12. Celiac Axis, Common Hepatic and Hepatic Artery Variants as Evidenced on MDCT Angiography in South Indian Population

    PubMed Central

    Parthasarathy, Ramesh

    2016-01-01

    Introduction With the increase in the hepatobiliary, pancreatic surgeries and liver transplantation, being aware of the anatomic variations of the celiac axis and the hepatic arteries is of paramount importance. Aim To illustrate the normal anatomy and variants of the celiac axis and the hepatic arteries with multidetector computed tomographic (MDCT) angiography in South Indian population and determine the potential variations in the celiac axis anatomy and the hepatic arteries, thus assisting the hepatobiliary surgeon and the interventional radiologist in avoiding iatrogenic injury to the arteries. Materials and Methods Two hundred patients undergoing abdominal CT angiography from July 2014 till July 2015 were retrospectively studied for hepatic arterial and celiac axis anatomical variation. The anatomic variations in our study were correlated with other studies. Results The celiac axis (CA) and the hepatic artery (HA) variations were analysed as per criteria laid by Song et al., and Michel. Out of 15 possible CA variations, 5 types of celiac artery variations were seen in 14 patients. A normal CA was seen in 179(89.5%) patients of the 200 patients. In the remaining 7 patients, the CA anatomy was classified as ambiguous since there was separate origin of the right and left hepatic arteries from the CA with absent common hepatic artery (CHA). The CHA originated normally from the celiac axis in 94% of the cases. Variation of CHA origin was seen in 5 patients. Normal HA anatomy was seen in 114 (57%) patients. Variation in HA anatomy was seen in 86 (43%) patients. Origin of the right hepatic artery (RHA) from the hepatic artery proper was seen in 182 (91%) patients and replaced origin of RHA from the superior mesenteric artery (SMA) was seen in 18 (9%) of the cases. Accessory RHA was seen in 7(3.5%) patients. The left hepatic artery (LHA) originated from the hepatic artery proper in 186 (93%) patients and replaced origin of LHA from the left gastric artery (LGA) was

  13. A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

    SciTech Connect

    Yin, Youbing; Choi, Jiwoong; Hoffman, Eric A.; Tawhai, Merryn H.; Lin, Ching-Long

    2013-07-01

    A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C{sub 1} continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung.

  14. A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

    NASA Astrophysics Data System (ADS)

    Yin, Youbing; Choi, Jiwoong; Hoffman, Eric A.; Tawhai, Merryn H.; Lin, Ching-Long

    2013-07-01

    A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C1 continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung.

  15. Automated diagnosis of interstitial lung diseases and emphysema in MDCT imaging

    NASA Astrophysics Data System (ADS)

    Fetita, Catalin; Chang Chien, Kuang-Che; Brillet, Pierre-Yves; Prêteux, Françoise

    2007-09-01

    Diffuse lung diseases (DLD) include a heterogeneous group of non-neoplasic disease resulting from damage to the lung parenchyma by varying patterns of inflammation. Characterization and quantification of DLD severity using MDCT, mainly in interstitial lung diseases and emphysema, is an important issue in clinical research for the evaluation of new therapies. This paper develops a 3D automated approach for detection and diagnosis of diffuse lung diseases such as fibrosis/honeycombing, ground glass and emphysema. The proposed methodology combines multi-resolution 3D morphological filtering (exploiting the sup-constrained connection cost operator) and graph-based classification for a full characterization of the parenchymal tissue. The morphological filtering performs a multi-level segmentation of the low- and medium-attenuated lung regions as well as their classification with respect to a granularity criterion (multi-resolution analysis). The original intensity range of the CT data volume is thus reduced in the segmented data to a number of levels equal to the resolution depth used (generally ten levels). The specificity of such morphological filtering is to extract tissue patterns locally contrasting with their neighborhood and of size inferior to the resolution depth, while preserving their original shape. A multi-valued hierarchical graph describing the segmentation result is built-up according to the resolution level and the adjacency of the different segmented components. The graph nodes are then enriched with the textural information carried out by their associated components. A graph analysis-reorganization based on the nodes attributes delivers the final classification of the lung parenchyma in normal and ILD/emphysematous regions. It also makes possible to discriminate between different types, or development stages, among the same class of diseases.

  16. The most characteristic lesions and radiologic signs of Crohn disease of the small bowel: air enteroclysis, MDCT, endoscopy, and pathology.

    PubMed

    Carbo, Alberto I; Reddy, Threta; Gates, Thomas; Vesa, Telciane; Thomas, Jaiyeola; Gonzalez, Enrique

    2014-02-01

    This pictorial essay describes the most characteristic lesions and radiologic signs of Crohn disease of the small bowel: nodular lymphoid hyperplasia, abnormal mucosal folds, villous pattern, aphthous ulcerations, linear ulcerations, cobblestone pattern, string sign, target sign, comb sign, creeping fat, sinus tracts, fistulas, and abscesses. Each description includes the definition, a correlation with the pathologic findings, an explanation of the possible physiopathologic mechanism, sample radiologic images with air enteroclysis or MDCT, the correspondence with the endoscopic findings when possible, and a list of differential diagnoses.

  17. Synchronous infection of the aorta and the testis: emphysematous epididymo-orchitis, abdominal aortic mycotic aneurysm, and testicular artery pseudoaneurysm diagnosed by use of MDCT.

    PubMed

    Hegde, Rahul G; Balani, Ankit; Merchant, Suleman A; Joshi, Anagha R

    2014-07-01

    We report clinical details and imaging findings for a case of emphysematous epididymo-orchitis with co-existing mycotic abdominal aortic aneurysm and a testicular artery pseudoaneurysm in a diabetic 65-year-old male. We report imaging findings from ultrasonography (USG) and contrast-enhanced multidetector computed tomography (MDCT). Use of MDCT to identify, confirm, and define the extent of the disease, and its utility in understanding the pathogenesis of this rare condition are highlighted. For such lethal infections, early diagnosis and intervention can be lifesaving; imaging can be of crucial importance in this.

  18. MDCT Anatomic Assessment of Right Inferior Phrenic Artery Origin Related to Potential Supply to Hepatocellular Carcinoma and its Embolization

    SciTech Connect

    Basile, Antonio Tsetis, Dimitrios; Montineri, Arturo; Puleo, Stefano; Massa Saluzzo, Cesare; Runza, Giuseppe; Coppolino, Francesco; Ettorre, Giovanni Carlo; Patti, Maria Teresa

    2008-03-15

    Purpose. To prospectively assess the anatomic variation of the right inferior phrenic artery (RIPA) origin with multidetector computed tomography (MDCT) scans in relation to the technical and angiographic findings during transcatheter arterial embolization of hepatocellular carcinoma (HCC). Methods. Two hundred patients with hepatocellular carcinomas were examined with 16-section CT during the arterial phase. The anatomy of the inferior phrenic arteries was recorded, with particular reference to their origin. All patients with subcapsular HCC located at segments VII and VIII underwent arteriography of the RIPA with subsequent embolization if neoplastic supply was detected. Results. The RIPA origin was detected in all cases (sensitivity 100%), while the left inferior phrenic artery origin was detected in 187 cases (sensitivity 93.5%). RIPAs originated from the aorta (49%), celiac trunk (41%), right renal artery (5.5%), left gastric artery (4%), and proper hepatic artery (0.5%), with 13 types of combinations with the left IPA. Twenty-nine patients showed subcapsular HCCs in segments VII and VIII and all but one underwent RIPA selective angiography, followed by embolization in 7 cases. Conclusion. MDCT assesses well the anatomy of RIPAs, which is fundamental for planning subsequent cannulation and embolization of extrahepatic RIPA supply to HCC.

  19. Pelvic ultrasound immediately following MDCT in female patients with abdominal/pelvic pain: is it always necessary?

    PubMed

    Yitta, Silaja; Mausner, Elizabeth V; Kim, Alice; Kim, Danny; Babb, James S; Hecht, Elizabeth M; Bennett, Genevieve L

    2011-10-01

    To determine the added value of reimaging the female pelvis with ultrasound (US) immediately following multidetector CT (MDCT) in the emergent setting. CT and US exams of 70 patients who underwent MDCT for evaluation of abdominal/pelvic pain followed by pelvic ultrasound within 48 h were retrospectively reviewed by three readers. Initially, only the CT images were reviewed followed by evaluation of CT images in conjunction with US images. Diagnostic confidence was recorded for each reading and an exact Wilcoxon signed rank test was performed to compare the two. Changes in diagnosis based on combined CT and US readings versus CT readings alone were identified. Confidence intervals (95%) were derived for the percentage of times US reimaging can be expected to lead to a change in diagnosis relative to the diagnosis based on CT interpretation alone. Ultrasound changed the diagnosis for the ovaries/adnexa 8.1% of the time (three reader average); the majority being cases of a suspected CT abnormality found to be normal on US. Ultrasound changed the diagnosis for the uterus 11.9% of the time (three reader average); the majority related to the endometrial canal. The 95% confidence intervals for the ovaries/adnexa and uterus were 5-12.5% and 8-17%, respectively. Ten cases of a normal CT were followed by a normal US with 100% agreement across all three readers. Experienced readers correctly diagnosed ruptured ovarian cysts and tubo-ovarian abscesses (TOA) based on CT alone with 100% agreement. US reimaging after MDCT of the abdomen and pelvis is not helpful: (1) following a normal CT of the pelvic organs or (2) when CT findings are diagnostic and/or characteristic of certain entities such as ruptured cysts and TOA. Reimaging with ultrasound is warranted for (1) less-experienced readers to improve diagnostic confidence or when CT findings are not definitive, (2) further evaluation of suspected endometrial abnormalities. A distinction should be made between the need for

  20. Radiological surveillance of formerly asbestos-exposed power industry workers: rates and risk factors of benign changes on chest X-ray and MDCT

    PubMed Central

    2014-01-01

    Background To determine the prevalence of asbestos-related changes on chest X-ray (CXR) and low-dose multidetector-row CT (MDCT) of the thorax in a cohort of formerly asbestos-exposed power industry workers and to assess the importance of common risk factors associated with specific radiological changes. Methods To assess the influence of selected risk factors (age, time since first exposure, exposure duration, cumulative exposure and pack years) on typical asbestos-related radiographic changes, we employed multiple logistic regression and receiver operating characteristic (ROC) analysis. Results On CXR, pleural changes and asbestosis were strongly associated with age, years since first exposure and exposure duration. The MDCT results showed an association between asbestosis and age and between plaques and exposure duration, years since first exposure and cumulative exposure. Parenchymal changes on CXR and MDCT, and diffuse pleural thickening on CXR were both associated with smoking. Using a cut-off of 55 years for age, 17 years for exposure duration and 28 years for latency, benign radiological changes in the cohort with CXR could be predicted with a sensitivity of 82.0% for all of the three variables and a specificity of 47.4%, 39.0% and 40.6%, respectively. Conclusions Participants aged 55 years and older and those with an asbestos exposure of at least 17 years or 28 years since first exposure should be seen as having an increased risk of abnormal radiological findings. For implementing a more focused approach the routine use of low-dose MDCT rather than CXR at least for initial examinations would be justified. PMID:24808921

  1. Evaluation of organ doses and specific k effective dose of 64-slice CT thorax examination using an adult anthropomorphic phantom

    NASA Astrophysics Data System (ADS)

    Hashim, S.; Karim, M. K. A.; Bakar, K. A.; Sabarudin, A.; Chin, A. W.; Saripan, M. I.; Bradley, D. A.

    2016-09-01

    The magnitude of radiation dose in computed tomography (CT) depends on the scan acquisition parameters, investigated herein using an anthropomorphic phantom (RANDO®) and thermoluminescence dosimeters (TLD). Specific interest was in the organ doses resulting from CT thorax examination, the specific k coefficient for effective dose estimation for particular protocols also being determined. For measurement of doses representing five main organs (thyroid, lung, liver, esophagus and skin), TLD-100 (LiF:Mg, Ti) were inserted into selected holes in a phantom slab. Five CT thorax protocols were investigated, one routine (R1) and four that were modified protocols (R2 to R5). Organ doses were ranked from greatest to least, found to lie in the order: thyroid>skin>lung>liver>breast. The greatest dose, for thyroid at 25 mGy, was that in use of R1 while the lowest, at 8.8 mGy, was in breast tissue using R3. Effective dose (E) was estimated using three standard methods: the International Commission on Radiological Protection (ICRP)-103 recommendation (E103), the computational phantom CT-EXPO (E(CTEXPO)) method, and the dose-length product (DLP) based approach. E103 k factors were constant for all protocols, ~8% less than that of the universal k factor. Due to inconsistency in tube potential and pitch factor the k factors from CTEXPO were found to vary between 0.015 and 0.010 for protocols R3 and R5. With considerable variation between scan acquisition parameters and organ doses, optimization of practice is necessary in order to reduce patient organ dose.

  2. Associations Between Cardio-Ankle Vascular Index and Aortic Structure and Sclerosis Using Multidetector Computed Tomography.

    PubMed

    Horinaka, Shigeo; Yagi, Hiroshi; Fukushima, Hiromichi; Shibata, Yoshimasa; Takeshima, Hiroshi; Ishimitsu, Toshihiko

    2017-04-01

    Aortic pulse wave velocity (PWV) has been accepted as the gold standard for arterial stiffness measurement. However, PWV depends on blood pressure (BP). To eliminate the BP dependency of PWV, the cardio-ankle vascular index (CAVI) was developed. This study aimed to define the relationship between CAVI and aortic atherosclerosis or structure on multidetector computed tomography (MDCT). Patients with (n = 49) or without (n = 49) coronary artery disease were studied. The lumen and vessel diameters and wall thickness were calculated from the cross-sectional area at the pulmonary bifurcation level by 64-slice MDCT. The CAVI was measured within 3 days before MDCT. Multivariate analysis showed that the vessel diameter of the ascending and descending aorta on MDCT depends on age, body surface area, and diastolic BP. The CAVI significantly correlated with the vessel diameter ( r = .453) and wall thickness ( r = .387) of the thoracic descending aorta ( P < .001, respectively). The CAVI was an independent predictor of the descending aortic wall thickness on multiple stepwise regression analysis. These data suggest that CAVI, a simple index, is useful for evaluating thoracic aortic atherosclerosis.

  3. Radiofrequency Ablation of Liver Metastases-Software-Assisted Evaluation of the Ablation Zone in MDCT: Tumor-Free Follow-Up Versus Local Recurrent Disease

    SciTech Connect

    Keil, Sebastian Bruners, Philipp; Schiffl, Katharina; Sedlmair, Martin; Muehlenbruch, Georg; Guenther, Rolf W.; Das, Marco; Mahnken, Andreas H.

    2010-04-15

    The purpose of this study was to investigate differences in change of size and CT value between local recurrences and tumor-free areas after CT-guided radiofrequency ablation (RFA) of hepatic metastases during follow-up by means of dedicated software for automatic evaluation of hepatic lesions. Thirty-two patients with 54 liver metastases from breast or colorectal cancer underwent triphasic contrast-enhanced multidetector-row computed tomography (MDCT) to evaluate hepatic metastatic spread and localization before CT-guided RFA and for follow-up after intervention. Sixteen of these patients (65.1 {+-} 10.3 years) with 30 metastases stayed tumor-free (group 1), while the other group (n = 16 with 24 metastases; 62.0 {+-} 13.8 years) suffered from local recurrent disease (group 2). Applying an automated software tool (SyngoCT Oncology; Siemens Healthcare, Forchheim, Germany), size parameters (volume, RECIST, WHO) and attenuation were measured within the lesions before, 1 day after, and 28 days after RFA treatment. The natural logarithm (ln) of the quotient of the volume 1 day versus 28 days after RFA treament was computed: lnQ1//28/0{sub volume}. Analogously, ln ratios of RECIST, WHO, and attenuation were computed and statistically evaluated by repeated-measures ANOVA. One lesion in group 2 was excluded from further evaluation due to automated missegmentation. Statistically significant differences between the two groups were observed with respect to initial volume, RECIST, and WHO (p < 0.05). Furthermore, ln ratios corresponding to volume, RECIST, and WHO differed significantly between the two groups. Attenuation evaluations showed no significant differences, but there was a trend toward attenuation assessment for the parameter lnQ28/0{sub attenuation} (p = 0.0527), showing higher values for group 1 (-0.4 {+-} 0.3) compared to group 2 (-0.2 {+-} 0.2). In conclusion, hepatic metastases and their zone of coagulation necrosis after RFA differed significantly between tumor

  4. Simultaneous screening for osteoporosis at CT colonography: bone mineral density assessment using MDCT attenuation techniques compared with the DXA reference standard.

    PubMed

    Pickhardt, Perry J; Lee, Lawrence J; del Rio, Alejandro Muñoz; Lauder, Travis; Bruce, Richard J; Summers, Ron M; Pooler, B Dustin; Binkley, Neil

    2011-09-01

    The purpose of this study was to evaluate the utility of lumbar spine attenuation measurement for bone mineral density (BMD) assessment at screening computed tomographic colonography (CTC) using central dual-energy X-ray absorptiometry (DXA) as the reference standard. Two-hundred and fifty-two adults (240 women and 12 men; mean age 58.9 years) underwent CTC screening and central DXA BMD measurement within 2 months (mean interval 25.0 days). The lowest DXA T-score between the spine and hip served as the reference standard, with low BMD defined per World Health Organization as osteoporosis (DXA T-score ≤ -2.5) or osteopenia (DXA T-score between -1.0 and -2.4). Both phantomless quantitative computed tomography (QCT) and simple nonangled region-of-interest (ROI) multi-detector CT (MDCT) attenuation measurements were applied to the T(12) -L(5) levels. The ability to predict osteoporosis and low BMD (osteoporosis or osteopenia) by DXA was assessed. A BMD cut-off of 90 mg/mL at phantomless QCT yielded 100% sensitivity for osteoporosis (29 of 29) and a specificity of 63.8% (143 of 224); 87.2% (96 of 110) below this threshold had low BMD and 49.6% (69 of 139) above this threshold had normal BMD at DXA. At L(1) , a trabecular ROI attenuation cut-off of 160 HU was 100% sensitive for osteoporosis (29 of 29), with a specificity of 46.4% (104 of 224); 83.9% (125 of 149) below this threshold had low BMD and 57.5% (59/103) above had normal BMD at DXA. ROI performance was similar at all individual T(12) -L(5) levels. At ROC analysis, AUC for osteoporosis was 0.888 for phantomless QCT [95% confidence interval (CI) 0.780-0.946] and ranged from 0.825 to 0.853 using trabecular ROIs at single lumbar levels (0.864; 95% CI 0.752-0.930 at multivariate analysis). Supine-prone reproducibility was better with the simple ROI method compared with QCT. It is concluded that both phantomless QCT and simple ROI attenuation measurements of the lumbar spine are effective for BMD screening at CTC

  5. Radiofrequency ablation of liver metastases-software-assisted evaluation of the ablation zone in MDCT: tumor-free follow-up versus local recurrent disease.

    PubMed

    Keil, Sebastian; Bruners, Philipp; Schiffl, Katharina; Sedlmair, Martin; Mühlenbruch, Georg; Günther, Rolf W; Das, Marco; Mahnken, Andreas H

    2010-04-01

    The purpose of this study was to investigate differences in change of size and CT value between local recurrences and tumor-free areas after CT-guided radiofrequency ablation (RFA) of hepatic metastases during follow-up by means of dedicated software for automatic evaluation of hepatic lesions. Thirty-two patients with 54 liver metastases from breast or colorectal cancer underwent triphasic contrast-enhanced multidetector-row computed tomography (MDCT) to evaluate hepatic metastatic spread and localization before CT-guided RFA and for follow-up after intervention. Sixteen of these patients (65.1 + or - 10.3 years) with 30 metastases stayed tumor-free (group 1), while the other group (n = 16 with 24 metastases; 62.0 + or - 13.8 years) suffered from local recurrent disease (group 2). Applying an automated software tool (SyngoCT Oncology; Siemens Healthcare, Forchheim, Germany), size parameters (volume, RECIST, WHO) and attenuation were measured within the lesions before, 1 day after, and 28 days after RFA treatment. The natural logarithm (ln) of the quotient of the volume 1 day versus 28 days after RFA treament was computed: lnQ1//28/0(volume). Analogously, ln ratios of RECIST, WHO, and attenuation were computed and statistically evaluated by repeated-measures ANOVA. One lesion in group 2 was excluded from further evaluation due to automated missegmentation. Statistically significant differences between the two groups were observed with respect to initial volume, RECIST, and WHO (p < 0.05). Furthermore, ln ratios corresponding to volume, RECIST, and WHO differed significantly between the two groups. Attenuation evaluations showed no significant differences, but there was a trend toward attenuation assessment for the parameter lnQ28/0(attenuation) (p = 0.0527), showing higher values for group 1 (-0.4 + or - 0.3) compared to group 2 (-0.2 + or - 0.2). In conclusion, hepatic metastases and their zone of coagulation necrosis after RFA differed significantly between tumor

  6. Assessment of trabecular bone structure of the calcaneus using multi-detector CT: correlation with microCT and biomechanical testing.

    PubMed

    Diederichs, Gerd; Link, Thomas M; Kentenich, Marie; Schwieger, Karsten; Huber, Markus B; Burghardt, Andrew J; Majumdar, Sharmila; Rogalla, Patrik; Issever, Ahi S

    2009-05-01

    The prediction of bone strength can be improved when determining bone mineral density (BMD) in combination with measures of trabecular microarchitecture. The goal of this study was to assess parameters of trabecular bone structure and texture of the calcaneus by clinical multi-detector row computed tomography (MDCT) in an experimental in situ setup and to correlate these parameters with microCT (microCT) and biomechanical testing. Thirty calcanei in 15 intact cadavers were scanned using three different protocols on a 64-slice MDCT scanner with an in-plane pixel size of 208 microm and 500 microm slice thickness. Bone cores were harvested from each specimen and microCT images with a voxel size of 16 microm were obtained. After image coregistration, trabecular bone structure and texture were evaluated in identical regions on the MDCT images. After data acquisition, uniaxial compression testing was performed. Significant correlations between MDCT- and microCT-derived measures of bone volume fraction (BV/TV), trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp) were found (range, R(2)=0.19-0.65, p<0.01 or 0.05). The MDCT-derived parameters of volumetric BMD, app. BV/TV, app. Tb.Th and app. Tb.Sp were capable of predicting 60%, 63%, 53% and 25% of the variation in bone strength (p<0.01). When combining those measures with one additional texture index (either GLCM, TOGLCM or MF.euler), prediction of mechanical competence was significantly improved to 86%, 85%, 71% and 63% (p<0.01). In conclusion, this study showed the feasibility of trabecular microarchitecture assessment using MDCT in an experimental setup simulating the clinical situation. Multivariate models of BMD or structural parameters combined with texture indices improved prediction of bone strength significantly and might provide more reliable estimates of fracture risk in patients.

  7. Radiation dose from MDCT using Monte Carlo simulations: estimating fetal dose due to pulmonary embolism scans accounting for overscan

    NASA Astrophysics Data System (ADS)

    Angel, E.; Wellnitz, C.; Goodsitt, M.; DeMarco, J.; Cagnon, C.; Ghatali, M.; Cody, D.; Stevens, D.; McCollough, C.; Primak, A.; McNitt-Gray, M.

    2007-03-01

    Pregnant women with shortness of breath are increasingly referred for CT Angiography to rule out Pulmonary Embolism (PE). While this exam is typically focused on the lungs, extending scan boundaries and overscan can add to the irradiated volume and have implications on fetal dose. The purpose of this work was to estimate radiation dose to the fetus when various levels of overscan were encountered. Two voxelized models of pregnant patients derived from actual patient anatomy were created based on image data. The models represent an early (< 7 weeks) and late term pregnancy (36 weeks). A previously validated Monte Carlo model of an MDCT scanner was used that takes into account physical details of the scanner. Simulated helical scans used 120 kVp, 4x5 mm beam collimation, pitch 1, and varying beam-off locations (edge of the irradiated volume) were used to represent different protocols plus overscan. Normalized dose (mGy/100mAs) was calculated for each fetus. For the early term and the late term pregnancy models, fetal dose estimates for a standard thoracic PE exam were estimated to be 0.05 and 0.3 mGy/100mAs, respectively, increasing to 9 mGy/100mAs when the beam-off location was extended to encompass the fetus. When performing PE exams to rule out PE in pregnant patients, the beam-off location may have a large effect on fetal dose, especially for late term pregnancies. Careful consideration of ending location of the x-ray beam - and not the end of image data - could result in significant reduction in radiation dose to the fetus.

  8. Longitudinal changes in structural abnormalities using MDCT in COPD: do the CT measurements of airway wall thickness and small pulmonary vessels change in parallel with emphysematous progression?

    PubMed Central

    Takayanagi, Shin; Kawata, Naoko; Tada, Yuji; Ikari, Jun; Matsuura, Yukiko; Matsuoka, Shin; Matsushita, Shoichiro; Yanagawa, Noriyuki; Kasahara, Yasunori; Tatsumi, Koichiro

    2017-01-01

    Background Recent advances in multidetector computed tomography (MDCT) facilitate acquiring important clinical information for managing patients with COPD. MDCT can detect the loss of lung tissue associated with emphysema as a low-attenuation area (LAA) and the thickness of airways as the wall area percentage (WA%). The percentage of small pulmonary vessels <5 mm2 (% cross-sectional area [CSA] <5) has been recently recognized as a parameter for expressing pulmonary perfusion. We aimed to analyze the longitudinal changes in structural abnormalities using these CT parameters and analyze the effect of exacerbation and smoking cessation on structural changes in COPD patients. Methods We performed pulmonary function tests (PFTs), an MDCT, and a COPD assessment test (CAT) in 58 patients with COPD at the time of their enrollment at the hospital and 2 years later. We analyzed the change in clinical parameters including CT indices and examined the effect of exacerbations and smoking cessation on the structural changes. Results The CAT score and forced expiratory volume in 1 second (FEV1) did not significantly change during the follow-up period. The parameters of emphysematous changes significantly increased. On the other hand, the WA% at the distal airways significantly decreased or tended to decrease, and the %CSA <5 slightly but significantly increased over the same period, especially in ex-smokers. The parameters of emphysematous change were greater in patients with exacerbations and continued to progress even after smoking cessation. In contrast, the WA% and %CSA <5 did not change in proportion to emphysema progression. Conclusion The WA% at the distal bronchi and the %CSA <5 did not change in parallel with parameters of LAA over the same period. We propose that airway disease and vascular remodeling may be reversible to some extent by smoking cessation and appropriate treatment. Optimal management may have a greater effect on pulmonary vascularity and airway disease

  9. Left ventricular remodelling and systolic function measurement with 64 multi-slice computed tomography versus second harmonic echocardiography in patients with coronary artery disease: a double blind study.

    PubMed

    Palazzuoli, Alberto; Cademartiri, Filippo; Geleijnse, Marcel L; Meijboom, Bob; Pugliese, Francesca; Soliman, Osama; Calabrò, Anna; Nuti, Ranuccio; de Feyter, Pim

    2010-01-01

    The present study evaluated LV volumes, ejection fraction (LVEF) and stroke volume (SV) obtained by 64-MDCT and to compare these data with those obtained by second harmonic 2D Echo, in patients referred for non-invasive coronary vessels evaluation. The most common technique in daily clinical practice used for determination of LV function is two-dimensional echocardiography (2D-TTE). Multi-detector computed tomography (MDCT) is an emerging new technique to detect coronary artery disease (CAD) and was recently proposed to assess LV function. 93 patients underwent to 64-MDCT for LV function and volumes assessment by segmental reconstruction algorithm (Argus) and compared with recent (2 months) 2D-TTE, all images were processed and interpreted by two observers blinded to the Echo and MDCT results. A close correlation between TTE and 64 MDCT was demonstrated for the ejection fraction LVEF (r=0.84), end-diastolic volume LVEDV (r=0.80) and end-systolic volume LVESV (r=0.85); acceptable correlation was recruited for stroke volume LVSV (r=0.58). Optimal results were recruited for inter-observer variability for 64-MDCT measured in 45 patients: LVESV (r=0.82, p<0.001), LVEDV (r=0.83, p<0.001), LVEF (r=0.69, p<0.002) and SV (r=0.66, p<0.001). Our results, showed that functional and temporal information contained in a coronary 64-MDCT study can be used to assess left ventricular (LV) systolic function and LV dimensions with good reproducibility and acceptable correlation respect to 2D-TTE. The combination of non-invasive coronary artery imaging and assessment of global LV function might became in the future a fast and conclusive cardiac work-up in patients with CAD.

  10. Organ dose measurements from multiple-detector computed tomography using a commercial dosimetry system and tomographic, physical phantoms

    NASA Astrophysics Data System (ADS)

    Lavoie, Lindsey K.

    The technology of computed tomography (CT) imaging has soared over the last decade with the use of multi-detector CT (MDCT) scanners that are capable of performing studies in a matter of seconds. While the diagnostic information obtained from MDCT imaging is extremely valuable, it is important to ensure that the radiation doses resulting from these studies are at acceptably safe levels. This research project focused on the measurement of organ doses resulting from modern MDCT scanners. A commercially-available dosimetry system was used to measure organ doses. Small dosimeters made of optically-stimulated luminescent (OSL) material were analyzed with a portable OSL reader. Detailed verification of this system was performed. Characteristics studied include energy, scatter, and angular responses; dose linearity, ability to erase the exposed dose and ability to reuse dosimeters multiple times. The results of this verification process were positive. While small correction factors needed to be applied to the dose reported by the OSL reader, these factors were small and expected. Physical, tomographic pediatric and adult phantoms were used to measure organ doses. These phantoms were developed from CT images and are composed of tissue-equivalent materials. Because the adult phantom is comprised of numerous segments, dosimeters were placed in the phantom at several organ locations, and doses to select organs were measured using three clinical protocols: pediatric craniosynostosis, adult brain perfusion and adult cardiac CT angiography (CTA). A wide-beam, 320-slice, volumetric CT scanner and a 64-slice, MDCT scanner were used for organ dose measurements. Doses ranged from 1 to 26 mGy for the pediatric protocol, 1 to 1241 mGy for the brain perfusion protocol, and 2-100 mGy for the cardiac protocol. In most cases, the doses measured on the 64-slice scanner were higher than those on the 320-slice scanner. A methodology to measure organ doses with OSL dosimeters received from CT

  11. The development, validation and application of a multi-detector CT (MDCT) scanner model for assessing organ doses to the pregnant patient and the fetus using Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Gu, J.; Bednarz, B.; Caracappa, P. F.; Xu, X. G.

    2009-05-01

    The latest multiple-detector technologies have further increased the popularity of x-ray CT as a diagnostic imaging modality. There is a continuing need to assess the potential radiation risk associated with such rapidly evolving multi-detector CT (MDCT) modalities and scanning protocols. This need can be met by the use of CT source models that are integrated with patient computational phantoms for organ dose calculations. Based on this purpose, this work developed and validated an MDCT scanner using the Monte Carlo method, and meanwhile the pregnant patient phantoms were integrated into the MDCT scanner model for assessment of the dose to the fetus as well as doses to the organs or tissues of the pregnant patient phantom. A Monte Carlo code, MCNPX, was used to simulate the x-ray source including the energy spectrum, filter and scan trajectory. Detailed CT scanner components were specified using an iterative trial-and-error procedure for a GE LightSpeed CT scanner. The scanner model was validated by comparing simulated results against measured CTDI values and dose profiles reported in the literature. The source movement along the helical trajectory was simulated using the pitch of 0.9375 and 1.375, respectively. The validated scanner model was then integrated with phantoms of a pregnant patient in three different gestational periods to calculate organ doses. It was found that the dose to the fetus of the 3 month pregnant patient phantom was 0.13 mGy/100 mAs and 0.57 mGy/100 mAs from the chest and kidney scan, respectively. For the chest scan of the 6 month patient phantom and the 9 month patient phantom, the fetal doses were 0.21 mGy/100 mAs and 0.26 mGy/100 mAs, respectively. The paper also discusses how these fetal dose values can be used to evaluate imaging procedures and to assess risk using recommendations of the report from AAPM Task Group 36. This work demonstrates the ability of modeling and validating an MDCT scanner by the Monte Carlo method, as well as

  12. The development, validation and application of a multi-detector CT (MDCT) scanner model for assessing organ doses to the pregnant patient and the fetus using Monte Carlo simulations.

    PubMed

    Gu, J; Bednarz, B; Caracappa, P F; Xu, X G

    2009-05-07

    The latest multiple-detector technologies have further increased the popularity of x-ray CT as a diagnostic imaging modality. There is a continuing need to assess the potential radiation risk associated with such rapidly evolving multi-detector CT (MDCT) modalities and scanning protocols. This need can be met by the use of CT source models that are integrated with patient computational phantoms for organ dose calculations. Based on this purpose, this work developed and validated an MDCT scanner using the Monte Carlo method, and meanwhile the pregnant patient phantoms were integrated into the MDCT scanner model for assessment of the dose to the fetus as well as doses to the organs or tissues of the pregnant patient phantom. A Monte Carlo code, MCNPX, was used to simulate the x-ray source including the energy spectrum, filter and scan trajectory. Detailed CT scanner components were specified using an iterative trial-and-error procedure for a GE LightSpeed CT scanner. The scanner model was validated by comparing simulated results against measured CTDI values and dose profiles reported in the literature. The source movement along the helical trajectory was simulated using the pitch of 0.9375 and 1.375, respectively. The validated scanner model was then integrated with phantoms of a pregnant patient in three different gestational periods to calculate organ doses. It was found that the dose to the fetus of the 3 month pregnant patient phantom was 0.13 mGy/100 mAs and 0.57 mGy/100 mAs from the chest and kidney scan, respectively. For the chest scan of the 6 month patient phantom and the 9 month patient phantom, the fetal doses were 0.21 mGy/100 mAs and 0.26 mGy/100 mAs, respectively. The paper also discusses how these fetal dose values can be used to evaluate imaging procedures and to assess risk using recommendations of the report from AAPM Task Group 36. This work demonstrates the ability of modeling and validating an MDCT scanner by the Monte Carlo method, as well as

  13. New absorbed dose measurement with cylindrical water phantoms for multidetector CT

    NASA Astrophysics Data System (ADS)

    Ohno, Takeshi; Araki, Fujio; Onizuka, Ryota; Hioki, Kazunari; Tomiyama, Yuuki; Yamashita, Yusuke

    2015-06-01

    The aim of this study was to develop new dosimetry with cylindrical water phantoms for multidetector computed tomography (MDCT). The ionization measurement was performed with a Farmer ionization chamber at the center and four peripheral points in the body-type and head-type cylindrical water phantoms. The ionization was converted to the absorbed dose using a 60Co absorbed-dose-to-water calibration factor and Monte Carlo (MC) -calculated correction factors. The correction factors were calculated from MDCT (Brilliance iCT, 64-slice, Philips Electronics) modeled with GMctdospp (IMPS, Germany) software based on the EGSnrc MC code. The spectrum of incident x-ray beams and the configuration of a bowtie filter for MDCT were determined so that calculated photon intensity attenuation curves for aluminum (Al) and calculated off-center ratio (OCR) profiles in air coincided with those measured. The MC-calculated doses were calibrated by the absorbed dose measured at the center in both cylindrical water phantoms. Calculated doses were compared with measured doses at four peripheral points and the center in the phantom for various beam pitches and beam collimations. The calibration factors and the uncertainty of the absorbed dose determined using this method were also compared with those obtained by CTDIair (CT dose index in air). Calculated Al half-value layers and OCRs in air were within 0.3% and 3% agreement with the measured values, respectively. Calculated doses at four peripheral points and the centers for various beam pitches and beam collimations were within 5% and 2% agreement with measured values, respectively. The MC-calibration factors by our method were 44-50% lower than values by CTDIair due to the overbeaming effect. However, the calibration factors for CTDIair agreed within 5% with those of our method after correction for the overbeaming effect. Our method makes it possible to directly measure the absorbed dose for MDCT and is more robust and accurate than the

  14. Change in the Growth Rate of Localized Pancreatic Adenocarcinoma in Response to Gemcitabine, Bevacizumab, and Radiation Therapy on MDCT

    SciTech Connect

    Rezai, Pedram; Yaghmai, Vahid; Tochetto, Sandra M.; Galizia, Mauricio S.; Miller, Frank H.; Mulcahy, Mary F.; Small, William

    2011-10-01

    Purpose: To depict treatment response to chemoradiotherapy by comparing tumor growth rate between treated and untreated patients and to compare depicted response with objective response according to the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 guideline. Methods and Materials: This Health Insurance Portability and Accountability Act-compliant, retrospective study was approved by the institutional review board. Volume doubling time (DT) of histologically confirmed locally advanced pancreatic adenocarcinoma was calculated in 16 patients treated with chemoradiotherapy and 10 untreated patients by incorporating interscan interval ({Delta}t) and tumor volume at baseline (V0) and follow-up (V1) obtained by semiautomated segmentation into the following equation: DT = {Delta}t . log 2/log (V1/V0). Reciprocal of doubling time (RDT), which is the linear representation of tumor growth rate, was calculated by use of the following equation: RDT = 365/DT. The lowest RDT value of 2.42 in untreated patients was considered as the cutoff value for depiction of treatment response. Depicted response rate was defined as the proportion of patients with an RDT value of less than 2.42. Depicted response was compared with objective response according to the RECIST 1.1 guideline. The significance level was set at p < 0.05. Results: There was a significant difference in mean RDT between treated (range, -7.12 to 3.27; mean, -1.27; median, -1.30) and untreated (range, 2.42 to 10.74; mean, 5.33; median, 4.26) patients (p < 0.05). Reciprocal of doubling time was less than 2.42 in 14 treated patients, which corresponded to a depicted response rate of 87.50% as opposed to the objective response rate of 18.75% according to the RECIST 1.1 guideline (p < 0.05) and carbohydrate antigen 19-9 response rate of 62.50% (p > 0.05). Carbohydrate antigen 19-9 response was concordant with RDT and RECIST response in 12 patients (75.00%) ({kappa}, 0.38) and 9 patients (56.25%) ({kappa}, 0

  15. The potential for non-invasive study of mummies: validation of the use of computerized tomography by post factum dissection and histological examination of a 17th century female Korean mummy.

    PubMed

    Lim, Do-Seon; Lee, In Sun; Choi, Ki-Ju; Lee, Soong Deok; Oh, Chang Seok; Kim, Yi-Suk; Bok, Gi Dae; Kim, Myeung Ju; Yi, Yang Su; Lee, Eun-Joo; Shin, Dong Hoon

    2008-10-01

    The socio-cultural antipathies of some descendants with regard to invasive examinations of age-old human remains make permission for dissection of Korean mummies of the Joseon Dynasty (1392-1910) difficult to obtain. Overcoming this obstacle necessitated the use of non-invasive techniques, such as multi-detector computerized tomography (MDCT) and endoscopic examination, enabling determination of the preservation status of internal organs of mummies without significantly damaging the mummies themselves. However, MDCT alone cannot clearly differentiate specific mummified organs. Therefore, in much the same way as diagnostic radiologists make their MDCT readings on living patients more reliable by means of comparison with accumulated post-factum data from autopsies or histological studies, examinations of mummies by invasive techniques should not be decried as mere destruction of age-old human remains. Rather, providing that due permission from descendants and/or other relevant authorities can be obtained, dissection and histological examination should be performed whenever opportunities arise. Therefore, in this study, we compared the radiological data acquired from a 17th century mummy with our dissection results for the same subject. As accumulation of this kind of data could be very crucial for correct interpretation of MDCT findings on Korean mummies, we will perform similar trials on other Korean mummies found in forthcoming days if conditions permit.

  16. The potential for non-invasive study of mummies: validation of the use of computerized tomography by post factum dissection and histological examination of a 17th century female Korean mummy

    PubMed Central

    Lim, Do-Seon; Lee, In Sun; Choi, Ki-Ju; Lee, Soong Deok; Oh, Chang Seok; Kim, Yi-Suk; Bok, Gi Dae; Kim, Myeung Ju; Yi, Yang Su; Lee, Eun-Joo; Shin, Dong Hoon

    2008-01-01

    The socio-cultural antipathies of some descendants with regard to invasive examinations of age-old human remains make permission for dissection of Korean mummies of the Joseon Dynasty (1392–1910) difficult to obtain. Overcoming this obstacle necessitated the use of non-invasive techniques, such as multi-detector computerized tomography (MDCT) and endoscopic examination, enabling determination of the preservation status of internal organs of mummies without significantly damaging the mummies themselves. However, MDCT alone cannot clearly differentiate specific mummified organs. Therefore, in much the same way as diagnostic radiologists make their MDCT readings on living patients more reliable by means of comparison with accumulated post-factum data from autopsies or histological studies, examinations of mummies by invasive techniques should not be decried as mere destruction of age-old human remains. Rather, providing that due permission from descendants and/or other relevant authorities can be obtained, dissection and histological examination should be performed whenever opportunities arise. Therefore, in this study, we compared the radiological data acquired from a 17th century mummy with our dissection results for the same subject. As accumulation of this kind of data could be very crucial for correct interpretation of MDCT findings on Korean mummies, we will perform similar trials on other Korean mummies found in forthcoming days if conditions permit. PMID:19014355

  17. COMPARATIVE STUDY OF SINGLE AND MULTISLICE COMPUTED TOMOGRAPHY FOR ASSESSMENT OF THE MANDIBULAR CANAL

    PubMed Central

    Paes, Adriana da Silva Ferreira; Moreira, Carla Ruffeil; Sales, Marcelo Augusto Oliveira; Cavalcanti, Marcelo Gusmão Paraíso

    2007-01-01

    Objective: The purpose of this study was to evaluate the accuracy of relative measurements from the roof of the mandibular canal to the alveolar crest in multislice (multidetector) computed tomography (MDCT) and single-slice computed tomography (SSCT). Material and Methods: The sample consisted of 26 printed CT films (7 SSCT and 19 MDCT) from the files of the LABI-3D (3D Imaging Laboratory) of the School of Dentistry of the University of São Paulo (FOUSP), which had been acquired using different protocols. Two observers analyzed in a randomized and independent order a series of 22 oblique CT reconstructions of each patient. Each observer analyzed the CT scans twice. The length of the mandibular canal and the distance between the mandibular canal roof and the crest of the alveolar ridge were obtained. Dahlberg test was used for statistical analysis. Results: The mean error found for the mandibular canal length measurements obtained from SSCT was 0.53 mm in the interobserver analysis, and 0.38 mm for both observers. On MDCT images, the mean error was 0.0 mm in the interobserver analysis, and 0.0 and 0.23 mm in the intraobserver analysis. Regarding the distance between the mandibular canal roof and the alveolar bone crest, the SSCT images showed a mean error of 1.16 mm in the interobserver analysis and 0.66 and 0.59 mm in the intraobserver analysis. In the MDCT images, the mean error was 0.72 mm in the interobserver analysis and 0.50 and 0.54 mm in the intraobserver analysis. Conclusion: Multislice CT was demonstrated a more accurate method and demonstrated high reproducibility in the analysis of important anatomical landmarks for planning of mandibular dental implants, namely the mandibular canal pathway and alveolar crest height. PMID:19089133

  18. Association of Neutrophil-to-Lymphocyte Ratio with the Severity and Morphology of Coronary Atherosclerotic Plaques Detected by Multidetector Computerized Tomography

    PubMed Central

    Ateş, Ahmet Hakan; Aytemir, Kudret; Koçyiğit, Duygu; Yalcin, Muhammed Ulvi; Gürses, Kadri Murat; Yorgun, Hikmet; Canpolat, Uğur; Hazırolan, Tuncay; Özer, Necla

    2016-01-01

    Background Studies have demonstrated a consistent relationship between white blood cell (WBC) counts and coronary artery disease (CAD). The neutrophil/lymphocyte ratio (NLR) has been considered as a potential marker for identifying individuals under risk of CAD and associated events. In this study, we aimed to evaluate whether NLR was associated with the severity and morphology of coronary atherosclerotic plaques shown by multidetector computed tomography (MDCT). Methods Our study population consisted of 684 patients who underwent dual-source 64 slice MDCT for the assessment of CAD. Coronary arteries were evaluated on a 16-segment basis and critical coronary plaque was described as luminal narrowing > 50%, whereas plaque morphology was assessed on a per segment basis. Total WBC, neutrophil and lymphocyte counts were determined using commercially available assay kits. Results WBC count [7700 (6400-8800) vs. 6800 (5700-7900), p < 0.05] and NLR [2.40 (1.98-3.07) vs. 1.86 (1.50-2.38), p < 0.001] were found to be higher in patients with critical stenosis than in those without. In the binary logistic regression analysis, NLR was a predictor of critical stenosis (odds ratio, 1.68; 95% confidence interval, 1.39-2.03, p < 0.001). NLR levels differed among plaque morphology subtypes (p < 0.05) and was significantly higher in non-calcified plaque (NCP) compared to mixed plaque (MP) and calcified plaque (CP) (p < 0.05). In the multinomial logistic regression analysis, NLR was found to be an independent predictor of NCP, MP and CP (p < 0.001). Conclusions These data show that NLR is associated with both the severity and morphology of coronary atherosclerotic disease. PMID:27899854

  19. Automated cortical bone segmentation for multirow-detector CT imaging with validation and application to human studies

    PubMed Central

    Li, Cheng; Jin, Dakai; Chen, Cheng; Letuchy, Elena M.; Janz, Kathleen F.; Burns, Trudy L.; Torner, James C; Levy, Steven M.; Saha, Punam K

    2015-01-01

    Purpose: Cortical bone supports and protects human skeletal functions and plays an important role in determining bone strength and fracture risk. Cortical bone segmentation at a peripheral site using multirow-detector CT (MD-CT) imaging is useful for in vivo assessment of bone strength and fracture risk. Major challenges for the task emerge from limited spatial resolution, low signal-to-noise ratio, presence of cortical pores, and structural complexity over the transition between trabecular and cortical bones. An automated algorithm for cortical bone segmentation at the distal tibia from in vivo MD-CT imaging is presented and its performance and application are examined. Methods: The algorithm is completed in two major steps—(1) bone filling, alignment, and region-of-interest computation and (2) segmentation of cortical bone. After the first step, the following sequence of tasks is performed to accomplish cortical bone segmentation—(1) detection of marrow space and possible pores, (2) computation of cortical bone thickness, detection of recession points, and confirmation and filling of true pores, and (3) detection of endosteal boundary and delineation of cortical bone. Effective generalizations of several digital topologic and geometric techniques are introduced and a fully automated algorithm is presented for cortical bone segmentation. Results: An accuracy of 95.1% in terms of volume of agreement with manual outlining of cortical bone was observed in human MD-CT scans, while an accuracy of 88.5% was achieved when compared with manual outlining on postregistered high resolution micro-CT imaging. An intraclass correlation coefficient of 0.98 was obtained in cadaveric repeat scans. A pilot study was conducted to describe gender differences in cortical bone properties. This study involved 51 female and 46 male participants (age: 19–20 yr) from the Iowa Bone Development Study. Results from this pilot study suggest that, on average after adjustment for height

  20. Multiscale topo-morphologic opening of arteries and veins: a validation study on phantoms and CT imaging of pulmonary vessel casting of pigs

    NASA Astrophysics Data System (ADS)

    Gao, Zhiyun; Holtze, Colin; Sonka, Milan; Hoffman, Eric; Saha, Punam K.

    2010-03-01

    Distinguishing pulmonary arterial and venous (A/V) trees via in vivo imaging is a critical first step in the quantification of vascular geometry for purposes of determining, for instance, pulmonary hypertension, detection of pulmonary emboli and more. A multi-scale topo-morphologic opening algorithm has recently been introduced by us separating A/V trees in pulmonary multiple-detector X-ray computed tomography (MDCT) images without contrast. The method starts with two sets of seeds - one for each of A/V trees and combines fuzzy distance transform, fuzzy connectivity, and morphologic reconstruction leading to multi-scale opening of two mutually fused structures while preserving their continuity. The method locally determines the optimum morphological scale separating the two structures. Here, a validation study is reported examining accuracy of the method using mathematically generated phantoms with different levels of fuzziness, overlap, scale, resolution, noise, and geometric coupling and MDCT images of pulmonary vessel casting of pigs. After exsanguinating the animal, a vessel cast was generated using rapid-hardening methyl methacrylate compound with additional contrast by 10cc of Ethiodol in the arterial side which was scanned in a MDCT scanner at 0.5mm slice thickness and 0.47mm in plane resolution. True segmentations of A/V trees were computed from these images by thresholding. Subsequently, effects of distinguishing A/V contrasts were eliminated and resulting images were used for A/V separation by our method. Experimental results show that 92% - 98% accuracy is achieved using only one seed for each object in phantoms while 94.4% accuracy is achieved in MDCT cast images using ten seeds for each of A/V trees.

  1. Bone Mineral Density Estimations From Routine Multidetector Computed Tomography: A Comparative Study of Contrast and Calibration Effects

    PubMed Central

    Kaesmacher, Johannes; Liebl, Hans; Baum, Thomas; Kirschke, Jan Stefan

    2017-01-01

    Introduction Phantom-based (synchronous and asynchronous) and phantomless (internal tissue calibration based) assessment of bone mineral density (BMD) in routine MDCT (multidetector computed tomography) examinations potentially allows for diagnosis of osteoporosis. Although recent studies investigated the effects of contrast-medium application on phantom-calibrated BMD measurements, it remains uncertain to what extent internal tissue-calibrated BMD measurements are also susceptible to contrast-medium associated density variation. The present study is the first to systemically evaluate BMD variations related to contrast application comparing different calibration techniques. Purpose To compare predicative performance of different calibration techniques for BMD measurements obtained from triphasic contrast-enhanced MDCT. Materials and Methods Bone mineral density was measured on nonenhanced (NE), arterial (AR) and portal-venous (PV) contrast phase MDCT images of 46 patients using synchronous (SYNC) and asynchronous (ASYNC) phantom calibration as well as internal calibration (IC). Quantitative computed tomography (QCT) served as criterion standard. Density variations were analyzed for each contrast phase and calibration technique, and respective linear fitting was performed. Results Both asynchronous calibration-derived BMD values (NE-ASYNC) and values estimated using IC (NE-IC) on NE MDCT images did reasonably well in predicting QCT BMD (root-mean-square deviation, 8.0% and 7.8%, respectively). Average NE-IC BMD was 2.7% lower when compared with QCT (P = 0.017), whereas no difference could be found for NE-ASYNC (P = 0.957). All average BMD estimates derived from contrast-enhanced scans differed significantly from QCT BMD (all P < 0.005) and led to notable systemic BMD biases (mean difference at least > 6.0 mg/mL). All regression fits revealed a consistent linear dependency (R2 range, 0.861–0.963). Overall accuracy and goodness of fit tended to decrease from AR to

  2. Experimental benchmarking of a Monte Carlo dose simulation code for pediatric CT

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Samei, Ehsan; Yoshizumi, Terry; Colsher, James G.; Jones, Robert P.; Frush, Donald P.

    2007-03-01

    In recent years, there has been a desire to reduce CT radiation dose to children because of their susceptibility and prolonged risk for cancer induction. Concerns arise, however, as to the impact of dose reduction on image quality and thus potentially on diagnostic accuracy. To study the dose and image quality relationship, we are developing a simulation code to calculate organ dose in pediatric CT patients. To benchmark this code, a cylindrical phantom was built to represent a pediatric torso, which allows measurements of dose distributions from its center to its periphery. Dose distributions for axial CT scans were measured on a 64-slice multidetector CT (MDCT) scanner (GE Healthcare, Chalfont St. Giles, UK). The same measurements were simulated using a Monte Carlo code (PENELOPE, Universitat de Barcelona) with the applicable CT geometry including bowtie filter. The deviations between simulated and measured dose values were generally within 5%. To our knowledge, this work is one of the first attempts to compare measured radial dose distributions on a cylindrical phantom with Monte Carlo simulated results. It provides a simple and effective method for benchmarking organ dose simulation codes and demonstrates the potential of Monte Carlo simulation for investigating the relationship between dose and image quality for pediatric CT patients.

  3. MDCT and 3D evaluation of type 2 hypoplastic pulmonary artery sling associated with right lung agenesis, hypoplastic aortic arch, and long segment tracheal stenosis.

    PubMed

    Lee, Edward Y

    2007-11-01

    The early diagnosis and complete anatomic evaluation of pulmonary artery sling, a congenital vascular anomaly in which left pulmonary artery arises from the right pulmonary artery, is paramount for proper patient management, because patients with this disorder frequently have other congenital anomalies resulting in high morbidity and mortality. Until recently, pulmonary artery sling in the neonate has been established with standard radiologic imaging studies such as plain radiographs, barium swallow studies, fluoroscopy-guided airway studies, and echocardiograms. However, with the development and widespread availability of multidetector computed tomography, pulmonary artery sling is increasingly evaluated with this newer technology. This case report presents a rare incidence of type 2 hypoplastic pulmonary artery sling in a neonate associated with right lung agenesis, hypoplastic aortic arch, and long segment tracheal stenosis. Multidetector computed tomography combined with 3-dimensional evaluation was particularly helpful in making a correct diagnosis of the complicated anatomic anomalies found in this case.

  4. Application of the noise power spectrum in modern diagnostic MDCT: part I. Measurement of noise power spectra and noise equivalent quanta.

    PubMed

    Boedeker, K L; Cooper, V N; McNitt-Gray, M F

    2007-07-21

    Dose reduction efforts in diagnostic CT have brought the tradeoff of dose versus image quality to the forefront. The need for meaningful characterization of image noise beyond that offered by pixel standard deviation is becoming increasingly important. This work aims to study the implementation of the noise power spectrum (NPS) and noise equivalent quanta (NEQ) on modern, multislice diagnostic CT scanners. The details of NPS and NEQ measurement are outlined and special attention is paid to issues unique to multislice CT. Aliasing, filter design and effects of acquisition geometry are investigated. While it was found that both metrics can be implemented in modern CT, it was discovered that NEQ cannot be aptly applied with certain non-traditional reconstruction filters or in helical mode. NPS and NEQ under a variety of conditions are examined. Extensions of NPS and NEQ to uses in protocol standardization are also discussed.

  5. Quantitative planar and volumetric cardiac measurements using 64 MDCT and 3T MRI versus standard 2D and M-mode echocardiography: Does anesthetic protocol matter?

    PubMed Central

    Drees, Randi; Johnson, Rebecca A; Stepien, Rebecca L; Rio, Alejandro Munoz Del; Saunders, Jimmy H; François, Christopher J

    2016-01-01

    Cross-sectional imaging of the heart utilizing computed tomography (CT) and magnetic resonance imaging (MRI) has been shown to be superior for the evaluation of cardiac morphology and systolic function in humans compared to echocardiography. The purpose of this prospective study was to test the effects of two different anesthetic protocols on cardiac measurements in 10 healthy beagle dogs using 64-multidetector row computed tomographic angiography (64-MDCTA), 3T magnetic resonance (MRI) and standard awake echocardiography. Both anesthetic protocols used propofol for induction and isoflourane for anesthetic maintenance. In addition, protocol A used midazolam/fentanyl and protocol B used dexmedetomedine as premedication and constant rate infusion during the procedure. Significant elevations in systolic and mean blood pressure were present when using protocol B. There was overall good agreement between the variables of cardiac size and systolic function generated from the MDCTA and MRI exams and no significant difference was found when comparing the variables acquired using either anesthetic protocol within each modality. Systolic function variables generated using 64-MDCTA and 3T MRI were only able to predict the left ventricular end diastolic volume as measured during awake echocardiogram when using protocol B and 64-MDCTA. For all other systolic function variables, prediction of awake echocardiographic results was not possible (P = 1). Planar variables acquired using MDCTA or MRI did not allow prediction of the corresponding measurements generated using echocardiography in the awake patients (P=1). Future studies are needed to validate this approach in a more varied population and clinically affected dogs. PMID:26082285

  6. Bladder carcinoma: MDCT cystography and virtual cystoscopy.

    PubMed

    Panebianco, Valeria; Sciarra, Alessandro; Di Martino, Michele; Bernardo, Silvia; Vergari, Valeria; Gentilucci, Alessandro; Catalano, Carlo; Passariello, Roberto

    2010-06-01

    Bladder carcinoma is the most common tumor among the low urinary tract, accounting for 90% of cancer cases. Conventional cystoscopy represents the gold standard for diagnosis and local management of bladder carcinoma. As the prevalence of transitional cell carcinoma is four-fold greater in men than in women, the endoscopic procedure presents objective difficulties related to the length and bending of male urethra. The most important problems are represented by intense discomfort for the patient and bleeding; furthermore, the high cost, invasivity, and local complications such as infections and mechanical lesions are well-known drawbacks. Additionally, conventional cystoscopy does not provide information about extravescical extensions of the tumor. CT cystography, combined with virtual cystoscopy, is mandatory for TNM staging of the tumor and also is useful when conventional cystoscopy is inconclusive or cannot be performed. We presents the CT cystography findings with virtual endoscopy correlation and bladder carcinoma appearance.

  7. Cardiac Computed Tomography (Multidetector CT, or MDCT)

    MedlinePlus

    ... Graft (CABG) Surgery Atherosclerosis Coronary Artery Disease (CAD) Heart Attack • Home • About Heart Attacks • Warning Signs of a ... Heart Attack • Heart Attack Tools & Resources • Support Network Heart Attack Tools & Resources What Is a Heart Attack? How ...

  8. Association of abdominal aortic calcium with coronary artery calcium and obstructive coronary artery disease: a pilot study.

    PubMed

    Zweig, Bryan M; Sheth, Meetkumar; Simpson, Steve; Al-Mallah, Mouaz H

    2012-02-01

    This study sought to determine the association of abdominal aortic calcium (AAC) with coronary artery calcium (CAC) and obstructive coronary artery disease (CAD). We included 58 patients (mean age 54.4 years, 40% males) without known CAD who underwent a non-contrast abdominal computed tomography (CT) scan and 64-slice coronary computed tomography angiography (CCTA) within 2 years. A total AAC score using Agatston method was calculated in the abdominal aorta from the takeoff of the celiac artery to the aortic bifurcation. A total of 43/58 patients had AAC. Patients with AAC were older with no differences in other baseline characteristics. None of the patients with a zero AAC score had obstructive CAD. Thus, an AAC score of zero had a 100% negative predictive value (NPV) and 23% positive predictive value (PPV) for the detection of obstructive CAD and an 80% NPV and 79% PPV for detection of any coronary plaque. Using multivariate linear regression, AAC score was an independent predictor of CAC score after adjusting for age (P < 0.001). In our analysis, AAC score correlates with CAC score and has a high NPV to rule out CAD. The absence of AAC may help exclude obstructive coronary disease and improve the selection of patients that may benefit from further risk stratification.

  9. Integrative computed tomographic imaging of cardiac structure, function, perfusion, and viability.

    PubMed

    Thilo, Christian; Hanley, Michael; Bastarrika, Gorka; Ruzsics, Balazs; Schoepf, U Joseph

    2010-01-01

    Recent advances in multidetector-row computed tomography (MDCT) technology have created new opportunities in cardiac imaging and provided new insights into a variety of disease states. Use of 64-slice coronary computed tomography angiography has been validated for the evaluation of clinically relevant coronary artery stenosis with high negative predictive values for ruling out significant obstructive disease. This technology has also advanced the care of patients with acute chest pain by simultaneous assessment of acute coronary syndrome, pulmonary embolism, and acute aortic syndrome ("triple rule out"). Although MDCT has been instrumental in the advancement of cardiac imaging, there are still limitations in patients with high or irregular heart rates. Newer MDCT scanner generations hold promise to improve some of these limitations for noninvasive cardiac imaging. The evaluation of coronary artery stenosis remains the primary clinical indication for cardiac computed tomography angiography. However, the use of MDCT for simultaneous assessment of coronary artery stenosis, atherosclerotic plaque formation, ventricular function, myocardial perfusion, and viability with a single modality is under intense investigation. Recent technical developments hold promise for accomplishing this goal and establishing MDCT as a comprehensive stand-alone test for integrative imaging of coronary heart disease.

  10. Atherosclerotic coronary plaque in subjects with diabetic neuropathy: the prognostic cardiovascular role of Charcot neuroarthropathy--a case-control study.

    PubMed

    Pitocco, D; Marano, R; Di Stasio, E; Scavone, G; Savino, G; Zaccardi, F; Rizzi, A; Martini, F; Musella, T; Silvestri, V; Costantini, F; Galli, M; Caputo, S; Bonomo, L; Ghirlanda, G

    2014-08-01

    The aim of this study was to investigate the severity of coronary artery disease (CAD) and the plaque composition in neuropathic type 2 diabetic subjects with and without Charcot neuroarthropathy (CN) undergoing multidetector computed tomography coronary angiography (MDCT-CA). The study was a single-center, observational, with unmatched case-control design. We selected 17 CN patients and 18 patients with diabetic neuropathy (DN) without CN. In all the patients, multidetector computed tomography was performed to assess the coronary artery calcium score (CACS) and degree of coronary artery stenosis. Patients were classified as positive in the presence of significant CAD if there was at least one stenosis >50 % on MDCT-CA. The invasive coronary angiography was performed in case of significant stenosis detected with MDCT-CA, both as reference to standard and eventually as treatment. Groups were matched for age, sex, and traditional CAD risk factors. As compared to DN individuals, CN exhibited higher rates of significant coronary stenoses (p = 0.027; OR 7.7 [1.3-43.5]). However, no significant differences were observed in the CACS, which reflects plaque burden, in the two groups (p = 0.759). No significant differences were observed comparing CACS distribution in all subjects for stenosis higher/equal or lower than 50 % (p = 0.320). Finally, no significant differences were observed comparing CACS distribution in CN and DN subjects for coronary stenoses higher/equal or lower than 50 %. Our results suggest that CN patients have a higher prevalence of severe coronary plaques compared to DN patients. Nevertheless, coronary plaques in CN patients did not exhibit an increased degree of calcification.

  11. Improving Image Quality of On-Board Cone-Beam CT in Radiation Therapy Using Image Information Provided by Planning Multi-Detector CT: A Phantom Study

    PubMed Central

    Yang, Ching-Ching; Chen, Fong-Lin; Lo, Yeh-Chi

    2016-01-01

    Purpose The aim of this study was to improve the image quality of cone-beam computed tomography (CBCT) mounted on the gantry of a linear accelerator used in radiation therapy based on the image information provided by planning multi-detector CT (MDCT). Methods MDCT-based shading correction for CBCT and virtual monochromatic CT (VMCT) synthesized using the dual-energy method were performed. In VMCT, the high-energy data were obtained from CBCT, while the low-energy data were obtained from MDCT. An electron density phantom was used to investigate the efficacy of shading correction and VMCT on improving the target detectability, Hounsfield unit (HU) accuracy and variation, which were quantified by calculating the contrast-to-noise ratio (CNR), the percent difference (%Diff) and the standard deviation of the CT numbers for tissue equivalent background material, respectively. Treatment plan studies for a chest phantom were conducted to investigate the effects of image quality improvement on dose planning. Results For the electron density phantom, the mean value of CNR was 17.84, 26.78 and 34.31 in CBCT, shading-corrected CBCT and VMCT, respectively. The mean value of %Diff was 152.67%, 11.93% and 7.66% in CBCT, shading-corrected CBCT and VMCT, respectively. The standard deviation within a uniform background of CBCT, shading-corrected CBCT and VMCT was 85, 23 and 15 HU, respectively. With regards to the chest phantom, the monitor unit (MU) difference between the treatment plan calculated using MDCT and those based on CBCT, shading corrected CBCT and VMCT was 6.32%, 1.05% and 0.94%, respectively. Conclusions Enhancement of image quality in on-board CBCT can contribute to daily patient setup and adaptive dose delivery, thus enabling higher confidence in patient treatment accuracy in radiation therapy. Based on our results, VMCT has the highest image quality, followed by the shading corrected CBCT and the original CBCT. The research results presented in this study should be

  12. TU-EF-204-10: A Preliminary Study Evaluating Calculation Variations of Local Noise Power Spectra for CT Simulation in Radiation Therapy

    SciTech Connect

    Dolly, S; Chen, H; Anastasio, M; Mutic, S; Li, H

    2015-06-15

    Purpose: Local noise power spectrum (NPS) properties are significantly affected by calculation variables and CT acquisition and reconstruction parameters, but a thoughtful analysis of these effects is absent. In this study, we performed a complete analysis of the effects of calculation and imaging parameters on the NPS. Methods: The uniformity module of a Catphan phantom was scanned with a Philips Brilliance 64-slice CT simulator using various scanning protocols. Images were reconstructed using both FBP and iDose4 reconstruction algorithms. From these images, local NPS were calculated for regions of interest (ROI) of varying locations and sizes, using four image background removal methods. Additionally, using a predetermined ground truth, NPS calculation accuracy for various calculation parameters was compared for computer simulated ROIs. A complete analysis of the effects of calculation, acquisition, and reconstruction parameters on the NPS was conducted. Results: The local NPS varied with ROI size and image background removal method, particularly at low spatial frequencies. The image subtraction method was the most accurate according to the computer simulation study, and was also the most effective at removing low frequency background components in the acquired data. However, first-order polynomial fitting using residual sum of squares and principle component analysis provided comparable accuracy under certain situations. Similar general trends were observed when comparing the NPS for FBP to that of iDose4 while varying other calculation and scanning parameters. However, while iDose4 reduces the noise magnitude compared to FBP, this reduction is spatial-frequency dependent, further affecting NPS variations at low spatial frequencies. Conclusion: The local NPS varies significantly depending on calculation parameters, image acquisition parameters, and reconstruction techniques. Appropriate local NPS calculation should be performed to capture spatial variations of

  13. Four- and Eight-Channel Aortoiliac CT Angiography: A Comparative Study

    SciTech Connect

    Karcaaltincaba, Musturay Foley, Dennis

    2005-04-15

    Purpose. To compare performance parameters, contrast material load and radiation dose in a patient cohort having aortoiliac CT angiography using 4- and 8-channel multidetector CT (MDCT) systems. Methods. Eighteen patients with abdominal aortic aneurysms underwent initial 4-channel and follow-up 8-channel MDCT angiography. Both the 4- and 8-channel MDCT systems utilized a matrix detector of 16 x 1.25 mm rows. Scan coverage included the abdominal aorta and iliac arteries to the level of the proximal femoral arteries. For 4-channel MDCT, nominal slice thickness and beam pitch were 1.25 mm and 1.5, respectively, and for 8-channel MDCT they were 1.25 mm and 1.35 or 1.65 respectively. Scan duration, iodinated contrast material load and mean aortoiliac attenuation were compared retrospectively. Comparative radiation dose measurements for 4- and 8-channel MDCT were obtained using a multiple scan average dose technique on an abdominal phantom. Results. Compared with 4-channel MDCT, 8-channel MDCT aortoiliac angiography was performed with equivalent collimation, decreased contrast load (mean 45% decrease: 144 ml versus 83 ml of 300 mg iodine/ml contrast material) and decreased acquisition time (mean 51% shorter: 34.4 sec versus 16.9 sec) without a significant change in mean aortic enhancement (299 HU versus 300 HU, p > 0.05). Radiation dose was 2 rad for the 4-channel system and 2/1.5 rad for the 8-channel system at 1.35/1.65 pitch respectively. Conclusion. Compared with 4-channel MDCT, aortoiliac CT angiography with 8-channel MDCT produces equivalent z-axis resolution with decreased contrast load and acquisition time without increased radiation exposure.

  14. Volume estimation of low-contrast lesions with CT: a comparison of performances from a phantom study, simulations and theoretical analysis

    NASA Astrophysics Data System (ADS)

    Li, Qin; Gavrielides, Marios A.; Zeng, Rongping; Myers, Kyle J.; Sahiner, Berkman; Petrick, Nicholas

    2015-01-01

    Measurements of lung nodule volume with multi-detector computed tomography (MDCT) have been shown to be more accurate and precise compared to conventional lower dimensional measurements. Quantifying the size of lesions is potentially more difficult when the object-to-background contrast is low as with lesions in the liver. Physical phantom and simulation studies are often utilized to analyze the bias and variance of lesion size estimates because a ground truth or reference standard can be established. In addition, it may also be useful to derive theoretical bounds as another way of characterizing lesion sizing methods. The goal of this work was to study the performance of a MDCT system for a lesion volume estimation task with object-to-background contrast less than 50 HU, and to understand the relation among performances obtained from phantom study, simulation and theoretical analysis. We performed both phantom and simulation studies, and analyzed the bias and variance of volume measurements estimated by a matched-filter-based estimator. We further corroborated results with a theoretical analysis to estimate the achievable performance bound, which was the Cramer-Rao’s lower bound (CRLB) of minimum variance for the size estimates. Results showed that estimates of non-attached solid small lesion volumes with object-to-background contrast of 31-46 HU can be accurate and precise, with less than 10.8% in percent bias and 4.8% in standard deviation of percent error (SPE), in standard dose scans. These results are consistent with theoretical (CRLB), computational (simulation) and empirical phantom bounds. The difference between the bounds is rather small (for SPE less than 1.9%) indicating that the theoretical- and simulation-based performance bounds can be good surrogates for physical phantom studies.

  15. SU-E-I-27: Estimating KERMA Area Product for CT Localizer Images

    SciTech Connect

    Ogden, K; Greene-Donnelly, K; Bennett, R; Thorpe, M

    2015-06-15

    Purpose: To estimate the free-in-air KERMA-Area Product (KAP) incident on patients due to CT localizer scans for common CT exams. Methods: In-plane beam intensity profiles were measured in localizer acquisition mode using OSLs for a 64 slice MDCT scanner (Lightspeed VCT, GE Medical Systems, Waukesha WI). The z-axis beam width was measured as a function of distance from isocenter. The beam profile and width were used to calculate a weighted average air KERMA per unit mAs as a function of intercepted x-axis beam width for objects symmetric about the localizer centerline.Patient areas were measured using manually drawn regions and divided by localizer length to determine average width. Data were collected for 50 head exams (lateral localizer only), 15 head/neck exams, 50 chest exams, and 50 abdomen/pelvis exams. Mean patient widths and acquisition techniques were used to calculate the weighted average free-in-air KERMA, which was multiplied by the patient area to estimate KAP. Results: Scan technique was 120 kV tube voltage, 10 mA current, and table speed of 10 cm/s. The mean ± standard deviation values of KAP were 120 ± 11.6, 469 ± 62.6, 518 ± 45, and 763 ± 93 mGycm{sup 2} for head, head/neck, chest, and abdomen/pelvis exams, respectively. For studies with AP and lateral localizers, the AP/lateral area ratio was 1.20, 1.33, and 1.24 for the head/neck, chest, and abdomen/pelvis exams, respectively. However, the AP/lateral KAP ratios were 1.12, 1.08, and 1.07, respectively. Conclusion: Calculation of KAP in CT localizers is complicated by the non-uniform intensity profile and z-axis beam width. KAP values are similar to those for simple radiographic exams such as a chest radiograph and represent a small fraction of the x-ray exposure at CT. However, as CT doses are reduced the localizer contribution will be a more significant fraction of the total exposure.

  16. Accuracy in contouring of small and low contrast lesions: Comparison between diagnostic quality computed tomography scanner and computed tomography simulation scanner-A phantom study

    SciTech Connect

    Ho, Yick Wing; Wong, Wing Kei Rebecca; Yu, Siu Ki; Lam, Wai Wang; Geng Hui

    2012-01-01

    To evaluate the accuracy in detection of small and low-contrast regions using a high-definition diagnostic computed tomography (CT) scanner compared with a radiotherapy CT simulation scanner. A custom-made phantom with cylindrical holes of diameters ranging from 2-9 mm was filled with 9 different concentrations of contrast solution. The phantom was scanned using a 16-slice multidetector CT simulation scanner (LightSpeed RT16, General Electric Healthcare, Milwaukee, WI) and a 64-slice high-definition diagnostic CT scanner (Discovery CT750 HD, General Electric Healthcare). The low-contrast regions of interest (ROIs) were delineated automatically upon their full width at half maximum of the CT number profile in Hounsfield units on a treatment planning workstation. Two conformal indexes, CI{sub in}, and CI{sub out}, were calculated to represent the percentage errors of underestimation and overestimation in the automated contours compared with their actual sizes. Summarizing the conformal indexes of different sizes and contrast concentration, the means of CI{sub in} and CI{sub out} for the CT simulation scanner were 33.7% and 60.9%, respectively, and 10.5% and 41.5% were found for the diagnostic CT scanner. The mean differences between the 2 scanners' CI{sub in} and CI{sub out} were shown to be significant with p < 0.001. A descending trend of the index values was observed as the ROI size increases for both scanners, which indicates an improved accuracy when the ROI size increases, whereas no observable trend was found in the contouring accuracy with respect to the contrast levels in this study. Images acquired by the diagnostic CT scanner allow higher accuracy on size estimation compared with the CT simulation scanner in this study. We recommend using a diagnostic CT scanner to scan patients with small lesions (<1 cm in diameter) for radiotherapy treatment planning, especially for those pending for stereotactic radiosurgery in which accurate delineation of small

  17. Bladder trauma: multidetector computed tomography cystography.

    PubMed

    Ishak, Charbel; Kanth, Nalini

    2011-08-01

    Multidetector computed tomography (MDCT) cystography is rapidly becoming the most recommended study for evaluation of the bladder for suspected trauma. This article reviews the bladder trauma with emphasis on the application of MDCT cystography to traumatic bladder injuries using a pictorial essay based on images collected in our level I trauma center.

  18. Cardio-Ankle Vascular Index in a Thai Population

    PubMed Central

    Yingchoncharoen, Teerapat; Sritara, Piyamitr

    2017-01-01

    Arterial stiffness as measured by the cardio-ankle vascular index (CAVI) is a widely available method in Thailand. Data from a large cross-sectional study revealed a significant correlation of CAVI and the presence of coronary artery disease as detected from 64-slice coronary computed tomography arteriography. Futhermore, CAVI was shown to predict long-term cardiovascular events in the patients with intermediate cardiovascular risk.

  19. Comparison of Diagnostic Accuracy of Radiation Dose-Equivalent Radiography, Multidetector Computed Tomography and Cone Beam Computed Tomography for Fractures of Adult Cadaveric Wrists

    PubMed Central

    Neubauer, Jakob; Benndorf, Matthias; Reidelbach, Carolin; Krauß, Tobias; Lampert, Florian; Zajonc, Horst; Kotter, Elmar; Langer, Mathias; Fiebich, Martin; Goerke, Sebastian M.

    2016-01-01

    Purpose To compare the diagnostic accuracy of radiography, to radiography equivalent dose multidetector computed tomography (RED-MDCT) and to radiography equivalent dose cone beam computed tomography (RED-CBCT) for wrist fractures. Methods As study subjects we obtained 10 cadaveric human hands from body donors. Distal radius, distal ulna and carpal bones (n = 100) were artificially fractured in random order in a controlled experimental setting. We performed radiation dose equivalent radiography (settings as in standard clinical care), RED-MDCT in a 320 row MDCT with single shot mode and RED-CBCT in a device dedicated to musculoskeletal imaging. Three raters independently evaluated the resulting images for fractures and the level of confidence for each finding. Gold standard was evaluated by consensus reading of a high-dose MDCT. Results Pooled sensitivity was higher in RED-MDCT with 0.89 and RED-MDCT with 0.81 compared to radiography with 0.54 (P = < .004). No significant differences were detected concerning the modalities’ specificities (with values between P = .98). Raters' confidence was higher in RED-MDCT and RED-CBCT compared to radiography (P < .001). Conclusion The diagnostic accuracy of RED-MDCT and RED-CBCT for wrist fractures proved to be similar and in some parts even higher compared to radiography. Readers are more confident in their reporting with the cross sectional modalities. Dose equivalent cross sectional computed tomography of the wrist could replace plain radiography for fracture diagnosis in the long run. PMID:27788215

  20. Multidetector computed tomography findings in deaths with severe burns.

    PubMed

    Levy, Angela D; Harcke, Howard T; Getz, John M; Mallak, Craig T

    2009-06-01

    This study compared autopsy with postmortem multidetector computed tomography (MDCT) findings in charred remains. Seventeen consecutive male subjects (mean age, 29.4 years) who perished in a fire-related event resulting in charred remains underwent total body MDCT immediately prior to routine autopsy that included serum carboxyhemoglobin measurement. MDCT showed all thermal tissue changes (skin and subcutaneous fat loss, skeletal muscle retraction, pugilistic attitude, cortical fractures, bone and organ destruction, thermal epidural hematoma, and thermal amputation) and established all fracture patterns that were lethal, but autopsy added the fire as a contributory cause of death when there was carboxyhemoglobin elevation. MDCT had limited value in determination of lethal vascular and visceral injuries. MDCT is an effective complement to autopsy in the setting of charred remains and may serve to augment a limited autopsy. This may be particularly useful in mass casualty scenarios.

  1. Clinical significance of multidetector-row computed tomography in breast surgery.

    PubMed

    Doihara, Hiroyoshi; Fujita, Takeo; Takabatake, Daisuke; Takahashi, Hirotoshi; Ogasawara, Yutaka; Shimizu, Nobuyoshi

    2006-01-01

    Several reports support the association of higher ipsilateral breast tumor recurrence rates with positive or intermediate margins compared with negative pathologic margins. Precise evaluation of tumor extension and adequate surgical margin are important factors affecting tumor recurrence after breast-conserving surgery (BCS). Many studies have reported the utility of magnetic resonance imaging (MRI) for diagnosing the tumor extension of breast cancer, but few have evaluated the utility of multidetector-row computed tomography (MDCT). The results of this study show the clinical significance of MDCT for detecting cancer extension and demonstrate the clinical role of MDCT in BCS. Subjects comprised 136 patients grouped into two categories based on whether or not tumor extension was evaluated with MDCT preoperatively. The positive surgical margin rate and breast conservation rate were analyzed in each group and the clinical role of MDCT in BCS was evaluated. Moreover, evaluation of intraductal extension was done both with MDCT and histologically, and computed tomography (CT)-pathologic correlations were examined retrospectively. Finally, the margin-positive cases were analyzed in relation to their clinical characteristics. Sensitivity, specificity, positive predictive value, and negative predictive value for detection of the intraductal component were 71.8%, 85.7%, 82.1%, and 76.9%, respectively. The positive surgical margin rate and conservation rate are 7.46% and 81.9%, respectively, for those who were diagnosed with MDCT preoperatively; their corresponding rates without MDCT were 16.67% and 67.9%. Most margin-positive patients have remarkable lymphatic space invasion. Positive surgical margins were often recognized toward the nipple. For diagnosing the intraductal extension, MDCT shows sufficient diagnosability. Moreover, MDCT can provide appropriate information for the determination of adequate surgical margins and contribute to increases in breast conservation

  2. The utility of gadoxetic acid-enhanced magnetic resonance imaging in the surveillance for postoperative recurrence of hepatocellular carcinoma

    PubMed Central

    Kim, Jung Hee; Min, Yang Won; Gwak, Geum-Youn; Paik, Yong Han; Choi, Moon Seok; Lee, Joon Hyoek; Koh, Kwang Cheol; Paik, Seung Woon

    2016-01-01

    Abstract This study aimed to investigate the utility of gadoxetic acid-enhanced magnetic resonance imaging (Gd-MRI) in surveillance for recurrent hepatocellular carcinoma (HCC) after hepatectomy. This retrospective study analyzed 147 patients who underwent surveillance with alternating multidetector computed tomography (MDCT) and Gd-MRI after hepatectomy for HCC. The patients were followed-up every 3 months during the first 2 years, and every 6 months thereafter. At each visit, MDCT was performed but once a year (every 12 months), Gd-MRI was performed instead of MDCT. Each HCC recurrence detection rate of MDCT and Gd-MRI was evaluated, and recurrent HCC characteristics were compared according to the detection test. A total of 63 patients had recurrent HCC. Among them, 9 were detected with Gd-MRI and 29 with MDCT. The baseline characteristics of patients with recurrent HCC showed no significant differences according to the detection test. The HCC recurrence detection rate of Gd-MRI and MDCT was 4.8% (9/180) and 4.3% (29/580), respectively, on the per test basis (P = 0.764). However, in the population with a follow-up period of ≥12 months, the detection rate of Gd-MRI and MDCT was 4.3% (7/150) and 1.5% (19/400), respectively (P = 0.035). Recurrent HCCs detected with Gd-MRI were smaller than those detected with MDCT (tumor size < 2 cm, 100% vs 65.5%, P = 0.040). Our data suggest that Gd-MRI has advantages in detecting recurrent HCC after hepatectomy. Surveillance with alternating MDCT and Gd-MRI may identify more recurrent HCC in an early stage than with MDCT alone in patients who received hepatectomy for HCC. PMID:28002336

  3. Multidetector-Row Computed Tomography in the Evaluation of Transjugular Intrahepatic Portosystemic Shunt Performed with Expanded-Polytetrafluoroethylene-Covered Stent-Graft

    SciTech Connect

    Fanelli, Fabrizio Bezzi, Mario; Bruni, Antonio; Corona, Mario; Boatta, Emanuele; Lucatelli, Pierleone; Passariello, Roberto

    2011-02-15

    We assessed, in a prospective study, the efficacy of multidetector spiral computed tomography (MDCT) in the evaluation of transjugular intrahepatic portosystemic shunt (TIPS) patency in patients treated with the Viatorr (Gore, Flagstaff, AZ) expanded-polytetrafluoroethylene (e-PTFE)-covered stent-graft. Eighty patients who underwent TIPS procedure using the Viatorr self-expanding e-PTFE stent-graft were evaluated at follow-up of 1, 3, 6, and 12 months with clinical and laboratory tests as well as ultrasound-color Doppler (USCD) imaging. In case of varices, upper gastrointestinal endoscopy was also performed. In addition, the shunt was evaluated using MDCT at 6 and 12 months. In all cases of abnormal findings and discrepancy between MDCT and USCD, invasive control venography was performed. MDCT images were acquired before and after injection of intravenous contrast media on the axial plane and after three-dimensional reconstruction using different algorithms. MDCT was successfully performed in all patients. No artefacts correlated to the Viatorr stent-graft were observed. A missing correlation between UCSD and MDCT was noticed in 20 of 80 (25%) patients. Invasive control venography confirmed shunt patency in 16 (80%) cases and shunt malfunction in 4 (20%) cases. According to these data, MDCT sensitivity was 95.2%; specificity was 96.6%; and positive (PPV) and negative predictive values (NPV) were 90.9 and 98.2%, respectively. USCD sensitivity was 90%; specificity was 75%; and PPV and NPV were 54.5 and 95.7%, respectively. A high correlation (K value = 0.85) between MDCT and invasive control venography was observed. On the basis of these results, MDCT shows superior sensitivity and specificity compared with USCD in those patients in whom TIPS was performed with the Viatorr stent-graft. MDCT can be considered a valid tool in the follow-up of these patients.

  4. A study considering the force required for broken glass bottles to penetrate a skin simulant.

    PubMed

    Nolan, Gary; Lawes, Simon; Hainsworth, Sarah; Rutty, Guy

    2012-01-01

    Injuries and assaults related to alcohol consumption are a growing concern in many countries. In such cases, the use of impulsive weapons, an object from the immediate environment, such as a glass bottle, is not uncommon. This current study utilises a material testing system to measure the force required to push a broken glass bottle into a skin simulant with the displacement of the bottle into the skin simulant being recorded simultaneously, using a linear variable differential transformer (LVDT). From this data, load versus displacement plots were produced. Multi-detector computed tomography (MDCT) was also used to analyse bottle wall thickness to determine if a relationship could be found between force required for penetration and bottle wall thickness. The forces required for the penetration of the skin simulant ranged from 9.8 to 56.7 N. The range was found to be independent of bottle type with the variation in force for penetration being attributed to the varying fracture points, with some fractures presenting a sharper point on first contact with the skin. Although the dangers associated with the use of broken bottles as weapons is apparent, there is a paucity of information in this area in the current English literature, which this study has addressed. The results of this study also highlight the risks of attempting reconstructions of broken bottle stab events.

  5. Support vector machine model for diagnosis of lymph node metastasis in gastric cancer with multidetector computed tomography: a preliminary study

    PubMed Central

    2011-01-01

    Background Lymph node metastasis (LNM) of gastric cancer is an important prognostic factor regarding long-term survival. But several imaging techniques which are commonly used in stomach cannot satisfactorily assess the gastric cancer lymph node status. They can not achieve both high sensitivity and specificity. As a kind of machine-learning methods, Support Vector Machine has the potential to solve this complex issue. Methods The institutional review board approved this retrospective study. 175 consecutive patients with gastric cancer who underwent MDCT before surgery were included. We evaluated the tumor and lymph node indicators on CT images including serosal invasion, tumor classification, tumor maximum diameter, number of lymph nodes, maximum lymph node size and lymph nodes station, which reflected the biological behavior of gastric cancer. Univariate analysis was used to analyze the relationship between the six image indicators with LNM. A SVM model was built with these indicators above as input index. The output index was that lymph node metastasis of the patient was positive or negative. It was confirmed by the surgery and histopathology. A standard machine-learning technique called k-fold cross-validation (5-fold in our study) was used to train and test SVM models. We evaluated the diagnostic capability of the SVM models in lymph node metastasis with the receiver operating characteristic (ROC) curves. And the radiologist classified the lymph node metastasis of patients by using maximum lymph node size on CT images as criterion. We compared the areas under ROC curves (AUC) of the radiologist and SVM models. Results In 175 cases, the cases of lymph node metastasis were 134 and 41 cases were not. The six image indicators all had statistically significant differences between the LNM negative and positive groups. The means of the sensitivity, specificity and AUC of SVM models with 5-fold cross-validation were 88.5%, 78.5% and 0.876, respectively. While the

  6. Multi-detector row CT as a "one-stop" examination in the preoperative evaluation of the morphology and function of living renal donors: preliminary study.

    PubMed

    Su, Chen; Yan, Chaogui; Guo, Yan; Zhou, Xuhui; Chen, Yaqing; Liu, Mingjuan; Wang, Wenjuan; Zhang, Xiaoling

    2011-02-01

    We designed to investigate the feasibility of multi-detector row computerized tomography (CT) as a "one-stop" examination for the simultaneous preoperative evaluation of the morphology and function of living renal donors. 21 living renal donors were examined by 64-slice spiral CT with a three-phase enhancement CT scan and two inserted dynamic scans. The maximum intensity projection (MIP), multi-planar reformation (MPR), and volume reconstruction (VR) procedures were performed to compare the renal parenchyma, renal vessels, and collecting system with operational findings. The known Patlak equation was used to calculate the glomerular filtration rate (GFR); exact GFR information was acquired by single photon emission computed tomography (SPECT). Our results as following, there were 3 cases of artery variation and 3 cases of vein variation. CT findings all corresponded with the operation, and the sensitivity, positive predictive value, specialty, and negative predictive value of CT were all 100%. The r of the GFR values estimated from CT is 0.894 (left) (P < 0.001) and 0.881 (right) (P < 0.001). In conclusions, our findings demonstrate that 64-slice spiral CT may offer a "one-stop" examination to replace SPECT in the preoperative evaluation of living renal donors to simultaneously provide information regarding both anatomy and the GFR of living renal donors.

  7. Iodine-125 Seeds Strand for Treatment of Tumor Thrombus in Inferior Vena Cava: An Experimental Study in a Rabbit Model

    SciTech Connect

    Zhang, Wen Yan, Zhiping Luo, Jianjun Fang, Zhuting Wu, Linlin Liu, QingXin Qu, Xudong Liu, Lingxiao Wang, Jianhua

    2013-10-15

    Objective: The purpose of this study was to establish an animal model of implanted inferior vena cava tumor thrombus (IVCTT) and to evaluate the effect of linear iodine-125 seeds strand in treating implanted IVCTT. Methods: Tumor cell line VX{sub 2} was inoculated subcutaneously into New Zealand rabbit to develop the parent tumor. The tumor strip was inoculated into inferior vena cava (IVC) to establish the IVCTT model. The IVCTT was confirmed by multidetector computed tomography (MDCT) after 2 weeks. Twelve rabbits with IVCTT were randomly divided into two groups. Treatment group (group T; n = 6) underwent Iodine-125 seeds brachytherapy, and the control group (group C; n = 6) underwent blank seeds strand. The blood laboratory examination (including blood routine examination, hepatic and renal function), body weight, survival time, and IVCTT volume by MDCT were monitored. All rabbits were dissected postmortem, and the therapeutic effects were evaluated on the basis of histopathology. The proliferating cell nuclear antigen index (PI) and apoptosis index (AI) of IVCTT were compared between two groups. T test, Wilcoxon rank test, and Kaplan-Meier survival curve analysis were used. Results: The success rate of establishing IVCTT was 100 %. The body weight loss and cachexia of rabbits in group C appeared earlier than in group T. Body weight in the third week, the mean survival time, PI, AI in groups T and C were 2.23 {+-} 0.12 kg, 57.83 {+-} 8.68 days, (16.73 {+-} 5.18 %), (29.47 {+-} 7.18 %), and 2.03 {+-} 0.13 kg, 43.67 {+-} 5.28 days, (63.01 {+-} 2.01 %), (6.02 {+-} 2.93 %), respectively. There were statistically significant differences between group T and group C (P < 0.05). The IVCTT volume of group T was remarkably smaller than that of group C. Conclusions: Injecting and suspensory fixing VX2 tumor strip into IVC is a reliable method to establish IVCTT animal model. The linear Iodine-125 seeds strand brachytherapy was a safe and effective method for treating IVCTT

  8. Characterization of trabecular bone plate-rod microarchitecture using multirow detector CT and the tensor scale: Algorithms, validation, and applications to pilot human studies

    PubMed Central

    Saha, Punam K.; Liu, Yinxiao; Chen, Cheng; Jin, Dakai; Letuchy, Elena M.; Xu, Ziyue; Amelon, Ryan E.; Burns, Trudy L.; Torner, James C.; Levy, Steven M.; Calarge, Chadi A.

    2015-01-01

    Purpose: Osteoporosis is a common bone disease associated with increased risk of low-trauma fractures leading to substantial morbidity, mortality, and financial costs. Clinically, osteoporosis is defined by low bone mineral density (BMD); however, increasing evidence suggests that trabecular bone (TB) microarchitectural quality is an important determinant of bone strength and fracture risk. A tensor scale based algorithm for in vivo characterization of TB plate-rod microarchitecture at the distal tibia using multirow detector CT (MD-CT) imaging is presented and its performance and applications are examined. Methods: The tensor scale characterizes individual TB on the continuum between a perfect plate and a perfect rod and computes their orientation using optimal ellipsoidal representation of local structures. The accuracy of the method was evaluated using computer-generated phantom images at a resolution and signal-to-noise ratio achievable in vivo. The robustness of the method was examined in terms of stability across a wide range of voxel sizes, repeat scan reproducibility, and correlation between TB measures derived by imaging human ankle specimens under ex vivo and in vivo conditions. Finally, the application of the method was evaluated in pilot human studies involving healthy young-adult volunteers (age: 19 to 21 yr; 51 females and 46 males) and patients treated with selective serotonin reuptake inhibitors (SSRIs) (age: 19 to 21 yr; six males and six females). Results: An error of (3.2% ± 2.0%) (mean ± SD), computed as deviation from known measures of TB plate-width, was observed for computer-generated phantoms. An intraclass correlation coefficient of 0.95 was observed for tensor scale TB measures in repeat MD-CT scans where the measures were averaged over a small volume of interest of 1.05 mm diameter with limited smoothing effects. The method was found to be highly stable at different voxel sizes with an error of (2.29% ± 1.56%) at an in vivo voxel size

  9. Usefulness of 40-slice multidetector row computed tomography to detect coronary disease in patients prior to cardiac valve surgery.

    PubMed

    Pouleur, Anne-Catherine; le Polain de Waroux, Jean-Benoît; Kefer, Joëlle; Pasquet, Agnès; Coche, Emmanuel; Vanoverschelde, Jean-Louis; Gerber, Bernhard L

    2007-12-01

    Preoperative identification of significant coronary artery disease (CAD) in patients prior to valve surgery requires systematic invasive coronary angiography. The purpose of this current prospective study was to evaluate whether exclusion of CAD by multi-detector CT (MDCT) might potentially avoid systematic cardiac catheterization in these patients. Eighty-two patients (53 males, 62 +/- 13 years) scheduled to undergo valve surgery underwent 40-slice MDCT before invasive quantitative coronary angiography (QCA). According to QCA, 15 patients had CAD (5 one-vessel, 6 two-vessel and 4 three-vessel disease). The remaining 67 patients had no CAD. On a per-vessel basis, MDCT correctly identified 27/29 (sensitivity 93%) vessels with and excluded 277/299 vessels (specificity 93%) without CAD. On a per-patient basis, MDCT correctly identified 14/15 patients with (sensitivity 93%) and 60/67 patients without CAD (specificity 90%). Positive and negative predictive values of MDCT were 67% and 98%. Performing invasive angiography only in patients with abnormal MDCT might have avoided QCA in 60/82 (73%). MDCT could be potentially useful in the preoperative evaluation of patients with valve disease. By selecting only those patients with coronary lesions to undergo invasive coronary angiography, it could avoid cardiac catheterization in a large number of patients without CAD.

  10. Does Computed Tomography Change our Observation and Management of Fracture Non-Unions?

    PubMed Central

    Kleinlugtenbelt, Ydo V.; Scholtes, Vanessa A.B.; Toor, Jay; Amaechi, Christian; Maas, Mario; Bhandari, Mohit; Poolman, Rudolf W.; Kloen, Peter

    2016-01-01

    Background: The purpose of this study was to determine whether Multi-Detector Computed Tomography (MDCT) in addition to plain radiographs influences radiologists’ and orthopedic surgeons’ diagnosis and treatment plans for delayed unions and non-unions. Methods: A retrospective database of 32 non-unions was reviewed by 20 observers. On a scale of 1 to 5, observers rated on X-Ray and a subsequent Multi Detector Helical Computer Tomography (MDCT) scan was performed to determine the following categories: “healed”, “bridging callus present”, “persistent fracture line” or “surgery advised”. Interobserver reliability in each category was calculated using the Interclass Correlation Coefficient (ICC). The influence of the MDCT scan on the raters’ observations was determined in each case by subtracting the two scores of both time points. Results: All four categories show fair interobserver reliability when using plain radiographs. MDCT showed no improvement, the reliability was poor for the categories “bridging callus present” and “persistent fracture line”, and fair for “healed” and “surgery advised”. In none of the cases, MDCT led to a change of management from nonoperative to operative treatment or vice versa. For 18 out of 32 cases, the treatment plans did not alter. In seven cases MDCT led to operative treatment while on X-ray the treatment plan was undecided. Conclusion: In this study, the interobserver reliability of MDCT scan is not greater than conventional radiographs for determining non-union. However, a MDCT scan did lead to a more invasive approach in equivocal cases. Therefore a MDCT is only recommended for making treatment strategies in those cases. PMID:27847846

  11. A novel biomarker of coronary atherosclerosis: serum DKK1 concentration correlates with coronary artery calcification and atherosclerotic plaques.

    PubMed

    Kim, Kwang-Il; Park, Kyoung Un; Chun, Eun Ju; Choi, Sang Il; Cho, Young-Seok; Youn, Tae-Jin; Cho, Goo-Yeong; Chae, In-Ho; Song, Junghan; Choi, Dong-Ju; Kim, Cheol-Ho

    2011-09-01

    DKK1 modulates Wnt signaling, which is involved in the atherosclerosis. However, no data exist regarding the usefulness of measuring serum DKK1 concentration in predicting coronary atherosclerosis. A total of 270 consecutive patients (62.8 ± 11.2 yr; 70% male) were included. A contrast-enhanced 64-slice coronary MDCT was performed to identify the presence of atherosclerotic plaques. Agatston calcium scores (CS) were calculated to quantify the coronary artery calcification (CAC). DKK1 concentrations were measured by enzyme-linked immunosorbent assay. For each subsequent DKK1 quartile, there was a significant increase in CAC (P = 0.004) and the number of segments with coronary atherosclerosis (P < 0.001). In addition, DKK1 concentration was significantly higher in patients with atherosclerotic plaques, regardless of plaque composition (P = 0.01). Multivariate analysis identified DKK1 as an independent risk factor for the presence of coronary atherosclerotic plaque. The adjusted odds ratio for coronary atherosclerotic plaque was 4.88 (95% CI, 1.67 to 14.25) for highest versus lowest quartile of the DKK1 levels. Furthermore, patients with DKK1 concentrations ≥ 68.6 pg/mL demonstrated coronary atherosclerotic plaques even when they had low CS. Serum DKK1 concentrations correlate with the coronary atherosclerosis and play an independent role in predicting the presence of coronary atherosclerosis.

  12. Focused assessment with sonography for trauma (FAST) versus multidetector computed tomography in hemodynamically stable emergency patients.

    PubMed

    Fornell Pérez, R

    2017-02-10

    This critically appraised topic (CAT) study aims to evaluate the quality and extent of the scientific evidence that supports the use of focused assessment with sonography for trauma (FAST) versus multidetector computed tomography (MDCT) in hemodynamically stable trauma patients in the emergency room. An efficient search of the literature yielded several recent articles with a high level of evidence. The CAT study concludes that FAST is an acceptable initial imaging test in hemodynamically stable patients, although its performance is limited in certain circumstances. The decision whether to use MDCT should be determined by evaluating the patient's degree of instability and the distance to the MDCT scanner. Nevertheless, few articles address the question of the distance to MDCT scanners in emergency departments.

  13. Evaluation of Lung MDCT Nodule Annotation Across Radiologists and Methods1

    PubMed Central

    Meyer, Charles R.; Johnson, Timothy D.; McLennan, Geoffrey; Aberle, Denise R.; Kazerooni, Ella A.; MacMahon, Heber; Mullan, Brian F.; Yankelevitz, David F.; van Beek, Edwin J. R.; Armato, Samuel G.; McNitt-Gray, Michael F.; Reeves, Anthony P.; Gur, David; Henschke, Claudia I.; Hoffman, Eric A.; Bland, Peyton H.; Laderach, Gary; Pais, Richie; Qing, David; Piker, Chris; Guo, Junfeng; Starkey, Adam; Max, Daniel; Croft, Barbara Y.; Clarke, Laurence P.

    2007-01-01

    Rationale and Objectives Integral to the mission of the National Institutes of Health–sponsored Lung Imaging Database Consortium is the accurate definition of the spatial location of pulmonary nodules. Because the majority of small lung nodules are not resected, a reference standard from histopathology is generally unavailable. Thus assessing the source of variability in defining the spatial location of lung nodules by expert radiologists using different software tools as an alternative form of truth is necessary. Materials and Methods The relative differences in performance of six radiologists each applying three annotation methods to the task of defining the spatial extent of 23 different lung nodules were evaluated. The variability of radiologists’ spatial definitions for a nodule was measured using both volumes and probability maps (p-map). Results were analyzed using a linear mixed-effects model that included nested random effects. Results Across the combination of all nodules, volume and p-map model parameters were found to be significant at P < .05 for all methods, all radiologists, and all second-order interactions except one. The radiologist and methods variables accounted for 15% and 3.5% of the total p-map variance, respectively, and 40.4% and 31.1% of the total volume variance, respectively. Conclusion Radiologists represent the major source of variance as compared with drawing tools independent of drawing metric used. Although the random noise component is larger for the p-map analysis than for volume estimation, the p-map analysis appears to have more power to detect differences in radiologist-method combinations. The standard deviation of the volume measurement task appears to be proportional to nodule volume. PMID:16979075

  14. MDCT of pelvic inflammatory disease: a review of the pathophysiology, gamut of imaging findings, and treatment.

    PubMed

    Spain, James; Rheinboldt, Matthew

    2017-02-01

    Representing an ascending, sexually spread pyogenic infection of the female genital tract, pelvic inflammatory disease (PID) is a commonly encountered cause for emergency visits and hospitalizations among young and adult female patients. Though gynecologic evaluation and sonography constitute the mainstay of diagnosis, multidetector CT imaging of the abdomen and pelvis is not uncommonly performed, often as the initial imaging modality, due to the frequently vague and indeterminate clinical presentation. As such, knowledge and attenuation to the often subtle early imaging features of PID afford the radiologist a critical chance to direct and expedite appropriate pathways of patient care, minimizing the risk for secondary complications, including infertility, ectopic pregnancy, and enteric adhesions. In this paper, we will review the pathophysiology, clinical presentation, early and late imaging features of PID as well as potential secondary complications and treatment options. Additionally, we will discuss published data metrics on CT performance regarding sensitivity and specificity for diagnosis as well as potential imaging differential diagnostic considerations.

  15. Defining vascular signatures of malignant hepatic masses: role of MDCT with 3D rendering.

    PubMed

    Ahmed, Sameer; Johnson, Pamela T; Fishman, Elliot K

    2013-08-01

    Malignant hepatic masses, both primary and metastatic lesions, have characteristic CT appearances and enhancement patterns. Owing to advances in CT resolution, high-quality vascular maps can be generated with 3D rendering tools to aid hepatic mass evaluation. These renderings enable identification of neovascularity, which is critical for distinguishing malignant from benign lesions, and facilitate identification of small hyperenhancing malignant hepatic tumors. In this review, CT features of malignant hepatic masses are discussed in conjunction with a demonstration of the role for 3D vascular mapping.

  16. Interrupted Aortic Arch Associated with Absence of Left Common Carotid Artery: Imaging with MDCT

    SciTech Connect

    Onbas, Omer Olgun, Hasim; Ceviz, Naci; Ors, Rahmi; Okur, Adnan

    2006-06-15

    Interrupted aortic arch (IAA) is a rare severe congenital heart defect defined as complete luminal and anatomic discontinuity between ascending and descending aorta. Although its association with various congenital heart defects has been reported, absence of left common carotid artery (CCA) in patients with IAA has not been reported previously. We report a case of IAA associated with the absence of left CCA which was clearly shown on multidetector-row spiral CT.

  17. Congenital solitary kidney with multiple renal arteries: case report using MDCT angiography.

    PubMed

    Matusz, Petru; Miclăuş, Graţian Dragoslav; Banciu, Christian Dragoş; Sas, Ioan; Joseph, Shamfa C; Pirtea, Laurenţiu Cornel; Tubbs, R Shane; Loukas, Marios

    2015-01-01

    A congenital solitary kidney with multiple renal arteries is a rare congenital abnormality that can occur in the presence of multiple other anomalies. We describe an atypical case of a right congenital solitary kidney with three renal arteries (RA) one main RA and two additional renal arteries in a 75-year-old woman with uterine didelphys. The main RA had an intraluminal diameter larger than the diameter of the additional renal arteries (AdRAs) at the origin (0.53 cm for the main RA; 0.49 cm and 0.32 cm for the two AdRAs). Both the AdRAs had a greater length than the main RA (3.51 cm for the main RA; 3.70 cm and 4.77 cm for the two AdRAs). The calculated volume of the kidney was 283 cm³, while the volume of the renal parenchyma was 258 cm³. Knowledge of this variant is extremely important in clinical practice as it has been found to be associated with proteinuria, hypertension and renal insufficiency.

  18. Criteria for establishing shielding of multi-detector computed tomography (MDCT) rooms.

    PubMed

    Verdun, F R; Aroua, A; Baechler, S; Schmidt, S; Trueb, P R; Bochud, F O

    2010-01-01

    The aim of this work is to compare two methods used for determining the proper shielding of computed tomography (CT) rooms while considering recent technological advances in CT scanners. The approaches of the German Institute for Standardisation and the US National Council on Radiation Protection and Measurements were compared and a series of radiation measurements were performed in several CT rooms at the Lausanne University Hospital. The following three-step procedure is proposed for assuring sufficient shielding of rooms hosting new CT units with spiral mode acquisition and various X-ray beam collimation widths: (1) calculate the ambient equivalent dose for a representative average weekly dose length product at the position where shielding is required; (2) from the maximum permissible weekly dose at the location of interest, calculate the transmission factor F that must be taken to ensure proper shielding and (3) convert the transmission factor into a thickness of lead shielding. A similar approach could be adopted to use when designing shielding for fluoroscopy rooms, where the basic quantity would be the dose area product instead of the load of current (milliampere-minute).

  19. Computerized detection of diffuse lung disease in MDCT: the usefulness of statistical texture features

    NASA Astrophysics Data System (ADS)

    Wang, Jiahui; Li, Feng; Doi, Kunio; Li, Qiang

    2009-11-01

    Accurate detection of diffuse lung disease is an important step for computerized diagnosis and quantification of this disease. It is also a difficult clinical task for radiologists. We developed a computerized scheme to assist radiologists in the detection of diffuse lung disease in multi-detector computed tomography (CT). Two radiologists selected 31 normal and 37 abnormal CT scans with ground glass opacity, reticular, honeycombing and nodular disease patterns based on clinical reports. The abnormal cases in our database must contain at least an abnormal area with a severity of moderate or severe level that was subjectively rated by the radiologists. Because statistical texture features may lack the power to distinguish a nodular pattern from a normal pattern, the abnormal cases that contain only a nodular pattern were excluded. The areas that included specific abnormal patterns in the selected CT images were then delineated as reference standards by an expert chest radiologist. The lungs were first segmented in each slice by use of a thresholding technique, and then divided into contiguous volumes of interest (VOIs) with a 64 × 64 × 64 matrix size. For each VOI, we determined and employed statistical texture features, such as run-length and co-occurrence matrix features, to distinguish abnormal from normal lung parenchyma. In particular, we developed new run-length texture features with clear physical meanings to considerably improve the accuracy of our detection scheme. A quadratic classifier was employed for distinguishing between normal and abnormal VOIs by the use of a leave-one-case-out validation scheme. A rule-based criterion was employed to further determine whether a case was normal or abnormal. We investigated the impact of new and conventional texture features, VOI size and the dimensionality for regions of interest on detecting diffuse lung disease. When we employed new texture features for 3D VOIs of 64 × 64 × 64 voxels, our system achieved the highest performance level: a sensitivity of 86% and a specificity of 90% for the detection of abnormal VOIs, and a sensitivity of 89% and a specificity of 90% for the detection of abnormal cases. Our computerized scheme would be useful for assisting radiologists in the diagnosis of diffuse lung disease.

  20. Controversies about effects of low-kilovoltage MDCT acquisition on Agatston calcium scoring.

    PubMed

    Deprez, Fabrice C; Vlassenbroek, Alain; Ghaye, Benoît; Raaijmakers, Rolf; Coche, Emmanuel

    2013-01-01

    Recent articles have advocated the possibility of obtaining Agatston coronary calcium scoring at 100 kVp by using a single adapted elevated calcium threshold. To evaluate the influence of kilovoltage potential protocols on the Agatston score, we acquired successive scans of a calcium scoring phantom at 4 levels of kilovoltage potential (80, 100, 120, and 140 kVp, 55 mAs) and measured semiautomatically the individual and the total Agatston score of 6 inserts (of 5-mm and 3-mm diameter) containing hydroxyapatite at different concentrations (800, 400, 200 mg/cm(3)). Our results showed that Agatston scores obtained at various low-kilovoltage potential protocols can be highly overestimated in some particular cases. At 80 kVp, for example, mean measured Agatston score was multiplied by a factor from 1.06 (5-mm highest density insert) to 2.67 (3-mm lowest density insert) compared with the Agatston scores performed at 120 kVp. Indeed in the one hand, reducing kilovoltage potential in multidetector CT acquisitions increase the CT density of coronary calcifications that can be measured on the reconstructed images. On the other hand, Agatston score is a multi-threshold measurement (with a step weighting function). Consequently low kilovoltage potential can lead to overweight some calcifications scores. For these reasons, Agatston score with low kilovoltage potential acquisition cannot be reliably adapted by a unique recalibration of the standard calcium attenuation threshold of 130 HU and requires a standardized CT acquisition protocol at 120 kVp. Alternatives to performing low-dose coronary artery calcium scans are either using coronary calcium scans with reduced tube current (low mAs) at 120 kVp with the iterative reconstructions or using mass/volume scoring (not influenced by kilovoltage potential variations). Finally, we emphasized that incorrect Agatston score evaluation may have important clinical, financial, and health care implications.

  1. Small bowel obstruction in the emergency department: MDCT features of common and uncommon causes.

    PubMed

    Tirumani, Harika; Vassa, Ravi; Fasih, Najla; Ojili, Vijayanadh

    2014-01-01

    Small bowel obstruction is a common condition encountered by the radiologist in the emergency department. Though intestinal adhesions and obstructed hernias are the most common causes of acute small bowel obstruction, a variety of uncommon and rare conditions can cause acute and subacute bowel obstruction. Imaging plays a key role in the workup of bowel obstruction by identifying the cause, level, and degree of bowel obstruction. In this article, we present a comprehensive review of the multi-detector computed tomography features of common and uncommon causes of acute and subacute small bowel obstruction.

  2. Preoperative evaluation value of aortic arch lesions by multidetector computed tomography angiography in type A aortic dissection

    PubMed Central

    Huang, Fang; Chen, Qiang; Lai, Qing-quan; Huang, Wen-han; Wu, Hong; Li, Wei-cheng

    2016-01-01

    Abstract The purpose of this study was to preoperatively evaluate the value of aortic arch lesions by multidetector computed tomography (MDCT) angiography in type A aortic dissection (AD). From January 2013 to December 2015, we enrolled 42 patients with type A AD who underwent MDCT angiography in our hospital. The institutional database of patients was retrospectively reviewed to identify MDCT angiography examinations for type A AD. Surgical corrections were conducted in all patients to confirm diagnostic accuracy. In this study, the diagnostic accuracy of MDCT angiography was 100% in all 42 patients. The intimal tear site locations that were identified in patients included the ascending aorta (n = 25), aortic arch (n = 12), and all other sites (n = 5). Compared with the control group, there were significant differences in the aortic arch anatomy among the cases. Regarding the distance between the left common carotid and left subclavian arteries, compared with the control group, most cases with type A AD had a significant variation. MDCT angiography plays an important role in detecting aortic arch lesions of type A AD, especially in determining the location of the intimal entry site and change of branch blood vessels. Surgeons can formulate an appropriate operating plan, according to the preoperative MDCT diagnosis information. PMID:27684852

  3. Value and Accuracy of Multidetector Computed Tomography in Obstructive Jaundice

    PubMed Central

    Mathew, Rishi Philip; Moorkath, Abdunnisar; Basti, Ram Shenoy; Suresh, Hadihally B.

    2016-01-01

    Summary Background Objective; To find out the role of MDCT in the evaluation of obstructive jaundice with respect to the cause and level of the obstruction, and its accuracy. To identify the advantages of MDCT with respect to other imaging modalities. To correlate MDCT findings with histopathology/surgical findings/Endoscopic Retrograde CholangioPancreatography (ERCP) findings as applicable. Material/Methods This was a prospective study conducted over a period of one year from August 2014 to August 2015. Data were collected from 50 patients with clinically suspected obstructive jaundice. CT findings were correlated with histopathology/surgical findings/ERCP findings as applicable. Results Among the 50 people studied, males and females were equal in number, and the majority belonged to the 41–60 year age group. The major cause for obstructive jaundice was choledocholithiasis. MDCT with reformatting techniques was very accurate in picking a mass as the cause for biliary obstruction and was able to differentiate a benign mass from a malignant one with high accuracy. There was 100% correlation between the CT diagnosis and the final diagnosis regarding the level and type of obstruction. MDCT was able to determine the cause of obstruction with an accuracy of 96%. Conclusions MDCT with good reformatting techniques has excellent accuracy in the evaluation of obstructive jaundice with regards to the level and cause of obstruction. PMID:27429673

  4. Comparison between blinded and partially blinded detection of gastric cancer with multidetector CT using surgery and endoscopic submucosal dissection as reference standards.

    PubMed

    Kim, H J; Lee, D H; Ko, Y T

    2010-08-01

    The aim of this study is to compare blinded with partially blinded detection of gastric cancer with multidetector (MD) CT by using surgery and endoscopic submucosal dissection (ESD) as reference standards. 44 patients with gastric cancer underwent MDCT with air as an oral contrast agent. Surgery was performed on 37 patients, ESD on six and surgery after ESD on one. To provide comparison cases of blinded evaluation, 38 MDCT examinations were added for cases where no focal gastric lesion was seen on endoscopy. Two radiologists, blinded to the presence, number and location of the tumours, evaluated axial and axial plus multiplanar reformation (MPR) images of 82 MDCT examinations with or without gastric cancer. For partially blinded evaluation, the same radiologists, blinded to the location and number of tumours, evaluated axial and axial plus MPR images of 44 MDCT examinations of gastric cancer. Differences in assessment were resolved by consensus. 45 gastric cancers were found in surgical and ESD specimens. Detection rates of gastric cancer from axial and axial plus MPR images during blinded evaluation and from axial and axial plus MPR images during partially blinded evaluation were 62% (28/45), 64% (29/45), 64% (29/45) and 71% (32/45), respectively. There was no statistical significance for the comparison between blinded and partially blinded detection rates of gastric cancer. The detection rate of gastric cancer with MDCT during blinded evaluation showed no specific difference compared with the detection rate of gastric cancer with MDCT during partially blinded evaluation.

  5. Diagnostic accuracy of 16-slice multidetector-row CT for detection of in-stent restenosis vs detection of stenosis in nonstented coronary arteries.

    PubMed

    Kefer, Joelle M; Coche, Emmanuel; Vanoverschelde, Jean-Louis J; Gerber, Bernhard L

    2007-01-01

    The purpose of this study was to assess the diagnostic accuracy of 16-slice multidetector-row computed tomography (MDCT) for detecting in-stent restenosis. Fifty patients with 69 previously implanted coronary stents underwent 16-slice MDCT before quantitative coronary angiography (QCA). Diagnostic accuracy of MDCT for detection of in-stent restenosis defined as >50% lumen diameter stenosis (DS) in stented and nonstented coronary segments >1.5-mm diameter was computed using QCA as reference. According to QCA, 18/69 (25%) stented segments had restenosis. In addition, 33/518 (6.4%) nonstented segments had >50% DS. In-stent restenosis was correctly identified on MDCT images in 12/18 stents, and absence of restenosis was correctly identified in 50/51 stents. Stenosis in native coronary arteries was correctly identified in 22/33 segments and correctly excluded in 482/485 segments. Thus, sensitivity (67% vs 67% p=1.0), specificity (98% vs 99%, p=0.96) and overall diagnostic accuracy (90% vs 97%, p=0.68) was similarly high for detecting in-stent restenosis as for detecting stenosis in nonstented coronary segments. MDCT has similarly high diagnostic accuracy for detecting in-stent restenosis as for detecting coronary artery disease in nonstented segments. This suggests that MDCT could be clinically useful for identification of restenosis in patients after coronary stenting.

  6. Multidetector computed tomography analysis of benign and malignant nodules in patients with chronic lymphocytic thyroiditis.

    PubMed

    Zhu, Caisong; Liu, Wei; Yang, Jun; Yang, Jing; Shao, Kangwei; Yuan, Lixin; Chen, Hairong; Lu, Wei; Zhu, Ying

    2016-07-01

    The aim of the present study was to compare the multidetector computed tomography (MDCT) features of benign and malignant nodules in patients with chronic lymphocytic thyroiditis (CLT). MDCT findings, including the size, solid percentage, calcification, margin, capsule, anteroposterior-transverse diameter ratio as well as the mode and the degree of enhancement of 137 thyroid nodules in 127 CLT cases were retrospectively analyzed. Furthermore, the correlation between MDCT findings and pathological results combined with the CT perfusion imaging was analyzed for the differences between benign and malignant nodules. A total of 77.5% (31/40) of malignant nodules were completely solid, and 33% (32/97) of benign nodules were predominantly cystic. Compared with the benign nodules, micro-calcification and internal calcification were more frequently observed in the malignant nodules (P<0.05). MDCT features such as ill-defined margin, absence of capsule or incomplete capsule or homogeneous enhancement were more likely to be present in the malignant nodules (P<0.05). Nevertheless, no significant difference was observed in the enhancement degree at arterial or venous phase between benign and malignant nodules (P>0.05). MDCT features are useful in differentiating the benign and malignant nodules in CLT patients, and it may be essential for a radiologist to review the MDCT characteristics of nodules in the clinical practice.

  7. Comparison of Two Accelerators for Monte Carlo Radiation Transport Calculations, NVIDIA Tesla M2090 GPU and Intel Xeon Phi 5110p Coprocessor: A Case Study for X-ray CT Imaging Dose Calculation

    NASA Astrophysics Data System (ADS)

    Liu, Tianyu; Xu, X. George; Carothers, Christopher D.

    2014-06-01

    Hardware accelerators are currently becoming increasingly important in boosting high performance computing sys- tems. In this study, we tested the performance of two accelerator models, NVIDIA Tesla M2090 GPU and Intel Xeon Phi 5110p coprocessor, using a new Monte Carlo photon transport package called ARCHER-CT we have developed for fast CT imaging dose calculation. The package contains three code variants, ARCHER - CTCPU, ARCHER - CTGPU and ARCHER - CTCOP to run in parallel on the multi-core CPU, GPU and coprocessor architectures respectively. A detailed GE LightSpeed Multi-Detector Computed Tomography (MDCT) scanner model and a family of voxel patient phantoms were included in the code to calculate absorbed dose to radiosensitive organs under specified scan protocols. The results from ARCHER agreed well with those from the production code Monte Carlo N-Particle eXtended (MCNPX). It was found that all the code variants were significantly faster than the parallel MCNPX running on 12 MPI processes, and that the GPU and coprocessor performed equally well, being 2.89~4.49 and 3.01~3.23 times faster than the parallel ARCHER - CTCPU running with 12 hyperthreads.

  8. Incidence of Venous Thromboembolism in Patients Undergoing Major Hip Surgeries at a Single Institution: A Prospective Study

    PubMed Central

    Yamanaka, Yasuhiro; Ito, Hiroshi

    2016-01-01

    Background: Venous thoromboembolism (VTE) is one of the most significant complications after hip surgeries. Many studies have been reported about the incidence of VTE after THA, but a small number of reports were found concerning Periacetabular osteotomy, Revision THA and Surgery for hip fracture postoperatively. Furthermore, there exists no comparative study of the incidence of VTE among major hip surgeries at a single institution. We reported the incidence of VTE among hip surgeries performed at a single institution. Methods: A total of 820 Hip surgeries were performed at same institution. The procedures included 420 hips that underwent primary total hip arthroplasties (THA), 91 revision or removal of total hip arthroplasties (Revision THA), 144 periacetabular osteotomy (PAO) and 165 surgery for hip fracture (SHF) between 2006 and 2012. VTE was detected by Multidetector computed tomography (MDCT) that scanned 768 cases and by ultrasound that scanned 52cases postoperative 10-14 days. Results: The overall incidence of VTE was 12.2% (100 of 820). The incidence of VTE after THA was 13.1% (55 of 420), Revision THA was 13.2% (12 of 91), PAO was 2.1% (3 of 144) and SHF was 18.1% (30 of 165). The incidence of VTE was significantly higher in SHF than in PAO. Conclusion: This data indicates that the incidence of VTE after PAO is significantly lower than SHF and relatively lower than THA and Revision THA. A younger age and non-invasion of the bone marrow of the femur may have affected the result. Prophylaxis therapy was effective especially on SHF. PMID:27499823

  9. Multidetector computed tomography in the evaluation of pediatric acute abdominal pain in the emergency department.

    PubMed

    Lin, Wei-Ching; Lin, Chien-Heng

    2016-06-01

    The accurate diagnosis of pediatric acute abdominal pain is one of the most challenging tasks in the emergency department (ED) due to its unclear clinical presentation and non-specific findings in physical examinations, laboratory data, and plain radiographs. The objective of this study was to evaluate the impact of abdominal multidetector computed tomography (MDCT) performed in the ED on pediatric patients presenting with acute abdominal pain. A retrospective chart review of children aged <18 years with acute abdominal pain who visited the emergency department and underwent MDCT between September 2004 and June 2007 was conducted. Patients with a history of trauma were excluded. A total of 156 patients with acute abdominal pain (85 males and 71 females, age 1-17 years; mean age 10.9 ± 4.6 years) who underwent abdominal MDCT in the pediatric ED during this 3-year period were enrolled in the study. One hundred and eighteen patients with suspected appendicitis underwent abdominal MDCT. Sixty four (54.2%) of them had appendicitis, which was proven by histopathology. The sensitivity of abdominal MDCT for appendicitis was found to be 98.5% and the specificity was 84.9%. In this study, the other two common causes of nontraumatic abdominal emergencies were gastrointestinal tract (GI) infections and ovarian cysts. The most common etiology of abdominal pain in children that requires imaging with abdominal MDCT is appendicitis. MDCT has become a preferred and invaluable imaging modality in evaluating uncertain cases of pediatric acute abdominal pain in ED, in particular for suspected appendicitis, neoplasms, and gastrointestinal abnormalities.

  10. Prevalence and Distribution of Abdominal Aortic Calcium by Sex and Age-Group in a Community-based Cohort (From The Framingham Heart Study)

    PubMed Central

    Chuang, Michael L.; Massaro, Joseph M.; Levitzky, Yamini S.; Fox, Caroline S.; Manders, Emily S.; Hoffmann, Udo; O'Donnell, Christopher J.

    2012-01-01

    Abdominal aortic calcium (AAC) is associated with incident cardiovascular disease but the age and sex-related distribution of AAC in a community-dwelling population free of standard cardiovascular disease risk factors has not been described. A total of 3285 participants (aged 50.2±9.9 years) in the Framingham Heart Study Offspring and Third Generation cohorts underwent abdominal multidetector computed tomography (MDCT) scanning during 1998-2005. The presence and amount of AAC was quantified (Agatston score) by an experienced reader using standardized criteria. A healthy referent subsample (N=1656, 803 men) free of hypertension, hyperlipidemia, diabetes, obesity and smoking was identified, and participants were stratified by sex and age group (<45, 45-54, 55-64, 65-74, ≥75 years). The prevalence and burden of AAC increased monotonically and supralinearly with age in both sexes but was greater in men than women in each age group. Below age 45 <16% of referent-subsample participants had any quantifiable AAC, while above age 65 nearly 90% of referent participants had >0 AAC. Across the entire study sample, AAC prevalence and burden similarly increased with greater age. Defining the 90th percentile of referent group AAC as “high,” the prevalence of high AAC was 19% for each sex in the overall study sample. AAC also increased across categories of 10-year coronary heart disease risk, as calculated using the Framingham Risk Score, in the entire study sample. We found AAC to be widely prevalent, with the burden of AAC associated with 10-year coronary risk, in a white, free-living adult cohort. PMID:22727181

  11. Little impact of tsunami-stricken nuclear accident on awareness of radiation dose of cardiac computed tomography: A questionnaire study

    PubMed Central

    2013-01-01

    Background With the increased use of cardiac computed tomography (CT), radiation dose remains a major issue, although physicians are trying to reduce the substantial risks associated with use of this diagnostic tool. This study was performed to investigate recognition of the level of radiation exposure from cardiac CT and the differences in the level of awareness of radiation before and after the Fukushima nuclear plant accident. Methods We asked 30 physicians who were undergoing training in internal medicine to determine the equivalent doses of radiation for common radiological examinations when a normal chest X-ray is accepted as one unit; questions about the absolute radiation dose of cardiac CT data were also asked. Results According to the results, 86.6% of respondents believed the exposure to be 1 mSv at most, and 93.3% thought that the exposure was less than that of 100 chest X-rays. This finding indicates that their perceptions were far lower than the actual amounts. Even after the occurrence of such a large nuclear disaster in Fukushima, there were no significant differences in the same subjects’ overall awareness of radiation amounts. Conclusions Even after such a major social issue as the Fukushima nuclear accident, the level of awareness of the accurate radiation amount used in 64-channel multidetector CT (MDCT) by clinical physicians who order this test was not satisfactory. Thus, there is a need for the development of effective continuing education programs to improve awareness of radiation from ionizing radiation devices, including cardiac CT, and emphasis on risk-benefit evaluation based on accurate knowledge during medical training. PMID:23631688

  12. Multidetector-row computed tomography of thoracic aortic anomalies in dogs and cats: Patent ductus arteriosus and vascular rings

    PubMed Central

    2011-01-01

    Background Diagnosis of extracardiac intrathoracic vascular anomalies is of clinical importance, but remains challenging. Traditional imaging modalities, such as radiography, echocardiography, and angiography, are inherently limited by the difficulties of a 2-dimensional approach to a 3-dimensional object. We postulated that accurate characterization of malformations of the aorta would benefit from 3-dimensional assessment. Therefore, multidetector-row computed tomography (MDCT) was chosen as a 3-dimensional, new, and noninvasive imaging technique. The purpose of this study was to evaluate patients with 2 common diseases of the intrathoracic aorta, either patent ductus arteriosus or vascular ring anomaly, by contrast-enhanced 64-row computed tomography. Results Electrocardiography (ECG)-gated and thoracic nongated MDCT images were reviewed in identified cases of either a patent ductus arteriosus or vascular ring anomaly. Ductal size and morphology were determined in 6 dogs that underwent ECG-gated MDCT. Vascular ring anomalies were characterized in 7 dogs and 3 cats by ECG-gated MDCT or by a nongated thoracic standard protocol. Cardiac ECG-gated MDCT clearly displayed the morphology, length, and caliber of the patent ductus arteriosus in 6 affected dogs. Persistent right aortic arch was identified in 10 animals, 8 of which showed a coexisting aberrant left subclavian artery. A mild dilation of the proximal portion of the aberrant subclavian artery near its origin of the aorta was present in 4 dogs, and a diverticulum analogous to the human Kommerell's diverticulum was present in 2 cats. Conclusions Contrast-enhanced MDCT imaging of thoracic anomalies gives valuable information about the exact aortic arch configuration. Furthermore, MDCT was able to characterize the vascular branching patterns in dogs and cats with a persistent right aortic arch and the morphology and size of the patent ductus arteriosus in affected dogs. This additional information can be of help

  13. Evaluation of cardiovascular anomalies in patients with asymptomatic turner syndrome using multidetector computed tomography.

    PubMed

    Lee, Sun Hee; Jung, Ji Mi; Song, Min Seob; Choi, Seok jin; Chung, Woo Yeong

    2013-08-01

    Turner syndrome is well known to be associated with significant cardiovascular abnormalities. This paper studied the incidence of cardiovascular abnormalities in asymptomatic adolescent patients with Turner syndrome using multidetector computed tomography (MDCT) instead of echocardiography. Twenty subjects diagnosed with Turner syndrome who had no cardiac symptoms were included. Blood pressure and electrocardiography (ECG) was checked. Cardiovascular abnormalities were checked by MDCT. According to the ECG results, 11 had a prolonged QTc interval, 5 had a posterior fascicular block, 3 had a ventricular conduction disorder. MDCT revealed vascular abnormalities in 13 patients (65%). Three patients had an aberrant right subclavian artery, 2 had dilatation of left subclavian artery, and others had an aortic root dilatation, aortic diverticulum, and abnormal left vertebral artery. As for venous abnormalities, 3 patients had partial anomalous pulmonary venous return and 2 had a persistent left superior vena cava. This study found cardiovascular abnormalities in 65% of asymptomatic Turner syndrome patients using MDCT. Even though, there are no cardiac symptoms in Turner syndrome patients, a complete evaluation of the heart with echocardiography or MDCT at transition period to adults must be performed.

  14. SU-E-I-17: Evaluation of Commercially Available Extension Plates for the ACR CT Accreditation Phantom

    SciTech Connect

    Greene-Donnelly, K; Ogden, K

    2015-06-15

    Purpose: To evaluate the impact of commercially available extension plates on Hounsfield Unit (HU) values in the ACR CT accreditation phantom (Model 464, Gammex Inc., Middleton, Wi). The extension plates are intended to improve water HU values in scanners where the traditional solution involves scanning the phantom with an adjacent water or CTDI phantom. Methods: The Model 464 phantom was scanned on 9 different CT scanners at 8 separate sites representing 16 and 64 slice MDCT technology from four CT manufacturers. The phantom was scanned with and without the extension plates (Gammex 464 EXTPLT-KIT) in helical and axial modes. A water phantom was also scanned to verify water HU calibration. Technique was 120 kV tube potential, 350 mAs, and 210 mm display field of view. Slice thickness and reconstruction algorithm were based on site clinical protocols. The widest available beam collimation was used. Regions of interest were drawn on the HU test objects in Module 1 of the phantom and mean values recorded. Results: For all axial mode scans, water HU values were within limits with or without the extension plates. For two scanners (both Lightspeed VCT, GE Medical Systems, Waukesha WI), axial mode bone HU values were above the specified range both with and without the extension plates though they were closer to the specified range with the plates installed. In helical scan mode, two scanners (both GE Lightspeed VCT) had water HU values above the specified range without the plates installed. With the plates installed, the water HU values were within range for all scanners in all scan modes. Conclusion: Using the plates, the Lightspeed VCT scanners passed the water HU test when scanning in helical mode. The benefit of the extension plates was evident in helical mode scanning with GE scanners using a nominal 4 cm beam. Disclosure: The extension plates evaluated in this work were provided free of charge to the authors. The authors have no other financial interest in Gammex

  15. [Comparison of a dental cone beam CT with a multi-detector row CT on effective doses and physical image quality].

    PubMed

    Yoshida, Yutaka; Tokumori, Kenji; Okamura, Kazutoshi; Yoshiura, Kazunori

    2011-01-01

    The purpose of this study was to compare a dental cone beam computed tomography (dental CBCT) and a multi-detector row CT (MDCT) using effective doses and physical image quality. A dental mode (D-mode) and an implant mode (I-mode) were employed for calculating effective doses. Field of view (FOV) size of the MDCT was 150 mm. Three types of images were obtained using 3 different reconstruction functions: FC1 (for abdomen images), FC30 (for internal ear and bone images) and FC81 (for high resolution images). Effective doses obtained with the D-mode and with the I-mode were about 20% and 50% of those obtained with the MDCT, respectively. Resolution properties obtained with the D-mode and I-mode were superior to that of the MDCT in a high frequency range. Noise properties of the D-mode and the I-mode were better than those with FC81. It was found that the dental CBCT has better potential as compared with MDCT in both dental and implant modes.

  16. Diagnostic capability of gadoxetate disodium-enhanced liver MRI for diagnosis of hepatocellular carcinoma: comparison with multi-detector CT.

    PubMed

    Toyota, Naoyuki; Nakamura, Yuko; Hieda, Masashi; Akiyama, Naoko; Terada, Hiroaki; Matsuura, Noriaki; Nishiki, Masayo; Kono, Hirotaka; Kohno, Hiroshi; Irei, Toshimitsu; Yoshikawa, Yukinobu; Kuraoka, Kazuya; Taniyama, Kiyomi; Awai, Kazuo

    2013-09-01

    The purpose of this study was to evaluate the diagnostic capability of gadoxetate disodium (Gd-EOB)-MRI for the detection of hepatocellular carcinoma (HCC) compared with multidetector CT (MDCT). Fifty patients with 57 surgically proven HCCs who underwent Gd-EOB-MRI and MDCT from March 2008 to June 2011 were evaluated. Two observers evaluated MR and CT on a lesion-by-lesion basis. We analyzed sensitivity by grading on a 5-point scale, the degree of arterial enhancement and the differences in histological grades in the diffusion-weighted images (DWI). The results showed that the sensitivity of Gd-EOB-MRI was higher than that of MDCT especially for HCCs that were 1 cm in diameter or smaller. The hepatobiliary phase was useful for the detecting of small HCC. We had few cases in which it was difficult to judge HCC in the arterial enhancement between MRI and MDCT. In the diffusion-weighted image, well differentiated HCC tended to show a low signal intensity, and poorly differentiated HCC tended to show a high signal intensity. In moderately differentiated HCC's, the mean diameter of the high signal intensity group was larger than that of the low signal intensity group (24.5 mm vs. 15.8 mm). In conclusion, Gd-EOB-MRI tended to show higher sensitivity compared to MDCT in the detection of HCC.

  17. The Role of Multidetector Computed Tomography in the Early Diagnosis of Invasive Pulmonary Aspergillosis in Patients with Febrile Neutropenia Undergoing Hematopoietic Stem Cell Transplantation

    PubMed Central

    Çiledağ, Nazan; Arda, Kemal; Arıbaş, Bilgin Kadri; Tekgündüz, Ali Irfan Emre; Altuntaş, Fevzi

    2012-01-01

    Objective: To evaluate vessel involvement and the role of multidetector computed tomography (MDCT) in the earlydiagnosis of invasive pulmonary aspergillosis (IPA) in patients with febrile neutropenia and antibiotic-resistant feverundergoing autologous bone morrow transplantation. Material and Methods: In all, 74 pulmonary MDCT examinations in 37 consecutive hematopoietic stem celltransplantation patients with febrile neutropenia and clinically suspected IPA were retrospectively evaluated. Results: Diagnosis of IPA was based on Fungal Infections Cooperative Group, and National Institute of Allergy andInfectious Diseases Mycoses Study Consensus Group criteria. In all, 0, 14, and 11 patients were diagnosed as proven,probable, and possible IPA, respectively. Among the 25 patients accepted as probable and possible IPA, all had pulmonaryMDCT findings consistent with IPA. The remaining 12 patients were accepted as having fever of unknown origin (FUO)and had patent vessels based on MDCT findings.In the patients with probable and possible IPA, 72 focal pulmonary lesions were observed; in 41 of the 72 (57%) lesionsvascular occlusion was noted and the CT halo sign was observed in 25 of these 41 (61%) lesions. Resolution of feveroccurred following antifungal therapy in 19 (76%) of the 25 patients with probable and possible IPA. In all, 6 (25%)of the patients diagnosed as IPA died during follow-up. Transplant-related mortality 100 d post transplant in patientswith IPA and FUO was 24% and 0%, respectively. Conclusion: In conclusion, MDCT has a potential role in the early diagnosis of IPA via detection of vessel occlusion. PMID:24744620

  18. Patient-specific dose estimation for pediatric chest CT

    SciTech Connect

    Li Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Frush, Donald P.

    2008-12-15

    Current methods for organ and effective dose estimations in pediatric CT are largely patient generic. Physical phantoms and computer models have only been developed for standard/limited patient sizes at discrete ages (e.g., 0, 1, 5, 10, 15 years old) and do not reflect the variability of patient anatomy and body habitus within the same size/age group. In this investigation, full-body computer models of seven pediatric patients in the same size/protocol group (weight: 11.9-18.2 kg) were created based on the patients' actual multi-detector array CT (MDCT) data. Organs and structures in the scan coverage were individually segmented. Other organs and structures were created by morphing existing adult models (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. Organ and effective dose of these patients from a chest MDCT scan protocol (64 slice LightSpeed VCT scanner, 120 kVp, 70 or 75 mA, 0.4 s gantry rotation period, pitch of 1.375, 20 mm beam collimation, and small body scan field-of-view) was calculated using a Monte Carlo program previously developed and validated to simulate radiation transport in the same CT system. The seven patients had normalized effective dose of 3.7-5.3 mSv/100 mAs (coefficient of variation: 10.8%). Normalized lung dose and heart dose were 10.4-12.6 mGy/100 mAs and 11.2-13.3 mGy/100 mAs, respectively. Organ dose variations across the patients were generally small for large organs in the scan coverage (<7%), but large for small organs in the scan coverage (9%-18%) and for partially or indirectly exposed organs (11%-77%). Normalized effective dose correlated weakly with body weight (correlation coefficient: r=-0.80). Normalized lung dose and heart dose correlated strongly with mid-chest equivalent diameter (lung: r=-0.99, heart: r=-0.93); these strong correlation relationships can be used to estimate patient-specific organ dose for

  19. Can conclusions drawn from phantom-based image noise assessments be generalized to in vivo studies for the nonlinear model-based iterative reconstruction method?

    PubMed Central

    Gomez-Cardona, Daniel; Li, Ke; Hsieh, Jiang; Lubner, Meghan G.; Pickhardt, Perry J.; Chen, Guang-Hong

    2016-01-01

    Purpose: Phantom-based objective image quality assessment methods are widely used in the medical physics community. For a filtered backprojection (FBP) reconstruction-based linear or quasilinear imaging system, the use of this methodology is well justified. Many key image quality metrics acquired with phantom studies can be directly applied to in vivo human subject studies. Recently, a variety of image quality metrics have been investigated for model-based iterative image reconstruction (MBIR) methods and several novel characteristics have been discovered in phantom studies. However, the following question remains unanswered: can certain results obtained from phantom studies be generalized to in vivo animal studies and human subject studies? The purpose of this paper is to address this question. Methods: One of the most striking results obtained from phantom studies is a novel power-law relationship between noise variance of MBIR (σ2) and tube current-rotation time product (mAs): σ2 ∝ (mAs)−0.4 [K. Li et al., “Statistical model based iterative reconstruction (MBIR) in clinical CT systems: Experimental assessment of noise performance,” Med. Phys. 41, 041906 (15pp.) (2014)]. To examine whether the same power-law works for in vivo cases, experimental data from two types of in vivo studies were analyzed in this paper. All scans were performed with a 64-slice diagnostic CT scanner (Discovery CT750 HD, GE Healthcare) and reconstructed with both FBP and a MBIR method (Veo, GE Healthcare). An Institutional Animal Care and Use Committee-approved in vivo animal study was performed with an adult swine at six mAs levels (10–290). Additionally, human subject data (a total of 110 subjects) acquired from an IRB-approved clinical trial were analyzed. In this clinical trial, a reduced-mAs scan was performed immediately following the standard mAs scan; the specific mAs used for the two scans varied across human subjects and were determined based on patient size and

  20. Assessment of coronary bypass graft patency by first-line multi-detector computed tomography.

    PubMed

    Pesenti-Rossi, D; Baron, N; Georges, J-L; Augusto, S; Gibault-Genty, G; Livarek, B

    2014-11-01

    The purpose of the study was to assess whether a strategy based on a MDCT performed routinely before CA can reduce the radiation dose during the CA, without increased global exposure in patients who need imaging of CABG. A total of 147 consecutive patients were included. The radiation dose during CA (KAP 12.1 vs 22.0 Gy/cm(2), P<.01) and the volume of iodinated contrast (155 vs 200 mL, P<.02) were reduced when preceded by a MDCT. Patients' cumulative exposures were not different in the 2 strategies (5.0 vs 5.1 mSv, P=.76). MDCT performed in first line is a valuable strategy for the assessment of CABG.

  1. Assessment of modified Blalock-Taussig shunt in children with congenital heart disease using multidetector-row computed tomography.

    PubMed

    Nabo, Manal Mohamed Helmy; Hayabuchi, Yasunobu; Inoue, Miki; Watanabe, Noriko; Sakata, Miho; Kagami, Shoji

    2010-11-01

    The purpose of this study was to assess the feasibility of multidetector-row computed tomography (MDCT) for the evaluation of modified Blalock-Taussig (B-T) shunt in children with congenital heart disease associated with reduced pulmonary blood flow. A total of 25 consecutive patients (mean age, 2.6 ± 3.6 years; range, 2 months-16 years) underwent MDCT angiography of the thorax with a 16-detector row scanner prior to cardiac catheterization. A total of 39 shunts (right, 22; left, 17) were included in the study. Conventional angiographic findings were used as the gold standard for the detection of B-T shunts. Shunt diameter was measured quantitatively and independently at four sites (the subclavian artery site, the pulmonary artery site, the widest site, and the stenotic site) on MDCT and on conventional invasive angiography. All B-T shunts were depicted on multiplanar reconstruction (MPR), maximum intensity projection (MIP), curved planar reconstruction (CPR), and three-dimensional volume-rendered (VR) images, enabling evaluation in all patients except for one with occluded shunt. There were excellent correlations between MDCT- and conventional angiography-based measurements of shunt diameter at the subclavian artery site, pulmonary artery site, and the widest site (R² = 0.46, 0.74 and 0.64, respectively; p < 0.0001 for each), although systematic overestimation was observed for MDCT (mean percentage of overestimation, 23.1 ± 32.4%). Stenotic site diameter and degree of stenosis showed a mild correlation (R² = 010 and 0.25, respectively; p < 0.01 for each). This study demonstrates that MDCT is a promising tool for the detection of lesions in B-T shunts.

  2. Detection of root perforations using conventional and digital intraoral radiography, multidetector computed tomography and cone beam computed tomography

    PubMed Central

    Eskandarloo, Amir; Noruzi-Gangachin, Maruf; Khajeh, Samira

    2015-01-01

    Objectives This study aimed to compare the accuracy of conventional intraoral (CI) radiography, photostimulable phosphor (PSP) radiography, cone beam computed tomography (CBCT) and multidetector computed tomography (MDCT) for detection of strip and root perforations in endodontically treated teeth. Materials and Methods Mesial and distal roots of 72 recently extracted molar were endodontically prepared. Perforations were created in 0.2, 0.3, or 0.4 mm diameter around the furcation of 48 roots (strip perforation) and at the external surface of 48 roots (root perforation); 48 roots were not perforated (control group). After root obturation, intraoral radiography, CBCT and MDCT were taken. Discontinuity in the root structure was interpreted as perforation. Two observers examined the images. Data were analyzed using Stata software and Chi-square test. Results The sensitivity and specificity of CI, PSP, CBCT and MDCT in detection of strip perforations were 81.25% and 93.75%, 85.42% and 91.67%, 97.92% and 85.42%, and 72.92% and 87.50%, respectively. For diagnosis of root perforation, the sensitivity and specificity were 87.50% and 93.75%, 89.58% and 91.67%, 97.92% and 85.42%, and 81.25% and 87.50%, respectively. For detection of strip perforation, the difference between CBCT and all other methods including CI, PSP and MDCT was significant (p < 0.05). For detection of root perforation, only the difference between CBCT and MDCT was significant, and for all the other methods no statistically significant difference was observed. Conclusions If it is not possible to diagnose the root perforations by periapical radiographs, CBCT is the best radiographic technique while MDCT is not recommended. PMID:25671214

  3. Ankle-brachial index (ABI), abdominal aortic calcification (AAC), and coronary artery calcification (CAC): the Jackson heart study.

    PubMed

    Tullos, Bobby W; Sung, Jung Hye; Lee, Jae Eun; Criqui, Michael H; Mitchell, Marc E; Taylor, Herman A

    2013-04-01

    To examine the associations of peripheral atherosclerosis, assessed by the ABI at baseline with the extent of AAC and with CAC measured by MDCT at follow-up examination in the Jackson Heart Study cohort. Four categories of ABI: <0.90, 0.90-0.99, 1.00-1.39; >1.40. Presence of CAC/AAC was defined as scoring above the 75th percentile among participants with non-zero CT calcium scores. We conducted multivariable log-binomial models for this analysis examining the relationship between ABI and the presence of CAC or AAC using normal ABI (1.0 ≤ ABI ≤ 1.39) as the reference group. We estimated prevalence ratios adjusted for age, smoking, HTN, DM, BMI, LDL, HDL, CRP, systolic and diastolic blood pressure, and use of lipid-lowering medication. There were 2,398 patients in this analysis (women: 65 %, average age 55 years). AAC scores were not significantly different between sex. CAC scores were significantly higher in males than females regardless of ABI groups. The prevalence of significant AAC was 1.7 times higher for ABI < 0.90 (PR = 1.70; 95 % CI = 1.26-2.28; p = 0.0004) and 1.57 times higher for ABI 0.90-0.99 (PR = 1.57; 95 % CI = 1.20-2.03; p = 0.0008) than the normal ABI; AAC prevalence did not differ between subjects with ABI > 1.40 compared to those with normal ABI. The prevalence of the significant CAC was higher for ABI < 0.90 (PR = 1.55; 95 % CI = 1.12-2.14; p value = 0.0081) and ABI 0.90-0.99 (PR = 1.60; 95 % CI = 1.05-2.46; p = 0.0402) compared to normal ABI; CAC prevalence did not differ between subjects with ABI > 1.40 compared to those with normal ABI. Lower ABI was significantly associated with the extent of AAC and CAC in this cohort. ABI can provide clinicians with an inexpensive additional tool to assess vascular health and cardiovascular risk without exposing the patient to ionizing radiation.

  4. The New Approach to Sport Medicine: 3-D Reconstruction

    ERIC Educational Resources Information Center

    Ince, Alparslan

    2015-01-01

    The aim of this study is to present a new approach to sport medicine. Comparative analysis of the Vertebrae Lumbales was done in sedentary group and Muay Thai athletes. It was done by acquiring three dimensional (3-D) data and models through photogrammetric methods from the Multi-detector Computerized Tomography (MDCT) images of the Vertebrae…

  5. The imaging algorithm of millimeter-wave forward-looking SAR

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Li, Xingguang; Chen, Dianren

    2017-01-01

    It is studied a new type millimeter-wave forward-looking synthetic aperture radar (SAR) imaging algorithm in this paper, analyzes the imaging principle, echo model of point target is given, deduced the forward-looking synthetic aperture radar RD imaging algorithm, and using MATLAB imaging simulation of point target in 6, a point target simulation results from the peak of 64 * 64 slice contour and azimuth, distance to the envelope of the imaging results were analyzed, found that the distance and azimuth focusing effect is good and the side lobe does not appear distorted and tilted, proved that the system of the millimeter wave synthetic aperture radar imaging of forward-looking , simulation results demonstrate the validity of the system.

  6. Tilted cone beam VCT reconstruction algorithm

    NASA Astrophysics Data System (ADS)

    Hsieh, Jiang; Tang, Xiangyang

    2005-04-01

    Reconstruction algorithms for volumetric CT have been the focus of many studies. Several exact and approximate reconstruction algorithms have been proposed for step-and-shoot and helical scanning trajectories to combat cone beam related artifacts. In this paper, we present a closed form cone beam reconstruction formula for tilted gantry data acquisition. Although several algorithms were proposed to compensate for errors induced by the gantry tilt, none of the algorithms addresses the case in which the cone beam geometry is first rebinned to a set of parallel beams prior to the filtered backprojection. Because of the rebinning process, the amount of iso-center adjustment depends not only on the projection angle and tilt angle, but also on the reconstructed pixel location. The proposed algorithm has been tested extensively on both 16 and 64 slice VCT with phantoms and clinical data. The efficacy of the algorithm is clearly demonstrated by the experiments.

  7. Forensic imaging of projectiles using cone-beam computed tomography.

    PubMed

    von See, Constantin; Bormann, Kai-Hendrik; Schumann, Paul; Goetz, Friedrich; Gellrich, Nils-Claudius; Rücker, Martin

    2009-09-10

    In patients with gunshot injuries, it is easy to detect a projectile within the body due to the high-density of the object, but artefacts make it difficult to obtain information about the deformation and the exact location of the projectile in surrounding tissues. Cone-beam computed tomography (CBCT) is a new radiological imaging modality that allows radio-opaque objects to be localised and assessed in three dimensions. The full potential of the use of CBCT in forensic medicine has not yet been explored. In this study, three different modern projectiles were fired into the heads of pig cadavers (n=6) under standardised conditions. Tissue destruction and the location of the projectiles were analysed separately using CBCT and multi-slice computed tomography (MDCT). The projectiles had the same kinetic energy but showed considerable differences in deformation behaviour. Within the study groups, tissue destruction was reproducible. CBCT is less severely affected by metallic artefacts than MDCT. Therefore CBCT is superior in visualising bone destruction in the immediate vicinity of the projectile and projectile deformation, whereas MDCT allows soft tissue to be evaluated in more detail. CBCT is an improved diagnostic tool for the evaluation of gunshot injuries. In particular, it is superior to MDCT in detecting structural hard-tissue damage in the immediate vicinity of high-density metal projectiles and in identifying the precise location of a projectile in the body.

  8. Impact on Image Quality and Radiation Dose of Third-Generation Dual-Source Computed Tomography of the Coronary Arteries.

    PubMed

    Apfaltrer, Georg; Szolar, Dieter H; Wurzinger, Eric; Takx, Richard A P; Nance, John W; Dutschke, Anja; Tschauner, Sebastian; Loewe, Christian; Ringl, Helmut; Sorantin, Erich; Apfaltrer, Paul

    2017-04-15

    The aim of this study was to assess the image quality (IQ) and radiation dose of third-generation dual-source computed tomography (CT) coronary angiography (cCTA) in comparison with 64-slice single-source CT. This retrospective study included 140 patients (73 men, mean age 62 ± 11 years) with low-to-intermediate probability of coronary artery disease who underwent either third-generation dual-source cCTA using prospectively electrocardiography-triggered high-pitch spiral acquisition (n = 70) (group 1) or retrospective electrocardiography-gated cCTA on a 64-slice CT system (n = 70) (group 2). Contrast-to-noise and signal-to-noise ratios were measured within the aorta and coronary arteries. Subjective IQ was assessed using a 5-point Likert scale. Effective dose was estimated using specific conversion factors. The contrast-to-noise ratio of group 1 was significantly higher than group 2 at all levels (all p <0.001). Signal-to-noise ratio of group 1 was also significantly higher than group 2 (p <0.05), except for the distal left circumflex artery. Subjective IQ for group 1 was rated significantly better than for group 2 (median score [25th to 75th percentile]: 1 [1 to 2] vs 2 [2 to 3]; p <0.001). The median effective dose was 1.55 mSv (1.09 to 1.88) in group 1 versus 12.29 mSv (11.63 to 14.36) in group 2 (p <0.001) which corresponds to a mean radiation dose reduction of 87.4%. In conclusion, implementation of third-generation dual-source CT system for cCTA leads to improved IQ with significant radiation dose savings.

  9. [Two-dimensional and three-dimensional CT diagnosis of alimentary tract].

    PubMed

    Shiraga, N

    2001-10-01

    The recent development of multidetector-row CT(MDCT) has made it possible to obtain three-dimensional images of the alimentary tract that offer new diagnostic potential. In its two-dimensional diagnosis of the alimentary tract, MDCT has also changed the concept of the oral contrast agent. Before MDCT, we routinely used a positive contrast agent to distinguish the stomach and intestine from other organs and masses. The excellent slice profile acquired by MDCT can distinguish the alimentary tract and depict abnormal findings without the use of a positive contrast agent. With the use of an intravenous contrast medium, the alimentary tract itself, alimentary tumors, and inflammatory disease are well demarcated with water and air. Moreover, the combination of two-dimensional and three-dimensional diagnostic images makes it possible to detect and assess early gastric and colonic cancers as conventional gastroscopy and colonoscopy. Although the lack of texture information is one of the disadvantages of three-dimensional CT, three-dimensional CT diagnosis of the alimentary tract is less invasive and more objective than conventional studies. Advances in three-dimensional imaging with isotropic data sets will lead to the use of two-dimensional and three-dimensional CT diagnosis as one of the standard examinations of the alimentary tract.

  10. The validity of investigating occult hip fractures using multidetector CT

    PubMed Central

    Williams, Huw L M; Carpenter, Eleanor C; Lyons, Kathleen

    2016-01-01

    Objective: 10% of all hip fractures are occult on plain radiography, requiring further investigation to ascertain the diagnosis. MRI is presently the gold standard investigation, but frequently has disadvantages of time delay, resulting in increased hospital stay and mortality. Our aim was to establish whether multidetector CT (MDCT) is an appropriate first-line investigation of occult femoral neck (NOF) fractures. Methods: From 2013, we elected to use MDCT as the first-line investigation in patients believed to have an NOF fracture with negative plain films. These were reported by consultant musculoskeletal radiologists. We retrospectively analysed the data of consecutive patients presenting to the University Hospital of Wales, over 30 months with a clinical suspicion of a hip fracture. Results: 1443 patients were admitted during the study period. 209 (14.5%) patients had negative plain films requiring further investigation to exclude an NOF fracture, of which 199 patients had a CT. 93 patients had no fracture and 20 patients had isolated greater trochanter fractures. None of these patients progressed to develop an intracapsular femoral neck fracture at 4-month follow-up, although one patient sustained an extracapsular fracture following a high-energy fall whilst admitted. 26 femoral neck fractures were diagnosed on CT, whilst the remaining 60 patients were diagnosed with other pelvic ring fractures. Conclusion: When interpreted by experienced radiologists, MDCT has both sensitivity and specificity of 100%. Advances in knowledge: We recommend the use of MDCT as a safe and appropriate first-line investigation for NOF fractures. PMID:26838948

  11. Evaluation of accuracy of 3D reconstruction images using multi-detector CT and cone-beam CT

    PubMed Central

    Kim, Mija; YI, Won-Jin; Heo, Min-Suk; Lee, Sam-Sun; Choi, Soon-Chul

    2012-01-01

    Purpose This study was performed to determine the accuracy of linear measurements on three-dimensional (3D) images using multi-detector computed tomography (MDCT) and cone-beam computed tomography (CBCT). Materials and Methods MDCT and CBCT were performed using 24 dry skulls. Twenty-one measurements were taken on the dry skulls using digital caliper. Both types of CT data were imported into OnDemand software and identification of landmarks on the 3D surface rendering images and calculation of linear measurements were performed. Reproducibility of the measurements was assessed using repeated measures ANOVA and ICC, and the measurements were statistically compared using a Student t-test. Results All assessments under the direct measurement and image-based measurements on the 3D CT surface rendering images using MDCT and CBCT showed no statistically difference under the ICC examination. The measurements showed no differences between the direct measurements of dry skull and the image-based measurements on the 3D CT surface rendering images (P>.05). Conclusion Three-dimensional reconstructed surface rendering images using MDCT and CBCT would be appropriate for 3D measurements. PMID:22474645

  12. Incidence of Venous Thromboembolism Using 64 Channel Multidetector Row Computed Tomography-Indirect Venography and Anti-Coagulation Therapy after Total Knee Arthroplasty in Korea

    PubMed Central

    Park, Kyung-Hyun; Cheon, Sang-Ho; Lee, Ji-Ho

    2012-01-01

    Purpose This study evaluated the incidence of a venous thromboembolism (VTE) after total knee arthroplasty (TKA) using multidetector row computed tomography-indirect venography (MDCT-indirect venography) and assessed the efficacy of anti-coagulation therapy. Materials and Methods We enrolled 118 patients with 126 cases of TKA. The average age of the patients was 68.4 years. We used 64 channel MDCT-indirect venography for the detection of VTE. We treated selectively proximal deep vein thrombosis (DVT) or pulmonary thromboembolism (PTE) cases according to the results of MDCT-indirect venography. We re-evaluated the change in VTE using follow-up MDCT-indirect venography after 3 months. Results We identified VTE in 35.7%. DVT only was identified in 22.2% including 8 cases of proximal DVT and 20 cases of distal DVT. PTE without DVT was identified in 4.8%, and combined DVT and PTE in 8.7%. All patients with PTE were asymptomatic, but 4 DVT patients had signs of leg swelling. After anti-coagulation therapy, 20 patients showed complete resolution in 16 cases, improvement in 3 cases and one case showed a new distal DVT. Conclusions The incidence of VTE after primary TKA was 35.7% in Korea. Furthermore, anti-coagulation therapy for proximal DVT and PTE patients may be a useful method for preventing the occurrence of a fatal PTE. PMID:22570848

  13. A new 3-D diagnosis strategy for duodenal malignant lesions using multidetector row CT, CT virtual duodenoscopy, duodenography, and 3-D multicholangiography.

    PubMed

    Sata, N; Endo, K; Shimura, K; Koizumi, M; Nagai, H

    2007-01-01

    Recent advances in multidetector row computed tomography (MD-CT) technology provide new opportunities for clinical diagnoses of various diseases. Here we assessed CT virtual duodenoscopy, duodenography, and three-dimensional (3D) multicholangiography created by MD-CT for clinical diagnosis of duodenal malignant lesions. The study involved seven cases of periduodenal carcinoma (four ampullary carcinomas, two duodenal carcinomas, one pancreatic carcinoma). Biliary contrast medium was administered intravenously, followed by intravenous administration of an anticholinergic agent and oral administration of effervescent granules for expanding the upper gastrointestinal tract. Following intravenous administration of a nonionic contrast medium, an upper abdominal MD-CT scan was performed in the left lateral position. Scan data were processed on a workstation to create CT virtual duodenoscopy, duodenography, 3D multicholangiography, and various postprocessing images, which were then evaluated for their effectiveness as preoperative diagnostic tools. Carcinoma location and extent were clearly demonstrated as defects or colored low-density areas in 3-D multicholangiography images and as protruding lesions in virtual duodenography and duodenoscopy images. These findings were confirmed using multiplanar or curved planar reformation images. In conclusion, CT virtual duodenoscopy, doudenography, 3-D multicholangiography, and various images created by MD-CT alone provided necessary and adequate preoperative diagnostic information.

  14. The Role of Three-Dimensional Multidetector CT Gastrography in the Preoperative Imaging of Stomach Cancer: Emphasis on Detection and Localization of the Tumor

    PubMed Central

    Kim, Jin Woong; Heo, Suk Hee; Lim, Hyo Soon; Lim, Nam Yeol; Park, Young Kyu; Jeong, Yong Yeon; Kang, Heoung Keun

    2015-01-01

    Multidetector CT (MDCT) gastrography has been regarded as a promising technique for the preoperative imaging of gastric cancer. It has the ability to produce various three-dimensional (3D) images. Because 3D reconstruction images are more effective and intuitive for recognizing abnormal changes in the gastric folds and subtle mucosal nodularity than two-dimensional images, 3D MDCT gastrography can enhance the detection rate of early gastric cancer, which, in turn, contributes to the improvement of the accuracy of preoperative tumor (T) staging. In addition, shaded surface display and tissue transition projection images provide a global view of the stomach, with the exact location of gastric cancer, which may replace the need for barium studies. In this article, we discuss technical factors in producing high-quality MDCT gastrographic images and present cases demonstrating the usefulness of MDCT gastrography for the detection and T staging of gastric cancer while emphasizing the significance of preoperative localization of gastric cancer in terms of surgical margin. PMID:25598676

  15. Computer-based route-definition system for peripheral bronchoscopy.

    PubMed

    Graham, Michael W; Gibbs, Jason D; Higgins, William E

    2012-04-01

    Multi-detector computed tomography (MDCT) scanners produce high-resolution images of the chest. Given a patient's MDCT scan, a physician can use an image-guided intervention system to first plan and later perform bronchoscopy to diagnostic sites situated deep in the lung periphery. An accurate definition of complete routes through the airway tree leading to the diagnostic sites, however, is vital for avoiding navigation errors during image-guided bronchoscopy. We present a system for the robust definition of complete airway routes suitable for image-guided bronchoscopy. The system incorporates both automatic and semiautomatic MDCT analysis methods for this purpose. Using an intuitive graphical user interface, the user invokes automatic analysis on a patient's MDCT scan to produce a series of preliminary routes. Next, the user visually inspects each route and quickly corrects the observed route defects using the built-in semiautomatic methods. Application of the system to a human study for the planning and guidance of peripheral bronchoscopy demonstrates the efficacy of the system.

  16. SU-E-I-21: Dosimetric Characterization and Image Quality Evaluation of the AIRO Mobile CT Scanner

    SciTech Connect

    Weir, V; Zhang, J; Bruner, A

    2015-06-15

    Purpose: The AIRO Mobile CT system was recently introduced which overcomes the limitations from existing CT, CT fluoroscopy, and intraoperative O-arm. With an integrated table and a large diameter bore, the system is suitable for cranial, spine and trauma procedures, making it a highly versatile intraoperative imaging system. This study is to investigate radiation dose and image quality of the AIRO and compared with those from a routine CT scanner. Methods: Radiation dose was measured using a conventional 100mm pencil ionization chamber and CT polymethylmetacrylate (PMMA) body and head phantoms. Image quality was evaluated with a CATPHAN 500 phantom. Spatial resolution, low contrast resolution (CNR), Modulation Transfer Function (MTF), and Normalized Noise Power Spectrum (NNPS) were analyzed. Results: Under identical technique conditions, radiation dose (mGy/mAs) from the AIRO mobile CT system (AIRO) is higher than that from a 64 slice CT scanner. MTFs show that both Soft and Standard filters of the AIRO system lost resolution quickly compared to the Sensation 64 slice CT. With the Standard kernel, the spatial resolutions of the AIRO system are 3lp/cm and 4lp/cm for the body and head FOVs, respectively. NNPSs show low frequency noise due to ring-like artifacts. Due to a higher dose in terms of mGy/mAs at both head and body FOV, CNR of the AIRO system is higher than that of the Siemens scanner. However detectability of the low contrast objects is poorer in the AIRO due to the presence of ring artifacts in the location of the targets. Conclusion: For image guided surgery applications, the AIRO has some advantages over a routine CT scanner due to its versatility, large bore size, and acceptable image quality. Our evaluation of the physical performance helps its future improvements.

  17. A pilot study employing hepatic intra-arterial irinotecan injection of drug-eluting beads as salvage therapy in liver metastatic colorectal cancer patients without extrahepatic involvement: the first southern Italy experience

    PubMed Central

    Ranieri, Girolamo; Niccoli Asabella, Artor; Altini, Corinna; Fazio, Vito; Caporusso, Luciana; Marech, Ilaria; Vinciarelli, Gianluca; Macina, Francesco; de Ceglia, Dario; Fanelli, Margherita; Ammendola, Michele; Rubini, Giuseppe; Gadaleta, Cosmo Damiano

    2016-01-01

    Background The main aim of this prospective study was to evaluate the efficacy of drug-eluting beads with irinotecan (DEBIRI) for liver metastases from colorectal cancer. Secondary aims were to evaluate survival and toxicity. Methods Twenty-five patients with metastases in <50% of the liver and without extrahepatic involvement were enrolled. Treatment response assessment was performed by multidetector contrast enhancement computed tomography (MDCT) with evaluation of the enhancement pattern of the target lesion and tumor response rates according to modified Response Evaluation Criteria in Solid Tumors (mRECIST, Version 1.1). All adverse events were recorded by the Cancer Therapy Evaluation Program Common Terminology Criteria for Adverse Events, Version 3.0. Associations of tumor response and variables were calculated using the chi-squared test. Overall survival (OS) was calculated using the Kaplan–Meier method. Comparisons were made using the log-rank test. Results According to mRECIST, complete response (CR) was observed in 21.8% of patients, partial response (PR) in 13%, stable disease (SD) in 52.2% and progressive disease (PD) in 13% of patients. Response rate (RR = CR + PR) was 34.8%. No associations between treatment response and variables such as Dukes’ classification, grading and Kras status were found (P>0.05). The median OS was 37 months (95% CI: 13.881 to 60.119). Cox regression model showed that neither site, Dukes’ classification, grading, Kras status nor number of chemotherapy treatments pre-DEBIRI influenced the OS. The log-rank test showed no statistically significant difference in OS among patients who underwent 1, 2 or 3 DEBIRI treatments (χ2=2.831, P=0.09). In our study, the main toxicities included postembolization syndrome (PES), hypertransaminasemia and fever. Conclusion The favorable tumor response and the favorable toxicity profile make DEBIRI treatment a potential third-line therapy. Although further larger studies are needed to

  18. MO-E-17A-08: Attenuation-Based Size Adjusted, Scanner-Independent Organ Dose Estimates for Head CT Exams: TG 204 for Head CT

    SciTech Connect

    McMillan, K; Bostani, M; Cagnon, C; McNitt-Gray, M; Zankl, M; DeMarco, J

    2014-06-15

    Purpose: AAPM Task Group 204 described size specific dose estimates (SSDE) for body scans. The purpose of this work is to use a similar approach to develop patient-specific, scanner-independent organ dose estimates for head CT exams using an attenuation-based size metric. Methods: For eight patient models from the GSF family of voxelized phantoms, dose to brain and lens of the eye was estimated using Monte Carlo simulations of contiguous axial scans for 64-slice MDCT scanners from four major manufacturers. Organ doses were normalized by scannerspecific 16 cm CTDIvol values and averaged across all scanners to obtain scanner-independent CTDIvol-to-organ-dose conversion coefficients for each patient model. Head size was measured at the first slice superior to the eyes; patient perimeter and effective diameter (ED) were measured directly from the GSF data. Because the GSF models use organ identification codes instead of Hounsfield units, water equivalent diameter (WED) was estimated indirectly. Using the image data from 42 patients ranging from 2 weeks old to adult, the perimeter, ED and WED size metrics were obtained and correlations between each metric were established. Applying these correlations to the GSF perimeter and ED measurements, WED was calculated for each model. The relationship between the various patient size metrics and CTDIvol-to-organ-dose conversion coefficients was then described. Results: The analysis of patient images demonstrated the correlation between WED and ED across a wide range of patient sizes. When applied to the GSF patient models, an exponential relationship between CTDIvol-to-organ-dose conversion coefficients and the WED size metric was observed with correlation coefficients of 0.93 and 0.77 for the brain and lens of the eye, respectively. Conclusion: Strong correlation exists between CTDIvol normalized brain dose and WED. For the lens of the eye, a lower correlation is observed, primarily due to surface dose variations. Funding

  19. TU-E-201-02: Eye Lens Dosimetry From CT Perfusion Studies

    SciTech Connect

    Zhang, D.

    2015-06-15

    awareness can lead to avoidance or even prevention. Learning Objectives: To understand recent changes in eye lens dose limits and thresholds for tissue reactions To understand different approaches to dose estimation for eye lens To learn about challenges in eye lens opacities among staff in interventional fluoroscopy Di Zhang, Toshiba America Medical Systems, Tustin, CA, USA Eye lens radiation dose from brain perfusion CT exams CT perfusion imaging requires repeatedly exposing one location of the head to monitor the uptake and washout of iodinated contrast. The accumulated radiation dose to the eye lens can be high, leading to concerns about potential radiation injury from these scans. CTDIvol assumes continuous z coverage and can overestimate eye lens dose in CT perfusion scans where the table do not increment. The radiation dose to the eye lens from clinical CT brain perfusion studies can be estimated using Monte Carlo simulation methods on voxelized patient models. MDCT scanners from four major manufacturers were simulated and the eye lens doses were estimated using the AAPM posted clinical protocols. They were also compared to CTDIvol values to evaluate the overestimation from CTDIvol. The efficacy of eye lens dose reduction techniques such as tilting the gantry and moving the scan location away from the eyelens were also investigated. Eye lens dose ranged from 81 mGy to 279 mGy, depending on the scanner and protocol used. It is between 59% and 63% of the CTDIvol values reported by the scanners. The eye lens dose is significantly reduced when the eye lenses were not directly irradiated. CTDIvol should not be interpreted as patient dose; this study has shown it to overestimate dose to the eye lens. These results may be used to provide more accurate estimates of actual dose to ensure that protocols are operated safely below thresholds. Tilting the gantry or moving the scanning region further away from the eyes are effective for reducing lens dose in clinical practice

  20. Who Studies Women's Studies?

    ERIC Educational Resources Information Center

    Price, Marion; Owen, Mairead

    1998-01-01

    Studied a cohort (originally 44) of students who entered a British university to study women's studies in 1994. The strong emphases on the salience of the students' choice and the experiential importance of identity as a concept were striking. Theoretical difficulties in theorizing identity are explored. (SLD)

  1. Gd-EOB-DTPA-enhanced 3.0-Tesla MRI findings for the preoperative detection of focal liver lesions: Comparison with iodine-enhanced multi-detector computed tomography

    NASA Astrophysics Data System (ADS)

    Park, Hyong-Hu; Goo, Eun-Hoe; Im, In-Chul; Lee, Jae-Seung; Kim, Moon-Jib; Kwak, Byung-Joon; Chung, Woon-Kwan; Dong, Kyung-Rae

    2012-12-01

    The safety of gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid (Gd-EOB-DTPA) has been confirmed, but more study is needed to assess the diagnostic accuracy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) in patients with a hepatocellular carcinoma (HCC) for whom surgical treatment is considered or with a metastatic hepatoma. Research is also needed to examine the rate of detection of hepatic lesions compared to multi-detector computed tomography (MDCT), which is used most frequently to localize and characterize a HCC. Gd-EOB-DTPA-enhanced MRI and iodine-enhanced MDCT imaging were compared for the preoperative detection of focal liver lesions. The clinical usefulness of each method was examined. The current study enrolled 79 patients with focal liver lesions who preoperatively underwent MRI and MDCT. In these patients, there was less than one month between the two diagnostic modalities. Imaging data were taken before and after contrast enhancement in both methods. To evaluate the images, we analyzed the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) in the lesions and the liver parenchyma. To compare the sensitivity of the two methods, we performed a quantitative analysis of the percentage signal intensity of the liver (PSIL) on a high resolution picture archiving and communication system (PACS) monitor (paired-samples t-test, p < 0.05). The enhancement was evaluated based on a consensus of four observers. The enhancement pattern and the morphological features during the arterial and the delayed phases were correlated between the Gd-EOB-DTPA-enhanced MRI findings and the iodine-enhanced MDCT by using an adjusted x2 test. The SNRs, CNRs, and PSIL all had a greater detection rate in Gd-EOB-DTPA enhanced MRI than in iodine-enhanced MDCT. Hepatocyte-selective uptake was observed 20 minutes after the injection in the focal nodular hyperplasia (FNH, 9/9), adenoma (9/10), and highly-differentiated HCC (grade G1, 27/30). Rim

  2. TU-E-201-01: Methods for Eye Lens Dosimetry and Studies On Lens Opacities with Interventionists

    SciTech Connect

    Rehani, M.

    2015-06-15

    awareness can lead to avoidance or even prevention. Learning Objectives: To understand recent changes in eye lens dose limits and thresholds for tissue reactions To understand different approaches to dose estimation for eye lens To learn about challenges in eye lens opacities among staff in interventional fluoroscopy Di Zhang, Toshiba America Medical Systems, Tustin, CA, USA Eye lens radiation dose from brain perfusion CT exams CT perfusion imaging requires repeatedly exposing one location of the head to monitor the uptake and washout of iodinated contrast. The accumulated radiation dose to the eye lens can be high, leading to concerns about potential radiation injury from these scans. CTDIvol assumes continuous z coverage and can overestimate eye lens dose in CT perfusion scans where the table do not increment. The radiation dose to the eye lens from clinical CT brain perfusion studies can be estimated using Monte Carlo simulation methods on voxelized patient models. MDCT scanners from four major manufacturers were simulated and the eye lens doses were estimated using the AAPM posted clinical protocols. They were also compared to CTDIvol values to evaluate the overestimation from CTDIvol. The efficacy of eye lens dose reduction techniques such as tilting the gantry and moving the scan location away from the eyelens were also investigated. Eye lens dose ranged from 81 mGy to 279 mGy, depending on the scanner and protocol used. It is between 59% and 63% of the CTDIvol values reported by the scanners. The eye lens dose is significantly reduced when the eye lenses were not directly irradiated. CTDIvol should not be interpreted as patient dose; this study has shown it to overestimate dose to the eye lens. These results may be used to provide more accurate estimates of actual dose to ensure that protocols are operated safely below thresholds. Tilting the gantry or moving the scanning region further away from the eyes are effective for reducing lens dose in clinical practice

  3. Horseshoe lung associated with left-lung hypoplasia, left pulmonary artery sling and bilateral agenesis of upper lobe bronchi.

    PubMed

    Oguz, Berna; Alan, Serdar; Ozcelik, Ugur; Haliloglu, Mithat

    2009-09-01

    Horseshoe lung, a rare congenital anomaly, is almost always associated with unilateral (usually right-sided) lung hypoplasia, and, in most cases, in conjunction with the scimitar syndrome. We present an 8-month-old boy with horseshoe lung associated with left-lung hypoplasia, left pulmonary artery sling and bilateral agenesis of the upper lobe bronchi, diagnosed by multidetector CT (MDCT) imaging. The study also revealed an anomalous origin of the left vertebral artery as the last branch of the aortic arch, distal to the left subclavian artery, and an anomalous origin of the left common carotid artery from the brachiocephalic trunk. A hemivertebral anomaly of the seventh cervical vertebra was incidentally detected. MDCT with high-quality multiplanar and three-dimensional reconstructions is a noninvasive and rapid technique for detecting the complex combination of vascular, tracheobronchial and parenchymal anomalies, and any potential bone anomalies, in one imaging study.

  4. Surgically Cured, Relapsed Pneumococcal Meningitis Due to Bone Defects, Non-invasively Identified by Three-dimensional Multi-detector Computed Tomography

    PubMed Central

    Akimoto, Takayoshi; Morita, Akihiko; Shiobara, Keiji; Hara, Makoto; Minami, Masayuki; Shijo, Katsunori; Nomura, Yasuyuki; Shigihara, Shuntaro; Haradome, Hiroki; Abe, Osamu; Kamei, Satoshi

    2016-01-01

    A 43-year-old Japanese man presented with a history of bacterial meningitis (BM). He was admitted to our department with a one-day history of headache and was diagnosed with relapse of BM based on the cerebrospinal fluid findings. The conventional imaging studies showed serial findings suggesting left otitis media, a temporal cephalocele, and meningitis. Three-dimensional multi-detector computed tomography (3D-MDCT) showed left petrous bone defects caused by the otitis media, and curative surgical treatment was performed. Skull bone structural abnormalities should be considered a cause of relapsed BM. 3D-MDCT was useful for revealing the causal minimal bone abnormality and performing pre-surgical mapping. PMID:27980270

  5. A method of estimating conceptus doses resulting from multidetector CT examinations during all stages of gestation

    SciTech Connect

    Damilakis, John; Tzedakis, Antonis; Perisinakis, Kostas; Papadakis, Antonios E.

    2010-12-15

    Purpose: Current methods for the estimation of conceptus dose from multidetector CT (MDCT) examinations performed on the mother provide dose data for typical protocols with a fixed scan length. However, modified low-dose imaging protocols are frequently used during pregnancy. The purpose of the current study was to develop a method for the estimation of conceptus dose from any MDCT examination of the trunk performed during all stages of gestation. Methods: The Monte Carlo N-Particle (MCNP) radiation transport code was employed in this study to model the Siemens Sensation 16 and Sensation 64 MDCT scanners. Four mathematical phantoms were used, simulating women at 0, 3, 6, and 9 months of gestation. The contribution to the conceptus dose from single simulated scans was obtained at various positions across the phantoms. To investigate the effect of maternal body size and conceptus depth on conceptus dose, phantoms of different sizes were produced by adding layers of adipose tissue around the trunk of the mathematical phantoms. To verify MCNP results, conceptus dose measurements were carried out by means of three physical anthropomorphic phantoms, simulating pregnancy at 0, 3, and 6 months of gestation and thermoluminescence dosimetry (TLD) crystals. Results: The results consist of Monte Carlo-generated normalized conceptus dose coefficients for single scans across the four mathematical phantoms. These coefficients were defined as the conceptus dose contribution from a single scan divided by the CTDI free-in-air measured with identical scanning parameters. Data have been produced to take into account the effect of maternal body size and conceptus position variations on conceptus dose. Conceptus doses measured with TLD crystals showed a difference of up to 19% compared to those estimated by mathematical simulations. Conclusions: Estimation of conceptus doses from MDCT examinations of the trunk performed on pregnant patients during all stages of gestation can be made

  6. Anatomical variation of celiac axis, superior mesenteric artery, and hepatic artery: Evaluation with multidetector computed tomography angiography

    PubMed Central

    Farghadani, Maryam; Momeni, Mohammad; Hekmatnia, Ali; Momeni, Fateme; Baradaran Mahdavi, Mohammad Mehdi

    2016-01-01

    Background: The celiac axis, superior mesenteric artery (SMA), and hepatic artery are the most important branches of abdominal aorta due to their vascularization field. The aim of our study was to evaluate the prevalence of different anatomical variation of celiac axis, SMA, hepatic artery, and its branches with multidetector computed tomography (MDCT) angiography of upper abdomen arteries. Materials and Methods: MDCT of 607 kidney donor and traumatic patients that referred to MDCT unit at Al Zahra Hospital in Isfahan from 2012 to 2015 were retrospectively evaluated. We excluded patients with history of abdominal vascular surgery and hepatic or pancreatic surgery. Computed tomography images of the patient were obtained with 64-row MDCT scanner and anatomical variations were analyzed. Results: Three hundred and eighty-eight (63.9%) of the 607 patients had classic arterial anatomy and 219 (36.1%) patients had variant types. The most common type of variation was the origin of the right hepatic artery (RHA) from SMA (9.6%), and the next common variation was the origin of the left hepatic artery (LHA) from the left gastric artery (6.9%). Variations in the origin of the common hepatic artery (CHA) were seen in 16 (2.6%) patients. Buhler arc was identified in two patients. The RHA originated from the celiac axis in 11 (1.8%) patients and from the aorta in 8 (1.3%) patients. Trifurcation of CHA into gastroduodenal artery, RHA, and LHA was detected in 11 (1.8%) patients. Conclusion: The results of the present study showed that anatomical variation occurs in a high percentage of patients. Detection of these variations can guide surgical and radiological interventional planning.

  7. Predictive Ability of Preoperative CT Scan in Determining Whether the Adrenal Gland is Spared at Radical Nephrectomy

    PubMed Central

    Nason, Gregory J.; Aslam, Asadullah; Giri, Subhasis K.

    2016-01-01

    Introduction The aim of this study was to assess whether preoperative multiple detector computed tomography (MDCT) accurately predicts adrenal involvement for patients undergoing non-adrenal sparing radical nephrectomy for renal cell carcinoma. Methods and Materials A retrospective observational study based on a composite patient population of two university teaching hospitals who underwent radical nephrectomy. Sensitivity, specificity, overall accuracy, positive and negative predictive values and likelihood ratios were calculated from radiological reports. Results Total 579 patients underwent radical nephrectomy, of which 199 (34.4%) patients underwent a non-adrenal sparing radical nephrectomy, in which 128 (64.3%) were male and 118 (59.3%) were left side tumors. Mean tumor size was 8.2 cm (range 1.4-20cm). MDCT was found to have a sensitivity of 100% and specificity of 95.2% for identifying adrenal invasion. Total 179 patients (89.9%) had a radiographically normal ipsilateral adrenal gland, of which none were found to have adrenal involvement. Therefore, the negative predictive value of preoperative cross-sectional imaging for identification of adrenal involvement was 100%. Conclusion Cross- sectional MDCT imaging accurately predicts adrenal involvement and the decision to remove or spare the adrenal gland should be made preoperative planning regardless of tumour size or location at the time of multi-disciplinary discussion unless there is intraoperative evidence of adrenal invasion. PMID:27867332

  8. 256-slice CT coronary angiography in atrial fibrillation: The impact of mean heart rate and heart rate variability on image quality

    NASA Astrophysics Data System (ADS)

    Chen, Liang-Kuang; Hsu, Shih-Ming; Mok, Greta S. P.; Law, Wei-Yip; Lu, Kun-Mu; Yang, Ching-Ching; Wu, Tung-Hsin

    2011-08-01

    The aim of this study was to evaluate the image quality of 256-MDCT in atrial fibrillation and to compare the findings with those among patients in sinus rhythm.MaterialsAll reconstructed images were evaluated by two independent experienced readers blinded to patient information, heart rate, and ECG results to assess the diagnostic quality of images of the coronary artery segments using axial images, multi-planar reformations, maximum intensity projections, and volume rendering technique.ResultsNo statistical significance was detected in terms of the overall image quality between patients in sinus rhythm and with atrial fibrillation. Pearson's correlation analysis showed no significant association between image quality and mean heart rate no matter for patients in sinus rhythm or with atrial fibrillation. Similarly, there was no correlation between image quality and heart rate variability for either patients in sinus rhythm or with atrial fibrillation. Our results showed that the optimal reconstruction window depends on patient's HR, and the pattern for patients in atrial fibrillation is similar to that obtained from non-atrial fibrillation patients.ConclusionThis study shows the potential of using 256-MDCT coronary angiography in patients with atrial fibrillation. Our results suggest that when appropriate reconstruction timing window is applied, patients with atrial fibrillation do not have to be excluded from MDCT coronary angiographic examinations.

  9. Risk of vertebral compression fractures in multiple myeloma patients

    PubMed Central

    Anitha, D.; Thomas, Baum; Jan, Kirschke S.; Subburaj, Karupppasamy

    2017-01-01

    Abstract The purpose of this study was to develop and validate a finite element (FE) model to predict vertebral bone strength in vitro using multidetector computed tomography (MDCT) images in multiple myeloma (MM) patients, to serve as a complementing tool to assess fracture risk. In addition, it also aims to differentiate MM patients with and without vertebral compression fractures (VCFs) by performing FE analysis on vertebra segments (T1–L5) obtained from in vivo routine MDCT imaging scans. MDCT-based FE models were developed from the in vitro vertebrae samples and were then applied to the in vivo vertebrae segments of MM patients (n = 4) after validation. Predicted fracture load using FE models correlated significantly with experimentally measured failure load (r = 0.85, P < 0.001). Interestingly, an erratic behavior was observed in patients with fractures (n = 2) and a more gradual change in FE-predicted strength values in patients without fractures (n = 2). Severe geometric deformations were also observed in models that have already attained fractures. Since BMD is not a reliable parameter for fracture risk prediction in MM subjects, it is necessary to use advanced tools such as FE analysis to predict individual fracture risk. If peaks are observed between adjacent segments in an MM patient, it can be safe to conclude that the spine is experiencing regions of structural instability. Such an FE visualization may have therapeutic consequences to prevent MM associated vertebral fractures. PMID:28079810

  10. Validation of the Australian diagnostic reference levels for paediatric multi detector computed tomography: a comparison of RANZCR QUDI data and subsequent NDRLS data from 2012 to 2015.

    PubMed

    Anna, Hayton; Wallace, Anthony; Thomas, Peter

    2017-03-01

    The national diagnostic reference level service (NDRLS), was launched in 2011, however no paediatric data were submitted during the first calendar year of operation. As such, Australian national diagnostic reference levels (DRLs), for paediatric multi detector computed tomography (MDCT), were established using data obtained from a Royal Australian and New Zealand College of Radiologists (RANZCR), Quality Use of Diagnostic Imaging (QUDI), study. Paediatric data were submitted to the NDRLS in 2012 through 2015. An analysis has been made of the NDRLS paediatric data using the same method as was used to analyse the QUDI data to establish the Australian national paediatric DRLs for MDCT. An analysis of the paediatric NDRLS data has also been made using the method used to calculate the Australian national adult DRLs for MDCT. A comparison between the QUDI data and subsequent NDRLS data shows the NDRLS data to be lower on average for the Head and AbdoPelvis protocol and similar for the chest protocol. Using an average of NDRLS data submitted between 2012 and 2015 implications for updated paediatric DRLS are considered.

  11. Asbestos Surveillance Program Aachen (ASPA): initial results from baseline screening for lung cancer in asbestos-exposed high-risk individuals using low-dose multidetector-row CT.

    PubMed

    Das, Marco; Mühlenbruch, Georg; Mahnken, Andreas H; Hering, K G; Sirbu, H; Zschiesche, W; Knoll, Lars; Felten, Michael K; Kraus, Thomas; Günther, Rolf W; Wildberger, Joachim E

    2007-05-01

    The purpose of this study was to assess the prevalence of lung cancer in a high-risk asbestos-exposed cohort using low-dose MDCT. Of a population of 5,389 former power-plant workers, 316 were characterized as individuals at highest risk for lung cancer according to a lung-cancer risk model including age, asbestos exposure and smoking habits. Of these 316, 187 (mean age: 66.6 years) individuals were included in a prospective trial. Mean asbestos exposure time was 29.65 years and 89% were smokers. Screening was performed on a 16-slice MDCT (Siemens) with low-dose technique (10/20 mAs(eff.); 1 mm/0.5 mm increment). In addition to soft copy PACS reading analysis on a workstation with a dedicated lung analysis software (LungCARE; Siemens) was performed. One strongly suspicious mass and eight cases of histologically proven lung cancer were found plus 491 additional pulmonary nodules (average volume: 40.72 ml, average diameter 4.62 mm). Asbestos-related changes (pleural plaques, fibrosis) were visible in 80 individuals. Lung cancer screening in this high-risk cohort showed a prevalence of lung cancer of 4.28% (8/187) at baseline screening with an additional large number of indeterminate pulmonary nodules. Low-dose MDCT proved to be feasible in this highly selected population.

  12. The reverse Segond fracture: not associated with knee dislocation and rarely with posterior cruciate ligament tear.

    PubMed

    Peltola, Erno K; Lindahl, Jan; Koskinen, Seppo K

    2014-06-01

    The aims of this study were to assess the incidence of reverse Segond fracture, to examine the associated ligamentous injuries, and to examine how often reverse Segond fracture coexists with a knee dislocation. At a level 1 trauma center, an 11-year period of emergency department multidetector-row computed tomography (MDCT) examinations for knee trauma was evaluated for reverse Segond and Segond fractures. Surgical findings served as the reference standard for intra-articular injuries. The hospital discharge register was searched for the diagnosis of knee dislocation from August 2000 through the end of August 2011. A total of 1,553 knee MDCT examinations were evaluated. Ten patients with a reverse Segond fracture were found, comprising 0.64 % of emergency room acute knee trauma MDCT examinations. Seven patients who had a reverse Segond fracture were operated: Three had an avulsion fracture of the anterior cruciate ligament, one had an avulsion fracture of posterior cruciate ligament, two had a lateral meniscal tear, and two had a medial collateral ligament tear. The ratio of reverse Segond fractures to Segond fractures was 1:4. None of the 71 knee dislocation patients had a reverse Segond fracture. Reverse Segond fracture is a rare finding even in a level 1 trauma center. Cruciate ligament injuries appear to be associated with avulsion fracture, but every patient does not have PCL injury, as previously reported. Our results do not support the association of knee dislocation with reverse Segond fracture.

  13. Predicting the biomechanical strength of proximal femur specimens with Minkowski functionals and support vector regression

    NASA Astrophysics Data System (ADS)

    Yang, Chien-Chun; Nagarajan, Mahesh B.; Huber, Markus B.; Carballido-Gamio, Julio; Bauer, Jan S.; Baum, Thomas; Eckstein, Felix; Lochmüller, Eva-Maria; Link, Thomas M.; Wismüller, Axel

    2014-03-01

    Regional trabecular bone quality estimation for purposes of femoral bone strength prediction is important for improving the clinical assessment of osteoporotic fracture risk. In this study, we explore the ability of 3D Minkowski Functionals derived from multi-detector computed tomography (MDCT) images of proximal femur specimens in predicting their corresponding biomechanical strength. MDCT scans were acquired for 50 proximal femur specimens harvested from human cadavers. An automated volume of interest (VOI)-fitting algorithm was used to define a consistent volume in the femoral head of each specimen. In these VOIs, the trabecular bone micro-architecture was characterized by statistical moments of its BMD distribution and by topological features derived from Minkowski Functionals. A linear multiregression analysis and a support vector regression (SVR) algorithm with a linear kernel were used to predict the failure load (FL) from the feature sets; the predicted FL was compared to the true FL determined through biomechanical testing. The prediction performance was measured by the root mean square error (RMSE) for each feature set. The best prediction result was obtained from the Minkowski Functional surface used in combination with SVR, which had the lowest prediction error (RMSE = 0.939 ± 0.345) and which was significantly lower than mean BMD (RMSE = 1.075 ± 0.279, p<0.005). Our results indicate that the biomechanical strength prediction can be significantly improved in proximal femur specimens with Minkowski Functionals extracted from on MDCT images used in conjunction with support vector regression.

  14. Is Routine Thromboprophylaxis Needed in Korean Patients Undergoing Unicompartmental Knee Arthroplasty?

    PubMed

    Koh, In Jun; Kim, Ju Hwan; Kim, Man Soo; Jang, Sung Won; Kim, Chulkyu; In, Yong

    2016-03-01

    This study was undertaken to determine the prevalence and the natural course of venous thromboembolism (VTE) without thromboprophylaxis to ascertain whether routine thromboprophylaxis is necessary following unicompartmental knee arthroplasty (UKA) in Korean patients. The medical records and multidetector row computed tomography (MDCT) imaging of the consecutive 77 UKAs in 70 patients were reviewed. In all patients, MDCTs were undertaken preoperatively and at 1-week after surgery, and VTE symptoms were evaluated. At postoperative 6-months, follow-up MDCTs were undertaken in all patients in whom VTEs were newly detected after surgery. VTE lesions were newly detected in 18 (26%) of the 70 patients. However, none of the patients complained of VTE-related symptoms and MDCT demonstrated that all VTEs were small and involved limited portion without lower leg edema or pleuroparenchymal complication. At the 6-month follow up MDCT, all types of VTEs were shown to be completely resolved, regardless of their location. All of the VTE lesions maintained an asymptomatic status for 6-month after surgery. VTE following UKA in Korean patients who do not receive thromboprophylaxis seems to occur frequently, but all of the VTEs are clinically insignificant and all VTEs are spontaneously regressed. Routine thromboprophylaxis or thrombolytic treatment in Korean patients undergoing UKA may not be necessary.

  15. Numerical Analysis of Organ Doses Delivered During Computed Tomography Examinations Using Japanese Adult Phantoms with the WAZA-ARI Dosimetry System.

    PubMed

    Takahashi, Fumiaki; Sato, Kaoru; Endo, Akira; Ono, Koji; Ban, Nobuhiko; Hasegawa, Takayuki; Katsunuma, Yasushi; Yoshitake, Takayasu; Kai, Michiaki

    2015-08-01

    A dosimetry system for computed tomography (CT) examinations, named WAZA-ARI, is being developed to accurately assess radiation doses to patients in Japan. For dose calculations in WAZA-ARI, organ doses were numerically analyzed using average adult Japanese male (JM) and female (JF) phantoms with the Particle and Heavy Ion Transport code System (PHITS). Experimental studies clarified the photon energy distribution of emitted photons and dose profiles on the table for some multi-detector row CT (MDCT) devices. Numerical analyses using a source model in PHITS could specifically take into account emissions of x rays from the tube to the table with attenuation of photons through a beam-shaping filter for each MDCT device based on the experiment results. The source model was validated by measuring the CT dose index (CTDI). Numerical analyses with PHITS revealed a concordance of organ doses with body sizes of the JM and JF phantoms. The organ doses in the JM phantoms were compared with data obtained using previously developed systems. In addition, the dose calculations in WAZA-ARI were verified with previously reported results by realistic NUBAS phantoms and radiation dose measurement using a physical Japanese model (THRA1 phantom). The results imply that numerical analyses using the Japanese phantoms and specified source models can give reasonable estimates of dose for MDCT devices for typical Japanese adults.

  16. Current evidence for the diagnostic value of gadoxetic acid-enhanced magnetic resonance imaging for liver metastasis.

    PubMed

    Tsurusaki, Masakatsu; Sofue, Keitaro; Murakami, Takamichi

    2016-08-01

    A variety of imaging techniques, including ultrasonography (US), multidetector computed tomography (MDCT), magnetic resonance imaging (MRI) and positron emission tomography combined with CT scan (PET/CT), are available for diagnosis and treatment planning in liver metastasis. Contrast-enhanced MDCT is a relatively non-invasive, widely available and standardized method for hepatic work-up. Gadoxetic acid (gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid; EOB Primovist®]) is a recently developed liver-specific hepatobiliary MR contrast agent that offers both dynamic imaging as well as liver-specific static hepatocyte imaging, referred to as the hepatobiliary phase. Following contrast injection, this technique reveals dynamic vascular phases (arterial, portal venous and delayed phases), in addition to the hepatobiliary phase upon uptake by functional hepatocytes. The overall sensitivity of gadoxetic acid-enhanced MRI was significantly higher than that of contrast-enhanced CT. Specifically, the higher sensitivity of gadoxetic acid-enhanced MRI was observed in lesions smaller than 1 cm in diameter. Gadoxetic acid-enhanced MRI is considered an extremely useful tool for the diagnosis of liver metastases. Future studies will focus on diagnostic algorithms involving combinations of modalities such as MRI, MDCT and/or (18) F-fluorodeoxyglucose PET/CT, which may impact the treatment plan for these patients.

  17. Dedicated multi-detector CT of the esophagus: spectrum of diseases.

    PubMed

    Ba-Ssalamah, Ahmed; Zacherl, Johannes; Noebauer-Huhmann, Iris Melanie; Uffmann, Martin; Matzek, Wolfgang Karl; Pinker, Katja; Herold, Christian; Schima, Wolfgang

    2009-01-01

    Multi-detector computed tomography (CT) offers new opportunities in the imaging of the gastrointestinal tract. Its ability to cover a large volume in a very short scan time, and in a single breath hold with thin collimation and isotropic voxels, allows the imaging of the entire esophagus with high-quality multiplanar reformation and 3D reconstruction. Proper distention of the esophagus and stomach (by oral administration of effervescent granules and water) and optimally timed administration of intravenous contrast material are required to detect and characterize disease. In contrast to endoscopy and double-contrast studies of the upper GI tract, CT provides information about both the esophageal wall and the extramural extent of disease. Preoperative staging of esophageal carcinoma appears to be the main indication for MDCT. In addition, MDCT allows detection of other esophageal malignancies, such as lymphoma and benign esophageal tumors, such as leiomyma. A diagnosis of rupture or fistula of the esophagus can be firmly established using MDCT. Furthermore, miscellaneous esophageal conditions, such as achalasia, esophagitis, diverticula, and varices, are incidental findings and can also be visualized with hydro-multi-detector CT. Multi-detector CT is a valuable tool for the evaluation of esophageal wall disease and serves as an adjunct to endoscopy.

  18. SU-E-I-23: A General KV Constrained Optimization of CNR for CT Abdominal Imaging

    SciTech Connect

    Weir, V; Zhang, J

    2015-06-15

    Purpose: While Tube current modulation has been well accepted for CT dose reduction, kV adjusting in clinical settings is still at its early stage. This is mainly due to the limited kV options of most current CT scanners. kV adjusting can potentially reduce radiation dose and optimize image quality. This study is to optimize CT abdomen imaging acquisition based on the assumption of a continuous kV, with the goal to provide the best contrast to noise ratio (CNR). Methods: For a given dose (CTDIvol) level, the CNRs at different kV and pitches were measured with an ACR GAMMEX phantom. The phantom was scanned in a Siemens Sensation 64 scanner and a GE VCT 64 scanner. A constrained mathematical optimization was used to find the kV which led to the highest CNR for the anatomy and pitch setting. Parametric equations were obtained from polynomial fitting of plots of kVs vs CNRs. A suitable constraint region for optimization was chosen. Subsequent optimization yielded a peak CNR at a particular kV for different collimations and pitch setting. Results: The constrained mathematical optimization approach yields kV of 114.83 and 113.46, with CNRs of 1.27 and 1.11 at the pitch of 1.2 and 1.4, respectively, for the Siemens Sensation 64 scanner with the collimation of 32 x 0.625mm. An optimized kV of 134.25 and 1.51 CNR is obtained for a GE VCT 64 slice scanner with a collimation of 32 x 0.625mm and a pitch of 0.969. At 0.516 pitch and 32 x 0.625 mm an optimized kV of 133.75 and a CNR of 1.14 was found for the GE VCT 64 slice scanner. Conclusion: CNR in CT image acquisition can be further optimized with a continuous kV option instead of current discrete or fixed kV settings. A continuous kV option is a key for individualized CT protocols.

  19. Biofeasibility Study.

    ERIC Educational Resources Information Center

    Chaparian, Michael

    1995-01-01

    Discusses the use of bioremediation as a method for disposing of contaminants by exploiting natural biodegradation processes. The process of conducting a biofeasibility study and a case study are reviewed. (LZ)

  20. Cystometric study

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003904.htm Cystometric study To use the sharing features on this page, please enable JavaScript. Cystometric study measures the amount of fluid in the bladder ...

  1. Intelligence Studies

    ERIC Educational Resources Information Center

    Monaghan, Peter

    2009-01-01

    To make an academic study of matters inherently secret and potentially explosive seems a tall task. But a growing number of scholars are drawn to understanding spycraft. The interdisciplinary field of intelligence studies is mushrooming, as scholars trained in history, international studies, and political science examine such subjects as the…

  2. Religious Studies.

    ERIC Educational Resources Information Center

    Mohrman, Kathryn, Ed.

    1980-01-01

    An essay on the study of religion at the college level and descriptions of nine programs of religious studies are presented. The essay by David C. Smith suggests that while traditional goals continue to be important, especially in church-related colleges, religious studies has expanded to include insights and materials from such disciplines as…

  3. College Studying.

    ERIC Educational Resources Information Center

    Nist, Sherrie L.; Simpson, Michele

    2002-01-01

    Notes that many students enter postsecondary institutions unprepared to meet the studying demands placed on them. Examines models and taxonomies that have guided researchers as they have investigated studying. Reviews research factors related to studying at the college level: course characteristics, learner characteristics, and learning…

  4. Social Studies.

    ERIC Educational Resources Information Center

    Bieber, Edward

    The product of a Special Studies Institute, this teacher developed resource guide for the emotionally handicapped (K-6) presents social study concepts and activities relative to education in the urban out-of-doors. Focus is on the study of man (past, present, and future) interacting with his environment. Listed below are activity examples: (1)…

  5. Validation of multi-detector computed tomography as a non-invasive method for measuring ovarian volume in macaques (Macaca fascicularis).

    PubMed

    Jones, Jeryl C; Appt, Susan E; Werre, Stephen R; Tan, Joshua C; Kaplan, Jay R

    2010-06-01

    The purpose of this study was to validate low radiation dose, contrast-enhanced, multi-detector computed tomography (MDCT) as a non-invasive method for measuring ovarian volume in macaques. Computed tomography scans of four known-volume phantoms and nine mature female cynomolgus macaques were acquired using a previously described, low radiation dose scanning protocol, intravenous contrast enhancement, and a 32-slice MDCT scanner. Immediately following MDCT, ovaries were surgically removed and the ovarian weights were measured. The ovarian volumes were determined using water displacement. A veterinary radiologist who was unaware of actual volumes measured ovarian CT volumes three times, using a laptop computer, pen display tablet, hand-traced regions of interest, and free image analysis software. A statistician selected and performed all tests comparing the actual and CT data. Ovaries were successfully located in all MDCT scans. The iliac arteries and veins, uterus, fallopian tubes, cervix, ureters, urinary bladder, rectum, and colon were also consistently visualized. Large antral follicles were detected in six ovaries. Phantom mean CT volume was 0.702+/-SD 0.504 cc and the mean actual volume was 0.743+/-SD 0.526 cc. Ovary mean CT volume was 0.258+/-SD 0.159 cc and mean water displacement volume was 0.257+/-SD 0.145 cc. For phantoms, the mean coefficient of variation for CT volumes was 2.5%. For ovaries, the least squares mean coefficient of variation for CT volumes was 5.4%. The ovarian CT volume was significantly associated with actual ovarian volume (ICC coefficient 0.79, regression coefficient 0.5, P=0.0006) and the actual ovarian weight (ICC coefficient 0.62, regression coefficient 0.6, P=0.015). There was no association between the CT volume accuracy and mean ovarian CT density (degree of intravenous contrast enhancement), and there was no proportional or fixed bias in the CT volume measurements. Findings from this study indicate that MDCT is a valid non

  6. Micro-CT vs. Whole Body Multirow Detector CT for Analysing Bone Regeneration in an Animal Model

    PubMed Central

    Bissinger, Oliver; Kirschke, Jan S.; Probst, Florian Andreas; Stauber, Martin; Wolff, Klaus-Dietrich; Haller, Bernhard; Götz, Carolin; Plank, Christian; Kolk, Andreas

    2016-01-01

    Objectives Compared with multirow detector CT (MDCT), specimen (ex vivo) micro-CT (μCT) has a significantly higher (~ 30 x) spatial resolution and is considered the gold standard for assessing bone above the cellular level. However, it is expensive and time-consuming, and when applied in vivo, the radiation dose accumulates considerably. The aim of this study was to examine whether the lower resolution of the widely used MDCT is sufficient to qualitatively and quantitatively evaluate bone regeneration in rats. Methods Forty critical-size defects (5mm) were placed in the mandibular angle of rats and covered with coated bioactive titanium implants to promote bone healing. Five time points were selected (7, 14, 28, 56 and 112 days). μCT and MDCT were used to evaluate the defect region to determine the bone volume (BV), tissue mineral density (TMD) and bone mineral content (BMC). Results MDCT constantly achieved higher BV values than μCT (10.73±7.84 mm3 vs. 6.62±4.96 mm3, p<0.0001) and consistently lower TMD values (547.68±163.83 mm3 vs. 876.18±121.21 mm3, p<0.0001). No relevant difference was obtained for BMC (6.48±5.71 mm3 vs. 6.15±5.21 mm3, p = 0.40). BV and BMC showed very strong correlations between both methods, whereas TMD was only moderately correlated (r = 0.87, r = 0.90, r = 0.68, p < 0.0001). Conclusions Due to partial volume effects, MDCT overestimated BV and underestimated TMD but accurately determined BMC, even in small volumes, compared with μCT. Therefore, if bone quantity is a sufficient end point, a considerable number of animals and costs can be saved, and compared with in vivo μCT, the required dose of radiation can be reduced. PMID:27880788

  7. Aerosal studies

    NASA Technical Reports Server (NTRS)

    Harris, F. S., Jr.

    1976-01-01

    Various methods of measuring aerosols were studied in terms of the best methods to use, the instruments or techniques actually employed, and those techniques applied in field measurements on air quality as influenced by rocket launch effluents, and in an urban environment. Further studies were initiated on the remote sensing of aerosols by satellites and the influence of aerosols on visibility. The characterization of aerosols by measurement of scattered light was studied on Mie theory calculations.

  8. Prognostic impact of coronary microcirculation abnormalities in systemic sclerosis: a prospective study to evaluate the role of non-invasive tests

    PubMed Central

    2013-01-01

    Introduction Microcirculation dysfunction is a typical feature of systemic sclerosis (SSc) and represents the earliest abnormality of primary myocardial involvement. We assessed coronary microcirculation status by combining two functional tests in SSc patients and estimating its impact on disease outcome. Methods Forty-one SSc patients, asymptomatic for coronary artery disease, were tested for coronary flow velocity reserve (CFR) by transthoracic-echo-Doppler with adenosine infusion (A-TTE) and for left ventricular wall motion abnormalities (WMA) by dobutamine stress echocardiography (DSE). Myocardial multi-detector computed tomography (MDCT) enabled the presence of epicardial stenosis, which could interfere with the accuracy of the tests, to be excluded. Patient survival rate was assessed over a 6.7- ± 3.5-year follow-up. Results Nineteen out of 41 (46%) SSc patients had a reduced CFR (≤2.5) and in 16/41 (39%) a WMA was observed during DSE. Furthermore, 13/41 (32%) patients showed pathological CFR and WMA. An inverse correlation between wall motion score index (WMSI) during DSE and CFR value (r = -0.57, P <0.0001) was observed; in addition, CFR was significantly reduced (2.21 ± 0.38) in patients with WMA as compared to those without (2.94 ± 0.60) (P <0.0001). In 12 patients with abnormal DSE, MDCT was used to exclude macrovasculopathy. During a 6.7- ± 3.5-year follow-up seven patients with abnormal coronary functional tests died of disease-related causes, compared to only one patient with normal tests. Conclusions A-TTE and DSE tests are useful tools to detect non-invasively pre-clinical microcirculation abnormalities in SSc patients; moreover, abnormal CFR and WMA might be related to a worse disease outcome suggesting a prognostic value of these tests, similar to other myocardial diseases. PMID:23302110

  9. Coronary CT angiography using 64 detector rows: methods and design of the multi-centre trial CORE-64

    PubMed Central

    Vavere, Andrea L.; Rochitte, Carlos E.; Niinuma, Hiroyuki; Arbab-Zadeh, Armin; Paul, Narinder; Hoe, John; de Roos, Albert; Yoshioka, Kunihiro; Lemos, Pedro A.; Bush, David E.; Lardo, Albert C.; Texter, John; Brinker, Jeffery; Cox, Christopher; Clouse, Melvin E.; Lima, João A. C.

    2012-01-01

    Multislice computed tomography (MSCT) for the noninvasive detection of coronary artery stenoses is a promising candidate for widespread clinical application because of its noninvasive nature and high sensitivity and negative predictive value as found in several previous studies using 16 to 64 simultaneous detector rows. A multi-centre study of CT coronary angiography using 16 simultaneous detector rows has shown that 16-slice CT is limited by a high number of nondiagnostic cases and a high false-positive rate. A recent meta-analysis indicated a significant interaction between the size of the study sample and the diagnostic odds ratios suggestive of small study bias, highlighting the importance of evaluating MSCT using 64 simultaneous detector rows in a multi-centre approach with a larger sample size. In this manuscript we detail the objectives and methods of the prospective “CORE-64” trial (“Coronary Evaluation Using Multidetector Spiral Computed Tomography Angiography using 64 Detectors”). This multi-centre trialwas unique in that it assessed the diagnostic performance of 64-slice CT coronary angiography in nine centres worldwide in comparison to conventional coronary angiography. In conclusion, the multi-centre, multi-institutional and multi-continental trial CORE-64 has great potential to ultimately assess the per-patient diagnostic performance of coronary CT angiography using 64 simultaneous detector rows. PMID:18998142

  10. Assessment of Radiation doses to Paediatric Patients in Computed Tomography Procedures

    PubMed Central

    Alzimami, Khalid

    2014-01-01

    Summary Background The use of pediatric CT that had recently emerged as a valuable imaging tool has increased rapidly with an annual growth estimated at about 10% per year. Worldwide, there is a remarkable increase in the number of CT examinations performed. The purposes of this study are to: (i) to measure the radiation dose and estimate the effective doses to pediatric patients during CT for chest, abdomen and brain. Material/Methods A total of 182 patients were investigated. CT scanners that participated in this study are helical CT scanners (64 slices, 16 slices and dual slices). Organ and surface dose to specific radiosensitive organs were estimated by using software from National Radiological Protection Board (NRPB). Results For all patients, the age was ranged between 1.12 month–10.0 years while the weight was ranged between 5.0 kg to 29.0 kg. The DLP was 320.58 mGy·cm, 79.93 mGy·cm, 66.63 mGy·cm for brain, abdomen and chest respectively. The effective dose was, 2.05, 1.8, 1.08 mSv for brain, abdomen and chest respectively. Conclusions The patient dose is independent of CT modality and depends on operator experience and CT protocol. The study has shown a great need for referring criteria, continuous training of staff in radiation protection concepts. Further studies are required in order to establish a reference level in Sudan. PMID:25289112

  11. Studying Zooarchaeology

    ERIC Educational Resources Information Center

    Moore, Molly; Wolf, Deborah; Butler, Virginia L.

    2012-01-01

    Children often associate the study of bones with dinosaurs or crime scenes. This unit introduces students to "zooarchaeology," the study of animal remains from archaeological sites. Students in grades 3-5 engage in hands-on activities examining bones, shells, and other "hard parts" of animals. They use their observations as a starting point for…

  12. Study Carrels

    ERIC Educational Resources Information Center

    Training, 1977

    1977-01-01

    Information on various study carrels to provide individualized learning space for training use is presented. It is noted that carrels may be standard models or customized, and most are wired for audiovisual equipment. A list of study carrel suppliers and manufacturers is included. (MF)

  13. Stream Studies.

    ERIC Educational Resources Information Center

    Hamilton City Board of Education (Ontario).

    This manual provides teachers with some knowledge of ecological study methods and techniques used in collecting data when plants and animals are studied in the field. Most activities deal with the interrelatedness of plant and animal life to the structure and characteristics of a stream and pond. Also included in this unit plan designed for the…

  14. Bird Study

    ERIC Educational Resources Information Center

    Katz, Margaret

    1978-01-01

    Excerpts from a first grade teacher's diary describe bird study activities done by the class over a two week period. Each student studied a bird of their choice in detail and made a papier-mache model of the bird. These models were exhibited at a student initiated program for visitors. (MA)

  15. Women's Studies.

    ERIC Educational Resources Information Center

    Davis, James E., Ed.; Davis, Hazel K., Ed.

    1981-01-01

    The 16 articles in this journal issue deal with women's studies within the English curriculum. Topics discussed in the articles include (1) the feminist challenge to the male-centered curriculum in higher education; (2) the women's movement and women's studies; (3) connotations of the word "girl"; (4) women in English education; (5) the new…

  16. Social Studies.

    ERIC Educational Resources Information Center

    White, Cam, Ed.

    This document contains the following papers on social studies instruction and technology: (1) "Waking the Sleeping Giant: Social Studies Teacher Educators Collaborate To Integrate Technology into Methods' Courses" (Cheryl Mason, Marsha Alibrandi, Michael Berson, Kara Dawson, Rich Diem, Tony Dralle, David Hicks, Tim Keiper, and John Lee);…

  17. Culture Studies: Hawaiian Studies Project.

    ERIC Educational Resources Information Center

    Hazama, Dorothy, Ed.

    Reports and materials from the Hawaiian Studies Project are presented. The document, designed for elementary school teachers contains two major sections. The first section describes the planning phase of the project, the Summer Institute for Hawaiian Culture Studies (1976) and the follow-up workshops and consultant help (1976-77). The appendix to…

  18. RELATION OF LEFT VENTRICULAR MASS AND CONCENTRIC REMODELING TO EXTENT OF CORONARY ARTERY DISEASE BY COMPUTED TOMOGRAPHY IN PATIENTS WITHOUT LEFT VENTRICULAR HYPERTROPHY: ROMICAT STUDY

    PubMed Central

    Truong, Quynh A.; Toepker, Michael; Mahabadi, Amir A.; Bamberg, Fabian; Rogers, Ian S.; Blankstein, Ron; Brady, Thomas J.; Nagurney, John T.; Hoffmann, Udo

    2010-01-01

    Objective Cardiac computed tomography (CT) allows for simultaneous assessment of left ventricular mass (LVM) and coronary artery disease (CAD). We aimed to determine whether LVM, LVM index (LVMi), and the left ventricular (LV) geometric pattern of concentric remodeling are associated with the extent of CAD in patients without left ventricular hypertrophy (LVH). Methods In 348 patients from the ROMICAT trial, 64-slice CT was performed and LVM measured at end-diastole. We used 3 LVM indexation criteria to obtain 3 cohorts: LVM indexed to body surface area by echocardiography (n=337) and CT criteria (n=325), and by height2.7 (n=326). The cohorts were subdivided into concentric remodeling and normal geometry. Extent of coronary plaque was classified based on a 17-segment model, treated as a continuous variable, and stratified into 3 groups: 0 segments, 1–4 segments, >4 segments. Results Patients with >4 segments of coronary plaque had higher LVM (Δ12.8–15.1g) and LVMi (Δ4.0–5.5g/m2 and Δ2.2g/m2.7) than those without CAD (all p≤0.03). After multivariable adjustment, LVM and LVMi remained independent predictors of extent of coronary plaque, with 0.27–0.29 segments more plaque per 20 g increase of LVM (all p=0.02), 0.32–0.34 segments more plaque per 10 g/m2 increase of LVMi (both p=0.02), and 0.80 segments more plaque per 10 g/m2.7 increase of LVMi (p=0.008). Concentric remodeling patients had 1.1–1.3 segments more plaque than those with normal geometry (all p≤0.05). Patients with >4 segments of plaque had 2-fold increase odds (all p≤0.05) of having concentric remodeling as compared to those without CAD. Conclusion Increased LVM, LVMi, and concentric remodeling are associated with a greater degree of coronary plaque burden in patients without LVH. These findings could provide an indication to intensify medical therapy in patients with subclinical CAD and hypertension. PMID:19696685

  19. Influence of increased epicardial adipose tissue volume on 1-year in-stent restenosis in patients who received coronary stent implantation

    PubMed Central

    Zhou, Ying; Zhang, Hua-Wei; Tian, Feng; Chen, Jin-Song; Han, Tian-Wen; Tan, Ya-Hang; Zhou, Jia; Zhang, Tao; Jing, Jing; Chen, Yun-Dai

    2016-01-01

    Background Epicardial adipose tissue (EAT) is significantly associated with the formation and composition of coronary atherosclerotic plaque, cardiac events and the clinical prognosis of coronary heart disease. But, whether increased EAT deposition may affect the incidence of in-stent restenosis (ISR) is currently unclear. This study used coronary computed tomography angiography (CCTA) as a mean to investigate whether increased EAT volume was associated with ISR. Methods A total of 364 patients who underwent 64-slice CCTA examination for the evaluation of suspected coronary artery disease, and subsequently underwent percutaneous coronary intervention (PCI) for the first time, and then accepted coronary angiography (CA) follow-up for ISR examination in one year, were retrospectively included in this study. EAT volume was measured by CCTA examination. CA follow-up was obtained between 9 and 15 months. ISR was defined as ≥ 50% luminal diameter narrowing of the stent segment or peri-stent segment. EAT volume was compared between patients with and without ISR and additional well-known predictors of ISR were compared. Results EAT volume was significantly increased in patients with ISR compared with those without ISR (154.5 ± 74.6 mL vs. 131.0 ± 52.2 mL, P < 0.001). The relation between ISR and EAT volume remained significant after adjustment for conventional cardiovascular risk factors and angiographic parameters. Conclusions EAT volume was related with ISR and may provide additional information for future ISR. PMID:27899941

  20. Relevance of MTF and NPS in quantitative CT: towards developing a predictable model of quantitative performance

    NASA Astrophysics Data System (ADS)

    Chen, Baiyu; Richard, Samuel; Samei, Ehsan

    2012-03-01

    The quantification of lung nodule volume based on CT images provides valuable information for disease diagnosis and staging. However, the precision of the quantification is protocol, system, and technique dependent and needs to be evaluated for each specific case. To efficiently investigate the quantitative precision and find an optimal operating point, it is important to develop a predictive model based on basic system parameters. In this study, a Fourier-based metric, the estimability index (e') was proposed as such a predictor, and validated across a variety of imaging conditions. To first obtain the ground truth of quantitative precision, an anthropomorphic chest phantom with synthetic spherical nodules were imaged on a 64 slice CT scanner across a range of protocols (five exposure levels and two reconstruction algorithms). The volumes of nodules were quantified from the images using clinical software, with the precision of the quantification calculated for each protocol. To predict the precision, e' was calculated for each protocol based on several Fourier-based figures of merit, which modeled the characteristic of the quantitation task and the imaging condition (resolution, noise, etc.) of a particular protocol. Results showed a strong correlation (R2=0.92) between the measured and predicted precision across all protocols, indicating e' as an effective predictor of the quantitative precision. This study provides a useful framework for quantification-oriented optimization of CT protocols.

  1. Considerations on an automatic computed tomography tube current modulation system.

    PubMed

    Moro, Luca; Panizza, Denis; D'Ambrosio, Daniela; Carne, Irene

    2013-10-01

    The scope of this study was to evaluate the effects on radiation output and image noise varying the acquisition parameters with an automatic tube current modulation (ATCM) system in computed tomography (CT). Chest CT examinations of an anthropomorphic phantom were acquired using a GE LightSpeed VCT 64-slice tomograph. Acquisitions were performed using different pitch, slice thickness and noise index (NI) values and varying the orientation of the scanned projection radiograph (SPR). The radiation output was determined by the CT dose index (CTDIvol). Image noise was evaluated measuring the standard deviation of CT numbers in several regions of interest. The radiation output was lower if the SPR was acquired in the anterior-posterior projection. The radiation dose with the posterior-anterior SPR was higher, because the divergence of the X-ray beam magnifies the anatomical structures closest to the tube, especially the spinal column, and this leads the ATCM system to estimate higher patient attenuation values and, therefore, to select higher tube current values. The NI was inversely proportional to the square root of the CTDIvol and, with fixed NI, the CTDIvol increased as the slice thickness decreased. This study suggests some important issues to use the GE ATCM system efficiently.

  2. Research Study

    ERIC Educational Resources Information Center

    Glick, Ashley

    2010-01-01

    Background: Action Research about my 2nd grade classroom in the Buffalo School District. I examined three areas of interest and tried to find some conclusions related to behavior management. Purpose: The purpose of this study is how will implementing procedures, rules, and consequences help improve student behavior. Research Design: Descriptive;…

  3. MEDIEVAL STUDIES.

    ERIC Educational Resources Information Center

    MARTONFFY, ANDREA PONTECORVO; AND OTHERS

    A CURRICULUM GUIDE ON MEDIEVAL STUDIES IS PRESENTED, INCLUDING TEACHER MATERIALS AND STUDENT PROBLEM SETS. THE TEACHER MATERIALS DESCRIBE AND EXPLAIN THE ECONOMIC, SOCIAL, AND POLITICAL ASPECTS OF MANORIAL LIFE--THE PREDOMINANT FORM OF AGRICULTURAL LIFE IN NORTHERN FRANCE, ENGLAND, AND GERMANY DURING THE PERIOD FROM APPROXIMATELY 800 TO 1300 A.D.…

  4. Case Studies

    ERIC Educational Resources Information Center

    Ritter, Lois A., Ed.; Sue, Valerie M., Ed.

    2007-01-01

    This article presents two case studies using online surveys for evaluation. The authors begin with an example of a needs assessment survey designed to measure the amount of help new students at a university require in their first year. They then discuss the follow-up survey conducted by the same university to measure the effectiveness of the…

  5. Three-dimensional models: an emerging investigational revolution for craniovertebral junction surgery.

    PubMed

    Goel, Atul; Jankharia, Bhavin; Shah, Abhidha; Sathe, Prashant

    2016-12-01

    Complex craniovertebral junctional anomalies can be daunting to treat surgically, and preoperative information regarding the osseous abnormalities, course of the vertebral arteries, size of the pedicles, and location of the transverse foramina is invaluable to surgeons operating on these challenging cases. The authors present their experience with the emerging technology of 3D model acquisition for surgery in 11 cases of complex craniovertebral junction region anomalies. For each case, a 3D printed model was made from thin CT scans using a 64-slice CT scanner. The inclination of the joints, the presence of false articulations, the size of the pedicles, and the course of the vertebral arteries were studied preoperatively on the 3D models. The sizes of the plates and screws to be used and the angle of insertion of the screws were calculated based on the data from the models. The model was scaled to actual size and was kept beside the operating surgeon in its anatomical position during surgery. The potential uses of the models and their advantages over conventional radiological investigations are discussed. The authors conclude that 3D models can be an invaluable aid during surgery for complex craniovertebral junction anomalies. The information available from a real life-size model supersedes the information available from 3D CT reconstructions and can also be superior to virtual simulation. The models are both cost effective and easy to build and the authors suggest that they may form the basis of investigations in the near future for craniovertebral junction surgery.

  6. SU-E-P-11: Comparison of Image Quality and Radiation Dose Between Different Scanner System in Routine Abdomen CT

    SciTech Connect

    Liao, S; Wang, Y; Weng, H

    2015-06-15

    Purpose To evaluate image quality and radiation dose of routine abdomen computed tomography exam with the automatic current modulation technique (ATCM) performed in two different brand 64-slice CT scanners in our site. Materials and Methods A retrospective review of routine abdomen CT exam performed with two scanners; scanner A and scanner B in our site. To calculate standard deviation of the portal hepatic level with a region of interest of 12.5 mm x 12.5mm represented to the image noise. The radiation dose was obtained from CT DICOM image information. Using Computed tomography dose index volume (CTDIv) to represented CT radiation dose. The patient data in this study were with normal weight (about 65–75 Kg). Results The standard deviation of Scanner A was smaller than scanner B, the scanner A might with better image quality than scanner B. On the other hand, the radiation dose of scanner A was higher than scanner B(about higher 50–60%) with ATCM. Both of them, the radiation dose was under diagnostic reference level. Conclusion The ATCM systems in modern CT scanners can contribute a significant reduction in radiation dose to the patient. But the reduction by ATCM systems from different CT scanner manufacturers has slightly variation. Whatever CT scanner we use, it is necessary to find the acceptable threshold of image quality with the minimum possible radiation exposure to the patient in agreement with the ALARA principle.

  7. The influence of tube voltage and phantom size in computed tomography on the dose-response relationship of dicentrics in human blood samples

    NASA Astrophysics Data System (ADS)

    Jost, G.; Lengsfeld, P.; Voth, M.; Schmid, E.; Pietsch, H.

    2010-06-01

    The aim of this study was to investigate the dose response relationship of dicentrics in human lymphocytes after CT scans at tube voltages of 80 and 140 kV. Blood samples from a healthy donor placed in tissue equivalent abdomen phantoms of standard, pediatric and adipose sizes were exposed at dose levels up to 0.1 Gy using a 64-slice CT scanner. It was found that both the tube voltage and the phantom size significantly influenced the CT scan-induced linear dose-response relationship of dicentrics in human lymphocytes. Using the same phantom (standard abdomen), 80 kV CT x-rays were biologically more effective than 140 kV CT x-rays. However, it could also be determined that the applied phantom size had much more influence on the biological effectiveness. Obviously, the increasing slopes of the CT scan-induced dose response relationships of dicentrics in human lymphocytes obtained in a pediatric, a standard and an adipose abdomen have been induced by scattering effects of photons, which strongly increase with increasing phantom size.

  8. Visualisation of the Bonebridge by means of CT and CBCT

    PubMed Central

    2013-01-01

    Background With the Bonebridge, a new bone-anchored hearing aid has been available since March 2012. The objective of the study was to analyse the visualisation of the implant itself as well as its impact on the representation of the bony structures of the petrosal bone in CT, MRI and cone beam CT (CBCT). Methods The Bonebridge was implanted unilaterally in two completely prepared human heads. The radiological imaging by means of CBCT, 64-slice CT, 1.5-T and 3.0-T MRI was conducted both preoperatively and postoperatively. The images were subsequently evaluated from both the ENT medical and nd radiological perspectives. Results As anticipated, no visualisation of the implant or of the petrosal bones could be realised on MRI because of the interactive technology and the magnet artefact. In contrast, an excellent evaluability of the implant itself as well as of the surrounding neurovascular structures (sinus sigmoideus, skull base, middle ear, inner ear, inner auditory canal) was exhibited in both the CT and in the CBCT. Conclusion The Bonebridge can be excellently imaged with the radiological imaging technologies of CT and CBCT. In the process, CBCT shows discrete advantages in comparison with CT. No relevant restrictions in image quality in the evaluation of the bony structures of the petrosal bones could be seen. PMID:24004903

  9. Trapping volumetric measurement by multidetector CT in chronic obstructive pulmonary disease: Effect of CT threshold

    SciTech Connect

    Wang, Xiaohua; Yuan, Huishu; Duan, Jianghui; Du, Yipeng; Shen, Ning; He, Bei

    2013-08-15

    Purpose: The purpose of this study was to evaluate the effect of various computed tomography (CT) thresholds on trapping volumetric measurements by multidetector CT in chronic obstructive pulmonary disease (COPD).Methods: Twenty-three COPD patients were scanned with a 64-slice CT scanner in both the inspiratory and expiratory phase. CT thresholds of −950 Hu in inspiration and −950 to −890 Hu in expiration were used, after which trapping volumetric measurements were made using computer software. Trapping volume percentage (Vtrap%) under the different CT thresholds in the expiratory phase and below −950 Hu in the inspiratory phase was compared and correlated with lung function.Results: Mean Vtrap% was similar under −930 Hu in the expiratory phase and below −950 Hu in the inspiratory phase, being 13.18 ± 9.66 and 13.95 ± 6.72 (both lungs), respectively; this difference was not significant (P= 0.240). Vtrap% under −950 Hu in the inspiratory phase and below the −950 to −890 Hu threshold in the expiratory phase was moderately negatively correlated with the ratio of forced expiratory volume in one second to forced vital capacity and the measured value of forced expiratory volume in one second as a percentage of the predicted value.Conclusions: Trapping volumetric measurement with multidetector CT is a promising method for the quantification of COPD. It is important to know the effect of various CT thresholds on trapping volumetric measurements.

  10. Cholera studies*

    PubMed Central

    Pollitzer, R.

    1956-01-01

    The first portion of this study describes in detail the different aspects of stool examinations, including the collection, preservation, and pooling of specimens, macroscopic and bacterioscopic examination, enrichment methods, and cultivation on a variety of solid media. The author also deals with the examination of vomits and of water. The performance and value of different identification tests (agglutination, haemolysis, and bacteriophage) and confirmatory tests are then considered. An annex is included on bacteriological procedures in the laboratory diagnosis of cholera. PMID:13356145

  11. Thalidomide study.

    PubMed

    1997-07-01

    Preliminary findings from a study on the effects of thalidomide on HIV-related wasting syndrome are encouraging. The study shows that at least half of the weight gained by participants was in the form of lean body mass. Side effects included declines in neutrophil counts and pain or tingling in the hands and/or feet. A 0.3 log increase in viral load and no decrease in TNF-alpha levels were also noted. Celgene, the manufacturer of thalidomide, has streamlined an expanded access program and fully covers the cost of the drug for people who qualify for the program. (A phone number is provided for more information.) Additionally, the company is studying the benefits of thalidomide treatment for oral and esophageal aphthous ulcers. Results from the use of three different doses following four weeks will be compared, after which patients will be randomly assigned to either a placebo or thalidomide to determine its ability to prevent a relapse. Because of thalidomide's connection to serious birth defects, it is important that men and women engaging in reproductive sex use precautions to prevent pregnancy.

  12. Anticorrosion studies

    NASA Technical Reports Server (NTRS)

    Boerio, J.

    1986-01-01

    The aging behavior of chemically bonded interfaces between metals and pottants, such as ethylene vinyl acetate (EVA) was studied using the Dow Corning primer systems. It was observed that the primers seem to function as anticorrosive agents on metal surfaces. It was demonstrated that EVA, and the A-11861 EVA/glass primer stops corrosion of the aluminum used on the back surfaces of crystalline silicon solar cells. However, this same treatment does not work for the aluminum on the back surfaces of amorphous silicon solar cells.

  13. Cholera studies*

    PubMed Central

    Swaroop, S.; Pollitzer, R.

    1955-01-01

    In this study, figures relating to cholera deaths occurring in individual countries, from 1900 to 1952, are recorded as well as the incidence of the disease from 1923 up to the present time. The mode of spread of cholera from its endemic home in India to outside countries is described in relation to favourable seasons, main routes followed by the infection, and the role played by large religious gatherings. The incidence of the disease in the various seaports infected within recent years is discussed. PMID:14364186

  14. Plague studies*

    PubMed Central

    Pollitzer, R.

    1953-01-01

    In examining the control and prevention of plague, the author pays particular attention to the control of commensal rodents and their fleas. The various rat poisons in current use, their efficacy and practical application, and the dangers involved in their manipulation are described in great detail. The author also discusses other anti-rodent measures such as fumigation, rat-proofing, sanitation, protection of food, etc. The second part of the study deals with: vector control—the outstanding value of DDT application in rodent-flea control is emphasized—, the direct control of bubonic and pneumonic plague, and the control of the spread of plague at a distance. PMID:20603968

  15. Cholera studies*

    PubMed Central

    Pollitzer, R.

    1957-01-01

    Discussing the symptomatology of cholera, the author deals first with the incubation period, the clinical types, choleraic diarrhoea, and cholerine; he then considers in detail the various stages of cholera gravis and the relapses and complications that may be met. This is followed by sections on diagnosis and differential diagnosis, and on prognosis and the various factors influencing it. The author's highly detailed review of the treatment of cholera which concludes this study is divided into three parts, dealing with attempts at specific therapy, with infusion treatment, and with adjuvant treatment. PMID:13426761

  16. Plague studies*

    PubMed Central

    Pollitzer, R.

    1953-01-01

    Epidemiological aspects of (a) bubonic plague and (b) primary pneumonic plague are discussed separately in this study. The cause, spread, and persistence of bubonic outbreaks are dealt with. In the case of primary pneumonic plague, the author systematically reviews the factors influencing the spread of the disease: climatic and social conditions, infectivity of the patients, immunity, and control measures. In discussing the cause of pneumonic plague outbreaks, the author deals with the possible influence of a special virulence of pneumonic strains, the role of the rodent and flea species involved, and the possibility of a pneumotropismus acquired by Pasteurella pestis. The periodicity (cyclical and secular) of bubonic plague epidemics is discussed with a view to the possible forecasting of future epidemics. The author indicates the influence of race, age, sex, and occupation on the incidence of both forms of the disease. PMID:13082391

  17. Nutritional studies

    NASA Technical Reports Server (NTRS)

    Rambaut, P. C.; Smith, M. C., Jr.; Wheeler, H. O.

    1975-01-01

    Detailed metabolic studies were conducted of the Apollo 16 and Apollo 17 flight crews, and the results are presented in tabular form. Intake and absorption data are also included. Apollo nutrient intakes were found to be characteristically hypocaloric. Estimates of body composition changes from metabolic balance data, from preflight and postflight weights and volumes, and from total body water and potassium provide no evidence for diminished caloric requirements during a flight. As observed during the Gemini Program and during periods of bed rest, measurements of bone density and metabolic balance confirm a tendency toward loss of skeletal tissue in weightlessness. No evidence exists that any inflight metabolic anomaly, including hypokalemia, was induced by marginal or deficient nutrient intakes. In general, the Apollo crewmen were well nourished and exhibited normal gastroenterological functions, although appetite was somewhat diminished and the organoleptic response to food was somewhat modified during flight.

  18. Cholera studies*

    PubMed Central

    Pollitzer, R.

    1957-01-01

    The first section of this study deals with areas where cholera is endemic and with the conditions normally favouring endemicity. Turning next to epidemics, the author discusses their origin and types, climatic influences on them, their periodicity and the possibility of forecasting them, the role played in them by different serological races of V. cholerae, and the causes of their decline. In a section on the factors governing the local spread of cholera, he considers contact and water-borne infection; the role of contaminated food and drink, of fomites, of flies, and of carriers; and the incidence according to sex, age, race, and occupation. The last part deals with factors governing the spread of cholera over longer distances, and includes discussion of the effect of movements of individuals and groups and of assemblies of the population on pilgrimages or at religious festivals. PMID:13472431

  19. Cholera studies*

    PubMed Central

    Pollitzer, R.

    1957-01-01

    In discussing prevention, the author deals first with the provision of permanently safe water, supplied from waterworks or wells, and with other improvements in environmental sanitation. Control of food and drinks, public health propaganda and education, and vaccination are also considered under this heading. The greater part of this study is devoted to suppressive measures, affecting the individual, the environment, and persons in the mass. Discussion of the isolation, detection and management of cholera patients, the management of contacts, and the management and treatment of carriers is followed by sections on, inter alia, disinfection, temporary improvements in water supplies, fly control, and personal prophylaxis. In dealing with mass prophylaxis, the author pays particular attention to vaccination. In the concluding sections he goes into the control of pilgrimages and local and international quarantine measures. PMID:13479774

  20. Plague studies*

    PubMed Central

    Pollitzer, R.

    1953-01-01

    The author examines in detail the symptomatology, diagnosis, and treatment of plague, and outlines the problem of the length of the incubation period. The clinical features commonly met with in all severely-affected plague patients, regardless of the primary localization of the infection, are described. The author then deals with the symptomatology and manifestations of bubonic plague as compared to those of primary pneumonic plague. The importance of a clinical diagnosis, from the point of view of prevention, is stressed, and the differential diagnosis of various forms of the disease is described. The study contains a detailed discussion of the respective merits of antibiotic treatment, serotherapy, and sulfonamide treatment. The author points out that the outstanding success of streptomycin and some other antibiotics will probably relegate the sulfonamides to the second rank in the treatment of bubonic plague. PMID:13082390

  1. [EPINETAC study].

    PubMed

    Hernández Navarrete, Ma Jesús; Arribas Llorente, José Luis; Misiego Peral, Antonio; Guillamón, Inmaculada

    2006-02-01

    Daily, health professionals face biological risks, which have important repercussions for their own health, while performing their professional duties. A system which records data that quantifies and specifies the causes of work place accidents, the instruments most frequently involved in accidents, the professional categories having the greatest exposure, the tasks most at risk and the types of lesions is fundamental in order to grasp the true dimensions of these problems related to accidents and serum-borne disease transmission. Such a data base-could lead to the necessity, and highlight the importance, to increase preventive and protective measures for health personnel. To meet this objective, the EPINETAC project has been developed thanks to the information provided by 106 centers having various degrees of participation during the different years this study has taken.

  2. Systems Studies

    SciTech Connect

    Graham, R.L.

    1998-03-17

    The Systems Studies Activity had two objectives: (1) to investigate nontechnical barriers to the deployment of biomass production and supply systems and (2) to enhance and extend existing systems models of bioenergy supply and use. For the first objective, the Activity focused on existing bioenergy markets. Four projects were undertaken: a comparative analysis of bioenergy in Sweden and Austria; a one-day workshop on nontechnical barriers jointly supported by the Production Systems Activity; the development and testing of a framework for analyzing barriers and drivers to bioenergy markets; and surveys of wood pellet users in Sweden, Austria and the US. For the second objective, two projects were undertaken. First, the Activity worked with the Integrated BioEnergy Systems (TBS) Activity of TEA Bioenergy Task XIII to enhance the BioEnergy Assessment Model (BEAM). This model is documented in the final report of the IBS Activity. The Systems Studies Activity contributed to enhancing the feedstock portion of the model by developing a coherent set of willow, poplar, and switchgrass production modules relevant to both the US and the UK. The Activity also developed a pretreatment module for switchgrass. Second, the Activity sponsored a three-day workshop on modeling bioenergy systems with the objectives of providing an overview of the types of models used to evaluate bioenergy and promoting communication among bioenergy modelers. There were nine guest speakers addressing different types of models used to evaluate different aspects of bioenergy, ranging from technoeconomic models based on the ASPEN software to linear programming models to develop feedstock supply curves for the US. The papers from this workshop have been submitted to Biomass and Bioenergy and are under editorial review.

  3. Studying toxicity

    USGS Publications Warehouse

    Elkus, A.; LeBlanc, L.; Kim, C.; Van Beneden, R.; Mayer, G.

    2006-01-01

    With funding from the George Mitchell Center for the Environment at the University of Maine, a team of scientists used a simple laboratory-based sediment resuspension design, and two well-established aquatic toxicology models, fathead minnows (Pimephales promelas) and zebrafish (Danio rerio), to evaluate if resuspension of Penobscot river sediment significantly elevates the toxicity of river water and to provide preliminary information on the types of chemicals likely to desorb during resuspension. The group collected sediments from two sites with known chemical contamination downstream of the Great Works and Veazie dams. The sediments were examined to determine the dynamics of PAH desorption and degradation under different resuspension frequencies. The scientists used clarified water from resuspension experiments for toxicity tests with the water-flea Ceriodaphnia dubia, and other aquatic test organisms to infer toxicity from sediments from northern California rivers. Data from the study will help ascertain whether metals and/or xenoestrogens are present in the desorption water and give insight into possible avenues of sediment remediation.

  4. Extracorporeal Gas Exchange and Spontaneous Breathing for the Treatment of Acute Respiratory Distress Syndrome: An Alternative to Mechanical Ventilation?

    DTIC Science & Technology

    2014-03-01

    PV) curves were obtained, as previously described (21), starting from functional residual capacity. Chest CT (Toshiba Aquilion 64-slice Medical...close to the one recorded in static conditions in healthy animals when inflating the lung from functional residual capacity to total lung capacity...Clinical Director, Maquet Cardiovascular Global) and Brian Osswald (Vice President, Maquet Cardiopulmonary , USA) for providing the Cardiohelp and

  5. RESPECT-ED: Rates of Pulmonary Emboli (PE) and Sub-Segmental PE with Modern Computed Tomographic Pulmonary Angiograms in Emergency Departments: A Multi-Center Observational Study Finds Significant Yield Variation, Uncorrelated with Use or Small PE Rates

    PubMed Central

    Chu, Kevin; Joseph, Anthony; Read, Catherine; Blecher, Gabriel; Furyk, Jeremy; Bharat, Chrianna; Velusamy, Karthik; Munro, Andrew; Baker, Kylie; Kinnear, Frances; Mukherjee, Ahses; Watkins, Gina; Buntine, Paul; Livesay, Georgia

    2016-01-01

    Introduction Overuse of CT Pulmonary Angiograms (CTPA) for diagnosing pulmonary embolism (PE), particularly in Emergency Departments (ED), is considered problematic. Marked variations in positive CTPA rates are reported, with American 4–10% yields driving most concerns. Higher resolution CTPA may increase sub-segmental PE (SSPE) diagnoses, which may be up to 40% false positive. Excessive use and false positives could increase harm vs. benefit. These issues have not been systematically examined outside America. Aims To describe current yield variation and CTPA utilisation in Australasian ED, exploring potential factors correlated with variation. Methods A retrospective multi-centre review of consecutive ED-ordered CTPA using standard radiology reports. ED CTPA report data were inputted onto preformatted data-sheets. The primary outcome was site level yield, analysed both intra-site and against a nominated 15.3% yield. Factors potentially associated with yield were assessed for correlation. Results Fourteen radiology departments (15 ED) provided 7077 CTPA data (94% ≥64-slice CT); PE were reported in 1028 (yield 14.6% (95%CI 13.8–15.4%; range 9.3–25.3%; site variation p <0.0001) with four sites significantly below and one above the 15.3% target. Admissions, CTPA usage, PE diagnosis rates and size of PE were uncorrelated with yield. Large PE (≥lobar) were 55% (CI: 52.1–58.2%) and SSPE 8.8% (CI: 7.1–10.5%) of positive scans. CTPA usage (0.2–1.5% adult attendances) was correlated (p<0.006) with PE diagnosis but not SSPE: large PE proportions. Discussion/ Conclusions We found significant intra-site CTPA yield variation within Australasia. Yield was not clearly correlated with CTPA usage or increased small PE rates. Both SSPE and large PE rates were similar to higher yield historical cohorts. CTPA use was considerably below USA 2.5–3% rates. Higher CTPA utilisation was positively correlated with PE diagnoses, but without evidence of increased proportions

  6. Multidetector Computed Tomography and Magnetic Resonance Imaging Evaluation of Craniovertebral junction Abnormalities

    PubMed Central

    Dhadve, Rajshree U.; Garge, Shaileshkumar S.; Vyas, Pooja D.; Thakker, Nirav R.; Shah, Sonali H.; Jaggi, Sunila T.; Talwar, Inder A.

    2015-01-01

    Background: Craniovertebral junction (CVJ) abnormalities constitute an important group of treatable neurological disorders with diagnostic dilemma. Their precise diagnosis, identification of probable etiology, and pretreatment evaluation significantly affects prognosis and quality of life of patients. Aims: The study was to classify various craniovertebral junction disorders according to their etiology and to define the importance of precise diagnosis for pretreatment evaluation with multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI). Materials and Methods: This is a prospective observational study of 62 patients referred to our department between October 2012 and September 2014. All patients suspected to have a craniovertebral junction disorder were included in the study, from all age groups and both genders. Detailed clinical history was taken. Radiographs of cervical spine were collected if available. All patients were subjected to MDCT and/or MRI. Results: In our study of 62 patients; 39 were males and 23 were females, with male to female ratio of 1.6:1. Most common age group was 2nd -3rd decade (19 patients, 30.64%). Developmental anomalies (33 patients, 53.22%) were the most common etiology group followed by traumatic (10 patients, 16.12%), degenerative (eight patients, 12.90%), infective (four patients, 6.45%), inflammatory and neoplastic (three patients each, 4.8%), and no cause found in one patient. Conclusions: CVJ abnormalities constitute an important group of treatable neurological disorders, especially in certain ethnic groups and are approached with much caution by clinicians. Thus, it is essential that radiologists should be able to make a precise diagnosis of craniovertebral junction abnormalities, classify them into etiological group, and rule out important mimickers on MDCT and/or MRI, as this information ultimately helps determine the management of such abnormalities, prognosis, and quality of life of patients. PMID

  7. Functional MR Imaging Techniques in Oncology in the Era of Personalized Medicine.

    PubMed

    Benz, Matthias R; Vargas, Hebert Alberto; Sala, Evis

    2016-02-01

    DW and DCE MR imaging contribute significantly to diagnosis, treatment planning, response assessment, and prognosis in personalized cancer medicine. Nevertheless, the need for further standardization of these techniques needs to be addressed. Whole-body DW MR imaging is an exciting field; however, future studies need to investigate in more depth the biologic significance of the findings depicted, their prognostic relevance, and cost-effectiveness in comparison with MDCT and PET/CT. New MR imaging probes, such as targeted or activatable contrast agents and dynamic nuclear hyperpolarization, show great promise to further improve the care of patients with cancer in the near future.

  8. Functional MRI techniques in oncology in the era of personalized medicine

    PubMed Central

    Benz, Matthias R.; Vargas, Hebert Alberto; Sala, Evis

    2016-01-01

    SYNOPSIS DW and DCE MRI already contribute significantly to several aspects of personalized cancer medicine, namely diagnosis, treatment planning, response assessment, and prognosis. Nevertheless, the need for further standardization of theses imaging techniques is beyond question, and needs to be addressed. Whole body DW MRI is an exciting field, however future studies need to investigate in more depth the biologic significance of the findings depicted, their prognostic relevance and cost effectiveness in comparison to MDCT and PET/CT. New MR imaging probes such as targeted or activatable contrast agents and dynamic nuclear hyperpolarization show great promise to further improve the care of cancer patients in the near future. PMID:26613872

  9. Bias associated with left ventricular quantification by multimodality imaging: a systematic review and meta-analysis

    PubMed Central

    Rigolli, Marzia; Anandabaskaran, Sulakchanan; Christiansen, Jonathan P

    2016-01-01

    Purpose Cardiac MR (CMR) is the gold standard for left ventricular (LV) quantification. However, two-dimensional echocardiography (2DE) is the most common approach, and both three-dimensional echocardiography (3DE) and multidetector CT (MDCT) are increasingly available. The clinical significance and interchangeability of these modalities remains under-investigated. Therefore, we undertook a systemic review to evaluate the accuracy and absolute bias in LV quantification of all the commonly available non-invasive imaging modalities (2DE, CE-2DE, 3DE, MDCT) compared to cardiac MR (CMR). Methods Studies were included that reported LV echocardiographic (2DE, CE-2DE, 3DE) and/or MDCT measurements compared to CMR. Only modern CMR (SSFP sequences) was considered. Studies involving small sample size (<10 patients) and unusual cardiac geometry (ie, congenital heart diseases) were excluded. We evaluated LV end-diastolic volume (LVEDV), end-systolic volume (LVESV) and ejection fraction (LVEF). Results 1604 articles were initially considered: 65 studies were included (total of 4032 scans (echo, CT, MRI) performed in 2888 patients). Compared to CMR, significant biased underestimation of LV volumes with 2DE was seen (LVEDV—33.30 mL, LVESV −16.20 mL, p<0.0001). This difference was reduced but remained significant with CE-2DE (LVEDV −18.05, p<0.0001) and 3DE (LVEDV −14.41, p<0.001), while MDCT values were similar to CMR (LVEDV −1.20, p=0.43; LVESV −0.13, p=0.91). However, excellent agreement for echocardiographic LVEF evaluation (2DE LVEF 0.78–1.01%, p=0.37) was observed, especially with 3DE (LVEF 0.14%, p=0.88). Conclusions Comparing imaging modalities to CMR as reference standard, 3DE had the highest accuracy in LVEF estimation: 2DE and 3DE-derived LV volumes were significantly underestimated. Newer generation CT showed excellent accuracy for LV volumes. PMID:27158524

  10. Improvement in the quality of the cardiac vein images by optimizing the scan protocol of multidetector-row computed tomography.

    PubMed

    Hara, Tetsuya; Yamashiro, Kohei; Okajima, Katsunori; Hayashi, Takatoshi; Kajiya, Teishi

    2009-11-01

    The present study aimed at optimizing the scan protocol for multidetector-row computed tomography (MDCT) to adequately visualize coronary veins. Circulation time (Cir.T) was defined as the time period from the injection of contrast media into the coronary artery to the pervasion of the contrast media into the coronary sinus as observed by coronary angiography. We investigated the relation between the Cir.T and echocardiographic parameters in 64 patients. The left ventricular end-diastolic diameter (LVDd) and left ventricular end-systolic diameter (LVDs) were correlated with the Cir.T (r = 0.58, P < 0.0001, and r = 0.60, P < 0.0001 respectively). In addition, the left ventricular ejection fraction (LVEF) was negatively correlated with the Cir.T (r = 0.48, P < 0.0001). The average Cir. T was longer in patients with LVEF < 35% (8.0 s vs 6.7 s; P < 0.05) or LVDd > 55 mm (7.9 s vs 6.2 s; P < 0.05) than in the other patients. The quality of the MDCT images of the coronary veins obtained at different scan timings (coronary artery phase and 10 s or 15 s after the coronary artery phase) were graded and classified into four categories (0 = worst, 3 = best) in 25 patients with LVEF < 35%. The delays of 10 and 15 s after the coronary artery phase significantly improved the mean image quality (P < 0.05). The Cir.T was prolonged in patients with low LVEF and LV dilation. An appropriate delay improved the quality of the MDCT images of the coronary veins in patients with LV dysfunction.

  11. Heterogeneity of pulmonary perfusion as a mechanistic image-based phenotype in emphysema susceptible smokers

    PubMed Central

    Alford, Sara K.; van Beek, Edwin J. R.; McLennan, Geoffrey; Hoffman, Eric A.

    2010-01-01

    Recent evidence suggests that endothelial dysfunction and pathology of pulmonary vascular responses may serve as a precursor to smoking-associated emphysema. Although it is known that emphysematous destruction leads to vasculature changes, less is known about early regional vascular dysfunction which may contribute to and precede emphysematous changes. We sought to test the hypothesis, via multidetector row CT (MDCT) perfusion imaging, that smokers showing early signs of emphysema susceptibility have a greater heterogeneity in regional perfusion parameters than emphysema-free smokers and persons who had never smoked (NS). Assuming that all smokers have a consistent inflammatory response, increased perfusion heterogeneity in emphysema-susceptible smokers would be consistent with the notion that these subjects may have the inability to block hypoxic vasoconstriction in patchy, small regions of inflammation. Dynamic ECG-gated MDCT perfusion scans with a central bolus injection of contrast were acquired in 17 NS, 12 smokers with normal CT imaging studies (SNI), and 12 smokers with subtle CT findings of centrilobular emphysema (SCE). All subjects had normal spirometry. Quantitative image analysis determined regional perfusion parameters, pulmonary blood flow (PBF), and mean transit time (MTT). Mean and coefficient of variation were calculated, and statistical differences were assessed with one-way ANOVA. MDCT-based MTT and PBF measurements demonstrate globally increased heterogeneity in SCE subjects compared with NS and SNI subjects but demonstrate similarity between NS and SNI subjects. These findings demonstrate a functional lung-imaging measure that provides a more mechanistically oriented phenotype that differentiates smokers with and without evidence of emphysema susceptibility. PMID:20368443

  12. Development and validation of a postmortem radiological alteration index: the RA-Index.

    PubMed

    Egger, C; Vaucher, P; Doenz, F; Palmiere, C; Mangin, P; Grabherr, S

    2012-07-01

    This study aimed to derive an index quantifying the state of alteration of cadavers by quantifying the presence of gas in the body using postmortem multidetector computed tomography (MDCT) imaging, and to validate the index by defining its sensitivity and specificity. The RA (radiological alteration)-index was derived from postmortem MDCT data from 118 nontraumatically deceased people. To validate the index, 100 additional scanned bodies (50 % traumatically deceased) were retrospectively examined by two independent observers. Presence of gas at 82 sites was assessed by a radiologist, whereas a forensic pathologist only investigated the seven sites used for the RA-index. The RA-index was highly correlated to the overall presence of gas in all 82 sites (R(2) = 0.98 in the derivation set and 0.85 in the validation set). Semiquantitative evaluation of gas presence in each site showed moderate reliability (Cohen's kappa range, 0.41-0.78); nevertheless, the overall RA-index was very reliable (ICC(2,1) = 0.95; 95 % CI 0.92-0.96). Examiner using the RA-index detected heart cavities full of gas with a sensitivity of 100 % (95 % CI 51.7-100) and a specificity of 98.8 % (92.6-99.9). We conclude that determining the presence of gas at seven sites is a valid means to measure the distribution of gas due to cadaveric alteration in the entire body. The RA-index is rapid, easy-to-use, and reliable for nonexperienced users, and it is a valid method to suspect the normal presence of gas from cadaveric alteration. MDCT can be used to screen for gas embolism and to give indications for gas composition analysis (gas chromatography).

  13. P2Y2 receptor activation inhibits the expression of the sodium-chloride cotransporter NCC in distal convoluted tubule cells.

    PubMed

    Gailly, P; Szutkowska, M; Olinger, E; Debaix, H; Seghers, F; Janas, S; Vallon, V; Devuyst, O

    2014-11-01

    Luminal nucleotide stimulation is known to reduce Na(+) transport in the distal nephron. Previous studies suggest that this mechanism may involve the thiazide-sensitive Na(+)-Cl(-) cotransporter (NCC), which plays an essential role in NaCl reabsorption in the cells lining the distal convoluted tubule (DCT). Here we show that stimulation of mouse DCT (mDCT) cells with ATP or UTP promoted Ca(2+) transients and decreased the expression of NCC at both mRNA and protein levels. Specific siRNA-mediated silencing of P2Y2 receptors almost completely abolished ATP/UTP-induced Ca(2+) transients and significantly reduced ATP/UTP-induced decrease of NCC expression. To test whether local variations in the intracellular Ca(2+) concentration ([Ca(2+)]i) may control NCC transcription, we overexpressed the Ca(2+)-binding protein parvalbumin selectively in the cytosol or in the nucleus of mDCT cells. The decrease in NCC mRNA upon nucleotide stimulation was abolished in cells overexpressing cytosolic PV but not in cells overexpressing either a nuclear-targeted PV or a mutated PV unable to bind Ca(2+). Using a firefly luciferase reporter gene strategy, we observed that the activity of NCC promoter region from -1 to -2,200 bp was not regulated by changes in [Ca(2+)]i. In contrast, high cytosolic calcium level induced instability of NCC mRNA. We conclude that in mDCT cells: (1) P2Y2 receptor is essential for the intracellular Ca(2+) signaling induced by ATP/UTP stimulation; (2) P2Y2-mediated increase of cytoplasmic Ca(2+) concentration down-regulates the expression of NCC; (3) the decrease of NCC expression occurs, at least in part, via destabilization of its mRNA.

  14. Clinical impact of intraoperative navigation using a Doppler ultrasonographic guided vessel tracking technique for pancreaticoduodenectomy.

    PubMed

    Maemura, Kosei; Mataki, Yuko; Kurahara, Hiroshi; Iino, Satoshi; Sakoda, Masahiko; Ueno, Shinichi; Shinchi, Hiroyuki; Takao, Sonshin; Natsugoe, Shoji

    2014-01-01

    During pancreaticoduodenectomy (PD), early ligation of critical vessels such as the inferior pancreaticoduodenal artery (IPDA) has been reported to reduce blood loss. Color Doppler flow imaging has become the useful diagnostic methods for the delineation of the anatomy. In this study, we assessed the utility of the intraoperative Doppler ultrasonography (Dop-US) guided vessel detection and tracking technique (Dop-Navi) for identifying critical arteries in order to reduce operative bleeding. Ninety patients who received PD for periampullary or pancreatic disease were enrolled. After 14 patients were excluded because of combined resection of portal vein or other organs, the remaining were assigned to 1 of 2 groups: patients for whom Dop-Navi was used (n = 37) and those for whom Dop-Navi was not used (n = 39; controls). We compared the ability of Dop-Navi to identify critical vessels to that of preoperative multi-detector computed tomography (MD-CT), using MD-CT data, as well as compared the perioperative status and postoperative outcome between the 2 patient groups. Intraoperative Dop-US was significantly superior to MD-CT in terms of identifying number of vessels and the ability to discriminate the IPDA from the superior mesenteric artery (SMA) based on blood flow velocity. The Dop-Navi patients had shorter operation times (531 min versus 577 min; no significance) and smaller bleeding volumes (1120 mL versus 1590 mL; P < 0.01) than the control patients without increasing postoperative complications. Intraoperative Dop-Navi method allows surgeons to clearly identify the IPDA during PD and to avoid injuries to major arteries.

  15. Clinical Impact of Intraoperative Navigation Using a Doppler Ultrasonographic Guided Vessel Tracking Technique for Pancreaticoduodenectomy

    PubMed Central

    Maemura, Kosei; Mataki, Yuko; Kurahara, Hiroshi; Iino, Satoshi; Sakoda, Masahiko; Ueno, Shinichi; Shinchi, Hiroyuki; Takao, Sonshin; Natsugoe, Shoji

    2014-01-01

    During pancreaticoduodenectomy (PD), early ligation of critical vessels such as the inferior pancreaticoduodenal artery (IPDA) has been reported to reduce blood loss. Color Doppler flow imaging has become the useful diagnostic methods for the delineation of the anatomy. In this study, we assessed the utility of the intraoperative Doppler ultrasonography (Dop-US) guided vessel detection and tracking technique (Dop-Navi) for identifying critical arteries in order to reduce operative bleeding. Ninety patients who received PD for periampullary or pancreatic disease were enrolled. After 14 patients were excluded because of combined resection of portal vein or other organs, the remaining were assigned to 1 of 2 groups: patients for whom Dop-Navi was used (n = 37) and those for whom Dop-Navi was not used (n = 39; controls). We compared the ability of Dop-Navi to identify critical vessels to that of preoperative multi-detector computed tomography (MD-CT), using MD-CT data, as well as compared the perioperative status and postoperative outcome between the 2 patient groups. Intraoperative Dop-US was significantly superior to MD-CT in terms of identifying number of vessels and the ability to discriminate the IPDA from the superior mesenteric artery (SMA) based on blood flow velocity. The Dop-Navi patients had shorter operation times (531 min versus 577 min; no significance) and smaller bleeding volumes (1120 mL versus 1590 mL; P < 0.01) than the control patients without increasing postoperative complications. Intraoperative Dop-Navi method allows surgeons to clearly identify the IPDA during PD and to avoid injuries to major arteries. PMID:25437586

  16. Magnetic resonance imaging and multi-detector computed tomography assessment of extracellular compartment in ischemic and non-ischemic myocardial pathologies

    PubMed Central

    Saeed, Maythem; Hetts, Steven W; Jablonowski, Robert; Wilson, Mark W

    2014-01-01

    Myocardial pathologies are major causes of morbidity and mortality worldwide. Early detection of loss of cellular integrity and expansion in extracellular volume (ECV) in myocardium is critical to initiate effective treatment. The three compartments in healthy myocardium are: intravascular (approximately 10% of tissue volume), interstitium (approximately 15%) and intracellular (approximately 75%). Myocardial cells, fibroblasts and vascular endothelial/smooth muscle cells represent intracellular compartment and the main proteins in the interstitium are types I/III collagens. Microscopic studies have shown that expansion of ECV is an important feature of diffuse physiologic fibrosis (e.g., aging and obesity) and pathologic fibrosis [heart failure, aortic valve disease, hypertrophic cardiomyopathy, myocarditis, dilated cardiomyopathy, amyloidosis, congenital heart disease, aortic stenosis, restrictive cardiomyopathy (hypereosinophilic and idiopathic types), arrythmogenic right ventricular dysplasia and hypertension]. This review addresses recent advances in measuring of ECV in ischemic and non-ischemic myocardial pathologies. Magnetic resonance imaging (MRI) has the ability to characterize tissue proton relaxation times (T1, T2, and T2*). Proton relaxation times reflect the physical and chemical environments of water protons in myocardium. Delayed contrast enhanced-MRI (DE-MRI) and multi-detector computed tomography (DE-MDCT) demonstrated hyper-enhanced infarct, hypo-enhanced microvascular obstruction zone and moderately enhanced peri-infarct zone, but are limited for visualizing diffuse fibrosis and patchy microinfarct despite the increase in ECV. ECV can be measured on equilibrium contrast enhanced MRI/MDCT and MRI longitudinal relaxation time mapping. Equilibrium contrast enhanced MRI/MDCT and MRI T1 mapping is currently used, but at a lower scale, as an alternative to invasive sub-endomyocardial biopsies to eliminate the need for anesthesia, coronary

  17. Correlations between forced oscillation technique parameters and pulmonary densitovolumetry values in patients with acromegaly

    PubMed Central

    Camilo, G.B.; Carvalho, A.R.S.; Machado, D.C.; Mogami, R.; Kasuki, L.; Gadelha, M.R.; Melo, P.L.; Lopes, A.J.

    2015-01-01

    The aims of this study were to evaluate the forced oscillation technique (FOT) and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT). Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7) vs 11.4 (9.05-17.6) Hz, P=0.023] and a lower value for mean reactance [0.32 (0.21-0.64) vs 0.49 (0.34-0.96) cm H2O/L/s2, P=0.005]. In inspiratory Q-MDCT, the acromegalic patients had higher percentages of total lung volume (TLV) for nonaerated and poorly aerated areas [0.42% (0.30-0.51%) vs 0.25% (0.20-0.32%), P=0.039 and 3.25% (2.48-3.46%) vs 1.70% (1.45-2.15%), P=0.001, respectively]. Furthermore, the acromegalic patients had higher values for total lung mass in both inspiratory and expiratory Q-MDCT [821 (635-923) vs 696 (599-769) g, P=0.021 and 844 (650-945) vs 637 (536-736) g, P=0.009, respectively]. In inspiratory Q-MDCT, TLV showed significant correlations with all FOT parameters. The TLV of hyperaerated areas showed significant correlations with intercept resistance (rs=−0.602, P<0.001) and mean resistance (rs=−0.580, P<0.001). These data showed that acromegalic patients have increased amounts of lung tissue as well as nonaerated and poorly aerated areas. Functionally, there was a loss of homogeneity of the respiratory system. Moreover, there were correlations between the structural and functional findings of the respiratory system, consistent with the pathophysiology of the disease. PMID:26445330

  18. Genome-wide analysis of murine renal distal convoluted tubular cells for the target genes of mineralocorticoid receptor

    SciTech Connect

    Ueda, Kohei; Fujiki, Katsunori; Shirahige, Katsuhiko; Gomez-Sanchez, Celso E.; Fujita, Toshiro; Nangaku, Masaomi; Nagase, Miki

    2014-02-28

    Highlights: • We define a target gene of MR as that with MR-binding to the adjacent region of DNA. • We use ChIP-seq analysis in combination with microarray. • We, for the first time, explore the genome-wide binding profile of MR. • We reveal 5 genes as the direct target genes of MR in the renal epithelial cell-line. - Abstract: Background and objective: Mineralocorticoid receptor (MR) is a member of nuclear receptor family proteins and contributes to fluid homeostasis in the kidney. Although aldosterone-MR pathway induces several gene expressions in the kidney, it is often unclear whether the gene expressions are accompanied by direct regulations of MR through its binding to the regulatory region of each gene. The purpose of this study is to identify the direct target genes of MR in a murine distal convoluted tubular epithelial cell-line (mDCT). Methods: We analyzed the DNA samples of mDCT cells overexpressing 3xFLAG-hMR after treatment with 10{sup −7} M aldosterone for 1 h by chromatin immunoprecipitation with deep-sequence (ChIP-seq) and mRNA of the cell-line with treatment of 10{sup −7} M aldosterone for 3 h by microarray. Results: 3xFLAG-hMR overexpressed in mDCT cells accumulated in the nucleus in response to 10{sup −9} M aldosterone. Twenty-five genes were indicated as the candidate target genes of MR by ChIP-seq and microarray analyses. Five genes, Sgk1, Fkbp5, Rasl12, Tns1 and Tsc22d3 (Gilz), were validated as the direct target genes of MR by quantitative RT-qPCR and ChIP-qPCR. MR binding regions adjacent to Ctgf and Serpine1 were also validated. Conclusions: We, for the first time, captured the genome-wide distribution of MR in mDCT cells and, furthermore, identified five MR target genes in the cell-line. These results will contribute to further studies on the mechanisms of kidney diseases.

  19. Correlations between forced oscillation technique parameters and pulmonary densitovolumetry values in patients with acromegaly.

    PubMed

    Camilo, G B; Carvalho, A R S; Machado, D C; Mogami, R; Kasuki, L; Gadelha, M R; Melo, P L; Lopes, A J

    2015-10-01

    The aims of this study were to evaluate the forced oscillation technique (FOT) and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT). Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7) vs 11.4 (9.05-17.6) Hz, P=0.023] and a lower value for mean reactance [0.32 (0.21-0.64) vs 0.49 (0.34-0.96) cm H2O/L/s2, P=0.005]. In inspiratory Q-MDCT, the acromegalic patients had higher percentages of total lung volume (TLV) for nonaerated and poorly aerated areas [0.42% (0.30-0.51%) vs 0.25% (0.20-0.32%), P=0.039 and 3.25% (2.48-3.46%) vs 1.70% (1.45-2.15%), P=0.001, respectively]. Furthermore, the acromegalic patients had higher values for total lung mass in both inspiratory and expiratory Q-MDCT [821 (635-923) vs 696 (599-769) g, P=0.021 and 844 (650-945) vs 637 (536-736) g, P=0.009, respectively]. In inspiratory Q-MDCT, TLV showed significant correlations with all FOT parameters. The TLV of hyperaerated areas showed significant correlations with intercept resistance (rs=-0.602, P<0.001) and mean resistance (rs=-0.580, P<0.001). These data showed that acromegalic patients have increased amounts of lung tissue as well as nonaerated and poorly aerated areas. Functionally, there was a loss of homogeneity of the respiratory system. Moreover, there were correlations between the structural and functional findings of the respiratory system, consistent with the pathophysiology of the disease.

  20. Correlations between forced oscillation technique parameters and pulmonary densitovolumetry values in patients with acromegaly.

    PubMed

    Camilo, G B; Carvalho, A R S; Machado, D C; Mogami, R; Kasuki, L; Gadelha, M R; Melo, P L; Lopes, A J

    2015-08-04

    The aims of this study were to evaluate the forced oscillation technique (FOT) and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT). Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7) vs 11.4 (9.05-17.6) Hz, P=0.023] and a lower value for mean reactance [0.32 (0.21-0.64) vs 0.49 (0.34-0.96) cm H2O/L/s2, P=0.005]. In inspiratory Q-MDCT, the acromegalic patients had higher percentages of total lung volume (TLV) for nonaerated and poorly aerated areas [0.42% (0.30-0.51%) vs 0.25% (0.20-0.32%), P=0.039 and 3.25% (2.48-3.46%) vs 1.70% (1.45-2.15%), P=0.001, respectively]. Furthermore, the acromegalic patients had higher values for total lung mass in both inspiratory and expiratory Q-MDCT [821 (635-923) vs 696 (599-769) g, P=0.021 and 844 (650-945) vs 637 (536-736) g, P=0.009, respectively]. In inspiratory Q-MDCT, TLV showed significant correlations with all FOT parameters. The TLV of hyperaerated areas showed significant correlations with intercept resistance (rs=-0.602, P<0.001) and mean resistance (rs=-0.580, P<0.001). These data showed that acromegalic patients have increased amounts of lung tissue as well as nonaerated and poorly aerated areas. Functionally, there was a loss of homogeneity of the respiratory system. Moreover, there were correlations between the structural and functional findings of the respiratory system, consistent with the pathophysiology of the disease.

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  1. Fostering Effective Studying and Study Planning with Study Questions

    ERIC Educational Resources Information Center

    Wilhelm, Pascal; Pieters, Jules M.

    2007-01-01

    In a course on biological psychology and neuropsychology, study questions were provided that also appeared as test questions in the course exam. This method was introduced to support students in active processing and reproduction of the study texts, and study planning. Data were gathered to test the hypothesis that study question use would be…

  2. Case Study: Testing with Case Studies

    ERIC Educational Resources Information Center

    Herreid, Clyde Freeman

    2015-01-01

    This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. This month's issue discusses using case studies to test for knowledge or lessons learned.

  3. The role of mobile computed tomography in mass fatality incidents.

    PubMed

    Rutty, Guy N; Robinson, Claire E; BouHaidar, Ralph; Jeffery, Amanda J; Morgan, Bruno

    2007-11-01

    Mobile multi-detector computed tomography (MDCT) scanners are potentially available to temporary mortuaries and can be operational within 20 min of arrival. We describe, to our knowledge, the first use of mobile MDCT for a mass fatality incident. A mobile MDCT scanner attended the disaster mortuary after a five vehicle road traffic incident. Five out of six bodies were successfully imaged by MDCT in c. 15 min per body. Subsequent full radiological analysis took c. 1 h per case. The results were compared to the autopsy examinations. We discuss the advantages and disadvantages of imaging with mobile MDCT in relation to mass fatality work, illustrating the body pathway process, and its role in the identification of the pathology, personal effects, and health and safety hazards. We propose that the adoption of a single modality of mobile MDCT could replace the current use of multiple radiological sources within a mass fatality mortuary.

  4. AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiologic study of a large cohort of pesticide applicators and their spouses in Iowa and North Carolina. The Pesticide Exposure Study is a sub-study to evaluate exposure factors and to provide data to assess exposure cla...

  5. SU-F-207-16: CT Protocols Optimization Using Model Observer

    SciTech Connect

    Tseng, H; Fan, J; Kupinski, M

    2015-06-15

    Purpose: To quantitatively evaluate the performance of different CT protocols using task-based measures of image quality. This work studies the task of size and the contrast estimation of different iodine concentration rods inserted in head- and body-sized phantoms using different imaging protocols. These protocols are designed to have the same dose level (CTDIvol) but using different X-ray tube voltage settings (kVp). Methods: Different concentrations of iodine objects inserted in a head size phantom and a body size phantom are imaged on a 64-slice commercial CT scanner. Scanning protocols with various tube voltages (80, 100, and 120 kVp) and current settings are selected, which output the same absorbed dose level (CTDIvol). Because the phantom design (size of the iodine objects, the air gap between the inserted objects and the phantom) is not ideal for a model observer study, the acquired CT images are used to generate simulation images with four different sizes and five different contracts iodine objects. For each type of the objects, 500 images (100 x 100 pixels) are generated for the observer study. The observer selected in this study is the channelized scanning linear observer which could be applied to estimate the size and the contrast. The figure of merit used is the correct estimation ratio. The mean and the variance are estimated by the shuffle method. Results: The results indicate that the protocols with 100 kVp tube voltage setting provides the best performance for iodine insert size and contrast estimation for both head and body phantom cases. Conclusion: This work presents a practical and robust quantitative approach using channelized scanning linear observer to study contrast and size estimation performance from different CT protocols. Different protocols at same CTDIvol setting could Result in different image quality performance. The relationship between the absorbed dose and the diagnostic image quality is not linear.

  6. Multidetector computed tomography of pediatric large airway diseases: state-of-the-art.

    PubMed

    Lee, Edward Y; Greenberg, S Bruce; Boiselle, Phillip M

    2011-09-01

    Advances in multidetector computed tomography (MDCT) technology have given rise to improvements in the noninvasive and comprehensive assessment of the large airways in pediatric patients. Superb two-dimensional and three-dimensional reconstruction MDCT images have revolutionized the display of large airways and enhanced the ability to diagnose large airway diseases in children. The 320-MDCT scanner, which provides combined detailed anatomic and dynamic functional information assessment of the large airways, is promising for the assessment of dynamic large airway disease such as tracheobronchomalacia. This article discusses imaging techniques and clinical applications of MDCT for assessing large airway diseases in pediatric patients.

  7. CASE STUDY CRITIQUE; UPPER CLINCH CASE STUDY

    EPA Science Inventory

    Case study critique: Upper Clinch case study (from Research on Methods for Integrating Ecological Economics and Ecological Risk Assessment: A Trade-off Weighted Index Approach to Integrating Economics and Ecological Risk Assessment). This critique answers the questions: 1) does ...

  8. Case Study: Writing a Journal Case Study

    ERIC Educational Resources Information Center

    Prud'homme-Genereux, Annie

    2016-01-01

    This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. This month's issue describes incorporating a journal article into the classroom by first converting it into a case study.

  9. Ecological baseline studies

    NASA Technical Reports Server (NTRS)

    Vickers, D.

    1980-01-01

    Environmental studies of Merritt Island are discussed. Five areas of the island's ecology are examined. They include: a terrestrial community analyses, a plant community study, a small mammal population study, a rainfall study, and an ichthyological analyses.

  10. Treatment of patients with aortic atherosclerotic disease with paclitaxel-associated lipid nanoparticles

    PubMed Central

    Shiozaki, Afonso A.; Senra, Tiago; Morikawa, Aleksandra T.; Deus, Débora F.; Paladino, Antonio T; Pinto, Ibraim M.F.; Maranhão, Raul C.

    2016-01-01

    OBJECTIVE: The toxicity of anti-cancer chemotherapeutic agents can be reduced by associating these compounds, such as the anti-proliferative agent paclitaxel, with a cholesterol-rich nanoemulsion (LDE) that mimics the lipid composition of low-density lipoprotein (LDL). When injected into circulation, the LDE concentrates the carried drugs in neoplastic tissues and atherosclerotic lesions. In rabbits, atherosclerotic lesion size was reduced by 65% following LDE-paclitaxel treatment. The current study aimed to test the effectiveness of LDE-paclitaxel on inpatients with aortic atherosclerosis. METHODS: This study tested a 175 mg/m2 body surface area dose of LDE-paclitaxel (intravenous administration, 3/3 weeks for 6 cycles) in patients with aortic atherosclerosis who were aged between 69 and 86 yrs. A control group of 9 untreated patients with aortic atherosclerosis (72-83 yrs) was also observed. RESULTS: The LDE-paclitaxel treatment elicited no important clinical or laboratory toxicities. Images were acquired via multiple detector computer tomography angiography (64-slice scanner) before treatment and at 1-2 months after treatment. The images showed that the mean plaque volume in the aortic artery wall was reduced in 4 of the 8 patients, while in 3 patients it remained unchanged and in one patient it increased. In the control group, images were acquired twice with an interval of 6-8 months. None of the patients in this group exhibited a reduction in plaque volume; in contrast, the plaque volume increased in three patients and remained stable in four patients. During the study period, one death unrelated to the treatment occurred in the LDE-paclitaxel group and one death occurred in the control group. CONCLUSION: Treatment with LDE-paclitaxel was tolerated by patients with cardiovascular disease and showed the potential to reduce atherosclerotic lesion size. PMID:27626473

  11. Intrinsic Cardiac Autonomic Ganglionated Plexi within Epicardial Fats Modulate the Atrial Substrate Remodeling: Experiences with Atrial Fibrillation Patients Receiving Catheter Ablation

    PubMed Central

    Singhal, Rahul; Lo, Li-Wei; Lin, Yenn-Jiang Lin; Chang, Shih-Lin; Hu, Yu-Feng; Chao, Tze-Fan; Chung, Fa-Po; Chiou, Cheun-Wang; Tsao, Hsuan-Ming; Chen, Shih-Ann

    2016-01-01

    Background A recent study reported the close relationship between high dominant frequent (DF) sites [atrial fibrillation (AF) nest] and the intrinsic cardiac autonomic nervous system. The aim of this study was to investigate the correlation between the regional distribution of epicardial fat and the properties of the biatrial substrates in AF patients. Methods We studied 32 patients with paroxysmal (n = 23) and persistent (n = 9) AF. The epicardial fat volume around the left atrium (LA) was evaluated using 64-slice multidetector computed tomography and the topographic distribution of the fat volume was assessed. The biatrial DFs, voltages, and total activation times (TATs) were obtained during sinus rhythm. Results Out of the 8 divided LA regions, a significant linear correlation existed between the LA fat and mean DF values in the right upper anterior LA, left upper anterior LA, right lower anterior LA, right upper posterior LA, left upper posterior LA, and left lower posterior LA. There was no significant correlation between the regional LA fat distribution and regional LA peak-to-peak bipolar voltage and TAT. During a mean follow-up of 17 ± 8 months, 22 of the 32 (69%) patients were free of AF. In the multivariate analysis, only the mean LA DF was found to be a significant predictor of recurrence. Conclusions There was a close association between the regional distribution of the LA epicardial fat and the atrial substrate manifesting high frequency during sinus rhythm (AF nest). Those nests were related to ablation outcome. Hence, epicardial fat may play a significant role in atrial substrate remodeling and thereby in the pathogenesis and maintenance of AF. PMID:27122948

  12. SU-E-I-57: Evaluation and Optimization of Effective-Dose Using Different Beam-Hardening Filters in Clinical Pediatric Shunt CT Protocol

    SciTech Connect

    Gill, K; Aldoohan, S; Collier, J

    2014-06-01

    Purpose: Study image optimization and radiation dose reduction in pediatric shunt CT scanning protocol through the use of different beam-hardening filters Methods: A 64-slice CT scanner at OU Childrens Hospital has been used to evaluate CT image contrast-to-noise ratio (CNR) and measure effective-doses based on the concept of CT dose index (CTDIvol) using the pediatric head shunt scanning protocol. The routine axial pediatric head shunt scanning protocol that has been optimized for the intrinsic x-ray tube filter has been used to evaluate CNR by acquiring images using the ACR approved CT-phantom and radiation dose CTphantom, which was used to measure CTDIvol. These results were set as reference points to study and evaluate the effects of adding different filtering materials (i.e. Tungsten, Tantalum, Titanium, Nickel and Copper filters) to the existing filter on image quality and radiation dose. To ensure optimal image quality, the scanner routine air calibration was run for each added filter. The image CNR was evaluated for different kVps and wide range of mAs values using above mentioned beam-hardening filters. These scanning protocols were run under axial as well as under helical techniques. The CTDIvol and the effective-dose were measured and calculated for all scanning protocols and added filtration, including the intrinsic x-ray tube filter. Results: Beam-hardening filter shapes energy spectrum, which reduces the dose by 27%. No noticeable changes in image low contrast detectability Conclusion: Effective-dose is very much dependent on the CTDIVol, which is further very much dependent on beam-hardening filters. Substantial reduction in effective-dose is realized using beam-hardening filters as compare to the intrinsic filter. This phantom study showed that significant radiation dose reduction could be achieved in CT pediatric shunt scanning protocols without compromising in diagnostic value of image quality.

  13. Whole-body biodistribution of 3'-deoxy-3'-[(18) f]fluorothymidine ((18) FLT) in healthy adult cats.

    PubMed

    Rowe, Joshua A; Morandi, Federica; Wall, Jonathan S; Akula, Murthy; Kennel, Stephen J; Osborne, Dustin; Martin, Emily B; Galyon, Gina D; Long, Misty J; Stuckey, Alan C; LeBlanc, Amy K

    2013-01-01

    Positron emission tomography/computed tomography (PET/CT) utilizing 3'-deoxy-3'-[(18) F]fluorothymidine ((18) FLT), a proliferation tracer, has been found to be a useful tool for characterizing neoplastic diseases and bone marrow function in humans. As PET and PET/CT imaging become increasingly available in veterinary medicine, knowledge of radiopharmaceutical biodistribution in veterinary species is needed for lesion interpretation in the clinical setting. The purpose of this study was to describe the normal biodistribution of (18) FLT in adult domestic cats. Imaging of six healthy young adult castrated male cats was performed using a commercially available PET/CT scanner consisting of a 64-slice helical CT scanner with an integrated whole-body, high-resolution lutetium oxy-orthosilicate (LSO) PET scanner. Cats were sedated and injected intravenously with 108.60 ± 2.09 (mean ± SD) MBq of (18) FLT (greater than 99% radiochemical purity by high-performance liquid chromatography). Imaging was performed in sternal recumbency under general anesthesia. Static images utilizing multiple bed positions were acquired 80.83 ± 7.52 (mean ± SD) minutes post-injection. Regions of interest were manually drawn over major parenchymal organs and selected areas of bone marrow and increased tracer uptake. Standardized uptake values were calculated. Notable areas of uptake included hematopoietic bone marrow, intestinal tract, and the urinary and hepatobiliary systems. No appreciable uptake was observed within brain, lung, myocardium, spleen, or skeletal muscle. Findings from this study can be used as baseline data for future studies of diseases in cats.

  14. Gallbladder metastasis: spectrum of imaging findings.

    PubMed

    Barretta, Maria Luisa; Catalano, Orlando; Setola, Sergio Venanzio; Granata, Vincenza; Marone, Ugo; D'Errico Gallipoli, Adolfo

    2011-12-01

    The objective of this study is to report the diagnostic features of hematogenous gallbladder metastasis using various imaging modalities. We carried out a single-center retrospective analysis of 13 patients with gallbladder metastasis. The primary malignancy was cutaneous melanoma (11 cases), hepatocellular carcinoma (1 case), and non-Hodgkin lymphoma (1 case). All patients underwent sonography (US), with color-power-Doppler assessment in 11 cases. Contrast-enhanced US (CEUS) was performed in 8 patients, MDCT in 8, and MR imaging in 1. Four subjects studied by whole-body PET. The gallbladder lesions were first detected with US in 9 cases and with MDCT in 3 cases. The remaining patient was investigated because of hepatic fluorodeoxyglucose uptake at PET; CEUS failed to detect any liver metastasis in this subject but identified a gallbladder lesion. Typical findings included multiplicity of gallbladder vegetations, broad base, limited mural thickening, presence of contrast enhancement, absence of gallstones and gallbladder bed infiltration, presence of combined lesions within other organs. Only two patients presented an isolated location in the gallbladder and were successfully treated with surgery. Gallbladder metastasis is a rare but possible occurrence. Knowledge of the typical imaging features and careful evaluation of the gallbladder may avoid an incorrect or false negative diagnosis.

  15. Multidetector CT Findings of Bowel Transection in Blunt Abdominal Trauma

    PubMed Central

    Cho, Hyun Suk; Hong, Hye-Suk; Park, Mee Hyun; Ha, Hong Il; Yang, Ik; Lee, Yul; Jung, Ah Young; Hwang, Ji-Young

    2013-01-01

    Objective Though a number of CT findings of bowel and mesenteric injuries in blunt abdominal trauma are described in literature, no studies on the specific CT signs of a transected bowel have been published. In the present study we describe the incidence and new CT signs of bowel transection in blunt abdominal trauma. Materials and Methods We investigated the incidence of bowel transection in 513 patients admitted for blunt abdominal trauma who underwent multidetector CT (MDCT). The MDCT findings of 8 patients with a surgically proven complete bowel transection were assessed retrospectively. We report novel CT signs that are unique for transection, such as complete cutoff sign (transection of bowel loop), Janus sign (abnormal dual bowel wall enhancement, both increased and decreased), and fecal spillage. Results The incidence of bowel transection in blunt abdominal trauma was 1.56%. In eight cases of bowel transection, percentage of CT signs unique for bowel transection were as follows: complete cutoff in 8 (100%), Janus sign in 6 (100%, excluding duodenal injury), and fecal spillage in 2 (25%). The combination of complete cutoff and Janus sign were highly specific findings in patients with bowel transection. Conclusion Complete cut off and Janus sign are the unique CT findings to help detect bowel transection in blunt abdominal trauma and recognition of these findings enables an accurate and prompt diagnosis for emergency laparotomy leading to reduced mortality and morbidity. PMID:23901318

  16. Evaluation of bone substitute materials: comparison of flat-panel based volume CT to conventional multidetector CT.

    PubMed

    Sauerbier, Sebastian; Duttenhoefer, Fabian; Sachlos, Elefterios; Haberstroh, Jörg; Scheifele, Christian; Wrbas, Karl-Thomas; Voss, Pit Jacob; Veigel, Egle; Smedek, Jörg; Ganter, Philip; Tuna, Taskin; Gutwald, Ralf; Palmowski, Moritz

    2013-10-01

    Over the last decade tissue engineering has emerged as a key factor in bone regeneration within the field of cranio-maxillofacial surgery. Despite this in vivo analysis of tissue-engineered-constructs to monitor bone rehabilitation are difficult to conduct. Novel high-resolving flat-panel based volume CTs (fp-VCT) are increasingly used for imaging bone structures. This study compares the potential value of novel fp-VCT with conventional multidetector CT (MDCT) based on a sheep sinus floor elevation model. Calcium-hydroxyapatite reinforced collagen scaffolds were populated with autologous osteoblasts and implanted into sheep maxillary sinus. After 8, 16 and 24 weeks MDCT and fp-VCT scans were performed to investigate the volume of the augmented area; densities of cancellous and compact bone were assessed as comparative values. fp-VCT imaging resulted in higher spatial resolution, which was advantageous when separating closely related anatomical structures (i.e. trabecular and compact bone, biomaterials). Fp-VCT facilitated imaging of alterations occurring in test specimens over time. fp-VCTs therefore displayed high volume coverage, dynamic imaging potential and superior performance when investigating superfine bone structures and bone remodelling of biomaterials. Thus, fp-VCTs may be a suitable instrument for intraoperative imaging and future in vivo tissue-engineering studies.

  17. ASSESSMENT OF EFFECTIVE DOSE FROM CONE BEAM CT IMAGING IN SPECT/CT EXAMINATION IN COMPARISON WITH OTHER MODALITIES.

    PubMed

    Tonkopi, Elena; Ross, Andrew A

    2016-12-01

    The aim of this study was to assess radiation dose from the cone beam computed tomography (CBCT) component of single photon emission tomography/computed tomography (SPECT/CT) examinations and to compare it with the radiopharmaceutical related dose as well as dose from multidetector computed tomography (MDCT). Effective dose (ED) from computed tomography (CT) was estimated using dose-length product values and anatomy-specific conversion factors. The contribution from the SPECT component was evaluated using ED per unit administered activity for the radiopharmaceuticals listed in the International Commission on Radiological Protection Publications 80 and 106. With the exception of cardiac studies (0.11 mSv), the CBCT dose (3.96-6.04 mSv) was similar to that from the radiopharmaceutical accounting for 29-56 % of the total ED from the examination. In comparison with MDCT examinations, the CBCT dose was 48 and 42 % lower for abdomen/pelvis and chest/abdomen/pelvis scans, respectively, while in the chest the CBCT scan resulted in higher dose (23 %). Radiation dose from the CT component should be taken into consideration when evaluating total SPECT/CT patient dose.

  18. CT-automatic exposure control devices: What are their performances?

    NASA Astrophysics Data System (ADS)

    Gutierrez, Daniel; Schmidt, Sabine; Denys, Alban; Schnyder, Pierre; Bochud, François O.; Verdun, Francis R.

    2007-10-01

    PurposeTo avoid unnecessary exposure to the patients, constructors have developed tube current modulation algorithms. The purpose of this work is to assess the performance of computed tomography (CT) tube current modulation concerning patient dose and image noise in MSCT scanners. Material and methodsA conical PMMA phantom with elliptical cross-section, to vary the thickness of the irradiated object in a monotonous way, and an anthropomorphic chest phantom were scanned under similar conditions on a general electrics (GE) LightSpeed VCT (64 slices) scanner. Noise measurements were made by calculating the standard deviation of the CT-number on a homogeneous ROI in both phantoms. The dose was estimated with the parameters read in the DICOM header of each studied image. ResultsThe study has shown that most of the time, constant noise levels (noise index) can be obtained by a variation of the mA. Nevertheless, this adaptation can be not fast enough when the variation of the attenuation changes is rapid. Thus, an adaptation length up to 5 cm was obtained. A 18% dose reduction can be achieved (mean of 9.9%) by switching from z-axis modulation algorithm to xyz-axis modulation option. However, exposure in the chest area can be higher with current modulation than without, when trying to keep an image noise level constant in thoraco-abdominal investigations. ConclusionCurrent modulation algorithms can produce inadequate quality images due to problems with tube current stabilization when a sudden attenuation variation takes place as at the start of a scanning sequence. As expected, rotational ( xyz-axis) modulation performs better than only z-axis modulation algorithm. The use of automatic exposure control (AEC) can lead to an increase of the dose if the maximum allowed current is not properly set in thoraco-abdominal acquisitions.

  19. Patient radiation biological risk in computed tomography angiography procedure.

    PubMed

    Alkhorayef, M; Babikir, E; Alrushoud, A; Al-Mohammed, H; Sulieman, A

    2017-02-01

    Computed tomography angiography (CTA) has become the most valuable imaging modality for the diagnosis of blood vessel diseases; however, patients are exposed to high radiation doses and the probability of cancer and other biological effects is increased. The objectives of this study were to measure the patient radiation dose during a CTA procedure and to estimate the radiation dose and biological effects. The study was conducted in two radiology departments equipped with 64-slice CT machines (Aquilion) calibrated according to international protocols. A total of 152 patients underwent brain, lower limb, chest, abdomen, and pelvis examinations. The effective radiation dose was estimated using ImPACT scan software. Cancer and biological risks were estimated using the International Commission on Radiological Protection (ICRP) conversion factors. The mean patient dose value per procedure (dose length product [DLP], mGy·cm) for all examinations was 437.8 ± 166, 568.8 ± 194, 516.0 ± 228, 581.8 ± 175, and 1082.9 ± 290 for the lower limbs, pelvis, abdomen, chest, and cerebral, respectively. The lens of the eye, uterus, and ovaries received high radiation doses compared to thyroid and testis. The overall patient risk per CTA procedure ranged between 15 and 36 cancer risks per 1 million procedures. Patient risk from CTA procedures is high during neck and abdomen procedures. Special concern should be provided to the lens of the eye and thyroid during brain CTA procedures. Patient dose reduction is an important consideration; thus, staff should optimize the radiation dose during CTA procedures.

  20. Incidental pulmonary embolism in cancer patients: clinical characteristics and outcome – a comprehensive cancer center experience

    PubMed Central

    Abdel-Razeq, Hikmat N; Mansour, Asem H; Ismael, Yousef M

    2011-01-01

    Background and objectives: Cancer patients undergo routine imaging studies much more than others. The widespread use of the recently introduced multi-detector CT scanners has resulted in an increasing number of incidentally diagnosed pulmonary embolism (PE) in asymptomatic cancer patients. The significance and clinical outcome of such incidental PE is described. Methods: Both radiology department and hospital databases were searched for all cancer patients with a diagnosis of incidental PE. CT scans were performed using a 64-slice scanner with a 5.0 mm slice thickness. Results: During the study period, 34 patients with incidental PE were identified. The mean age (±SD) was 57.7 (±12.4) years. All patients had active cancer, gastric, lung, colorectal, and lymphomas being the most frequent. Most patients had advanced-stage disease at the time of PE diagnosis; 26 (77%) patients had stage IV, whereas only 3 patients had stages I or II disease. Twenty-seven (79%) patients had their PE while undergoing active treatment with chemotherapy (68%) or radiotherapy (12%); none, however, were on hormonal therapy. Most (74%) patients had their PE diagnosed without history of recent hospital admission. Except for 5 (15%), all other patients were anticoagulated. With follow-up, 2 patients developed recurrent PE, 2 others had clinical and echocardiographic evidence of pulmonary hypertension, and 9 (26%) died suddenly within 30 days of the diagnosis of incidental PE; 2 of these where among the 5 patients who were not anticoagulated. Conclusion: Incidental PE in cancer patients is increasingly encountered. Similar to symptomatic PE, many were diagnosed in patients with advanced stage disease and while undergoing active anti-cancer therapy. A significant percentage of patients had recurrent emboli, pulmonary hypertension, and sudden death. PMID:21468175

  1. German Studies in America. German Studies Notes.

    ERIC Educational Resources Information Center

    Sander, Volkmar; Osterle, Heinz D.

    This volume contains two papers, "German Studies in America," by Volkmar Sander, and "Historicism, Marxism, Structuralism: Ideas for German Culture Courses," by Heinz D. Osterle. The first paper discusses the position of German studies in the United States today. The greatest challenge comes from low enrollments; therefore,…

  2. Ethnographic Study: @ONE Technology Training Project Study.

    ERIC Educational Resources Information Center

    Obler, Susan; Schiorring, Eva

    This report presents findings from an ethnographic study of technology integration and diffusion in two California community colleges. The study was commissioned to examine whether faculty behavior and student learning outcomes have changed as a result of @ONE instructional technology training and resources. The California Community Colleges…

  3. Assessment of low-flow, low-gradient aortic stenosis: multimodality imaging is the key to success.

    PubMed

    Clavel, Marie-Annick; Pibarot, Philippe

    2014-09-01

    In patients with aortic stenosis (AS), a low-flow state may occur with reduced LV ejection fraction (LVEF) (i.e., classic low flow) or with preserved LVEF (i.e., paradoxical low flow) and it is often associated with low gradient because the gradient is highly flow-dependent. Low-flow, low-gradient (LF-LG) AS is a frequent clinical entity generally associated with worse outcomes. A multimodality imaging approach, including comprehensive resting echocardiography, dobutamine stress echocardiography (DSE), and multidetector computed tomography (MDCT), is the key to successful management of patients with LF-LG AS, who represent a highly challenging subset from both a diagnostic and a therapeutic standpoint. DSE and quantification of aortic valve calcification by MDCT provide important information that is crucial to differentiate true-severe from pseudo-severe AS and therefore select the most appropriate therapy (i.e., AVR vs. medical). The assessment of LV flow reserve by DSE is useful to stratify the operative risk and guide decision making between surgical and transcatheter AVR. Other imaging biomarkers, such as the global LV longitudinal strain measured during DSE or the amount of myocardial fibrosis assessed by cardiac magnetic resonance imaging, may provide incremental information for risk stratification and therapeutic management in LF-LG AS, but additional studies are needed to validate and refine these emerging biomarkers further.

  4. Assessing vertebral fracture risk on volumetric quantitative computed tomography by geometric characterization of trabecular bone structure

    NASA Astrophysics Data System (ADS)

    Checefsky, Walter A.; Abidin, Anas Z.; Nagarajan, Mahesh B.; Bauer, Jan S.; Baum, Thomas; Wismüller, Axel

    2016-03-01

    The current clinical standard for measuring Bone Mineral Density (BMD) is dual X-ray absorptiometry, however more recently BMD derived from volumetric quantitative computed tomography has been shown to demonstrate a high association with spinal fracture susceptibility. In this study, we propose a method of fracture risk assessment using structural properties of trabecular bone in spinal vertebrae. Experimental data was acquired via axial multi-detector CT (MDCT) from 12 spinal vertebrae specimens using a whole-body 256-row CT scanner with a dedicated calibration phantom. Common image processing methods were used to annotate the trabecular compartment in the vertebral slices creating a circular region of interest (ROI) that excluded cortical bone for each slice. The pixels inside the ROI were converted to values indicative of BMD. High dimensional geometrical features were derived using the scaling index method (SIM) at different radii and scaling factors (SF). The mean BMD values within the ROI were then extracted and used in conjunction with a support vector machine to predict the failure load of the specimens. Prediction performance was measured using the root-mean-square error (RMSE) metric and determined that SIM combined with mean BMD features (RMSE = 0.82 +/- 0.37) outperformed MDCT-measured mean BMD (RMSE = 1.11 +/- 0.33) (p < 10-4). These results demonstrate that biomechanical strength prediction in vertebrae can be significantly improved through the use of SIM-derived texture features from trabecular bone.

  5. Comparison of Intraoperative Portable CT Scanners in Skull Base and Endoscopic Sinus Surgery: Single Center Case Series

    PubMed Central

    Conley, David B.; Tan, Bruce; Bendok, Bernard R.; Batjer, H. Hunt; Chandra, Rakesh; Sidle, Douglas; Rahme, Rudy J.; Adel, Joseph G.; Fishman, Andrew J.

    2011-01-01

    Precise and safe management of complex skull base lesions can be enhanced by intraoperative computed tomography (CT) scanning. Surgery in these areas requires real-time feedback of anatomic landmarks. Several portable CT scanners are currently available. We present a comparison of our clinical experience with three portable scanners in skull base and craniofacial surgery. We present clinical case series and the participants were from the Northwestern Memorial Hospital. Three scanners are studied: one conventional multidetector CT (MDCT), two digital flat panel cone-beam CT (CBCT) devices. Technical considerations, ease of use, image characteristics, and integration with image guidance are presented for each device. All three scanners provide good quality images. Intraoperative scanning can be used to update the image guidance system in real time. The conventional MDCT is unique in its ability to resolve soft tissue. The flat panel CBCT scanners generally emit lower levels of radiation and have less metal artifact effect. In this series, intraoperative CT scanning was technically feasible and deemed useful in surgical decision-making in 75% of patients. Intraoperative portable CT scanning has significant utility in complex skull base surgery. This technology informs the surgeon of the precise extent of dissection and updates intraoperative stereotactic navigation. PMID:22470270

  6. Percutaneous Treatment of Sac Rupture in Abdominal Aortic Aneurysms Previously Excluded with Endovascular Repair (EVAR)

    SciTech Connect

    Lagana, Domenico Mangini, Monica Fontana, Federico; Nicotera, Paolo; Carrafiello, Gianpaolo; Fugazzola, Carlo

    2009-01-15

    The purpose of this study was to assess the feasibility and effectiveness of percutaneous endovascular repair of ruptured abdominal aortic aneurysms (AAAs) previously treated by EVAR. In the last year, two male patients with AAAs, treated 8 and 23 months ago with bifurcated stent-graft, were observed because of lumbar pain and hemorragic shock. Multidetector computed tomography (MDCT) showed a retroperitoneal hematoma; in both cases a type III endoleak was detected, in one case associated with a type II endoleak from the iliolumbar artery. The procedures were performed in the theater, in emergency. Type II endoleak was treated with transcatheter superselective glue injection; type III endoleaks were excluded by a stent-graft extension. The procedures were successful in both patients, with immediate hemodynamic stabilization. MDCT after the procedure showed complete exclusion of the aneurysms. In conclusion, endovascular treatment is a safe and feasible option for the treatment of ruptured AAAs previously treated by EVAR; this approach allows avoidance of surgical conversion, which is technical very challenging, with a high morbidity and mortality rate.

  7. Complex anatomy surrounding the left atrial posterior wall: analysis with 3D computed tomography.

    PubMed

    Maeda, Shingo; Iesaka, Yoshito; Uno, Kikuya; Otomo, Kiyoshi; Nagata, Yasutoshi; Suzuki, Kenji; Hachiya, Hitoshi; Goya, Masahiko; Takahashi, Atsushi; Fujiwara, Hideomi; Hiraoka, Masayasu; Isobe, Mitsuaki

    2012-01-01

    Few studies have explored the topographic anatomy of the esophagus, posterior wall of the left atrium (LA), or fat pads using multidetector computed tomography (MDCT) to prevent the risk of esophageal injury during atrial fibrillation (AF) ablation. MDCT was performed in 110 consecutive patients with paroxysmal or persistent AF before the ablation procedure to understand the anatomic relationship of the esophagus. Two major types of esophagus routes were demonstrated. Leftward (type A) and rightward (type B) routes were found in 90 and 10% of the patients, respectively. A type A route had a larger mean size of the LA than type B. The fat pad was identifiable at the level of the inferior pulmonary vein in 91% of the patients without any predominance of either type. The thickness of the fat pad was thinner in the patients with a dilated LA (>42 mm) than in those with a normal LA size (≤42 mm) (p = 0.01). The results demonstrated that the majority of cases had a leftward route of the esophagus. There was a close association between the LA dilatation and fat pad thinning. With a dilated LA, the esophagus may become easily susceptible to direct thermal injury during AF ablation. Visualization of the anatomic relationship may contribute to the prevention of the potential risk of an esophageal injury.

  8. Optic Strut and Para-clinoid Region – Assessment by Multi-detector Computed Tomography with Multiplanar and 3 Dimensional Reconstructions

    PubMed Central

    Ravikiran, S.R.; Kumar, Ashvini; Chavadi, Channabasappa; Pulastya, Sanyal

    2015-01-01

    Purpose To evaluate thickness, location and orientation of optic strut and anterior clinoid process and variations in paraclinoid region, solely based on multidetector computed tomography (MDCT) images with multiplanar (MPR) and 3 dimensional (3D) reconstructions, among Indian population. Materials and Methods Ninety five CT scans of head and paranasal sinuses patients were retrospectively evaluated with MPR and 3D reconstructions to assess optic strut thickness, angle and location, variations like pneumatisation, carotico-clinoid foramen and inter-clinoid osseous ridge. Results Mean optic strut thickness was 3.64mm (±0.64), optic strut angle was 42.67 (±6.16) degrees. Mean width and length of anterior clinoid process were 10.65mm (±0.79) and 11.20mm (±0.95) respectively. Optic strut attachment to sphenoid body was predominantly sulcal as in 52 cases (54.74%) and was most frequently attached to anterior 2/5th of anterior clinoid process, seen in 93 sides (48.95%). Pneumatisation of optic strut occurred in 23 sides. Carotico-clinoid foramen was observed in 42 cases (22.11%), complete foramen in 10 cases (5.26%), incomplete foramen in 24 cases (12.63%) and contact type in 8 cases (4.21%). Inter-clinoid osseous bridge was seen unilaterally in 4 cases. Conclusion The study assesses morphometric features and anatomical variations of paraclinoid region using MDCT 3D and multiplanar reconstructions in Indian population. PMID:26557589

  9. Functional Remodeling of Both Atria is Associated with Occurrence of Stroke in Patients with Paroxysmal and Persistent Atrial Fibrillation

    PubMed Central

    Tsao, Hsuan-Ming; Hu, Wei-Chih; Tsai, Ping-Huang; Lee, Chao-Lin; Wang, Hsueh-Han; Chang, Shih-Lin; Chao, Tze-Fan; Chen, Shih-Ann

    2017-01-01

    Background It is critical to recognize high risk patients who are prone to develop stroke in the management of atrial fibrillation (AF). The purpose of this study was to identify the determinants of AF related stroke by assessing the anatomical and functional remodeling of cardiac chambers. Methods We compared the cardiac structure and function of 28 consecutive patients with paroxysmal and persistent AF-related stroke with 69 patients with AF and 21 controls without stroke using contrast-enhanced 64-slice multi-detector computed tomography during sinus rhythm. Results The volume of left atrium (LA), LA appendage (LAA) and right atrium (RA) were significantly increased across the groups with sinus rhythm (SR), AF and AF-related stroke (p < 0.001 for each, respectively). The emptying fraction and booster-pump function of LA, LAA and RA were decreased across the groups (p < 0.001 for each). In addition, the left ventricular mass index was increased in AF related stroke (p = 0.003). Using multivariate analysis, increased age (p = 0.003), reduced booster-pump function of LA (p = 0.01), LAA (p < 0.001) and RA (p < 0.001) were shown to be independently associated with the occurrence of stroke. Conclusions The dilatation and contractile dysfunction of both atria are related to the development of stroke in patients with paroxysmal and persistent AF. Our results suggested that the use of substrate-based assessment may help improve risk stratification of stroke in patients with AF. PMID:28115807

  10. Whole body magnetic resonance angiography and computed tomography angiography in the vascular mapping of head and neck: an intraindividual comparison

    PubMed Central

    2014-01-01

    Introduction The aim of the study was to compare the detectability of neck vessels with contrast enhanced magnetic resonance angiography (MRA) in the setting of a whole-body MRA and multislice computed tomography angiography (CTA) for preoperative vascular mapping of head and neck. Methods In 20 patients MRA was performed prior to microvascular reconstruction of the mandible with osteomyocutaneous flaps. CTA of the neck served as the method of reference. 1.5 T contrast enhanced magnetic resonance angiograms were acquired to visualize the vascular structures of the neck in the setting of a whole-body MRA examination. 64-slice spiral computed tomography was performed with a dual-phase protocol, using the arterial phase images for 3D CTA reconstruction. Maximum intensity projection was employed to visualize MRA and CTA data. To retrieve differences in the detectability of vessel branches between MRA and CTA, a McNemar test was performed. Results All angiograms were of diagnostic quality. There were no statistically significant differences between MRA and CTA for the detection of branches of the external carotid artery that are relevant host vessels for microsurgery (p = 0.118). CTA was superior to MRA if all the external carotid artery branches were included (p < 0.001). Conclusions MRA is a reliable alternative to CTA in vascular mapping of the cervical vasculature for planning of microvascular reconstruction of the mandible. In the setting of whole-body MRA it could serve as a radiation free one-stop-shop tool for preoperative assessment of the arterial system, potentially covering both, the donor and host site in one single examination. PMID:24884580

  11. Changes in entrance surface dose in relation to the location of shielding material in chest computed tomography

    NASA Astrophysics Data System (ADS)

    Kang, Y. M.; Cho, J. H.; Kim, S. C.

    2015-07-01

    This study examined the effects of entrance surface dose (ESD) on the abdomen and pelvis of the patient when undergoing chest computed tomography (CT) procedure, and evaluated the effects of ESD reduction depending on the location of radiation shield. For CT scanner, the 64-slice multi-detector computed tomography was used. The alderson radiation therapy phantom and optically stimulated luminescence dosimeter (OSLD), which enabled measurement from low to high dose, were also used. For measurement of radiation dose, the slice number from 9 to 21 of the phantom was set as the test range, which included apex up to both costophrenic angles. A total of 10 OSLD nanoDots were attached for measurement of the front and rear ESD. Cyclic tests were performed using the low-dose chest CT and high-resolution CT (HRCT) protocol on the following set-ups: without shielding; shielding only on the front side; shielding only on the rear side; and shielding for both front and rear sides. According to the test results, ESD for both front and rear sides was higher in HRCT than low-dose CT when radiation shielding was not used. It was also determined that, compared to the set-up that did not use the radiation shield, locating the radiation shield on the front side was effective in reducing front ESD, while locating the radiation shield on the rear side reduced rear ESD level. Shielding both the front and rear sides resulted in ESD reduction. In conclusion, it was confirmed that shielding the front and rear sides was the most effective method to reduce the ESD effect caused by scatter ray during radiography.

  12. Clinical Applications of Three-Dimensional Visualization Model of Arteries Supplying the Extrahepatic Bile Duct for Patients with Biliary Obstruction.

    PubMed

    Jian, Yang; Haisu, Tao; Chihua, Fang; Yingfang, Fan; Nan, Xiang; Ning, Zeng; Jun, Liu; Wen, Zhu

    2017-01-01

    This study aimed to assess distribution characteristics and digital typing of arteries supplying the extrahepatic bile duct for patients with biliary obstruction, and evaluate the three-dimensional (3D) model in surgical decision-making. Forty-one patients with biliary obstruction were retrospectively evaluated. Clinical data obtained by 64-slice multidetector CT angiography scanning were introduced into Medical Image Three-Dimensional Visualization System; then, 3D model of extrahepatic bile duct and its supplying arteries were reconstructed. Based on the 3D model, the origination and bifurcations of the bile duct artery were observed, and the digital types established. Afterwards, plans for preoperative procedures were formulated. Finally, postoperative observations were performed and the biliary complications recorded in detail. The 3D model clearly displayed the origin, course, and distribution of individualized arteries supplying the extrahepatic bile duct, as well as variations. According to 3D model characteristics, the digital types were established. Blood supply to the superior segment of the extrahepatic bile duct encompassed 6 (14.6%), 17 (41.5%), 12 (29.3%), and 6 (14.6%) cases of Types IA, IB, IC, and II, respectively; meanwhile, blood supply to the inferior segment comprised 13 (31.7%), 13 (31.7%), 4 (9.8%), 7 (17.0%), and 4 (9.8%) cases of Types IA, IB, IC, II, and III, respectively. This classification helped in preoperative surgical planning and corroborated intraoperative findings. No postoperative biliary complications were recorded. The 3D model reconstructed using Medical Image Three-Dimensional Visualization System displayed individualized anatomical structures of the extrahepatic bile duct and associated blood supplying arteries, and could contribute to preoperative surgical planning.

  13. Computed tomography quality indexes: evaluation experience

    NASA Astrophysics Data System (ADS)

    Strocchi, Sabina; Vite, Cristina; Novario, Raffaele; Cacciatori, Marco; Frigerio, Giovanna; Conte, Leopoldo

    2009-02-01

    Aim of this work was to identify proper figures of merit (FoM's) to quantitatively and objectively assess the whole acquisition process of a CT image and to evaluate which are more significant. Catphan® phantom images where acquired with a 64 slices computed tomography system, with head and abdomen protocols. Automatic exposure modulation system was on, with different settings. We defined three FoM's (Q, Q1 and Q2) including image quality parameters and acquisition modalities; two of them (Q and Q1) include also a radiation dose quantity, the third (Q2) does not. Then we drew from these the comparable FoM's (CNR, Q1 *, Q2), that do not have dose in their definitions, in order to investigate how they depend on perceived image quality. The FoM's were evaluated for each series. At the same time, expert observers evaluated the number of low contrast inserts seen in the phantom' images. The considered CNR, Q1*, Q2 FoM's are linearly related to the perceived image quality for both the acquisition protocols (head: r2=0.91;0.94;0.91; abdomen: r2=0.93;0.93;0.85). Q and Q1 values analysis shows that these FoM's can distinguish between different acquisition modalities (head or abdomen) with statistically significant difference (p<0.05). The studied FoM's can be usefully used to quantitatively and objectively assess the whole CT image acquisition process. Those FoM's including also radiation dose (Q, Q1) can be used to objectively quantify the equilibrium between image quality and radiation dose for a certain acquisition modality.

  14. SU-E-I-62: Assessing Radiation Dose Reduction and CT Image Optimization Through the Measurement and Analysis of the Detector Quantum Efficiency (DQE) of CT Images Using Different Beam Hardening Filters

    SciTech Connect

    Collier, J; Aldoohan, S; Gill, K

    2014-06-01

    Purpose: Reducing patient dose while maintaining (or even improving) image quality is one of the foremost goals in CT imaging. To this end, we consider the feasibility of optimizing CT scan protocols in conjunction with the application of different beam-hardening filtrations and assess this augmentation through noise-power spectrum (NPS) and detector quantum efficiency (DQE) analysis. Methods: American College of Radiology (ACR) and Catphan phantoms (The Phantom Laboratory) were scanned with a 64 slice CT scanner when additional filtration of thickness and composition (e.g., copper, nickel, tantalum, titanium, and tungsten) had been applied. A MATLAB-based code was employed to calculate the image of noise NPS. The Catphan Image Owl software suite was then used to compute the modulated transfer function (MTF) responses of the scanner. The DQE for each additional filter, including the inherent filtration, was then computed from these values. Finally, CT dose index (CTDIvol) values were obtained for each applied filtration through the use of a 100 mm pencil ionization chamber and CT dose phantom. Results: NPS, MTF, and DQE values were computed for each applied filtration and compared to the reference case of inherent beam-hardening filtration only. Results showed that the NPS values were reduced between 5 and 12% compared to inherent filtration case. Additionally, CTDIvol values were reduced between 15 and 27% depending on the composition of filtration applied. However, no noticeable changes in image contrast-to-noise ratios were noted. Conclusion: The reduction in the quanta noise section of the NPS profile found in this phantom-based study is encouraging. The reduction in both noise and dose through the application of beam-hardening filters is reflected in our phantom image quality. However, further investigation is needed to ascertain the applicability of this approach to reducing patient dose while maintaining diagnostically acceptable image qualities in a

  15. Anatomic variation of the optic strut: classification schema, radiologic evaluation, and surgical relevance.

    PubMed

    Kerr, Robert G; Tobler, William D; Leach, James L; Theodosopoulos, Philip V; Kocaeli, Hasan; Zimmer, Lee A; Keller, Jeffrey T

    2012-12-01

    Objective Anatomic variability of the optic strut in location, orientation, and dimensions is relevant in approaching ophthalmic artery aneurysms and tumors of the anterior cavernous sinus, medial sphenoid wing, and optic canal. Methods In 84 dry human skulls, imaging studies were performed (64-slice computed tomography [CT] scanner, axial view, aligned with the zygomatic arch). Optic strut location related to the prechiasmatic sulcus was classified as presulcal, sulcal, postsulcal, and asymmetric. Morphometric analysis was performed. Results The optic strut was presulcal in 11.9% specimens (posteromedial margin bilaterally anterior to limbus sphenoidale), sulcal in 44% (posteromedial part adjacent to the sulcus's anterior two thirds bilaterally), postsulcal in 29.8% (posteromedial margin posterior to the sulcus's anterior two thirds), and asymmetric (left/right) in 14.3%. Optic strut length, width, and thickness measured 6.54 ± 1.69 mm, 4.23 ± 0.69 mm, and 3.01 ± 0.79 mm, respectively. Optic canal diameter was 5.14 ± 0.47 mm anteriorly and 4.79 ± 0.64 mm posteriorly. Angulation was flat (>45 degrees) in 13% or acute (<45 degrees) in 87% specimens. Conclusions Anatomical variations in the optic strut are significant in planning for anterior clinoidectomy and optic-canal decompression. Our optic strut classification considers these variations relative to the prechiasmatic sulcus on preoperative imaging.

  16. Anatomic Variation of the Optic Strut: Classification Schema, Radiologic Evaluation, and Surgical Relevance

    PubMed Central

    Kerr, Robert G.; Tobler, William D.; Leach, James L.; Theodosopoulos, Philip V.; Kocaeli, Hasan; Zimmer, Lee A.; Keller, Jeffrey T.

    2012-01-01

    Objective Anatomic variability of the optic strut in location, orientation, and dimensions is relevant in approaching ophthalmic artery aneurysms and tumors of the anterior cavernous sinus, medial sphenoid wing, and optic canal. Methods In 84 dry human skulls, imaging studies were performed (64-slice computed tomography [CT] scanner, axial view, aligned with the zygomatic arch). Optic strut location related to the prechiasmatic sulcus was classified as presulcal, sulcal, postsulcal, and asymmetric. Morphometric analysis was performed. Results The optic strut was presulcal in 11.9% specimens (posteromedial margin bilaterally anterior to limbus sphenoidale), sulcal in 44% (posteromedial part adjacent to the sulcus's anterior two thirds bilaterally), postsulcal in 29.8% (posteromedial margin posterior to the sulcus's anterior two thirds), and asymmetric (left/right) in 14.3%. Optic strut length, width, and thickness measured 6.54 ± 1.69 mm, 4.23 ± 0.69 mm, and 3.01 ± 0.79 mm, respectively. Optic canal diameter was 5.14 ± 0.47 mm anteriorly and 4.79 ± 0.64 mm posteriorly. Angulation was flat (>45 degrees) in 13% or acute (<45 degrees) in 87% specimens. Conclusions Anatomical variations in the optic strut are significant in planning for anterior clinoidectomy and optic-canal decompression. Our optic strut classification considers these variations relative to the prechiasmatic sulcus on preoperative imaging. PMID:24294561

  17. Tilted cone-beam reconstruction with row-wise fan-to-parallel rebinning

    NASA Astrophysics Data System (ADS)

    Hsieh, Jiang; Tang, Xiangyang

    2006-10-01

    Reconstruction algorithms for cone-beam CT have been the focus of many studies. Several exact and approximate reconstruction algorithms were proposed for step-and-shoot and helical scanning trajectories to combat cone-beam related artefacts. In this paper, we present a new closed-form cone-beam reconstruction formula for tilted gantry data acquisition. Although several algorithms were proposed in the past to combat errors induced by the gantry tilt, none of the algorithms addresses the scenario in which the cone-beam geometry is first rebinned to a set of parallel beams prior to the filtered backprojection. We show that the image quality advantages of the rebinned parallel-beam reconstruction are significant, which makes the development of such an algorithm necessary. Because of the rebinning process, the reconstruction algorithm becomes more complex and the amount of iso-centre adjustment depends not only on the projection and tilt angles, but also on the reconstructed pixel location. In this paper, we first demonstrate the advantages of the row-wise fan-to-parallel rebinning and derive a closed-form solution for the reconstruction algorithm for the step-and-shoot and constant-pitch helical scans. The proposed algorithm requires the 'warping' of the reconstruction matrix on a view-by-view basis prior to the backprojection step. We further extend the algorithm to the variable-pitch helical scans in which the patient table travels at non-constant speeds. The algorithm was tested extensively on both the 16- and 64-slice CT scanners. The efficacy of the algorithm is clearly demonstrated by multiple experiments.

  18. ESTIMATION OF CARDIAC CT ANGIOGRAPHY RADIATION DOSE TOWARD THE ESTABLISHMENT OF NATIONAL DIAGNOSTIC REFERENCE LEVEL FOR CCTA IN IRAN.

    PubMed

    Hosseini Nasab, Seyed Mohammad Bagher; Shabestani-Monfared, Ali; Deevband, Mohammad Reza; Paydar, Reza; Nabahati, Mehrdad

    2016-08-29

    In recent years, with the introduction of 64-slice CT and dual-source CT technology, coronary CT angiography (CCTA) has emerged as a useful diagnostic imaging modality as a non-invasive assessment of coronary heart disease. CT produces a larger radiation dose than other imaging tests and cardiac CT involves higher radiation dose with the advances in the spatial and temporal resolution. The aims of this study are patient dose assessment and establishment of national diagnostic reference level for CCTA in Iran. A questionnaire was sent to CCTA centers. Data for patient and CT protocols were obtained. The volumetric CT dose index (CTDIvol), dose length product (DLP) and total DLP were considered in the 32 cm standard body phantom. Calculation of estimated effective dose (ED) was obtained by multiplying the DLP by a conversion factor [k = 0.014 mSv (mGy·cm)(-1)]. Mean value of CTDIvol and DLP for CCTA was 50 mGy and 825 mGy·cm. The third quartile (75th) of the distribution of mean CTDIvol (66.54 mGy) and DLP (1073 mGy·cm) values was expressed as the diagnostic reference level (DRL) for CCTA in Iran. The median of ED was 10.26 mSv and interquartile range of ED was 7.08-15.03 mSv. A large variety in CTDIvol and DLP among CT scanner and different sites due to variability in CT parameter is noted. It seems that training could help to reduce patient's dose.

  19. High-performance computing and networking as tools for accurate emission computed tomography reconstruction.

    PubMed

    Passeri, A; Formiconi, A R; De Cristofaro, M T; Pupi, A; Meldolesi, U

    1997-04-01

    It is well known that the quantitative potential of emission computed tomography (ECT) relies on the ability to compensate for resolution, attenuation and scatter effects. Reconstruction algorithms which are able to take these effects into account are highly demanding in terms of computing resources. The reported work aimed to investigate the use of a parallel high-performance computing platform for ECT reconstruction taking into account an accurate model of the acquisition of single-photon emission tomographic (SPET) data. An iterative algorithm with an accurate model of the variable system response was ported on the MIMD (Multiple Instruction Multiple Data) parallel architecture of a 64-node Cray T3D massively parallel computer. The system was organized to make it easily accessible even from low-cost PC-based workstations through standard TCP/IP networking. A complete brain study of 30 (64x64) slices could be reconstructed from a set of 90 (64x64) projections with ten iterations of the conjugate gradients algorithm in 9 s, corresponding to an actual speed-up factor of 135. This work demonstrated the possibility of exploiting remote high-performance computing and networking resources from hospital sites by means of low-cost workstations using standard communication protocols without particular problems for routine use. The achievable speed-up factors allow the assessment of the clinical benefit of advanced reconstruction techniques which require a heavy computational burden for the compensation effects such as variable spatial resolution, scatter and attenuation. The possibility of using the same software on the same hardware platform with data acquired in different laboratories with various kinds of SPET instrumentation is appealing for software quality control and for the evaluation of the clinical impact of the reconstruction methods.

  20. Usefulness of Age and Gender in the Early Triage of Patients with Acute Chest Pain Having Cardiac Computed Tomographic Angiography

    PubMed Central

    Bamberg, Fabian; Truong, Quynh A.; Blankstein, Ron; Nasir, Khurram; Lee, Hang; Rogers, Ian S.; Achenbach, Stephan; Brady, Thomas J.; Nagurney, John T.; Reiser, Maximilian F.; Hoffmann, Udo

    2009-01-01

    To identify age- and gender- specific sub-populations of patients with acute chest pain in whom coronary CT angiography (CTA) yields the highest diagnostic benefit. Subjects with acute chest pain and an inconclusive initial evaluation (non-diagnostic electrocardiogram, negative cardiac biomarkers) underwent contrast-enhanced 64-slice CT coronary angiography as part of an observational cohort study. Independent investigators determined the presence of significant coronary stenosis (>50% luminal narrowing) and the occurrence of acute coronary syndrome (ACS) during index hospitalization. We determined diagnostic accuracy and impact on pretest probability of ACS using Bayes' theorem. Among 368 patients (52.7±12 age, 61% males), 8% had ACS. Presence of significant coronary stenosis by CT and the occurrence of ACS increased with age for both men and women (p<0.001). Cardiac CTA was highly sensitive and specific in women younger than 65 years of age (sensitivity: 100% and specificity >87%) and men younger than 55 years of age (sensitivity: 100% in <45 and 80% in 45-54 years old men; specificity: >88.2%). Moreover, in these patients coronary CTA led to restratification from low to high (for a positive CTA) or from low to very low risk (for a negative CTA). In contrast, a negative CTA result did not result in restratification to low risk category in women >65 and men >55 years of age. In conclusion, this analysis provides initial evidence that men <55 and women <65 might benefit more from cardiac CTA than elderly patients. Thus, age and gender may serve as simple criteria to appropriately select patients who may derive the greatest diagnostic benefit from coronary CTA in the setting of acute chest pain. PMID:19840556

  1. SU-E-I-25: Determining Tube Current, Tube Voltage and Pitch Suitable for Low- Dose Lung Screening CT

    SciTech Connect

    Williams, K; Matthews, K

    2014-06-01

    Purpose: The quality of a computed tomography (CT) image and the dose delivered during its acquisition depend upon the acquisition parameters used. Tube current, tube voltage, and pitch are acquisition parameters that potentially affect image quality and dose. This study investigated physicians' abilities to characterize small, solid nodules in low-dose CT images for combinations of current, voltage and pitch, for three CT scanner models. Methods: Lung CT images was acquired of a Data Spectrum anthropomorphic torso phantom with various combinations of pitch, tube current, and tube voltage; this phantom was used because acrylic beads of various sizes could be placed within the lung compartments to simulate nodules. The phantom was imaged on two 16-slice scanners and a 64-slice scanner. The acquisition parameters spanned a range of estimated CTDI levels; the CTDI estimates from the acquisition software were verified by measurement. Several experienced radiologists viewed the phantom lung CT images and noted nodule location, size and shape, as well as the acceptability of overall image quality. Results: Image quality for assessment of nodules was deemed unsatisfactory for all scanners at 80 kV (any tube current) and at 35 mA (any tube voltage). Tube current of 50 mA or more at 120 kV resulted in similar assessments from all three scanners. Physician-measured sphere diameters were closer to actual diameters for larger spheres, higher tube current, and higher kV. Pitch influenced size measurements less for larger spheres than for smaller spheres. CTDI was typically overestimated by the scanner software compared to measurement. Conclusion: Based on this survey of acquisition parameters, a low-dose CT protocol of 120 kV, 50 mA, and pitch of 1.4 is recommended to balance patient dose and acceptable image quality. For three models of scanners, this protocol resulted in estimated CTDIs from 2.9–3.6 mGy.

  2. Consideration of the Pathological Features of Pediatric Congenital Heart Diseases Which Are Ideally Suitable for Diagnosing With Multidetector-row CT

    PubMed Central

    Hayabuchi, Yasunobu; Inoue, Miki; Watanabe, Noriko; Sakata, Miho; Ohnishi, Tatsuya; Kagami, Shoji

    2011-01-01

    Background A lots of articles published regarding the usefulness of multidetector-row computed tomography (MDCT) in children with congenital heart disease (CHD) mostly describe that it can be an alternative to the invasive catheterization and angiography. The unique diagnostic features of this imaging modality have been largely ignored or disregarded. We described the pathological conditions that cannot be diagnosed by conventional angiography with cardiac catheterization but can be accurately diagnosed by MDCT. Methods We retrospectively reviewed non-ECG-gated MDCT images acquired from 452 children and young adults with CHD between 2005 and 2010 in our institute. In this article, we focused on the diagnostic advantages of MDCT, and indicated five pathological conditions. (1) When Blalock-Taussig shunt total occlusion prevents catheter insertion into the artificial vessel and angiography is ruled out, the peripheral pulmonary artery during the peripheral pulmonary artery can be imaged and diagnosed using MDCT based on blood flow supplied from many small collateral vessels originating from the aorta. (2) The location and protrusion of the device in the vessel after coil embolization to treat patent ductus arteriosus can be accurately visualized by virtual endoscopy using MDCT. (3) Calcification of patches, synthetic blood vessels, and other prostheses that is indistinct on conventional angiograms is clear on MDCT. (4) Simultaneous MDCT observations of the anatomical relationships between arterial and venous systems on the same image can clarify the detail diagnosis for surgical treatment. (5) Compression of the airways by the great vessels and pulmonary segmental emphysematous change can be diagnosed by MDCT. Results and Conclusions Among patients with CHD, MDCT is useful not only as a non-invasive alternative to conventional angiography, but also as a tool for specific morphological diagnoses. In the future, it will be necessary to accumulate experience in the

  3. Definition Study PHARUS

    DTIC Science & Technology

    1991-11-01

    distinguished in three main parts: - Antenna technology study, - Motion compensation study, - Realisation of a SAR testbed. The antenna technology study was...mainly focussed on the theory and design of patch antennae. Further the study included the theory of internal calibration of SAR systems, microwave...for the motion compensation in PHARUS. The study included the development of a SAR data simulator to evaluate the degradation of the SAR image by the

  4. Electrodynamic tether system study: Extended study

    NASA Technical Reports Server (NTRS)

    1988-01-01

    This document is the final report of a study performed by Ball Space Systems Division (BSSD) for the NASA Johnson Space Center under an extension to contract NAS9-17666. The tasks for the extended study were as follows: (1) Define an interface between the Electrodynamic Tether System (ETS) and the Space Station (SS); (2) Identify growth paths for the 100 kW ETS defined in the original study to a 200 kW level of performance; (3) Quantify orbit perturbations caused by cyclic day/night operations of a Plasma Motor/Generator (PMG) on the SS and explore methods of minimizing these effects; (4) Define the analyses, precursor technology, ground tests, and precursor demonstrations leading up to a demonstration mission for an electrodynamic tether system that would be capable of producing maneuvering thrust levels of 25 newtons; and (5) Propose a development schedule for the demonstration mission and preliminary cost estimates.

  5. Case study research.

    PubMed

    Taylor, Ruth; Thomas-Gregory, Annette

    2015-06-10

    This article describes case study research for nursing and healthcare practice. Case study research offers the researcher an approach by which a phenomenon can be investigated from multiple perspectives within a bounded context, allowing the researcher to provide a 'thick' description of the phenomenon. Although case study research is a flexible approach for the investigation of complex nursing and healthcare issues, it has methodological challenges, often associated with the multiple methods used in individual studies. These are explored through examples of case study research carried out in practice and education settings. An overview of what constitutes 'good' case study research is proposed.

  6. Southeastern Cancer Study Group: breast cancer studies

    SciTech Connect

    Smalley, R.V.; Bartolucci, A.A.; Moore, M.

    1983-12-01

    During the past 10 years, the Southeastern Cancer Study Group (SECSG) has been engaged in one major adjuvant study and three major advanced disease studies for patients with adenocarcinoma of the breast. The adjuvant study is demonstrating that six months of adjuvant CMF is the therapeutic equivalent of 12 months and that post-operative irradiation is of no added therapeutic benefit. In patients with advanced disease, a low dose 5 drug combination of CMFVP induces more objective responses than single agent 5FU, but improves survival only for those patients with liver metastases when compared to the sequential use of the same 5 single agents. The three drug combination, CAF, utilizing doxorubicin, induces more objective responses than low dose CMFVP, but it does not improve overall survival. The addition of a phase active combination, CAMELEON, (i.e., sequentially alternating therapy) of CAF has not improved the duration of disease control and survival for patients with liver metastases, lymphangitic and nodular lung metastases compared to CAF. Aggressive combination chemotherapeutic approaches to patients with advanced disease provide better and longer disease and tumor control but only marginal improvements in overall survival. Adding additional agents to a maximally tolerable regimen has not improved the therapeutic outcome.

  7. Inner City Education--Studying the Studies

    ERIC Educational Resources Information Center

    Halliburton, Warren J.

    1973-01-01

    Standing at the vantage point of the 1970s, the author looks back at some of the studies produced in the sixties, calling education and educators to task for the failings of the teaching-learning process in the inner city. (Author/JM)

  8. Spring 2006. Industry Study. Environment Study

    DTIC Science & Technology

    2006-01-01

    sustainability. 91 On the positive side, a 2005 survey found that an increasing number of business schools are offering courses in ethics, corporate...Studies Journal. Urbana: 2000.Vol.28, Iss. 3; pg. 576, 21 pgs. 92 World Resource Institute (WRI) (2005, October 19) Business Schools Respond to New

  9. Habitat Study. Transect Study. [Environmental Education Units.

    ERIC Educational Resources Information Center

    Minneapolis Independent School District 275, Minn.

    These three documents outline teaching activities intended to involve children with their environment. Suggested preliminary studies to motivate and familiarize elementary school students with some characteristics of organisms and their physical environment are followed by descriptions of class activities that may be undertaken in the field.…

  10. STUDY CARRELS, DESIGNS FOR INDEPENDENT STUDY SPACE.

    ERIC Educational Resources Information Center

    BEYNON, JOHN

    BECAUSE OF THE DEMAND FOR INDIVIDUALIZED INSTRUCTION, NEW SCHOOLS ARE BEING PLANNED WITH LESS CLASSROOM SPACE AND MORE LIBRARY AND INDIVIDUAL STUDY SPACES. THESE NEW SCHOOLS REQUIRE NEW KINDS OF FURNITURE DESIGNED PRIMARILY TO GIVE THE STUDENT A DEGREE OF PRIVACY RATHER THAN TO PROVIDE OPTIMUM CONTROL TO TEACHERS. THE CARREL, PREVIOUSLY USED…

  11. Tailored Barium Swallow Study

    MedlinePlus

    ... Esophagoscopy Gastroscopy Duodenoscopy (EGD) Hydrogen/Methane Breath Test Impedance and pH Study for Children Patency Test with Agile™ Patency Capsule Pediatric Endoscopy Impedance and pH Probe Study for Adults PillCam Small ...

  12. Esophagram (Barium Swallow Study)

    MedlinePlus

    ... Esophagoscopy Gastroscopy Duodenoscopy (EGD) Hydrogen/Methane Breath Test Impedance and pH Study for Children Patency Test with Agile™ Patency Capsule Pediatric Endoscopy Impedance and pH Probe Study for Adults PillCam Small ...

  13. The Study of Algae

    ERIC Educational Resources Information Center

    Rushforth, Samuel R.

    1977-01-01

    Included in this introduction to the study of algae are drawings of commonly encountered freshwater algae, a summary of the importance of algae, descriptions of the seven major groups of algae, and techniques for collection and study of algae. (CS)

  14. Chemical Industry Bandwidth Study

    SciTech Connect

    none,

    2006-12-01

    The Chemical Bandwidth Study provides a snapshot of potentially recoverable energy losses during chemical manufacturing. The advantage of this study is the use of "exergy" analysis as a tool for pinpointing inefficiencies.

  15. Toxicological study of Fluorosilicone

    SciTech Connect

    London, J.E.

    1986-05-01

    Fluorosilicone was nonirritating in rabbit eye application studies. Primary skin irritation studies in the rabbit showed the material to be a mild irritant. The materials did not induce sensitization in the guinea pig assay. 2 refs., 1 tab.

  16. Air Manganese Study

    EPA Pesticide Factsheets

    In November 2011 US EPA researchers conducted a health study of airborne manganese exposure in East Liverpool, Ohio. This Web site discusses preliminary results of the study and provides background and other related information.

  17. Case Study Teaching

    ERIC Educational Resources Information Center

    Herreid, Clyde Freeman

    2011-01-01

    This chapter describes the history of case study teaching, types of cases, and experimental data supporting their effectiveness. It also describes a model for comparing the efficacy of the various case study methods. (Contains 1 figure.)

  18. Satellite servicing economic study

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Previous studies have shown that satellite servicing is cost effective; however, all of these studies were of different formats, dollar year, learning rates, availability, etc. Therefore, it was difficult to correlate any useful trends from these studies. The reviewed study was initiated to correlate the economic data into a common data base, using a common set of assumptions. A selected set of existed funded programs was then analyzed to provide an independent analysis of the servicing options and potential economic benefits.

  19. Chesapeake Bay study

    NASA Technical Reports Server (NTRS)

    Love, W. J.

    1972-01-01

    The objectives and scope of the Chesapeake Bay study are discussed. The physical, chemical, biological, political, and social phenomena of concern to the Chesapeake Bay area are included in the study. The construction of a model of the bay which will provide a means of accurately studying the interaction of the ecological factors is described. The application of the study by management organizations for development, enhancement, conservation, preservation, and restoration of the resources is examined.

  20. Satellite servicing economic study

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Previous studies have shown that satellite servicing is cost effective; however, all of these studies were of different formats, dollar year, learning rates, availability, etc. Threfore, it was difficult to correlate any useful trends from these studies. The reviewed study was initiated to correlate the economic data into a common data base, using a common set of assumptions. A selected set of existed funded programs was then analyzed to provide an independent analysis of the servicing options and potential economic benefits.

  1. The Georgia Centenarian Study.

    ERIC Educational Resources Information Center

    Poon, Leonard W.; And Others

    1992-01-01

    Presents theoretical rationale, hypotheses, models, and methods and procedures of Georgia Centenarian Study, interdisciplinary study of oldest-old which began in 1988 to investigate adaptational characteristics of long-lived individuals. Introduces other articles in journal issue: first four reports of study, summarizing data collected in first…

  2. Why Study Italian?

    ERIC Educational Resources Information Center

    Haines, Charles

    1978-01-01

    One studies Italian for the same reason one studies any language--to become educated. Even more than for art and music, Italian is necessary for literature. Dante must be read, and in the original. Further, we study Italian to know our cultural roots and heritage. (AMH)

  3. Indian Studies Program.

    ERIC Educational Resources Information Center

    Peck, Cy, Sr.; And Others

    A product of the Indian Studies Curriculum Committee and the Indian Studies Staff, this manual on the Indians of Southeast Alaska constitutes a useable classroom tool designed for the cross-cultural program in the Juneau School District. Objectives of this Indian Studies Program are identified as: to increase knowledge, awareness, and positive…

  4. Cave Water Studies.

    ERIC Educational Resources Information Center

    O'Keefe, Elizabeth S.

    1996-01-01

    Describes a comparative study project where seventh grade students tested water samples from 10 cave sites that had been tested 24 years ago in a study that had attempted to determine if pollution in the environment had reached cave water. Discusses lab skills and some results of the study. (JRH)

  5. Studies in Clustering Theory

    DTIC Science & Technology

    1990-01-01

    colligative properties , and interpretinrg low-angle ligh-scattering data, no systematic studies of if, have been done before this work. Apcrecently carried out... properties of percolation models have been studied intensively,. These investigations have usually been confined to the’ study of idealized lattice

  6. Independent Study in Iowa.

    ERIC Educational Resources Information Center

    Idaho Univ., Moscow.

    This guide to independent study in Idaho begins with introductory information on the following aspects of independent study: the Independent Study in Idaho consortium, student eligibility, special needs, starting dates, registration, costs, textbooks and instructional materials, e-mail and faxing, refunds, choosing a course, time limits, speed…

  7. Defining (Conceptualizing) Social Studies.

    ERIC Educational Resources Information Center

    Shaver, James P.

    1990-01-01

    Critiques James Barth, Robert Barr, and Sam Shermis' three social studies traditions theory and National Commission on Social Studies task force report. Argues first falsely splits essential social studies components; second creates a curricular hodgepodge. Highlights need to consider values as both affective and cognitive and to create…

  8. Qualitative Studies: Historiographical Antecedents.

    ERIC Educational Resources Information Center

    Mills, Rilla Dean

    This paper provides an overview of qualitative studies' antecedents among historiographers and of the positivist tide which nearly engulfed them. Humans live by interpretations. The task of social science--the basic task of qualitative studies--is to study these interpretations so that we can better understand the meanings which people use to…

  9. Studying to Learn.

    ERIC Educational Resources Information Center

    Air Univ., Maxwell AFB, AL.

    This booklet was prepared in response to a demand from Air Force Officers returning to academic study after being out of school for several years. Its main purpose is to help returning veterans learn how to study. The guide is divided into three sections: (1) the "Reconnaissance-Read-Recall" (RRR) system of study, (2) concepts in "How We Learn,"…

  10. Vacation Study Abroad.

    ERIC Educational Resources Information Center

    Howard, E. Marguerite, Ed.

    A guide to summer study abroad is presented with information on how to plan rewarding summer study and travel overseas. Concise descriptions of over 1300 postsecondary study programs worldwide (in over 65 countries) sponsored by U.S. and foreign universities and institutions are included with details on program sponsor and name, location, dates,…

  11. American Studies through Folktales.

    ERIC Educational Resources Information Center

    Pedersen, E. Martin

    1992-01-01

    American studies is a combination of fields such as literature, history, philosophy, politics, and economics. This publication examines how the different fields of study relate to American studies through folklore or folktales. The use of folktales can provide better illustrations and understandings of U.S. individuals' heritage and evolution.…

  12. Social Psychoanalytic Disability Studies

    ERIC Educational Resources Information Center

    Goodley, Dan

    2011-01-01

    This paper explores connections and tensions between psychoanalysis and disability studies. The first part of the paper considers contemporaneous engagements with the psyche by a number of disability studies writers. These scholars have remained accountable to a politicised disability studies but have pushed for critical encounters with the…

  13. Home Start Evaluation Study.

    ERIC Educational Resources Information Center

    High/Scope Educational Research Foundation, Ypsilanti, MI.

    Case studies of eight Home Start programs are given as the third section of an evaluation study. Communities involved are Binghamton, New York; Franklin, North Carolina; Cleveland, Ohio; Harrogate, Tennessee; Houston, Texas; Weslaco, Texas; Millville, Utah; Parkersburg, West Virginia. Although each study varies in format, each describes in detail…

  14. 78 FR 52929 - Scientific Information Request on Imaging Tests for the Diagnosis and Staging of Pancreatic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-27

    ..., PET-CT, MRI) for diagnosis of pancreatic adenocarcinoma in adults with suspicious symptoms? a. What is... effectiveness of imaging techniques (e.g., MDCT angiography 3D reconstruction, other MDCT, EUS-FNA, PET-CT, MRI..., EUS-FNA, PET- CT, MRI) when used to diagnose and/or stage pancreatic adenocarcinoma? a. How...

  15. Update on the imaging diagnosis of otosclerosis.

    PubMed

    Gredilla Molinero, J; Mancheño Losa, M; Santamaría Guinea, N; Arévalo Galeano, N; Grande Bárez, M

    2016-01-01

    Otosclerosis is a primary osteodystrophy of the temporal bone that causes progressive conductive hearing loss. The diagnosis is generally clinical, but multidetector CT (MDCT), the imaging technique of choice, is sometimes necessary. The objective of this article is to systematically review the usefulness of imaging techniques for the diagnosis and postsurgical assessment of otosclerosis, fundamentally the role of MDCT, to decrease the surgical risk.

  16. The 'mill-wheel' murmur and computed tomography of intracardiac air emboli.

    PubMed

    Rubal, Bernard J; Leon, Alisa; Meyers, Belinda L; Bell, Christopher M

    2009-05-01

    The 'water-wheel' or 'mill-wheel' murmur is classically associated with large intracardiac air emboli and described as a "characteristic splashing auscultatory sound due to the presence of gas in the cardiac chambers." We used 64-slice computed tomography (slice thickness, 0.5 mm; revolution time, 400 msec) and 3D fly-through software imagery to capture previously unreported intracardiac air-blood interface dynamics associated with this murmur and ineffective right ventricular contraction in a porcine model.

  17. Mars Aerocapture Systems Study

    NASA Technical Reports Server (NTRS)

    Wright, Henry S.; Oh, David Y.; Westhelle, Carlos H.; Fisher, Jody L.; Dyke, R. Eric; Edquist, Karl T.; Brown, James L.; Justh, Hilary L.; Munk, Michelle M.

    2006-01-01

    Mars Aerocapture Systems Study (MASS) is a detailed study of the application of aerocapture to a large Mars robotic orbiter to assess and identify key technology gaps. This study addressed use of an Opposition class return segment for use in the Mars Sample Return architecture. Study addressed mission architecture issues as well as system design. Key trade studies focused on design of aerocapture aeroshell, spacecraft design and packaging, guidance, navigation and control with simulation, computational fluid dynamics, and thermal protection system sizing. Detailed master equipment lists are included as well as a cursory cost assessment.

  18. Advanced Clothing Studies

    NASA Technical Reports Server (NTRS)

    Orndoff, Evelyne; Poritz, Darwin

    2014-01-01

    All human space missions require significant logistical mass and volume that add an unprecedented burden on longduration missions beyond low-Earth orbit. For these missions with limited cleaning resources, a new wardrobe must be developed to reduce this logistical burden by reducing clothing mass and extending clothing wear. The present studies have been undertaken, for the first time, to measure length of wear and to assess the acceptance of such extended wear. Garments in these studies are commercially available exercise T-shirts and shorts, routine-wear T-shirts, and longsleeved pullover shirts. Fabric composition (cotton, polyester, light-weight, superfine Merino wool, modacrylic, cotton/rayon, polyester/Cocona, modacrylic/Xstatic, modacrylic/rayon, modacrylic/lyocell/aramid), construction (open knit, tight knit, open weave, tight weave), and finishing treatment (none, quaternary ammonium salt) are the independent variables. Eleven studies are reported here: five studies of exercise T-shirts, three of exercise shorts, two of routine wear Tshirts, and one of shirts used as sleep-wear. All studies are conducted in a climate-controlled environment, similar to a space vehicle's. For exercise clothing, study participants wear the garments during aerobic exercise. For routine wear clothing, study participants wear the T-shirts daily in an office or laboratory. Daily questionnaires collected data on ordinal preferences of nine sensory elements and on reason for retiring a used garment. Study 1 compares knitted cotton, polyester, and Merino exercise T-shirts (61 participants), study 2, knitted polyester, modacrylic, and polyester/Cocona exercise T-shirts (40 participants), study 3, cotton and polyester exercise shorts, knitted and woven (70 participants), all three using factorial experimental designs with and without a finishing treatment, conducted at the Johnson Space Center, sharing study participants. Study 4 compares knitted polyester and ZQ Merino exercise T

  19. Mysore study: A study of suicide notes

    PubMed Central

    Namratha, P.; Kishor, M.; Sathyanarayana Rao, T. S.; Raman, Rajesh

    2015-01-01

    Background: Suicide is one of the leading causes of preventable deaths. Recent data suggest South India as one of the regions with highest suicide rates in the world. In 2013, 134,799 people committed suicide in India according to the statistics released by the National Crime Records Bureau. Suicide note is one of the most important sources to understand suicide, which may be beneficial in suicide prevention. Studies on suicidal notes from this part of the world are sparse. Objective: The aim was to study the themes in suicide notes that might be useful in prevention strategies. Materials and Methods: A descriptive study of all suicide notes of those individuals who committed suicide between 2010 and 2013 available with Police Department, Mysore district was obtained and analyzed. Results: A total of 22 suicide note were available. A majority of suicide note was in age group of 16–40 years (86%) and most were men (59%). All suicide notes were handwritten, the majority (70%) in regional language Kannada. Length of notes varied from just few words to few pages. Contents of suicide notes included apology/shame/guilt (80%), love for those left behind (55%) and instruction regarding practical affairs (23%). Most have blamed none for the act (50%). 23% mentioned that they are committing suicide to prove their innocence. 32% mentioned a last wish. Conclusion: The majority of suicidal note contained “guilt” which is a strong indicator of possible depression in deceased. Creating awareness about suicide among public and ensuring access to professionals trained in suicide prevention is need of the hour in this part of the world. PMID:26816426

  20. Teleoperator Human Factors Study

    NASA Technical Reports Server (NTRS)

    1986-01-01

    An investigation of the spectrum of space teleoperation activities likely in the 1985 to 1995 decade focused on the resolution of critical human engineering issues and characterization of the technology effect on performance of remote human operators. The study began with the identification and documentation of a set of representative reference teleoperator tasks. For each task, technology, development, and design options, issues, and alternatives that bear on human operator performance were defined and categorized. A literature survey identified existing studies of man/machine issues. For each teleoperations category, an assessment was made of the state of knowledge on a scale from adequate to void. The tests, experiments, and analyses necessary to provide the missing elements of knowledge were then defined. A limited set of tests were actually performed, including operator selection, baseline task definition, control mode study, lighting study, camera study, and preliminary time delay study.

  1. Future Spacelift Requirements Study

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This study addresses future space applications and the derived requirements these potential applications will have on future spacelift systems. This NASA sponsored activity is a comprehensive study of potential missions including those of the military, civil, and commercial users. The study objectively evaluated the key architectural requirements for future launch systems. The results of this study are technical, economic, and policy analyses of future spacelift systems. It is intended to assist NASA and DOD decision-makers in planning technical investments and establishing policy for future U.S. spacelift systems.

  2. Research Studies & Networks

    Cancer.gov

    These epidemiological studies may assist in evaluating associations between certain pharmaceuticals and disease risk and contain detailed information on pharmaceutical use and disease risk, including cancer.

  3. Human exploration mission studies

    NASA Technical Reports Server (NTRS)

    Cataldo, Robert L.

    1989-01-01

    The Office of Exploration has established a process whereby all NASA field centers and other NASA Headquarters offices participate in the formulation and analysis of a wide range of mission strategies. These strategies were manifested into specific scenarios or candidate case studies. The case studies provided a systematic approach into analyzing each mission element. First, each case study must address several major themes and rationale including: national pride and international prestige, advancement of scientific knowledge, a catalyst for technology, economic benefits, space enterprise, international cooperation, and education and excellence. Second, the set of candidate case studies are formulated to encompass the technology requirement limits in the life sciences, launch capabilities, space transfer, automation, and robotics in space operations, power, and propulsion. The first set of reference case studies identify three major strategies: human expeditions, science outposts, and evolutionary expansion. During the past year, four case studies were examined to explore these strategies. The expeditionary missions include the Human Expedition to Phobos and Human Expedition to Mars case studies. The Lunar Observatory and Lunar Outpost to Early Mars Evolution case studies examined the later two strategies. This set of case studies established the framework to perform detailed mission analysis and system engineering to define a host of concepts and requirements for various space systems and advanced technologies. The details of each mission are described and, specifically, the results affecting the advanced technologies required to accomplish each mission scenario are presented.

  4. Study design: the basics.

    PubMed

    Lim, Hyun Ja; Hoffmann, Raymond G

    2007-01-01

    In biomedical research, meaningful conclusions can only be drawn based on data collected from a valid scientific design using appropriate statistical methods. Therefore, the selection of an appropriate study design is important in order to provide an unbiased and scientific evaluation of the research questions. In this chapter, the different kinds of experimental studies commonly used in biology and medicine are introduced. A brief survey of basic experimental study designs, randomization, blinding, possible biases, issues in data analysis, and interpretation of the study results are mainly provided.

  5. Communications systems checkout study

    NASA Technical Reports Server (NTRS)

    Ginter, W. G.

    1972-01-01

    The results and conclusions of an engineering study of Space Station communications subsystem checkout are reported. The primary purpose of the study is to recommend specific guidelines and constraints for the design and utilization of the communications subsystem leading to a practical and effective means of onboard checkout implementation. Major study objectives are as follows: (1) identify candidate communications subsystem checkout concepts, (2) determine implementation impacts of feasible concepts, (3) evaluate practicality and effectiveness of alternative concepts, (4) propose baseline modifications to accommodate preferred concepts, and (5) recommend areas for additional investigation. In addition, study results are interpreted, where appropriate, in terms of their applicability to checkout of Shuttle-Orbiter communications subsystem.

  6. Xenia Spacecraft Study

    NASA Technical Reports Server (NTRS)

    Hopkins, Randy

    2009-01-01

    This slide presentation reviews the proposed design for the Xenia mission spacecraft. The goal of this study is to perform a mission concept study for the mission. Included in this study are: the overall ground rules and assumptions (GR&A), a mission analysis, the configuration, the mass properties, the guidance, Navigation and control, the proposed avionics, the power system, the thermal protection system, the propulsion system, and the proposed structures. Conclusions from the study indicate that the observatory fits within the Falcon 9 mass and volume envelope for launching from Omelek, the pointing, slow slewing, and fast slewing requirements and the thermal requirements are met.

  7. SETDA Case Studies 2012

    ERIC Educational Resources Information Center

    State Educational Technology Directors Association, 2012

    2012-01-01

    The State Educational Technology Directors Association (SETDA) published a series of case studies from 28 states to showcase examples of how ARRA EETT ("American Recovery and Reinvestment Act of 2009 Enhancing Education Through Technology") grant funds have impacted teaching and learning. SETDA collected data for the case studies through…

  8. Home Study Advertising Handbook.

    ERIC Educational Resources Information Center

    Lambert, Michael P., Ed.; Welch, Sally R., Ed.

    This handbook contains a collections of nine articles on the subject of direct-response advertising. The handbook gives advice on how to create effective advertisements for home study courses. The nine articles are the following: "Overview of Home Study Advertising in the 1990s" (Michael P. Lambert); "Ad Features that Sell"…

  9. Attribution Studies: A Review

    ERIC Educational Resources Information Center

    Rogove, Linda

    1972-01-01

    Stylistic analysis or attribution study is a very different kind of indexing. Instead of indexing subjects, it measures such things as the frequencies of common words such as and" and the". These studies reveal a great deal about consistency, methodology, and the approaches used for documents in the humanities. (41 references) (Author/NH)

  10. Library Studies I Workbook.

    ERIC Educational Resources Information Center

    Frost, William J.

    Developed for use in the Library Studies I component of the Library Studies Program at Bloomsburg University (Pennsylvania), this self-paced workbook is intended to acquaint students with the Harvey A. Andruss Library and help them develop information-seeking skills. The workbook is designed to be used in conjunction with an exercise book, and…

  11. Introduction to Childhood Studies

    ERIC Educational Resources Information Center

    Kehily, Mary Jane, Ed.

    2004-01-01

    Educationalists and social scientists are increasingly interested in childhood as a distinct social category, and Childhood Studies is now a recognized area of research and analysis. This book brings together the key themes of Childhood Studies in a broad and accessible introduction for students and practitioners working in this field.…

  12. Lesson Study: Beyond Coaching

    ERIC Educational Resources Information Center

    Lewis, Catherine; Perry, Rebecca; Foster, David; Hurd, Jacqueline; Fisher, Linda

    2011-01-01

    The authors assert that lesson study--a collaborative, teacher-led approach to learning from practice--offers a deeper, broader, more sustainable method of improving teacher practice than one-on-one coaching does. In lesson study, teachers and coaches of all levels of experience can work together, each bringing his or her own professional…

  13. Case Study: Challenging Change.

    ERIC Educational Resources Information Center

    May, Steven K.

    2003-01-01

    Discusses a case study involving organizational change and its effect on employees. Presents three responses to the case study: "Paradox of Ordering Change: I Insist That We Work as a Team" (Paaige K. Turner); "Managing Change Is Managing Meaning" (Greg Hearn and Abraham Ninan); and "The Psychodynamics of an Organizational Change Initiative"…

  14. Asterisk Grade Study Report.

    ERIC Educational Resources Information Center

    Kokorsky, Eileen A.

    A study was conducted at Passaic County Community College (PCCC) to investigate the operation of a grading system which utilized an asterisk (*) grade to indicate progress in a course until a letter grade was assigned. The study sought to determine the persistence of students receiving the "*" grade, the incidence of cases of students receiving…

  15. Studying the Future

    ERIC Educational Resources Information Center

    Delahanty, B. David

    1973-01-01

    Four means of studying the future are discussed: through extrapolation, or the study of trends; by writing scenarios of the future; through the use of games and through the utilization of the Delphi technique, making predictions in a specific field over a period of time. (JB)

  16. Advanced planetary studies

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Results of planetary advanced studies and planning support are summarized. The scope of analyses includes cost estimation research, planetary mission performance, penetrator advanced studies, Mercury mission transport requirements, definition of super solar electric propulsion/solar sail mission discriminators, and advanced planning activities.

  17. Study Canada: International Outlook.

    ERIC Educational Resources Information Center

    Monahan, Robert L.; And Others

    This self-contained unit of study on Canada is one of a series which can be used to supplement secondary level courses of social studies, contemporary world problems, government, history, and geography. Developed by teachers, the unit focuses on international relations. A comparative approach is used which stresses understanding Canada from…

  18. French Studies: A Bibliography.

    ERIC Educational Resources Information Center

    Markey, William L., Comp.

    A bibliography of materials relating to French language and area studies includes citations of bibliographies, books, articles, and general and specialized reference materials in French and English in these categories: general reference guides; guides to French studies; style manuals; research methodology and handbooks; library resources;…

  19. Interagency Depainting Study Status

    NASA Technical Reports Server (NTRS)

    Clark-Ingram, Marceia; Cook, Beth

    1999-01-01

    This document discusses coating removal in general. Sections of this presentation include: regulatory background, the initial parameters of the study, the current parameters of the study, stages in each sequence, preparation of the test specimen, material evaluation testing, chemical stripping, CO2 blasting, Flashjet coating removal, plastic media blasting, sodium bicarbonate wet stripping, water stripping, and wheat starch stripping.

  20. Social Studies and Feminism.

    ERIC Educational Resources Information Center

    Noddings, Nel

    1992-01-01

    Discusses feminism and its role in social studies. Suggests that adding a few female names and faces has not changed the inherent masculinity of the culture. Argues that women's contributions are overlooked because they do not fit the male model of achievement. Suggests that women's culture must be articulated in the social studies. (DK)

  1. Brine stability study

    SciTech Connect

    Gary Garland

    2015-04-15

    This is a study of the brine formulations that we were using in our testing were stable over time. The data includes charts, as well as, all of the original data from the ICP-MS runs to complete this study.

  2. Spacing Studies in Peppers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Higher plant stand densities usually result in greater pepper fruit yields. While the impact of stand density on yield has been studied for bell and non-bell peppers, but very little information exists regarding implications on pesticide efficacy. The objective of these studies was to determine th...

  3. Pyridostigmine Synergistic Toxicity Study.

    DTIC Science & Technology

    1995-05-31

    study was separated into two phases. The first (Phase I) determined the acute oral lethal dose - response relationship of each compound with the vehicle...propylene glycol. The second (Phase II) was divided into two portions. One portion (positive control) was a dose - response study using probit units

  4. Distance Learning Case Studies.

    ERIC Educational Resources Information Center

    Barker, Bruce O.

    The Office of Technology Assessment authorized a series of case studies in 1989 to investigate how technologies, services, and programs are implemented in distance education projects. The studies were also intended to look at the role of local, state, and federal agencies, and other public and private entities in providing educational services to…

  5. Energy conversion alternatives study

    NASA Technical Reports Server (NTRS)

    Shure, L. T.

    1979-01-01

    Comparison of coal based energy systems is given. Study identifies and compares various advanced energy conversion systems using coal or coal derived fuels for baselaoad electric power generation. Energy Conversion Alternatives Study (ECAS) reports provede government, industry, and general public with technically consistent basis for comparison of system's options of interest for fossilfired electric-utility application.

  6. Destination: Lesotho. Study Guide.

    ERIC Educational Resources Information Center

    Sheffield, Elise Sprunt

    This study guide was developed for teachers and students participating in the Peace Corps World Wise Schools program. The primary purpose of the study guide series is to enhance each class's correspondence with its Peace Corps Volunteer and to help students gain a greater understanding of regions and cultures different from their own. The specific…

  7. International Study Tour Groups

    ERIC Educational Resources Information Center

    O'Reilly, Frances L.; Matt, John J.; McCaw, William P.; Kero, Patty; Stewart, Courtney; Haddouch, Reda

    2014-01-01

    Using the context of international study tour groups, this study examined the personal and professional transformation that occurred among host faculty and staff at The University of Montana-Missoula as a result of their interactions with traveling academics from other countries. Data were collected from participant responses (n = 27) using a…

  8. Studies of Supervisory Behavior.

    ERIC Educational Resources Information Center

    Sistrunk, Walter E.

    A series of supervisory behavior studies that began at Mississippi State University in 1980 are summarized. The studies were instigated because of interest in effective supervision and dissatisfaction with an indepth literature search of supervision literature. The theories disclosed were fragmentary, contradictory, and impractical for use by…

  9. Study Skills and Learning.

    ERIC Educational Resources Information Center

    Marton, Ference; Svensson, Lennart

    1976-01-01

    The series of research studies contained in this project emphasize the central position of the learning process in research into teaching. The main studies under the project were based on four sets of material collected in the course of three academic years. A number of supplementary collections and processings of other material were also…

  10. Cuban Studies Newsletter.

    ERIC Educational Resources Information Center

    Pittsburgh Univ., PA. University Center for International Studies.

    This is the first issue of the Cuban Studies Newsletter, a biannual publication designed to provide comprehensive and timely communication among those interested in Cuban Studies. The purpose of the newsletter stated in a recommendation by the International Conference on Cuban Bibliography and Acquisitions, April, 1970, is to promote the scholarly…

  11. Bradford School Study

    ERIC Educational Resources Information Center

    Geiger, John O.; Torge, Herman

    This report presents a study of Bradford (Ohio) High School, a four-year school of 200-300 students that has experienced significant recent declines in grades 11 and 12 enrollment as many students have begun attending a nearby Joint Vocational School. Primary purpose of the study is to aid school officials in learning what draws Bradford students…

  12. European Study Tour Guidelines.

    ERIC Educational Resources Information Center

    Mitchell, Vicki L.; Mitchell, Kenneth E.

    Guidelines are presented for planning and financing European study tours at the community college level. First, a rationale for incorporating study tours of Europe within the community college curriculum is presented and the benefits of such tours in providing students with experiences they could not normally have are outlined. Next, the paper…

  13. Theorizing Iberian Studies

    ERIC Educational Resources Information Center

    Newcomb, Robert Patrick

    2015-01-01

    A growing number of scholars invested in Iberian Studies are asking how peninsular literary and cultural studies might be reimagined, and reinvigorated, by placing the Spanish and Portuguese canons into critical dialogue with each other, and with Galician, Catalan, Basque/Euskadi, and Latin American and North African immigrant writers, cultural…

  14. Qualitative Studies in HRD.

    ERIC Educational Resources Information Center

    1999

    The first of the four papers in this symposium, "What Is It Like To Be an Independent HRD Consultant?" (Alexander Ardishvili), reports on a phenomenological study that investigated the experience of being an independent HRD (human resource development) consultant through interviews with 10 successful HRD consultants. The study identified eight…

  15. Black Studies Perspectives

    ERIC Educational Resources Information Center

    Adams, Russell L.

    1977-01-01

    Discusses the proposition that the black studies movement is but a continuing aspect of our general battle for survival and liberation in a fluctuatingly hostile environment, and that a part of what is seen today in the black studies movement is but a fluctuation in a fight and an expression of black collective awareness dating back to the…

  16. Studies of Unwanted Babies

    ERIC Educational Resources Information Center

    Sigal, John J.

    2004-01-01

    Comments on the article by David, Dytrych, and Matejcek (see record 2003-03645-009) which showed the long-term negative psychological effects of unwantedness, up to 35 years after birth. The author states that despite their contention, this is not the only such long-term study. The authors briefly discuss other longitudinal studies of children…

  17. 1990 NACUBO Endowment Study.

    ERIC Educational Resources Information Center

    National Association of College and University Business Officers, Washington, DC.

    The 1990 Endowment Study of America's colleges and universities covered a broad variety of endowment issues of concern to trustees and administrators. The survey was mailed to 450 institutions and 369 institutions (82%) responded. Results of the study showed that 367 institutions had endowment assets totaling $60.1 billion. For fiscal year 1990,…

  18. Community Services Study.

    ERIC Educational Resources Information Center

    Sacks, Patricia Ann; And Others

    The purpose of this study is to describe the public services extended by the Lehigh Valley Association of Independent College Libraries (LVAIC) to the member colleges and local communities. The study includes observations on the data and the apparent needs of library users in the area, and concludes with several prescriptive recommendations. This…

  19. Study of strange nuclei

    SciTech Connect

    Chrien, R.E.

    1982-12-08

    A brief history of the discovery of hypernuclei is given and some recent hypernuclei studies are described. Topics include the study of p-shell hypernuclei, /sup 12/C (K/sup -/, ..pi../sup -/) experiment, and hypernuclear gamma rays. 13 references. (WHK)

  20. [Cross-over studies].

    PubMed

    Bonten, Tobias N; Siegerink, Bob; van der Bom, Johanna G

    2013-01-01

    Randomized, parallel group clinical trials often require large groups of patients; this is expensive and takes time. A randomized cross-over trial can be an efficient and more affordable alternative. A cross-over design can be used to study chronic disorders in which treatments have temporary effects. Participants receive all treatments in consecutive periods and outcomes are measured after every period. In general, only a quarter of the total group size is needed for cross-over studies compared with parallel group studies. Results can be affected by period-effects and carry-over-effects, which can be prevented through randomization and a wash-out period of sufficient length. The dropping-out of participants has more negative consequences for cross-over studies than for parallel group studies.

  1. Interagency Array Study Report

    NASA Technical Reports Server (NTRS)

    Wayland, J. W.; Ruskin, A. M.; Bathker, D. A.; Rydgig, R. C.; Brown, D. W.; Madsen, B. D.; Clauss, R. C.; Levy, G. S.; Kerridge, S. J.; Klein, M. J.

    1983-01-01

    The interagency array study that was convened in early 1982 to determine which of the world's large radio reception facilities might be feasibly and beneficially enlisted to help support the Voyager encounters at Uranus (1986) and Neptune (1989), and also to examine the future for such similar events and options as might appear is discussed. A similar but more specific study of the Parkes Radio Telescope at Uranus Encounter was just then being completed with a strong positive recommendation, and formed the foundation of the broader study. The approach, driving considerations, and outcome of the interagency array study are discussed. The recommendations of the study team concentrated upon the Voyager Encounters are: specifically to develop Parkes for the Uranus Encounter, while pursuing related Advanced Systems development work with the Owens Valley Radio Observatory, and to seek support for the Neptune Encounter from Parkes, the Very Large Array near Socorro, Mexico, and the Japanese institute of Space and Astronautical Sciences 64 meter station.

  2. Reservoir stability studies

    SciTech Connect

    Doherty, T.J.

    1981-07-01

    The objective of the reservoir stability studies project is to develop stability criteria for large underground reservoirs in salt domes, hard rock caverns, and porous rock structures for air storage in utility applications. Because reservoir stability was deemed crucial to commercialization of compressed air energy storage (CAES) systems this project has received major emphasis in the early phases of the overall CAES program. A long term plan, including state-of-the-art assessment, numerical model development and experimental studies culminating in field research, as necessary, was formulated. This plan, initiated in 1977, has been completed during FY-1981 to the stage of specific experimental studies and field research. Activities within this project during FY-1981 have included completion of site specific geotechnical design evaluations using methodologies developed to assess hard rock cavern stability, implementation of in-mine research to evaluate numerical and laboratory study conclusions on the response of domal salt, and preparation of integrated laboratory and field study facilities to assess developed predictive methods and determine in situ response of a porous media reservoir to air injection. The major activity in the project has been the field study component of the porous media studies. Accomplishments there have included completion of exploration, permitting and leasing, operation contractor selection and negotiation, and initiation of procurement and construction for an FY-1982 test initiation. A major program milestone, drilling of the injection withdrawal well for this test, was completed ahead of schedule.

  3. Tokamak reactor studies

    SciTech Connect

    Baker, C.C.

    1981-01-01

    This paper presents an overview of tokamak reactor studies with particular attention to commercial reactor concepts developed within the last three years. Emphasis is placed on DT fueled reactors for electricity production. A brief history of tokamak reactor studies is presented. The STARFIRE, NUWMAK, and HFCTR studies are highlighted. Recent developments that have increased the commercial attractiveness of tokamak reactor designs are discussed. These developments include smaller plant sizes, higher first wall loadings, improved maintenance concepts, steady-state operation, non-divertor particle control, and improved reactor safety features.

  4. Studying aging in Drosophila.

    PubMed

    He, Ying; Jasper, Heinrich

    2014-06-15

    Drosophila melanogaster represents one of the most important genetically accessible model organisms for aging research. Studies in flies have identified single gene mutations that influence lifespan and have characterized endocrine signaling interactions that control homeostasis systemically. Recent studies have focused on the effects of aging on specific tissues and physiological processes, providing a comprehensive picture of age-related tissue dysfunction and the loss of systemic homeostasis. Here we review methodological aspects of this work and highlight technical considerations when using Drosophila to study aging and age-related diseases.

  5. [Case and studies].

    PubMed

    Schubert, András

    2015-11-15

    Case studies and case reports form an important and ever growing part of scientific and scholarly literature. The paper deals with the share and citation rate of these publication types on different fields of research. In general, evidence seems to support the opinion that an excessive number of such publications may negatively influence the impact factor of the journal. In the literature of scientometrics, case studies (at least the presence of the term "case study" in the titles of the papers) have a moderate share, but their citation rate is practically equal to that of other publication types.

  6. Variability study for saltstone

    SciTech Connect

    Harbour, J. R.; Edwards, T. B.; Hansen, E. K.; Williams, V. J.

    2005-10-01

    This report is a summary of the bench-scale experimental studies performed by the Savannah River National Laboratory (SRNL) for Waste Solidification Engineering (WSE) to establish the viability of a grout-based variability study. In order for a variability study to be useful, the property measurements of the fresh and cured Saltstone must be reproducible with an inherent variation that is small compared to the changes in the properties measured over the expected range of variability for a Salt Batch. This scoping task addressed the issue of reproducibility for Saltstone.

  7. Decontamination solution development studies

    SciTech Connect

    Allen, R.P.; Fetrow, L.K.; Kjarmo, H.E.; Pool, K.H.

    1993-09-01

    This study was conducted for the Westinghouse Hanford Company (WHC) by Pacific Northwest Laboratory (PNL) as part of the Hanford Grout Technology Program (HGTP). The objective of this study was to identify decontamination solutions capable of removing radioactive contaminants and grout from the Grout Treatment Facility (GTF) process equipment and to determine the impact of these solutions on equipment components and disposal options. The reference grout used in this study was prepared with simulated double-shell slurry feed (DSSF) and a dry blend consisting of 40 wt % limestone flour, 28 wt % blast furnace slag, 28 wt % fly ash, and 4 wt % type I/II Portland cement.

  8. Operator Certification Study Guide.

    ERIC Educational Resources Information Center

    American Water Works Association, Denver, CO.

    This study guide contains typical questions and answers that all levels of water treatment plant operators might expect to find on a certification examination. The manual covers the basic sciences, treatment techniques, testing procedures, and federal legislation. (Author/SB)

  9. The Study of Matter.

    ERIC Educational Resources Information Center

    Campbell, Peter

    2000-01-01

    Reviews the booklet "The Study of Matter" produced by the Institute of Physics as part of their Shaping the Future series. This booklet is designed for teachers of chemistry, physics, design and technology, and biology. (Author/CCM)

  10. Kuwait oil spill studied

    NASA Astrophysics Data System (ADS)

    Bush, Susan

    1992-02-01

    More than a year after the Persian Gulf War, scientists are still trying to assess the environmental impact of the estimated 6-8 million barrels of oil that were dumped into the gulf and to understand the environmental processes that take place in such a disturbance. Many atmospheric studies were done in the months immediately following the war, but oceanographic studies have been slower in getting started.The National Oceanic and Atmospheric Administration is currently spearheading a major oceanographic study being undertaken in the Persian Gulf by the research vessel Mt. Mitchell. The ship left its home port of Norfolk, Va., in mid-January and arrived in Muscat, Oman, on February 16 to begin a 100-day oceanographic and environmental survey. The six-leg cruise will feature physical oceanography, near-shore, and marine life studies.

  11. Wilson Cycle studies

    NASA Technical Reports Server (NTRS)

    Burke, Kevin

    1987-01-01

    Regional lineaments in continental evolution were studied. It was concluded that lineaments within continents are attributed to a small number of processes of continent formation and modification, but interactions among these processes may produce complex patterns.

  12. IRD dropout study

    NASA Technical Reports Server (NTRS)

    Yalowitz, Jeffrey S.; Schroer, Michael A.; Dickson, John E., Jr.

    1992-01-01

    This final report describes work performed by SRS Technologies for the NASA Marshall Space Flight Center under Contract NAS8-39077, entitled 'Integrated Receiver-Decoder Dropout Study'. The purpose of the study was to determine causes of signal fading effects on ultra-high-frequency (UHF) range safety transmissions to the Space Shuttle during flyout. Of particular interest were deep fades observed at the External Tank (ET) Integrated Receiver-Decoder (IRD) during the flyout interval between solid rocket booster separation and ET separation. Analytical and simulation methods were employed in this study to assess observations captured in flight telemetry data records. Conclusions based on the study are presented in this report, and recommendations are given for future experimental validation of the results.

  13. Geysers reservoir studies

    SciTech Connect

    Bodvarsson, G.S.; Lippmann, M.J.; Pruess, K. )

    1993-01-01

    Lawrence Berkeley Laboratory is conducting several research projects related to issues of interest to The Geysers operators, including those that deal with understanding the nature of vapor-dominated systems, measuring or inferring reservoir processes and parameters, and studying the effects of liquid injection. All of these topics are directly or indirectly relevant to the development of reservoir strategies aimed at stabilizing or increasing production rates of non-corrosive steam, low in non-condensable gases. Three reservoir engineering studies are described in some detail, that is: (a) Modeling studies of heat transfer and phase distribution in two-phase geothermal reservoirs; (b) Numerical modeling studies of Geysers injection experiments; and (c) Development of a dual-porosity model to calculate mass flow between rock matrix blocks and neighboring fractures.

  14. HYDROGEOLOGIC CASE STUDIES

    EPA Science Inventory

    Hydrogeology is the foundation of subsurface site characterization for evaluations of monitored natural attenuation (MNA). Three case studies are presented. Examples of the potentially detrimental effects of drilling additives on ground-water samples from monitoring wells are d...

  15. Studies in Aeolian geology

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1988-01-01

    The objective of the research was to assess the significance of aeolian (windblown) processes in the evolution of planetary surfaces. The approach was to use wind tunnel simulations, field studies of possible analogs, and analyses of spacecraft data.

  16. Comparative Packaging Study

    NASA Technical Reports Server (NTRS)

    Perchonok, Michele; Antonini, David

    2008-01-01

    This viewgraph presentation describes a comparative packaging study for use on long duration space missions. The topics include: 1) Purpose; 2) Deliverables; 3) Food Sample Selection; 4) Experimental Design Matrix; 5) Permeation Rate Comparison; and 6) Packaging Material Information.

  17. Applied Research Study

    NASA Technical Reports Server (NTRS)

    Leach, Ronald J.

    1997-01-01

    The purpose of this project was to study the feasibility of reusing major components of a software system that had been used to control the operations of a spacecraft launched in the 1980s. The study was done in the context of a ground data processing system that was to be rehosted from a large mainframe to an inexpensive workstation. The study concluded that a systematic approach using inexpensive tools could aid in the reengineering process by identifying a set of certified reusable components. The study also developed procedures for determining duplicate versions of software, which were created because of inadequate naming conventions. Such procedures reduced reengineering costs by approximately 19.4 percent.

  18. Agricultural Health Study

    MedlinePlus

    ... North Carolina or Iowa. Participants classified as "private pesticide applicators" are farmers or nursery workers. The study also includes a small percentage of "commercial pesticide applicators" from Iowa who work for pest control ...

  19. Sturgeon study - specimens needed

    SciTech Connect

    Snyder, D.E.; Matthews, R.A.

    1983-01-01

    Preliminary results of a study to determine morphological criteria and verify those already suggested in the published literature for identifying the larvae of the Atlantic sturgeon and the endangered short nose sturgeon are presented. (ACR)

  20. What Are Sleep Studies?

    MedlinePlus

    ... August 19, 2014 Gary H. Gibbons Why Do Fruit Flies Take Naps? NHLBI Investigator Studies Connections Between Sleep Patterns and Gene Networks in Fruit Flies Read all Director's Messages Twitter Facebook YouTube Google+ ...

  1. Exploratory studies, 1988

    SciTech Connect

    Not Available

    1989-05-01

    This report discusses the following topics: accelerator physics for the ALS; SSC support; machine investigations; mathematical techniques in particle dynamics; APIARY: B-factory studies; and two-beam accelerators and bright electron sources.

  2. PPB | Study Team

    Cancer.gov

    The Pleuropulmonary Blastoma (PPB) DICER1 Syndrome Study team is made up of researchers from the National Cancer Institute, Children¹s National Medical Center, the International Pleuropulmonary Blastoma Registry, and Washington University in St. Louis.

  3. Tethered gravity laboratories study

    NASA Technical Reports Server (NTRS)

    Lucchetti, F.

    1989-01-01

    Variable Gravity Laboratory studies are discussed. The following subject areas are covered: (1) conceptual design and engineering analysis; (2) control strategies (fast crawling maneuvers, main perturbations and their effect upon the acceleration level); and (3) technology requirements.

  4. Sleep studies (image)

    MedlinePlus

    During a sleep study the sleep cycles and stages of sleep are monitored. Electrodes are placed to monitor continuous recordings of brain waves, electrical activity of muscles, eye movement, respiratory ...

  5. Septic Systems Case Studies

    EPA Pesticide Factsheets

    A collection of septic systems case studies to help community planners, elected officials, health department staff, state officials, and interested citizens explore alternatives for managing their decentralized wastewater treatment systems.

  6. Accelerator research studies

    SciTech Connect

    Not Available

    1992-01-01

    The Accelerator Research Studies program at the University of Maryland, sponsored by the Department of Energy under grant number DE-FG05-91ER40642, is currently in the first year of a three-year funding cycle. The program consists of the following three tasks: TASK A, Study of Transport and Longitudinal Compression of Intense, High-Brightness Beams, TASK B, Study of Collective Ion Acceleration by Intense Electron Beams and Pseudospark Produced High Brightness Electron Beams; TASK C, Study of a Gyroklystron High-power Microwave Source for Linear Colliders. In this report we document the progress that has been made during the past year for each of the three tasks.

  7. Nature Study Tips. Spiders.

    ERIC Educational Resources Information Center

    Mulaik, Stanley B.

    1990-01-01

    Different types of spiders, their ranges and habits are discussed. Activities associated with the study of spiders are suggested. Four references are listed which may be of interest to beginners. (CW)

  8. Building an Integrated Study

    ERIC Educational Resources Information Center

    Collins, Myrtle T.; Greenberg, Marvin

    1974-01-01

    Article described a plan to develop integrated study through music activities. Students learned to become more independent learners while concentrating on more complex and creative activities. (Author/RK)

  9. LANL Studies Earth's Magnetosphere

    ScienceCinema

    Daughton, Bill

    2016-07-12

    A new 3-D supercomputer model presents a new theory of how magnetic reconnection works in high-temperature plasmas. This Los Alamos National Laboratory research supports an upcoming NASA mission to study Earth's magnetosphere in greater detail than ever.

  10. Learn about Clinical Studies

    MedlinePlus

    ... is to make sure that the study is ethical and that the rights and welfare of participants ... trials provide the basis for the development and marketing of new drugs, biological products, and medical devices. ...

  11. MULTIPLE CONTAMINANTS CASE STUDIES

    EPA Science Inventory

    The presentation provides information taken from the arsenic demonstration program projects that have treatment systems removing multiply contaminants from drinking water. The case studies sited in the presentation consist of projects that have arsenic along with either nitrate, ...

  12. Putting the Study Together

    ERIC Educational Resources Information Center

    Child & Youth Services, 2007

    2007-01-01

    This chapter outlines the research design including the nature of the research strategy, tools, respondents, and theoretical and methodological concerns in a child and youth care qualitative study. (Contains 3 figures and 9 notes.)

  13. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Gill, J. C.; Earle, R. V.; Mar, H. M.

    1982-01-01

    The objective of the Rotorcraft Convertible Engine Study was to define future research and technology effort required for commercial development by 1988 of convertible fan/shaft gas turbine engines for unconventional rotorcraft transports. Two rotorcraft and their respective missions were defined: a Fold Tilt Rotor aircraft and an Advancing Blade Concept (ABC) rotorcraft. Sensitivity studies were conducted with these rotorcraft to determine parametrically the influence of propulsion characteristics on aircraft size, mission fuel requirements, and direct operating costs (DOC). The two rotorcraft were flown with conventional propulsion systems (separate lift/cruise engines) and with convertible propulsion systems to determine the benefits to be derived from convertible engines. Trade-off studies were conducted to determine the optimum engine cycle and staging arrangement for a convertible engine. Advanced technology options applicable to convertible engines were studied. Research and technology programs were identified which would ensure technology readiness for commercial development of convertible engines by 1988.

  14. Earth study from space

    NASA Technical Reports Server (NTRS)

    Sidorenko, A. V.

    1981-01-01

    The significance that space studies are making to all Earth sciences in the areas of geography, geodesy, cartography, geology, meteorology, oceanology, agronomy, and ecology is discussed. It is predicted that cosmonautics will result in a revolution in science and technology.

  15. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Ergun Kuru; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Gerald Kane; Len Volk; Mark Pickell; Evren Ozbayoglu; Barkim Demirdal; Paco Vieira; Affonso Lourenco

    1999-10-15

    This report includes a review of the progress made in ACTF Flow Loop development and research during 90 days pre-award period (May 15-July 14, 1999) and the following three months after the project approval date (July15-October 15, 1999) The report presents information on the following specific subjects; (a) Progress in Advanced Cuttings Transport Facility design and development, (b) Progress report on the research project ''Study of Flow of Synthetic Drilling Fluids Under Elevated Pressure and Temperature Conditions'', (c) Progress report on the research project ''Study of Cuttings Transport with Foam Under LPAT Conditions (Joint Project with TUDRP)'', (d) Progress report on the research project ''Study of Cuttings Transport with Aerated Muds Under LPAT Conditions (Joint Project with TUDRP)'', (e) Progress report on the research project ''Study of Foam Flow Behavior Under EPET Conditions'', (f) Progress report on the instrumentation tasks (Tasks 11 and 12) (g) Activities towards technology transfer and developing contacts with oil and service company members.

  16. A Study in Competition

    ERIC Educational Resources Information Center

    Payne, Therese Anne

    1973-01-01

    Describes a microbiological experiment designed to study the competition between two species of bacteria. Experimental procedures and data obtained in conducting this experiment are provided, together with a discussion of the results. (JR)

  17. Agricultural Health Study

    Cancer.gov

    A prospective cohort study of commercial pesticide applicators, farmers and farmers' spouses in Iowa and North Carolina conducted in collaboration between the NIH and the U.S. Evironmental Protection Agency

  18. LANL Studies Earth's Magnetosphere

    SciTech Connect

    Daughton, Bill

    2011-04-15

    A new 3-D supercomputer model presents a new theory of how magnetic reconnection works in high-temperature plasmas. This Los Alamos National Laboratory research supports an upcoming NASA mission to study Earth's magnetosphere in greater detail than ever.

  19. Schoolground Soil Studies.

    ERIC Educational Resources Information Center

    Doyle, Charles

    1978-01-01

    Outlined are simple activities for studying soil, which can be conducted in the schoolyard. Concepts include soil profiles, topsoil, soil sizes, making soil, erosion, slope, and water absorption. (SJL)

  20. Workshop I: Gender Studies

    NASA Astrophysics Data System (ADS)

    Hennessey, Eden; Kurup, Anitha; Meza-Montes, Lilia; Shastri, Prajval; Ghose, Shohini

    2015-12-01

    Participants in the Gender Studies workshop of the 5th IUPAP International Conference on Women in Physics discussed the gender question in science practice from a policy perspective, informed by investigations from the social science disciplines. The workshop's three sessions—"Equity and Education: Examining Gender Stigma in Science," "A Comparative Study of Women Scientists and Engineers: Experiences in India and the US," and "Toward Gender Equity Through Policy: Characterizing the Social Impact of Interventions—are summarized, and the resulting recommendations presented.

  1. Cholera studies*†

    PubMed Central

    Pollitzer, R.

    1955-01-01

    In this study, the author describes in detail experimental cholera infection of mammals (infection by the oral route, intragastric inoculation, and intestinal, gall-bladder, and parenteral infection). The pathogenicity for lower animals is examined, and certain observations on insects are included. The second part of the study is devoted to the pathology of human cholera (morbid anatomy distribution of the causative organisms in the dead bodies of cholera victims, and pathogenesis). PMID:13284569

  2. Concrete containment aging study

    SciTech Connect

    Pachner, J.; Tai, T.M.; Naus, D.

    1994-04-01

    In 1989, IAEA initiated a pilot study on the management of aging of nuclear power plant components. The Phase I and II studies of concrete containment are discussed. With the data base, plant owners will be able to review and enhance their existing programs. IAEA will analyze data provided by participating plants and the report is scheduled to be released by late 1994 (final report release mid-1995).

  3. Trajectory Code Studies, 1987

    SciTech Connect

    Poukey, J.W.

    1988-01-01

    The trajectory code TRAJ has been used extensively to study nonimmersed foilless electron diodes. The basic goal of the research is to design low-emittance injectors for electron linacs and propagation experiments. Systems studied during 1987 include Delphi, Recirc, and Troll. We also discuss a partly successful attempt to extend the same techniques to high currents (tens of kA). 7 refs., 30 figs.

  4. Tethered subsatellite study

    NASA Technical Reports Server (NTRS)

    Baker, W. P.; Dunkin, J. A.; Galaboff, Z. J.; Johnston, K. D.; Kissel, R. R.; Rheinfurth, M. H.; Siebel, M. P. L.

    1976-01-01

    The results are presented of studies performed relating to the feasibility of deploying a subsatellite from the shuttle by means of a tether. The dynamics, the control laws, the aerodynamics, the heating, and some communication considerations of the tethered subsatellite system are considered. Nothing was found that prohibits the use of a subsatellite joined to the shuttle by a long (100 km) tether. More detailed studies directed at specific applications are recommended.

  5. Power subsystem automation study

    NASA Technical Reports Server (NTRS)

    Tietz, J. C.; Sewy, D.; Pickering, C.; Sauers, R.

    1984-01-01

    The purpose of the phase 2 of the power subsystem automation study was to demonstrate the feasibility of using computer software to manage an aspect of the electrical power subsystem on a space station. The state of the art in expert systems software was investigated in this study. This effort resulted in the demonstration of prototype expert system software for managing one aspect of a simulated space station power subsystem.

  6. Radiation budget study

    NASA Astrophysics Data System (ADS)

    Hartmann, D. L.

    Scientific applications of satellite measurements of the radiative flux density at the top of the atmosphere are discussed in a general review and illustrated with diagrams, maps, and graphs. Topics examined include model development and verification, empirical studies of the global radiation budget, regional energy budgeting, interannual-variability studies, and seasonal and nonseasonal variations in ocean-land radiation budgets. The need for long-term homogeneous series of observations with good spatial and temporal resolution is stressed.

  7. Nanoindentation study of nanofibers

    NASA Astrophysics Data System (ADS)

    Tan, E. P. S.; Lim, C. T.

    2005-09-01

    Nanoindentation study of a single poly(L-lactic acid) nanofiber produced by the phase separation method was performed using an atomic force microscope (AFM) cantilever tip. Issues concerning the use of AFM for nanoindentation of polymer nanofibers were discussed. The Hertz theory of contact mechanics was used to analyze the indentation results. It was found that the elastic modulus was comparable to that obtained from the nanoscale three-point bend test done in our previous study, after roughness correction was made.

  8. Blood Preservation Study.

    DTIC Science & Technology

    1983-10-01

    stordge. Since dihydroxyacetone ( DHA ) seems a very promising additive for 2,3-DPG preservation, basic studies of metabolism of DHA were carried out. These...Washington,D.C. pp. 285-297. 16. Beutler, E. and Guinto, E. 1972. The metabolism of dihydroxyacetone ( DHA ) by human erythrocytes. Clinical Research...CPD with various additives such as ascorbic acid and dihydroxyacetone , and BAGPM mixing exerted a 2,3-DPG- sparing effect. The studies of the effect of

  9. Advanced planetary studies

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Results of planetary advanced studies and planning support provided by Science Applications, Inc. staff members to Earth and Planetary Exploration Division, OSSA/NASA, for the period 1 February 1981 to 30 April 1982 are summarized. The scope of analyses includes cost estimation, planetary missions performance, solar system exploration committee support, Mars program planning, Galilean satellite mission concepts, and advanced propulsion data base. The work covers 80 man-months of research. Study reports and related publications are included in a bibliography section.

  10. Studies in Battle Command

    DTIC Science & Technology

    1995-01-01

    Creek stronghold at Horseshoe Bend . Red Eagle and some 1,500 Creeks had fortified a peninsula there by erecting a substantial breastwork along its... Horseshoe Bend proved decisive. A proud but defeated Red Eagle surrendered himself to General Jackson in April, stating that “If I had an army, I 23...STUDIES IN BATTLE COMMAND By the Faculty Combat Studies Institute U.S. Army Command and General Staff ColIege Fort Leavenworth, Kansas IES

  11. Constellation Commodities Studies Summary

    NASA Technical Reports Server (NTRS)

    Dirschka, Eric

    2011-01-01

    Constellation program was NASA's long-term program for space exploration. The goal of the commodities studies was to solicit industry expertise in production, storage, and transportation required for future use and to improve efficiency and life cycle cost over legacy methods. Objectives were to consolidate KSC, CCAFS and other requirements; extract available industry expertise; identify commercial opportunities; and establish synergy with State of Florida partnerships. Study results are reviewed.

  12. Genome Wide Association Studies

    NASA Astrophysics Data System (ADS)

    Sebastiani, Paola; Solovieff, Nadia

    The availability of high throughput technology for parallel genotyping has opened the field of genetics to genome-wide association studies (GWAS). These studies generate massive amount of genetic data that challenge investigators with issues related to data management, statistical analysis of large data sets, visualization, and annotation of results. We will review the common approach to analysis of GWAS data and then discuss options to learn more from these data.

  13. PFBC system studies

    SciTech Connect

    Reed, M.E.

    1994-10-01

    System studies of PFBC systems are summarized in this paper. These studies include: thermal efficiency; NO{sub x} stochastic analysis; dynamic modeling; scoping studies; and hazardous air pollutant (HAP) studies. These studies are being used for various reasons: to validate the economic and environmental benefits that this technology offers the country, to identify issues associated with the commercialization of PFBC technology, and to help the DOE and its industrial partners focus on those RD&D activities which produce the biggest bang for the buck, an increasingly important goal in the present climate of increasingly tight Federal and corporate budgets. This year, the conclusion that NO{sub x} generation in the solids combustor is the most important factor in determining NO{sub x} production in an uncontrolled system was of particular significance. The initial assessment of HAP`s, showing a possible reduction in HAPs emissions if the barrier filter is operated below 600 C in a first-generation PFBC, was the first time this type of data was produced on the ability of PFBC systems to be a low HAP`s emission technology. Work will continue to improve these analytic tools used in these system studies useful for both DOE and its industrial partners.

  14. Networked Microgrids Scoping Study

    SciTech Connect

    Backhaus, Scott N.; Dobriansky, Larisa; Glover, Steve; Liu, Chen-Ching; Looney, Patrick; Mashayekh, Salman; Pratt, Annabelle; Schneider, Kevin; Stadler, Michael; Starke, Michael; Wang, Jianhui; Yue, Meng

    2016-12-05

    Much like individual microgrids, the range of opportunities and potential architectures of networked microgrids is very diverse. The goals of this scoping study are to provide an early assessment of research and development needs by examining the benefits of, risks created by, and risks to networked microgrids. At this time there are very few, if any, examples of deployed microgrid networks. In addition, there are very few tools to simulate or otherwise analyze the behavior of networked microgrids. In this setting, it is very difficult to evaluate networked microgrids systematically or quantitatively. At this early stage, this study is relying on inputs, estimations, and literature reviews by subject matter experts who are engaged in individual microgrid research and development projects, i.e., the authors of this study The initial step of the study gathered input about the potential opportunities provided by networked microgrids from these subject matter experts. These opportunities were divided between the subject matter experts for further review. Part 2 of this study is comprised of these reviews. Part 1 of this study is a summary of the benefits and risks identified in the reviews in Part 2 and synthesis of the research needs required to enable networked microgrids.

  15. Wilson Cycle studies

    NASA Technical Reports Server (NTRS)

    Burke, Kevin

    1987-01-01

    The main activity relating to the study during this half year was a three week field trip to study Chinese sedimentary basins (June 10 to July 3, 1986) at no cost to the project. This study, while of a reconnaissance character, permitted progress in understanding how the processes of island arc-collision and micro-continental collision operated during the Paleozoic in far western China (especially the Junggar and Tarim basins and in the intervening Tien Shan Mountains). These effects of the continuing collision of India and Asia on the area were also studied. Most specifically, these result in the elevation of the Tien Shan to more than 4 km above sea level and the depression of Turfan to move 150m below sea level. Both thrusting and large-scale strike-slip motion are important in producing these elevation changes. Some effort during the half year was also devoted to the study of greenstone-belts in terms of the Wilson Cycle.

  16. Cosmos-1989 immunology studies

    NASA Technical Reports Server (NTRS)

    Sonnenfeld, Gerald

    1991-01-01

    Evidence from both human and rodent studies has indicated that alterations in immunological parameters occur after space flight. The number of flight experiments has been small, and the full breadth of immunological alterations occurring after space flight remains to be established. Among the major effects on immune responses after space flight that have been reported are: alterations in lymphocyte blastogenesis and natural killer cell activity, alterations in production of cytokines, changes in leukocyte sub-population distribution, and decreases in the ability in the ability of bone marrow cells to respond to colony stimulating factors. Changes have been reported in immunological parameters of both humans and rodents. The significance of these alterations in relation to resistance to infection remains to be established. The current study involved a determination of the effects of flight on Cosmos mission 2044 on leukocyte subset distribution and the sensitivity of bone marrow cells to colony stimulating factor-GM. A parallel study with antiorthostatic suspension was also carried out. The study involved repetition and expansion of studies carried out on Cosmos 1887.

  17. Photovoltaics information user study

    SciTech Connect

    Belew, W.W.; Wood, B.L.; Marie, T.L.; Reinhardt, C.L.

    1980-10-01

    The results of a series of telephone interviews with groups of users of information on photovoltaics (PV) are described. These results, part of a larger study on many different solar technologies, identify types of information each group needed and the best ways to get information to each group. The report is 1 of 10 discussing study results. The overall study provides baseline data about information needs in the solar community. It covers these technological areas: photovoltaics, passive solar heating and cooling, active solar heating and cooling, biomass energy, solar thermal electric power, solar industrial and agricultural process heat, wind energy, ocean energy, and advanced energy storage. An earlier study identified the information user groups in the solar community and the priority (to accelerate solar energy commercialization) of getting information to each group. In the current study only high-priority groups were examined. Results from seven PV groups respondents are analyzed in this report: DOE-Funded Researchers, Non-DOE-Funded Researchers, Researchers Working for Manufacturers, Representatives of Other Manufacturers, Representatives of Utilities, Electric Power Engineers, and Educators.

  18. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Gerald Kane; Mark Pickell; Len Volk; Mike Volk; Barkim Demirdal; Affonso Lourenco; Evren Ozbayoglu; Paco Vieira; Lei Zhou

    2000-01-30

    This is the second quarterly progress report for Year 2 of the ACTS project. It includes a review of progress made in Flow Loop development and research during the period of time between Oct 1, 2000 and December 31, 2000. This report presents a review of progress on the following specific tasks: (a) Design and development of an Advanced Cuttings Transport Facility (Task 2: Addition of a foam generation and breaker system), (b) Research project (Task 6): ''Study of Cuttings Transport with Foam Under LPAT Conditions (Joint Project with TUDRP)'', (c) Research project (Task 7): ''Study of Cuttings Transport with Aerated Muds Under LPAT Conditions (Joint Project with TUDRP)'', (d) Research project (Task 8): ''Study of Flow of Synthetic Drilling Fluids Under Elevated Pressure and Temperature Conditions'', (e) Research project (Task 9): ''Study of Foam Flow Behavior Under EPET Conditions'', (f) Research project (Task 10): ''Study of Cuttings Transport with Aerated Mud Under Elevated Pressure and Temperature Conditions'', (g) Research on instrumentation tasks to measure: Cuttings concentration and distribution in a flowing slurry (Task 11), and Foam properties while transporting cuttings. (Task 12), (h) Development of a Safety program for the ACTS Flow Loop. Progress on a comprehensive safety review of all flow-loop components and operational procedures. (Task 1S). (i) Activities towards technology transfer and developing contacts with Petroleum and service company members, and increasing the number of JIP members. The tasks Completed During This Quarter are Task 7 and Task 8.

  19. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Gerald Kane; Mark Pickell; Len Volk; Mike Volk; Barkim Demirdal; Affonso Lourenco; Evren Ozbayoglu; Paco Vieira

    2000-10-30

    This is the first quarterly progress report for Year 2 of the ACTS project. It includes a review of progress made in Flow Loop development and research during the period of time between July 14, 2000 and September 30, 2000. This report presents information on the following specific tasks: (a) Progress in Advanced Cuttings Transport Facility design and development (Task 2), (b) Progress on research project (Task 8): ''Study of Flow of Synthetic Drilling Fluids Under Elevated Pressure and Temperature Conditions'', (c) Progress on research project (Task 6): ''Study of Cuttings Transport with Foam Under LPAT Conditions (Joint Project with TUDRP)'', (d) Progress on research project (Task 7): ''Study of Cuttings Transport with Aerated Muds Under LPAT Conditions (Joint Project with TUDRP)'', (e) Progress on research project (Task 9): ''Study of Foam Flow Behavior Under EPET Conditions'', (f) Initiate research on project (Task 10): ''Study of Cuttings Transport with Aerated Mud Under Elevated Pressure and Temperature Conditions'', (g) Progress on instrumentation tasks to measure: Cuttings concentration and distribution (Tasks 11), and Foam properties (Task 12), (h) Initiate a comprehensive safety review of all flow-loop components and operational procedures. Since the previous Task 1 has been completed, we will now designate this new task as: (Task 1S). (i) Activities towards technology transfer and developing contacts with Petroleum and service company members, and increasing the number of JIP members.

  20. Pilot Field Test Study

    NASA Technical Reports Server (NTRS)

    Sherriff, Abigail

    2015-01-01

    The Field Test study is currently in full swing, preceded by the successful completion of the Pilot Field Test study that paved the way for collecting data on the astronauts in the medical tent in Kazakhstan. Abigail Sherriff worked alongside Logan Dobbe on one Field Test aspect to determine foot clearance over obstacles (5cm, 10cm, and 15cm) using APDM Inc. Internal Measurement Units (IMU) worn by the astronauts. They created a program to accurately calculate foot clearance using the accelerometer, magnetometer, and gyroscope data with the IMUs attached to the top of the shoes. To validate the functionality of their program, they completed a successful study on test subjects performing various tasks in an optical motion studio, considered a gold standard in biomechanics research. Future work will include further validation and expanding the program to include other analyses.

  1. Ventilation technologies scoping study

    SciTech Connect

    Walker, Iain S.; Sherman, Max H.

    2003-09-30

    This document presents the findings of a scoping study commissioned by the Public Interest Energy Research (PIER) program of the California Energy Commission to determine what research is necessary to develop new residential ventilation requirements for California. This study is one of three companion efforts needed to complete the job of determining the needs of California, determining residential ventilation requirements, and determining appropriate ventilation technologies to meet these needs and requirements in an energy efficient manner. Rather than providing research results, this scoping study identifies important research questions along with the level of effort necessary to address these questions and the costs, risks, and benefits of pursuing alternative research questions. In approaching these questions and level of effort, feasibility and timing were important considerations. The Commission has specified Summer 2005 as the latest date for completing this research in time to update the 2008 version of California's Energy Code (Title 24).

  2. Iron studies in hemophilia

    SciTech Connect

    Lottenberg, R.; Kitchens, C.S.; Roessler, G.S.; Noyes, W.D.

    1981-12-01

    Although iron deficiency is not recognized as a usual complication of hemophilia, we questioned whether intermittent occult loss of blood in urine or stool might predispose hemophiliacs to chronic iron deficiency. Seven men with factor VII and one with factor IX deficiency were studied. Blood studied, bone marrow aspirates, urine and stool samples, and ferrokinetics with total-body counting up to five months were examined. These data showed no excessive loss of blood during the study period; however, marrow iron stores were decidedly decreased, being absent in four subjects. We suggest that in some hemophiliacs, iron deposits in tissues such as synovial membranes may form a high proportion of the body's total iron stores.

  3. Techniques for carcinogenicity studies.

    PubMed

    Weisburger, E K

    1981-09-01

    Short-term tests to detect genetic, chromosomal, or DNA damage are now required by regulatory agencies for any new compound proposed for commercial production. Furthermore, full-scale carcinogenicity tests may be required for certain compounds. In this circumstance, the compound-related factors including stability, purity, physical properties, and chemical structure and reactivity must be considered. Animal factors include species and strain of test animal, route of administration, age, sex, diet, and spontaneous tumor incidence. A team of qualified investigators with experience in various disciplines is required to conduct the studies properly. Quality control measures and adherence to the code of good laboratory practice are also necessary during all phases of the study. The investment in a carcinogenicity study therefore becomes fairly substantial in terms of both time and money.

  4. Cosmos: 1989 immunology studies

    NASA Technical Reports Server (NTRS)

    Sonnenfeld, Gerald

    1991-01-01

    The effects of flight on Cosmos mission 2044 on leukocyte subset distribution and the sensitivity of bone marrow cells to colony stimulating factor-GM were determined. A parallel study with antiorthostatic suspension was also carried out. The study involved repetition and expansion of studies performed on Cosmos 1887. Spleen and bone marrow cells were obtained from flown, vivarium control, synchronous control, and suspended rats. The cells were stained with a series of monoclonal antibodies directed against rat leukocyte cell surface antigens. Control cells were stained with a monoclonal antibody directed against an irrelevant species or were unstained. Cells were then analyzed for fluorescence using a FACSCAN flow cytometer. Bone marrow cells were placed in culture with GM-CSF in McCoy's 5a medium and incubated for 5 days. Cultures were then evaluated for the number of colonies of 50 cells or greater.

  5. Current Automotive Holometry Studies

    NASA Astrophysics Data System (ADS)

    Marchi, Mitchell M.; Snyder, D. S.

    1990-04-01

    Holometry studies of automotive body and powertrain components have become a very useful high resolution test methodology to knowledgeable Ford engineering personnel. Current examples of studies that represent the static or dynamic operational conditions of the automotive test component are presented. Continuous wave laser holometry, computer aided holometry (CAH) and pulsed laser holometry were the holometric techniques used to study the following subjects: (1) body in prime (BIP) vibration modes, (2) transmission flexplate stud-torque converter deformation due to engine torque pulses, (3) engine cylinder head and camshaft support structure deformation due to cylinder pressure and (4) engine connecting rod/cap lift-off. Static and dynamic component loading and laboratory techniques required to produce usable and valid test results are discussed along with possible conclusions for the engineering concerns.

  6. Critical Density Interaction Studies

    SciTech Connect

    Young, P; Baldis, H A; Cheung, P; Rozmus, W; Kruer, W; Wilks, S; Crowley, S; Mori, W; Hansen, C

    2001-02-14

    Experiments have been performed to study the propagation of intense laser pulses to high plasma densities. The issue of self-focusing and filamentation of the laser pulse as well as developing predictive capability of absorption processes and x-ray conversion efficiencies is important for numerous programs at the Laboratory, particularly Laser Program (Fast Ignitor and direct-drive ICF) and D&NT (radiography, high energy backlighters and laser cutting). Processes such as resonance absorption, profile modification, linear mode conversion, filamentation and stimulated Brillouin scattering can occur near the critical density and can have important effects on the coupling of laser light to solid targets. A combination of experiments have been used to study the propagation of laser light to high plasma densities and the interaction physics of intense laser pulses with solid targets. Nonparaxial fluid codes to study nonstationary behavior of filamentation and stimulated Brillouin scattering at high densities have also been developed as part of this project.

  7. Toxicological study of benzotrifuroxan

    SciTech Connect

    London, J.E.; Smith, D.M.

    1983-04-01

    The calculated acute oral LD/sub 50//sup 30/ (lethal dose for 50% of the animals occurring within 30 days after compound administration) value for Benzotrifuroxan (BTF) was 2884 mg/kg body weight in rats. The acute oral LD/sub 50//sup 30/ value in mice was greater than 5 g/kg. According to classical guidelines, this compound would be considered slightly toxic in both species. Skin application studies in the rabbit demonstrated the compound to be mildly irritating. The eye irritation study demonstrated BTF to be highly irritant when in contact with the eye, even to the point of causing corneal opacification and blindness. The sensitization study in the guinea pig did not show BTF to be deleterious in this regard.

  8. Black Hills hydrology study

    USGS Publications Warehouse

    Driscoll, D.G.

    1994-01-01

    The Black Hills area of western South Dakota is a valuable resource center. The area has attracted numerous residents and industries because of the availability of mineral, timber, agricultural, recreational, and water resources. The water resources of the area have been stressed locally by increasing population, periodic drought, and development of other resources. In response to residents' concerns about these stresses on the water resources, the Black Hills Hydrology Study was initiated in 1990 as a cooperative effort among the U.S. Geological Survey, the South Dakota Department of Environment and Natural Resources, and the West Dakota Water Development District. West Dakota represents the various local and county cooperators. This report describes the purpose, scope, approach, and status of the study and presents highlights from the first project data report produced for the study.

  9. Parylene C Aging Studies.

    SciTech Connect

    Achyuthan, Komandoor; Sawyer, Patricia Sue.; Mata, Guillermo Adrian; White II, Gregory Von; Bernstein, Robert

    2014-09-01

    Parylene C is used in a device because of its conformable deposition and other advantages. Techniques to study Parylene C aging were developed, and "lessons learned" that could be utilized for future studies are the result of this initial study. Differential Scanning Calorimetry yielded temperature ranges for Parylene C aging as well as post-deposition treatment. Post-deposition techniques are suggested to improve Parylene C performance. Sample preparation was critical to aging regimen. Short-term (%7E40 days) aging experiments with free standing and ceramic-supported Parylene C films highlighted "lessons learned" which stressed further investigations in order to refine sample preparation (film thickness, single sided uniform coating, machine versus laser cutting, annealing time, temperature) and testing issues ("necking") for robust accelerated aging of Parylene C.

  10. Oxidizer Scoping Studies

    SciTech Connect

    Chancellor, Christopher John

    2016-11-07

    The purpose of this report is to present the results of the acceptable knowledge (AK) review of oxidizers present in active waste streams, provide a technical analysis of the oxidizers, and report the results of the scoping study testing. This report will determine the fastest burning oxidizer to be used in the development of a Test Plan for Preparation and Testing of Sorbents Mixed with Oxidizer found in Transuranic Waste (DWT-TP-001). The companion report, DWT-RPT-002, Sorbent Scoping Studies, contains similar information for sorbents identified during the AK review of TRU waste streams. The results of the oxidizer and sorbent scoping studies will be used to inform the QL1 test plan. The QL1 test results will support the development of a basis of knowledge document that will evaluate oxidizing chemicals and sorbents in TRU waste and provide guidance for treatment.

  11. Seal design alternatives study

    SciTech Connect

    Van Sambeek, L.L.

    1993-06-01

    This report presents the results from a study of various sealing alternatives for the WIPP sealing system. Overall, the sealing system has the purpose of reducing to the extent possible the potential for fluids (either gas or liquid) from entering or leaving the repository. The sealing system is divided into three subsystems: drift and panel seals within the repository horizon, shaft seals in each of the four shafts, and borehole seals. Alternatives to the baseline configuration for the WIPP seal system design included evaluating different geometries and schedules for seal component installations and the use of different materials for seal components. Order-of-magnitude costs for the various alternatives were prepared as part of the study. Firm recommendations are not presented, but the advantages and disadvantages of the alternatives are discussed. Technical information deficiencies are identified and studies are outlined which can provide required information.

  12. Optimal symmetric flight studies

    NASA Technical Reports Server (NTRS)

    Weston, A. R.; Menon, P. K. A.; Bilimoria, K. D.; Cliff, E. M.; Kelley, H. J.

    1985-01-01

    Several topics in optimal symmetric flight of airbreathing vehicles are examined. In one study, an approximation scheme designed for onboard real-time energy management of climb-dash is developed and calculations for a high-performance aircraft presented. In another, a vehicle model intermediate in complexity between energy and point-mass models is explored and some quirks in optimal flight characteristics peculiar to the model uncovered. In yet another study, energy-modelling procedures are re-examined with a view to stretching the range of validity of zeroth-order approximation by special choice of state variables. In a final study, time-fuel tradeoffs in cruise-dash are examined for the consequences of nonconvexities appearing in the classical steady cruise-dash model. Two appendices provide retrospective looks at two early publications on energy modelling and related optimal control theory.

  13. LAWS hurricane studies

    NASA Technical Reports Server (NTRS)

    Molinari, John

    1995-01-01

    The Laser Atmospheric Wind Sounder (LAWS) has recently been deselected from the Earth Observing System (EOS). A broad range of orbital altitudes and laser power are being considered for future wind lidar missions. As a result, as was anticipated in the proposed work, it may be impossible to meaningfully study tropical cyclones with lidar wind data because data coverage (i.e., swath width) is insufficient. Research on this grant has focused on how to maximize the benefits of a wind lidar regardless of the choice of platform or laser. Our studies have shown that major unsolved problems in tropical meteorology relate to the structure, dynamics, and role in tropical cyclogenesis of 'easterly waves'. These disturbances exist almost everywhere in the global subtropics. Results are described that focus upon easterly wave impacts on eastern Pacific tropical cyclogenesis. The availability of wind lidar data would create tremendous opportunities for the study of these waves and their role in the general circulation.

  14. Cryogenic Propellant Densification Study

    NASA Technical Reports Server (NTRS)

    Ewart, R. O.; Dergance, R. H.

    1978-01-01

    Ground and vehicle system requirements are evaluated for the use of densified cryogenic propellants in advanced space transportation systems. Propellants studied were slush and triple point liquid hydrogen, triple point liquid oxygen, and slush and triple point liquid methane. Areas of study included propellant production, storage, transfer, vehicle loading and system requirements definition. A savings of approximately 8.2 x 100,000 Kg can be achieved in single stage to orbit gross liftoff weight for a payload of 29,484 Kg by utilizing densified cryogens in place of normal boiling point propellants.

  15. Hybrid receiver study

    NASA Technical Reports Server (NTRS)

    Stone, M. S.; Mcadam, P. L.; Saunders, O. W.

    1977-01-01

    The results are presented of a 4 month study to design a hybrid analog/digital receiver for outer planet mission probe communication links. The scope of this study includes functional design of the receiver; comparisons between analog and digital processing; hardware tradeoffs for key components including frequency generators, A/D converters, and digital processors; development and simulation of the processing algorithms for acquisition, tracking, and demodulation; and detailed design of the receiver in order to determine its size, weight, power, reliability, and radiation hardness. In addition, an evaluation was made of the receiver's capabilities to perform accurate measurement of signal strength and frequency for radio science missions.

  16. Studies in neuroendocrine pharmacology

    NASA Technical Reports Server (NTRS)

    Maickel, R. P.

    1976-01-01

    The expertise and facilities available within the Medical Sciences Program section on Pharmacology were used along with informational input from various NASA sources to study areas relevant to the manned space effort. Topics discussed include effects of drugs on deprivation-induced fluid consumption, brain biogenic amines, biochemical responses to stressful stimuli, biochemical and behavioral pharmacology of amphetamines, biochemical and pharmacological studies of analogues to biologically active indole compounds, chemical pharmacology: drug metabolism and disposition, toxicology, and chemical methodology. Appendices include a bibliography, and papers submitted for publication or already published.

  17. Photothermal degradation studies

    NASA Technical Reports Server (NTRS)

    Liang, R. H.

    1985-01-01

    Key reaction intermediates of photooxidation identified and characterized by laser flash Electron Spin Resonance (ESR) spectroscopy were discussed. Effects of temperature and ultraviolet intensity were studied in order to develop meaningful accelerated testing procedures for encapsulant evaluation. In a program to study the failure of Tedlar/ethylene vinyl acetate (EVA)/stainless steel modules, failure modes similar to those observed outdoors in real-time conditions were simulated in accelerated testing. An experimental technique was developed to quantitatively assess the extent of degradation.

  18. Electric Propulsion Study

    DTIC Science & Technology

    1990-08-01

    DTIC FILE COPY AL-TR-89-040 AD: AD-A227 121 Final Report forteprod Electric Propulsion Study 21 Sep 1988 to 30 Nov 1989 DTIC ’ELECTE0OCT 0c 41990u... Electric Propulsion Study (U) 12. PERSONAL AUTHOR(S) Cravens, Dennis J. 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Month, Day) 15. PAGE...identif bv block number) FIELD GROUP SUB-GROUP Inductive theories, electric propulsion, unified field 21 0- theories, Conservatc!±,n Laws, Dynamic

  19. Fathead fecundity study

    SciTech Connect

    Barman, M.A.E.; Geis, S.; Repavich, W.; Schappe, K.

    1995-12-31

    Fathead minnows (Pimephales promelas) are cultured in controlled laboratory settings for use in aquatic toxicity testing. Culturing is done to maintain a continuous supply of organisms of all ages; breeders, juveniles and larvae. This study is designed to determine the age at which peak egg production occurs. Fish are paired, one male to one female, at three to four months of age. Daily egg production is recorded and graphed. The graph of egg production vs. fish age will determine the age at which peak egg production occurs. The results of this study will provide information for more efficient use of lab space and staff, while maximizing egg production.

  20. Howitzer Technology Assessment Study.

    DTIC Science & Technology

    1980-11-01

    AD-A091 782 VEDA INC SOUTHAMPTON PA p~1t HOWITZER TECHNOLOGY ASSESSMENT STUDY.CU) Fs1/ NOV 80 A J CURRAN , J M MAGINN N000OI8?gC-0925 UNCLASSIFIED...ADIO SCONTRACTOR REPORT ARLCD-CR-SO036 0 HOWITZER TECHNOLOGY ASSESSMENT STUDY ROGER I. CURRAN - JAMES M. MAGINN VEDA INCORPORATED 1360 INDUSTRIAL...C-0925," 9. PERFORMING ORGANIZATION NAME ARC ADDRESS VI POGAMEUNTPRJCAS JPROe &. M HaSN. RJETTn Veda Incorporated 1360 Industrial Highway Southampton

  1. Home-Study Microlabs

    NASA Astrophysics Data System (ADS)

    Kennepohl, Dietmar

    1996-10-01

    This article presents the use of microscaled chemistry experiments for individual home study and how it can be incorporated into a course with traditional laboratory work. A portable home kit containing four experiments that can be carried out unsupervised by a distance education student in first-year university chemistry is described. Experiments include the physical chemistry of solutions, reactions and identification of aqueous cations, calorimetry, and quantitative determination of phosphorus. The results of a student survey of this home-study microlab kit are also presented and discussed.

  2. Spectrophotometric study of asteroids

    NASA Technical Reports Server (NTRS)

    Chapman, C. R.

    1974-01-01

    Observations of particular faint asteroids of interest, in particular the Trojans, were carried out during an observation run at Kitt Peak National Observatory (1.3 meter telescope) in September 1973, and an attempt was made to study the compositional variation within Hirayama families. A particularly important study was initiated to observe spectrophotometrically certain asteroids which are considered as potential source bodies for meteorites. A program was also undertaken to coordinate the spectrophotometry program with polarimetric and thermal-infrared observation programs being conducted elsewhere.

  3. Exploration case studies

    NASA Astrophysics Data System (ADS)

    Underwood, Jimmy M.

    1989-04-01

    NASA's Office of Exploration has undertaken four case studies for prospective expansion of manned space activities beyond earth orbit. The subjects of these studies are (1) an expedition to the Martian moon Phobos; (2) a three-mission expedition to Mars; (3) the construction of a man-tended lunar observatory; and (4) the construction of a lunar outpost to serve as the basis for construction of a Martian outpost. The fourth alternative would follow the recommendation of the National Commission on Space for the creation of a 'bridge between worlds' in which explorers would develop ways in which to 'live off the land' in a space environment.

  4. Advanced engine study program

    NASA Technical Reports Server (NTRS)

    Masters, A. I.; Galler, D. E.; Denman, T. F.; Shied, R. A.; Black, J. R.; Fierstein, A. R.; Clark, G. L.; Branstrom, B. R.

    1993-01-01

    A design and analysis study was conducted to provide advanced engine descriptions and parametric data for space transfer vehicles. The study was based on an advanced oxygen/hydrogen engine in the 7,500 to 50,000 lbf thrust range. Emphasis was placed on defining requirements for high-performance engines capable of achieving reliable and versatile operation in a space environment. Four variations on the expander cycle were compared, and the advantages and disadvantages of each were assessed. Parametric weight, envelope, and performance data were generated over a range of 7,500 to 50,000 lb thrust and a wide range of chamber pressure and nozzle expansion ratio.

  5. Fluorescence study of sugars

    NASA Astrophysics Data System (ADS)

    Thongjamroon, Sunida; Pattanaporkratana, Apichart

    2015-07-01

    We studied photoemission of monosaccharides and disaccharides using laser-induced fluorescence spectroscopy. A 532- nm, 10 mW, laser was used to excite the samples and back-scattering signals were collected by a spectrometer. We found that most sugars show weak fluorescence in solid phase but do not fluoresce when dissolved in water solutions. The emission spectra show similar peak intensity at 590 nm, but they are different in emission intensities. We suggest that the fluorescence spectra may be used to differentiate sugar type, even though the origin of the fluorescence is unclear and needed further study.

  6. Radionuclide studies in impotence

    SciTech Connect

    Hilson, A.J.; Lewis, C.A. )

    1991-04-01

    Impotence may be of physiological origin with causes including vascular or neurological pathology. Alternatively, it may be of psychogenic origin. Clinicians can distinguish between psychological and organic impotence by observing nocturnal penile tumescence. Non-radionuclide investigations for organic impotence include penile plethysmography or pulse Doppler analysis for arterial supply, cavernosometry for venous drainage, and biothesiometry or evoked potentials for neurological pathology. Radionuclide studies are primarily based on the use of technetium 99m-pertechnetate, 99mTc-red blood cells, or xenon 133 to study the blood flow, with or without pharmacological intervention, commonly papaverine. 26 references.

  7. Amtrak fuel consumption study

    SciTech Connect

    Hitz, J.

    1981-02-01

    This report documents a study of fuel consumption on National Railroad Passenger Corporation (Amtrak) trains and is part of an effort to determine effective ways of conserving fuel on the Amtrak system. The study was performed by the Transportation Systems Center (TSC). A series of 26 test runs were conducted on Amtrak trains operating between Boston, Massachusetts, and New Haven, Connecticut, to measure fuel consumption, trip time and other fuel-use-related parameters. The test data were analyzed and compared with results of the TSC Train Performance Simulator replicating the same operations.

  8. National Facilities study

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This study provides a set of recommendations for improving the effectiveness of our nation's aeronautics and space facilities. The study plan considers current and future government and commercial needs as well as DOD and NASA mission requirements through the year 2023. It addresses shortfalls in existing capabilities, new facility requirements, upgrades, consolidations, and phase-out of existing facilities. If the recommendations are implemented, they will provide world-class capability where it is vital to our country's needs and make us more efficient in meeting future needs.

  9. Plants Study Guide.

    ERIC Educational Resources Information Center

    Brynildson, Inga

    This study quide is intended to provide students with information about the types and functions of plants, along with some individual learning activities. The guide contains sections about: (1) the contributions of plants to life on earth and the benefits they afford to humanity; (2) the processes of photosynthesis and respiration; (3) the flow of…

  10. Cholera studies*†

    PubMed Central

    Pollitzer, R.

    1955-01-01

    The morphological characteristics, biochemical properties, and cultural characteristics of V. cholerae are described in great detail in this study. The author also discusses the resistance of the organism to temperature, humidity, sunlight, and various chemicals, as well as the viability of V. cholerae outside the body (in faeces, contaminated material, food, beverages, water, etc.). PMID:14379012

  11. Study Mode Negotiation.

    ERIC Educational Resources Information Center

    Vasan, Mani Le; Sargunan, Rajeswary

    This paper outlines a model of study mode negotiation between clients and English Language Training providers that has been developed at the University of Malaya, specifically related to English language writing skills as taught to corporate clients. Negotiation is used to reach decisions concerning the goals and methodology of learning to ensure…

  12. Applied Music (Individual Study).

    ERIC Educational Resources Information Center

    Texas Education Agency, Austin.

    Background information and resources to help students in grades 9-12 in Texas pursue an individual study contract in applied music is presented. To fulfill a contract students must publicly perform from memory, with accompaniment as specified, three selections from a list of approved music for their chosen field (instrument or voice). Material…

  13. IMMUNOASSAY HUMAN EXPOSURE STUDIES

    EPA Science Inventory

    The Human Exposure Research Branch has developed several enzyme-linked immunosorbent assay (ELISA) methods to support human exposure assessment studies. Immunoassays to detect low levels (<10 ng/mL) of chlorpyrifos in food, track-in dirt and house dust have been applied to sam...

  14. Australian Film Studies.

    ERIC Educational Resources Information Center

    Breen, Myles P.

    Although Australia had a vigorous film industry in the silent film era, it was stifled in the 1930s when United States and British interests bought up the Australian distribution channels and closed down the indigenous industry. However, the industry and film study have undergone a renaissance since the advent of the Labor government in 1972,…

  15. Digital communications study

    NASA Technical Reports Server (NTRS)

    Boorstyn, R. R.

    1973-01-01

    Research is reported dealing with problems of digital data transmission and computer communications networks. The results of four individual studies are presented which include: (1) signal processing with finite state machines, (2) signal parameter estimation from discrete-time observations, (3) digital filtering for radar signal processing applications, and (4) multiple server queues where all servers are not identical.

  16. Studying Ancient History.

    ERIC Educational Resources Information Center

    Barrow, Robin

    1982-01-01

    Defends the value and relevance of the study of ancient history and classics in history curricula. The unique homogeneity of the classical period contributes to its instructional manageability. A year-long, secondary-level course on fifth-century Greece and Rome is described to illustrate effective approaches to teaching ancient history. (AM)

  17. Social Studies: Grade 8.

    ERIC Educational Resources Information Center

    Manitoba Dept. of Education, Winnipeg.

    This Manitoba (Canada) curriculum guide for eighth grade social studies students contains suggested teaching strategies and learning activities in four units covering: (1) life during prehistoric and early historic times; (2) ancient civilizations; (3) life in early modern Europe; and (4) life in the modern world. Each unit includes an overview,…

  18. Reinventing Social Studies

    ERIC Educational Resources Information Center

    St. Jarre, Kevin

    2008-01-01

    There is so much more to preparing a citizen than merely running students like lemmings through a three-year succession of history survey courses. Everyone is neglecting most of the social sciences in American high schools today, favoring the sequential and systematic delivery of history. What should be primary in the teaching of social studies,…

  19. The Study of Education.

    ERIC Educational Resources Information Center

    Levit, Martin

    This paper examines several approaches to the study of the foundations of education and rejects all of them. Approaches are classified as "system-adaptive" or "system-reform" according to whether they examine existing educational systems and objectively analyze alternatives or whether they advocate specific new values or, indeed, freedom from all…

  20. Case Studies in Biology.

    ERIC Educational Resources Information Center

    Zeakes, Samuel J.

    1989-01-01

    A case study writing exercise used in a course on parasitology was found to be a powerful learning experience for students because it involved discipline-based technical writing and terminology, brought the students in as evaluators, applied current learning, caused interaction among all students, and simulated real professional activities. (MSE)