Contrast-enhanced endoscopic ultrasonography in digestive diseases.

PubMed

Hirooka, Yoshiki; Itoh, Akihiro; Kawashima, Hiroki; Ohno, Eizaburo; Itoh, Yuya; Nakamura, Yosuke; Hiramatsu, Takeshi; Sugimoto, Hiroyuki; Sumi, Hajime; Hayashi, Daijiro; Ohmiya, Naoki; Miyahara, Ryoji; Nakamura, Masanao; Funasaka, Kohei; Ishigami, Masatoshi; Katano, Yoshiaki; Goto, Hidemi

2012-10-01

Contrast-enhanced endoscopic ultrasonography (CE-EUS) was introduced in the early 1990s. The concept of the injection of carbon dioxide microbubbles into the hepatic artery as a contrast material (enhanced ultrasonography) led to "endoscopic ultrasonographic angiography". After the arrival of the first-generation contrast agent, high-frequency (12 MHz) EUS brought about the enhancement of EUS images in the diagnosis of pancreatico-biliary diseases, upper gastrointestinal (GI) cancer, and submucosal tumors. The electronic scanning endosonoscope with both radial and linear probes enabled the use of high-end ultrasound machines and depicted the enhancement of both color/power Doppler flow-based imaging and harmonic-based imaging using second-generation contrast agents. Many reports have described the usefulness of the differential diagnosis of pancreatic diseases and other abdominal lesions. Quantitative evaluation of CE-EUS images was an objective method of diagnosis using the time-intensity curve (TIC), but it was limited to the region of interest. Recently developed Inflow Time Mapping™ can be generated from stored clips and used to display the pattern of signal enhancement with time after injection, offering temporal difference of contrast agents and improved tumor characterization. On the other hand, three-dimensional CE-EUS images added new information to the literature, but lacked positional information. Three-dimensional CE-EUS with accurate positional information is awaited. To date, most reports have been related to pancreatic lesions or lymph nodes. Hemodynamic analysis might be of use for diseases in other organs: upper GI cancer diagnosis, submucosal tumors, and biliary disorders, and it might also provide functional information. Studies of CE-EUS in diseases in many other organs will increase in the near future.

Contrast agent enhanced pQCT of articular cartilage

NASA Astrophysics Data System (ADS)

Kallioniemi, A. S.; Jurvelin, J. S.; Nieminen, M. T.; Lammi, M. J.; Töyräs, J.

2007-02-01

The delayed gadolinium enhanced MRI of cartilage (dGEMRIC) technique is the only non-invasive means to estimate proteoglycan (PG) content in articular cartilage. In dGEMRIC, the anionic paramagnetic contrast agent gadopentetate distributes in inverse relation to negatively charged PGs, leading to a linear relation between T1,Gd and spatial PG content in tissue. In the present study, for the first time, contrast agent enhanced peripheral quantitative computed tomography (pQCT) was applied, analogously to dGEMRIC, for the quantitative detection of spatial PG content in cartilage. The suitability of two anionic radiographic contrast agents, gadopentetate and ioxaglate, to detect enzymatically induced PG depletion in articular cartilage was investigated. First, the interrelationships of x-ray absorption, as measured with pQCT, and the contrast agent solution concentration were investigated. Optimal contrast agent concentrations for the following experiments were selected. Second, diffusion rates for both contrast agents were investigated in intact (n = 3) and trypsin-degraded (n = 3) bovine patellar cartilage. The contrast agent concentration of the cartilaginous layer was measured prior to and 2-27 h after immersion. Optimal immersion time for the further experiments was selected. Third, the suitability of gadopentetate and ioxaglate enhanced pQCT to detect the enzymatically induced specific PG depletion was investigated by determining the contrast agent concentrations and uronic acid and water contents in digested and intact osteochondral samples (n = 16). After trypsin-induced PG loss (-70%, p < 0.05) the penetration of gadopentetate and ioxaglate increased (p < 0.05) by 34% and 48%, respectively. Gadopentetate and ioxaglate concentrations both showed strong correlation (r = -0.95, r = -0.94, p < 0.01, respectively) with the uronic acid content. To conclude, contrast agent enhanced pQCT provides a technique to quantify PG content in normal and experimentally

Contrast-enhanced fluid-attenuated inversion recovery vs. contrast-enhanced spin echo T1-weighted brain imaging.

PubMed

Falzone, Cristian; Rossi, Federica; Calistri, Maurizio; Tranquillo, Massimo; Baroni, Massimo

2008-01-01

In humans, contrast-enhanced fluid-attenuated inversion recovery (FLAIR) imaging plays an important role in detecting brain disease. The aim of this study was to define the clinical utility of contrast-enhanced FLAIR imaging by comparing the results with those with contrast-enhanced spin echo T1-weighted images (SE T1WI) in animals with different brain disorders. Forty-one dogs and five cats with a clinical suspicion of brain disease and 30 normal animals (25 dogs and five cats) were evaluated using a 0.2 T permanent magnet. Before contrast medium injection, spin echo T1-weighted, SE T1WI, and FLAIR sequences were acquired in three planes. SE T1WI and FLAIR images were also acquired after gadolinium injection. Sensitivity in detecting the number, location, margin, and enhancement pattern and rate were evaluated. No lesions were found in a normal animal. In affected animals, 48 lesions in 34 patients were detected in contrast-enhanced SE T1WI whereas 81 lesions in 44 patients were detected in contrast-enhanced FLAIR images. There was no difference in the characteristics of the margins or enhancement pattern of the detected lesions. The objective enhancement rate, the mean value between lesion-to-white matter ratio and lesion-to-gray matter ratio, although representing an overlap of T1 and T2 effects and not pure contrast medium shortening of T1 relaxation, was better in contrast-enhanced FLAIR images. These results suggest a superiority of contrast-enhanced FLAIR images as compared with contrast-enhanced SE T1WI in detecting enhancing brain lesions.

Contrast-enhanced endoscopic ultrasonography: advance and current status

PubMed Central

2014-01-01

Endoscopic ultrasonography (EUS) technology has undergone a great deal of progress along with the color and power Doppler imaging, three-dimensional imaging, electronic scanning, tissue harmonic imaging, and elastography, and one of the most important developments is the ability to acquire contrast-enhanced images. The blood flow in small vessels and the parenchymal microvasculature of the target lesion can be observed non-invasively by contrast-enhanced EUS (CE-EUS). Through a hemodynamic analysis, CE-EUS permits the diagnosis of various gastrointestinal diseases and differential diagnoses between benign and malignant tumors. Recently, mechanical innovations and the development of contrast agents have increased the use of CE-EUS in the diagnostic field, as well as for the assessment of the efficacy of therapeutic agents. The advances in and the current status of CE-EUS are discussed in this review. PMID:25038805

Quantitative characterization of edge enhancement in phase contrast x-ray imaging.

PubMed

Monnin, P; Bulling, S; Hoszowska, J; Valley, J F; Meuli, R; Verdun, F R

2004-06-01

The aim of this study was to model the edge enhancement effect in in-line holography phase contrast imaging. A simple analytical approach was used to quantify refraction and interference contrasts in terms of beam energy and imaging geometry. The model was applied to predict the peak intensity and frequency of the edge enhancement for images of cylindrical fibers. The calculations were compared with measurements, and the relationship between the spatial resolution of the detector and the amplitude of the phase contrast signal was investigated. Calculations using the analytical model were in good agreement with experimental results for nylon, aluminum and copper wires of 50 to 240 microm diameter, and with numerical simulations based on Fresnel-Kirchhoff theory. A relationship between the defocusing distance and the pixel size of the image detector was established. This analytical model is a useful tool for optimizing imaging parameters in phase contrast in-line holography, including defocusing distance, detector resolution and beam energy.

Quantifying activation of perfluorocarbon-based phase-change contrast agents using simultaneous acoustic and optical observation.

PubMed

Li, Sinan; Lin, Shengtao; Cheng, Yi; Matsunaga, Terry O; Eckersley, Robert J; Tang, Meng-Xing

2015-05-01

Phase-change contrast agents in the form of nanoscale droplets can be activated into microbubbles by ultrasound, extending the contrast beyond the vasculature. This article describes simultaneous optical and acoustical measurements for quantifying the ultrasound activation of phase-change contrast agents over a range of concentrations. In experiments, decafluorobutane-based nanodroplets of different dilutions were sonicated with a high-pressure activation pulse and two low-pressure interrogation pulses immediately before and after the activation pulse. The differences between the pre- and post-interrogation signals were calculated to quantify the acoustic power scattered by the microbubbles activated over a range of droplet concentrations. Optical observation occurred simultaneously with the acoustic measurement, and the pre- and post-microscopy images were processed to generate an independent quantitative indicator of the activated microbubble concentration. Both optical and acoustic measurements revealed linear relationships to the droplet concentration at a low concentration range <10(8)/mL when measured at body temperature. Further increases in droplet concentration resulted in saturation of the acoustic interrogation signal. Compared with body temperature, room temperature was found to produce much fewer and larger bubbles after ultrasound droplet activation. Copyright © 2015. Published by Elsevier Inc.

Elevated arousal levels enhance contrast perception.

PubMed

Kim, Dongho; Lokey, Savannah; Ling, Sam

2017-02-01

Our state of arousal fluctuates from moment to moment-fluctuations that can have profound impacts on behavior. Arousal has been proposed to play a powerful, widespread role in the brain, influencing processes as far ranging as perception, memory, learning, and decision making. Although arousal clearly plays a critical role in modulating behavior, the mechanisms underlying this modulation remain poorly understood. To address this knowledge gap, we examined the modulatory role of arousal on one of the cornerstones of visual perception: contrast perception. Using a reward-driven paradigm to manipulate arousal state, we discovered that elevated arousal state substantially enhances visual sensitivity, incurring a multiplicative modulation of contrast response. Contrast defines vision, determining whether objects appear visible or invisible to us, and these results indicate that one of the consequences of decreased arousal state is an impaired ability to visually process our environment.

Contrast-enhanced sonography in pediatrics.

PubMed

McCarville, M Beth

2011-05-01

Microbubble US contrast agents are composed of an outer shell of protein, phospholipid or polymer that encase air or perfluorocarbon gas. These contrast agents have been widely used in adult cardiology patients to improve endocardial border delineation and have been proved safe and well tolerated in this patient population. There is also a growing body of literature elucidating the value of contrast-enhanced sonography to distinguish benign from malignant liver lesions in adults and to characterize non-hepatic adult malignancies. Because these agents have not been approved for pediatric use in many countries, less is known of the value of contrast-enhanced sonography in children. In this review I will discuss several proven and potential pediatric applications of contrast-enhanced sonography.

Can Contrast-Enhanced Sonography Detect Bowel Wall Fibrosis in Mixed Inflammatory and Fibrotic Crohn Disease Lesions in an Animal Model?

PubMed

Dillman, Jonathan R; Rubin, Jonathan M; Johnson, Laura A; Moons, David S; Higgins, Peter D R

2017-03-01

To determine whether contrast-enhanced sonographic quantitative perfusion parameters can detect bowel wall fibrosis in the setting of mixed inflammatory and fibrotic lesions in a Crohn disease animal model. This study was approved by the institutional Committee on the Use and Care of Animals. Multiple (range, 1-5) 2,4,6-trinitrobenzenesulfonic acid-ethanol enemas were used to create intestinal inflammatory lesions with variable fibrosis in female Lewis rats. Low-mechanical index contrast-enhanced sonography was performed 3 days after the final enema using a 0.2-mL bolus of sulfur hexafluoride microbubbles injected through a tail vein. Contrast-enhanced sonographic data were analyzed with software that converts video data into echo-power (linearized) data. Colorectal lesions were scored for histopathologic inflammation and fibrosis; bowel wall collagen was quantified by Western blotting. The Spearman correlation was used to assess associations between contrast-enhanced sonographic quantitative parameters and bowel wall collagen; the Kruskal-Wallis test was used to compare continuous results between histopathologic groups. Thirty-one animals were included in our analysis. Animals were placed into 3 histopathologic cohorts: (1) severe bowel wall inflammation/minimal or no fibrosis (n = 11); (2) severe bowel wall inflammation/moderate fibrosis (n = 9); and (3) severe bowel wall inflammation/severe fibrosis (n = 11). Western blotting showed a significant difference in bowel wall collagen between histopathologic cohorts (P = .0001). There was no correlation between any contrast-enhanced sonographic quantitative parameter and bowel wall collagen (P > .05). There was no difference between histopathologic cohorts for any contrast-enhanced sonographic quantitative parameter (P > .05). Contrast-enhanced sonographic quantitative perfusion parameters failed to effectively detect bowel wall fibrosis in the setting of superimposed inflammation in a Crohn

Quantitative contrast-enhanced optical coherence tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winetraub, Yonatan; SoRelle, Elliott D.; Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305

2016-01-11

We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within amore » voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects.« less

Vascular applications of contrast-enhanced ultrasound imaging.

PubMed

Mehta, Kunal S; Lee, Jake J; Taha, Ashraf G; Avgerinos, Efthymios; Chaer, Rabih A

2017-07-01

Contrast-enhanced ultrasound (CEUS) imaging is a powerful noninvasive modality offering numerous potential diagnostic and therapeutic applications in vascular medicine. CEUS imaging uses microbubble contrast agents composed of an encapsulating shell surrounding a gaseous core. These microbubbles act as nearly perfect intravascular reflectors of ultrasound energy and may be used to enhance the overall contrast and quality of ultrasound images. The purpose of this narrative review is to survey the current literature regarding CEUS imaging and discuss its diagnostic and therapeutic roles in current vascular and selected nonvascular applications. The PubMed, MEDLINE, and Embase databases were searched until July 2016 using the PubMed and Ovid Web-based search engines. The search terms used included contrast-enhanced, microbubble, ultrasound, carotid, aneurysm, and arterial. The diagnostic and therapeutic utility of CEUS imaging has grown exponentially, particularly in the realms of extracranial carotid arterial disease, aortic disease, and peripheral arterial disease. Studies have demonstrated that CEUS imaging is diagnostically superior to conventional ultrasound imaging in identifying vessel irregularities and measuring neovascularization to assess plaque vulnerability and end-muscle perfusion. Groups have begun to use microbubbles as agents in therapeutic applications for targeted drug and gene therapy delivery as well as for the enhancement of sonothrombolysis. The emerging technology of microbubbles and CEUS imaging holds considerable promise for cardiovascular medicine and cancer therapy given its diagnostic and therapeutic utility. Overall, with proper training and credentialing of technicians, the clinical implications are innumerable as microbubble technology is rapidly bursting onto the scene of cardiovascular medicine. Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Inherent Contrast in Magnetic Resonance Imaging and the Potential for Contrast Enhancement

PubMed Central

Brasch, Robert C.

1985-01-01

Magnetic resonance (MR) imaging is emerging as a powerful new diagnostic tool valued for its apparent lack of adverse effects. The excellent inherent contrast between biologic tissues and fluids afforded by MR imaging is one of the foremost characteristics of this technique and depends on physicochemical properties such as hydrogen density and T1 and T2 relaxation rates, on magnetic field strength and on operator-chosen factors for acquiring the MR imaging signal. Pharmaceutical contrast-enhancing agents shorten the MR imaging process and improve sensitivity and diagnostic accuracy. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6.Figure 8.Figure 9.Figure 10.Figure 11. PMID:2992172

Quantitative contrast-enhanced spectral mammography based on photon-counting detectors: A feasibility study.

PubMed

Ding, Huanjun; Molloi, Sabee

2017-08-01

, the correlation slope and offset values were strongly dependent on the total breast thickness and density. The results of this study suggest that iodine mass thickness for cm-scale lesions can be accurately quantified with contrast-enhanced spectral mammography. The quantitative information can potentially improve the differential power for malignancy. © 2017 American Association of Physicists in Medicine.

Clinical utility of three-dimensional contrast-enhanced ultrasound in the differentiation between noninvasive and invasive neoplasms of urinary bladder.

PubMed

Li, Qiu-yang; Tang, Jie; He, En-hui; Li, Yan-mi; Zhou, Yun; Zhang, Xu; Chen, Guangfu

2012-11-01

The purpose of this study was to evaluate the effectiveness of three-dimensional contrast-enhanced ultrasound in differentiating invasive and noninvasive neoplasms of urinary bladder. A total of 60 lesions in 60 consecutive patients with bladder tumors received three dimensional ultrasonography, low acoustic power contrast enhanced ultrasonography and low acoustic power three-dimensional contrast-enhanced ultrasound examination. The IU22 ultrasound scanner and a volume transducer were used and the ultrasound contrast agent was SonoVue. The contrast-specific sonographic imaging modes were PI (pulse inversion) and PM (power modulation). The three dimensional ultrasonography, contrast enhanced ultrasonography, and three-dimensional contrast-enhanced ultrasound images were independently reviewed by two readers who were not in the images acquisition. Images were analyzed off-site. A level of confidence in the diagnosis of tumor invasion of the muscle layer was assigned on a 5° scale. Receiver operating characteristic analysis was used to assess overall confidence in the diagnosis of muscle invasion by tumor. Kappa values were used to assess inter-readers agreement. Histologic diagnosis was obtained for all patients. Final pathologic staging revealed 44 noninvasive tumors and 16 invasive tumors. Three-dimensional contrast-enhanced ultrasound depicted all 16 muscle-invasive tumors. The diagnostic performance of three-dimensional contrast-enhanced ultrasound was better than those of three dimensional ultrasonography and contrast enhanced ultrasonography. The receiver operating characteristic curves were 0.976 and 0.967 for three-dimensional contrast-enhanced ultrasound, those for three dimensional ultrasonography were 0.881 and 0.869, those for contrast enhanced ultrasonography were 0.927 and 0.929. The kappa values in the three dimensional ultrasonography, contrast enhanced ultrasonography and three-dimensional contrast-enhanced ultrasound for inter-reader agreements

A contrast enhancement method for improving the segmentation of breast lesions on ultrasonography.

PubMed

Flores, Wilfrido Gómez; Pereira, Wagner Coelho de Albuquerque

2017-01-01

This paper presents an adaptive contrast enhancement method based on sigmoidal mapping function (SACE) used for improving the computerized segmentation of breast lesions on ultrasound. First, from the original ultrasound image an intensity variation map is obtained, which is used to generate local sigmoidal mapping functions related to distinct contextual regions. Then, a bilinear interpolation scheme is used to transform every original pixel to a new gray level value. Also, four contrast enhancement techniques widely used in breast ultrasound enhancement are implemented: histogram equalization (HEQ), contrast limited adaptive histogram equalization (CLAHE), fuzzy enhancement (FEN), and sigmoid based enhancement (SEN). In addition, these contrast enhancement techniques are considered in a computerized lesion segmentation scheme based on watershed transformation. The performance comparison among techniques is assessed in terms of both the quality of contrast enhancement and the segmentation accuracy. The former is quantified by the measure, where the greater the value, the better the contrast enhancement, whereas the latter is calculated by the Jaccard index, which should tend towards unity to indicate adequate segmentation. The experiments consider a data set with 500 breast ultrasound images. The results show that SACE outperforms its counterparts, where the median values for the measure are: SACE: 139.4, SEN: 68.2, HEQ: 64.1, CLAHE: 62.8, and FEN: 7.9. Considering the segmentation performance results, the SACE method presents the largest accuracy, where the median values for the Jaccard index are: SACE: 0.81, FEN: 0.80, CLAHE: 0.79, HEQ: 77, and SEN: 0.63. The SACE method performs well due to the combination of three elements: (1) the intensity variation map reduces intensity variations that could distort the real response of the mapping function, (2) the sigmoidal mapping function enhances the gray level range where the transition between lesion and background

Naturalness preservation image contrast enhancement via histogram modification

NASA Astrophysics Data System (ADS)

Tian, Qi-Chong; Cohen, Laurent D.

2018-04-01

Contrast enhancement is a technique for enhancing image contrast to obtain better visual quality. Since many existing contrast enhancement algorithms usually produce over-enhanced results, the naturalness preservation is needed to be considered in the framework of image contrast enhancement. This paper proposes a naturalness preservation contrast enhancement method, which adopts the histogram matching to improve the contrast and uses the image quality assessment to automatically select the optimal target histogram. The contrast improvement and the naturalness preservation are both considered in the target histogram, so this method can avoid the over-enhancement problem. In the proposed method, the optimal target histogram is a weighted sum of the original histogram, the uniform histogram, and the Gaussian-shaped histogram. Then the structural metric and the statistical naturalness metric are used to determine the weights of corresponding histograms. At last, the contrast-enhanced image is obtained via matching the optimal target histogram. The experiments demonstrate the proposed method outperforms the compared histogram-based contrast enhancement algorithms.

High Resolution X-ray Phase Contrast Imaging with Acoustic Tissue-Selective Contrast Enhancement

DTIC Science & Technology

2008-06-01

Imaging with Acoustic Tissue-Selective Contrast Enhancement PRINCIPAL INVESTIGATOR: Gerald J. Diebold, Ph.D. CONTRACTING... Contrast Imaging with Acoustic Tissue-Selective Contrast Enhancement 5b. GRANT NUMBER W81XWH-04-1-0481 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...additional phase contrast features are visible at the interfaces of soft tissues as slight contrast enhancements . The image sequence in Fig. 2 shows an image

[Contrast enhanced power Doppler and color Doppler ultrasound in breast masses: Efficiency in diagnosis and contributions to differential diagnosis].

PubMed

Algül, Ali; Balci, Pinar; Seçil, Mustafa; Canda, Tülay

2003-06-01

To compare ability of detection of vascular structures by utilizing ultrasonographic contrast agent (Levovist) prior to and following power Doppler ultrasound (PDUS) and colour Doppler ultrasound (CDUS) and to determine useful parameters in the differentiation of malignant and benign breast masses by means of verified data. Vascularisation characteristics of 38 breast masses (22 malignant, 16 benign) which were confirmed by mammography and B-mode sonography were evaluated by both CDUS and PDUS following and prior to intravenous contrast application. In addition, Vmax and RI values of vascular structures were calculated by Doppler spectral evaluation. Malignant lesions showed more vascularity than benign lesions both with and without contrast enhancement. With both methods, by utilizing contrast agent, central, penetrating and tortuous vascular structures became more significant in malignant lesions when compared with benign lesions. PDUS was able to detect vascular structures better than CDUS; however, the difference was not statistically significant. Presence of peripheral vascularity was not useful in differentiating malignant from benign lesions. Vmax and RI values were higher in malignant lesions and the difference was statistically significant. In both methods, Vmax > 15 cm/sec and RI > 0.80 (CDUS), and RI > 0.70 (PDUS) were accepted as malignancy parameters. Vascular patterns of breast masses as determined with PDUS and CDUS with contrast enhancement and Doppler spectral examinations enabled differentiation of malignant and benign breast lesions. Thus, it is possible to decrease the number of unnecessary surgical interventions.

Comparison of Oral Contrast-Enhanced Transabdominal Ultrasound Imaging With Transverse Contrast-Enhanced Computed Tomography in Preoperative Tumor Staging of Advanced Gastric Carcinoma.

PubMed

He, Xuemei; Sun, Jing; Huang, Xiaoling; Zeng, Chun; Ge, Yinggang; Zhang, Jun; Wu, Jingxian

2017-12-01

This study assessed the diagnostic performance of transabdominal oral contrast-enhanced ultrasound (US) imaging for preoperative tumor staging of advanced gastric carcinoma by comparing it with transverse contrast-enhanced computed tomography (CT). This retrospective study included 42 patients with advanced gastric cancer who underwent laparoscopy, radical surgery, or palliative surgery because of serious complications and had a body mass index of less than 25 kg/m 2 . A cereal-based oral contrast agent was used for transabdominal oral contrast-enhanced US. Retrospective analyses were conducted using preoperative tumor staging data acquired by either transabdominal oral contrast-enhanced US or transverse contrast-enhanced CT. Both contrast-enhanced US and contrast-enhanced CT examinations were reviewed by 2 experienced radiologists independently for preoperative tumor staging according to the seventh edition of the TNM classification. The accuracy, sensitivity, and specificity were calculated by comparing the results of contrast-enhanced US and contrast-enhanced CT with pathologic findings. The overall accuracies of the imaging modalities were compared by the McNemar test. No significant difference was noted in the overall accuracy of transabdominal oral contrast-enhanced US (86% [36 of 42]) and transverse contrast-enhanced CT (83% [35 of 42] P > .999). For stage T2 to T4 gastric cancer, the accuracies of transabdominal oral contrast-enhanced US were 88%, 86%, and 98%, respectively, and those of transverse contrast-enhanced CT were 93%, 83%, and 90%. The overall accuracy of transabdominal oral contrast-enhanced US was comparable with that of transverse contrast-enhanced CT for preoperative tumor staging of advanced gastric cancer. © 2017 by the American Institute of Ultrasound in Medicine.

Limitations of contrast enhancement for infrared target identification

NASA Astrophysics Data System (ADS)

Du Bosq, Todd W.; Fanning, Jonathan D.

2009-05-01

Contrast enhancement and dynamic range compression are currently being used to improve the performance of infrared imagers by increasing the contrast between the target and the scene content. Automatic contrast enhancement techniques do not always achieve this improvement. In some cases, the contrast can increase to a level of target saturation. This paper assesses the range-performance effects of contrast enhancement for target identification as a function of image saturation. Human perception experiments were performed to determine field performance using contrast enhancement on the U.S. Army RDECOM CERDEC NVESD standard military eight target set using an un-cooled LWIR camera. The experiments compare the identification performance of observers viewing contrast enhancement processed images at various levels of saturation. Contrast enhancement is modeled in the U.S. Army thermal target acquisition model (NVThermIP) by changing the scene contrast temperature. The model predicts improved performance based on any improved target contrast, regardless of specific feature saturation or enhancement. The measured results follow the predicted performance based on the target task difficulty metric used in NVThermIP for the non-saturated cases. The saturated images reduce the information contained in the target and performance suffers. The model treats the contrast of the target as uniform over spatial frequency. As the contrast is enhanced, the model assumes that the contrast is enhanced uniformly over the spatial frequencies. After saturation, the spatial cues that differentiate one tank from another are located in a limited band of spatial frequencies. A frequency dependent treatment of target contrast is needed to predict performance of over-processed images.

Contrast-enhanced harmonic ultrasound imaging in ablation therapy for primary hepatocellular carcinoma.

PubMed

Minami, Yasunori; Kudo, Masatoshi

2009-12-31

The success rate of percutaneous radiofrequency (RF) ablation for hepatocellular carcinoma (HCC) depends on correct targeting via an imaging technique. However, RF electrode insertion is not completely accurate for residual HCC nodules because B-mode ultrasound (US), color Doppler, and power Doppler US findings cannot adequately differentiate between treated and viable residual tumor tissue. Electrode insertion is also difficult when we must identify the true HCC nodule among many large regenerated nodules in cirrhotic liver. Two breakthroughs in the field of US technology, harmonic imaging and the development of second-generation contrast agents, have recently been described and have demonstrated the potential to dramatically broaden the scope of US diagnosis of hepatic lesions. Contrast-enhanced harmonic US imaging with an intravenous contrast agent can evaluate small hypervascular HCC even when B-mode US cannot adequately characterize tumor. Therefore, contrast-enhanced harmonic US can facilitate RF ablation electrode placement in hypervascular HCC, which is poorly depicted by B-mode US. The use of contrast-enhanced harmonic US in ablation therapy for liver cancer is an efficient approach.

Contrast enhanced spectroscopic optical coherence tomography

NASA Technical Reports Server (NTRS)

Xu, Chenyang (Inventor); Boppart, Stephen A. (Inventor)

2010-01-01

A method of forming an image of a sample includes performing SOCT on a sample. The sample may include a contrast agent, which may include an absorbing agent and/or a scattering agent. A method of forming an image of tissue may include selecting a contrast agent, delivering the contrast agent to the tissue, acquiring SOCT data from the tissue, and converting the SOCT data into an image. The contributions to the SOCT data of an absorbing agent and a scattering agent in a sample may be quantified separately.

Balance Contrast Enhancement using piecewise linear stretching

NASA Astrophysics Data System (ADS)

Rahavan, R. V.; Govil, R. C.

1993-04-01

Balance Contrast Enhancement is one of the techniques employed to produce color composites with increased color contrast. It equalizes the three images used for color composition in range and mean. This results in a color composite with large variation in hue. Here, it is shown that piecewise linear stretching can be used for performing the Balance Contrast Enhancement. In comparison with the Balance Contrast Enhancement Technique using parabolic segment as transfer function (BCETP), the method presented here is algorithmically simple, constraint-free and produces comparable results.

Gadolinium-enhanced MR images of the growing piglet skeleton: ionic versus nonionic contrast agent.

PubMed

Menezes, Nina M; Olear, Elizabeth A; Li, Xiaoming; Connolly, Susan A; Zurakowski, David; Foley, Mary; Shapiro, Frederic; Jaramillo, Diego

2006-05-01

To determine whether there are differences in the distribution of ionic and nonionic gadolinium-based contrast agents by evaluating contrast enhancement of the physis, epiphyseal cartilage, secondary ossification center, and metaphysis in the knees of normal piglets. Following approval from the Subcommittee on Research Animal Care, knees of 12 3-week-old piglets were imaged at 3-T magnetic resonance (MR) imaging after intravenous injection of gadoteridol (nonionic contrast agent; n = 6) or gadopentetate dimeglumine (ionic contrast agent; n = 6). Early enhancement evaluation with gradient-echo MR imaging was quantified and compared (Student t test) by means of enhancement ratios. Distribution of contrast material was assessed and compared (Student t test) by means of T1 measurements obtained before and at three 15-minute intervals after contrast agent administration. The relative visibility of the physis, epiphyseal cartilage, secondary ossification center, and metaphysis was qualitatively assessed by two observers and compared (Wilcoxon signed rank test). Differences in matrix content and cellularity that might explain the imaging findings were studied at histologic evaluation. Enhancement ratios were significantly higher for gadoteridol than for gadopentetate dimeglumine in the physis, epiphyseal cartilage, and secondary ossification center (P < .05). After contrast agent administration, T1 values decreased sharply for both agents-but more so for gadoteridol. Additionally, there was less variability in T1 values across structures with this contrast agent. Gadoteridol resulted in greater visibility of the physis, while gadopentetate dimeglumine resulted in greater contrast between the physis and metaphysis (P < .05). The results suggest different roles for the two gadolinium-based contrast agents: The nonionic contrast medium is better suited for evaluating perfusion and anatomic definition in the immature skeleton, while the ionic contrast medium is better for

Contrast-Enhanced Magnetic Resonance Imaging of Gastric Emptying and Motility in Rats.

PubMed

Lu, Kun-Han; Cao, Jiayue; Oleson, Steven Thomas; Powley, Terry L; Liu, Zhongming

2017-11-01

The assessment of gastric emptying and motility in humans and animals typically requires radioactive imaging or invasive measurements. Here, we developed a robust strategy to image and characterize gastric emptying and motility in rats based on contrast-enhanced magnetic resonance imaging (MRI) and computer-assisted image processing. The animals were trained to naturally consume a gadolinium-labeled dietgel while bypassing any need for oral gavage. Following this test meal, the animals were scanned under low-dose anesthesia for high-resolution T1-weighted MRI in 7 Tesla, visualizing the time-varying distribution of the meal with greatly enhanced contrast against non-gastrointestinal (GI) tissues. Such contrast-enhanced images not only depicted the gastric anatomy, but also captured and quantified stomach emptying, intestinal filling, antral contraction, and intestinal absorption with fully automated image processing. Over four postingestion hours, the stomach emptied by 27%, largely attributed to the emptying of the forestomach rather than the corpus and the antrum, and most notable during the first 30 min. Stomach emptying was accompanied by intestinal filling for the first 2 h, whereas afterward intestinal absorption was observable as cumulative contrast enhancement in the renal medulla. The antral contraction was captured as a peristaltic wave propagating from the proximal to distal antrum. The frequency, velocity, and amplitude of the antral contraction were on average 6.34 ± 0.07 contractions per minute, 0.67 ± 0.01 mm/s, and 30.58 ± 1.03%, respectively. These results demonstrate an optimized MRI-based strategy to assess gastric emptying and motility in healthy rats, paving the way for using this technique to understand GI diseases, or test new therapeutics in rat models.The assessment of gastric emptying and motility in humans and animals typically requires radioactive imaging or invasive measurements. Here, we developed a robust strategy to image and

Detection and characterization of murine colitis and carcinogenesis by molecularly targeted contrast-enhanced ultrasound

PubMed Central

Brückner, Markus; Heidemann, Jan; Nowacki, Tobias M; Cordes, Friederike; Stypmann, Jörg; Lenz, Philipp; Gohar, Faekah; Lügering, Andreas; Bettenworth, Dominik

2017-01-01

AIM To study mucosal addressin cellular adhesion molecule-1 (MAdCAM-1) and vascular endothelial growth factor (VEGF)-targeted contrast enhanced ultrasound (CEUS) for the assessment of murine colitis and carcinogenesis. METHODS C57BL/6 mice were challenged with 3% dextran sodium-sulfate (DSS) for three, six or nine days to study the development of acute colitis. Ultrasound was performed with and without the addition of unspecific contrast agents. MAdCAM-1-targeted contrast agent was used to detect and quantify MAdCAM-1 expression. Inflammatory driven colorectal azoxymethane (AOM)/DSS-induced carcinogenesis was examined on day 42 and 84 using VEGF-targeted contrast agent. Highly specific tissue echogenicity was quantified using specialized software. Sonographic findings were correlated to tissue staining, western blot analysis and immunohistochemistry to quantify the degree of inflammation and stage of carcinogenesis. RESULTS Native ultrasound detected increased general bowel wall thickening that correlated with more progressed and more severe DSS-colitis (healthy mice: 0.3 mm ± 0.03 vs six days DSS: 0.5 mm ± 0.2 vs nine days DSS: 0.6 mm ± 0.2, P < 0.05). Moreover, these sonographic findings correlated well with clinical parameters such as weight loss (r2 = 0.74) and histological damage (r2 = 0.86) (P < 0.01). In acute DSS-induced murine colitis, CEUS targeted against MAdCAM-1 detected and differentiated stages of mild, moderate and severe colitis via calculation of mean pixel contrast intensity in decibel (9.6 dB ± 1.6 vs 12.9 dB ± 1.4 vs 18 dB ± 3.33, P < 0.05). Employing the AOM/DSS-induced carcinogenesis model, tumor development was monitored by CEUS targeted against VEGF and detected a significantly increased echogenicity in tumors as compared to adjacent healthy mucosa (healthy mucosa, 1.6 dB ± 1.4 vs 42 d, 18.2 dB ± 3.3 vs 84 d, 18.6 dB ± 4.9, P < 0.01). Tissue echogenicity strongly correlated with histological analysis and immunohistochemistry

Detection and characterization of murine colitis and carcinogenesis by molecularly targeted contrast-enhanced ultrasound.

PubMed

Brückner, Markus; Heidemann, Jan; Nowacki, Tobias M; Cordes, Friederike; Stypmann, Jörg; Lenz, Philipp; Gohar, Faekah; Lügering, Andreas; Bettenworth, Dominik

2017-04-28

To study mucosal addressin cellular adhesion molecule-1 (MAdCAM-1) and vascular endothelial growth factor (VEGF)-targeted contrast enhanced ultrasound (CEUS) for the assessment of murine colitis and carcinogenesis. C57BL/6 mice were challenged with 3% dextran sodium-sulfate (DSS) for three, six or nine days to study the development of acute colitis. Ultrasound was performed with and without the addition of unspecific contrast agents. MAdCAM-1-targeted contrast agent was used to detect and quantify MAdCAM-1 expression. Inflammatory driven colorectal azoxymethane (AOM)/DSS-induced carcinogenesis was examined on day 42 and 84 using VEGF-targeted contrast agent. Highly specific tissue echogenicity was quantified using specialized software. Sonographic findings were correlated to tissue staining, western blot analysis and immunohistochemistry to quantify the degree of inflammation and stage of carcinogenesis. Native ultrasound detected increased general bowel wall thickening that correlated with more progressed and more severe DSS-colitis (healthy mice: 0.3 mm ± 0.03 vs six days DSS: 0.5 mm ± 0.2 vs nine days DSS: 0.6 mm ± 0.2, P < 0.05). Moreover, these sonographic findings correlated well with clinical parameters such as weight loss ( r 2 = 0.74) and histological damage ( r 2 = 0.86) ( P < 0.01). In acute DSS-induced murine colitis, CEUS targeted against MAdCAM-1 detected and differentiated stages of mild, moderate and severe colitis via calculation of mean pixel contrast intensity in decibel (9.6 dB ± 1.6 vs 12.9 dB ± 1.4 vs 18 dB ± 3.33, P < 0.05). Employing the AOM/DSS-induced carcinogenesis model, tumor development was monitored by CEUS targeted against VEGF and detected a significantly increased echogenicity in tumors as compared to adjacent healthy mucosa (healthy mucosa, 1.6 dB ± 1.4 vs 42 d, 18.2 dB ± 3.3 vs 84 d, 18.6 dB ± 4.9, P < 0.01). Tissue echogenicity strongly correlated with histological analysis and immunohistochemistry findings (VEGF

Experimentally enhanced model-based deconvolution of propagation-based phase-contrast data

NASA Astrophysics Data System (ADS)

Pichotka, M.; Palma, K.; Hasn, S.; Jakubek, J.; Vavrik, D.

2016-12-01

In recent years phase-contrast has become a much investigated modality in radiographic imaging. The radiographic setups employed in phase-contrast imaging are typically rather costly and complex, e.g. high performance Talbot-Laue interferometers operated at synchrotron light sources. In-line phase-contrast imaging states the most pedestrian approach towards phase-contrast enhancement. Utilizing small angle deflection within the imaged sample and the entailed interference of the deflected and un-deflected beam during spatial propagation, in-line phase-contrast imaging only requires a well collimated X-ray source with a high contrast & high resolution detector. Employing high magnification the above conditions are intrinsically fulfilled in cone-beam micro-tomography. As opposed of 2D imaging, where contrast enhancement is generally considered beneficial, in tomographic modalities the in-line phase-contrast effect can be quite a nuisance since it renders the inverse problem posed by tomographic reconstruction inconsistent, thus causing reconstruction artifacts. We present an experimentally enhanced model-based approach to disentangle absorption and in-line phase-contrast. The approach employs comparison of transmission data to a system model computed iteratively on-line. By comparison of the forward model to absorption data acquired in continuous rotation strong local deviations of the data residual are successively identified as likely candidates for in-line phase-contrast. By inducing minimal vibrations (few mrad) to the sample around the peaks of such deviations the transmission signal can be decomposed into a constant absorptive fraction and an oscillating signal caused by phase-contrast which again allows to generate separate maps for absorption and phase-contrast. The contributions of phase-contrast and the corresponding artifacts are subsequently removed from the tomographic dataset. In principle, if a 3D handling of the sample is available, this method also

[Contrast medium enhanced magnetic resonance tomography of liver metastases: positive versus negative contrast media].

PubMed

Hammerstingl, R M; Schwarz, W; Hochmuth, K; Staib-Sebler, E; Lorenz, M; Vogl, T J

2001-01-01

The development in oncologic liver surgery as well as modified interventional therapy strategies of the liver have resulted in improved diagnostic imaging. The evolution of contrast agents for MR imaging of the liver has proceeded along several different paths with the common goal of improving liver-lesion contrast. In MRI contrast agents act indirectly by their effects on relaxation times. Contrast agents used for hepatic MR imaging can be categorized in those that target the extracellular space, the hepatobiliary system, and the reticuloendothelial system. The first two result in a positive enhancement, the last one in a negative enhancement. Positive enhancers allow a better characterization of liver metastases using dynamic sequence protocols. Detection rate of liver metastases is increased using hepatobiliary contrast-enhanced MRI compared to unenhanced MRI. Negative enhancers, iron oxide particles, significantly increase tumor-to-liver contrast and allow detection of more lesions than other diagnostic methods. Iron-oxide enhanced MRI enables differential diagnosis of liver metastases comparing morphologic features using T2 and T1-weighted sequences.

Complete penile corporeal septation: evaluation with contrast enhanced US.

PubMed

Bertolotto, Michele; Bucci, Stefano; Quaia, Emilio; Coss, Matteo; Liguori, Giovanni

2008-01-01

Complete penile corporeal septation is a rare malformation in which the corpora cavernosa are completely isolated. We describe a new method to reach the diagnosis of this malformation using contrast enhanced US. Two patients with complete penile corporeal septation underwent color Doppler and contrast enhanced US after bilateral cavernosal injection of 10 microg prostaglandin E1. Contrast enhanced US was performed using a contrast specific software (Contrast-Tuned imaging, EsaOte, Genoa, Italy) and a linear transducer designed to evaluate superficial structures. Microbubbles of SonoVue (Bracco, Milan, Italy) were injected in one corpus cavernosum. After cavernosal injection of microbubbles no adverse events were observed. Contrast enhanced US showed unilateral enhancement of the corpus cavernosum in which microbubbles were injected. Cavernosography confirmed unilateral corporeal opacification. Contrast enhanced US can be used effectively to diagnose complete penile corporeal septation.

Quantitative contrast-enhanced mammography for contrast medium kinetics studies

NASA Astrophysics Data System (ADS)

Arvanitis, C. D.; Speller, R.

2009-10-01

Quantitative contrast-enhanced mammography, based on a dual-energy approach, aims to extract quantitative and temporal information of the tumour enhancement after administration of iodinated vascular contrast media. Simulations using analytical expressions and optimization of critical parameters essential for the development of quantitative contrast-enhanced mammography are presented. The procedure has been experimentally evaluated using a tissue-equivalent phantom and an amorphous silicon active matrix flat panel imager. The x-ray beams were produced by a tungsten target tube and spectrally shaped using readily available materials. Measurement of iodine projected thickness in mg cm-2 has been performed. The effect of beam hardening does not introduce nonlinearities in the measurement of iodine projected thickness for values of thicknesses found in clinical investigations. However, scattered radiation introduces significant deviations from slope equal to unity when compared with the actual iodine projected thickness. Scatter correction before the analysis of the dual-energy images provides accurate iodine projected thickness measurements. At 10% of the exposure used in clinical mammography, signal-to-noise ratios in excess of 5 were achieved for iodine projected thicknesses less than 3 mg cm-2 within a 4 cm thick phantom. For the extraction of temporal information, a limited number of low-dose images were used with the phantom incorporating a flow of iodinated contrast medium. The results suggest that spatial and temporal information of iodinated contrast media can be used to indirectly measure the tumour microvessel density and determine its uptake and washout from breast tumours. The proposed method can significantly improve tumour detection in dense breasts. Its application to perform in situ x-ray biopsy and assessment of the oncolytic effect of anticancer agents is foreseeable.

Anatomical noise in contrast-enhanced digital mammography. Part II. Dual-energy imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, Melissa L.; Yaffe, Martin J.; Mainprize, James G.

2013-08-15

Purpose: Dual-energy (DE) contrast-enhanced digital mammography (CEDM) uses an iodinated contrast agent in combination with digital mammography (DM) to evaluate lesions on the basis of tumor angiogenesis. In DE imaging, low-energy (LE) and high-energy (HE) images are acquired after contrast administration and their logarithms are subtracted to cancel the appearance of normal breast tissue. Often there is incomplete signal cancellation in the subtracted images, creating a background “clutter” that can impair lesion detection. This is the second component of a two-part report on anatomical noise in CEDM. In Part I the authors characterized the anatomical noise for single-energy (SE) temporalmore » subtraction CEDM by a power law, with model parameters α and β. In this work the authors quantify the anatomical noise in DE CEDM clinical images and compare this with the noise in SE CEDM. The influence on the anatomical noise of the presence of iodine in the breast, the timing of imaging postcontrast administration, and the x-ray energy used for acquisition are each evaluated.Methods: The power law parameters, α and β, were measured from unprocessed LE and HE images and from DE subtracted images to quantify the anatomical noise. A total of 98 DE CEDM cases acquired in a previous clinical pilot study were assessed. Conventional DM images from 75 of the women were evaluated for comparison with DE CEDM. The influence of the imaging technique on anatomical noise was determined from an analysis of differences between the power law parameters as measured in DM, LE, HE, and DE subtracted images for each subject.Results: In DE CEDM, weighted image subtraction lowers β to about 1.1 from 3.2 and 3.1 in LE and HE unprocessed images, respectively. The presence of iodine has a small but significant effect in LE images, reducing β by about 0.07 compared to DM, with α unchanged. Increasing the x-ray energy, from that typical in DM to a HE beam, significantly decreases α by

Quantitative assessment of placental perfusion by contrast-enhanced ultrasound in macaques and human subjects

PubMed Central

Roberts, Victoria HJ; Lo, Jamie O; Salati, Jennifer A; Lewandowski, Katherine S; Lindner, Jonathan R; Morgan, Terry K; Frias, Antonio E

2016-01-01

Background The utero-placental vascular supply is a critical determinant of placental function and fetal growth. Current methods for the in vivo assessment of placental blood flow are limited. Objective Here we demonstrate the feasibility of utilizing contrast-enhanced ultrasound to visualize and quantify perfusion kinetics in the intervillous space of the primate placenta. Study design Pregnant Japanese macaques were studied at mid second trimester and in the early third trimester. Markers of injury were assessed in placenta samples from animals with or without contrast-enhanced ultrasound exposure (n=6/group). Human subjects were recruited immediately prior to scheduled first trimester pregnancy termination. All studies were performed with maternal intravenous infusion of lipid-shelled octofluoropropane microbubbles with image acquisition using a multipulse contrast-specific algorithm with destruction-replenishment analysis of signal intensity for assessment of perfusion. Results In macaques, rate of perfusion in the intervillous space was increased with advancing gestation. No evidence of microvascular hemorrhage or acute inflammation was found in placental villous tissue and expression levels of caspase-3, nitrotyrosine and HSP70 as markers of apoptosis, nitrative and oxidative stress respectively were unchanged by contrast-enhanced ultrasound exposure. In humans, placental perfusion was visualized at 11wks gestation and preliminary data reveal regional differences in intervillous space perfusion within an individual placenta. By electron microscopy, we demonstrate no evidence of ultrastructure damage to the microvilli on the syncytiotrophoblast following first trimester ultrasound studies. Conclusions Use of contrast-enhanced ultrasound did not result in placental structural damage, and was able to identify intervillous space perfusion rate differences within a placenta. Contrast-enhanced ultrasound may offer a safe clinical tool for the identification of

Visual Contrast Enhancement Algorithm Based on Histogram Equalization

PubMed Central

Ting, Chih-Chung; Wu, Bing-Fei; Chung, Meng-Liang; Chiu, Chung-Cheng; Wu, Ya-Ching

2015-01-01

Image enhancement techniques primarily improve the contrast of an image to lend it a better appearance. One of the popular enhancement methods is histogram equalization (HE) because of its simplicity and effectiveness. However, it is rarely applied to consumer electronics products because it can cause excessive contrast enhancement and feature loss problems. These problems make the images processed by HE look unnatural and introduce unwanted artifacts in them. In this study, a visual contrast enhancement algorithm (VCEA) based on HE is proposed. VCEA considers the requirements of the human visual perception in order to address the drawbacks of HE. It effectively solves the excessive contrast enhancement problem by adjusting the spaces between two adjacent gray values of the HE histogram. In addition, VCEA reduces the effects of the feature loss problem by using the obtained spaces. Furthermore, VCEA enhances the detailed textures of an image to generate an enhanced image with better visual quality. Experimental results show that images obtained by applying VCEA have higher contrast and are more suited to human visual perception than those processed by HE and other HE-based methods. PMID:26184219

Contrast-enhanced magneto-photo-acoustic imaging in vivo using dual-contrast nanoparticles.

PubMed

Qu, Min; Mehrmohammadi, Mohammad; Truby, Ryan; Graf, Iulia; Homan, Kimberly; Emelianov, Stanislav

2014-06-01

By mapping the distribution of targeted plasmonic nanoparticles (NPs), photoacoustic (PA) imaging offers the potential to detect the pathologies in the early stages. However, optical absorption of the endogenous chromophores in the background tissue significantly reduces the contrast resolution of photoacoustic imaging. Previously, we introduced MPA imaging - a synergistic combination of magneto-motive ultrasound (MMUS) and PA imaging, and demonstrated MPA contrast enhancement using cell culture studies. In the current study, contrast enhancement was investigated in vivo using the magneto-photo-acoustic (MPA) imaging augmented with dual-contrast nanoparticles. Liposomal nanoparticles (LNPs) possessing both optical absorption and magnetic properties were injected into a murine tumor model. First, photoacoustic signals were generated from both the endogenous absorbers in the tissue and the liposomal nanoparticles in the tumor. Then, given significant differences in magnetic properties of tissue and LNPs, the magnetic response of LNPs (i.e. MMUS signal) was utilized to suppress the unwanted PA signals from the background tissue and thus improves the PA imaging contrast. In this study, we demonstrated the 3D MPA image of LNP-labeled xenografted tumor in a live animal. Compared to conventional PA imaging, the MPA images show significantly enhanced contrast between the nanoparticle-labeled tumor and the background tissue. Our results suggest the feasibility of MPA for high contrast in vivo mapping of dual-contrast nanoparticles.

Contrast-enhanced magneto-photo-acoustic imaging in vivo using dual-contrast nanoparticles☆

PubMed Central

Qu, Min; Mehrmohammadi, Mohammad; Truby, Ryan; Graf, Iulia; Homan, Kimberly; Emelianov, Stanislav

2014-01-01

By mapping the distribution of targeted plasmonic nanoparticles (NPs), photoacoustic (PA) imaging offers the potential to detect the pathologies in the early stages. However, optical absorption of the endogenous chromophores in the background tissue significantly reduces the contrast resolution of photoacoustic imaging. Previously, we introduced MPA imaging – a synergistic combination of magneto-motive ultrasound (MMUS) and PA imaging, and demonstrated MPA contrast enhancement using cell culture studies. In the current study, contrast enhancement was investigated in vivo using the magneto-photo-acoustic (MPA) imaging augmented with dual-contrast nanoparticles. Liposomal nanoparticles (LNPs) possessing both optical absorption and magnetic properties were injected into a murine tumor model. First, photoacoustic signals were generated from both the endogenous absorbers in the tissue and the liposomal nanoparticles in the tumor. Then, given significant differences in magnetic properties of tissue and LNPs, the magnetic response of LNPs (i.e. MMUS signal) was utilized to suppress the unwanted PA signals from the background tissue thus improving the PA imaging contrast. In this study, we demonstrated the 3D MPA imaging of LNP-labeled xenografted tumor in a live animal. Compared to conventional PA imaging, the MPA imaging show significantly enhanced contrast between the nanoparticle-labeled tumor and the background tissue. Our results suggest the feasibility of MPA imaging for high contrast in vivo mapping of dual-contrast nanoparticles. PMID:24653976

Ring-enhancement pattern on contrast-enhanced CT predicts adenosquamous carcinoma of the pancreas: a matched case-control study.

PubMed

Imaoka, Hiroshi; Shimizu, Yasuhiro; Mizuno, Nobumasa; Hara, Kazuo; Hijioka, Susumu; Tajika, Masahiro; Tanaka, Tsutomu; Ishihara, Makoto; Ogura, Takeshi; Obayashi, Tomohiko; Shinagawa, Akihide; Sakaguchi, Masafumi; Yamaura, Hidekazu; Kato, Mina; Niwa, Yasumasa; Yamao, Kenji

2014-01-01

Adenosquamous carcinoma of the pancreas (ASC) is a rare malignant neoplasm of the pancreas, exhibiting both glandular and squamous differentiation. However, little is known about its imaging features. This study examined the imaging features of pancreatic ASC. We evaluated images of contrast-enhanced computed tomography (CT) and endoscopic ultrasonography (EUS). As controls, solid pancreatic neoplasms matched in a 2:1 ratio to ASC cases for age, sex and tumor location were also evaluated. Twenty-three ASC cases were examined, and 46 solid pancreatic neoplasms (43 pancreatic ductal adenocarcinomas, two pancreatic neuroendocrine tumors and one acinar cell carcinoma) were matched as controls. Univariate analysis demonstrated significant differences in the outline and vascularity of tumors on contrast-enhanced CT in the ASC and control groups (P < 0.001 and P < 0.001, respectively). A smooth outline, cystic changes, and the ring-enhancement pattern on contrast-enhanced CT were seen to have significant predictive powers by stepwise forward logistic regression analysis (P = 0.044, P = 0.010, and P = 0.001, respectively). Of the three, the ring-enhancement pattern was the most useful, and its predictive diagnostic sensitivity, specificity, positive predictive value and negative predictive value for diagnosis of ASC were 65.2%, 89.6%, 75.0% and 84.3%, respectively. These results demonstrate that presence of the ring-enhancement pattern on contrast-enhanced CT is the most useful predictive factor for ASC. Copyright © 2014 IAP and EPC. Published by Elsevier B.V. All rights reserved.

Contrast agents in dynamic contrast-enhanced magnetic resonance imaging

PubMed Central

Yan, Yuling; Sun, Xilin; Shen, Baozhong

2017-01-01

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a noninvasive method to assess angiogenesis, which is widely used in clinical applications including diagnosis, monitoring therapy response and prognosis estimation in cancer patients. Contrast agents play a crucial role in DCE-MRI and should be carefully selected in order to improve accuracy in DCE-MRI examination. Over the past decades, there was much progress in the development of optimal contrast agents in DCE-MRI. In this review, we describe the recent research advances in this field and discuss properties of contrast agents, as well as their advantages and disadvantages. Finally, we discuss the research perspectives for improving this promising imaging method. PMID:28415647

Dual-energy contrast-enhanced mammography.

PubMed

Travieso Aja, M M; Rodríguez Rodríguez, M; Alayón Hernández, S; Vega Benítez, V; Luzardo, O P

2014-01-01

The degree of vascularization in breast lesions is related to their malignancy. For this reason, functional diagnostic imaging techniques have become important in recent years. Dual-energy contrast-enhanced mammography is a new, apparently promising technique in breast cancer that provides information about the degree of vascularization of the lesion in addition to the morphological information provided by conventional mammography. This article describes the state of the art for dual-energy contrast-enhanced mammography. Based on 15 months' clinical experience, we illustrate this review with clinical cases that allow us to discuss the advantages and limitations of this technique. Copyright © 2014 SERAM. Published by Elsevier Espana. All rights reserved.

Dual-energy contrast-enhanced spectral mammography (CESM).

PubMed

Daniaux, Martin; De Zordo, Tobias; Santner, Wolfram; Amort, Birgit; Koppelstätter, Florian; Jaschke, Werner; Dromain, Clarisse; Oberaigner, Willi; Hubalek, Michael; Marth, Christian

2015-10-01

Dual-energy contrast-enhanced mammography is one of the latest developments in breast care. Imaging with contrast agents in breast cancer was already known from previous magnetic resonance imaging and computed tomography studies. However, high costs, limited availability-or high radiation dose-led to the development of contrast-enhanced spectral mammography (CESM). We reviewed the current literature, present our experience, discuss the advantages and drawbacks of CESM and look at the future of this innovative technique.

Morphological rational operator for contrast enhancement.

PubMed

Peregrina-Barreto, Hayde; Herrera-Navarro, Ana M; Morales-Hernández, Luis A; Terol-Villalobos, Iván R

2011-03-01

Contrast enhancement is an important task in image processing that is commonly used as a preprocessing step to improve the images for other tasks such as segmentation. However, some methods for contrast improvement that work well in low-contrast regions affect good contrast regions as well. This occurs due to the fact that some elements may vanish. A method focused on images with different luminance conditions is introduced in the present work. The proposed method is based on morphological transformations by reconstruction and rational operations, which, altogether, allow a more accurate contrast enhancement resulting in regions that are in harmony with their environment. Furthermore, due to the properties of these morphological transformations, the creation of new elements on the image is avoided. The processing is carried out on luminance values in the u'v'Y color space, which avoids the creation of new colors. As a result of the previous considerations, the proposed method keeps the natural color appearance of the image.

The Future of Contrast-Enhanced Mammography.

PubMed

Covington, Matthew F; Pizzitola, Victor J; Lorans, Roxanne; Pockaj, Barbara A; Northfelt, Donald W; Appleton, Catherine M; Patel, Bhavika K

2018-02-01

The purpose of this article is to discuss facilitators of and barriers to future implementation of contrast-enhanced mammography (CEM) in the United States. CEM provides low-energy 2D mammographic images analogous to digital mammography and contrast-enhanced recombined images that allow assessment of neovascularity similar to that offered by MRI. The utilization of CEM in the United States is currently low but could increase rapidly given the many potential indications for its clinical use.

Contrast enhancement of transparencies

NASA Technical Reports Server (NTRS)

Shulman, A. R.; Lee, S. H.

1976-01-01

System can enhance or reduce contrast of photographic transparency for printing or projection by using constructive and destructive interference of collimated laser beam. System is potentially less expensive than electronic CRT methods and is more accurate than trial-and-error manual techniques.

Fundamentals of quantitative dynamic contrast-enhanced MR imaging.

PubMed

Paldino, Michael J; Barboriak, Daniel P

2009-05-01

Quantitative analysis of dynamic contrast-enhanced MR imaging (DCE-MR imaging) has the power to provide information regarding physiologic characteristics of the microvasculature and is, therefore, of great potential value to the practice of oncology. In particular, these techniques could have a significant impact on the development of novel anticancer therapies as a promising biomarker of drug activity. Standardization of DCE-MR imaging acquisition and analysis to provide more reproducible measures of tumor vessel physiology is of crucial importance to realize this potential. The purpose of this article is to review the pathophysiologic basis and technical aspects of DCE-MR imaging techniques.

Modeling the effects of contrast enhancement on target acquisition performance

NASA Astrophysics Data System (ADS)

Du Bosq, Todd W.; Fanning, Jonathan D.

2008-04-01

Contrast enhancement and dynamic range compression are currently being used to improve the performance of infrared imagers by increasing the contrast between the target and the scene content, by better utilizing the available gray levels either globally or locally. This paper assesses the range-performance effects of various contrast enhancement algorithms for target identification with well contrasted vehicles. Human perception experiments were performed to determine field performance using contrast enhancement on the U.S. Army RDECOM CERDEC NVESD standard military eight target set using an un-cooled LWIR camera. The experiments compare the identification performance of observers viewing linearly scaled images and various contrast enhancement processed images. Contrast enhancement is modeled in the US Army thermal target acquisition model (NVThermIP) by changing the scene contrast temperature. The model predicts improved performance based on any improved target contrast, regardless of feature saturation or enhancement. To account for the equivalent blur associated with each contrast enhancement algorithm, an additional effective MTF was calculated and added to the model. The measured results are compared with the predicted performance based on the target task difficulty metric used in NVThermIP.

Perceptual Contrast Enhancement with Dynamic Range Adjustment

PubMed Central

Zhang, Hong; Li, Yuecheng; Chen, Hao; Yuan, Ding; Sun, Mingui

2013-01-01

Recent years, although great efforts have been made to improve its performance, few Histogram equalization (HE) methods take human visual perception (HVP) into account explicitly. The human visual system (HVS) is more sensitive to edges than brightness. This paper proposes to take use of this nature intuitively and develops a perceptual contrast enhancement approach with dynamic range adjustment through histogram modification. The use of perceptual contrast connects the image enhancement problem with the HVS. To pre-condition the input image before the HE procedure is implemented, a perceptual contrast map (PCM) is constructed based on the modified Difference of Gaussian (DOG) algorithm. As a result, the contrast of the image is sharpened and high frequency noise is suppressed. A modified Clipped Histogram Equalization (CHE) is also developed which improves visual quality by automatically detecting the dynamic range of the image with improved perceptual contrast. Experimental results show that the new HE algorithm outperforms several state-of-the-art algorithms in improving perceptual contrast and enhancing details. In addition, the new algorithm is simple to implement, making it suitable for real-time applications. PMID:24339452

Contrast-enhanced photoacoustic tomography of human joints

NASA Astrophysics Data System (ADS)

Tian, Chao; Keswani, Rahul K.; Gandikota, Girish; Rosania, Gus R.; Wang, Xueding

2016-03-01

Photoacoustic tomography (PAT) provides a unique tool to diagnose inflammatory arthritis. However, the specificity and sensitivity of PAT based on endogenous contrasts is limited. The development of contrast enhanced PAT imaging modalities in combination with small molecule contrast agents could lead to improvements in diagnosis and treatment of joint disease. Accordingly, we adapted and tested a PAT clinical imaging system for imaging the human joints, in combination with a novel PAT contrast agent derived from an FDA-approved small molecule drug. Imaging results based on a photoacoustic and ultrasound (PA/US) dual-modality system revealed that this contrast-enhanced PAT imaging system may offer additional information beyond single-modality PA or US imaging system, for the imaging, diagnosis and assessment of inflammatory arthritis.

Si-strip photon counting detectors for contrast-enhanced spectral mammography

NASA Astrophysics Data System (ADS)

Chen, Buxin; Reiser, Ingrid; Wessel, Jan C.; Malakhov, Nail; Wawrzyniak, Gregor; Hartsough, Neal E.; Gandhi, Thulasi; Chen, Chin-Tu; Iwanczyk, Jan S.; Barber, William C.

2015-08-01

We report on the development of silicon strip detectors for energy-resolved clinical mammography. Typically, X-ray integrating detectors based on scintillating cesium iodide CsI(Tl) or amorphous selenium (a-Se) are used in most commercial systems. Recently, mammography instrumentation has been introduced based on photon counting Si strip detectors. The required performance for mammography in terms of the output count rate, spatial resolution, and dynamic range must be obtained with sufficient field of view for the application, thus requiring the tiling of pixel arrays and particular scanning techniques. Room temperature Si strip detector, operating as direct conversion x-ray sensors, can provide the required speed when connected to application specific integrated circuits (ASICs) operating at fast peaking times with multiple fixed thresholds per pixel, provided that the sensors are designed for rapid signal formation across the X-ray energy ranges of the application. We present our methods and results from the optimization of Si-strip detectors for contrast enhanced spectral mammography. We describe the method being developed for quantifying iodine contrast using the energy-resolved detector with fixed thresholds. We demonstrate the feasibility of the method by scanning an iodine phantom with clinically relevant contrast levels.

[Injection Pressure Evaluation of the New Venous Catheter with Side Holes for Contrast-enhanced CT/MRI].

PubMed

Fukuda, Junya; Arai, Keisuke; Miyazawa, Hitomi; Kobayashi, Kyouko; Nakamura, Junpei; Suto, Takayuki; Tsushima, Yoshito

2018-01-01

The simulation study was conducted for the new venous catheter with side holes of contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) to evaluate the infusion pressure on four contrast media and several injection speeds. All infusion pressure of the new venous catheter with side holes were less than 15 kg/cm 2 as limitation of extension tube and also reduced the infusion pressure by 15% at the maximum compared to the catheter with single hole. The results suggest that the new venous catheter with side holes can reduce the infusion pressure by power injection of contrast-enhanced CT and MRI.

Generalized image contrast enhancement technique based on Heinemann contrast discrimination model

NASA Astrophysics Data System (ADS)

Liu, Hong; Nodine, Calvin F.

1994-03-01

This paper presents a generalized image contrast enhancement technique which equalizes perceived brightness based on the Heinemann contrast discrimination model. This is a modified algorithm which presents an improvement over the previous study by Mokrane in its mathematically proven existence of a unique solution and in its easily tunable parameterization. The model uses a log-log representation of contrast luminosity between targets and the surround in a fixed luminosity background setting. The algorithm consists of two nonlinear gray-scale mapping functions which have seven parameters, two of which are adjustable Heinemann constants. Another parameter is the background gray level. The remaining four parameters are nonlinear functions of gray scale distribution of the image, and can be uniquely determined once the previous three are given. Tests have been carried out to examine the effectiveness of the algorithm for increasing the overall contrast of images. It can be demonstrated that the generalized algorithm provides better contrast enhancement than histogram equalization. In fact, the histogram equalization technique is a special case of the proposed mapping.

Optimization of subcutaneous vein contrast enhancement

NASA Astrophysics Data System (ADS)

Zeman, Herbert D.; Lovhoiden, Gunnar; Deshmukh, Harshal

2000-05-01

A technique for enhancing the contrast of subcutaneous veins has been demonstrated. This techniques uses a near IR light source and one or more IR sensitive CCD TV cameras to produce a contrast enhanced image of the subcutaneous veins. This video image of the veins is projected back onto the patient's skin using a n LCD video projector. The use of an IR transmitting filter in front of the video cameras prevents any positive feedback from the visible light from the video projector from causing instabilities in the projected image. The demonstration contrast enhancing illuminator has been tested on adults and children, both Caucasian and African-American, and it enhances veins quite well in all cases. The most difficult cases are those where significant deposits of subcutaneous fat are present which make the veins invisible under normal room illumination. Recent attempts to see through fat using different IR wavelength bands and both linearly and circularly polarized light were unsuccessful. The key to seeing through fat turns out to be a very diffuse source of RI light. Results on adult and pediatric subjects are shown with this new IR light source.

Dose optimization of contrast-enhanced carotid MR angiography.

PubMed

Unterweger, M; Froehlich, J M; Kubik-Huch, R A; Seifert, B; Birrer, M; Huber, T; Otto, R

2005-09-01

The purpose of this work was to compare the diagnostic performance of a single-contrast or a double-contrast dose of carotid contrast-enhanced MR angiography (MRA). One-hundred nineteen patients (mean age 65+/-14.4 years) underwent carotid contrast-enhanced MRA with a standardized protocol (repetition time/echo 3.73 ms/1.38 ms, flip-angle 25 degrees, acquisition-time 19 s, voxel size 1.2 x 1.2 x 0.9 mm3) on a 1.5-T scanner (Sonata, Siemens-Medical-Systems) using a neck phased-array coil. Contrast agent was administered intravenously at a rate of 3.0 ml/s, either as a single dose (n=57; 0.1 mmol/kg body weight) or as a double dose (n=62; 0.2 mmol/kg body weight) of meglumine gadoterate (0.5 M/l), followed by 30 ml saline. Qualitative image analysis was performed on maximum intensity projections using a five-point scale. Signal intensities were measured at three different vascular levels on both sides to assess the contrast-to-noise ratios (CNRs). Image quality was rated as good or excellent in all cases. A double dose did not influence the efficacy of carotid enhancement (CNR single dose 69.12+/-19.8; CNR double dose 70.01+/-20.7; p = 0.81) compared with a single dose. In both dose groups the mean CNRs were inversely related to bodyweight, despite adjusted contrast volumes (p=0.0005). Double-dose contrast-enhanced carotid MRA is not superior to single-dose MRA, as overall diagnostic performance and quantitative contrast enhancement are equal. Being more cost-efficient, a single-dose administration of contrast agent is recommended for MRA of the carotid arteries.

Sequential contrast-enhanced MR imaging of the penis.

PubMed

Kaneko, K; De Mouy, E H; Lee, B E

1994-04-01

To determine the enhancement patterns of the penis at magnetic resonance (MR) imaging. Sequential contrast material-enhanced MR images of the penis in a flaccid state were obtained in 16 volunteers (12 with normal penile function and four with erectile dysfunction). Subjects with normal erectile function showed gradual and centrifugal enhancement of the corpora cavernosa, while those with erectile dysfunction showed poor enhancement with abnormal progression. Sequential contrast-enhanced MR imaging provides additional morphologic information for the evaluation of erectile dysfunction.

Detection of vascularity in wrist tenosynovitis: power doppler ultrasound compared with contrast-enhanced grey-scale ultrasound.

PubMed

Klauser, Andrea S; Franz, Magdalena; Arora, Rohit; Feuchtner, Gudrun M; Gruber, Johann; Schirmer, Michael; Jaschke, Werner R; Gabl, Markus F

2010-01-01

We sought to assess vascularity in wrist tenosynovitis by using power Doppler ultrasound (PDUS) and to compare detection of intra- and peritendinous vascularity with that of contrast-enhanced grey-scale ultrasound (CEUS). Twenty-six tendons of 24 patients (nine men, 15 women; mean age ± SD, 54.4 ± 11.8 years) with a clinical diagnosis of tenosynovitis were examined with B-mode ultrasonography, PDUS, and CEUS by using a second-generation contrast agent, SonoVue (Bracco Diagnostics, Milan, Italy) and a low-mechanical-index ultrasound technique. Thickness of synovitis, extent of vascularized pannus, intensity of peritendinous vascularisation, and detection of intratendinous vessels was incorporated in a 3-score grading system (grade 0 to 2). Interobserver variability was calculated. With CEUS, a significantly greater extent of vascularity could be detected than by using PDUS (P < 0.001). In terms of peri- and intratendinous vessels, CEUS was significantly more sensitive in the detection of vascularization compared with PDUS (P < 0.001). No significant correlation between synovial thickening and extent of vascularity could be found (P = 0.089 to 0.097). Interobserver reliability was calculated to be excellent when evaluating the grading score (κ = 0.811 to 1.00). CEUS is a promising tool to detect tendon vascularity with higher sensitivity than PDUS by improved detection of intra- and peritendinous vascularity.

CO2 microbubble contrast enhancement in x-ray angiography.

PubMed

Kariya, S; Komemushi, A; Nakatani, M; Yoshida, R; Sawada, S; Tanigawa, N

2013-04-01

To demonstrate that carbon dioxide (CO2) microbubble contrast enhancement depicts blood vessels when used for x-ray examinations. Microbubbles were generated by cavitation of physiological saline to which CO2 gas had been added using an ejector-type microbubble generator. The input pressure values for CO2 gas and physiological saline that produced a large quantity of CO2 microbubbles were obtained in a phantom. In an animal study, angiography was performed in three swine using three types of contrast: CO2 microbubbles, conventional CO2 gas, and iodinated contrast medium. For CO2 microbubble contrast enhancement, physiological saline, and CO2 gas were supplied at the input pressures calculated in the phantom experiment. Regions of interest were set in the abdominal aorta, external iliac arteries, and background. The difference in digital values between each artery and the background was calculated. The input pressures obtained in the phantom experiment were 0.16 MPa for physiological saline and 0.5 MPa for CO2 gas, with physiological saline input volume being 8.1 ml/s. Three interventional radiologists all evaluated the depictions of all arteries as "present" in the CO2 microbubble contrast enhancement, conventional CO2 contrast enhancement, and iodinated contrast enhancement performed in three swine. Digital values for all vessels with microbubble CO2 contrast enhancement were higher than background values. In x-ray angiography, blood vessels can be depicted by CO2 microbubble contrast enhancement, in which a large quantity of CO2 microbubbles is generated within blood vessels. Copyright © 2012 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Journal Club: Comparison of assessment of preoperative pulmonary vasculature in patients with non-small cell lung cancer by non-contrast- and 4D contrast-enhanced 3-T MR angiography and contrast-enhanced 64-MDCT.

PubMed

Ohno, Yoshiharu; Nishio, Mizuho; Koyama, Hisanobu; Yoshikawa, Takeshi; Matsumoto, Sumiaki; Seki, Shinichiro; Sugimura, Kazuro

2014-03-01

The purpose of this article is to prospectively and directly compare the capabilities of non-contrast-enhanced MR angiography (MRA), 4D contrast-enhanced MRA, and contrast-enhanced MDCT for assessing pulmonary vasculature in patients with non-small cell lung cancer (NSCLC) before surgical treatment. A total of 77 consecutive patients (41 men and 36 women; mean age, 71 years) with pathologically proven and clinically assessed stage I NSCLC underwent thin-section contrast-enhanced MDCT, non-contrast-enhanced and contrast-enhanced MRA, and surgical treatment. The capability for anomaly assessment of the three methods was independently evaluated by two reviewers using a 5-point visual scoring system, and final assessment for each patient was made by consensus of the two readers. Interobserver agreement for pulmonary arterial and venous assessment was evaluated with the kappa statistic. Then, sensitivity, specificity, and accuracy for the detection of anomalies were directly compared among the three methods by use of the McNemar test. Interobserver agreement for pulmonary artery and vein assessment was substantial or almost perfect (κ=0.72-0.86). For pulmonary arterial and venous variation assessment, there were no significant differences in sensitivity, specificity, and accuracy among non-contrast-enhanced MRA (pulmonary arteries: sensitivity, 77.1%; specificity, 97.4%; accuracy, 87.7%; pulmonary veins: sensitivity, 50%; specificity, 98.5%; accuracy, 93.2%), 4D contrast-enhanced MRA (pulmonary arteries: sensitivity, 77.1%; specificity, 97.4%; accuracy, 87.7%; pulmonary veins: sensitivity, 62.5%; specificity, 100.0%; accuracy, 95.9%), and thin-section contrast-enhanced MDCT (pulmonary arteries: sensitivity, 91.4%; specificity, 89.5%; accuracy, 90.4%; pulmonary veins: sensitivity, 50%; specificity, 100.0%; accuracy, 95.9%) (p>0.05). Pulmonary vascular assessment of patients with NSCLC before surgical resection by non-contrast-enhanced MRA can be considered equivalent to

Local adaptive contrast enhancement for color images

NASA Astrophysics Data System (ADS)

Dijk, Judith; den Hollander, Richard J. M.; Schavemaker, John G. M.; Schutte, Klamer

2007-04-01

A camera or display usually has a smaller dynamic range than the human eye. For this reason, objects that can be detected by the naked eye may not be visible in recorded images. Lighting is here an important factor; improper local lighting impairs visibility of details or even entire objects. When a human is observing a scene with different kinds of lighting, such as shadows, he will need to see details in both the dark and light parts of the scene. For grey value images such as IR imagery, algorithms have been developed in which the local contrast of the image is enhanced using local adaptive techniques. In this paper, we present how such algorithms can be adapted so that details in color images are enhanced while color information is retained. We propose to apply the contrast enhancement on color images by applying a grey value contrast enhancement algorithm to the luminance channel of the color signal. The color coordinates of the signal will remain the same. Care is taken that the saturation change is not too high. Gamut mapping is performed so that the output can be displayed on a monitor. The proposed technique can for instance be used by operators monitoring movements of people in order to detect suspicious behavior. To do this effectively, specific individuals should both be easy to recognize and track. This requires optimal local contrast, and is sometimes much helped by color when tracking a person with colored clothes. In such applications, enhanced local contrast in color images leads to more effective monitoring.

5-Aminolevulinic Acid Induced Fluorescence Is a Powerful Intraoperative Marker for Precise Histopathological Grading of Gliomas with Non-Significant Contrast-Enhancement

PubMed Central

Widhalm, Georg; Kiesel, Barbara; Woehrer, Adelheid; Traub-Weidinger, Tatjana; Preusser, Matthias; Marosi, Christine; Prayer, Daniela; Hainfellner, Johannes A.; Knosp, Engelbert; Wolfsberger, Stefan

2013-01-01

Background Intraoperative identification of anaplastic foci in diffusely infiltrating gliomas (DIG) with non-significant contrast-enhancement on MRI is indispensible to avoid histopathological undergrading and subsequent treatment failure. Recently, we found that 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PpIX) fluorescence can visualize areas with increased proliferative and metabolic activity in such gliomas intraoperatively. As treatment of DIG is predominantely based on histopathological World Health Organisation (WHO) parameters, we analyzed whether PpIX fluorescence can detect anaplastic foci according to these criteria. Methods We prospectively included DIG patients with non-significant contrast-enhancement that received 5-ALA prior to resection. Intraoperatively, multiple samples from PpIX positive and negative intratumoral areas were collected using a modified neurosurgical microscope. In all samples, histopathological WHO criteria and proliferation rate were assessed and correlated to the PpIX fluorescence status. Results A total of 215 tumor specimens were collected in 59 patients. Of 26 WHO grade III gliomas, 23 cases (85%) showed focal PpIX fluorescence, whereas 29 (91%) of 33 WHO grade II gliomas were PpIX negative. In intratumoral areas with focal PpIX fluorescence, mitotic rate, cell density, nuclear pleomorphism, and proliferation rate were significantly higher than in non-fluorescing areas. The positive predictive value of focal PpIX fluorescence for WHO grade III histology was 85%. Conclusions Our study indicates that 5-ALA induced PpIX fluorescence is a powerful marker for intraoperative identification of anaplastic foci according to the histopathological WHO criteria in DIG with non-significant contrast-enhancement. Therefore, application of 5-ALA optimizes tissue sampling for precise histopathological diagnosis independent of brain-shift. PMID:24204718

5-Aminolevulinic acid induced fluorescence is a powerful intraoperative marker for precise histopathological grading of gliomas with non-significant contrast-enhancement.

PubMed

Widhalm, Georg; Kiesel, Barbara; Woehrer, Adelheid; Traub-Weidinger, Tatjana; Preusser, Matthias; Marosi, Christine; Prayer, Daniela; Hainfellner, Johannes A; Knosp, Engelbert; Wolfsberger, Stefan

2013-01-01

Intraoperative identification of anaplastic foci in diffusely infiltrating gliomas (DIG) with non-significant contrast-enhancement on MRI is indispensible to avoid histopathological undergrading and subsequent treatment failure. Recently, we found that 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PpIX) fluorescence can visualize areas with increased proliferative and metabolic activity in such gliomas intraoperatively. As treatment of DIG is predominantely based on histopathological World Health Organisation (WHO) parameters, we analyzed whether PpIX fluorescence can detect anaplastic foci according to these criteria. We prospectively included DIG patients with non-significant contrast-enhancement that received 5-ALA prior to resection. Intraoperatively, multiple samples from PpIX positive and negative intratumoral areas were collected using a modified neurosurgical microscope. In all samples, histopathological WHO criteria and proliferation rate were assessed and correlated to the PpIX fluorescence status. A total of 215 tumor specimens were collected in 59 patients. Of 26 WHO grade III gliomas, 23 cases (85%) showed focal PpIX fluorescence, whereas 29 (91%) of 33 WHO grade II gliomas were PpIX negative. In intratumoral areas with focal PpIX fluorescence, mitotic rate, cell density, nuclear pleomorphism, and proliferation rate were significantly higher than in non-fluorescing areas. The positive predictive value of focal PpIX fluorescence for WHO grade III histology was 85%. Our study indicates that 5-ALA induced PpIX fluorescence is a powerful marker for intraoperative identification of anaplastic foci according to the histopathological WHO criteria in DIG with non-significant contrast-enhancement. Therefore, application of 5-ALA optimizes tissue sampling for precise histopathological diagnosis independent of brain-shift.

Assessment of inflammatory activity in Crohn's disease by means of dynamic contrast-enhanced MRI.

PubMed

Pupillo, V A; Di Cesare, E; Frieri, G; Limbucci, N; Tanga, M; Masciocchi, C

2007-09-01

Our aim was to perform a dynamic study of contrast enhancement of the intestinal wall in patients with Crohn's disease to quantitatively assess local inflammatory activity. We studied a population of 50 patients with histologically proven Crohn's disease. Magnetic resonance imaging (MRI) was performed using a 1.5-T magnet with a phased-array coil and acquisition of T2-weighted single-shot fast spin echo (SSFSE) half Fourier sequences before intravenous administration of gadolinium, and T1-weighted fast spoiled gradient (FSPGR) fat-saturated sequences before and after contrast administration. Before the examination, patents received oral polyethylene glycol (PEG) (1,000 ml for adults; 10 ml/Kg of body weight for children). Regions of interest (ROI) were placed on the normal and diseased intestinal wall to assess signal intensity and rate of increase in contrast enhancement over time. Data were compared with the Crohn's Disease Activity Index (CDAI). The diseased bowel wall showed early and intense uptake of contrast that increases over time until a plateau is reached. In patients in the remission phase after treatment, signal intensity was only slightly higher in diseased bowel loops than in healthy loops. There was a significant correlation between the peak of contrast uptake and CDAI. Dynamic MRI is a good technique for quantifying local inflammatory activity of bowel wall in patients with Crohn's disease.

Contrast enhancement of mail piece images

NASA Astrophysics Data System (ADS)

Shin, Yong-Chul; Sridhar, Ramalingam; Demjanenko, Victor; Palumbo, Paul W.; Hull, Jonathan J.

1992-08-01

A New approach to contrast enhancement of mail piece images is presented. The contrast enhancement is used as a preprocessing step in the real-time address block location (RT-ABL) system. The RT-ABL system processes a stream of mail piece images and locates destination address blocks. Most of the mail pieces (classified into letters) show high contrast between background and foreground. As an extreme case, however, the seasonal greeting cards usually use colored envelopes which results in reduced contrast osured by an error rate by using a linear distributed associative memory (DAM). The DAM is trained to recognize the spectra of three classes of images: with high, medium, and low OCR error rates. The DAM is not forced to make a classification every time. It is allowed to reject as unknown a spectrum presented that does not closely resemble any that has been stored in the DAM. The DAM was fairly accurate with noisy images but conservative (i.e., rejected several text images as unknowns) when there was little ground and foreground degradations without affecting the nondegraded images. This approach provides local enhancement which adapts to local features. In order to simplify the computation of A and (sigma) , dynamic programming technique is used. Implementation details, performance, and the results on test images are presented in this paper.

Contrast Enhanced Spectral Mammography: A Review.

PubMed

Patel, Bhavika K; Lobbes, M B I; Lewin, John

2018-02-01

Contrast-enhanced spectral mammography (CESM) provides low-energy 2D mammographic images comparable to standard digital mammography and a post-contrast recombined image to assess tumor neovascularity similar to magnetic resonance imaging (MRI). The utilization of CESM in the United States is currently low but could increase rapidly given many potential indications for clinical use. This article discusses historical background and literature review of indications and diagnostic accuracy of CESM to date. CESM is a growing technique for breast cancer detection and diagnosis that has levels of sensitivity and specificity on par with contrast-enhanced breast MRI. Because of its similar performance and ease of implementation, CESM is being adopted for multiple indications previously reserved for MRI, such as problem-solving, disease extent in newly diagnosed patients, and evaluating the treatment response of neoadjuvant chemotherapy. Copyright © 2018 Elsevier Inc. All rights reserved.

Dynamic contrast-enhanced optical imaging of in vivo organ function

NASA Astrophysics Data System (ADS)

Amoozegar, Cyrus B.; Wang, Tracy; Bouchard, Matthew B.; McCaslin, Addason F. H.; Blaner, William S.; Levenson, Richard M.; Hillman, Elizabeth M. C.

2012-09-01

Conventional approaches to optical small animal molecular imaging suffer from poor resolution, limited sensitivity, and unreliable quantitation, often reducing their utility in practice. We previously demonstrated that the in vivo dynamics of an injected contrast agent could be exploited to provide high-contrast anatomical registration, owing to the temporal differences in each organ's response to the circulating fluorophore. This study extends this approach to explore whether dynamic contrast-enhanced optical imaging (DyCE) can allow noninvasive, in vivo assessment of organ function by quantifying the differing cellular uptake or wash-out dynamics of an agent in healthy and damaged organs. Specifically, we used DyCE to visualize and measure the organ-specific uptake dynamics of indocyanine green before and after induction of transient liver damage. DyCE imaging was performed longitudinally over nine days, and blood samples collected at each imaging session were analyzed for alanine aminotransferase (ALT), a liver enzyme assessed clinically as a measure of liver damage. We show that changes in DyCE-derived dynamics of liver and kidney dye uptake caused by liver damage correlate linearly with ALT concentrations, with an r2 value of 0.91. Our results demonstrate that DyCE can provide quantitative, in vivo, longitudinal measures of organ function with inexpensive and simple data acquisition.

Design and validation of a mathematical breast phantom for contrast-enhanced digital mammography

NASA Astrophysics Data System (ADS)

Hill, Melissa L.; Mainprize, James G.; Jong, Roberta A.; Yaffe, Martin J.

2011-03-01

In contrast-enhanced digital mammography (CEDM) an iodinated contrast agent is employed to increase lesion contrast and to provide tissue functional information. Here, we present the details of a software phantom that can be used as a tool for the simulation of CEDM images, and compare the degree of anatomic noise present in images simulated using the phantom to that associated with breast parenchyma in clinical CEDM images. Such a phantom could be useful for multiparametric investigations including characterization of CEDM imaging performance and system optimization. The phantom has a realistic mammographic appearance based on a clustered lumpy background and models contrast agent uptake according to breast tissue physiology. Fifty unique phantoms were generated and used to simulate regions of interest (ROI) of pre-contrast images and logarithmically subtracted CEDM images using monoenergetic ray tracing. Power law exponents, β, were used as a measure of anatomic noise and were determined using a linear least-squares fit to log-log plots of the square of the modulus of radially averaged image power spectra versus spatial frequency. The power spectra for ROI selected from regions of normal parenchyma in 10 pairs of clinical CEDM pre-contrast and subtracted images were also measured for comparison with the simulated images. There was good agreement between the measured β in the simulated CEDM images and the clinical images. The values of β were consistently lower for the logarithmically subtracted CEDM images compared to the pre-contrast images, indicating that the subtraction process reduced anatomical noise.

Effect of contrast enhancement on measurement of carotid artery intimal medial thickness.

PubMed

Macioch, James E; Katsamakis, C Dean; Robin, Jason; Liebson, Philip R; Meyer, Peter M; Geohas, Chris; Raichlen, Joel S; Davidson, Michael H; Feinstein, Steven B

2004-02-01

Previous studies have used standard B-mode ultrasound to quantify the aggregate mean intimal medial thickness (IMT) of the near and far wall of the common carotid artery (CCA). Many investigators have had difficulty in accurately evaluating the near wall IMT secondary to difficulty in discerning the vessel lumen and intima. The purpose of this study is to determine the effect of contrast enhanced ultrasound on IMT measurement when compared with non-enhanced images. Twenty-six patients who had standard carotid ultrasounds completed over a 6-month period were evaluated, with 24 imaged by the same sonographer. Five to six measurements of the near and far walls were obtained over a 1 cm distance, beginning and ending 0.5 cm and 1.5 cm proximal to the carotid bifurcation. The measurements were made with and without the contrast agent Optison (perflutren protein type-A microspheres), which was given as an i.v. bolus (0.5-0.7 cc). Of those imaged by the same sonographer, 40 carotid arteries were examined and a total of 867 measurements were obtained. A total of 10% of the carotid ultrasounds were restudied approximately 1 month after the initial interpretation to assess observer accuracy. The near wall CCA mean (SD) IMT was 0.075 (0.019) cm for left with contrast versus 0.067 (0.023) cm for left without contrast and 0.089 (0.024) cm for right with versus 0.071 (0.022) cm for right without, p < or = 0.0001 both sides. For the far wall of the CCA, the mean (SD) IMT comparison was 0.075 (0.021) cm for left with versus 0.070 (0.016) cm for left without, p = 0.005, and 0.070 (0.023) cm for right with versus 0.070 (0.016) cm for right without, p = 0.68. In conclusion, contrast-enhanced IMT measurement showed a highly statistically significant difference in near carotid wall thickness determinations versus non-contrast values. The thicker measurement is in agreement with previously reported data showing that non-contrast images underestimated near wall common carotid IMT in

Generalized image contrast enhancement technique based on the Heinemann contrast discrimination model

NASA Astrophysics Data System (ADS)

Liu, Hong; Nodine, Calvin F.

1996-07-01

This paper presents a generalized image contrast enhancement technique, which equalizes the perceived brightness distribution based on the Heinemann contrast discrimination model. It is based on the mathematically proven existence of a unique solution to a nonlinear equation, and is formulated with easily tunable parameters. The model uses a two-step log-log representation of luminance contrast between targets and surround in a luminous background setting. The algorithm consists of two nonlinear gray scale mapping functions that have seven parameters, two of which are adjustable Heinemann constants. Another parameter is the background gray level. The remaining four parameters are nonlinear functions of the gray-level distribution of the given image, and can be uniquely determined once the previous three are set. Tests have been carried out to demonstrate the effectiveness of the algorithm for increasing the overall contrast of radiology images. The traditional histogram equalization can be reinterpreted as an image enhancement technique based on the knowledge of human contrast perception. In fact, it is a special case of the proposed algorithm.

Comparison of Power Versus Manual Injection in Bolus Shape and Image Quality on Contrast-Enhanced Magnetic Resonance Angiography: An Experimental Study in a Swine Model.

PubMed

Tsuboyama, Takahiro; Jost, Gregor; Pietsch, Hubertus; Tomiyama, Noriyuki

2017-09-01

The aim of this study was to compare power versus manual injection in bolus shape and image quality on contrast-enhanced magnetic resonance angiography (CE-MRA). Three types of CE-MRA (head-neck 3-dimensional [3D] MRA with a test-bolus technique, thoracic-abdominal 3D MRA with a bolus-tracking technique, and thoracic-abdominal time-resolved 4-dimensional [4D] MRA) were performed after power and manual injection of gadobutrol (0.1 mmol/kg) at 2 mL/s in 12 pigs (6 sets of power and manual injections for each type of CE-MRA). For the quantitative analysis, the signal-to-noise ratio was measured on ascending aorta, descending aorta, brachiocephalic trunk, common carotid artery, and external carotid artery on the 6 sets of head-neck 3D MRA, and on ascending aorta, descending aorta, brachiocephalic trunk, abdominal aorta, celiac trunk, and renal artery on the 6 sets of thoracic-abdominal 3D MRA. Bolus shapes were evaluated on the 6 sets each of test-bolus scans and 4D MRA. For the qualitative analysis, arterial enhancement, superimposition of nontargeted enhancement, and overall image quality were evaluated on 3D MRA. Visibility of bolus transition was assessed on 4D MRA. Intraindividual comparison between power and manual injection was made by paired t test, Wilcoxon rank sum test, and analysis of variance by ranks. Signal-to-noise ratio on 3D MRA was statistically higher with power injection than with manual injection (P < 0.001). Bolus shapes (test-bolus, 4D MRA) were represented by a characteristic standard bolus curve (sharp first-pass peak followed by a gentle recirculation peak) in all the 12 scans with power injection, but only in 1 of the 12 scans with manual injection. Standard deviations of time-to-peak enhancement were smaller in power injection than in manual injection. Qualitatively, although both injection methods achieved diagnostic quality on 3D MRA, power injection exhibited significantly higher image quality than manual injection (P = 0.001) due to

Syringeless power injector versus dual-syringe power injector: economic evaluation of user performance, the impact on contrast enhanced computed tomography (CECT) workflow exams, and hospital costs.

PubMed

Colombo, Giorgio L; Andreis, Ivo A Bergamo; Di Matteo, Sergio; Bruno, Giacomo M; Mondellini, Claudio

2013-01-01

The utilization of diagnostic imaging has substantially increased over the past decade in Europe and North America and continues to grow worldwide. The purpose of this study was to develop an economic evaluation of a syringeless power injector (PI) versus a dual-syringe PI for contrast enhanced computed tomography (CECT) in a hospital setting. Patients (n=2379) were enrolled at the Legnano Hospital between November 2012 and January 2013. They had been referred to the hospital for a CECT analysis and were randomized into two groups. The first group was examined with a 256-MDCT (MultiDetector Computed Tomography) scanner using a syringeless power injector, while the other group was examined with a 64-MDCT scanner using a dual-syringe. Data on the operators' time required in the patient analysis steps as well as on the quantity of consumable materials used were collected. The radiologic technologists' satisfaction with the use of the PIs was rated on a 10-point scale. A budget impact analysis and sensitivity analysis were performed under the base-case scenario. A total of 1,040 patients were examined using the syringeless system, and 1,339 with the dual-syringe system; the CECT examination quality was comparable for both PI systems. Equipment preparation time and releasing time per examination for syringeless PIs versus dual-syringe PIs were 100±30 versus 180±30 seconds and 90±30 and 140±20 seconds, respectively. On average, 10±3 mL of contrast media (CM) wastage per examination was observed with the dual-syringe PI and 0±1 mL with the syringeless PI. Technologists had higher satisfaction with the syringeless PI than with the dual-syringe system (8.8 versus 8.0). The syringeless PI allows a saving of about €6.18 per patient, both due to the lower cost of the devices and to the better performance of the syringeless system. The univariate sensitivity analysis carried out on the base-case results within the standard deviation range confirmed the saving generated

Contrast-enhanced peripheral MRA: technique and contrast agents.

PubMed

Nielsen, Yousef W; Thomsen, Henrik S

2012-09-01

In the last decade contrast-enhanced magnetic resonance angiography (CE-MRA) has gained wide acceptance as a valuable tool in the diagnostic work-up of patients with peripheral arterial disease. This review presents current concepts in peripheral CE-MRA with emphasis on MRI technique and contrast agents. Peripheral CE-MRA is defined as an MR angiogram of the arteries from the aortic bifurcation to the feet. Advantages of CE-MRA include minimal invasiveness and lack of ionizing radiation. The basic technique employed for peripheral CE-MRA is the bolus-chase method. With this method a paramagnetic MRI contrast agent is injected intravenously and T1-weighted images are acquired in the subsequent arterial first-pass phase. In order to achieve high quality MR angiograms without interfering venous contamination or artifacts, a number of factors need to be taken into account. This includes magnetic field strength of the MRI system, receiver coil configuration, use of parallel imaging, contrast bolus timing technique, and k-space filling strategies. Furthermore, it is possible to optimize peripheral CE-MRA using venous compression techniques, hybrid scan protocols, time-resolved imaging, and steady-state MRA. Gadolinium(Gd)-based contrast agents are used for CE-MRA of the peripheral arteries. Extracellular Gd agents have a pharmacokinetic profile similar to iodinated contrast media. Accordingly, these agents are employed for first-pass MRA. Blood-pool Gd-based agents are characterized by prolonged intravascular stay, due to macromolecular structure or protein binding. These agents can be used for first-pass, as well as steady-state MRA. Some Gd-based contrast agents with low thermodynamic stability have been linked to development of nephrogenic systemic fibrosis in patients with severe renal insufficiency. Using optimized technique and a stable MRI contrast agent, peripheral CE-MRA is a safe procedure with diagnostic accuracy close to that of conventional catheter X

Solar-Powered Plasmon-Enhanced Heterogeneous Catalysis

NASA Astrophysics Data System (ADS)

Naldoni, Alberto; Riboni, Francesca; Guler, Urcan; Boltasseva, Alexandra; Shalaev, Vladimir M.; Kildishev, Alexander V.

2016-06-01

Photocatalysis uses semiconductors to convert sunlight into chemical energy. Recent reports have shown that plasmonic nanostructures can be used to extend semiconductor light absorption or to drive direct photocatalysis with visible light at their surface. In this review, we discuss the fundamental decay pathway of localized surface plasmons in the context of driving solar-powered chemical reactions. We also review different nanophotonic approaches demonstrated for increasing solar-to-hydrogen conversion in photoelectrochemical water splitting, including experimental observations of enhanced reaction selectivity for reactions occurring at the metalsemiconductor interface. The enhanced reaction selectivity is highly dependent on the morphology, electronic properties, and spatial arrangement of composite nanostructures and their elements. In addition, we report on the particular features of photocatalytic reactions evolving at plasmonic metal surfaces and discuss the possibility of manipulating the reaction selectivity through the activation of targeted molecular bonds. Finally, using solar-to-hydrogen conversion techniques as an example, we quantify the efficacy metrics achievable in plasmon-driven photoelectrochemical systems and highlight some of the new directions that could lead to the practical implementation of solar-powered plasmon-based catalytic devices.

Potential Cost Savings of Contrast-Enhanced Digital Mammography.

PubMed

Patel, Bhavika K; Gray, Richard J; Pockaj, Barbara A

2017-06-01

The purpose of this article is to discuss whether the sensitivity and specificity of contrast-enhanced digital mammography (CEDM) render it a viable diagnostic alternative to breast MRI. That CEDM couples low-energy images (comparable to the diagnostic quality of standard mammography) and subtracted contrast-enhanced mammograms make it a cost-effective modality and a realistic substitute for the more costly breast MRI.

Visual performance-based image enhancement methodology: an investigation of contrast enhancement algorithms

NASA Astrophysics Data System (ADS)

Neriani, Kelly E.; Herbranson, Travis J.; Reis, George A.; Pinkus, Alan R.; Goodyear, Charles D.

2006-05-01

While vast numbers of image enhancing algorithms have already been developed, the majority of these algorithms have not been assessed in terms of their visual performance-enhancing effects using militarily relevant scenarios. The goal of this research was to apply a visual performance-based assessment methodology to evaluate six algorithms that were specifically designed to enhance the contrast of digital images. The image enhancing algorithms used in this study included three different histogram equalization algorithms, the Autolevels function, the Recursive Rational Filter technique described in Marsi, Ramponi, and Carrato1 and the multiscale Retinex algorithm described in Rahman, Jobson and Woodell2. The methodology used in the assessment has been developed to acquire objective human visual performance data as a means of evaluating the contrast enhancement algorithms. Objective performance metrics, response time and error rate, were used to compare algorithm enhanced images versus two baseline conditions, original non-enhanced images and contrast-degraded images. Observers completed a visual search task using a spatial-forcedchoice paradigm. Observers searched images for a target (a military vehicle) hidden among foliage and then indicated in which quadrant of the screen the target was located. Response time and percent correct were measured for each observer. Results of the study and future directions are discussed.

Contrast-enhanced spectral mammography (CESM) and contrast enhanced MRI (CEMRI): Patient preferences and tolerance.

PubMed

Hobbs, Max M; Taylor, Donna B; Buzynski, Sebastian; Peake, Rachel E

2015-06-01

Contrast-enhanced spectral mammography (CESM) may have similar diagnostic performance to Contrast-enhanced MRI (CEMRI) in the diagnosis and staging of breast cancer. To date, research has focused exclusively on diagnostic performance when comparing these two techniques. Patient experience is also an important factor when comparing and deciding on which of these modalities is preferable. The aim of this study is to compare patient experience of CESM against CEMRI during preoperative breast cancer staging. Forty-nine participants who underwent both CESM and CEMRI, as part of a larger trial, completed a Likert questionnaire about their preference for each modality according to the following criteria: comfort of breast compression, comfort of intravenous (IV) contrast injection, anxiety and overall preference. Participants also reported reasons for preferring one modality to the other. Quantitative data were analysed using a Wilcoxon sign-rank test and chi-squared test. Qualitative data are reported descriptively. A significantly higher overall preference towards CESM was demonstrated (n = 49, P < 0.001), with faster procedure time, greater comfort and lower noise level cited as the commonest reasons. Participants also reported significantly lower rates of anxiety during CESM compared with CEMRI (n = 36, P = 0.009). A significantly higher rate of comfort was reported during CEMRI for measures of breast compression (n = 49, P = 0.001) and the sensation of IV contrast injection (n = 49, P = 0.003). Our data suggest that overall, patients prefer the experience of CESM to CEMRI, adding support for the role of CESM as a possible alternative to CEMRI for breast cancer staging. © 2015 The Royal Australian and New Zealand College of Radiologists.

Topological study of nanomaterials using surface-enhanced ellipsometric contrast microscopy (SEEC)

NASA Astrophysics Data System (ADS)

Muckenhirn, Sylvain

2016-03-01

Innovations in nanotechnology are empowering scientists to deepen their understanding of physical, chemical and biological mechanisms. Powerful and precise characterization systems are essential to meet researchers' requirements. SEEC (Surface Enhanced Ellipsometric Contrast) microscopy is an innovative advanced optical technique based on ellipsometric and interference fringes of Fizeau principles. This technique offers live and label-free topographic imaging of organic, inorganic and biological samples with high Z resolution (down to 0.1nm thickness), and enhanced X-Y detection limit (down to 1.5nm width). This technique has been successfully applied to the study of nanometric films and structures, biological layers, and nano-objects. We applied SEEC technology to different applications explored below.

Enhancement of multispectral thermal infrared images - Decorrelation contrast stretching

NASA Technical Reports Server (NTRS)

Gillespie, Alan R.

1992-01-01

Decorrelation contrast stretching is an effective method for displaying information from multispectral thermal infrared (TIR) images. The technique involves transformation of the data to principle components ('decorrelation'), independent contrast 'stretching' of data from the new 'decorrelated' image bands, and retransformation of the stretched data back to the approximate original axes, based on the inverse of the principle component rotation. The enhancement is robust in that colors of the same scene components are similar in enhanced images of similar scenes, or the same scene imaged at different times. Decorrelation contrast stretching is reviewed in the context of other enhancements applied to TIR images.

Contrast-dependent saturation adjustment for outdoor image enhancement.

PubMed

Wang, Shuhang; Cho, Woon; Jang, Jinbeum; Abidi, Mongi A; Paik, Joonki

2017-01-01

Outdoor images captured in bad-weather conditions usually have poor intensity contrast and color saturation since the light arriving at the camera is severely scattered or attenuated. The task of improving image quality in poor conditions remains a challenge. Existing methods of image quality improvement are usually effective for a small group of images but often fail to produce satisfactory results for a broader variety of images. In this paper, we propose an image enhancement method, which makes it applicable to enhance outdoor images by using content-adaptive contrast improvement as well as contrast-dependent saturation adjustment. The main contribution of this work is twofold: (1) we propose the content-adaptive histogram equalization based on the human visual system to improve the intensity contrast; and (2) we introduce a simple yet effective prior for adjusting the color saturation depending on the intensity contrast. The proposed method is tested with different kinds of images, compared with eight state-of-the-art methods: four enhancement methods and four haze removal methods. Experimental results show the proposed method can more effectively improve the visibility and preserve the naturalness of the images, as opposed to the compared methods.

Medial tibial pain: a dynamic contrast-enhanced MRI study.

PubMed

Mattila, K T; Komu, M E; Dahlström, S; Koskinen, S K; Heikkilä, J

1999-09-01

The purpose of this study was to compare the sensitivity of different magnetic resonance imaging (MRI) sequences to depict periosteal edema in patients with medial tibial pain. Additionally, we evaluated the ability of dynamic contrast-enhanced imaging (DCES) to depict possible temporal alterations in muscular perfusion within compartments of the leg. Fifteen patients with medial tibial pain were examined with MRI. T1-, T2-weighted, proton density axial images and dynamic and static phase post-contrast images were compared in ability to depict periosteal edema. STIR was used in seven cases to depict bone marrow edema. Images were analyzed to detect signs of compartment edema. Region-of-interest measurements in compartments were performed during DCES and compared with controls. In detecting periosteal edema, post-contrast T1-weighted images were better than spin echo T2-weighted and proton density images or STIR images, but STIR depicted the bone marrow edema best. DCES best demonstrated the gradually enhancing periostitis. Four subjects with severe periosteal edema had visually detectable pathologic enhancement during DCES in the deep posterior compartment of the leg. Percentage enhancement in the deep posterior compartment of the leg was greater in patients than in controls. The fast enhancement phase in the deep posterior compartment began slightly slower in patients than in controls, but it continued longer. We believe that periosteal edema in bone stress reaction can cause impairment of venous flow in the deep posterior compartment. MRI can depict both these conditions. In patients with medial tibial pain, MR imaging protocol should include axial STIR images (to depict bone pathology) with T1-weighted axial pre and post-contrast images, and dynamic contrast enhanced imaging to show periosteal edema and abnormal contrast enhancement within a compartment.

Comparative analysis of renal flow using contrast power Doppler and gray-scale ultrasound

NASA Astrophysics Data System (ADS)

Sehgal, Chandra M.; Arger, Peter H.; Bovee, Kenneth C.; Pugh, Charles; Kirchhofer, Justin I.

1997-05-01

Our previous studies have shown that renal perfusion can be visualized by imaging the transit of a contrast agent through the parenchyma of the organ using gray scale (GS) and power Doppler (PD) ultrasound.However, the relative merits and the sensitivities of the two imaging methods are not known. This study compares the effectiveness of the two modes in visualizing kidney perfusion at the clinical dose of contrast agents. GS and PD images of the dog kidneys were recorded using a clinical ultrasound scanner at 4-7 MHz. A fixed longitudinal plane of the kidney was imaged by mounting the transducer on the animal with a specially designed holder. A dose of 0.1 m1/kg of Echogen was injected intravenously and GS and PD images were recorded simultaneously on two separate time-encoded video tapes during the passage of the contrast agent through the kidneys. The enhancement of GS and PD images was assessed qualitatively by three radiologists. The quantitative assessment was made by measuring the regional and global enhancements of digitized B-scan and PS images. Regional measurements were made by comparing brightness of the post contrast images with that of a pre-contrast reference image pixel by pixel. Student t-test was used to determine the statistical significance of the change. The regions representing statistically significant differences were encoded on the image in color with brightness proportional to the magnitude of change. The regions with no significant change were represented in GS. This generated a series of new images, referred to as StatMap, with color representing regions of perfusion. Changes in power Doppler images were visually detectable with high confidence in all five dogs by al three radiologists. There was no perceptible changes in B-scans. Computer analysis of PD images yielded characteristic indicator dilution curves in all five dogs with an initial rise time of 2-5 sec and a peak at 7-20 sec. The enhancement in PD lasted for 97-400 seconds. The

Assessment of mass detection performance in contrast enhanced digital mammography

NASA Astrophysics Data System (ADS)

Carton, Ann-Katherine; de Carvalho, Pablo M.; Li, Zhijin; Dromain, Clarisse; Muller, Serge

2015-03-01

We address the detectability of contrast-agent enhancing masses for contrast-agent enhanced spectral mammography (CESM), a dual-energy technique providing functional projection images of breast tissue perfusion and vascularity using simulated CESM images. First, the realism of simulated CESM images from anthropomorphic breast software phantoms generated with a software X-ray imaging platform was validated. Breast texture was characterized by power-law coefficients calculated in data sets of real clinical and simulated images. We also performed a 2-alternative forced choice (2-AFC) psychophysical experiment whereby simulated and real images were presented side-by-side to an experienced radiologist to test if real images could be distinguished from the simulated images. It was found that texture in our simulated CESM images has a fairly realistic appearance. Next, the relative performance of human readers and previously developed mathematical observers was assessed for the detection of iodine-enhancing mass lesions containing different contrast agent concentrations. A four alternative-forced-choice (4 AFC) task was designed; the task for the model and human observer was to detect which one of the four simulated DE recombined images contained an iodineenhancing mass. Our results showed that the NPW and NPWE models largely outperform human performance. After introduction of an internal noise component, both observers approached human performance. The CHO observer performs slightly worse than the average human observer. There is still work to be done in improving model observers as predictors of human-observer performance. Larger trials could also improve our test statistics. We hope that in the future, this framework of software breast phantoms, virtual image acquisition and processing, and mathematical observers can be beneficial to optimize CESM imaging techniques.

Automatic segmentation and quantification of the cardiac structures from non-contrast-enhanced cardiac CT scans

NASA Astrophysics Data System (ADS)

Shahzad, Rahil; Bos, Daniel; Budde, Ricardo P. J.; Pellikaan, Karlijn; Niessen, Wiro J.; van der Lugt, Aad; van Walsum, Theo

2017-05-01

Early structural changes to the heart, including the chambers and the coronary arteries, provide important information on pre-clinical heart disease like cardiac failure. Currently, contrast-enhanced cardiac computed tomography angiography (CCTA) is the preferred modality for the visualization of the cardiac chambers and the coronaries. In clinical practice not every patient undergoes a CCTA scan; many patients receive only a non-contrast-enhanced calcium scoring CT scan (CTCS), which has less radiation dose and does not require the administration of contrast agent. Quantifying cardiac structures in such images is challenging, as they lack the contrast present in CCTA scans. Such quantification would however be relevant, as it enables population based studies with only a CTCS scan. The purpose of this work is therefore to investigate the feasibility of automatic segmentation and quantification of cardiac structures viz whole heart, left atrium, left ventricle, right atrium, right ventricle and aortic root from CTCS scans. A fully automatic multi-atlas-based segmentation approach is used to segment the cardiac structures. Results show that the segmentation overlap between the automatic method and that of the reference standard have a Dice similarity coefficient of 0.91 on average for the cardiac chambers. The mean surface-to-surface distance error over all the cardiac structures is 1.4+/- 1.7 mm. The automatically obtained cardiac chamber volumes using the CTCS scans have an excellent correlation when compared to the volumes in corresponding CCTA scans, a Pearson correlation coefficient (R) of 0.95 is obtained. Our fully automatic method enables large-scale assessment of cardiac structures on non-contrast-enhanced CT scans.

Contrast Enhancement Algorithm Based on Gap Adjustment for Histogram Equalization

PubMed Central

Chiu, Chung-Cheng; Ting, Chih-Chung

2016-01-01

Image enhancement methods have been widely used to improve the visual effects of images. Owing to its simplicity and effectiveness histogram equalization (HE) is one of the methods used for enhancing image contrast. However, HE may result in over-enhancement and feature loss problems that lead to unnatural look and loss of details in the processed images. Researchers have proposed various HE-based methods to solve the over-enhancement problem; however, they have largely ignored the feature loss problem. Therefore, a contrast enhancement algorithm based on gap adjustment for histogram equalization (CegaHE) is proposed. It refers to a visual contrast enhancement algorithm based on histogram equalization (VCEA), which generates visually pleasing enhanced images, and improves the enhancement effects of VCEA. CegaHE adjusts the gaps between two gray values based on the adjustment equation, which takes the properties of human visual perception into consideration, to solve the over-enhancement problem. Besides, it also alleviates the feature loss problem and further enhances the textures in the dark regions of the images to improve the quality of the processed images for human visual perception. Experimental results demonstrate that CegaHE is a reliable method for contrast enhancement and that it significantly outperforms VCEA and other methods. PMID:27338412

Contrast-enhanced color Doppler ultrasonography increases diagnostic accuracy for soft tissue tumors.

PubMed

Oebisu, Naoto; Hoshi, Manabu; Ieguchi, Makoto; Takada, Jun; Iwai, Tadashi; Ohsawa, Masahiko; Nakamura, Hiroaki

2014-10-01

Resolution of ultrasonography (US) has undergone marked development. Additionally, a new-generation contrast medium (Sonazoid) used for US is newly available. Contrast-enhanced US has been widely used for evaluating several types of cancer. In the present study, we evaluated the ability of color Doppler US (CDUS) and Sonazoid to differentiate between benign and malignant soft tissue tumors. A total of 180 patients (87 male, 93 female) were enrolled in the present study. The patient ages ranged from 1 to 91 years (mean 58.1±20.0 years). The maximum size, depth, tumor margins, shape, echogenicity and textural pattern were measured on gray-scale images. CDUS was used to evaluate the intratumoral blood flow with and without Sonazoid. Peak systolic flow velocity (Vp), mean flow velocity (Vm), resistivity index (RI) and pulsatility index (PI) of each detected intratumoral artery were automatically calculated with power Doppler US (PDUS). The present study included 118 benign and 62 malignant tumors. Statistical significances were found in size, depth, tumor margin and textural pattern but not in shape or echogenicity on gray-scale images. Before Sonazoid injection, CDUS findings showed 55% sensitivity, 77% specificity and 69% accuracy, whereas contrast-enhanced CDUS showed 87% sensitivity, 68% specificity and 74% accuracy. There were no statistically significant differences between malignant and benign tumors regarding the mean Vp, Vm, RI and PI values determined on PDUS. In conclusion, contrast-enhanced CDUS proved to be a reliable diagnostic tool for detecting malignant potential in soft tissue tumors.

Cryotherapy of Renal Lesions: Enhancement on Contrast-Enhanced Sonography on Postoperative Day 1 Does Not Imply Viable Tissue Persistence.

PubMed

Bertolotto, Michele; Siracusano, Salvatore; Cicero, Calogero; Iannelli, Mariano; Silvestri, Tommaso; Celia, Antonio; Guarise, Alessandro; Stacul, Fulvio

2017-02-01

To investigate whether persistent enhancement detected on contrast-enhanced sonography at postoperative day 1 (early contrast-enhanced sonography) after cryoablation of renal tumors implies the presence of residual viable tumor tissue, defined as residual enhancing tissue on reference imaging (computed tomography or magnetic resonance imaging) performed 6 months after the procedure. Seventy-four patients with percutaneous cryoablation of renal tumors had early contrast-enhanced sonography from November 2011 to August 2015. Two independent readers evaluated early contrast-enhanced sonographic findings and contrast-enhanced sonographic investigations performed 1 month after cryoablation of lesions that displayed enhancement on early contrast-enhanced sonography. They scored intralesional enhancement in 4 groups: no enhancement, few intralesional vessels, focal enhancing areas, and diffuse enhancement. Inter-reader agreement in evaluating lesion vascularity on early contrast-enhanced sonography was assessed with weighted κ statistics. Computed tomography or magnetic resonance imaging performed 6 months after the treatment was the reference procedure for assessing the absence or presence of residual disease. Inter-reader agreement in assessing intratumoral vascularization on early contrast-enhanced sonography was very good (κ = 0.90). Enhancement was absent for both readers in 33 of 74 cases; only a few intralesional vessels were visible in 21; whereas diffuse or focal enhancement was present in 13. In the remaining 7 patients, there were differences. Four lesions with focal enhancement on early contrast-enhanced sonography and 1 that was considered avascular had residual tumors on reference imaging. Ablation was successful in the remaining 69 of 74 patients (93%). After cryoablation, intratumoral enhancement on early contrast-enhanced sonography does not imply tumor cell viability. © 2016 by the American Institute of Ultrasound in Medicine.

Terminology for contrast-enhanced sonography: a practical glossary.

PubMed

Catalano, Orlando; Migaleddu, Vincenzo; Quaia, Emilio; Caruso, Giuseppe

2007-06-01

The purpose of this glossary is to offer an updated guide to the correct terminology for contrast-enhanced sonography. This report was prepared by a panel of radiologists from the Sonography Section of the Italian Association of Medical Radiology. A leading author prepared a list of terms based on a comprehensive literature survey. The draft was analyzed by 3 experts on the topic of contrast-enhanced sonography. These reviewers reached a consensus and prepared the final version. A list of 137 terms is included. These terms are briefly defined. Their proper application is discussed, with special reference to potential misleading uses. Contrast-enhanced sonography is a relatively new diagnostic tool, now entering clinical practice in several countries. Use of appropriate, universal terminology is mandatory in the scientific setting to allow comparison between different published experiences. Additionally, use of clear, standardized terminology is necessary in the clinical setting to facilitate report understanding by the referring physician. Standardized, nonequivocal nomenclature may also help future diffusion of sonographic contrast media in countries where their application is still not approved.

Image contrast enhancement using adjacent-blocks-based modification for local histogram equalization

NASA Astrophysics Data System (ADS)

Wang, Yang; Pan, Zhibin

2017-11-01

Infrared images usually have some non-ideal characteristics such as weak target-to-background contrast and strong noise. Because of these characteristics, it is necessary to apply the contrast enhancement algorithm to improve the visual quality of infrared images. Histogram equalization (HE) algorithm is a widely used contrast enhancement algorithm due to its effectiveness and simple implementation. But a drawback of HE algorithm is that the local contrast of an image cannot be equally enhanced. Local histogram equalization algorithms are proved to be the effective techniques for local image contrast enhancement. However, over-enhancement of noise and artifacts can be easily found in the local histogram equalization enhanced images. In this paper, a new contrast enhancement technique based on local histogram equalization algorithm is proposed to overcome the drawbacks mentioned above. The input images are segmented into three kinds of overlapped sub-blocks using the gradients of them. To overcome the over-enhancement effect, the histograms of these sub-blocks are then modified by adjacent sub-blocks. We pay more attention to improve the contrast of detail information while the brightness of the flat region in these sub-blocks is well preserved. It will be shown that the proposed algorithm outperforms other related algorithms by enhancing the local contrast without introducing over-enhancement effects and additional noise.

Contrast Enhancement for Thermal Acoustic Breast Cancer Imaging via Resonant Stimulation

DTIC Science & Technology

2008-03-01

AD_________________ Award Number: W81XWH-06-1-0389 TITLE: Contrast Enhancement for Thermal...5a. CONTRACT NUMBER Contrast Enhancement for Thermal Acoustic Breast Cancer Imaging via Resonant Stimulation 5b. GRANT NUMBER W81XWH-06-1-0389...13. SUPPLEMENTARY NOTES 14. ABSTRACT This research plans to develop enhanced contrast thermal acoustic imaging (TAI) technology for the

Contrast-Enhanced Image of Bellicia Crater

NASA Image and Video Library

2013-11-06

In this contrast-enhanced infrared image of Bellicia Crater on the giant asteroid Vesta, scientists from NASA Dawn mission can see signs of the mineral olivine. Olivine was not expected to be found at Bellicia.

Quantifying CO2 Emissions From Individual Power Plants From Space

NASA Astrophysics Data System (ADS)

Nassar, Ray; Hill, Timothy G.; McLinden, Chris A.; Wunch, Debra; Jones, Dylan B. A.; Crisp, David

2017-10-01

In order to better manage anthropogenic CO2 emissions, improved methods of quantifying emissions are needed at all spatial scales from the national level down to the facility level. Although the Orbiting Carbon Observatory 2 (OCO-2) satellite was not designed for monitoring power plant emissions, we show that in some cases, CO2 observations from OCO-2 can be used to quantify daily CO2 emissions from individual middle- to large-sized coal power plants by fitting the data to plume model simulations. Emission estimates for U.S. power plants are within 1-17% of reported daily emission values, enabling application of the approach to international sites that lack detailed emission information. This affirms that a constellation of future CO2 imaging satellites, optimized for point sources, could monitor emissions from individual power plants to support the implementation of climate policies.

Optimization of Contrast Detection Power with Probabilistic Behavioral Information

PubMed Central

Cordes, Dietmar; Herzmann, Grit; Nandy, Rajesh; Curran, Tim

2012-01-01

Recent progress in the experimental design for event-related fMRI experiments made it possible to find the optimal stimulus sequence for maximum contrast detection power using a genetic algorithm. In this study, a novel algorithm is proposed for optimization of contrast detection power by including probabilistic behavioral information, based on pilot data, in the genetic algorithm. As a particular application, a recognition memory task is studied and the design matrix optimized for contrasts involving the familiarity of individual items (pictures of objects) and the recollection of qualitative information associated with the items (left/right orientation). Optimization of contrast efficiency is a complicated issue whenever subjects’ responses are not deterministic but probabilistic. Contrast efficiencies are not predictable unless behavioral responses are included in the design optimization. However, available software for design optimization does not include options for probabilistic behavioral constraints. If the anticipated behavioral responses are included in the optimization algorithm, the design is optimal for the assumed behavioral responses, and the resulting contrast efficiency is greater than what either a block design or a random design can achieve. Furthermore, improvements of contrast detection power depend strongly on the behavioral probabilities, the perceived randomness, and the contrast of interest. The present genetic algorithm can be applied to any case in which fMRI contrasts are dependent on probabilistic responses that can be estimated from pilot data. PMID:22326984

Enhanced Positive-Contrast Visualization of Paramagnetic Contrast Agents Using Phase Images

PubMed Central

Mills, Parker H.; Ahrens, Eric T.

2009-01-01

Iron oxide–based MRI contrast agents are increasingly being used to noninvasively track cells, target molecular epitopes, and monitor gene expression in vivo. Detecting regions of contrast agent accumulation can be challenging if resulting contrast is subtle relative to endogenous tissue hypointensities. A postprocessing method is presented that yields enhanced positive-contrast images from the phase map associated with T2*-weighted MRI data. As examples, the method was applied to an agarose gel phantom doped with superparamagnetic iron-oxide nanoparticles and in vivo and ex vivo mouse brains inoculated with recombinant viruses delivering transgenes that induce overexpression of paramagnetic ferritin. Overall, this approach generates images that exhibit a 1- to 8-fold improvement in contrast-to-noise ratio in regions where paramagnetic agents are present compared to conventional magnitude images. This approach can be used in conjunction with conventional T2* pulse sequences, requires no prescans or increased scan time, and can be applied retrospectively to previously acquired data. PMID:19780169

Color Retinal Image Enhancement Based on Luminosity and Contrast Adjustment.

PubMed

Zhou, Mei; Jin, Kai; Wang, Shaoze; Ye, Juan; Qian, Dahong

2018-03-01

Many common eye diseases and cardiovascular diseases can be diagnosed through retinal imaging. However, due to uneven illumination, image blurring, and low contrast, retinal images with poor quality are not useful for diagnosis, especially in automated image analyzing systems. Here, we propose a new image enhancement method to improve color retinal image luminosity and contrast. A luminance gain matrix, which is obtained by gamma correction of the value channel in the HSV (hue, saturation, and value) color space, is used to enhance the R, G, and B (red, green and blue) channels, respectively. Contrast is then enhanced in the luminosity channel of L * a * b * color space by CLAHE (contrast-limited adaptive histogram equalization). Image enhancement by the proposed method is compared to other methods by evaluating quality scores of the enhanced images. The performance of the method is mainly validated on a dataset of 961 poor-quality retinal images. Quality assessment (range 0-1) of image enhancement of this poor dataset indicated that our method improved color retinal image quality from an average of 0.0404 (standard deviation 0.0291) up to an average of 0.4565 (standard deviation 0.1000). The proposed method is shown to achieve superior image enhancement compared to contrast enhancement in other color spaces or by other related methods, while simultaneously preserving image naturalness. This method of color retinal image enhancement may be employed to assist ophthalmologists in more efficient screening of retinal diseases and in development of improved automated image analysis for clinical diagnosis.

Contrast-enhanced CT with a High-Affinity Cationic Contrast Agent for Imaging ex Vivo Bovine, Intact ex Vivo Rabbit, and in Vivo Rabbit Cartilage

PubMed Central

Stewart, Rachel C.; Bansal, Prashant N.; Entezari, Vahid; Lusic, Hrvoje; Nazarian, Rosalynn M.; Snyder, Brian D.

2013-01-01

Purpose: To quantify the affinity of a cationic computed tomography (CT) contrast agent (CA4+) and that of an anionic contrast agent (ioxaglate) to glycosaminoglycans (GAGs) in ex vivo cartilage tissue explants and to characterize the in vivo diffusion kinetics of CA4+ and ioxaglate in a rabbit model. Materials and Methods: All in vivo procedures were approved by the institutional animal care and use committee. The affinities of ioxaglate and CA4+ to GAGs in cartilage (six bovine osteochondral plugs) were quantified by means of a modified binding assay using micro-CT after plug equilibration in serial dilutions of each agent. The contrast agents were administered intraarticularly to the knee joints of five New Zealand white rabbits to determine the in vivo diffusion kinetics and cartilage tissue imaging capabilities. Kinetics of diffusion into the femoral groove cartilage and relative contrast agent uptake into bovine plugs were characterized by means of nonlinear mixed-effects models. Diffusion time constants (τ) were compared by using a Student t test. Results: The uptake of CA4+ in cartilage was consistently over 100% of the reservoir concentration, whereas it was only 59% for ioxaglate. In vivo, the contrast material–enhanced cartilage reached a steady CT attenuation for both CA4+ and ioxaglate, with τ values of 13.8 and 6.5 minutes, respectively (P = .04). The cartilage was easily distinguishable from the surrounding tissues for CA4+ (12 mg of iodine per milliliter); comparatively, the anionic contrast agent provided less favorable imaging results, even when a higher concentration was used (80 mg of iodine per milliliter). Conclusion: The affinity of the cationic contrast agent CA4+ to GAGs enables high-quality imaging and segmentation of ex vivo bovine and rabbit cartilage, as well as in vivo rabbit cartilage. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112246/-/DC1 PMID:23192774

Quantitative evaluation of contrast agent uptake in standard fat-suppressed dynamic contrast-enhanced MRI examinations of the breast.

PubMed

Kousi, Evanthia; Smith, Joely; Ledger, Araminta E; Scurr, Erica; Allen, Steven; Wilson, Robin M; O'Flynn, Elizabeth; Pope, Romney J E; Leach, Martin O; Schmidt, Maria A

2018-01-01

To propose a method to quantify T 1 and contrast agent uptake in breast dynamic contrast-enhanced (DCE) examinations undertaken with standard clinical fat-suppressed MRI sequences and to demonstrate the proposed approach by comparing the enhancement characteristics of lobular and ductal carcinomas. A standard fat-suppressed DCE of the breast was performed at 1.5 T (Siemens Aera), followed by the acquisition of a proton density (PD)-weighted sequence, also fat suppressed. Both sequences were characterized with test objects (T 1 ranging from 30 ms to 2,400 ms) and calibration curves were obtained to enable T 1 calculation. The reproducibility and accuracy of the calibration curves were also investigated. Healthy volunteers and patients were scanned with Ethics Committee approval. The effect of B 0 field inhomogeneity was assessed in test objects and healthy volunteers. The T 1 of breast tumors was calculated at different time points (pre-, peak-, and post-contrast agent administration) for 20 patients, pre-treatment (10 lobular and 10 ductal carcinomas) and the two cancer types were compared (Wilcoxon rank-sum test). The calibration curves proved to be highly reproducible (coefficient of variation under 10%). T 1 measurements were affected by B 0 field inhomogeneity, but frequency shifts below 50 Hz introduced only 3% change to fat-suppressed T 1 measurements of breast parenchyma in volunteers. The values of T 1 measured pre-, peak-, and post-contrast agent administration demonstrated that the dynamic range of the DCE sequence was correct, that is, image intensity is approximately directly proportional to 1/T 1 for that range. Significant differences were identified in the width of the distributions of the post-contrast T 1 values between lobular and ductal carcinomas (P < 0.05); lobular carcinomas demonstrated a wider range of post-contrast T 1 values, potentially related to their infiltrative growth pattern. This work has demonstrated the feasibility of fat

Diagnostic accuracy of contrast-enhanced computed tomography and contrast-enhanced magnetic resonance imaging of small renal masses in real practice: sensitivity and specificity according to subjective radiologic interpretation.

PubMed

Kim, Jae Heon; Sun, Hwa Yeon; Hwang, Jiyoung; Hong, Seong Sook; Cho, Yong Jin; Doo, Seung Whan; Yang, Won Jae; Song, Yun Seob

2016-10-12

The aim of this study was to investigate the diagnostic accuracy of contrast-enhanced computed tomography (CT) and contrast-enhanced magnetic resonance imaging (MRI) of small renal masses in real practice. Contrast-enhanced CT and MRI were performed between February 2008 and February 2013 on 68 patients who had suspected small (≤4 cm) renal cell carcinoma (RCC) based on ultrasonographic measurements. CT and MRI radiographs were reviewed, and the findings of small renal masses were re-categorized into five dichotomized scales by the same two radiologists who had interpreted the original images. Receiver operating characteristics curve analysis was performed, and sensitivity and specificity were determined. Among the 68 patients, 60 (88.2 %) had RCC and eight had benign disease. The diagnostic accuracy rates of contrast-enhanced CT and MRI were 79.41 and 88.23 %, respectively. Diagnostic accuracy was greater when using contrast-enhanced MRI because too many masses (67.6 %) were characterized as "4 (probably solid cancer) or 5 (definitely solid cancer)." The sensitivity of contrast-enhanced CT and MRI for predicting RCC were 79.7 and 88.1 %, respectively. The specificities of contrast-enhanced CT and MRI for predicting RCC were 44.4 and 33.3 %, respectively. Fourteen diagnoses (20.5 %) were missed or inconsistent compared with the final pathological diagnoses. One appropriate nephroureterectomy and five unnecessary percutaneous biopsies were performed for RCC. Seven unnecessary partial nephrectomies were performed for benign disease. Although contrast-enhanced CT and MRI showed high sensitivity for detecting small renal masses, specificity remained low.

Analysis of achilles tendon vascularity with second-generation contrast-enhanced ultrasound.

PubMed

Genovese, Eugenio; Ronga, Mario; Recaldini, Chiara; Fontana, Federico; Callegari, Leonardo; Maffulli, Nicola; Fugazzola, Carlo

2011-01-01

To compare morphological, power Doppler, and contrast-enhanced ultrasound (CEUS) features of the Achilles tendon between asymptomatic athletes and athletes who had undergone surgical repair of a previous rupture. Twenty-four athletes were divided in two groups (A and B). Group A included 14 patients with a median age of 32 years (range 27 to 47 years) who had undergone surgical repair for unilateral Achilles tendon rupture. Group B (control group) included 10 subjects with a median age of 34 years (range 27 to 40 years) with no previous or present history of tendinopathy. All patients were evaluated with ultrasound, power Doppler, and CEUS with second-generation contrast agent. We studied the uninjured Achilles tendon in athletes of group A and either the left or the right Achilles tendon of the athletes in group B. CEUS showed a significantly greater ability to detect a greater number of vascular spots within the uninjured tendon of group A compared to group B (<0.05). In athletes who had suffered a tear of an Achilles tendon, CEUS detected small vessels that were not identified by power Doppler ultrasound in the uninjured contralateral Achilles tendon. CEUS is useful to evaluate vascularity not detected by other imaging techniques. Vascularity in the uninjured tendon seems to be increased in patients who had a previous rupture. Copyright © 2011 Wiley Periodicals, Inc.

Patterns of contrast enhancement in the brain and meninges.

PubMed

Smirniotopoulos, James G; Murphy, Frances M; Rushing, Elizabeth J; Rees, John H; Schroeder, Jason W

2007-01-01

Contrast material enhancement for cross-sectional imaging has been used since the mid 1970s for computed tomography and the mid 1980s for magnetic resonance imaging. Knowledge of the patterns and mechanisms of contrast enhancement facilitate radiologic differential diagnosis. Brain and spinal cord enhancement is related to both intravascular and extravascular contrast material. Extraaxial enhancing lesions include primary neoplasms (meningioma), granulomatous disease (sarcoid), and metastases (which often manifest as mass lesions). Linear pachymeningeal (dura-arachnoid) enhancement occurs after surgery and with spontaneous intracranial hypotension. Leptomeningeal (pia-arachnoid) enhancement is present in meningitis and meningoencephalitis. Superficial gyral enhancement is seen after reperfusion in cerebral ischemia, during the healing phase of cerebral infarction, and with encephalitis. Nodular subcortical lesions are typical for hematogenous dissemination and may be neoplastic (metastases) or infectious (septic emboli). Deeper lesions may form rings or affect the ventricular margins. Ring enhancement that is smooth and thin is typical of an organizing abscess, whereas thick irregular rings suggest a necrotic neoplasm. Some low-grade neoplasms are "fluid-secreting," and they may form heterogeneously enhancing lesions with an incomplete ring sign as well as the classic "cyst-with-nodule" morphology. Demyelinating lesions, including both classic multiple sclerosis and tumefactive demyelination, may also create an open ring or incomplete ring sign. Thick and irregular periventricular enhancement is typical for primary central nervous system lymphoma. Thin enhancement of the ventricular margin occurs with infectious ependymitis. Understanding the classic patterns of lesion enhancement--and the radiologic-pathologic mechanisms that produce them--can improve image assessment and differential diagnosis.

Preoperative prognostic value of dynamic contrast-enhanced MRI-derived contrast transfer coefficient and plasma volume in patients with cerebral gliomas.

PubMed

Nguyen, T B; Cron, G O; Mercier, J F; Foottit, C; Torres, C H; Chakraborty, S; Woulfe, J; Jansen, G H; Caudrelier, J M; Sinclair, J; Hogan, M J; Thornhill, R E; Cameron, I G

2015-01-01

The prognostic value of dynamic contrast-enhanced MR imaging-derived plasma volume obtained in tumor and the contrast transfer coefficient has not been well-established in patients with gliomas. We determined whether plasma volume and contrast transfer coefficient in tumor correlated with survival in patients with gliomas in addition to other factors such as age, type of surgery, preoperative Karnofsky score, contrast enhancement, and histopathologic grade. This prospective study included 46 patients with a new pathologically confirmed diagnosis of glioma. The contrast transfer coefficient and plasma volume obtained in tumor maps were calculated directly from the signal-intensity curve without T1 measurements, and values were obtained from multiple small ROIs placed within tumors. Survival curve analysis was performed by dichotomizing patients into groups of high and low contrast transfer coefficient and plasma volume. Univariate analysis was performed by using dynamic contrast-enhanced parameters and clinical factors. Factors that were significant on univariate analysis were entered into multivariate analysis. For all patients with gliomas, survival was worse for groups of patients with high contrast transfer coefficient and plasma volume obtained in tumor (P < .05). In subgroups of high- and low-grade gliomas, survival was worse for groups of patients with high contrast transfer coefficient and plasma volume obtained in tumor (P < .05). Univariate analysis showed that factors associated with lower survival were age older than 50 years, low Karnofsky score, biopsy-only versus resection, marked contrast enhancement versus no/mild enhancement, high contrast transfer coefficient, and high plasma volume obtained in tumor (P < .05). In multivariate analysis, a low Karnofsky score, biopsy versus resection in combination with marked contrast enhancement, and a high contrast transfer coefficient were associated with lower survival rates (P < .05). In patients with glioma

Real-time monitoring of radiofrequency ablation and postablation assessment: accuracy of contrast-enhanced US in experimental rat liver model.

PubMed

Wu, Hanping; Wilkins, Luke R; Ziats, Nicholas P; Haaga, John R; Exner, Agata A

2014-01-01

To examine the accuracy of the unenhanced zone at contrast material-enhanced ultrasonography (US) in predicting coagulative necrosis during and 21 days after radiofrequency (RF) ablation by using radiologic-pathologic comparison. Animal studies were approved by the Institutional Animal Care and Use Committee. The livers of 28 rats underwent US-guided RF ablation. In four animals, contrast-enhanced US was performed during ablation and 2 hours and 2, 7, 14, and 21 days after ablation. The unenhanced zone area on US images was measured. DiI-labeled microbubbles were administered during ablation at 2, 4, and 6 minutes or at 2 hours and 2, 7, 14, and 21 days after ablation in the remaining 24 animals (n = 3 at each time point). One minute later, the animal was euthanized, and the ablated liver was harvested. Tissue samples were imaged to quantify total fluorescence, and NADH staining was performed on the same slice. Hematoxylin-eosin staining was also performed. The findings on fluorescence images, NADH-stained images, and hematoxylin-eosin-stained images were compared. The areas of DiI bubble-negative zones, NADH-negative zones, and lightly NADH-staining zones were measured. Data were analyzed by using one-way analysis of variance. The area of the unenhanced zone on contrast-enhanced US images increased during RF ablation and reached a maximum within 2 days after ablation. At histopathologic examination, a transition zone manifested adjacent to the coagulation zone until 2 days after ablation. The DiI-bubble negative zone on fluorescence images and the damaged zone (transition zone plus coagulation zone) on NADH-stained images increased rapidly within 2 hours after ablation, then slowly reached the maximum on day 2. The ratios of the mean areas of these two zones at hour 2 to those at day 2 were 94.6% and 95.6%, respectively. High uniformity between the damaged zone on NADH-stained images and the DiI bubble-negative zone on fluorescence images was noted at all time

Enhanced renal image contrast by ethanol fixation in phase-contrast X-ray computed tomography.

PubMed

Shirai, Ryota; Kunii, Takuya; Yoneyama, Akio; Ooizumi, Takahito; Maruyama, Hiroko; Lwin, Thet Thet; Hyodo, Kazuyuki; Takeda, Tohoru

2014-07-01

Phase-contrast X-ray imaging using a crystal X-ray interferometer can depict the fine structures of biological objects without the use of a contrast agent. To obtain higher image contrast, fixation techniques have been examined with 100% ethanol and the commonly used 10% formalin, since ethanol causes increased density differences against background due to its physical properties and greater dehydration of soft tissue. Histological comparison was also performed. A phase-contrast X-ray system was used, fitted with a two-crystal X-ray interferometer at 35 keV X-ray energy. Fine structures, including cortex, tubules in the medulla, and the vessels of ethanol-fixed kidney could be visualized more clearly than that of formalin-fixed tissues. In the optical microscopic images, shrinkage of soft tissue and decreased luminal space were observed in ethanol-fixed kidney; and this change was significantly shown in the cortex and outer stripe of the outer medulla. The ethanol fixation technique enhances image contrast by approximately 2.7-3.2 times in the cortex and the outer stripe of the outer medulla; the effect of shrinkage and the physical effect of ethanol cause an increment of approximately 78% and 22%, respectively. Thus, the ethanol-fixation technique enables the image contrast to be enhanced in phase-contrast X-ray imaging.

The added value of 68Ga-DOTA-TATE-PET to contrast-enhanced CT for primary site detection in CUP of neuroendocrine origin.

PubMed

Kazmierczak, Philipp M; Rominger, Axel; Wenter, Vera; Spitzweg, Christine; Auernhammer, Christoph; Angele, Martin K; Rist, Carsten; Cyran, Clemens C

2017-04-01

To quantify the additional value of 68 Ga-DOTA-TATE PET/CT in comparison with contrast-enhanced CT alone for primary tumour detection in neuroendocrine cancer of unknown primary (CUP-NET). In total, 38 consecutive patients (27 men, 11 women; mean age 62 years) with histologically proven CUP-NET who underwent a contrast-enhanced 68 Ga-DOTA-TATE PET/CT scan for primary tumour detection and staging between 2010 and 2014 were included in this IRB-approved retrospective study. Two blinded readers independently analysed the contrast-enhanced CT and 68 Ga-DOTA-TATE PET datasets separately and noted from which modality they suspected a primary tumour. Consensus was reached if the results were divergent. Postoperative histopathology (24 patients) and follow-up 68 Ga-DOTA-TATE PET/CT imaging (14 patients) served as the reference standards and statistical measures of diagnostic accuracy were calculated accordingly. The majority of confirmed primary tumours were located in the abdomen (ileum in 19 patients, pancreas in 12, lung in 2, small pelvis in 1). High interobserver agreement was noted regarding the suspected primary tumour site (Cohen's k 0.90, p < 0.001). 68 Ga-DOTA-TATE PET demonstrated a significantly higher sensitivity (94 % vs. 63 %, p = 0.005) and a significantly higher accuracy (87 % vs. 68 %, p = 0.003) than contrast-enhanced CT. Ga-DOTA-TATE PET/CT compared with contrast-enhanced CT alone provides an improvement in sensitivity of 50 % and an improvement in accuracy of 30 % in primary tumour detection in CUP-NET. • 68 Ga-DOTA-TATE PET augments the sensitivity of contrast-enhanced CT by 50 % • 68 Ga-DOTA-TATE PET augments the accuracy of contrast-enhanced CT by 30 % • Somatostatin receptor-targeted hybrid imaging optimizes primary tumour detection in CUP-NET.

Exogenous attention enhances 2nd-order contrast sensitivity

PubMed Central

Barbot, Antoine; Landy, Michael S.; Carrasco, Marisa

2011-01-01

Natural scenes contain a rich variety of contours that the visual system extracts to segregrate the retinal image into perceptually coherent regions. Covert spatial attention helps extract contours by enhancing contrast sensitivity for 1st-order, luminance-defined patterns at attended locations, while reducing sensitivity at unattended locations, relative to neutral attention allocation. However, humans are also sensitive to 2nd-order patterns such as spatial variations of texture, which are predominant in natural scenes and cannot be detected by linear mechanisms. We assess whether and how exogenous attention—the involuntary and transient capture of spatial attention—affects the contrast sensitivity of channels sensitive to 2nd-order, texture-defined patterns. Using 2nd-order, texture-defined stimuli, we demonstrate that exogenous attention increases 2nd-order contrast sensitivity at the attended location, while decreasing it at unattended locations, relative to a neutral condition. By manipulating both 1st- and 2nd-order spatial frequency, we find that the effects of attention depend both on 2nd-order spatial frequency of the stimulus and the observer’s 2nd-order spatial resolution at the target location. At parafoveal locations, attention enhances 2nd-order contrast sensitivity to high, but not to low 2nd-order spatial frequencies; at peripheral locations attention also enhances sensitivity to low 2nd-order spatial frequencies. Control experiments rule out the possibility that these effects might be due to an increase in contrast sensitivity at the 1st-order stage of visual processing. Thus, exogenous attention affects 2nd-order contrast sensitivity at both attended and unattended locations. PMID:21356228

Diagnostic value of contrast-enhanced ultrasonography in the characterization of ovarian tumors☆

PubMed Central

Sconfienza, L.M.; Perrone, N.; Delnevo, A.; Lacelli, F.; Murolo, C.; Gandolfo, N.; Serafini, G.

2009-01-01

Introduction Vascularity influences the characteristics of gynecologic tumors observed with direct imaging techniques that reveal the macrovascular component of these lesions (color and power Doppler) and with indirect imaging involving the administration of contrast agents to examine the microcirculation and interstitial perfusion (contrast-enhanced computed tomography [CT] and magnetic resonance [MR] imaging). The purpose of this study was to determine whether contrast-enhanced ultrasonography (CEUS) of ovarian lesions provides useful information that cannot be obtained with conventional US. Materials and methods We used CEUS to assess 72 nonspecific adnexal lesions in 61 patients. CEUS was performed with a 4.8-ml bolus of a second-generation ultrasonographic contrast agent and dedicated imaging algorithms. For each lesion, B-mode morphology, CEUS morphology, and time/intensity curves were evaluated. Results In 8/61 cases (13.1%) CEUS offered no additional morphovascular information. In 38/61 cases (62.3%), it provided additional information that did not modify the management of the lesion, and in 15/61 cases (24.6%) it gave additional information that modified the management of the lesion. Malignant lesions were characterized by significantly shorter times to peak enhancement (11.9 ± 3.1 s vs 19.8 ± 4.0 s p < 0.01) and significantly higher peak intensity (24.7 ± 4.2 dB vs 17.8 ± 3.3 dB p < 0.01) compared with benign lesions. Conclusions CEUS improves diagnostic confidence in the characterization of liquid-corpuscular lesions where conventional US is inconclusive. CEUS can be proposed as a valid alternative to CT and MR. However, information obtained by CEUS influences the therapy in a limited percentage of cases (24.6%). PMID:23396092

Diagnostic value of contrast-enhanced ultrasonography in the characterization of ovarian tumors().

PubMed

Sconfienza, L M; Perrone, N; Delnevo, A; Lacelli, F; Murolo, C; Gandolfo, N; Serafini, G

2010-03-01

Vascularity influences the characteristics of gynecologic tumors observed with direct imaging techniques that reveal the macrovascular component of these lesions (color and power Doppler) and with indirect imaging involving the administration of contrast agents to examine the microcirculation and interstitial perfusion (contrast-enhanced computed tomography [CT] and magnetic resonance [MR] imaging). The purpose of this study was to determine whether contrast-enhanced ultrasonography (CEUS) of ovarian lesions provides useful information that cannot be obtained with conventional US. We used CEUS to assess 72 nonspecific adnexal lesions in 61 patients. CEUS was performed with a 4.8-ml bolus of a second-generation ultrasonographic contrast agent and dedicated imaging algorithms. For each lesion, B-mode morphology, CEUS morphology, and time/intensity curves were evaluated. In 8/61 cases (13.1%) CEUS offered no additional morphovascular information. In 38/61 cases (62.3%), it provided additional information that did not modify the management of the lesion, and in 15/61 cases (24.6%) it gave additional information that modified the management of the lesion. Malignant lesions were characterized by significantly shorter times to peak enhancement (11.9 ± 3.1 s vs 19.8 ± 4.0 s p < 0.01) and significantly higher peak intensity (24.7 ± 4.2 dB vs 17.8 ± 3.3 dB p < 0.01) compared with benign lesions. CEUS improves diagnostic confidence in the characterization of liquid-corpuscular lesions where conventional US is inconclusive. CEUS can be proposed as a valid alternative to CT and MR. However, information obtained by CEUS influences the therapy in a limited percentage of cases (24.6%).

Including the effect of motion artifacts in noise and performance analysis of dual-energy contrast-enhanced mammography

NASA Astrophysics Data System (ADS)

Allec, N.; Abbaszadeh, S.; Scott, C. C.; Lewin, J. M.; Karim, K. S.

2012-12-01

In contrast-enhanced mammography (CEM), the dual-energy dual-exposure technique, which can leverage existing conventional mammography infrastructure, relies on acquiring the low- and high-energy images using two separate exposures. The finite time between image acquisition leads to motion artifacts in the combined image. Motion artifacts can lead to greater anatomical noise in the combined image due to increased mismatch of the background tissue in the images to be combined, however the impact has not yet been quantified. In this study we investigate a method to include motion artifacts in the dual-energy noise and performance analysis. The motion artifacts are included via an extended cascaded systems model. To validate the model, noise power spectra of a previous dual-energy clinical study are compared to that of the model. The ideal observer detectability is used to quantify the effect of motion artifacts on tumor detectability. It was found that the detectability can be significantly degraded when motion is present (e.g., detectability of 2.5 mm radius tumor decreased by approximately a factor of 2 for translation motion on the order of 1000 μm). The method presented may be used for a more comprehensive theoretical noise and performance analysis and fairer theoretical performance comparison between dual-exposure techniques, where motion artifacts are present, and single-exposure techniques, where low- and high-energy images are acquired simultaneously and motion artifacts are absent.

Including the effect of motion artifacts in noise and performance analysis of dual-energy contrast-enhanced mammography.

PubMed

Allec, N; Abbaszadeh, S; Scott, C C; Lewin, J M; Karim, K S

2012-12-21

In contrast-enhanced mammography (CEM), the dual-energy dual-exposure technique, which can leverage existing conventional mammography infrastructure, relies on acquiring the low- and high-energy images using two separate exposures. The finite time between image acquisition leads to motion artifacts in the combined image. Motion artifacts can lead to greater anatomical noise in the combined image due to increased mismatch of the background tissue in the images to be combined, however the impact has not yet been quantified. In this study we investigate a method to include motion artifacts in the dual-energy noise and performance analysis. The motion artifacts are included via an extended cascaded systems model. To validate the model, noise power spectra of a previous dual-energy clinical study are compared to that of the model. The ideal observer detectability is used to quantify the effect of motion artifacts on tumor detectability. It was found that the detectability can be significantly degraded when motion is present (e.g., detectability of 2.5 mm radius tumor decreased by approximately a factor of 2 for translation motion on the order of 1000 μm). The method presented may be used for a more comprehensive theoretical noise and performance analysis and fairer theoretical performance comparison between dual-exposure techniques, where motion artifacts are present, and single-exposure techniques, where low- and high-energy images are acquired simultaneously and motion artifacts are absent.

Nanodiamond-Manganese dual mode MRI contrast agents for enhanced liver tumor detection.

PubMed

Hou, Weixin; Toh, Tan Boon; Abdullah, Lissa Nurrul; Yvonne, Tay Wei Zheng; Lee, Kuan J; Guenther, Ilonka; Chow, Edward Kai-Hua

2017-04-01

Contrast agent-enhanced magnetic resonance (MR) imaging is critical for the diagnosis and monitoring of a number of diseases, including cancer. Certain clinical applications, including the detection of liver tumors, rely on both T1 and T2-weighted images even though contrast agent-enhanced MR imaging is not always reliable. Thus, there is a need for improved dual mode contrast agents with enhanced sensitivity. We report the development of a nanodiamond-manganese dual mode contrast agent that enhanced both T1 and T2-weighted MR imaging. Conjugation of manganese to nanodiamonds resulted in improved longitudinal and transverse relaxivity efficacy over unmodified MnCl 2 as well as clinical contrast agents. Following intravenous administration, nanodiamond-manganese complexes outperformed current clinical contrast agents in an orthotopic liver cancer mouse model while also reducing blood serum concentration of toxic free Mn 2+ ions. Thus, nanodiamond-manganese complexes may serve as more effective dual mode MRI contrast agent, particularly in cancer. Copyright © 2016 Elsevier Inc. All rights reserved.

Comparison of the performance of tracer kinetic model-driven registration for dynamic contrast enhanced MRI using different models of contrast enhancement.

PubMed

Buonaccorsi, Giovanni A; Roberts, Caleb; Cheung, Sue; Watson, Yvonne; O'Connor, James P B; Davies, Karen; Jackson, Alan; Jayson, Gordon C; Parker, Geoff J M

2006-09-01

The quantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) data is subject to model fitting errors caused by motion during the time-series data acquisition. However, the time-varying features that occur as a result of contrast enhancement can confound motion correction techniques based on conventional registration similarity measures. We have therefore developed a heuristic, locally controlled tracer kinetic model-driven registration procedure, in which the model accounts for contrast enhancement, and applied it to the registration of abdominal DCE-MRI data at high temporal resolution. Using severely motion-corrupted data sets that had been excluded from analysis in a clinical trial of an antiangiogenic agent, we compared the results obtained when using different models to drive the tracer kinetic model-driven registration with those obtained when using a conventional registration against the time series mean image volume. Using tracer kinetic model-driven registration, it was possible to improve model fitting by reducing the sum of squared errors but the improvement was only realized when using a model that adequately described the features of the time series data. The registration against the time series mean significantly distorted the time series data, as did tracer kinetic model-driven registration using a simpler model of contrast enhancement. When an appropriate model is used, tracer kinetic model-driven registration influences motion-corrupted model fit parameter estimates and provides significant improvements in localization in three-dimensional parameter maps. This has positive implications for the use of quantitative DCE-MRI for example in clinical trials of antiangiogenic or antivascular agents.

A preliminary evaluation of self-made nanobubble in contrast-enhanced ultrasound imaging

NASA Astrophysics Data System (ADS)

Li, Chunfang; Wu, Kaizhi; Li, Jing; Liu, Haijuan; Zhou, Qibing; Ding, Mingyue

2014-03-01

Nanoscale bubbles (nanobubbles) have been reported to improve contrast in tumor-targeted ultrasound imaging due to the enhanced permeation and retention effects at tumor vascular leaks. In this work, a self-made nanobubble ultrasound contrast agent was preliminarily characterized and evaluated in-vitro and in-vivo. Fundamental properties such as morphology appearance, size distribution, zeta potential, bubble concentration (bubble numbers per milliliter contrast agent suspension) and the stability of nanobubbles were assessed by light microscope and particle sizing analysis. Then the concentration intensity curve and time intensity curves (TICs) were acquired by ultrasound imaging experiment in-vitro. Finally, the contrast-enhanced ultrasonography was performed on rat to investigate the procedure of liver perfusion. The results showed that the nanobubbles had good shape and uniform distribution with the average diameter of 507.9 nm, polydispersity index (PDI) of 0.527, and zeta potential of -19.17 mV. Significant contrast enhancement was observed in in-vitro ultrasound imaging, demonstrating that the self-made nanobubbles can enhance the contrast effect of ultrasound imaging efficiently in-vitro. Slightly contrast enhancement was observed in in-vivo ultrasound imaging, indicating that the nanobubbles are not stable enough in-vivo. Future work will be focused on improving the ultrasonic imaging performance, stability, and antibody binding of the nanoscale ultrasound contrast agent.

Attention enhances contrast appearance via increased input baseline of neural responses

PubMed Central

Cutrone, Elizabeth K.; Heeger, David J.; Carrasco, Marisa

2014-01-01

Covert spatial attention increases the perceived contrast of stimuli at attended locations, presumably via enhancement of visual neural responses. However, the relation between perceived contrast and the underlying neural responses has not been characterized. In this study, we systematically varied stimulus contrast, using a two-alternative, forced-choice comparison task to probe the effect of attention on appearance across the contrast range. We modeled performance in the task as a function of underlying neural contrast-response functions. Fitting this model to the observed data revealed that an increased input baseline in the neural responses accounted for the enhancement of apparent contrast with spatial attention. PMID:25549920

Frequency, outcome, and risk factors of contrast media extravasation in 142,651 intravenous contrast-enhanced CT scans.

PubMed

Hwang, Eui Jin; Shin, Cheong-Il; Choi, Young Hun; Park, Chang Min

2018-06-06

To evaluate the frequency, outcome, and risk factors of intravenous contrast media (CM) extravasation during contrast-enhanced CT scans in a large population. After institutional review board approval, 142,651 patients (72,976 males and 69,675 females; mean age, 59.9 ± 13.0 years) who underwent contrast-enhanced CT scans with intravenous CM between January 2015 and April 2017 were retrospectively included. The frequency of CM extravasations and their clinical outcomes were investigated. Risk factors of CM extravasation were evaluated using logistic regression with generalized estimating equation analyses. In addition, the frequency and risk factors of large-volume (≥100 ml) CM extravasation were also investigated. CM extravasation occurred in 0.23% (321/142,651) of patients, all of which were of mild degree and resolved without any sequelae through conservative management. Multivariate analysis revealed that female gender [odds ratio (OR) = 1.61; p < 0.001], 60 < age ≤ 70 years (OR = 1.71; p = 0.004) or age > 70 years (OR = 2.49; p < 0.001), patients in general wards (OR = 2.71; p < 0.001) or ICUs (OR = 4.76; p < 0.001), 9.4 < CM viscosity ≤ 10.0 (OR = 1.65; p = 0.015), 10.0 < CM viscosity ≤ 10.6 (OR = 1.60; p = 0.002), and CM viscosity > 16.0 (OR = 2.55, p < 0.001) were independent risk factors for CM extravasation. CM extravasation during contrast-enhanced CT scans was uncommon with no substantial clinical consequences. Several risk factors that may have the potential to reduce the occurrence of CM extravasation were identified. • The observed frequency of contrast media extravasation during contrast-enhanced CT scans was 0.23% (321/142,651). • Significant risk factors for contrast media extravasation were female gender, age older than 60 years, patients in general wards or ICUs, and the viscosity of contrast media greater than 9.4 mPa∙s. • The main preventive action for contrast media extravasation would be to lower the viscosity of contrast

Is nitrogen transfer among plants enhanced by contrasting nutrient-acquisition strategies?

PubMed

Teste, François P; Veneklaas, Erik J; Dixon, Kingsley W; Lambers, Hans

2015-01-01

Nitrogen (N) transfer among plants has been found where at least one plant can fix N2 . In nutrient-poor soils, where plants with contrasting nutrient-acquisition strategies (without N2 fixation) co-occur, it is unclear if N transfer exists and what promotes it. A novel multi-species microcosm pot experiment was conducted to quantify N transfer between arbuscular mycorrhizal (AM), ectomycorrhizal (EM), dual AM/EM, and non-mycorrhizal cluster-rooted plants in nutrient-poor soils with mycorrhizal mesh barriers. We foliar-fed plants with a K(15) NO3 solution to quantify one-way N transfer from 'donor' to 'receiver' plants. We also quantified mycorrhizal colonization and root intermingling. Transfer of N between plants with contrasting nutrient-acquisition strategies occurred at both low and high soil nutrient levels with or without root intermingling. The magnitude of N transfer was relatively high (representing 4% of donor plant N) given the lack of N2 fixation. Receiver plants forming ectomycorrhizas or cluster roots were more enriched compared with AM-only plants. We demonstrate N transfer between plants of contrasting nutrient-acquisition strategies, and a preferential enrichment of cluster-rooted and EM plants compared with AM plants. Nutrient exchanges among plants are potentially important in promoting plant coexistence in nutrient-poor soils. © 2014 John Wiley & Sons Ltd.

Planned versus Unplanned Contrasts: Exactly Why Planned Contrasts Tend To Have More Power against Type II Error.

ERIC Educational Resources Information Center

Wang, Lin

The literature is reviewed regarding the difference between planned contrasts, OVA and unplanned contrasts. The relationship between statistical power of a test method and Type I, Type II error rates is first explored to provide a framework for the discussion. The concepts and formulation of contrast, orthogonal and non-orthogonal contrasts are…

Clinical study of contrast-enhanced digital mammography and the evaluation of blood and lymphatic microvessel density

PubMed Central

Cruz-Bastida, Juan P; Rosado-Méndez, Iván M; Villaseñor-Navarro, Yolanda; Pérez-Ponce, Héctor; Galván, Héctor A; Trujillo-Zamudio, Flavio E; Sánchez-Suárez, Patricia; Benítez-Bribiesca, Luis

2016-01-01

Objective: To correlate image parameters in contrast-enhanced digital mammography (CEDM) with blood and lymphatic microvessel density (MVD). Methods: 18 Breast Imaging-Reporting and Data System (BI-RADS)-4 to BI-RADS-5 patients were subjected to CEDM. Craniocaudal views were acquired, two views (low and high energy) before iodine contrast medium (CM) injection and four views (high energy) 1–5 min afterwards. Processing included registration and two subtraction modalities, traditional single-energy temporal (high-energy) and “dual-energy temporal with a matrix”, proposed to improve lesion conspicuity. Images were calibrated into iodine thickness, and iodine uptake, contrast, time–intensity and time–contrast kinetic curves were quantified. Image indicators were compared with MVD evaluated by anti-CD105 and anti-podoplanin (D2-40) immunohistochemistry. Results: 11 lesions were cancerous and 7 were benign. CEDM subtraction strongly increased conspicuity of lesions enhanced by iodine uptake. A strong correlation was observed between lymphatic vessels and blood vessels; all benign lesions had <30 blood microvessels per field, and all cancers had more than this value. MVD showed no correlation with iodine uptake, nor with contrast. The most frequent curve was early uptake followed by plateau for uptake and contrast in benign and malignant lesions. The positive-predictive value of uptake dynamics was 73% and that of contrast was 64%. Conclusion: CEDM increased lesion visibility and showed additional features compared with conventional mammography. Lack of correlation between image parameters and MVD is probably due to tumour tissue heterogeneity, mammography projective nature and/or dependence of extracellular iodine irrigation on tissue composition. Advances in knowledge: Quantitative analysis of CEDM images was performed. Image parameters and MVD showed no correlation. Probably, this is indication of the complex dependence of CM perfusion on tumour

Contrast-enhanced ultrasound (CEUS) in blunt abdominal trauma

PubMed Central

Piccolo, Claudia Lucia; Galluzzo, Michele; Ianniello, Stefania; Sessa, Barbara; Trinci, Margherita

2016-01-01

Baseline ultrasound is essential in the early assessment of patients with a huge haemoperitoneum undergoing an immediate abdominal surgery; nevertheless, even with a highly experienced operator, it is not sufficient to exclude parenchymal injuries. More recently, a new ultrasound technique using second generation contrast agents, named contrast-enhanced ultrasound (CEUS) has been developed. This technique allows all the vascular phase to be performed in real time, increasing ultrasound capability to detect parenchymal injuries, enhancing some qualitative findings, such as lesion extension, margins and its relationship with capsule and vessels. CEUS has been demonstrated to be almost as sensitive as contrast-enhanced CT in the detection of traumatic injuries in patients with low-energy isolated abdominal trauma, with levels of sensitivity and specificity up to 95%. Several studies demonstrated its ability to detect lesions occurring in the liver, spleen, pancreas and kidneys and also to recognize active bleeding as hyperechoic bands appearing as round or oval spots of variable size. Its role seems to be really relevant in paediatric patients, thus avoiding a routine exposure to ionizing radiation. Nevertheless, CEUS is strongly operator dependent, and it has some limitations, such as the cost of contrast media, lack of panoramicity, the difficulty to explore some deep regions and the poor ability to detect injuries to the urinary tract. On the other hand, it is timesaving, and it has several advantages, such as its portability, the safety of contrast agent, the lack to ionizing radiation exposure and therefore its repeatability, which allows follow-up of those traumas managed conservatively, especially in cases of fertile females and paediatric patients. PMID:26607647

Quantifying the Economic and Grid Reliability Impacts of Improved Wind Power Forecasting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Qin; Martinez-Anido, Carlo Brancucci; Wu, Hongyu

Wind power forecasting is an important tool in power system operations to address variability and uncertainty. Accurately doing so is important to reducing the occurrence and length of curtailment, enhancing market efficiency, and improving the operational reliability of the bulk power system. This research quantifies the value of wind power forecasting improvements in the IEEE 118-bus test system as modified to emulate the generation mixes of Midcontinent, California, and New England independent system operator balancing authority areas. To measure the economic value, a commercially available production cost modeling tool was used to simulate the multi-timescale unit commitment (UC) and economicmore » dispatch process for calculating the cost savings and curtailment reductions. To measure the reliability improvements, an in-house tool, FESTIV, was used to calculate the system's area control error and the North American Electric Reliability Corporation Control Performance Standard 2. The approach allowed scientific reproducibility of results and cross-validation of the tools. A total of 270 scenarios were evaluated to accommodate the variation of three factors: generation mix, wind penetration level, and wind fore-casting improvements. The modified IEEE 118-bus systems utilized 1 year of data at multiple timescales, including the day-ahead UC, 4-hour-ahead UC, and 5-min real-time dispatch. The value of improved wind power forecasting was found to be strongly tied to the conventional generation mix, existence of energy storage devices, and the penetration level of wind energy. The simulation results demonstrate that wind power forecasting brings clear benefits to power system operations.« less

Real-time Monitoring of Radiofrequency Ablation and Postablation Assessment: Accuracy of Contrast-enhanced US in Experimental Rat Liver Model

PubMed Central

Wu, Hanping; Wilkins, Luke R.; Ziats, Nicholas P.; Haaga, John R.

2014-01-01

Purpose To examine the accuracy of the unenhanced zone at contrast material–enhanced ultrasonography (US) in predicting coagulative necrosis during and 21 days after radiofrequency (RF) ablation by using radiologic-pathologic comparison. Materials and methods Animal studies were approved by the Institutional Animal Care and Use Committee. The livers of 28 rats underwent US-guided RF ablation. In four animals, contrast-enhanced US was performed during ablation and 2 hours and 2, 7, 14, and 21 days after ablation. The unenhanced zone area on US images was measured. DiI-labeled microbubbles were administered during ablation at 2, 4, and 6 minutes or at 2 hours and 2, 7, 14, and 21 days after ablation in the remaining 24 animals (n = 3 at each time point). One minute later, the animal was euthanized, and the ablated liver was harvested. Tissue samples were imaged to quantify total fluorescence, and NADH staining was performed on the same slice. Hematoxylin-eosin staining was also performed. The findings on fluorescence images, NADH-stained images, and hematoxylin-eosin–stained images were compared. The areas of DiI bubble–negative zones, NADH-negative zones, and lightly NADH-staining zones were measured. Data were analyzed by using one-way analysis of variance. Results The area of the unenhanced zone on contrast-enhanced US images increased during RF ablation and reached a maximum within 2 days after ablation. At histopathologic examination, a transition zone manifested adjacent to the coagulation zone until 2 days after ablation. The DiI-bubble negative zone on fluorescence images and the damaged zone (transition zone plus coagulation zone) on NADH-stained images increased rapidly within 2 hours after ablation, then slowly reached the maximum on day 2. The ratios of the mean areas of these two zones at hour 2 to those at day 2 were 94.6% and 95.6%, respectively. High uniformity between the damaged zone on NADH-stained images and the DiI bubble–negative zone on

Comparison of Low-Dose Higher-Relaxivity and Standard-Dose Lower-Relaxivity Contrast Media for Delayed-Enhancement MRI: A Blinded Randomized Crossover Study.

PubMed

Cheong, Benjamin Y C; Duran, Cihan; Preventza, Ourania A; Muthupillai, Raja

2015-09-01

The gadolinium-based MRI contrast agent gadobenate dimeglumine has nearly twice the MR relaxivity of gadopentetate dimeglumine at 1.5 T. The purpose of this study was to determine whether a lower dose (0.1 mmol/kg) of gadobenate dimeglumine can be used to obtain delayed-enhancement MR images comparable to those obtained with a standard dose (0.2 mmol/kg) of gadopentetate dimeglumine. In this blinded randomized crossover study, 20 patients with known myocardial infarction underwent two separate delayed-enhancement MRI examinations after receiving 0.1 mmol/kg gadobenate dimeglumine and 0.2 mmol/kg gadopentetate dimeglumine (random administration). The conspicuity of lesion enhancement 5, 10, and 20 minutes after contrast administration was quantified as relative enhancement ratio (RER). With either gadolinium-based contrast agent, damaged myocardium had higher signal intensity than normal remote myocardium (RER > 4) on delayed-enhancement MR images, and the blood RER declined over time after contrast administration. The blood RER was not significantly higher for gadobenate dimeglumine than for gadopentetate dimeglumine at 5 and 10 minutes. Nevertheless, there was a larger reduction in blood RER for gadobenate dimeglumine than for gadopentetate dimeglumine between 5 and 10 minutes and between 10 and 20 minutes. The volumes of enhancement were similar for gadobenate dimeglumine (13.6 ± 8.8 cm(3)) and gadopentetate dimeglumine (13.5 ± 8.9 cm(3)) (p = 0.98). The mean difference in Bland-Altman analysis for delayed-enhancement volume between the agents was 0.1 cm(3). Qualitatively and quantitatively, delayed-enhancement MR images of ischemic myocardium obtained with 0.1 mmol/kg gadobenate dimeglumine are comparable to those obtained with 0.2 mmol/kg gadopentetate dimeglumine 5, 10, and 20 minutes after contrast administration.

Comparison of epicardial adipose tissue radiodensity threshold between contrast and non-contrast enhanced computed tomography scans: A cohort study of derivation and validation.

PubMed

Xu, Lingyu; Xu, Yuancheng; Coulden, Richard; Sonnex, Emer; Hrybouski, Stanislau; Paterson, Ian; Butler, Craig

2018-05-11

Epicardial adipose tissue (EAT) volume derived from contrast enhanced (CE) computed tomography (CT) scans is not well validated. We aim to establish a reliable threshold to accurately quantify EAT volume from CE datasets. We analyzed EAT volume on paired non-contrast (NC) and CE datasets from 25 patients to derive appropriate Hounsfield (HU) cutpoints to equalize two EAT volume estimates. The gold standard threshold (-190HU, -30HU) was used to assess EAT volume on NC datasets. For CE datasets, EAT volumes were estimated using three previously reported thresholds: (-190HU, -30HU), (-190HU, -15HU), (-175HU, -15HU) and were analyzed by a semi-automated 3D Fat analysis software. Subsequently, we applied a threshold correction to (-190HU, -30HU) based on mean differences in radiodensity between NC and CE images (ΔEATrd = CE radiodensity - NC radiodensity). We then validated our findings on EAT threshold in 21 additional patients with paired CT datasets. EAT volume from CE datasets using previously published thresholds consistently underestimated EAT volume from NC dataset standard by a magnitude of 8.2%-19.1%. Using our corrected threshold (-190HU, -3HU) in CE datasets yielded statistically identical EAT volume to NC EAT volume in the validation cohort (186.1 ± 80.3 vs. 185.5 ± 80.1 cm 3 , Δ = 0.6 cm 3 , 0.3%, p = 0.374). Estimating EAT volume from contrast enhanced CT scans using a corrected threshold of -190HU, -3HU provided excellent agreement with EAT volume from non-contrast CT scans using a standard threshold of -190HU, -30HU. Copyright © 2018. Published by Elsevier B.V.

A Feasibility Study to Determine Whether Clinical Contrast Enhanced Magnetic Resonance Imaging can Detect Increased Bladder Permeability in Patients with Interstitial Cystitis.

PubMed

Towner, Rheal A; Wisniewski, Amy B; Wu, Dee H; Van Gordon, Samuel B; Smith, Nataliya; North, Justin C; McElhaney, Rayburt; Aston, Christopher E; Shobeiri, S Abbas; Kropp, Bradley P; Greenwood-Van Meerveld, Beverley; Hurst, Robert E

2016-03-01

Interstitial cystitis/bladder pain syndrome is a bladder pain disorder associated with voiding symptomatology and other systemic chronic pain disorders. Currently diagnosing interstitial cystitis/bladder pain syndrome is complicated as patients present with a wide range of symptoms, physical examination findings and clinical test responses. One hypothesis is that interstitial cystitis symptoms arise from increased bladder permeability to urine solutes. This study establishes the feasibility of using contrast enhanced magnetic resonance imaging to quantify bladder permeability in patients with interstitial cystitis. Permeability alterations in bladder urothelium were assessed by intravesical administration of the magnetic resonance imaging contrast agent Gd-DTPA (Gd-diethylenetriaminepentaacetic acid) in a small cohort of patients. Magnetic resonance imaging signal intensity in patient and control bladders was compared regionally and for entire bladders. Quantitative assessment of magnetic resonance imaging signal intensity indicated a significant increase in signal intensity in anterior bladder regions compared to posterior regions in patients with interstitial cystitis (p <0.01) and significant increases in signal intensity in anterior bladder regions (p <0.001). Kurtosis (shape of probability distribution) and skewness (measure of probability distribution asymmetry) were associated with contrast enhancement in total bladders in patients with interstitial cystitis vs controls (p <0.05). Regarding symptomatology interstitial cystitis cases differed significantly from controls on the SF-36®, PUF (Pelvic Pain and Urgency/Frequency) and ICPI (Interstitial Cystitis Problem Index) questionnaires with no overlap in the score range in each group. ICSI (Interstitial Cystitis Symptom Index) differed significantly but with a slight overlap in the range of scores. Data suggest that contrast enhanced magnetic resonance imaging provides an objective, quantifiable measurement

Feature and contrast enhancement of mammographic image based on multiscale analysis and morphology.

PubMed

Wu, Shibin; Yu, Shaode; Yang, Yuhan; Xie, Yaoqin

2013-01-01

A new algorithm for feature and contrast enhancement of mammographic images is proposed in this paper. The approach bases on multiscale transform and mathematical morphology. First of all, the Laplacian Gaussian pyramid operator is applied to transform the mammography into different scale subband images. In addition, the detail or high frequency subimages are equalized by contrast limited adaptive histogram equalization (CLAHE) and low-pass subimages are processed by mathematical morphology. Finally, the enhanced image of feature and contrast is reconstructed from the Laplacian Gaussian pyramid coefficients modified at one or more levels by contrast limited adaptive histogram equalization and mathematical morphology, respectively. The enhanced image is processed by global nonlinear operator. The experimental results show that the presented algorithm is effective for feature and contrast enhancement of mammogram. The performance evaluation of the proposed algorithm is measured by contrast evaluation criterion for image, signal-noise-ratio (SNR), and contrast improvement index (CII).

Feature and Contrast Enhancement of Mammographic Image Based on Multiscale Analysis and Morphology

PubMed Central

Wu, Shibin; Xie, Yaoqin

2013-01-01

A new algorithm for feature and contrast enhancement of mammographic images is proposed in this paper. The approach bases on multiscale transform and mathematical morphology. First of all, the Laplacian Gaussian pyramid operator is applied to transform the mammography into different scale subband images. In addition, the detail or high frequency subimages are equalized by contrast limited adaptive histogram equalization (CLAHE) and low-pass subimages are processed by mathematical morphology. Finally, the enhanced image of feature and contrast is reconstructed from the Laplacian Gaussian pyramid coefficients modified at one or more levels by contrast limited adaptive histogram equalization and mathematical morphology, respectively. The enhanced image is processed by global nonlinear operator. The experimental results show that the presented algorithm is effective for feature and contrast enhancement of mammogram. The performance evaluation of the proposed algorithm is measured by contrast evaluation criterion for image, signal-noise-ratio (SNR), and contrast improvement index (CII). PMID:24416072

Contrast-Enhanced C-arm Computed Tomography Imaging of Myocardial Infarction in the Interventional Suite

PubMed Central

Girard, Erin E; Al-Ahmad, Amin; Rosenberg, Jarrett; Luong, Richard; Moore, Teri; Lauritsch, Günter; Chan, Frandics; Lee, David P.; Fahrig, Rebecca

2014-01-01

Objectives Cardiac C-arm CT uses a standard C-arm fluoroscopy system rotating around the patient to provide CT-like images during interventional procedures without moving the patient to a conventional CT scanner. We hypothesize that C-arm computed tomography (CT) can be used to visualize and quantify the size of perfusion defects and late enhancement resulting from a myocardial infarction (MI) using contrast enhanced techniques similar to previous CT and magnetic resonance imaging studies. Materials and Methods A balloon occlusion followed by reperfusion in a coronary artery was used to study acute and subacute MI in 12 swine. ECG-gated C-arm CT images were acquired the day of infarct creation (n=6) or 4 weeks after infarct creation (n = 6). Images were acquired immediately following contrast injection, then at 1 minute, and every 5 minutes up to 30 minutes with no additional contrast. The volume of the infarct as measured on C-arm CT was compared against pathology. Results The volume of acute MI, visualized as a combined region of hyperenhancement with a hypoenhanced core, correlated well with pathologic staining (concordance correlation = 0.89, p<0.0001, mean difference = 0.67±2.98 cm3). The volume of subacute MI, visualized as a region of hyperenhancement, correlated well with pathologic staining at imaging times 5–15 minutes following contrast injection (concordance correlation = 0.82, p<.001, mean difference = −0.64±1.94 cm3). Conclusions C-arm CT visualization of acute and subacute myocardial infarction is possible in a porcine model but improvement in the imaging technique is important before clinical use. Visualization of MI in the catheterization lab may be possible and could provide 3D images for guidance during interventional procedures. PMID:25635589

Uniform enhancement of optical micro-angiography images using Rayleigh contrast-limited adaptive histogram equalization

PubMed Central

Yousefi, Siavash; Qin, Jia; Zhi, Zhongwei

2013-01-01

Optical microangiography is an imaging technology that is capable of providing detailed functional blood flow maps within microcirculatory tissue beds in vivo. Some practical issues however exist when displaying and quantifying the microcirculation that perfuses the scanned tissue volume. These issues include: (I) Probing light is subject to specular reflection when it shines onto sample. The unevenness of the tissue surface makes the light energy entering the tissue not uniform over the entire scanned tissue volume. (II) The biological tissue is heterogeneous in nature, meaning the scattering and absorption properties of tissue would attenuate the probe beam. These physical limitations can result in local contrast degradation and non-uniform micro-angiogram images. In this paper, we propose a post-processing method that uses Rayleigh contrast-limited adaptive histogram equalization to increase the contrast and improve the overall appearance and uniformity of optical micro-angiograms without saturating the vessel intensity and changing the physical meaning of the micro-angiograms. The qualitative and quantitative performance of the proposed method is compared with those of common histogram equalization and contrast enhancement methods. We demonstrate that the proposed method outperforms other existing approaches. The proposed method is not limited to optical microangiography and can be used in other image modalities such as photo-acoustic tomography and scanning laser confocal microscopy. PMID:23482880

Uniform enhancement of optical micro-angiography images using Rayleigh contrast-limited adaptive histogram equalization.

PubMed

Yousefi, Siavash; Qin, Jia; Zhi, Zhongwei; Wang, Ruikang K

2013-02-01

Optical microangiography is an imaging technology that is capable of providing detailed functional blood flow maps within microcirculatory tissue beds in vivo. Some practical issues however exist when displaying and quantifying the microcirculation that perfuses the scanned tissue volume. These issues include: (I) Probing light is subject to specular reflection when it shines onto sample. The unevenness of the tissue surface makes the light energy entering the tissue not uniform over the entire scanned tissue volume. (II) The biological tissue is heterogeneous in nature, meaning the scattering and absorption properties of tissue would attenuate the probe beam. These physical limitations can result in local contrast degradation and non-uniform micro-angiogram images. In this paper, we propose a post-processing method that uses Rayleigh contrast-limited adaptive histogram equalization to increase the contrast and improve the overall appearance and uniformity of optical micro-angiograms without saturating the vessel intensity and changing the physical meaning of the micro-angiograms. The qualitative and quantitative performance of the proposed method is compared with those of common histogram equalization and contrast enhancement methods. We demonstrate that the proposed method outperforms other existing approaches. The proposed method is not limited to optical microangiography and can be used in other image modalities such as photo-acoustic tomography and scanning laser confocal microscopy.

Improvements in Diagnostic Accuracy with Quantitative Dynamic Contrast-Enhanced MRI

DTIC Science & Technology

2011-12-01

Magnetic   Resonance   Imaging  during  the  Menstrual  Cylce:  Perfusion   Imaging  Signal   Enhanceent,  and  Influence  of...acquisition of quantitative images displaying the concentration of contrast media as well as MRI -detectable proton density. To date 21 patients have...truly  quantitative   images  of  a  dynamic  contrast-­‐enhanced  (DCE)   MRI  of  the

Evaluation of left ventricular scar identification from contrast enhanced magnetic resonance imaging for guidance of ventricular catheter ablation therapy

NASA Astrophysics Data System (ADS)

Rettmann, M. E.; Lehmann, H. I.; Johnson, S. B.; Packer, D. L.

2016-03-01

Patients with ventricular arrhythmias typically exhibit myocardial scarring, which is believed to be an important anatomic substrate for reentrant circuits, thereby making these regions a key target in catheter ablation therapy. In ablation therapy, a catheter is guided into the left ventricle and radiofrequency energy is delivered into the tissue to interrupt arrhythmic electrical pathways. Low bipolar voltage regions are typically localized during the procedure through point-by-point construction of an electroanatomic map by sampling the endocardial surface with the ablation catheter and are used as a surrogate for myocardial scar. This process is time consuming, requires significant skill, and has the potential to miss low voltage sites. This has led to efforts to quantify myocardial scar preoperatively using delayed, contrast-enhanced MRI. In this paper, we evaluate the utility of left ventricular scar identification from delayed contrast enhanced magnetic resonance imaging for guidance of catheter ablation of ventricular arrhythmias. Myocardial infarcts were created in three canines followed by a delayed, contrast enhanced MRI scan and electroanatomic mapping. The left ventricle and myocardial scar is segmented from preoperative MRI images and sampled points from the procedural electroanatomical map are registered to the segmented endocardial surface. Sampled points with low bipolar voltage points visually align with the segmented scar regions. This work demonstrates the potential utility of using preoperative delayed, enhanced MRI to identify myocardial scarring for guidance of ventricular catheter ablation therapy.

High-resolution contrast-enhanced optical coherence tomography in mice retinae

NASA Astrophysics Data System (ADS)

Sen, Debasish; SoRelle, Elliott D.; Liba, Orly; Dalal, Roopa; Paulus, Yannis M.; Kim, Tae-Wan; Moshfeghi, Darius M.; de la Zerda, Adam

2016-06-01

Optical coherence tomography (OCT) is a noninvasive interferometric imaging modality providing anatomical information at depths of millimeters and a resolution of micrometers. Conventional OCT images limit our knowledge to anatomical structures alone, without any contrast enhancement. Therefore, here we have, for the first time, optimized an OCT-based contrast-enhanced imaging system for imaging single cells and blood vessels in vivo inside the living mouse retina at subnanomolar sensitivity. We used bioconjugated gold nanorods (GNRs) as exogenous OCT contrast agents. Specifically, we used anti-mouse CD45 coated GNRs to label mouse leukocytes and mPEG-coated GNRs to determine sensitivity of GNR detection in vivo inside mice retinae. We corroborated OCT observations with hyperspectral dark-field microscopy of formalin-fixed histological sections. Our results show that mouse leukocytes that otherwise do not produce OCT contrast can be labeled with GNRs leading to significant OCT intensity equivalent to a 0.5 nM GNR solution. Furthermore, GNRs injected intravenously can be detected inside retinal blood vessels at a sensitivity of ˜0.5 nM, and GNR-labeled cells injected intravenously can be detected inside retinal capillaries by enhanced OCT contrast. We envision the unprecedented resolution and sensitivity of functionalized GNRs coupled with OCT to be adopted for longitudinal studies of retinal disorders.

An improved contrast enhancement algorithm for infrared images based on adaptive double plateaus histogram equalization

NASA Astrophysics Data System (ADS)

Li, Shuo; Jin, Weiqi; Li, Li; Li, Yiyang

2018-05-01

Infrared thermal images can reflect the thermal-radiation distribution of a particular scene. However, the contrast of the infrared images is usually low. Hence, it is generally necessary to enhance the contrast of infrared images in advance to facilitate subsequent recognition and analysis. Based on the adaptive double plateaus histogram equalization, this paper presents an improved contrast enhancement algorithm for infrared thermal images. In the proposed algorithm, the normalized coefficient of variation of the histogram, which characterizes the level of contrast enhancement, is introduced as feedback information to adjust the upper and lower plateau thresholds. The experiments on actual infrared images show that compared to the three typical contrast-enhancement algorithms, the proposed algorithm has better scene adaptability and yields better contrast-enhancement results for infrared images with more dark areas or a higher dynamic range. Hence, it has high application value in contrast enhancement, dynamic range compression, and digital detail enhancement for infrared thermal images.

Liver enhancement in healthy dogs after gadoxetic acid administration during dynamic contrast-enhanced magnetic resonance imaging.

PubMed

Borusewicz, P; Stańczyk, E; Kubiak, K; Spużak, J; Glińska-Suchocka, K; Jankowski, M; Nicpoń, J; Podgórski, P

2018-05-01

Dynamic contrast enhanced (DCE)-magnetic resonance imaging (MRI) consists of acquisition of native baseline images, followed by a series of acquisitions performed during and after administration of a contrast medium. DCE-MRI, in conjunction with hepatobiliary-specific contrast media, such as gadoxetic acid (GD-EOB-DTPA), allows for precise characterisation of the enhancement pattern of the hepatic parenchyma following administration of the contrast agent. The aim of the study was to assess the pattern of temporal resolution contrast enhancement of the hepatic parenchyma following administration of GD-EOB-DTPA and to determine the optimal time window for post-contrast assessment of the liver. The study was carried out on eight healthy beagle dogs. MRI was performed using a 1.5T scanner. The imaging protocol included T1 weighted (T1-W) gradient echo (GRE), T2 weighted (T2-W) turbo spin echo (TSE) and dynamic T1-W GRE sequences. The dynamic T1-W sequence was performed using single 10mm thick slices. Regions of interest (ROIs) were chosen and the signal intensity curves were calculated for quantitative image analysis. The mean time to peak for all dogs was 26min. The plateau phase lasted on average 21min. A gradual decrease in the signal intensity of the hepatic parenchyma was observed in all dogs. A DCE-MRI enhancement pattern of the hepatic parenchyma was evident in dogs following the administration of a GD-EOB-DTPA, establishing baseline data for an optimal time window between 26 and 41min after administration of the contrast agent. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hadamard-Encoded Multipulses for Contrast-Enhanced Ultrasound Imaging.

PubMed

Gong, Ping; Song, Pengfei; Chen, Shigao

2017-11-01

The development of contrast-enhanced ultrasound (CEUS) imaging offers great opportunities for new ultrasound clinical applications such as myocardial perfusion imaging and abdominal lesion characterization. In CEUS imaging, the contrast agents (i.e., microbubbles) are utilized to improve the contrast between blood and tissue based on their high nonlinearity under low ultrasound pressure. In this paper, we propose a new CEUS pulse sequence by combining Hadamard-encoded multipulses (HEM) with fundamental frequency bandpass filter (i.e., filter centered on transmit frequency). HEM consecutively emits multipulses encoded by a second-order Hadamard matrix in each of the two transmission events (i.e., pulse-echo events), as opposed to conventional CEUS methods which emit individual pulses in two separate transmission events (i.e., pulse inversion (PI), amplitude modulation (AM), and PIAM). In HEM imaging, the microbubble responses can be improved by the longer transmit pulse, and the tissue harmonics can be suppressed by the fundamental frequency filter, leading to significantly improved contrast-to-tissue ratio (CTR) and signal-to-noise ratio (SNR). In addition, the fast polarity change between consecutive coded pulse emissions excites strong nonlinear microbubble echoes, further enhancing the CEUS image quality. The spatial resolution of HEM image is compromised as compared to other microbubble imaging methods due to the longer transmit pulses and the lower imaging frequency (i.e., fundamental frequency). However, the resolution loss was shown to be negligible and could be offset by the significantly enhanced CTR, SNR, and penetration depth. These properties of HEM can potentially facilitate robust CEUS imaging for many clinical applications, especially for deep abdominal organs and heart.

Renal Perfusion in Scleroderma Patients Assessed by Microbubble-Based Contrast-Enhanced Ultrasound

PubMed Central

Kleinert, Stefan; Roll, Petra; Baumgaertner, Christian; Himsel, Andrea; Mueller, Adelheid; Fleck, Martin; Feuchtenberger, Martin; Jenett, Manfred; Tony, Hans-Peter

2012-01-01

Objectives: Renal damage is common in scleroderma. It can occur acutely or chronically. Renal reserve might already be impaired before it can be detected by laboratory findings. Microbubble-based contrast-enhanced ultrasound has been demonstrated to improve blood perfusion imaging in organs. Therefore, we conducted a study to assess renal perfusion in scleroderma patients utilizing this novel technique. Materials and Methodology: Microbubble-based contrast agent was infused and destroyed by using high mechanical index by Siemens Sequoia (curved array, 4.5 MHz). Replenishment was recorded for 8 seconds. Regions of interests (ROI) were analyzed in renal parenchyma, interlobular artery and renal pyramid with quantitative contrast software (CUSQ 1.4, Siemens Acuson, Mountain View, California). Time to maximal Enhancement (TmE), maximal enhancement (mE) and maximal enhancement relative to maximal enhancement of the interlobular artery (mE%A) were calculated for different ROIs. Results: There was a linear correlation between the time to maximal enhancement in the parenchyma and the glomerular filtration rate. However, the other parameters did not reveal significant differences between scleroderma patients and healthy controls. Conclusion: Renal perfusion of scleroderma patients including the glomerular filtration rate can be assessed using microbubble-based contrast media. PMID:22670165

Multifactorial Optimization of Contrast-Enhanced Nanofocus Computed Tomography for Quantitative Analysis of Neo-Tissue Formation in Tissue Engineering Constructs.

PubMed

Sonnaert, Maarten; Kerckhofs, Greet; Papantoniou, Ioannis; Van Vlierberghe, Sandra; Boterberg, Veerle; Dubruel, Peter; Luyten, Frank P; Schrooten, Jan; Geris, Liesbet

2015-01-01

To progress the fields of tissue engineering (TE) and regenerative medicine, development of quantitative methods for non-invasive three dimensional characterization of engineered constructs (i.e. cells/tissue combined with scaffolds) becomes essential. In this study, we have defined the most optimal staining conditions for contrast-enhanced nanofocus computed tomography for three dimensional visualization and quantitative analysis of in vitro engineered neo-tissue (i.e. extracellular matrix containing cells) in perfusion bioreactor-developed Ti6Al4V constructs. A fractional factorial 'design of experiments' approach was used to elucidate the influence of the staining time and concentration of two contrast agents (Hexabrix and phosphotungstic acid) and the neo-tissue volume on the image contrast and dataset quality. Additionally, the neo-tissue shrinkage that was induced by phosphotungstic acid staining was quantified to determine the operating window within which this contrast agent can be accurately applied. For Hexabrix the staining concentration was the main parameter influencing image contrast and dataset quality. Using phosphotungstic acid the staining concentration had a significant influence on the image contrast while both staining concentration and neo-tissue volume had an influence on the dataset quality. The use of high concentrations of phosphotungstic acid did however introduce significant shrinkage of the neo-tissue indicating that, despite sub-optimal image contrast, low concentrations of this staining agent should be used to enable quantitative analysis. To conclude, design of experiments allowed us to define the most optimal staining conditions for contrast-enhanced nanofocus computed tomography to be used as a routine screening tool of neo-tissue formation in Ti6Al4V constructs, transforming it into a robust three dimensional quality control methodology.

Low-temperature thermoelectric power factor enhancement by controlling nanoparticle size distribution.

PubMed

Zebarjadi, Mona; Esfarjani, Keivan; Bian, Zhixi; Shakouri, Ali

2011-01-12

Coherent potential approximation is used to study the effect of adding doped spherical nanoparticles inside a host matrix on the thermoelectric properties. This takes into account electron multiple scatterings that are important in samples with relatively high volume fraction of nanoparticles (>1%). We show that with large fraction of uniform small size nanoparticles (∼1 nm), the power factor can be enhanced significantly. The improvement could be large (up to 450% for GaAs) especially at low temperatures when the mobility is limited by impurity or nanoparticle scattering. The advantage of doping via embedded nanoparticles compared to the conventional shallow impurities is quantified. At the optimum thermoelectric power factor, the electrical conductivity of the nanoparticle-doped material is larger than that of impurity-doped one at the studied temperature range (50-500 K) whereas the Seebeck coefficient of the nanoparticle doped material is enhanced only at low temperatures (∼50 K).

Diagnosis of breast masses from dynamic contrast-enhanced and diffusion-weighted MR: a machine learning approach.

PubMed

Cai, Hongmin; Peng, Yanxia; Ou, Caiwen; Chen, Minsheng; Li, Li

2014-01-01

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is increasingly used for breast cancer diagnosis as supplementary to conventional imaging techniques. Combining of diffusion-weighted imaging (DWI) of morphology and kinetic features from DCE-MRI to improve the discrimination power of malignant from benign breast masses is rarely reported. The study comprised of 234 female patients with 85 benign and 149 malignant lesions. Four distinct groups of features, coupling with pathological tests, were estimated to comprehensively characterize the pictorial properties of each lesion, which was obtained by a semi-automated segmentation method. Classical machine learning scheme including feature subset selection and various classification schemes were employed to build prognostic model, which served as a foundation for evaluating the combined effects of the multi-sided features for predicting of the types of lesions. Various measurements including cross validation and receiver operating characteristics were used to quantify the diagnostic performances of each feature as well as their combination. Seven features were all found to be statistically different between the malignant and the benign groups and their combination has achieved the highest classification accuracy. The seven features include one pathological variable of age, one morphological variable of slope, three texture features of entropy, inverse difference and information correlation, one kinetic feature of SER and one DWI feature of apparent diffusion coefficient (ADC). Together with the selected diagnostic features, various classical classification schemes were used to test their discrimination power through cross validation scheme. The averaged measurements of sensitivity, specificity, AUC and accuracy are 0.85, 0.89, 90.9% and 0.93, respectively. Multi-sided variables which characterize the morphological, kinetic, pathological properties and DWI measurement of ADC can dramatically improve the

Contrast-enhanced ultrasound in diagnosis of gallbladder adenoma.

PubMed

Yuan, Hai-Xia; Cao, Jia-Ying; Kong, Wen-Tao; Xia, Han-Sheng; Wang, Xi; Wang, Wen-Ping

2015-04-01

Gallbladder adenoma is a pre-cancerous neoplasm and needs surgical resection. It is difficult to differentiate adenoma from other gallbladder polyps using imaging examinations. The study aimed to illustrate characteristics of contrast-enhanced ultrasound (CEUS) and its diagnostic value in gallbladder adenoma. Thirty-seven patients with 39 gallbladder adenomatoid lesions (maximal diameter ≥10 mm and without metastasis) were enrolled in this study. Lesion appearances in conventional ultrasound and CEUS were documented. The imaging features were compared individually among gallbladder cholesterol polyp, gallbladder adenoma and malignant lesion. Adenoma lesions showed iso-echogenicity in ultrasound, and an eccentric enhancement pattern, "fast-in and synchronous-out" contrast enhancement pattern and homogeneous at peak-time enhancement in CEUS. The homogenicity at peak-time enhancement showed the highest diagnostic ability in differentiating gallbladder adenoma from cholesterol polyps. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy and Youden index were 100%, 90.9%, 92.9%, 100%, 95.8% and 0.91, respectively. The characteristic of continuous gallbladder wall shown by CEUS had the highest diagnostic ability in differentiating adenoma from malignant lesion (100%, 86.7%, 86.7%, 100%, 92.9% and 0.87, respectively). The characteristic of the eccentric enhancement pattern had the highest diagnostic ability in differentiating adenoma from cholesterol polyp and malignant lesion, with corresponding indices of 69.2%, 88.5%, 75.0%, 85.2%, 82.1% and 0.58, respectively. CEUS is valuable in differentiating gallbladder adenoma from other gallbladder polyps (≥10 mm in diameter). Homogeneous echogenicity on peak-time enhancement, a continuous gallbladder wall, and the eccentric enhancement pattern are important indicators of gallbladder adenoma on CEUS.

A Glossy Simultaneous Contrast: Conjoint Measurements of Gloss and Lightness

PubMed Central

Mamassian, Pascal

2017-01-01

Interactions between the albedo and the gloss on a surface are commonplace. Darker surfaces are perceived glossier (contrast gloss) than lighter surfaces and darker backgrounds can enhance perceived lightness of surfaces. We used maximum likelihood conjoint measurements to simultaneously quantify the strength of those effects. We quantified the extent to which albedo can influence perceived gloss and physical gloss can influence perceived lightness. We modeled the contribution of lightness and gloss and found that increasing lightness reduced perceived gloss by about 32% whereas gloss had a much weaker influence on perceived lightness of about 12%. Moreover, we also investigated how different backgrounds contribute to the perception of lightness and gloss of a surface placed in front. We found that a glossy background reduces slightly perceived lightness of the center and simultaneously enhances its perceived gloss. Lighter backgrounds reduce perceived gloss and perceived lightness. Conjoint measurements lead us to a better understanding of the contextual effects in gloss and lightness perception. Not only do we confirm the importance of contrast in gloss perception and the reduction of the simultaneous contrast with glossy backgrounds, but we also quantify precisely the strength of those effects. PMID:28203352

Three-dimensional visualisation of the internal anatomy of the sparrowhawk (Accipiter nisus) forelimb using contrast-enhanced micro-computed tomography.

PubMed

Bribiesca-Contreras, Fernanda; Sellers, William I

2017-01-01

Gross dissection is a widespread method for studying animal anatomy, despite being highly destructive and time-consuming. X-ray computed tomography (CT) has been shown to be a non-destructive alternative for studying anatomical structures. However, in the past it has been limited to only being able to visualise mineralised tissues. In recent years, morphologists have started to use traditional X-ray contrast agents to allow the visualisation of soft tissue elements in the CT context. The aim of this project is to assess the ability of contrast-enhanced micro-CT (μCT) to construct a three-dimensional (3D) model of the musculoskeletal system of the bird wing and to quantify muscle geometry and any systematic changes due to shrinkage. We expect that this reconstruction can be used as an anatomical guide to the sparrowhawk wing musculature and form the basis of further biomechanical analysis of flight. A 3% iodine-buffered formalin solution with a 25-day staining period was used to visualise the wing myology of the sparrowhawk ( Accipiter nisus ). μCT scans of the wing were taken over the staining period until full penetration of the forelimb musculature by iodine was reached. A 3D model was reconstructed by manually segmenting out the individual elements of the avian wing using 3D visualisation software. Different patterns of contrast were observed over the duration of the staining treatment with the best results occurring after 25 days of staining. Staining made it possible to visualise and identify different elements of the soft tissue of the wing. Finally, a 3D reconstruction of the musculoskeletal system of the sparrowhawk wing is presented and numerical data of muscle geometry is compared to values obtained by dissection. Contrast-enhanced μCT allows the visualisation and identification of the wing myology of birds, including the smaller muscles in the hand, and provides a non-destructive way for quantifying muscle volume with an accuracy of 96.2%. By

Contrast-enhanced ultrasound in diagnosis and characterization of focal hepatic lesions.

PubMed

Molins, Inés Gómez; Font, Juan Manuel Fernández; Alvaro, Juan Carrero; Navarro, Jose Luís Lledó; Gil, Marta Fernández; Rodríguez, Conrado M Fernández

2010-12-28

The extensive use of imaging techniques in differential diagnosis of abdominal conditions and screening of hepatocellular carcinoma in patients with chronic hepatic diseases, has led to an important increase in identification of focal liver lesions. The development of contrast-enhanced ultrasound (CEUS) opens a new window in the diagnosis and follow-up of these lesions. This technique offers obvious advantages over the computed tomography and magnetic resonance, without a decrease in its sensitivity and specificity. The new second generation contrast agents, due to their intravascular distribution, allow a continuous evaluation of the enhancement pattern, which is crucial in characterization of liver lesions. The dual blood supply in the liver shows three different phases, namely arterial, portal and late phases. The enhancement during portal and late phases can give important information about the lesion's behavior. Each liver lesion has a different enhancement pattern that makes possible an accurate approach to their diagnosis. The role of emerging techniques as a contrast-enhanced three-dimensional US is also discussed. In this article, the advantages, indications and technique employed during CEUS and the different enhancement patterns of most benign and malignant focal liver lesions are discussed.

Contrast-enhanced ultrasound in diagnosis and characterization of focal hepatic lesions

PubMed Central

Molins, Inés Gómez; Font, Juan Manuel Fernández; Álvaro, Juan Carrero; Navarro, Jose Luís Lledó; Gil, Marta Fernández; Rodríguez, Conrado M Fernández

2010-01-01

The extensive use of imaging techniques in differential diagnosis of abdominal conditions and screening of hepatocellular carcinoma in patients with chronic hepatic diseases, has led to an important increase in identification of focal liver lesions. The development of contrast-enhanced ultrasound (CEUS) opens a new window in the diagnosis and follow-up of these lesions. This technique offers obvious advantages over the computed tomography and magnetic resonance, without a decrease in its sensitivity and specificity. The new second generation contrast agents, due to their intravascular distribution, allow a continuous evaluation of the enhancement pattern, which is crucial in characterization of liver lesions. The dual blood supply in the liver shows three different phases, namely arterial, portal and late phases. The enhancement during portal and late phases can give important information about the lesion’s behavior. Each liver lesion has a different enhancement pattern that makes possible an accurate approach to their diagnosis. The role of emerging techniques as a contrast-enhanced three-dimensional US is also discussed. In this article, the advantages, indications and technique employed during CEUS and the different enhancement patterns of most benign and malignant focal liver lesions are discussed. PMID:21225000

Adaptive image contrast enhancement using generalizations of histogram equalization.

PubMed

Stark, J A

2000-01-01

This paper proposes a scheme for adaptive image-contrast enhancement based on a generalization of histogram equalization (HE). HE is a useful technique for improving image contrast, but its effect is too severe for many purposes. However, dramatically different results can be obtained with relatively minor modifications. A concise description of adaptive HE is set out, and this framework is used in a discussion of past suggestions for variations on HE. A key feature of this formalism is a "cumulation function," which is used to generate a grey level mapping from the local histogram. By choosing alternative forms of cumulation function one can achieve a wide variety of effects. A specific form is proposed. Through the variation of one or two parameters, the resulting process can produce a range of degrees of contrast enhancement, at one extreme leaving the image unchanged, at another yielding full adaptive equalization.

Quantifying CO2 Emissions from Individual Power Plants using OCO-2 Observations

NASA Astrophysics Data System (ADS)

Nassar, R.; Hill, T. G.; McLinden, C. A.; Wunch, D.; Jones, D. B. A.; Crisp, D.

2017-12-01

In order to better manage anthropogenic CO2 emissions, improved methods of quantifying emissions are needed at all spatial scales from the national level down to the facility level. Although the Orbiting Carbon Observatory 2 (OCO-2) satellite was not designed for monitoring power plant emissions, we show that in select cases, CO2 observations from OCO-2 can be used to quantify daily CO2 emissions from individual mid- to large-sized coal power plants by fitting the data to plume model simulations. Emission estimates for US power plants are within 1-13% of reported daily emission values enabling application of the approach to international sites that lack detailed emission information. These results affirm that a constellation of future CO2 imaging satellites, optimized for point sources, could be used for the Monitoring, Reporting and Verification (MRV) of CO2 emissions from individual power plants to support the implementation of climate policies.

Perfusion quantification in contrast-enhanced ultrasound (CEUS)--ready for research projects and routine clinical use.

PubMed

Tranquart, F; Mercier, L; Frinking, P; Gaud, E; Arditi, M

2012-07-01

With contrast-enhanced ultrasound (CEUS) now established as a valuable imaging modality for many applications, a more specific demand has recently emerged for quantifying perfusion and using measured parameters as objective indicators for various disease states. However, CEUS perfusion quantification remains challenging and is not well integrated in daily clinical practice. The development of VueBox™ alleviates existing limitations and enables quantification in a standardized way. VueBox™ operates as an off-line software application, after dynamic contrast-enhanced ultrasound (DCE-US) is performed. It enables linearization of DICOM clips, assessment of perfusion using patented curve-fitting models, and generation of parametric images by synthesizing perfusion information at the pixel level using color coding. VueBox™ is compatible with most of the available ultrasound platforms (nonlinear contrast-enabled), has the ability to process both bolus and disruption-replenishment kinetics loops, allows analysis results and their context to be saved, and generates analysis reports automatically. Specific features have been added to VueBox™, such as fully automatic in-plane motion compensation and an easy-to-use clip editor. Processing time has been reduced as a result of parallel programming optimized for multi-core processors. A long list of perfusion parameters is available for each of the two administration modes to address all possible demands currently reported in the literature for diagnosis or treatment monitoring. In conclusion, VueBox™ is a valid and robust quantification tool to be used for standardizing perfusion quantification and to improve the reproducibility of results across centers. © Georg Thieme Verlag KG Stuttgart · New York.

Adaptive windowing in contrast-enhanced intravascular ultrasound imaging

PubMed Central

Lindsey, Brooks D.; Martin, K. Heath; Jiang, Xiaoning; Dayton, Paul A.

2016-01-01

Intravascular ultrasound (IVUS) is one of the most commonly-used interventional imaging techniques and has seen recent innovations which attempt to characterize the risk posed by atherosclerotic plaques. One such development is the use of microbubble contrast agents to image vasa vasorum, fine vessels which supply oxygen and nutrients to the walls of coronary arteries and typically have diameters less than 200 µm. The degree of vasa vasorum neovascularization within plaques is positively correlated with plaque vulnerability. Having recently presented a prototype dual-frequency transducer for contrast agent-specific intravascular imaging, here we describe signal processing approaches based on minimum variance (MV) beamforming and the phase coherence factor (PCF) for improving the spatial resolution and contrast-to-tissue ratio (CTR) in IVUS imaging. These approaches are examined through simulations, phantom studies, ex vivo studies in porcine arteries, and in vivo studies in chicken embryos. In phantom studies, PCF processing improved CTR by a mean of 4.2 dB, while combined MV and PCF processing improved spatial resolution by 41.7%. Improvements of 2.2 dB in CTR and 37.2% in resolution were observed in vivo. Applying these processing strategies can enhance image quality in conventional B-mode IVUS or in contrast-enhanced IVUS, where signal-to-noise ratio is relatively low and resolution is at a premium. PMID:27161022

Adaptive windowing in contrast-enhanced intravascular ultrasound imaging.

PubMed

Lindsey, Brooks D; Martin, K Heath; Jiang, Xiaoning; Dayton, Paul A

2016-08-01

Intravascular ultrasound (IVUS) is one of the most commonly-used interventional imaging techniques and has seen recent innovations which attempt to characterize the risk posed by atherosclerotic plaques. One such development is the use of microbubble contrast agents to image vasa vasorum, fine vessels which supply oxygen and nutrients to the walls of coronary arteries and typically have diameters less than 200μm. The degree of vasa vasorum neovascularization within plaques is positively correlated with plaque vulnerability. Having recently presented a prototype dual-frequency transducer for contrast agent-specific intravascular imaging, here we describe signal processing approaches based on minimum variance (MV) beamforming and the phase coherence factor (PCF) for improving the spatial resolution and contrast-to-tissue ratio (CTR) in IVUS imaging. These approaches are examined through simulations, phantom studies, ex vivo studies in porcine arteries, and in vivo studies in chicken embryos. In phantom studies, PCF processing improved CTR by a mean of 4.2dB, while combined MV and PCF processing improved spatial resolution by 41.7%. Improvements of 2.2dB in CTR and 37.2% in resolution were observed in vivo. Applying these processing strategies can enhance image quality in conventional B-mode IVUS or in contrast-enhanced IVUS, where signal-to-noise ratio is relatively low and resolution is at a premium. Copyright © 2016 Elsevier B.V. All rights reserved.

A review on brightness preserving contrast enhancement methods for digital image

NASA Astrophysics Data System (ADS)

Rahman, Md Arifur; Liu, Shilong; Li, Ruowei; Wu, Hongkun; Liu, San Chi; Jahan, Mahmuda Rawnak; Kwok, Ngaiming

2018-04-01

Image enhancement is an imperative step for many vision based applications. For image contrast enhancement, popular methods adopt the principle of spreading the captured intensities throughout the allowed dynamic range according to predefined distributions. However, these algorithms take little or no consideration into account of maintaining the mean brightness of the original scene, which is of paramount importance to carry the true scene illumination characteristics to the viewer. Though there have been significant amount of reviews on contrast enhancement methods published, updated review on overall brightness preserving image enhancement methods is still scarce. In this paper, a detailed survey is performed on those particular methods that specifically aims to maintain the overall scene illumination characteristics while enhancing the digital image.

Imaging of paediatric splenic injury with contrast-enhanced ultrasonography.

PubMed

Oldenburg, Anja; Hohmann, Joachim; Skrok, Jan; Albrecht, Thomas

2004-04-01

We report two children who sustained traumatic parenchymal splenic injury and were monitored with contrast-enhanced ultrasound (CEUS). In both cases, unenhanced US failed to diagnose splenic haematoma, but the injury was well demonstrated after injection of contrast agent. In one case agreement with CT was excellent; in the other, CT was not performed due to the comprehensive information provided by CEUS.

Morphological rational multi-scale algorithm for color contrast enhancement

NASA Astrophysics Data System (ADS)

Peregrina-Barreto, Hayde; Terol-Villalobos, Iván R.

2010-01-01

Contrast enhancement main goal consists on improving the image visual appearance but also it is used for providing a transformed image in order to segment it. In mathematical morphology several works have been derived from the framework theory for contrast enhancement proposed by Meyer and Serra. However, when working with images with a wide range of scene brightness, as for example when strong highlights and deep shadows appear in the same image, the proposed morphological methods do not allow the enhancement. In this work, a rational multi-scale method, which uses a class of morphological connected filters called filters by reconstruction, is proposed. Granulometry is used by finding the more accurate scales for filters and with the aim of avoiding the use of other little significant scales. The CIE-u'v'Y' space was used to introduce our results since it takes into account the Weber's Law and by avoiding the creation of new colors it permits to modify the luminance values without affecting the hue. The luminance component ('Y) is enhanced separately using the proposed method, next it is used for enhancing the chromatic components (u', v') by means of the center of gravity law of color mixing.

Investigation of self-adaptive LED surgical lighting based on entropy contrast enhancing method

NASA Astrophysics Data System (ADS)

Liu, Peng; Wang, Huihui; Zhang, Yaqin; Shen, Junfei; Wu, Rengmao; Zheng, Zhenrong; Li, Haifeng; Liu, Xu

2014-05-01

Investigation was performed to explore the possibility of enhancing contrast by varying the spectral distribution (SPD) of the surgical lighting. The illumination scenes with different SPDs were generated by the combination of a self-adaptive white light optimization method and the LED ceiling system, the images of biological sample are taken by a CCD camera and then processed by an 'Entropy' based contrast evaluation model which is proposed specific for surgery occasion. Compared with the neutral white LED based and traditional algorithm based image enhancing methods, the illumination based enhancing method turns out a better performance in contrast enhancing and improves the average contrast value about 9% and 6%, respectively. This low cost method is simple, practicable, and thus may provide an alternative solution for the expensive visual facility medical instruments.

Diagnostic performance of different measurement methods for lung nodule enhancement at quantitative contrast-enhanced computed tomography

NASA Astrophysics Data System (ADS)

Wormanns, Dag; Klotz, Ernst; Dregger, Uwe; Beyer, Florian; Heindel, Walter

2004-05-01

Lack of angiogenesis virtually excludes malignancy of a pulmonary nodule; assessment with quantitative contrast-enhanced CT (QECT) requires a reliable enhancement measurement technique. Diagnostic performance of different measurement methods in the distinction between malignant and benign nodules was evaluated. QECT (unenhanced scan and 4 post-contrast scans) was performed in 48 pulmonary nodules (12 malignant, 12 benign, 24 indeterminate). Nodule enhancement was the difference between the highest nodule density at any post-contrast scan and the unenhanced scan. Enhancement was determined with: A) the standard 2D method; B) a 3D method consisting of segmentation, removal of peripheral structures and density averaging. Enhancement curves were evaluated for their plausibility using a predefined set of criteria. Sensitivity and specificity were 100% and 33% for the 2D method resp. 92% and 55% for the 3D method using a threshold of 20 HU. One malignant nodule did not show significant enhancement with method B due to adjacent atelectasis which disappeared within the few minutes of the QECT examination. Better discrimination between benign and malignant lesions was achieved with a slightly higher threshold than proposed in the literature. Application of plausibility criteria to the enhancement curves rendered less plausibility faults with the 3D method. A new 3D method for analysis of QECT scans yielded less artefacts and better specificity in the discrimination between benign and malignant pulmonary nodules when using an appropriate enhancement threshold. Nevertheless, QECT results must be interpreted with care.

Quantitative contrast-enhanced ultrasound for monitoring vedolizumab therapy in inflammatory bowel disease patients: a pilot study.

PubMed

Goertz, Ruediger S; Klett, Daniel; Wildner, Dane; Atreya, Raja; Neurath, Markus F; Strobel, Deike

2018-01-01

Background Microvascularization of the bowel wall can be visualized and quantified non-invasively by software-assisted analysis of derived time-intensity curves. Purpose To perform software-based quantification of bowel wall perfusion using quantitative contrast-enhanced ultrasound (CEUS) according to clinical response in patients with inflammatory bowel disease treated with vedolizumab. Material and Methods In a prospective study, in 18 out of 34 patients, high-frequency ultrasound of bowel wall thickness using color Doppler flow combined with CEUS was performed at baseline and after 14 weeks of treatment with vedolizumab. Clinical activity scores at week 14 were used to differentiate between responders and non-responders. CEUS parameters were calculated by software analysis of the video loops. Results Nine of 18 patients (11 with Crohn's disease and seven with ulcerative colitis) showed response to treatment with vedolizumab. Overall, the responder group showed a significant decrease in the semi-quantitative color Doppler vascularization score. Amplitude-derived CEUS parameters of mural microvascularization such as peak enhancement or wash-in rate decreased in responders, in contrast with non-responders. Time-derived parameters remained stable or increased during treatment in all patients. Conclusion Analysis of bowel microvascularization by CEUS shows statistically significant changes in the wash-in-rate related to response of vedolizumab therapy.

Quantifying bone thickness, light transmission, and contrast interrelationships in transcranial photoacoustic imaging

NASA Astrophysics Data System (ADS)

Lediju Bell, Muyinatu A.; Ostrowski, Anastasia K.; Li, Ke; Kaanzides, Peter; Boctor, Emad

2015-03-01

We previously introduced photoacoustic imaging to detect blood vessels surrounded by bone and thereby eliminate the deadly risk of carotid artery injury during endonasal, transsphenoidal surgeries. Light would be transmitted through an optical fiber attached to the surgical drill, while a transcranial probe placed on the temporal region of the skull receives photoacoustic signals. This work quantifies changes in photoacoustic image contrast as the sphenoid bone is drilled. Frontal bone from a human adult cadaver skull was cut into seven 3 cm x 3 cm chips and sanded to thicknesses ranging 1-4 mm. For 700-940 nm wavelengths, the average optical transmission through these specimens increased from 19% to 44% as bone thickness decreased, with measurements agreeing with Monte Carlo simulations within 5%. These skull specimens were individually placed in the optical pathway of a 3.5 mm diameter, cylindrical, vessel-mimicking photoacoustic target, as the laser wavelength was varied between 700-940 nm. The mean optical insertion loss and photoacoustic image contrast loss due to the bone specimens were 56-80% and 46-79%, respectively, with the majority of change observed when the bone was <=2 mm thick. The decrease in contrast is directly proportional to insertion loss over this thickness range by factors of 0.8-1.1 when multiple wavelengths are considered. Results suggest that this proportional relationship may be used to determine the amount of bone that remains to be drilled when the thickness is 2 mm or less.

Quantifying Power Grid Risk from Geomagnetic Storms

NASA Astrophysics Data System (ADS)

Homeier, N.; Wei, L. H.; Gannon, J. L.

2012-12-01

We are creating a statistical model of the geophysical environment that can be used to quantify the geomagnetic storm hazard to power grid infrastructure. Our model is developed using a database of surface electric fields for the continental United States during a set of historical geomagnetic storms. These electric fields are derived from the SUPERMAG compilation of worldwide magnetometer data and surface impedances from the United States Geological Survey. This electric field data can be combined with a power grid model to determine GICs per node and reactive MVARs at each minute during a storm. Using publicly available substation locations, we derive relative risk maps by location by combining magnetic latitude and ground conductivity. We also estimate the surface electric fields during the August 1972 geomagnetic storm that caused a telephone cable outage across the middle of the United States. This event produced the largest surface electric fields in the continental U.S. in at least the past 40 years.

Image contrast enhancement with brightness preservation using an optimal gamma correction and weighted sum approach

NASA Astrophysics Data System (ADS)

Jiang, G.; Wong, C. Y.; Lin, S. C. F.; Rahman, M. A.; Ren, T. R.; Kwok, Ngaiming; Shi, Haiyan; Yu, Ying-Hao; Wu, Tonghai

2015-04-01

The enhancement of image contrast and preservation of image brightness are two important but conflicting objectives in image restoration. Previous attempts based on linear histogram equalization had achieved contrast enhancement, but exact preservation of brightness was not accomplished. A new perspective is taken here to provide balanced performance of contrast enhancement and brightness preservation simultaneously by casting the quest of such solution to an optimization problem. Specifically, the non-linear gamma correction method is adopted to enhance the contrast, while a weighted sum approach is employed for brightness preservation. In addition, the efficient golden search algorithm is exploited to determine the required optimal parameters to produce the enhanced images. Experiments are conducted on natural colour images captured under various indoor, outdoor and illumination conditions. Results have shown that the proposed method outperforms currently available methods in contrast to enhancement and brightness preservation.

Intravascular enhancement with identical iodine delivery rate using different iodine contrast media in a circulation phantom.

PubMed

Mihl, Casper; Wildberger, Joachim E; Jurencak, Tomas; Yanniello, Michael J; Nijssen, Estelle C; Kalafut, John F; Nalbantov, Georgi; Mühlenbruch, Georg; Behrendt, Florian F; Das, Marco

2013-11-01

Both iodine delivery rate (IDR) and iodine concentration are decisive factors for vascular enhancement in computed tomographic angiography. It is unclear, however, whether the use of high-iodine concentration contrast media is beneficial to lower iodine concentrations when IDR is kept identical. This study evaluates the effect of using different iodine concentrations on intravascular attenuation in a circulation phantom while maintaining a constant IDR. A circulation phantom with a low-pressure venous compartment and a high-pressure arterial compartment simulating physiological circulation parameters was used (heart rate, 60 beats per minute; stroke volume, 60 mL; blood pressure, 120/80 mm Hg). Maintaining a constant IDR (2.0 g/s) and a constant total iodine load (20 g), prewarmed (37°C) contrast media with differing iodine concentrations (240-400 mg/mL) were injected into the phantom using a double-headed power injector. Serial computed tomographic scans at the level of the ascending aorta (AA), the descending aorta (DA), and the left main coronary artery (LM) were obtained. Total amount of contrast volume (milliliters), iodine delivery (grams of iodine), peak flow rate (milliliter per second), and intravascular pressure (pounds per square inch) were monitored using a dedicated data acquisition program. Attenuation values in the AA, the DA, and the LM were constantly measured (Hounsfield unit [HU]). In addition, time-enhancement curves, aortic peak enhancement, and time to peak were determined. All contrast injection protocols resulted in similar attenuation values: the AA (516 [11] to 531 [37] HU), the DA (514 [17] to 531 [32] HU), and the LM (490 [10] to 507 [17] HU). No significant differences were found between the AA, the DA, and the LM for either peak enhancement (all P > 0.05) or mean time to peak (AA, 19.4 [0.58] to 20.1 [1.05] seconds; DA, 21.1 [1.0] to 21.4 [1.15] seconds; LM, 19.8 [0.58] to 20.1 [1.05] seconds). This phantom study demonstrates that

Abdominal Imaging with Contrast-enhanced Photon-counting CT: First Human Experience

PubMed Central

Pourmorteza, Amir; Symons, Rolf; Sandfort, Veit; Mallek, Marissa; Fuld, Matthew K.; Henderson, Gregory; Jones, Elizabeth C.; Malayeri, Ashkan A.; Folio, Les R.

2016-01-01

Purpose To evaluate the performance of a prototype photon-counting detector (PCD) computed tomography (CT) system for abdominal CT in humans and to compare the results with a conventional energy-integrating detector (EID). Materials and Methods The study was HIPAA-compliant and institutional review board–approved with informed consent. Fifteen asymptomatic volunteers (seven men; mean age, 58.2 years ± 9.8 [standard deviation]) were prospectively enrolled between September 2 and November 13, 2015. Radiation dose–matched delayed contrast agent–enhanced spiral and axial abdominal EID and PCD scans were acquired. Spiral images were scored for image quality (Wilcoxon signed-rank test) in five regions of interest by three radiologists blinded to the detector system, and the axial scans were used to assess Hounsfield unit accuracy in seven regions of interest (paired t test). Intraclass correlation coefficient (ICC) was used to assess reproducibility. PCD images were also used to calculate iodine concentration maps. Spatial resolution, noise-power spectrum, and Hounsfield unit accuracy of the systems were estimated by using a CT phantom. Results In both systems, scores were similar for image quality (median score, 4; P = .19), noise (median score, 3; P = .30), and artifact (median score, 1; P = .17), with good interrater agreement (image quality, noise, and artifact ICC: 0.84, 0.88, and 0.74, respectively). Hounsfield unit values, spatial resolution, and noise-power spectrum were also similar with the exception of mean Hounsfield unit value in the spinal canal, which was lower in the PCD than the EID images because of beam hardening (20 HU vs 36.5 HU; P < .001). Contrast-to-noise ratio of enhanced kidney tissue was improved with PCD iodine mapping compared with EID (5.2 ± 1.3 vs 4.0 ± 1.3; P < .001). Conclusion The performance of PCD showed no statistically significant difference compared with EID when the abdomen was evaluated in a conventional scan mode. PCD

Real-time 3-dimensional contrast-enhanced ultrasound in detecting hemorrhage of blunt renal trauma.

PubMed

Xu, Rui-Xue; Li, Ye-Kuo; Li, Ting; Wang, Sha-Sha; Yuan, Gui-Zhong; Zhou, Qun-Fang; Zheng, Hai-Rong; Yan, Fei

2013-10-01

The objective of this study is to evaluate the diagnostic value of real-time 3-dimensional contrast-enhanced ultrasound in the hemorrhage of blunt renal trauma. Eighteen healthy New Zealand white rabbits were randomly divided into 3 groups. Blunt renal trauma was performed on each group by using minitype striker. Ultrasonography, color Doppler flow imaging, and contrast-enhanced 2-dimensional and real-time 3-dimensional ultrasound were applied before and after the strike. The time to shock and blood pressure were subjected to statistical analysis. Then, a comparative study of ultrasound and pathology was carried out. All the struck kidneys were traumatic. In the ultrasonography, free fluid was found under the renal capsule. In the color Doppler flow imaging, active hemorrhage was not identified. In 2-dimensional contrast-enhanced ultrasound, active hemorrhage of the damaged kidney was characterized. Real-time 3-dimensional contrast-enhanced ultrasound showed a real-time and stereoscopic ongoing bleeding of the injured kidney. The wider the hemorrhage area in 4-dimensional contrast-enhanced ultrasound was, the faster the blood pressure decreased. Real-time 3-dimensional contrast-enhanced ultrasound is a promising noninvasive tool for stereoscopically and vividly detecting ongoing hemorrhage of blunt renal trauma in real time. © 2013.

Deep learning enables reduced gadolinium dose for contrast-enhanced brain MRI.

PubMed

Gong, Enhao; Pauly, John M; Wintermark, Max; Zaharchuk, Greg

2018-02-13

There are concerns over gadolinium deposition from gadolinium-based contrast agents (GBCA) administration. To reduce gadolinium dose in contrast-enhanced brain MRI using a deep learning method. Retrospective, crossover. Sixty patients receiving clinically indicated contrast-enhanced brain MRI. 3D T 1 -weighted inversion-recovery prepped fast-spoiled-gradient-echo (IR-FSPGR) imaging was acquired at both 1.5T and 3T. In 60 brain MRI exams, the IR-FSPGR sequence was obtained under three conditions: precontrast, postcontrast images with 10% low-dose (0.01mmol/kg) and 100% full-dose (0.1 mmol/kg) of gadobenate dimeglumine. We trained a deep learning model using the first 10 cases (with mixed indications) to approximate full-dose images from the precontrast and low-dose images. Synthesized full-dose images were created using the trained model in two test sets: 20 patients with mixed indications and 30 patients with glioma. For both test sets, low-dose, true full-dose, and the synthesized full-dose postcontrast image sets were compared quantitatively using peak-signal-to-noise-ratios (PSNR) and structural-similarity-index (SSIM). For the test set comprised of 20 patients with mixed indications, two neuroradiologists scored blindly and independently for the three postcontrast image sets, evaluating image quality, motion-artifact suppression, and contrast enhancement compared with precontrast images. Results were assessed using paired t-tests and noninferiority tests. The proposed deep learning method yielded significant (n = 50, P < 0.001) improvements over the low-dose images (>5 dB PSNR gains and >11.0% SSIM). Ratings on image quality (n = 20, P = 0.003) and contrast enhancement (n = 20, P < 0.001) were significantly increased. Compared to true full-dose images, the synthesized full-dose images have a slight but not significant reduction in image quality (n = 20, P = 0.083) and contrast enhancement (n = 20, P = 0.068). Slightly

Intratumor distribution and test-retest comparisons of physiological parameters quantified by dynamic contrast-enhanced MRI in rat U251 glioma.

PubMed

Aryal, Madhava P; Nagaraja, Tavarekere N; Brown, Stephen L; Lu, Mei; Bagher-Ebadian, Hassan; Ding, Guangliang; Panda, Swayamprava; Keenan, Kelly; Cabral, Glauber; Mikkelsen, Tom; Ewing, James R

2014-10-01

The distribution of dynamic contrast-enhanced MRI (DCE-MRI) parametric estimates in a rat U251 glioma model was analyzed. Using Magnevist as contrast agent (CA), 17 nude rats implanted with U251 cerebral glioma were studied by DCE-MRI twice in a 24 h interval. A data-driven analysis selected one of three models to estimate either (1) plasma volume (vp), (2) vp and forward volume transfer constant (K(trans)) or (3) vp, K(trans) and interstitial volume fraction (ve), constituting Models 1, 2 and 3, respectively. CA distribution volume (VD) was estimated in Model 3 regions by Logan plots. Regions of interest (ROIs) were selected by model. In the Model 3 ROI, descriptors of parameter distributions--mean, median, variance and skewness--were calculated and compared between the two time points for repeatability. All distributions of parametric estimates in Model 3 ROIs were positively skewed. Test-retest differences between population summaries for any parameter were not significant (p ≥ 0.10; Wilcoxon signed-rank and paired t tests). These and similar measures of parametric distribution and test-retest variance from other tumor models can be used to inform the choice of biomarkers that best summarize tumor status and treatment effects. Copyright © 2014 John Wiley & Sons, Ltd.

Assessment of contrast enhanced respiration managed cone-beam CT for image guided radiotherapy of intrahepatic tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, Nikolaj K. G., E-mail: nkyj@regionsjaelland.dk; Stewart, Errol; Imaging Research Lab, Robarts Research Institute, London, Ontario N6A 5B7

2014-05-15

Purpose: Contrast enhancement and respiration management are widely used during image acquisition for radiotherapy treatment planning of liver tumors along with respiration management at the treatment unit. However, neither respiration management nor intravenous contrast is commonly used during cone-beam CT (CBCT) image acquisition for alignment prior to radiotherapy. In this study, the authors investigate the potential gains of injecting an iodinated contrast agent in combination with respiration management during CBCT acquisition for liver tumor radiotherapy. Methods: Five rabbits with implanted liver tumors were subjected to CBCT with and without motion management and contrast injection. The acquired CBCT images were registeredmore » to the planning CT to determine alignment accuracy and dosimetric impact. The authors developed a simulation tool for simulating contrast-enhanced CBCT images from dynamic contrast enhanced CT imaging (DCE-CT) to determine optimal contrast injection protocols. The tool was validated against contrast-enhanced CBCT of the rabbit subjects and was used for five human patients diagnosed with hepatocellular carcinoma. Results: In the rabbit experiment, when neither motion management nor contrast was used, tumor centroid misalignment between planning image and CBCT was 9.2 mm. This was reduced to 2.8 mm when both techniques were employed. Tumors were not visualized in clinical CBCT images of human subjects. Simulated contrast-enhanced CBCT was found to improve tumor contrast in all subjects. Different patients were found to require different contrast injections to maximize tumor contrast. Conclusions: Based on the authors’ animal study, respiration managed contrast enhanced CBCT improves IGRT significantly. Contrast enhanced CBCT benefits from patient specific tracer kinetics determined from DCE-CT.« less

Neutral vs positive oral contrast in diagnosing acute appendicitis with contrast-enhanced CT: sensitivity, specificity, reader confidence and interpretation time

PubMed Central

Naeger, D M; Chang, S D; Kolli, P; Shah, V; Huang, W; Thoeni, R F

2011-01-01

Objective The study compared the sensitivity, specificity, confidence and interpretation time of readers of differing experience in diagnosing acute appendicitis with contrast-enhanced CT using neutral vs positive oral contrast agents. Methods Contrast-enhanced CT for right lower quadrant or right flank pain was performed in 200 patients with neutral and 200 with positive oral contrast including 199 with proven acute appendicitis and 201 with other diagnoses. Test set disease prevalence was 50%. Two experienced gastrointestinal radiologists, one fellow and two first-year residents blindly assessed all studies for appendicitis (2000 readings) and assigned confidence scores (1=poor to 4=excellent). Receiver operating characteristic (ROC) curves were generated. Total interpretation time was recorded. Each reader's interpretation with the two agents was compared using standard statistical methods. Results Average reader sensitivity was found to be 96% (range 91–99%) with positive and 95% (89–98%) with neutral oral contrast; specificity was 96% (92–98%) and 94% (90–97%). For each reader, no statistically significant difference was found between the two agents (sensitivities p-values >0.6; specificities p-values>0.08), in the area under the ROC curve (range 0.95–0.99) or in average interpretation times. In cases without appendicitis, positive oral contrast demonstrated improved appendix identification (average 90% vs 78%) and higher confidence scores for three readers. Average interpretation times showed no statistically significant differences between the agents. Conclusion Neutral vs positive oral contrast does not affect the accuracy of contrast-enhanced CT for diagnosing acute appendicitis. Although positive oral contrast might help to identify normal appendices, we continue to use neutral oral contrast given its other potential benefits. PMID:20959365

Temporal contrast enhancement of a femtosecond fiber CPA system by filtering of SPM broadened spectra

NASA Astrophysics Data System (ADS)

Buldt, J.; Müller, M.; Klas, R.; Eidam, T.; Limpert, J.; Tünnermann, A.

2018-02-01

We present a novel approach for temporal contrast enhancement of energetic laser pulses by filtered SPM broadened spectra. A measured temporal contrast enhancement by at least 7 orders of magnitude in a simple setup has been achieved. This technique is applicable to a wide range of laser parameters and poses a highly efficient alternative to existing contrast-enhancement methods.

Contrast-enhanced voiding urosonography: in vitro evaluation of a second-generation ultrasound contrast agent for in vivo optimization.

PubMed

Back, Susan J; Edgar, J Christopher; Canning, Douglas A; Darge, Kassa

2015-09-01

Pediatric contrast-enhanced ultrasound (CEUS) is primarily performed outside the United States where a track record for safety in intravenous and intravesical applications has been established. Contrast-enhanced voiding urosonography (ceVUS) has also been shown to have a much higher rate of vesicoureteral reflux detection compared to voiding cystourethrography. US contrast agents available in the United States differ from those abroad. Optison® (GE Healthcare, Princeton, NJ) is such an US contrast agent. While Optison® has similar characteristics to other second-generation agents, it has never been used for ceVUS. In vitro optimization of dose and imaging parameters as well as assessment of contrast visualization when delivered in conditions similar to ceVUS are necessary starting points prior to in vivo applications. To optimize the intravesical use of Optison® in vitro for ceVUS before its use in pediatric studies. The experimental design simulated intravesical use. Using 9- and 12-MHz linear transducers, we scanned 20-mL syringes varying mechanical index, US contrast agent concentration (0.25%, 0.5%, 1.0%), solvent (saline, urine, radiographic contrast agent) and time out of refrigeration. We evaluated mechanical index settings and contrast duration, optimized the contrast dose, measured the effect of urine and radiographic contrast agent, and the impact of length of time of contrast outside of the refrigerator on US contrast appearance. We scanned 50-ml saline bags to assess the appearance and duration of US contrast with different delivery systems (injection vs. infusion). Consistent contrast visualization was achieved at a mechanical index of 0.06-0.17 and 0.11-0.48 for the L9 and L12 MHz transducers (P < 0.01), respectively. Thus, it was necessary to increase the mechanical index for better contrast visualization of the microbubbles with a higher transducer frequency. The lowest mechanical index for earliest visible microbubble destruction was 0

Counter-propagating wave interaction for contrast-enhanced ultrasound imaging

NASA Astrophysics Data System (ADS)

Renaud, G.; Bosch, J. G.; ten Kate, G. L.; Shamdasani, V.; Entrekin, R.; de Jong, N.; van der Steen, A. F. W.

2012-11-01

Most techniques for contrast-enhanced ultrasound imaging require linear propagation to detect nonlinear scattering of contrast agent microbubbles. Waveform distortion due to nonlinear propagation impairs their ability to distinguish microbubbles from tissue. As a result, tissue can be misclassified as microbubbles, and contrast agent concentration can be overestimated; therefore, these artifacts can significantly impair the quality of medical diagnoses. Contrary to biological tissue, lipid-coated gas microbubbles used as a contrast agent allow the interaction of two acoustic waves propagating in opposite directions (counter-propagation). Based on that principle, we describe a strategy to detect microbubbles that is free from nonlinear propagation artifacts. In vitro images were acquired with an ultrasound scanner in a phantom of tissue-mimicking material with a cavity containing a contrast agent. Unlike the default mode of the scanner using amplitude modulation to detect microbubbles, the pulse sequence exploiting counter-propagating wave interaction creates no pseudoenhancement behind the cavity in the contrast image.

Contrast-enhanced digital mammography (CEDM): imaging modeling, computer simulations, and phantom study

NASA Astrophysics Data System (ADS)

Chen, Biao; Jing, Zhenxue; Smith, Andrew

2005-04-01

Contrast enhanced digital mammography (CEDM), which is based upon the analysis of a series of x-ray projection images acquired before/after the administration of contrast agents, may provide physicians critical physiologic and morphologic information of breast lesions to determine the malignancy of lesions. This paper proposes to combine the kinetic analysis (KA) of contrast agent uptake/washout process and the dual-energy (DE) contrast enhancement together to formulate a hybrid contrast enhanced breast-imaging framework. The quantitative characteristics of materials and imaging components in the x-ray imaging chain, including x-ray tube (tungsten) spectrum, filter, breast tissues/lesions, contrast agents (non-ionized iodine solution), and selenium detector, were systematically modeled. The contrast-noise-ration (CNR) of iodinated lesions and mean absorbed glandular dose were estimated mathematically. The x-ray techniques optimization was conducted through a series of computer simulations to find the optimal tube voltage, filter thickness, and exposure levels for various breast thicknesses, breast density, and detectable contrast agent concentration levels in terms of detection efficiency (CNR2/dose). A phantom study was performed on a modified Selenia full field digital mammography system to verify the simulated results. The dose level was comparable to the dose in diagnostic mode (less than 4 mGy for an average 4.2 cm compressed breast). The results from the computer simulations and phantom study are being used to optimize an ongoing clinical study.

Evaluation of Eu(II) -based positive contrast enhancement after intravenous, intraperitoneal, and subcutaneous injections.

PubMed

Ekanger, Levi A; Polin, Lisa A; Shen, Yimin; Haacke, E Mark; Allen, Matthew J

2016-07-01

Eu(II) -based contrast agents offer physiologically relevant, metal-based redox sensing that is unachievable with Gd(III) -based contrast agents. To evaluate the in vivo contrast enhancement of Eu(II) as a function of injection type, we performed intravenous, intraperitoneal, and subcutaneous injections in mice. Our data reveal a correlation between reported oxygen content and expected rates of diffusion with the persistence of Eu(II) -based contrast enhancement. Biodistribution studies revealed europium clearance through the liver and kidneys for intravenous and intraperitoneal injections, but no contrast enhancement was observed in organs associated with clearance. These data represent a step toward understanding the behavior of Eu(II) -based complexes in vivo. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Segmentation methods for breast vasculature in dual-energy contrast-enhanced digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Lau, Kristen C.; Lee, Hyo Min; Singh, Tanushriya; Maidment, Andrew D. A.

2015-03-01

Dual-energy contrast-enhanced digital breast tomosynthesis (DE CE-DBT) uses an iodinated contrast agent to image the three-dimensional breast vasculature. The University of Pennsylvania has an ongoing DE CE-DBT clinical study in patients with known breast cancers. The breast is compressed continuously and imaged at four time points (1 pre-contrast; 3 post-contrast). DE images are obtained by a weighted logarithmic subtraction of the high-energy (HE) and low-energy (LE) image pairs. Temporal subtraction of the post-contrast DE images from the pre-contrast DE image is performed to analyze iodine uptake. Our previous work investigated image registration methods to correct for patient motion, enhancing the evaluation of vascular kinetics. In this project we investigate a segmentation algorithm which identifies blood vessels in the breast from our temporal DE subtraction images. Anisotropic diffusion filtering, Gabor filtering, and morphological filtering are used for the enhancement of vessel features. Vessel labeling methods are then used to distinguish vessel and background features successfully. Statistical and clinical evaluations of segmentation accuracy in DE-CBT images are ongoing.

Tolerance of image enhancement brightness and contrast in lateral cephalometric digital radiography for Steiner analysis

NASA Astrophysics Data System (ADS)

Rianti, R. A.; Priaminiarti, M.; Syahraini, S. I.

2017-08-01

Image enhancement brightness and contrast can be adjusted on lateral cephalometric digital radiographs to improve image quality and anatomic landmarks for measurement by Steiner analysis. To determine the limit value for adjustments of image enhancement brightness and contrast in lateral cephalometric digital radiography for Steiner analysis. Image enhancement brightness and contrast were adjusted on 100 lateral cephalometric radiography in 10-point increments (-30, -20, -10, 0, +10, +20, +30). Steiner analysis measurements were then performed by two observers. Reliabilities were tested by the Interclass Correlation Coefficient (ICC) and significance tested by ANOVA or the Kruskal Wallis test. No significant differences were detected in lateral cephalometric analysis measurements following adjustment of the image enhancement brightness and contrast. The limit value of adjustments of the image enhancement brightness and contrast associated with incremental 10-point changes (-30, -20, -10, 0, +10, +20, +30) does not affect the results of Steiner analysis.

Contrast-enhanced ultrasound imaging of active bleeding associated with hepatic and splenic trauma.

PubMed

Lv, F; Tang, J; Luo, Y; Li, Z; Meng, X; Zhu, Z; Li, T

2011-10-01

The aim of this study was to evaluate contrast-enhanced ultrasound (CEUS) imaging of active bleeding from hepatic and splenic trauma. Three hundred and ninety-two patients with liver or/and spleen trauma (179 liver and 217 spleen injuries), who underwent CEUS examinations following contrast-enhanced computed tomography (CT), were enrolled in this retrospective study over a period of >4 years. CEUS detected contrast medium extravasation or pooling in 16% (63/396) of liver or spleen lesions in 61 patients, which was confirmed by contrast-enhanced CT. Special attention was paid to observing the presence, location, and characteristics of the extravasated or pooled contrast medium. The CEUS detection rate for active bleeding was not different from that of contrast-enhanced CT (p=0.333). Information from surgery, minimally invasive treatment and conservative treatment was used as reference standard, and the sensitivities of the two techniques were not different (p=0.122). Of 63 lesions in 61 patients, CEUS showed that 74.6% (47/63) (21 liver lesions and 26 spleen lesions) presented contrast medium extravasation or pooling, both in the organ and out the capsule, in 14.3% (9/63) and only outside the capsule in 11.1% (7/63). CEUS imaging of active bleeding from hepatic and splenic trauma presented various characteristics, and the sizes and shapes of the active bleeding due to contrast medium extravasation or pooling were variable. CEUS can show the active bleeding associated with hepatic and splenic trauma with various imaging characteristics, thus making it possible to diagnose active bleeding using CEUS.

A multiresolution processing method for contrast enhancement in portal imaging.

PubMed

Gonzalez-Lopez, Antonio

2018-06-18

Portal images have a unique feature among the imaging modalities used in radiotherapy: they provide direct visualization of the irradiated volumes. However, contrast and spatial resolution are strongly limited due to the high energy of the radiation sources. Because of this, imaging modalities using x-ray energy beams have gained importance in the verification of patient positioning, replacing portal imaging. The purpose of this work was to develop a method for the enhancement of local contrast in portal images. The method operates in the subbands of a wavelet decomposition of the image, re-scaling them in such a way that coefficients in the high and medium resolution subbands are amplified, an approach totally different of those operating on the image histogram, widely used nowadays. Portal images of an anthropomorphic phantom were acquired in an electronic portal imaging device (EPID). Then, different re-scaling strategies were investigated, studying the effects of the scaling parameters on the enhanced images. Also, the effect of using different types of transforms was studied. Finally, the implemented methods were combined with histogram equalization methods like the contrast limited adaptive histogram equalization (CLAHE), and these combinations were compared. Uniform amplification of the detail subbands shows the best results in contrast enhancement. On the other hand, linear re-escalation of the high resolution subbands increases the visibility of fine detail of the images, at the expense of an increase in noise levels. Also, since processing is applied only to detail subbands, not to the approximation, the mean gray level of the image is minimally modified and no further display adjustments are required. It is shown that re-escalation of the detail subbands of portal images can be used as an efficient method for the enhancement of both, the local contrast and the resolution of these images. © 2018 Institute of

Non-contrast-enhanced MR portography and hepatic venography with time-spatial labeling inversion pulses: comparison at 1.5 Tesla and 3 Tesla

PubMed Central

Isoda, Hiroyoshi; Furuta, Akihiro; Togashi, Kaori

2015-01-01

Background A 3 Tesla (3 T) magnetic resonance (MR) scanner is a promising tool for upper abdominal MR angiography. However, there is no report focused on the image quality of non-contrast-enhanced MR portography and hepatic venography at 3 T. Purpose To compare and evaluate images of non-contrast-enhanced MR portography and hepatic venography with time-spatial labeling inversion pulses (Time-SLIP) at 1.5 Tesla (1.5 T) and 3 T. Material and Methods Twenty-five healthy volunteers were examined using respiratory-triggered three-dimensional balanced steady-state free-precession (bSSFP) with Time-SLIP. For portography, we used one tagging pulse (selective inversion recovery) and one non-selective inversion recovery pulse; for venography, two tagging pulses were used. The relative signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were quantified, and the quality of visualization was evaluated. Results The CNRs of the main portal vein, right portal vein, and left portal vein at 3 T were better than at 1.5 T. The image quality scores for the portal branches of segment 4, 5, and 8 were significantly higher at 3 T than at 1.5 T. The CNR of the right hepatic vein (RHV) at 3 T was significantly lower than at 1.5 T. The image quality scores of RHV and the middle hepatic vein were higher at 1.5 T than at 3 T. For RHV visualization, the difference was statistically significant. Conclusion Non-contrast-enhanced MR portography with Time-SLIP at 3 T significantly improved visualization of the peripheral branch in healthy volunteers compared with1.5 T. Non-contrast-enhanced MR hepatic venography at 1.5 T was better than at 3 T. PMID:26019890

Power enhanced frequency conversion system

NASA Technical Reports Server (NTRS)

Sanders, Steven (Inventor); Lang, Robert J. (Inventor); Waarts, Robert G. (Inventor)

2001-01-01

A frequency conversion system includes at least one source providing a first near-IR wavelength output including a gain medium for providing high power amplification, such as double clad fiber amplifier, a double clad fiber laser or a semiconductor tapered amplifier to enhance the power output level of the near-IR wavelength output. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Ra-man/Brillouin amplifier or oscillator between the high power source and the NFM device.

Contrast-enhanced 3D micro-CT of plant tissues using different impregnation techniques.

PubMed

Wang, Zi; Verboven, Pieter; Nicolai, Bart

2017-01-01

X-ray micro-CT has increasingly been used for 3D imaging of plant structures. At the micrometer resolution however, limitations in X-ray contrast often lead to datasets with poor qualitative and quantitative measures, especially within dense cell clusters of plant tissue specimens. The current study developed protocols for delivering a cesium based contrast enhancing solution to varying plant tissue specimens for the purpose of improving 3D tissue structure characterization within plant specimens, accompanied by new image processing workflows to extract the additional data generated by the contrast enhanced scans. Following passive delivery of a 10% cesium iodide contrast solution, significant increases of 85.4 and 38.0% in analyzable cell volumes were observed in pear fruit hypanthium and tomato fruit outer mesocarp samples. A significant increase of 139.6% in the number of analyzable cells was observed in the pear fruit samples along the added ability to locate and isolate better brachysclereids and vasculature in the sample volume. Furthermore, contrast enhancement resulted in significant improvement in the definition of collenchyma and parenchyma in the petiolule of tomato leaflets, from which both qualitative and quantitative data can be extracted with respect to cell measures. However, contrast enhancement was not achieved in leaf vasculature and mesophyll tissue due to fundamental limitations. Active contrast delivery to apple fruit hypanthium samples did yield a small but insignificant increase in analyzable volume and cells, but data on vasculature can now be extracted better in correspondence to the pear hypanthium samples. Contrast delivery thus improved visualization and analysis the most in dense tissue types. The cesium based contrast enhancing protocols and workflows can be utilized to obtain detailed 3D data on the internal microstructure of plant samples, and can be adapted to additional samples of interest with minimal effort. The resulting

Prognostic significance of contrast-enhanced CT attenuation value in extrahepatic cholangiocarcinoma.

PubMed

Asayama, Yoshiki; Nishie, Akihiro; Ishigami, Kousei; Ushijima, Yasuhiro; Takayama, Yukihisa; Okamoto, Daisuke; Fujita, Nobuhiro; Ohtsuka, Takao; Yoshizumi, Tomoharu; Aishima, Shinichi; Oda, Yoshinao; Honda, Hiroshi

2017-06-01

To determine whether washout characteristics of dynamic contrast-enhanced computed tomography (CT) could predict survival in patients with extrahepatic cholangiocarcinoma (EHC). This study collected 46 resected cases. All cases were examined by dynamic contrast study on multidetector-row CT. Region-of-interest measurements were obtained at the non-enhanced, portal venous phase and delayed phase in the tumour and were used to calculate the washout ratio as follows: [(attenuation value at portal venous phase CT - attenuation value at delayed enhanced CT)/(attenuation value at portal venous phase CT - attenuation value at unenhanced CT)] × 100. On the basis of the median washout ratio, we classified the cases into two groups, a high-washout group and low-washout group. Associations between overall survival and various factors including washout rates were analysed. The median washout ratio was 29.4 %. Univariate analysis revealed that a lower washout ratio, venous invasion, lymphatic permeation and lymph node metastasis were associated with shorter survival. Multivariate analysis identified the lower washout ratio as an independent prognostic factor (hazard ratio, 3.768; p value, 0.027). The washout ratio obtained from the contrast-enhanced CT may be a useful imaging biomarker for the prediction of survival of patients with EHC. • Dynamic contrast study can evaluate the aggressiveness of extrahepatic cholangiocarcinoma. • A lower washout ratio was an independent prognostic factor for overall survival. • CT can predict survival and inform decisions on surgical options or chemotherapy.

Towards Dynamic Contrast Specific Ultrasound Tomography

NASA Astrophysics Data System (ADS)

Demi, Libertario; van Sloun, Ruud J. G.; Wijkstra, Hessel; Mischi, Massimo

2016-10-01

We report on the first study demonstrating the ability of a recently-developed, contrast-enhanced, ultrasound imaging method, referred to as cumulative phase delay imaging (CPDI), to image and quantify ultrasound contrast agent (UCA) kinetics. Unlike standard ultrasound tomography, which exploits changes in speed of sound and attenuation, CPDI is based on a marker specific to UCAs, thus enabling dynamic contrast-specific ultrasound tomography (DCS-UST). For breast imaging, DCS-UST will lead to a more practical, faster, and less operator-dependent imaging procedure compared to standard echo-contrast, while preserving accurate imaging of contrast kinetics. Moreover, a linear relation between CPD values and ultrasound second-harmonic intensity was measured (coefficient of determination = 0.87). DCS-UST can find clinical applications as a diagnostic method for breast cancer localization, adding important features to multi-parametric ultrasound tomography of the breast.

Towards Dynamic Contrast Specific Ultrasound Tomography.

PubMed

Demi, Libertario; Van Sloun, Ruud J G; Wijkstra, Hessel; Mischi, Massimo

2016-10-05

We report on the first study demonstrating the ability of a recently-developed, contrast-enhanced, ultrasound imaging method, referred to as cumulative phase delay imaging (CPDI), to image and quantify ultrasound contrast agent (UCA) kinetics. Unlike standard ultrasound tomography, which exploits changes in speed of sound and attenuation, CPDI is based on a marker specific to UCAs, thus enabling dynamic contrast-specific ultrasound tomography (DCS-UST). For breast imaging, DCS-UST will lead to a more practical, faster, and less operator-dependent imaging procedure compared to standard echo-contrast, while preserving accurate imaging of contrast kinetics. Moreover, a linear relation between CPD values and ultrasound second-harmonic intensity was measured (coefficient of determination = 0.87). DCS-UST can find clinical applications as a diagnostic method for breast cancer localization, adding important features to multi-parametric ultrasound tomography of the breast.

Towards Dynamic Contrast Specific Ultrasound Tomography

PubMed Central

Demi, Libertario; Van Sloun, Ruud J. G.; Wijkstra, Hessel; Mischi, Massimo

2016-01-01

We report on the first study demonstrating the ability of a recently-developed, contrast-enhanced, ultrasound imaging method, referred to as cumulative phase delay imaging (CPDI), to image and quantify ultrasound contrast agent (UCA) kinetics. Unlike standard ultrasound tomography, which exploits changes in speed of sound and attenuation, CPDI is based on a marker specific to UCAs, thus enabling dynamic contrast-specific ultrasound tomography (DCS-UST). For breast imaging, DCS-UST will lead to a more practical, faster, and less operator-dependent imaging procedure compared to standard echo-contrast, while preserving accurate imaging of contrast kinetics. Moreover, a linear relation between CPD values and ultrasound second-harmonic intensity was measured (coefficient of determination = 0.87). DCS-UST can find clinical applications as a diagnostic method for breast cancer localization, adding important features to multi-parametric ultrasound tomography of the breast. PMID:27703251

Contrast-enhanced sonography for quantitative assessment of portal hypertension in patients with liver cirrhosis.

PubMed

Qu, En-Ze; Zhang, Ying-Cai; Li, Zhi-Yan; Liu, Yang; Wang, Jin-Rui

2014-11-01

The clinical utility of contrast-enhanced sonography in portal hypertension remains unclear. We explored the feasibility of using contrast-enhanced sonography for noninvasive assessment of portal venous pressure. Twenty healthy individuals (control group; 9 men; mean age, 46.4 years) and 18 patients with portal hypertension (15 men; mean age, 46.2 years) were enrolled in this study. The portal hypertension group included patients who underwent splenectomy and pericardial blood vessel disarticulation at our hospital from October 2010 to March 2011. One week before surgery, patients with portal hypertension underwent preoperative liver contrast-enhanced sonography. Two-dimensional, Doppler, and contrast-enhanced sonographic parameters were compared between the groups. Portal venous pressure was measured intraoperatively by portal vein puncture in the portal hypertension group, and its relationship with the other parameters was analyzed. The 2-dimensional, Doppler, and contrast-enhanced sonographic parameters differed between the groups (P < .01). Portal venous pressure was inversely correlated with the area under the portal vein/hepatic artery time-intensity curve ratio (Qp/Qa), portal vein/hepatic artery strength ratio (Ip/Ia), and portal vein/hepatic artery wash-in perfusion slope ratio (βp/βa), with correlation coefficients of -0.701, -0.625, and -0.494, respectively. Measurement of the liver contrast-enhanced sonographic parameters Qp/Qa, Ip/Ia, and βp/βa could be used as a new quantitative method for noninvasively assessing portal venous pressure. © 2014 by the American Institute of Ultrasound in Medicine.

In Vivo High-Frequency, Contrast-Enhanced Ultrasonography of Uveal Melanoma in Mice: Imaging Features and Histopathologic Correlations

PubMed Central

Zhang, Qing; Yang, Hua; Kang, Shin J.; Wang, Yanggan; Wang, Geoffrey D.; Coulthard, Tonya

2011-01-01

Purpose. To evaluate the usefulness of in vivo imaging of uveal melanoma in mice using high-frequency contrast-enhanced ultrasound (HF-CE-US) with 2D or 3D modes and to correlate the sonographic findings with histopathologic characteristics. Methods. Fourteen 12-week-old C57BL6 mice were inoculated into their right eyes with aliquots of 5 × 105/2.5 μL B16LS9 melanoma cells and were randomly assigned to either of two groups. At 7 days after inoculation, tumor-bearing eyes in group 1 (n = 8) were imaged using HF-CE-US to determine the 2D tumor size and relative blood volume; eyes in group 2 (n = 6) were imaged by 3D microbubble contrast-enhanced ultrasound, and the tumor volume was determined. Histologic tumor burden was quantified in enucleated eyes by image processing software, and microvascular density was determined by counting von Willebrand factor-positive vascular channels. Ultrasound images were evaluated and compared with histopathologic findings. Results. Using HF-CE-US, melanomas were visualized as relatively hyperechoic regions. The intraobserver variability of sonographic measurements was 9.65% ± 7.89%, and the coefficient of variation for multiple measurements was 7.33% ± 5.71%. The correlation coefficient of sonographic volume or size and histologic area was 0.71 (P = 0.11) and 0.79 (P = 0.32). The relative blood volume within the tumor demonstrated sonographically correlated significantly with histologic tumor vascularity (r = 0.83; P < 0.001). Conclusions. There was a positive linear correlation between sonographic tumor measurements and histologic tumor burden in the mouse ocular melanoma model. Contrast-enhanced intensity corresponded with microvascular density and blood volume. HF-CE-US is a real-time, noninvasive, reliable method for in vivo evaluation of experimental intraocular melanoma tumor area and relative blood volume. PMID:21245408

Contrast enhanced imaging with a stationary digital breast tomosynthesis system

NASA Astrophysics Data System (ADS)

Puett, Connor; Calliste, Jabari; Wu, Gongting; Inscoe, Christina R.; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

2017-03-01

Digital breast tomosynthesis (DBT) captures some depth information and thereby improves the conspicuity of breast lesions, compared to standard mammography. Using contrast during DBT may also help distinguish malignant from benign sites. However, adequate visualization of the low iodine signal requires a subtraction step to remove background signal and increase lesion contrast. Additionally, attention to factors that limit contrast, including scatter, noise, and artifact, are important during the image acquisition and post-acquisition processing steps. Stationary DBT (sDBT) is an emerging technology that offers a higher spatial and temporal resolution than conventional DBT. This phantom-based study explored contrast-enhanced sDBT (CE sDBT) across a range of clinically-appropriate iodine concentrations, lesion sizes, and breast thicknesses. The protocol included an effective scatter correction method and an iterative reconstruction technique that is unique to the sDBT system. The study demonstrated the ability of this CE sDBT system to collect projection images adequate for both temporal subtraction (TS) and dual-energy subtraction (DES). Additionally, the reconstruction approach preserved the improved contrast-to-noise ratio (CNR) achieved in the subtraction step. Finally, scatter correction increased the iodine signal and CNR of iodine-containing regions in projection views and reconstructed image slices during both TS and DES. These findings support the ongoing study of sDBT as a potentially useful tool for contrast-enhanced breast imaging and also highlight the significant effect that scatter has on image quality during DBT.

Enhanced-Contrast Viewing of White-Hot Objects in Furnaces

NASA Technical Reports Server (NTRS)

Witherow, William K.; Holmes, Richard R.; Kurtz, Robert L.

2006-01-01

An apparatus denoted a laser image contrast enhancement system (LICES) increases the contrast with which one can view a target glowing with blackbody radiation (a white-hot object) against a background of blackbody radiation in a furnace at a temperature as high as approximately 1,500 C. The apparatus utilizes a combination of narrowband illumination, along with band-pass filtering and polarization filtering to pass illumination reflected by the target while suppressing blackbody light from both the object and its background.

Contrast-enhanced ultrasound in the diagnosis of nodules in liver cirrhosis

PubMed Central

Kim, Tae Kyoung; Jang, Hyun-Jung

2014-01-01

Contrast-enhanced ultrasound (CEUS) using microbubble contrast agents are useful for the diagnosis of the nodules in liver cirrhosis. CEUS can be used as a problem-solving method for indeterminate nodules on computed tomography (CT) or magnetic resonance imaging (MRI) or as an initial diagnostic test for small newly detected liver nodules. CEUS has unique advantages over CT and MRI including no renal excretion of contrast, real-time imaging capability, and purely intravascular contrast. Hepatocellular carcinoma (HCC) is characterized by arterial-phase hypervascularity and later washout (negative enhancement). Benign nodules such as regenerative nodules or dysplastic nodules are usually isoechoic or slightly hypoechoic in the arterial phase and isoechoic in the late phase. However, there are occasional HCC lesions with atypical enhancement including hypovascular HCC and hypervascular HCC without washout. Cholangiocarcinomas are infrequently detected during HCC surveillance and mostly show rim-like or diffuse hypervascularity followed by rapid washout. Hemangiomas are often found at HCC surveillance and are easily diagnosed by CEUS. CEUS can be effectively used in the diagnostic work-up of small nodules detected at HCC surveillance. CEUS is also useful to differentiate malignant and benign venous thrombosis and to guide and monitor the local ablation therapy for HCC. PMID:24707142

Contrast-enhanced ultrasound in the diagnosis of nodules in liver cirrhosis.

PubMed

Kim, Tae Kyoung; Jang, Hyun-Jung

2014-04-07

Contrast-enhanced ultrasound (CEUS) using microbubble contrast agents are useful for the diagnosis of the nodules in liver cirrhosis. CEUS can be used as a problem-solving method for indeterminate nodules on computed tomography (CT) or magnetic resonance imaging (MRI) or as an initial diagnostic test for small newly detected liver nodules. CEUS has unique advantages over CT and MRI including no renal excretion of contrast, real-time imaging capability, and purely intravascular contrast. Hepatocellular carcinoma (HCC) is characterized by arterial-phase hypervascularity and later washout (negative enhancement). Benign nodules such as regenerative nodules or dysplastic nodules are usually isoechoic or slightly hypoechoic in the arterial phase and isoechoic in the late phase. However, there are occasional HCC lesions with atypical enhancement including hypovascular HCC and hypervascular HCC without washout. Cholangiocarcinomas are infrequently detected during HCC surveillance and mostly show rim-like or diffuse hypervascularity followed by rapid washout. Hemangiomas are often found at HCC surveillance and are easily diagnosed by CEUS. CEUS can be effectively used in the diagnostic work-up of small nodules detected at HCC surveillance. CEUS is also useful to differentiate malignant and benign venous thrombosis and to guide and monitor the local ablation therapy for HCC.

Identifying the association between contrast enhancement pattern, surgical resection, and prognosis in anaplastic glioma patients.

PubMed

Wang, Yinyan; Wang, Kai; Wang, Jiangfei; Li, Shaowu; Ma, Jun; Dai, Jianping; Jiang, Tao

2016-04-01

Contrast enhancement observable on magnetic resonance (MR) images reflects the destructive features of malignant gliomas. This study aimed to investigate the relationship between radiologic patterns of tumor enhancement, extent of resection, and prognosis in patients with anaplastic gliomas (AGs). Clinical data from 268 patients with histologically confirmed AGs were retrospectively analyzed. Contrast enhancement patterns were classified based on preoperative T1-contrast MR images. Univariate and multivariate analyses were performed to evaluate the prognostic value of MR enhancement patterns on progression-free survival (PFS) and overall survival (OS). The pattern of tumor contrast enhancement was associated with the extent of surgical resection in AGs. A gross total resection was more likely to be achieved for AGs with focal enhancement than those with diffuse (p = 0.001) or ring-like (p = 0.024) enhancement. Additionally, patients with focal-enhanced AGs had a significantly longer PFS and OS than those with diffuse (log-rank, p = 0.025 and p = 0.031, respectively) or ring-like (log-rank, p = 0.008 and p = 0.011, respectively) enhanced AGs. Furthermore, multivariate analysis identified the pattern of tumor enhancement as a significant predictor of PFS (p = 0.016, hazard ratio [HR] = 1.485) and OS (p = 0.030, HR = 1.446). Our results suggested that the contrast enhancement pattern on preoperative MR images was associated with the extent of resection and predictive of survival outcomes in AG patients.

Rapid Simultaneous Enhancement of Visual Sensitivity and Perceived Contrast during Saccade Preparation

PubMed Central

Rolfs, Martin; Carrasco, Marisa

2012-01-01

Humans and other animals with foveate vision make saccadic eye movements to prioritize the visual analysis of behaviorally relevant information. Even before movement onset, visual processing is selectively enhanced at the target of a saccade, presumably gated by brain areas controlling eye movements. Here we assess concurrent changes in visual performance and perceived contrast before saccades, and show that saccade preparation enhances perception rapidly, altering early visual processing in a manner akin to increasing the physical contrast of the visual input. Observers compared orientation and contrast of a test stimulus, appearing briefly before a saccade, to a standard stimulus, presented previously during a fixation period. We found simultaneous progressive enhancement in both orientation discrimination performance and perceived contrast as time approached saccade onset. These effects were robust as early as 60 ms after the eye movement was cued, much faster than the voluntary deployment of covert attention (without eye movements), which takes ~300 ms. Our results link the dynamics of saccade preparation, visual performance, and subjective experience and show that upcoming eye movements alter visual processing by increasing the signal strength. PMID:23035086

Stochastic HKMDHE: A multi-objective contrast enhancement algorithm

NASA Astrophysics Data System (ADS)

Pratiher, Sawon; Mukhopadhyay, Sabyasachi; Maity, Srideep; Pradhan, Asima; Ghosh, Nirmalya; Panigrahi, Prasanta K.

2018-02-01

This contribution proposes a novel extension of the existing `Hyper Kurtosis based Modified Duo-Histogram Equalization' (HKMDHE) algorithm, for multi-objective contrast enhancement of biomedical images. A novel modified objective function has been formulated by joint optimization of the individual histogram equalization objectives. The optimal adequacy of the proposed methodology with respect to image quality metrics such as brightness preserving abilities, peak signal-to-noise ratio (PSNR), Structural Similarity Index (SSIM) and universal image quality metric has been experimentally validated. The performance analysis of the proposed Stochastic HKMDHE with existing histogram equalization methodologies like Global Histogram Equalization (GHE) and Contrast Limited Adaptive Histogram Equalization (CLAHE) has been given for comparative evaluation.

Contrast-enhanced CT- and MRI-based perfusion assessment for pulmonary diseases: basics and clinical applications

PubMed Central

Ohno, Yoshiharu; Koyama, Hisanobu; Lee, Ho Yun; Miura, Sachiko; Yoshikawa, Takeshi; Sugimura, Kazuro

2016-01-01

Assessment of regional pulmonary perfusion as well as nodule and tumor perfusions in various pulmonary diseases are currently performed by means of nuclear medicine studies requiring radioactive macroaggregates, dual-energy computed tomography (CT), and dynamic first-pass contrast-enhanced perfusion CT techniques and unenhanced and dynamic first-pass contrast enhanced perfusion magnetic resonance imaging (MRI), as well as time-resolved three-dimensional or four-dimensional contrast-enhanced magnetic resonance angiography (MRA). Perfusion scintigraphy, single-photon emission tomography (SPECT) and SPECT fused with CT have been established as clinically available scintigraphic methods; however, they are limited by perfusion information with poor spatial resolution and other shortcomings. Although positron emission tomography with 15O water can measure absolute pulmonary perfusion, it requires a cyclotron for generation of a tracer with an extremely short half-life (2 min), and can only be performed for academic purposes. Therefore, clinicians are concentrating their efforts on the application of CT-based and MRI-based quantitative and qualitative perfusion assessment to various pulmonary diseases. This review article covers 1) the basics of dual-energy CT and dynamic first-pass contrast-enhanced perfusion CT techniques, 2) the basics of time-resolved contrast-enhanced MRA and dynamic first-pass contrast-enhanced perfusion MRI, and 3) clinical applications of contrast-enhanced CT- and MRI-based perfusion assessment for patients with pulmonary nodule, lung cancer, and pulmonary vascular diseases. We believe that these new techniques can be useful in routine clinical practice for not only thoracic oncology patients, but also patients with different pulmonary vascular diseases. PMID:27523813

Correcting speckle contrast at small speckle size to enhance signal to noise ratio for laser speckle contrast imaging.

PubMed

Qiu, Jianjun; Li, Yangyang; Huang, Qin; Wang, Yang; Li, Pengcheng

2013-11-18

In laser speckle contrast imaging, it was usually suggested that speckle size should exceed two camera pixels to eliminate the spatial averaging effect. In this work, we show the benefit of enhancing signal to noise ratio by correcting the speckle contrast at small speckle size. Through simulations and experiments, we demonstrated that local speckle contrast, even at speckle size much smaller than one pixel size, can be corrected through dividing the original speckle contrast by the static speckle contrast. Moreover, we show a 50% higher signal to noise ratio of the speckle contrast image at speckle size below 0.5 pixel size than that at speckle size of two pixels. These results indicate the possibility of selecting a relatively large aperture to simultaneously ensure sufficient light intensity and high accuracy and signal to noise ratio, making the laser speckle contrast imaging more flexible.

Contrast-enhanced optical coherence tomography with picomolar sensitivity for functional in vivo imaging

NASA Astrophysics Data System (ADS)

Liba, Orly; Sorelle, Elliott D.; Sen, Debasish; de La Zerda, Adam

2016-03-01

Optical Coherence Tomography (OCT) enables real-time imaging of living tissues at cell-scale resolution over millimeters in three dimensions. Despite these advantages, functional biological studies with OCT have been limited by a lack of exogenous contrast agents that can be distinguished from tissue. Here we report an approach to functional OCT imaging that implements custom algorithms to spectrally identify unique contrast agents: large gold nanorods (LGNRs). LGNRs exhibit 110-fold greater spectral signal per particle than conventional GNRs, which enables detection of individual LGNRs in water and concentrations as low as 250 pM in the circulation of living mice. This translates to ~40 particles per imaging voxel in vivo. Unlike previous implementations of OCT spectral detection, the methods described herein adaptively compensate for depth and processing artifacts on a per sample basis. Collectively, these methods enable high-quality noninvasive contrast-enhanced imaging of OCT in living subjects, including detection of tumor microvasculature at twice the depth achievable with conventional OCT. Additionally, multiplexed detection of spectrally-distinct LGNRs was demonstrated to observe discrete patterns of lymphatic drainage and identify individual lymphangions and lymphatic valve functional states. These capabilities provide a powerful platform for molecular imaging and characterization of tissue noninvasively at cellular resolution, called MOZART.

High Atomic Number Contrast Media Offer Potential for Radiation Dose Reduction in Contrast-Enhanced Computed Tomography.

PubMed

Roessler, Ann-Christin; Hupfer, Martin; Kolditz, Daniel; Jost, Gregor; Pietsch, Hubertus; Kalender, Willi A

2016-04-01

Spectral optimization of x-ray computed tomography (CT) has led to substantial radiation dose reduction in contrast-enhanced CT studies using standard iodinated contrast media. The purpose of this study was to analyze the potential for further dose reduction using high-atomic-number elements such as hafnium and tungsten. As in previous studies, spectra were determined for which the patient dose necessary to provide a given contrast-to-noise ratio (CNR) is minimized. We used 2 different quasi-anthropomorphic phantoms representing the liver cross-section of a normal adult and an obese adult patient with the lateral widths of 360 and 460 mm and anterior-posterior heights of 200 and 300 mm, respectively. We simulated and measured on 2 different scanners with x-ray spectra from 80 to 140 kV and from 70 to 150 kV, respectively. We determined the contrast for iodine-, hafnium-, and tungsten-based contrast media, the noise, and 3-dimensional dose distributions at all available tube voltages by measurements and by simulations. The dose-weighted CNR was determined as optimization parameter. Simulations and measurements were in good agreement regarding their dependence on energy for all parameters investigated. Hafnium provided the best performance for normal and for obese patient phantoms, indicating a dose reduction potential of 30% for normal and 50% for obese patients at 120 kV compared with iodine; this advantage increased further with higher kV values. Dose-weighted CNR values for tungsten were always slightly below the hafnium results. Iodine proved to be the superior choice at voltage values of 80 kV and below. Hafnium and tungsten both seem to be candidates for contrast-medium-enhanced CT of normal and obese adult patients with strongly reduced radiation dose at unimpaired image quality. Computed tomography examinations of obese patients will decrease in dose for higher kV values.

A novel approach to quantify cybersecurity for electric power systems

NASA Astrophysics Data System (ADS)

Kaster, Paul R., Jr.

Electric Power grid cybersecurity is a topic gaining increased attention in academia, industry, and government circles, yet a method of quantifying and evaluating a system's security is not yet commonly accepted. In order to be useful, a quantification scheme must be able to accurately reflect the degree to which a system is secure, simply determine the level of security in a system using real-world values, model a wide variety of attacker capabilities, be useful for planning and evaluation, allow a system owner to publish information without compromising the security of the system, and compare relative levels of security between systems. Published attempts at quantifying cybersecurity fail at one or more of these criteria. This document proposes a new method of quantifying cybersecurity that meets those objectives. This dissertation evaluates the current state of cybersecurity research, discusses the criteria mentioned previously, proposes a new quantification scheme, presents an innovative method of modeling cyber attacks, demonstrates that the proposed quantification methodology meets the evaluation criteria, and proposes a line of research for future efforts.

Detection of cavernous transformation of the portal vein by contrast-enhanced ultrasound.

PubMed

Hwang, Misun; Thimm, Matthew A; Guerrerio, Anthony L

2018-06-01

Cavernous transformation of the portal vein can be missed on color Doppler exam or arterial phase cross-sectional imaging due to their slow flow and delayed enhancement. Contrast-enhanced ultrasound (CEUS) offers many advantages over other imaging techniques and can be used to successfully detect cavernous transformations of the portal vein. A 10-month-old female was followed for repeat episodes of hematemesis. Computed tomography angiography (CTA) and magnetic resonance arteriogram (MRA) and portal venography were performed. Color Doppler exam of the portal vein was performed followed by administration of Lumason, a microbubble US contrast agent. Magnetic resonance arteriogram, CTA, and color Doppler exam at the time of initial presentation was unremarkable without obvious vascular malformation within the limits of motion degraded exam. At 8-month follow-up, esophagogastroduodenoscopy revealed a vascular malformation in the distal esophagus which was sclerosed. At 6 month after sclerosis of the lesion, portal venography revealed occlusion of the portal vein with extensive collateralization. Color Doppler revealed subtle hyperarterialization and periportal collaterals. CEUS following color Doppler exam demonstrated extensive enhancement of periportal collaterals. Repeat color Doppler after contrast administration demonstrated extensive Doppler signal in the collateral vessels, suggestive of cavernous transformation. We describe a case of cavernous transformation of the portal vein missed on initial color Doppler, CTA and MRA, but detected with contrast-enhanced ultrasound technique.

Morton neuroma: evaluation with MR imaging performed with contrast enhancement and fat suppression.

PubMed

Terk, M R; Kwong, P K; Suthar, M; Horvath, B C; Colletti, P M

1993-10-01

To evaluate clinically suspected Morton neuroma with contrast material-enhanced magnetic resonance (MR) images. Fifteen patients with clinically suspected Morton neuroma underwent examination with conventional T1- and T2-weighted MR imaging and a combination of fat suppression and administration of gadopentetate dimeglumine. A T1-weighted spectral presaturation with inversion recovery sequence was used for fat suppression. In six patients, a tumor that conformed to the clinical findings was seen in the interdigital space; surgical findings in these patients correlated closely with the imaging findings in all patients. Patients without positive findings on MR images tended to have less typical clinical findings and received nonsurgical treatment. In all patients, the lesions were best depicted with the combination of contrast-enhanced imaging and fat suppression; conventional MR images either entirely failed to demonstrate the lesions or demonstrated the lesions less clearly. In patients who need imaging confirmation of a clinically suspected Morton neuroma, the combination of fat suppression and contrast enhancement provides reliable high-contrast images.

FDG-Avid Portal Vein Tumor Thrombosis from Hepatocellular Carcinoma in Contrast-Enhanced FDG PET/CT

PubMed Central

Nguyen, Xuan Canh; Nguyen, Dinh Song Huy; Ngo, Van Tan; Maurea, Simone

2015-01-01

Objective(s): In this study, we aimed to describe the characteristics of portal vein tumor thrombosis (PVTT), complicating hepatocellular carcinoma (HCC) in contrast-enhanced FDG PET/CT scan. Methods: In this retrospective study, 9 HCC patients with FDG-avid PVTT were diagnosed by contrast-enhanced fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT), which is a combination of dynamic liver CT scan, multiphase imaging, and whole-body PET scan. PET and CT DICOM images of patients were imported into the PET/CT imaging system for the re-analysis of contrast enhancement and FDG uptake in thrombus, the diameter of the involved portal vein, and characteristics of liver tumors and metastasis. Results: Two patients with previously untreated HCC and 7 cases with previously treated HCC had FDG-avid PVTT in contrast-enhanced FDG PET/CT scan. During the arterial phase of CT scan, portal vein thrombus showed contrast enhancement in 8 out of 9 patients (88.9%). PET scan showed an increased linear FDG uptake along the thrombosed portal vein in all patients. The mean greatest diameter of thrombosed portal veins was 1.8 ± 0.2 cm, which was significantly greater than that observed in normal portal veins (P<0.001). FDG uptake level in portal vein thrombus was significantly higher than that of blood pool in the reference normal portal vein (P=0.001). PVTT was caused by the direct extension of liver tumors. All patients had visible FDG-avid liver tumors in contrast-enhanced images. Five out of 9 patients (55.6%) had no extrahepatic metastasis, 3 cases (33.3%) had metastasis of regional lymph nodes, and 1 case (11.1%) presented with distant metastasis. The median estimated survival time of patients was 5 months. Conclusion: The intraluminal filling defect consistent with thrombous within the portal vein, expansion of the involved portal vein, contrast enhancement, and linear increased FDG uptake of the thrombus extended from liver tumor are findings of FDG

Diffraction enhance x-ray imaging for quantitative phase contrast studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agrawal, A. K.; Singh, B., E-mail: balwants@rrcat.gov.in; Kashyap, Y. S.

2016-05-23

Conventional X-ray imaging based on absorption contrast permits limited visibility of feature having small density and thickness variations. For imaging of weakly absorbing material or materials possessing similar densities, a novel phase contrast imaging techniques called diffraction enhanced imaging has been designed and developed at imaging beamline Indus-2 RRCAT Indore. The technique provides improved visibility of the interfaces and show high contrast in the image forsmall density or thickness gradients in the bulk. This paper presents basic principle, instrumentation and analysis methods for this technique. Initial results of quantitative phase retrieval carried out on various samples have also been presented.

Compact self-powered synchronous energy extraction circuit design with enhanced performance

NASA Astrophysics Data System (ADS)

Liu, Weiqun; Zhao, Caiyou; Badel, Adrien; Formosa, Fabien; Zhu, Qiao; Hu, Guangdi

2018-04-01

Synchronous switching circuit is viewed as an effective solution of enhancing the generator’s performance and providing better adaptability for load variations. A critical issue for these synchronous switching circuits is the self-powered realization. In contrast with other methods, the electronic breaker possesses the advantage of simplicity and reliability. However, beside the energy consumption of the electronic breakers, the parasitic capacitance decreases the available piezoelectric voltage. In this technical note, a new compact design of the self-powered switching circuit using electronic breaker is proposed. The envelope diodes are excluded and only a single envelope capacitor is used. The parasitic capacitance is reduced to half with boosted performance while the components are reduced with cost saved.

Task-based strategy for optimized contrast enhanced breast imaging: analysis of six imaging techniques for mammography and tomosynthesis

NASA Astrophysics Data System (ADS)

Ikejimba, Lynda; Kiarashi, Nooshin; Lin, Yuan; Chen, Baiyu; Ghate, Sujata V.; Zerhouni, Moustafa; Samei, Ehsan; Lo, Joseph Y.

2012-03-01

Digital breast tomosynthesis (DBT) is a novel x-ray imaging technique that provides 3D structural information of the breast. In contrast to 2D mammography, DBT minimizes tissue overlap potentially improving cancer detection and reducing number of unnecessary recalls. The addition of a contrast agent to DBT and mammography for lesion enhancement has the benefit of providing functional information of a lesion, as lesion contrast uptake and washout patterns may help differentiate between benign and malignant tumors. This study used a task-based method to determine the optimal imaging approach by analyzing six imaging paradigms in terms of their ability to resolve iodine at a given dose: contrast enhanced mammography and tomosynthesis, temporal subtraction mammography and tomosynthesis, and dual energy subtraction mammography and tomosynthesis. Imaging performance was characterized using a detectability index d', derived from the system task transfer function (TTF), an imaging task, iodine contrast, and the noise power spectrum (NPS). The task modeled a 5 mm lesion containing iodine concentrations between 2.1 mg/cc and 8.6 mg/cc. TTF was obtained using an edge phantom, and the NPS was measured over several exposure levels, energies, and target-filter combinations. Using a structured CIRS phantom, d' was generated as a function of dose and iodine concentration. In general, higher dose gave higher d', but for the lowest iodine concentration and lowest dose, dual energy subtraction tomosynthesis and temporal subtraction tomosynthesis demonstrated the highest performance.

Multipurpose contrast enhancement on epiphyseal plates and ossification centers for bone age assessment

PubMed Central

2013-01-01

Background The high variations of background luminance, low contrast and excessively enhanced contrast of hand bone radiograph often impede the bone age assessment rating system in evaluating the degree of epiphyseal plates and ossification centers development. The Global Histogram equalization (GHE) has been the most frequently adopted image contrast enhancement technique but the performance is not satisfying. A brightness and detail preserving histogram equalization method with good contrast enhancement effect has been a goal of much recent research in histogram equalization. Nevertheless, producing a well-balanced histogram equalized radiograph in terms of its brightness preservation, detail preservation and contrast enhancement is deemed to be a daunting task. Method In this paper, we propose a novel framework of histogram equalization with the aim of taking several desirable properties into account, namely the Multipurpose Beta Optimized Bi-Histogram Equalization (MBOBHE). This method performs the histogram optimization separately in both sub-histograms after the segmentation of histogram using an optimized separating point determined based on the regularization function constituted by three components. The result is then assessed by the qualitative and quantitative analysis to evaluate the essential aspects of histogram equalized image using a total of 160 hand radiographs that are implemented in testing and analyses which are acquired from hand bone online database. Result From the qualitative analysis, we found that basic bi-histogram equalizations are not capable of displaying the small features in image due to incorrect selection of separating point by focusing on only certain metric without considering the contrast enhancement and detail preservation. From the quantitative analysis, we found that MBOBHE correlates well with human visual perception, and this improvement shortens the evaluation time taken by inspector in assessing the bone age. Conclusions

A comparative study on preprocessing techniques in diabetic retinopathy retinal images: illumination correction and contrast enhancement.

PubMed

Rasta, Seyed Hossein; Partovi, Mahsa Eisazadeh; Seyedarabi, Hadi; Javadzadeh, Alireza

2015-01-01

To investigate the effect of preprocessing techniques including contrast enhancement and illumination correction on retinal image quality, a comparative study was carried out. We studied and implemented a few illumination correction and contrast enhancement techniques on color retinal images to find out the best technique for optimum image enhancement. To compare and choose the best illumination correction technique we analyzed the corrected red and green components of color retinal images statistically and visually. The two contrast enhancement techniques were analyzed using a vessel segmentation algorithm by calculating the sensitivity and specificity. The statistical evaluation of the illumination correction techniques were carried out by calculating the coefficients of variation. The dividing method using the median filter to estimate background illumination showed the lowest Coefficients of variations in the red component. The quotient and homomorphic filtering methods after the dividing method presented good results based on their low Coefficients of variations. The contrast limited adaptive histogram equalization increased the sensitivity of the vessel segmentation algorithm up to 5% in the same amount of accuracy. The contrast limited adaptive histogram equalization technique has a higher sensitivity than the polynomial transformation operator as a contrast enhancement technique for vessel segmentation. Three techniques including the dividing method using the median filter to estimate background, quotient based and homomorphic filtering were found as the effective illumination correction techniques based on a statistical evaluation. Applying the local contrast enhancement technique, such as CLAHE, for fundus images presented good potentials in enhancing the vasculature segmentation.

Improved wrist pannus volume measurement from contrast-enhanced MRI in rheumatoid arthritis using shuffle transform.

PubMed

Xanthopoulos, Emily; Hutchinson, Charles E; Adams, Judith E; Bruce, Ian N; Nash, Anthony F P; Holmes, Andrew P; Taylor, Christopher J; Waterton, John C

2007-01-01

Contrast-enhanced MRI is of value in assessing rheumatoid pannus in the hand, but the images are not always easy to quantitate. To develop and evaluate an improved measurement of volume of enhancing pannus (VEP) in the hand in human rheumatoid arthritis (RA). MR images of the hand and wrist were obtained for 14 patients with RA at 0, 1 and 13 weeks. Volume of enhancing pannus was measured on images created by subtracting precontrast T1-weighted images from contrast-enhanced T1-weighted images using a shuffle transformation technique. Maximum intensity projection (MIP) and 3D volume rendering of the images were used as a guide to identify the pannus and any contrast-enhanced veins. Visualisation of pannus was much improved following the shuffle transform. Between 0 weeks and 1 week, the mean value of the within-subject coefficient of variation (CoV) was 0.13 and the estimated total CoV was 0.15. There was no evidence of significant increased variability within the 13-week interval for the complete sample of patients. Volume of enhancing pannus can be measured reproducibly in the rheumatoid hand using 3D contrast-enhanced MRI and shuffle transform.

The Application of Contrast Media for In Vivo Feature Enhancement in X-Ray Computed Tomography of Soil-Grown Plant Roots.

PubMed

Keyes, Samuel D; Gostling, Neil J; Cheung, Jessica H; Roose, Tiina; Sinclair, Ian; Marchant, Alan

2017-06-01

The use of in vivo X-ray microcomputed tomography (μCT) to study plant root systems has become routine, but is often hampered by poor contrast between roots, soil, soil water, and soil organic matter. In clinical radiology, imaging of poorly contrasting regions is frequently aided by the use of radio-opaque contrast media. In this study, we present evidence for the utility of iodinated contrast media (ICM) in the study of plant root systems using μCT. Different dilutions of an ionic and nonionic ICM (Gastrografin 370 and Niopam 300) were perfused into the aerial vasculature of juvenile pea plants via a leaf flap (Pisum sativum). The root systems were imaged via μCT, and a variety of image-processing approaches used to quantify and compare the magnitude of the contrast enhancement between different regions. Though the treatment did not appear to significantly aid extraction of full root system architectures from the surrounding soil, it did allow the xylem and phloem units of seminal roots and the vascular morphology within rhizobial nodules to be clearly visualized. The nonionic, low-osmolality contrast agent Niopam appeared to be well tolerated by the plant, whereas Gastrografin showed evidence of toxicity. In summary, the use of iodine-based contrast media allows usually poorly contrasting root structures to be visualized nondestructively using X-ray μCT. In particular, the vascular structures of roots and rhizobial nodules can be clearly visualized in situ.

Local gray level S-curve transformation - A generalized contrast enhancement technique for medical images.

PubMed

Gandhamal, Akash; Talbar, Sanjay; Gajre, Suhas; Hani, Ahmad Fadzil M; Kumar, Dileep

2017-04-01

Most medical images suffer from inadequate contrast and brightness, which leads to blurred or weak edges (low contrast) between adjacent tissues resulting in poor segmentation and errors in classification of tissues. Thus, contrast enhancement to improve visual information is extremely important in the development of computational approaches for obtaining quantitative measurements from medical images. In this research, a contrast enhancement algorithm that applies gray-level S-curve transformation technique locally in medical images obtained from various modalities is investigated. The S-curve transformation is an extended gray level transformation technique that results into a curve similar to a sigmoid function through a pixel to pixel transformation. This curve essentially increases the difference between minimum and maximum gray values and the image gradient, locally thereby, strengthening edges between adjacent tissues. The performance of the proposed technique is determined by measuring several parameters namely, edge content (improvement in image gradient), enhancement measure (degree of contrast enhancement), absolute mean brightness error (luminance distortion caused by the enhancement), and feature similarity index measure (preservation of the original image features). Based on medical image datasets comprising 1937 images from various modalities such as ultrasound, mammograms, fluorescent images, fundus, X-ray radiographs and MR images, it is found that the local gray-level S-curve transformation outperforms existing techniques in terms of improved contrast and brightness, resulting in clear and strong edges between adjacent tissues. The proposed technique can be used as a preprocessing tool for effective segmentation and classification of tissue structures in medical images. Copyright © 2017 Elsevier Ltd. All rights reserved.

Image contrast enhancement based on a local standard deviation model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Dah-Chung; Wu, Wen-Rong

1996-12-31

The adaptive contrast enhancement (ACE) algorithm is a widely used image enhancement method, which needs a contrast gain to adjust high frequency components of an image. In the literature, the gain is usually inversely proportional to the local standard deviation (LSD) or is a constant. But these cause two problems in practical applications, i.e., noise overenhancement and ringing artifact. In this paper a new gain is developed based on Hunt`s Gaussian image model to prevent the two defects. The new gain is a nonlinear function of LSD and has the desired characteristic emphasizing the LSD regions in which details aremore » concentrated. We have applied the new ACE algorithm to chest x-ray images and the simulations show the effectiveness of the proposed algorithm.« less

Textural analysis of early-phase spatiotemporal changes in contrast enhancement of breast lesions imaged with an ultrafast DCE-MRI protocol.

PubMed

Milenković, Jana; Dalmış, Mehmet Ufuk; Žgajnar, Janez; Platel, Bram

2017-09-01

New ultrafast view-sharing sequences have enabled breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to be performed at high spatial and temporal resolution. The aim of this study is to evaluate the diagnostic potential of textural features that quantify the spatiotemporal changes of the contrast-agent uptake in computer-aided diagnosis of malignant and benign breast lesions imaged with high spatial and temporal resolution DCE-MRI. The proposed approach is based on the textural analysis quantifying the spatial variation of six dynamic features of the early-phase contrast-agent uptake of a lesion's largest cross-sectional area. The textural analysis is performed by means of the second-order gray-level co-occurrence matrix, gray-level run-length matrix and gray-level difference matrix. This yields 35 textural features to quantify the spatial variation of each of the six dynamic features, providing a feature set of 210 features in total. The proposed feature set is evaluated based on receiver operating characteristic (ROC) curve analysis in a cross-validation scheme for random forests (RF) and two support vector machine classifiers, with linear and radial basis function (RBF) kernel. Evaluation is done on a dataset with 154 breast lesions (83 malignant and 71 benign) and compared to a previous approach based on 3D morphological features and the average and standard deviation of the same dynamic features over the entire lesion volume as well as their average for the smaller region of the strongest uptake rate. The area under the ROC curve (AUC) obtained by the proposed approach with the RF classifier was 0.8997, which was significantly higher (P = 0.0198) than the performance achieved by the previous approach (AUC = 0.8704) on the same dataset. Similarly, the proposed approach obtained a significantly higher result for both SVM classifiers with RBF (P = 0.0096) and linear kernel (P = 0.0417) obtaining AUC of 0.8876 and 0.8548, respectively

Pulmonary transit time measurement by contrast-enhanced ultrasound in left ventricular dyssynchrony.

PubMed

Herold, Ingeborg H F; Saporito, Salvatore; Mischi, Massimo; van Assen, Hans C; Bouwman, R Arthur; de Lepper, Anouk G W; van den Bosch, Harrie C M; Korsten, Hendrikus H M; Houthuizen, Patrick

2016-06-01

Pulmonary transit time (PTT) is an indirect measure of preload and left ventricular function, which can be estimated using the indicator dilution theory by contrast-enhanced ultrasound (CEUS). In this study, we first assessed the accuracy of PTT-CEUS by comparing it with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Secondly, we tested the hypothesis that PTT-CEUS correlates with the severity of heart failure, assessed by MRI and N-terminal pro-B-type natriuretic peptide (NT-proBNP). Twenty patients referred to our hospital for cardiac resynchronization therapy (CRT) were enrolled. DCE-MRI, CEUS, and NT-proBNP measurements were performed within an hour. Mean transit time (MTT) was obtained by estimating the time evolution of indicator concentration within regions of interest drawn in the right and left ventricles in video loops of DCE-MRI and CEUS. PTT was estimated as the difference of the left and right ventricular MTT. Normalized PTT (nPTT) was obtained by multiplication of PTT with the heart rate. Mean PTT-CEUS was 10.5±2.4s and PTT-DCE-MRI was 10.4±2.0s (P=0.88). The correlations of PTT and nPTT by CEUS and DCE-MRI were strong; r=0.75 (P=0.0001) and r=0.76 (P=0.0001), respectively. Bland-Altman analysis revealed a bias of 0.1s for PTT. nPTT-CEUS correlated moderately with left ventricle volumes. The correlations for PTT-CEUS and nPTT-CEUS were moderate to strong with NT-proBNP; r=0.54 (P=0.022) and r=0.68 (P=0.002), respectively. (n)PTT-CEUS showed strong agreement with that by DCE-MRI. Given the good correlation with NT-proBNP level, (n)PTT-CEUS may provide a novel, clinically feasible measure to quantify the severity of heart failure. NCT01735838. © 2016 The authors.

Delayed Enhancement of Ascites After IV Contrast Material Administration at CT: Time Course and Clinical Correlation

PubMed Central

Benedetti, Nancy; Aslam, Rizwan; Wang, Zhen J.; Joe, Bonnie N.; Fu, Yanjun; Yee, Judy; Yeh, Benjamin M.

2010-01-01

OBJECTIVE The objective of our study was to determine the prevalence and clinical predictors of delayed contrast enhancement of ascites. MATERIALS AND METHODS In this retrospective study, 132 consecutive patients with ascites who underwent repeated abdominopelvic CT examinations performed within 7 days of each other were identified. These patients included 112 patients who received and 20 who did not receive IV contrast material at the initial CT examination. For each examination, we recorded the CT attenuation of the ascites. For the follow-up scan, the presence of delayed enhancement of ascites was defined as an increase in CT attenuation > 10 HU over baseline. The Fisher’s exact test, unpaired Student’s t test, and logistic regression were used to determine predictors of delayed enhancement of ascites. RESULTS A threshold increase in the attenuation of ascites by > 10 HU or more between the initial and follow-up CT examinations occurred only when IV contrast material was given with the initial examination. The increased attenuation was due to delayed contrast enhancement of ascites and occurred in 15 of the 112 patients (13%). Of the 16 patients scanned less than 1 day apart, 10 (63%) showed delayed enhancement of ascites. Delayed enhancement was not observed 3 or more days after IV contrast material administration. For each 1 mg/dL increase in serum creatinine level, the likelihood of delayed enhancement of ascites increased (odds ratio, 2.02; 95% CI, 1.11–3.69). Multivariate logistic regression showed that a short time interval between examinations (p < 0.001), increased serum creatinine level (p < 0.001), and presence of loculated ascites (p = < 0.01) were independent predictors of the magnitude of delayed enhancement of ascites. CONCLUSION Delayed contrast enhancement of ascites occurs commonly after recent prior IV contrast material administration and should not be mistaken for hemoperitoneum or proteinaceous fluid such as pus. PMID:19696286

Measurement of myocardial extracellular volume fraction by using equilibrium contrast-enhanced CT: validation against histologic findings.

PubMed

Bandula, Steve; White, Steven K; Flett, Andrew S; Lawrence, David; Pugliese, Francesca; Ashworth, Michael T; Punwani, Shonit; Taylor, Stuart A; Moon, James C

2013-11-01

To develop and validate equilibrium contrast material-enhanced computed tomography (CT) to measure myocardial extracellular volume (ECV) fraction by using a histologic reference standard and to compare equilibrium CT with equilibrium contrast-enhanced magnetic resonance (MR) imaging. A local ethics committee approved the study, and all subjects gave fully informed written consent. An equilibrium CT protocol was developed using iohexol at 300 mg of iodine per milliliter (bolus of 1 mg per kilogram of body weight administered at a rate of 3 mL/sec, followed immediately by an infusion of 1.88 mL/kg per hour with CT imaging before and at 25 minutes after injection of bolus of contrast agent) and ECV within the myocardial septum measured using both equilibrium CT and equilibrium MR imaging in patients with severe aortic stenosis. Biopsy samples of the myocardial septum collected during valve replacement surgery were used for histologic quantification of extracellular fibrosis with picrosirius red staining. Equilibrium CT- and equilibrium MR imaging-derived ECV measurements were compared with histologically quantified fibrosis by using Pearson correlation. Agreement between equilibrium CT and equilibrium MR imaging was assessed by using Bland-Altman comparison. Twenty-three patients (16 male, seven female; mean age, 70.8 years; standard deviation, 8.3) were recruited. The mean percentage of histologic fibrosis was 18% (intersubject range, 5%-40%). There was a significant correlation between both equilibrium CT- and equilibrium MR imaging-derived ECV and percentage of histologic fibrosis (r = 0.71 [P < .001] and r = 0.84 [P < .0001], respectively). Equilibrium CT-derived ECV was significantly correlated to equilibrium MR imaging-derived ECV (r = 0.73). ECV measured by using equilibrium CT in patients with aortic stenosis correlates with histologic quantification of myocardial fibrosis and with ECV derived by using equilibrium MR imaging. RSNA, 2013

The Impact of Injector-Based Contrast Agent Administration on Bolus Shape and Magnetic Resonance Angiography Image Quality.

PubMed

Jost, Gregor; Endrikat, Jan; Pietsch, Hubertus

2017-01-01

To compare injector-based contrast agent (CA) administration with hand injection in magnetic resonance angiography (MRA). Gadobutrol was administered in 6 minipigs with 3 protocols: (a) hand injection (one senior technician), (b) hand injection (6 less-experienced technicians), and (c) power injector administration. The arterial bolus shape was quantified by test bolus measurements. A head and neck MRA was performed for quantitative and qualitative comparison of signal enhancement. A significantly shorter time to peak was observed for protocol C, whereas no significant differences between protocols were found for peak height and bolus width. However, for protocol C, these parameters showed a much lower variation. The MRA revealed a significantly higher signal-to-noise ratio for injector-based administration. A superimposed strong contrast of the jugular vein was found in 50% of the hand injections. Injector-based CA administration results in a more standardized bolus shape, a higher vascular contrast, and a more robust visualization of target vessels.

A Comparative Study on Preprocessing Techniques in Diabetic Retinopathy Retinal Images: Illumination Correction and Contrast Enhancement

PubMed Central

Rasta, Seyed Hossein; Partovi, Mahsa Eisazadeh; Seyedarabi, Hadi; Javadzadeh, Alireza

2015-01-01

To investigate the effect of preprocessing techniques including contrast enhancement and illumination correction on retinal image quality, a comparative study was carried out. We studied and implemented a few illumination correction and contrast enhancement techniques on color retinal images to find out the best technique for optimum image enhancement. To compare and choose the best illumination correction technique we analyzed the corrected red and green components of color retinal images statistically and visually. The two contrast enhancement techniques were analyzed using a vessel segmentation algorithm by calculating the sensitivity and specificity. The statistical evaluation of the illumination correction techniques were carried out by calculating the coefficients of variation. The dividing method using the median filter to estimate background illumination showed the lowest Coefficients of variations in the red component. The quotient and homomorphic filtering methods after the dividing method presented good results based on their low Coefficients of variations. The contrast limited adaptive histogram equalization increased the sensitivity of the vessel segmentation algorithm up to 5% in the same amount of accuracy. The contrast limited adaptive histogram equalization technique has a higher sensitivity than the polynomial transformation operator as a contrast enhancement technique for vessel segmentation. Three techniques including the dividing method using the median filter to estimate background, quotient based and homomorphic filtering were found as the effective illumination correction techniques based on a statistical evaluation. Applying the local contrast enhancement technique, such as CLAHE, for fundus images presented good potentials in enhancing the vasculature segmentation. PMID:25709940

Colorectal liver metastases: contrast agent diffusion coefficient for quantification of contrast enhancement heterogeneity at MR imaging.

PubMed

Jia, Guang; O'Dell, Craig; Heverhagen, Johannes T; Yang, Xiangyu; Liang, Jiachao; Jacko, Richard V; Sammet, Steffen; Pellas, Theodore; Cole, Patricia; Knopp, Michael V

2008-09-01

To describe and determine the reproducibility of a simplified model to quantitatively measure heterogeneous intralesion contrast agent diffusion in colorectal liver metastases. This HIPAA-compliant retrospective study received institutional review board approval, and written informed consent was obtained from 14 patients (mean age, 61 years +/- 9 [standard deviation]; range, 41-78 years), including 10 men (mean age, 65 years +/- 8; range, 47-78 years) and four women (mean age, 54 years +/- 9; range, 41-59 years), with colorectal liver metastases. Magnetic resonance (MR) imaging was performed twice (first baseline MR image [B(1)] and second baseline MR image [B(2)]) in a single target lesion prior to therapy. Dynamic contrast material-enhanced MR imaging was performed by using a saturation-recovery fast gradient-echo sequence. A simplified contrast agent diffusion model was proposed, and a contrast agent diffusion coefficient (CDC) was calculated. The reproducibility of the CDC measurement was evaluated by using the Bland-Altman plot and a linear regression model. The mean CDC was 0.22 mm(2)/sec (range, 0.01-0.73 mm(2)/sec) on B(1) and 0.24 mm(2)/sec (range, 0.01-0.71 mm(2)/sec) on B(2), with an intraclass correlation coefficient of 0.91 (P < .0001). Bland-Altman plot showed good agreement, with a mean difference in measurement pairs of 0.017 mm(2)/sec +/- 0.096. The slope from the linear regression model was 0.89 (95% confidence interval: 0.63, 1.15) and the intercept was 0.01 (95% confidence interval: -0.08, 0.09). The CDC enables a quantitative description of contrast enhancement heterogeneity in lesions. Given the high reproducibility of the CDC metric, CDC appears promising for further qualification as an imaging biomarker of change measurement in response assessment. http://radiology.rsnajnls.org/cgi/content/full/248/3/901/DC1. RSNA, 2008

Prognostic value of contrast-enhanced MR mammography in patients with breast cancer.

PubMed

Fischer, U; Kopka, L; Brinck, U; Korabiowska, M; Schauer, A; Grabbe, E

1997-01-01

The objective of this study was to evaluate the prognostic value of contrast-enhanced MR mammography in patients with breast cancer. A total of 190 patients with breast cancer (37 noninvasive carcinomas, 153 invasive carcinomas) underwent dynamic contrast-enhanced MR mammography preoperatively. Using 1.5-T unit, T1-weighted sequences (2D FLASH) were obtained repeatedly one time before and five times after IV administration of 0.1 mmol gadopentetate-dimeglumine per kilogram body weight. The findings on MR imaging were correlated with histopathologically defined prognostic factors (histological type, tumor size, tumor grading, metastasis in lymph nodes). In addition, immunohistochemically defined prognostic factors (c-erbB-1, c-erbB-2, p53, Ki-67) were correlated with the signal increase on MR mammogram in 40 patients. There was no significant correlation between the findings on MR mammography and the histopathological type of carcinoma, the grading, and the lymphonodular status. Noninvasive carcinomas showed a higher rate of moderate (38 %) or low (27 %) enhancement on MR imaging than invasive carcinomas (6 and 3 %). The results on MR mammography and the results of immunohistochemical stainings did not correlate significantly. Noninvasive carcinomas showed significantly lower enhancement than invasive carcinomas. However, the signal behavior of contrast-enhanced MR mammography is not related to established histopathological prognostic parameters as subtyping, grading, nodal status, and the expression of certain oncogenes/tumor suppressor genes.

Application of a biodegradable macromolecular contrast agent in dynamic contrast enhanced MRI for assessing the efficacy of indocyanine green enhanced photothermal cancer therapy

PubMed Central

Feng, Yi; Emerson, Lyska; Jeong, Eun-Kee; Parker, Dennis L.; Lu, Zheng-Rong

2009-01-01

Purpose To investigate the effectiveness of a polydisulfide-based biodegradable macromolecular contrast agent, (Gd-DTPA)-cystamine copolymers (GDCC), in assessing the efficacy of indocyanine green enhanced photothermal cancer therapy using dynamic contrast enhanced MRI (DCE-MRI). Materials and Methods Breast cancer xenografts in mice were injected with indocyanine green and irradiated with laser. The efficacy was assessed using DCE-MRI with GDCC of 40 KDa (GDCC-40) at 4 hours and 7 days after the treatment. The uptake of GDCC-40 by the tumors was fit to a two-compartment model to obtain tumor vascular parameters, including fractional plasma volume (fPV), endothelium transfer coefficient (KPS), and permeability surface area product (PS). Results GDCC-40 resulted in similar tumor vascular parameters at three doses with larger standard deviations at lower doses. The values of fPV, KPS and PS of the treated tumors were smaller (p < 0.05) than those of untreated tumors at 4 hours after the treatment and recovered to pretreatment values (p > 0.05) at 7 days after the treatment. Conclusion DCE-MRI with GDCC-40 is effective for assessing tumor early response to dye-enhanced photothermal therapy and detecting tumor relapse after the treatment. GDCC-40 has a potential to non-invasively monitor anticancer therapies with DCE-MRI. PMID:19629979

Rest-Stress Limb Perfusion Imaging in Humans with Contrast Ultrasound Using Intermediate-Power Imaging and Microbubbles Resistant to Inertial Cavitation.

PubMed

Davidson, Brian P; Hodovan, James; Belcik, J Todd; Moccetti, Federico; Xie, Aris; Ammi, Azzdine Y; Lindner, Jonathan R

2017-05-01

Contrast-enhanced ultrasound (CEU) limb perfusion imaging is a promising approach for evaluating peripheral artery disease (PAD). However, low signal enhancement in skeletal muscle has necessitated high-power intermittent imaging algorithms, which are not clinically feasible. We hypothesized that CEU using a combination of intermediate power and a contrast agent resistant to inertial cavitation would allow real-time limb stress perfusion imaging. In normal volunteers, CEU of the calf skeletal muscle was performed on separate days with Sonazoid, Optison, or Definity. Progressive reduction in the ultrasound pulsing interval was used to assess the balance between signal enhancement and agent destruction at escalating mechanical indices (MI, 0.1-0.4). Real-time perfusion imaging at MI 0.1-0.4 using postdestructive replenishment kinetics was performed at rest and during 25 W plantar flexion contractile exercise. For Optison, limb perfusion imaging was unreliable at rest due to very low signal enhancement generated at all MIs and was possible during exercise-induced hyperemia only at MI 0.1 due to agent destruction at higher MIs. For Definity, signal intensity progressively increased with MI but was offset by microbubble destruction, which resulted in modest signal enhancement during CEU perfusion imaging and distortion of replenishment curves at MI ≥ 0.2. For Sonazoid, there strong signal enhancement at MI ≥ 0.2, with little destruction detected only at MI 0.4. Accordingly, high signal intensity and nondistorted perfusion imaging was possible at MI 0.2-0.3 and detected an 8.0- ± 5.7-fold flow reserve. Rest-stress limb perfusion imaging in humans with real-time CEU, which requires only seconds to perform, is possible using microbubbles with viscoelastic properties that produce strong nonlinear signal generation without destruction at intermediate acoustic pressures. Copyright © 2016 American Society of Echocardiography. All rights reserved.

Enhancement tuning and control for high dynamic range images in multi-scale locally adaptive contrast enhancement algorithms

NASA Astrophysics Data System (ADS)

Cvetkovic, Sascha D.; Schirris, Johan; de With, Peter H. N.

2009-01-01

For real-time imaging in surveillance applications, visibility of details is of primary importance to ensure customer confidence. If we display High Dynamic-Range (HDR) scenes whose contrast spans four or more orders of magnitude on a conventional monitor without additional processing, results are unacceptable. Compression of the dynamic range is therefore a compulsory part of any high-end video processing chain because standard monitors are inherently Low- Dynamic Range (LDR) devices with maximally two orders of display dynamic range. In real-time camera processing, many complex scenes are improved with local contrast enhancements, bringing details to the best possible visibility. In this paper, we show how a multi-scale high-frequency enhancement scheme, in which gain is a non-linear function of the detail energy, can be used for the dynamic range compression of HDR real-time video camera signals. We also show the connection of our enhancement scheme to the processing way of the Human Visual System (HVS). Our algorithm simultaneously controls perceived sharpness, ringing ("halo") artifacts (contrast) and noise, resulting in a good balance between visibility of details and non-disturbance of artifacts. The overall quality enhancement, suitable for both HDR and LDR scenes, is based on a careful selection of the filter types for the multi-band decomposition and a detailed analysis of the signal per frequency band.

Enhancing MRI of liver metastases with a zwitterionized biodegradable dendritic contrast agent.

PubMed

Zhou, Xiaoxuan; Ye, Mingzhou; Han, Yuxin; Tang, Jianbin; Qian, Yue; Hu, Hongjie; Shen, Youqing

2017-07-25

Metastasis is the main reason for cancer-associated mortality, and accurate diagnostic imaging of metastases is critical for the clinical administration and tailoring personalized treatments for metastatic tumors. However, magnetic resonance imaging of metastases in the liver is impeded by its low sensitivity because the currently used contrast agents accumulate in hepatocytes and Kupffer cells instead of cancer cells. Herein, a 4 th generation zwitterionized biodegradable dendritic contrast agent (DCA) with a size of ca. 9 nm and a longitudinal relaxivity of 15.7 mM -1 s -1 in terms of Gd was synthesized and used to enhance the MRI of liver metastasis. The DCA could remarkably enhance the MRI of metastasized tumors in the liver, because it could simultaneously reduce the background signal in the liver by avoiding uptake by hepatocytes and Kupffer cells through the zwitterionization and increase the signal in tumors through the enhanced permeability and retention effect. Moreover, in contrast to non-biodegradable DCA, this DCA showed minimal long-term Gd 3+ retention in all organs and tissues because it could be degraded into small fragments. The significant capability of enhancing the MRI of metastases in the liver plus its excellent biodegradability made this DCA a promising CA for metastatic tumor imaging.

Real-time contrast ultrasound muscle perfusion imaging with intermediate-power imaging coupled with acoustically durable microbubbles.

PubMed

Seol, Sang-Hoon; Davidson, Brian P; Belcik, J Todd; Mott, Brian H; Goodman, Reid M; Ammi, Azzdine; Lindner, Jonathan R

2015-06-01

There is growing interest in limb contrast-enhanced ultrasound (CEU) perfusion imaging for the evaluation of peripheral artery disease. Because of low resting microvascular blood flow in skeletal muscle, signal enhancement during limb CEU is prohibitively low for real-time imaging. The aim of this study was to test the hypothesis that this obstacle can be overcome by intermediate- rather than low-power CEU when performed with an acoustically resilient microbubble agent. Viscoelastic properties of Definity and Sonazoid were assessed by measuring bulk modulus during incremental increases in ambient pressure to 200 mm Hg. Comparison of in vivo microbubble destruction and signal enhancement at a mechanical index (MI) of 0.1 to 0.4 was performed by sequential reduction in pulsing interval from 10 to 0.05 sec during limb CEU at 7 MHz in mice and 1.8 MHz in dogs. Destruction was also assessed by broadband signal generation during passive cavitation detection. Real-time CEU perfusion imaging with destruction-replenishment was then performed at 1.8 MHz in dogs using an MI of 0.1, 0.2, or 0.3. Sonazoid had a higher bulk modulus than Definity (66 ± 12 vs 29 ± 2 kPa, P = .02) and exhibited less inertial cavitation (destruction) at MIs ≥ 0.2. On in vivo CEU, maximal signal intensity increased incrementally with MI for both agents and was equivalent between agents except at an MI of 0.1 (60% and 85% lower for Sonazoid at 7 and 1.8 MHz, respectively, P < .05). However, on progressive shortening of the pulsing interval, Definity was nearly completely destroyed at MIs ≥ 0.2 at 1.8 and 7 MHz, whereas Sonazoid was destroyed only at 1.8 MHz at MIs ≥ 0.3. As a result, real-time CEU perfusion imaging demonstrated approximately fourfold greater enhancement for Sonazoid at an MI of 0.3 to 0.4. Robust signal enhancement during real-time CEU perfusion imaging of the limb is possible when using intermediate-power imaging coupled with a durable microbubble

Quantitative Differences Between the First and Second Injection of Contrast Agent in Contrast-Enhanced Ultrasonography of Feline Kidneys and Spleen.

PubMed

Stock, Emmelie; Vanderperren, Katrien; Haers, Hendrik; Duchateau, Luc; Hesta, Myriam; Saunders, Jimmy H

2017-02-01

Contrast-enhanced ultrasound is a valuable and safe technique for the evaluation of organ perfusion. Repeated injections of ultrasound contrast agent are often administered during the same imaging session. However, it remains unclear if quantitative differences are present between the consecutive microbubble injections. Therefore, the first and second injection of contrast agent for the left renal cortex, renal medulla and the splenic parenchyma in healthy cats were compared. A lower peak intensity and area under the curve were observed for the first injection of contrast agent in the feline kidney, both for the renal cortex and medulla, and spleen. Moreover, for the renal cortex, the time-intensity curve was steeper after the second injection. Findings from the present study demonstrate that a second injection of contrast agent provides stronger enhancement. The exact mechanism behind our findings remains unclear; however, saturation of the lung macrophages is believed to play an important role. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Vena Cava 3D Contrast-Enhanced MR Venography: A Pictorial Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin Jiang; Zhou Kangrong; Chen Zuwang

Three-dimensional contrast-enhanced magnetic resonance venography (CE MRV) is a sensitive and accurate method for diagnosing vena cava pathologies. The commonly used indirect approach involves a nondiluted gadolinium contrast agent injected into an upper limb vein or, occasionally, a pedal vein for assessment of the superior or inferior vena cava. In our studies, a coronal 3D fast multi-planar spoiled gradient-echo acquisition was used. A pre-contrast scan was obtained to ensure correct coverage of the region of interest. We initiated contrast-enhanced acquisition 15 sec after the start of contrast agent injection and performed the procedure twice. The image sets were obtained duringmore » two 20-30-sec breath hold, with a breathing rest of 5-6 sec, to obtain the first-pass and delayed arteriovenous phases. For patients with Budd-Chiari syndrome, a third acquisition coinciding with late venous phase was collected to visualize the hepatic veins, which was carried out by one additional acquisition after a 5-6-sec breathing time. This review describes the clinical application of 3D CE MRV in vena cava congenital anomalies, superior and inferior vena cava syndrome, Budd-Chiari syndrome, peripheral vein thrombosis extending to the vena cava, pre-operational evaluation in portosystemic shunting and post-surgical follow-up, and road-mapping for the placement and evaluation of complications of central venous devices.« less

Reproducibility of cerebrospinal venous blood flow and vessel anatomy with the use of phase contrast-vastly undersampled isotropic projection reconstruction and contrast-enhanced MRA.

PubMed

Schrauben, E M; Johnson, K M; Huston, J; Del Rio, A M; Reeder, S B; Field, A; Wieben, O

2014-05-01

The chronic cerebrospinal venous insufficiency hypothesis raises interest in cerebrospinal venous blood flow imaging, which is more complex and less established than in arteries. For accurate assessment of venous flow in chronic cerebrospinal venous insufficiency diagnosis and research, we must account for physiologic changes in flow patterns. This study examines day-to-day flow variability in cerebrospinal veins by use of 4D MR flow and contrast-enhanced MRA under typical, uncontrolled conditions in healthy individuals. Ten healthy volunteers were scanned in a test-retest fashion by use of a 4D flow MR imaging technique and contrast-enhanced MRA. Flow parameters obtained from phase contrast-vastly undersampled isotropic projection reconstruction and contrast-enhanced MRA scoring measurements in the head, neck, and chest veins were analyzed for internal consistency and interscan reproducibility. Internal consistency was satisfied at the torcular herophili, with an input-output difference of 2.2%. Percentages of variations in flow were 20.3%, internal jugular vein; 20.4%, azygos vein; 6.8%, transverse sinus; and 5.1%, common carotid artery. Retrograde flow was found in the lower internal jugular vein (4.8%) and azygos vein (7.2%). Contrast-enhanced MRA interscan κ values for the internal jugular vein (left: 0.474, right: 0.366) and azygos vein (-0.053) showed poor interscan agreement. Phase contrast-vastly undersampled isotropic projection reconstruction blood flow measurements are reliable and highly reproducible in intracranial veins and in the common carotid artery but not in veins of the neck (internal jugular vein) and chest (azygos vein) because of normal physiologic variation. Retrograde flow normally may be observed in the lower internal jugular vein and azygos vein. Low interrater agreement in contrast-enhanced MRA scans was observed. These findings have important implications for imaging diagnosis and experimental research of chronic cerebrospinal venous

Adaptive sigmoid function bihistogram equalization for image contrast enhancement

NASA Astrophysics Data System (ADS)

Arriaga-Garcia, Edgar F.; Sanchez-Yanez, Raul E.; Ruiz-Pinales, Jose; Garcia-Hernandez, Ma. de Guadalupe

2015-09-01

Contrast enhancement plays a key role in a wide range of applications including consumer electronic applications, such as video surveillance, digital cameras, and televisions. The main goal of contrast enhancement is to increase the quality of images. However, most state-of-the-art methods induce different types of distortion such as intensity shift, wash-out, noise, intensity burn-out, and intensity saturation. In addition, in consumer electronics, simple and fast methods are required in order to be implemented in real time. A bihistogram equalization method based on adaptive sigmoid functions is proposed. It consists of splitting the image histogram into two parts that are equalized independently by using adaptive sigmoid functions. In order to preserve the mean brightness of the input image, the parameter of the sigmoid functions is chosen to minimize the absolute mean brightness metric. Experiments on the Berkeley database have shown that the proposed method improves the quality of images and preserves their mean brightness. An application to improve the colorfulness of images is also presented.

Renal contrast-enhanced MR angiography: timing errors and accurate depiction of renal artery origins.

PubMed

Schmidt, Maria A; Morgan, Robert

2008-10-01

To investigate bolus timing artifacts that impair depiction of renal arteries at contrast material-enhanced magnetic resonance (MR) angiography and to determine the effect of contrast agent infusion rates on artifact generation. Renal contrast-enhanced MR angiography was simulated for a variety of infusion schemes, assuming both correct and incorrect timing between data acquisition and contrast agent injection. In addition, the ethics committee approved the retrospective evaluation of clinical breath-hold renal contrast-enhanced MR angiographic studies obtained with automated detection of contrast agent arrival. Twenty-two studies were evaluated for their ability to depict the origin of renal arteries in patent vessels and for any signs of timing errors. Simulations showed that a completely artifactual stenosis or an artifactual overestimation of an existing stenosis at the renal artery origin can be caused by timing errors of the order of 5 seconds in examinations performed with contrast agent infusion rates compatible with or higher than those of hand injections. Lower infusion rates make the studies more likely to accurately depict the origin of the renal arteries. In approximately one-third of all clinical examinations, different contrast agent uptake rates were detected on the left and right sides of the body, and thus allowed us to confirm that it is often impossible to optimize depiction of both renal arteries. In three renal arteries, a signal void was found at the origin in a patent vessel, and delayed contrast agent arrival was confirmed. Computer simulations and clinical examinations showed that timing errors impair the accurate depiction of renal artery origins. (c) RSNA, 2008.

Adrenal glands in hypovolemic shock: preservation of contrast enhancement at dynamic computed tomography.

PubMed

Ito, Katsuyoshi; Higashi, Hiroki; Kanki, Akihiko; Tamada, Tsutomu; Yamashita, Takenori; Yamamoto, Akira; Watanabe, Shigeru

2010-07-01

To evaluate contrast enhancement effects of the adrenal glands at dynamic computed tomography (CT) in adult severe trauma patients with hypovolemic shock in comparison with patients without hypovolemic shock. This study population included a total of 74 patients with (n = 24) and without (n = 50) blunt trauma and hypovolemic shock. Measurement of CT attenuation values of the adrenal gland and calculation of the enhancement washout percentages were performed. The mean +/- SD CT attenuation values of the adrenal glands in the arterial phase of dynamic CT in patients with hypovolemic shock (137.3 +/- 41.7 Hounsfield unit [HU]) were not significantly different (P = 0.16) from those in control subjects (127.3 +/- 19.6 HU). The mean CT attenuation values of the adrenal glands in the delayed phase of dynamic CT in patients with hypovolemic shock (82.0 +/- 14.7 HU) were also not significantly different (P = 0.89) from those in control subjects (82.4 +/- 10.0 HU). The mean percentage (35%) of enhancement washout of the adrenal glands in patients with hypovolemic shock was not significantly different (P = 0.81) from that (34%) in control subjects. Contrast enhancement effects of the adrenal glands at contrast-enhanced dynamic CT in patients with hypovolemic shock were similar to those in control subjects, indicating the preserved enhancement and perfusion of the adrenal gland rather than intense and persistent enhancement in patients with hypovolemic shock.

Histopathologic diversity of gastric cancers: Relationship between enhancement pattern on dynamic contrast-enhanced CT and histological type.

PubMed

Tsurumaru, Daisuke; Miyasaka, Mitsutoshi; Muraki, Toshio; Nishie, Akihiro; Asayama, Yoshiki; Oki, Eiji; Oda, Yoshinao; Honda, Hiroshi

2017-12-01

To evaluate the diagnostic value of contrast-enhanced computed tomography gastrography (CE-CTG) to predict the histological type of gastric cancer. We analyzed 47 consecutive patients with resectable advanced gastric cancer preoperatively evaluated by multiphasic dynamic contrast-enhanced CT. Two radiologists independently reviewed the CT images and they determined the peak enhancement phase, and then measured the CT attenuation value of the gastric lesion for each phase. The histological types of gastric cancers were assigned to three groups as differentiated-type, undifferentiated-type, and mixed-type. We compared the peak enhancement phase of the three types and compared the CT attenuation values in each phase. The peak enhancement was significantly different between the three types of gastric cancers for both readers (reader 1, p=0.001; reader 2, p=0.009); most of the undifferentiated types had peak enhancement in the delayed phase. The CT attenuation values of undifferentiated type were significantly higher than those of differentiated or mixed type in the delayed phase according to both readers (reader 1, p=0.002; reader 2, p=0.004). CE-CTG could provide helpful information in diagnosing the histological type of gastric cancers preoperatively. Copyright © 2017 Elsevier B.V. All rights reserved.

[Value of combined conventional and contrast enhanced sonography in the evaluation of hepatic disorders].

PubMed

Tranquart, F; Bleuzen, A; Kissel, A

2004-06-01

To assess the value of combined conventional and contrast-material enhanced sonography for the characterization of focal liver lesions. Simultaneous imaging with grey scale and contrast enhanced US was performed in 90 patients following Levovist injection (Schering, Berlin, Germany) using the "Agent Detection Imaging" method (ADI, Siemens-Acuson, Mountain View, USA). US scanning was performed at least 4 minutes after contrast injection with review of both grayscale and contrast enhanced modes. Results for detection and characterization of lesions were compared to the selected gold standard imaging modality (CT or MRI). Final diagnoses included: 20 normal examinations, 41 patients with metastases, 6 patients with hepatocellular carcinoma, 13 patients with hemangioma, 6 patients with other benign lesions, 4 patients with cysts and 6 patients with two types of lesions. Delayed phase contrast enhanced US allowed diagnosis of all lesions except for one metastasis and all hepatocellular carcinomas. While the diagnosis of hepatoma could not be confirmed, the features suggested a malignant etiology. For 7 patients with metastases, more lesions were detected at ADI (4.9 lesions) than at conventional US (1.1 lesion). For 3 patients, CT showed more lesions than ADI US (3.3 versus 1.6 lesions). The accuracy of ADI US for differentiating between benign and malignant lesions was 98.7% compared to 49.6% for conventional US (p<0.001). The total number of lesions detected at ADI US was higher (p<0.01) than at conventional US and not significantly different from that obtained by the gold standard reference methods. Complete characterization was achieved in 92.2% of cases with ADI US compared to 59.2% with conventional US (p<0.001). Contrast-material enhanced US combined with conventional US markedly improves the diagnostic accuracy of US in terms of lesion detection and characterization.

Dual-energy CT for detection of contrast enhancement or leakage within high-density haematomas in patients with intracranial haemorrhage.

PubMed

Watanabe, Yoshiyuki; Tsukabe, Akio; Kunitomi, Yuki; Nishizawa, Mitsuo; Arisawa, Atsuko; Tanaka, Hisashi; Yoshiya, Kazuhisa; Shimazu, Takeshi; Tomiyama, Noriyuki

2014-04-01

Our study aimed to elucidate the diagnostic performance of dual-energy CT (DECT) in the detection of contrast enhancement in intracranial haematomas (ICrH) with early phase dual-energy computed tomography angiography (CTA) and compare the results with those obtained by delayed CT enhancement. Thirty-six patients with ICrH were retrospectively included in this study. All patients had undergone single-energy non-contrast CT and contrast-enhanced dual-source DECT. DECT images were post-processed with commercial software, followed by obtaining iodine images and virtual non-contrast images and generating combined images that created the impression of 120-kVp images. Two neuroradiologists, blinded to the patients' data, reviewed two reading sessions: session A (non-contrast CT and combined CT) and session B (non-contrast CT, combined CT, and iodine images) for detection of contrast enhancement in the haematomas. Contrast leakage or enhancement was detected in 23 (57.5 %) out of 40 haemorrhagic lesions in 36 patients on delayed CT. Three enhanced lesions were depicted only in the DECT iodine images. The sensitivity, specificity, positive predictive value, and negative predictive value of session A were 82.6, 94.1, 95.0, and 80.0 %, respectively, and those of session B were 95.7, 94.1, 95.7, and 94.1 %, respectively. DECT emphasised the iodine enhancement and facilitated the detection of contrast enhancement or leakage.

Development of a Tumor Histologic-Specific, Nano-Encapsulated Contrast for Enhancing Magnetic Resonance Imaging of Prostate Cancer

DTIC Science & Technology

2008-04-01

Nano-Encapsulated Contrast for Enhancing Magnetic Resonance Imaging of Prostate Cancer PRINCIPAL INVESTIGATOR: Joel W. Slaton, M.D...2008 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Development of a Tumor Histologic-Specific, Nano-Encapsulated Contrast for Enhancing Magnetic...carry a contrast agent to human CaP cells growing in mice to enhance MR detection of cancer. Our work in the first year has focused on in vitro

Acute kidney injury after contrast-enhanced examination among elderly1

PubMed Central

Aoki, Beatriz Bonadio; Fram, Dayana; Taminato, Mônica; Batista, Ruth Ester Sayad; Belasco, Angélica; Barbosa, Dulce Aparecida

2014-01-01

OBJECTIVES: to assess renal function in elderly patients undergoing contrast-enhanced computed tomography and identify the preventive measures of acute kidney injury in the period before and after the examination. METHOD: longitudinal cohort study conducted at the Federal University of São Paulo Hospital, from March 2011 to March 2013. All hospitalized elderly, of both sexes, aged 60 years and above, who performed the examination, were included (n=93). We collected sociodemographic data, data related to the examination and to the care provided, and creatinine values prior and post exam. RESULTS: an alteration in renal function was observed in 51 patients (54%) with a statistically significant increase of creatinine values (p<0.04), and two patients (4.0%) required hemodialysis. CONCLUSION: There is an urgent need for protocols prior to and post contrast-enhanced examination in the elderly, and other studies to verify the prognosis of this population. PMID:25296148

Contrast enhancing solution for use in confocal microscopy

DOEpatents

Tannous, Zeina; Torres, Abel; Gonzalez, Salvador

2006-10-31

A method of optically detecting a tumor during surgery. The method includes imaging at least one test point defined on the tumor using a first optical imaging system to provide a first tumor image. The method further includes excising a first predetermined layer of the tumor for forming an in-vivo defect area. A predetermined contrast enhancing solution is disposed on the in-vivo defect area, which is adapted to interact with at least one cell anomaly, such as basal cell carcinoma, located on the in-vivo defect area for optically enhancing the cell anomaly. Thereafter the defect area can be optically imaged to provide a clear and bright representation of the cell anomaly to aid a surgeon while surgically removing the cell anomaly.

Quantifying long-term human impact in contrasting environments: Statistical analysis of modern and fossil pollen records

NASA Astrophysics Data System (ADS)

Broothaerts, Nils; López-Sáez, José Antonio; Verstraeten, Gert

2017-04-01

Reconstructing and quantifying human impact is an important step to understand human-environment interactions in the past. Quantitative measures of human impact on the landscape are needed to fully understand long-term influence of anthropogenic land cover changes on the global climate, ecosystems and geomorphic processes. Nevertheless, quantifying past human impact is not straightforward. Recently, multivariate statistical analysis of fossil pollen records have been proposed to characterize vegetation changes and to get insights in past human impact. Although statistical analysis of fossil pollen data can provide useful insights in anthropogenic driven vegetation changes, still it cannot be used as an absolute quantification of past human impact. To overcome this shortcoming, in this study fossil pollen records were included in a multivariate statistical analysis (cluster analysis and non-metric multidimensional scaling (NMDS)) together with modern pollen data and modern vegetation data. The information on the modern pollen and vegetation dataset can be used to get a better interpretation of the representativeness of the fossil pollen records, and can result in a full quantification of human impact in the past. This methodology was applied in two contrasting environments: SW Turkey and Central Spain. For each region, fossil pollen data from different study sites were integrated, together with modern pollen data and information on modern vegetation. In this way, arboreal cover, grazing pressure and agricultural activities in the past were reconstructed and quantified. The data from SW Turkey provides new integrated information on changing human impact through time in the Sagalassos territory, and shows that human impact was most intense during the Hellenistic and Roman Period (ca. 2200-1750 cal a BP) and decreased and changed in nature afterwards. The data from central Spain shows for several sites that arboreal cover decreases bellow 5% from the Feudal period

Diagnostic Accuracy of Dynamic Contrast Enhanced Magnetic Resonance Imaging in Characterizing Lung Masses

PubMed Central

Inan, Nagihan; Arslan, Arzu; Donmez, Muhammed; Sarisoy, Hasan Tahsin

2016-01-01

Background Imaging plays a critical role not only in the detection, but also in the characterization of lung masses as benign or malignant. Objectives To determine the diagnostic accuracy of dynamic magnetic resonance imaging (MRI) in the differential diagnosis of benign and malignant lung masses. Patients and Methods Ninety-four masses were included in this prospective study. Five dynamic series of T1-weighted spoiled gradient echo (FFE) images were obtained, followed by a T1-weighted FFE sequence in the late phase (5th minutes). Contrast enhancement patterns in the early (25th second) and late (5th minute) phase images were evaluated. For the quantitative evaluation, signal intensity (SI)-time curves were obtained and the maximum relative enhancement, wash-in rate, and time-to-peak enhancement of masses in both groups were calculated. Results The early phase contrast enhancement patterns were homogeneous in 78.2% of the benign masses, while heterogeneous in 74.4% of the malignant tumors. On the late phase images, 70.8% of the benign masses showed homogeneous enhancement, while most of the malignant masses showed heterogeneous enhancement (82.4%). During the first pass, the maximum relative enhancement and wash-in rate values of malignant masses were significantly higher than those of the benign masses (P = 0.03 and 0.04, respectively). The cutoff value at 15% yielded a sensitivity of 85.4%, specificity of 61.2%, and positive predictive value of 68.7% for the maximum relative enhancement. Conclusion Contrast enhancement patterns and SI-time curve analysis of MRI are helpful in the differential diagnosis of benign and malignant lung masses. PMID:27703654

A Three-Stage Enhanced Reactive Power and Voltage Optimization Method for High Penetration of Solar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ke, Xinda; Huang, Renke; Vallem, Mallikarjuna R.

This paper presents a three-stage enhanced volt/var optimization method to stabilize voltage fluctuations in transmission networks by optimizing the usage of reactive power control devices. In contrast with existing volt/var optimization algorithms, the proposed method optimizes the voltage profiles of the system, while keeping the voltage and real power output of the generators as close to the original scheduling values as possible. This allows the method to accommodate realistic power system operation and market scenarios, in which the original generation dispatch schedule will not be affected. The proposed method was tested and validated on a modified IEEE 118-bus system withmore » photovoltaic data.« less

Effect of contrast enhancement prior to iteration procedure on image correction for soft x-ray projection microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jamsranjav, Erdenetogtokh, E-mail: ja.erdenetogtokh@gmail.com; Shiina, Tatsuo, E-mail: shiina@faculity.chiba-u.jp; Kuge, Kenichi

2016-01-28

Soft X-ray microscopy is well recognized as a powerful tool of high-resolution imaging for hydrated biological specimens. Projection type of it has characteristics of easy zooming function, simple optical layout and so on. However the image is blurred by the diffraction of X-rays, leading the spatial resolution to be worse. In this study, the blurred images have been corrected by an iteration procedure, i.e., Fresnel and inverse Fresnel transformations repeated. This method was confirmed by earlier studies to be effective. Nevertheless it was not enough to some images showing too low contrast, especially at high magnification. In the present study,more » we tried a contrast enhancement method to make the diffraction fringes clearer prior to the iteration procedure. The method was effective to improve the images which were not successful by iteration procedure only.« less

Dynamic Contrast-Enhanced MRI of Cervical Cancers: Temporal Percentile Screening of Contrast Enhancement Identifies Parameters for Prediction of Chemoradioresistance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersen, Erlend K.F.; Hole, Knut Hakon; Lund, Kjersti V.

Purpose: To systematically screen the tumor contrast enhancement of locally advanced cervical cancers to assess the prognostic value of two descriptive parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Methods and Materials: This study included a prospectively collected cohort of 81 patients who underwent DCE-MRI with gadopentetate dimeglumine before chemoradiotherapy. The following descriptive DCE-MRI parameters were extracted voxel by voxel and presented as histograms for each time point in the dynamic series: normalized relative signal increase (nRSI) and normalized area under the curve (nAUC). The first to 100th percentiles of the histograms were included in a log-rank survival test,more » resulting in p value and relative risk maps of all percentile-time intervals for each DCE-MRI parameter. The maps were used to evaluate the robustness of the individual percentile-time pairs and to construct prognostic parameters. Clinical endpoints were locoregional control and progression-free survival. The study was approved by the institutional ethics committee. Results: The p value maps of nRSI and nAUC showed a large continuous region of percentile-time pairs that were significantly associated with locoregional control (p < 0.05). These parameters had prognostic impact independent of tumor stage, volume, and lymph node status on multivariate analysis. Only a small percentile-time interval of nRSI was associated with progression-free survival. Conclusions: The percentile-time screening identified DCE-MRI parameters that predict long-term locoregional control after chemoradiotherapy of cervical cancer.« less

Can contrast-enhanced ultrasonography improve Zone III REBOA placement for prehospital care?

PubMed

Chaudery, Muzzafer; Clark, James; Morrison, Jonathan J; Wilson, Mark H; Bew, Duncan; Darzi, Ara

2016-01-01

Torso hemorrhage is the primary cause of potentially preventable mortality in trauma. Resuscitative endovascular balloon occlusion of the aorta (REBOA) has been advocated as an adjunct to bridge patients to definitive hemorrhage control. The primary aim of this study was to assess whether contrast-enhanced ultrasonography can improve the accuracy of REBOA placement in the infrarenal aorta (Zone III). A fluoroscopy-free "enhanced" Zone III REBOA technique was developed using a porcine cadaver model. A "standard" over-the-wire Seldinger technique was used, which was enhanced with the addition of a microbubble contrast medium to inflate the balloon, observed with ultrasonography. Following this, attending- and resident-level physicians were randomized into two groups. They were taught either the enhanced with ultrasonography guidance (Group A) or the standard measuring length of catheter insertion (Group B) technique as part of a human cadaver trauma skills course. Outcomes assessed included time (seconds) from insertion to inflation, accuracy, and missed targets. All results were benchmarked against three endovascular experts. There were 20 participants who performed REBOA with Group A (51 [31]) being significantly faster than Group B (90 [63]) (p = 0.003) and more accurate (p = 0.023) with no missed targets. Group B had five missed targets, the most common error being inflation within Zone II. For Zone III REBOA, contrast-enhanced ultrasonography technique is faster and more accurate than the standard technique. This may have value in time-critical and austere environments. Clinical studies are now required to evaluate this approach further.

An in vivo, MRI-integrated real-time model of active contrast extravasation in acute intracerebral hemorrhage.

PubMed

Aviv, R I; Huynh, T; Huang, Y; Ramsay, D; Van Slyke, P; Dumont, D; Asmah, P; Alkins, R; Liu, R; Hynynen, K

2014-09-01

The "spot sign" or contrast extravasation is strongly associated with hematoma formation and growth. An animal model of contrast extravasation is important to test existing and novel therapeutic interventions to inform present and future clinical studies. The purpose of this study was to create an animal model of contrast extravasation in acute intracerebral hemorrhage. Twenty-eight hemispheres of Yorkshire male swine were insonated with an MR imaging-guided focused sonography system following lipid microsphere infusion and mean arterial pressure elevation. The rate of contrast leakage was quantified by using dynamic contrast-enhanced MR imaging and was classified as contrast extravasation or postcontrast leakage by using postcontrast T1. Hematoma volume was measured on gradient recalled-echo MR imaging performed 2 hours postprocedure. Following this procedure, sacrificed brain was subjected to histopathologic examination. Power level, burst length, and blood pressure elevation were correlated with leakage rate, hematoma size, and vessel abnormality extent. Median (intracerebral hemorrhage) contrast extravasation leakage was higher than postcontrast leakage (11.3; 6.3-23.2 versus 2.4; 1.1-3.1 mL/min/100 g; P<.001). Increasing burst length, gradient recalled-echo hematoma (ρ=0.54; 95% CI, 0.2-0.8; P=.007), and permeability were correlated (ρ=0.55; 95% CI, 0.1-0.8; P=.02). Median permeability (P=.02), gradient recalled-echo hematoma (P=.02), and dynamic contrast-enhanced volumes (P=.02) were greater at 1000 ms than at 10 ms. Within each burst-length subgroup, incremental contrast leakage was seen with mean arterial pressure elevation (ρ=0.2-0.8). We describe a novel MR imaging-integrated real-time swine intracerebral hemorrhage model of acute hematoma growth and contrast extravasation. © 2014 by American Journal of Neuroradiology.

Quantitative contrast-enhanced ultrasound imaging: a review of sources of variability

PubMed Central

Tang, M.-X.; Mulvana, H.; Gauthier, T.; Lim, A. K. P.; Cosgrove, D. O.; Eckersley, R. J.; Stride, E.

2011-01-01

Ultrasound provides a valuable tool for medical diagnosis offering real-time imaging with excellent spatial resolution and low cost. The advent of microbubble contrast agents has provided the additional ability to obtain essential quantitative information relating to tissue vascularity, tissue perfusion and even endothelial wall function. This technique has shown great promise for diagnosis and monitoring in a wide range of clinical conditions such as cardiovascular diseases and cancer, with considerable potential benefits in terms of patient care. A key challenge of this technique, however, is the existence of significant variations in the imaging results, and the lack of understanding regarding their origin. The aim of this paper is to review the potential sources of variability in the quantification of tissue perfusion based on microbubble contrast-enhanced ultrasound images. These are divided into the following three categories: (i) factors relating to the scanner setting, which include transmission power, transmission focal depth, dynamic range, signal gain and transmission frequency, (ii) factors relating to the patient, which include body physical differences, physiological interaction of body with bubbles, propagation and attenuation through tissue, and tissue motion, and (iii) factors relating to the microbubbles, which include the type of bubbles and their stability, preparation and injection and dosage. It has been shown that the factors in all the three categories can significantly affect the imaging results and contribute to the variations observed. How these factors influence quantitative imaging is explained and possible methods for reducing such variations are discussed. PMID:22866229

Contrast-enhanced spectral mammography based on a photon-counting detector: quantitative accuracy and radiation dose

NASA Astrophysics Data System (ADS)

Lee, Seungwan; Kang, Sooncheol; Eom, Jisoo

2017-03-01

Contrast-enhanced mammography has been used to demonstrate functional information about a breast tumor by injecting contrast agents. However, a conventional technique with a single exposure degrades the efficiency of tumor detection due to structure overlapping. Dual-energy techniques with energy-integrating detectors (EIDs) also cause an increase of radiation dose and an inaccuracy of material decomposition due to the limitations of EIDs. On the other hands, spectral mammography with photon-counting detectors (PCDs) is able to resolve the issues induced by the conventional technique and EIDs using their energy-discrimination capabilities. In this study, the contrast-enhanced spectral mammography based on a PCD was implemented by using a polychromatic dual-energy model, and the proposed technique was compared with the dual-energy technique with an EID in terms of quantitative accuracy and radiation dose. The results showed that the proposed technique improved the quantitative accuracy as well as reduced radiation dose comparing to the dual-energy technique with an EID. The quantitative accuracy of the contrast-enhanced spectral mammography based on a PCD was slightly improved as a function of radiation dose. Therefore, the contrast-enhanced spectral mammography based on a PCD is able to provide useful information for detecting breast tumors and improving diagnostic accuracy.

Contrast-enhanced time-resolved MRA for follow-up of intracranial aneurysms treated with the pipeline embolization device.

PubMed

Boddu, S R; Tong, F C; Dehkharghani, S; Dion, J E; Saindane, A M

2014-01-01

Endovascular reconstruction and flow diversion by using the Pipeline Embolization Device is an effective treatment for complex cerebral aneurysms. Accurate noninvasive alternatives to DSA for follow-up after Pipeline Embolization Device treatment are desirable. This study evaluated the accuracy of contrast-enhanced time-resolved MRA for this purpose, hypothesizing that contrast-enhanced time-resolved MRA will be comparable with DSA and superior to 3D-TOF MRA. During a 24-month period, 37 Pipeline Embolization Device-treated intracranial aneurysms in 26 patients underwent initial follow-up by using 3D-TOF MRA, contrast-enhanced time-resolved MRA, and DSA. MRA was performed on a 1.5T unit by using 3D-TOF and time-resolved imaging of contrast kinetics. All patients underwent DSA a median of 0 days (range, 0-68) after MRA. Studies were evaluated for aneurysm occlusion, quality of visualization of the reconstructed artery, and measurable luminal diameter of the Pipeline Embolization Device, with DSA used as the reference standard. The sensitivity, specificity, and positive and negative predictive values of contrast-enhanced time-resolved MRA relative to DSA for posttreatment aneurysm occlusion were 96%, 85%, 92%, and 92%. Contrast-enhanced time-resolved MRA demonstrated superior quality of visualization (P = .0001) and a higher measurable luminal diameter (P = .0001) of the reconstructed artery compared with 3D-TOF MRA but no significant difference compared with DSA. Contrast-enhanced time-resolved MRA underestimated the luminal diameter of the reconstructed artery by 0.965 ± 0.497 mm (27% ± 13%) relative to DSA. Contrast-enhanced time-resolved MRA is a reliable noninvasive method for monitoring intracranial aneurysms following flow diversion and vessel reconstruction by using the Pipeline Embolization Device. © 2014 by American Journal of Neuroradiology.

Tumor characterization in small animals using magnetic resonance-guided dynamic contrast enhanced diffuse optical tomography

NASA Astrophysics Data System (ADS)

Lin, Yuting; Thayer, Dave; Nalcioglu, Orhan; Gulsen, Gultekin

2011-10-01

We present a magnetic resonance (MR)-guided near-infrared dynamic contrast enhanced diffuse optical tomography (DCE-DOT) system for characterization of tumors using an optical contrast agent (ICG) and a MR contrast agent [Gd-diethylenetriaminepentaacetic acid (DTPA)] in a rat model. Both ICG and Gd-DTPA are injected and monitored simultaneously using a combined MRI-DOT system, resulting in accurate co-registration between two imaging modalities. Fisher rats bearing R3230 breast tumor are imaged using this hybrid system. For the first time, enhancement kinetics of the exogenous contrast ICG is recovered from the DCE-DOT data using MR anatomical a priori information. As tumors grow, they undergo necrosis and the tissue transforms from viable to necrotic. The results show that the physiological changes between viable and necrotic tissue can be differentiated more accurately based on the ICG enhancement kinetics when MR anatomical information is utilized.

Combined Dynamic Contrast Enhanced Liver MRI and MRA Using Interleaved Variable Density Sampling

PubMed Central

Rahimi, Mahdi Salmani; Korosec, Frank R.; Wang, Kang; Holmes, James H.; Motosugi, Utaroh; Bannas, Peter; Reeder, Scott B.

2014-01-01

Purpose To develop and evaluate a method for volumetric contrast-enhanced MR imaging of the liver, with high spatial and temporal resolutions, for combined dynamic imaging and MR angiography using a single injection of contrast. Methods An interleaved variable density (IVD) undersampling pattern was implemented in combination with a real-time-triggered, time-resolved, dual-echo 3D spoiled gradient echo sequence. Parallel imaging autocalibration lines were acquired only once during the first time-frame. Imaging was performed in ten subjects with focal nodular hyperplasia (FNH) and compared with their clinical MRI. The angiographic phase of the proposed method was compared to a dedicated MR angiogram acquired during a second injection of contrast. Results A total of 21 FNH, 3 cavernous hemangiomas, and 109 arterial segments were visualized in 10 subjects. The temporally-resolved images depicted the characteristic arterial enhancement pattern of the lesions with a 4 s update rate. Images were graded as having significantly higher quality compared to the clinical MRI. Angiograms produced from the IVD method provided non-inferior diagnostic assessment compared to the dedicated MRA. Conclusion Using an undersampled IVD imaging method, we have demonstrated the feasibility of obtaining high spatial and temporal resolution dynamic contrast-enhanced imaging and simultaneous MRA of the liver. PMID:24639130

Optimal exposure techniques for iodinated contrast enhanced breast CT

NASA Astrophysics Data System (ADS)

Glick, Stephen J.; Makeev, Andrey

2016-03-01

Screening for breast cancer using mammography has been very successful in the effort to reduce breast cancer mortality, and its use has largely resulted in the 30% reduction in breast cancer mortality observed since 1990 [1]. However, diagnostic mammography remains an area of breast imaging that is in great need for improvement. One imaging modality proposed for improving the accuracy of diagnostic workup is iodinated contrast-enhanced breast CT [2]. In this study, a mathematical framework is used to evaluate optimal exposure techniques for contrast-enhanced breast CT. The ideal observer signal-to-noise ratio (i.e., d') figure-of-merit is used to provide a task performance based assessment of optimal acquisition parameters under the assumptions of a linear, shift-invariant imaging system. A parallel-cascade model was used to estimate signal and noise propagation through the detector, and a realistic lesion model with iodine uptake was embedded into a structured breast background. Ideal observer performance was investigated across kVp settings, filter materials, and filter thickness. Results indicated many kVp spectra/filter combinations can improve performance over currently used x-ray spectra.

Practical application of contrast-enhanced magnetic resonance mammography [CE-MRM] by an algorithm combining morphological and enhancement patterns.

PubMed

Potente, Giuseppe; Messineo, Daniela; Maggi, Claudia; Savelli, Sara

2009-03-01

The purpose of this article is to report our practical utilization of dynamic contrast-enhanced magnetic resonance mammography [DCE-MRM] in the diagnosis of breast lesions. In many European centers, was preferred a high-temporal acquisition of both breasts simultaneously in a large FOV. We preferred to scan single breasts, with the aim to combine the analysis of the contrast intake and washout with the morphological evaluation of breast lesions. We followed an interpretation model, based upon a diagnostic algorithm, which combined contrast enhancement with morphological evaluation, in order to increase our confidence in diagnosis. DCE-MRM with our diagnostic algorithm has identified 179 malignant and 41 benign lesions; final outcome has identified 178 malignant and 42 benign lesions, 3 false positives and 2 false negatives. Sensitivity of CE-MRM was 98.3%; specificity, 95.1%; positive predictive value, 98.9%; negative predictive value, 92.8% and accuracy, 97.7%.

Using Dynamic Contrast Enhanced MRI to Quantitatively Characterize Maternal Vascular Organization in the Primate Placenta

PubMed Central

Frias, A.E.; Schabel, M.C.; Roberts, V.H.J.; Tudorica, A.; Grigsby, P.L.; Oh, K.Y.; Kroenke, C. D.

2015-01-01

Purpose The maternal microvasculature of the primate placenta is organized into 10-20 perfusion domains that are functionally optimized to facilitate nutrient exchange to support fetal growth. This study describes a dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) method for identifying vascular domains, and quantifying maternal blood flow in them. Methods A rhesus macaque on the 133rd day of pregnancy (G133, term=165 days) underwent Doppler ultrasound (US) procedures, DCE-MRI, and Cesarean-section delivery. Serial T1-weighted images acquired throughout intravenous injection of a contrast reagent (CR) bolus were analyzed to obtain CR arrival time maps of the placenta. Results Watershed segmentation of the arrival time map identified 16 perfusion domains. The number and location of these domains corresponded to anatomical cotyledonary units observed following delivery. Analysis of the CR wave front through each perfusion domain enabled determination of volumetric flow, which ranged from 9.03 to 44.9 mL/sec (25.2 ± 10.3 mL/sec). These estimates are supported by Doppler US results. Conclusions The DCE-MRI analysis described here provides quantitative estimates of the number of maternal perfusion domains in a primate placenta, and estimates flow within each domain. Anticipated extensions of this technique are to the study placental function in nonhuman primate models of obstetric complications. PMID:24753177

Dual-frequency transducer with a wideband PVDF receiver for contrast-enhanced, adjustable harmonic imaging

NASA Astrophysics Data System (ADS)

Kim, Jinwook; Lindsey, Brooks D.; Li, Sibo; Dayton, Paul A.; Jiang, Xiaoning

2017-04-01

Acoustic angiography is a contrast-enhanced, superharmonic microvascular imaging method. It has shown the capability of high-resolution and high-contrast-to-tissue-ratio (CTR) imaging for vascular structure near tumor. Dual-frequency ultrasound transducers and arrays are usually used for this new imaging technique. Stacked-type dual-frequency transducers have been developed for this vascular imaging method by exciting injected microbubble contrast agent (MCA) in the vessels with low-frequency (1-5 MHz), moderate power ultrasound burst waves and receiving the superharmonic responses from MCA by a high-frequency receiver (>10 MHz). The main challenge of the conventional dual-frequency transducers is a limited penetration depth (<25 mm) due to the insufficient receiving sensitivity for highfrequency harmonic signal detection. A receiver with a high receiving sensitivity spanning a wide superharmonic frequency range (3rd to 6th) enables selectable bubble harmonic detection considering the required penetration depth. Here, we develop a new dual-frequency transducer composed of a 2 MHz 1-3 composite transmitter and a polyvinylidene fluoride (PVDF) receiver with a receiving frequency range of 4-12 MHz for adjustable harmonic imaging. The developed transducer was tested for harmonic responses from a microbubble-injected vessel-mimicking tube positioned 45 mm away. Despite the long imaging distance (45 mm), the prototype transducer detected clear harmonic response with the contrast-to-noise ratio of 6-20 dB and the -6 dB axial resolution of 200-350 μm for imaging a 200 um-diameter cellulose tube filled with microbubbles.

Automatic image equalization and contrast enhancement using Gaussian mixture modeling.

PubMed

Celik, Turgay; Tjahjadi, Tardi

2012-01-01

In this paper, we propose an adaptive image equalization algorithm that automatically enhances the contrast in an input image. The algorithm uses the Gaussian mixture model to model the image gray-level distribution, and the intersection points of the Gaussian components in the model are used to partition the dynamic range of the image into input gray-level intervals. The contrast equalized image is generated by transforming the pixels' gray levels in each input interval to the appropriate output gray-level interval according to the dominant Gaussian component and the cumulative distribution function of the input interval. To take account of the hypothesis that homogeneous regions in the image represent homogeneous silences (or set of Gaussian components) in the image histogram, the Gaussian components with small variances are weighted with smaller values than the Gaussian components with larger variances, and the gray-level distribution is also used to weight the components in the mapping of the input interval to the output interval. Experimental results show that the proposed algorithm produces better or comparable enhanced images than several state-of-the-art algorithms. Unlike the other algorithms, the proposed algorithm is free of parameter setting for a given dynamic range of the enhanced image and can be applied to a wide range of image types.

Effect of contrast media on megavoltage photon beam dosimetry.

PubMed

Rankine, Ashley W; Lanzon, Peter J; Spry, Nigel A

2008-01-01

The purpose of this study was to quantify changes in photon beam dosimetry caused by using contrast media during computed tomography (CT) simulation and determine if the resulting changes are clinically significant. The effect of contrast on dosimetry was first examined for a single 6-MV photon beam incident on a plane phantom with a structure of varying electron densities (rho(e)) and thickness. Patient studies were then undertaken in which CT data sets were collected with and without contrast for 6 typical patients. Three patients received IV contrast (Optiray-240) only and 3 received IV plus oral (Gastrograffin) contrast. Each patient was planned using conformal multifield techniques in accordance with the department standards. Two methods were used to compare the effect of contrast on dosimetry for each patient. The phantom analysis showed that the change in dose at the isocenter for a single 10 x 10 cm2 6-MV photon beam traversing 10 cm of a contrast-enhanced structure with rho(e) 1.22 was 7.0% (1.22 was the highest average rho(e) observed in the patient data). As a result of using contrast, increases in rho(e) were observed in structures for the 6 patients studied. Consequently, when using contrast-enhanced CT data for multifield planning, increases in dose at the isocenter and in critical structures were observed up to 2.1% and 2.5%, respectively. Planning on contrast-enhanced CT images may result in an increase in dose of up to 2.1% at the isocenter, which would generally be regarded as clinically insignificant. If, however, a critical organ is in close proximity to the planning target volume (PTV) and is planned to receive its maximum allowable dose, planning on contrast-enhanced CT images may result in that organ receiving dose beyond the recommended tolerance. In these instances, pre-contrast CT data should be used for dosimetry.

Gadolinium-free MR in coarctation-can contrast-enhanced MR angiography be replaced?

PubMed

Kalmar, Peter I; Koestenberger, Martin; Marterer, Robert; Tschauner, Sebastian; Sorantin, Erich

2016-01-01

To determine the difference in vessel measurements, signal-to-noise ratio (SNR), and voxel size between contrast-enhanced and noncontrast magnetic resonance techniques in patients with coarctation of the aorta (CoA). In 39 patients, vessel size, SNR, and voxel size were compared in cine magnetic resonance imaging (MRI), gadolinium-free magnetic resonance angiography (Gd-free MRA), and contrast-enhanced MRA (ce-MRA). There was no significant difference in measurement and SNR, but there was a significant difference in voxel size (P<.001). Our results show that, in CoA patients, monitoring of vessel size using cine MRI and Gd-free MRA is equivalent to ce-MRA while being less invasive. Copyright © 2016 Elsevier Inc. All rights reserved.

Dynamic contrast-enhanced MRI evaluation of cerebral cavernous malformations.

PubMed

Hart, Blaine L; Taheri, Saeid; Rosenberg, Gary A; Morrison, Leslie A

2013-10-01

The aim of this study is to quantitatively evaluate the behavior of CNS cavernous malformations (CCMs) using a dynamic contrast-enhanced MRI (DCEMRI) technique sensitive for slow transfer rates of gadolinium. The prospective study was approved by the institutional review board and was HIPPA compliant. Written informed consent was obtained from 14 subjects with familial CCMs (4 men and 10 women, ages 22-76 years, mean 48.1 years). Following routine anatomic MRI of the brain, DCEMRI was performed for six slices, using T1 mapping with partial inversion recovery (TAPIR) to calculate T1 values, following administration of 0.025 mmol/kg gadolinium DTPA. The transfer rate (Ki) was calculated using the Patlak model, and Ki within CCMs was compared to normal-appearing white matter as well as to 17 normal control subjects previously studied. All subjects had typical MRI appearance of CCMs. Thirty-nine CCMs were studied using DCEMRI. Ki was low or normal in 12 lesions and elevated from 1.4 to 12 times higher than background in the remaining 27 lesions. Ki ranged from 2.1E-6 to 9.63E-4 min(-1), mean 3.55E-4. Normal-appearing white matter in the CCM patients had a mean Ki of 1.57E-4, not statistically different from mean WM Ki of 1.47E-4 in controls. TAPIR-based DCEMRI technique permits quantifiable assessment of CCMs in vivo and reveals considerable differences not seen with conventional MRI. Potential applications include correlation with biologic behavior such as lesion growth or hemorrage, and measurement of drug effects.

Dynamic Contrast-Enhanced MRI Evaluation of Cerebral Cavernous Malformations

PubMed Central

Hart, B. L.; Taheri, S.; Rosenberg, G. A.; Morrison, L. A.

2013-01-01

The aim of this study is to quantitatively evaluate the behavior of CNS cavernous malformations (CCMs) using a dynamic contrast-enhanced MRI (DCEMRI) technique sensitive for slow transfer rates of gadolinium. The prospective study was approved by the institutional review board and was HIPPA compliant. Written informed consent was obtained from 14 subjects with familial CCMs (4 men and 10 women, ages 22–76 years, mean 48.1 years). Following routine anatomic MRI of the brain, DCEMRI was performed for six slices, using T1 mapping with partial inversion recovery (TAPIR) to calculate T1 values, following administration of 0.025 mmol/kg gadolinium DTPA. The transfer rate (Ki) was calculated using the Patlak model, and Ki within CCMs was compared to normal-appearing white matter as well as to 17 normal control subjects previously studied. All subjects had typical MRI appearance of CCMs. Thirty-nine CCMs were studied using DCEMRI. Ki was low or normal in 12 lesions and elevated from 1.4 to 12 times higher than background in the remaining 27 lesions. Ki ranged from 2.1E–6 to 9.63E–4 min−1, mean 3.55E–4. Normal-appearing white matter in the CCM patients had a mean Ki of 1.57E–4, not statistically different from mean WM Ki of 1.47E–4 in controls. TAPIR-based DCEMRI technique permits quantifiable assessment of CCMs in vivo and reveals considerable differences not seen with conventional MRI. Potential applications include correlation with biologic behavior such as lesion growth or hemorrage, and measurement of drug effects. PMID:24323376

Spectral contrast-enhanced optical coherence tomography for improved detection of tumor microvasculature and functional imaging of lymphatic drainage

NASA Astrophysics Data System (ADS)

SoRelle, Elliott D.; Liba, Orly; Sen, Debasish; de la Zerda, Adam

2017-03-01

Optical Coherence Tomography (OCT) is well-suited to study in vivo dynamics of blood circulation and lymphatic flow because of the technique's combination of rapid image acquisition, micron spatial resolution, and penetration depth in turbid tissues. However, OCT has been historically constrained by a dearth of contrast agents that are readily distinguished from the strong scattering intrinsic to biological tissues. In this study, we demonstrate large gold nanorods (LGNRs) as optimized contrast agents for OCT. LGNRs produce 32-fold greater backscattering than GNRs previously tested for contrast-enhanced OCT. Furthermore, LGNRs exhibit 110-fold stronger spectral signal than conventional GNRs when coupled with custom spectral detection algorithms. This signal enhancement enables picomolar OCT detection sensitivity in vivo and single-particle detection against optically-clear backgrounds. Moreover, the ability to synthesize LGNRs with tunable spectral peaks provides a viable platform for multiplexed imaging studies. To explore the advantages of LGNRs as OCT contrast agents, we implemented them for noninvasive 3D imaging of tumor blood supply and active lymphatic drainage in mice. Spectral detection of LGNRs enabled 100% improvement in imaging depth for detecting microvasculature (vessels 20 μm in diameter) in U87MG glioblastoma xenografts in mice pinnae. We also demonstrated our approach's ability to map the spatial dependence of lymph drainage and flow directionality within lymphatic capillaries. Using LGNRs with distinct spectra, we further identified the functional states of individual lymphatic valves in vivo. Thus, this approach provides a powerful new platform for functional imaging that may be extended for future molecular imaging studies with OCT.

FEASIBILITY AND SAFETY OF CONTRAST-ENHANCED ULTRASOUND IN THE DISTAL LIMB OF SIX HORSES.

PubMed

Seiler, Gabriela S; Campbell, Nigel; Nixon, Britton; Tsuruta, James K; Dayton, Paul A; Jennings, Samuel; Redding, W Rich; Lustgarten, Meghann

2016-05-01

Vascular alterations play important roles in many orthopedic diseases such as osteoarthritis, tendonitis, and synovitis in both human and equine athletes. Understanding these alterations could enhance diagnosis, prognosis, and treatment. Contrast-enhanced ultrasound (CEUS) could be a valuable method for evaluation of blood flow and perfusion of these processes in the equine distal limb, however no reports were found describing feasibility or safety of the technique. The goal of this prospective, experimental study was to describe the feasibility and safety of distal limb CEUS in a sample of six horses. For each horse, CEUS of the distal limb was performed after intravenous injections of 5 and 10 ml, as well as intra-arterial injections of 0.5 and 1 ml contrast medium. Vital parameters were monitored and CEUS images were assessed qualitatively and quantitatively for degree of contrast enhancement. None of the horses had clinically significant changes in their vital parameters after contrast medium injection. One horse had a transient increase in respiratory rate, and several horses had mild increases of systolic blood pressure of short duration after intravenous, but not after intra-arterial injections. Intra-arterial injection was possible in all horses and resulted in significantly improved contrast enhancement both quantitatively (P = 0.027) and qualitatively (P = 0.019). Findings from this study indicated that CEUS is a feasible and safe diagnostic test for evaluation of the equine distal limb. Future studies are needed to assess the clinical utility of this test for horses with musculoskeletal diseases. © 2016 American College of Veterinary Radiology.

Contrast Enhancement of the Right Ventricle during Coronary CT Angiography--Is It Necessary?

PubMed

Kok, Madeleine; Kietselaer, Bas L J H; Mihl, Casper; Altintas, Sibel; Nijssen, Estelle C; Wildberger, Joachim E; Das, Marco

2015-01-01

It is unclear if prolonged contrast media injection, to improve right ventricular visualization during coronary CT angiography, leads to increased detection of right ventricle pathology. The purpose of this study was to evaluate right ventricle enhancement and subsequent detection of right ventricle disease during coronary CT angiography. 472 consecutive patients referred for screening coronary CT angiography were retrospectively evaluated. Every patient underwent multidetector-row CT of the coronary arteries: 128x 0.6mm coll., 100-120kV, rot. time 0.28s, ref. mAs 350 and received an individualized (P3T) contrast bolus injection of iodinated contrast medium (300 mgI/ml). Patient data were analyzed to assess right ventricle enhancement (HU) and right ventricle pathology. Image quality was defined good when right ventricle enhancement >200HU, moderate when 140-200HU and poor when <140HU. Good image quality was found in 372 patients, moderate in 80 patients and poor in 20 patients. Mean enhancement of the right ventricle cavity was 268HU±102. Patients received an average bolus of 108±24 ml at an average peak flow rate of 6.1±2.2 ml/s. In only three out of 472 patients (0.63%) pathology of the right ventricle was found (dilatation) No other right ventricle pathology was detected. Right ventricle pathology was detected in three out of 472 patients; the dilatation observed in these three cases may have been picked up even without dedicated enhancement of the right ventricle. Based on our findings, right ventricle enhancement can be omitted during screening coronary CT angiography.

Contrast-enhanced dual-energy digital subtraction mammography: optimization of the beam energy

NASA Astrophysics Data System (ADS)

Kwan, Alexander L. C.; Boone, John M.; Le-Petross, Huong; Lindfors, Karen K.; Seibert, J. A.; Lewin, John M.

2005-04-01

The implementation of contrast-enhanced dual-energy digital subtraction mammography may lead to better identification of breast tumors, and thus provide a lower cost and more widely available alternative to breast MRI. This technique involves the acquisition of low- and high-energy images after the IV administration of iodinated contrast agent. In this study, the effect of the beam energy (kVp) was examined using the CNR2/dose metric, where CNR is the contrast-to-noise ratio and dose implies the mean glandular dose. The mean glandular dose was calculated using parameterized normalized glandular dose coefficients (DgN), which allowed the computation of the mean glandular dose for the modeled spectra considered in this study, coupled with incident kerma measurements. Optimization studies were performed using a dedicated cone-beam breast CT scanner designed and fabricated in our laboratory, with the system operating in stationary imaging mode. A flat tissue-equivalent phantom (7.5 cm in thickness) was placed at the isocenter of the scanner, and an air gap of 34.5 cm was used in lieu of a grid. Dilute iodine-based contrast agent was introduced into the phantoms using plastic vials. Data were acquired from 40 to 90 kVp at 10 kVp intervals. Due to the low mA available on the breast CT system, a large number of images (1000) were acquired in fluoroscopic mode, which allowed us to match the dose and noise properties for each kVp combinations by changing the number of images used for averaging. Preliminary results demonstrate that the best CNR2/dose is achieved with a 50 kVp low-energy image and a 90 kVp high-energy image. Consequently, radiation doses for contrast-enhanced mammography should be far lower than regular mammography. Since the spatial resolution requirements should also be lower than regular mammography, dual-energy contrast-enhanced mammography, when performed using the optimal technique factor, may indeed provide very similar diagnostic information as breast

Real-time 3-D contrast-enhanced transcranial ultrasound and aberration correction.

PubMed

Ivancevich, Nikolas M; Pinton, Gianmarco F; Nicoletto, Heather A; Bennett, Ellen; Laskowitz, Daniel T; Smith, Stephen W

2008-09-01

Contrast-enhanced (CE) transcranial ultrasound (US) and reconstructed 3-D transcranial ultrasound have shown advantages over traditional methods in a variety of cerebrovascular diseases. We present the results from a novel ultrasound technique, namely real-time 3-D contrast-enhanced transcranial ultrasound. Using real-time 3-D (RT3D) ultrasound and microbubble contrast agent, we scanned 17 healthy volunteers via a single temporal window and nine via the suboccipital window and report our detection rates for the major cerebral vessels. In 71% of subjects, both of our observers identified the ipsilateral circle of Willis from the temporal window, and in 59% we imaged the entire circle of Willis. From the suboccipital window, both observers detected the entire vertebrobasilar circulation in 22% of subjects, and in 44%, the basilar artery. After performing phase aberration correction on one subject, we were able to increase the diagnostic value of the scan, detecting a vessel not present in the uncorrected scan. These preliminary results suggest that RT3D CE transcranial US and RT3D CE transcranial US with phase aberration correction have the potential to greatly impact the field of neurosonology.

Real-Time 3D Contrast-Enhanced Transcranial Ultrasound and Aberration Correction

PubMed Central

Ivancevich, Nikolas M.; Pinton, Gianmarco F.; Nicoletto, Heather A.; Bennett, Ellen; Laskowitz, Daniel T.; Smith, Stephen W.

2008-01-01

Contrast-enhanced (CE) transcranial ultrasound (US) and reconstructed 3D transcranial ultrasound have shown advantages over traditional methods in a variety of cerebrovascular diseases. We present the results from a novel ultrasound technique, namely real-time 3D contrast-enhanced transcranial ultrasound. Using real-time 3D (RT3D) ultrasound and micro-bubble contrast agent, we scanned 17 healthy volunteers via a single temporal window and 9 via the sub-occipital window and report our detection rates for the major cerebral vessels. In 71% of subjects, both of our observers identified the ipsilateral circle of Willis from the temporal window, and in 59% we imaged the entire circle of Willis. From the sub-occipital window, both observers detected the entire vertebrobasilar circulation in 22% of subjects, and in 44% the basilar artery. After performing phase aberration correction on one subject, we were able to increase the diagnostic value of the scan, detecting a vessel not present in the uncorrected scan. These preliminary results suggest that RT3D CE transcranial US and RT3D CE transcranial US with phase aberration correction have the potential to greatly impact the field of neurosonology. PMID:18395321

Helium ion microscopy of graphene: beam damage, image quality and edge contrast

NASA Astrophysics Data System (ADS)

Fox, D.; Zhou, Y. B.; O'Neill, A.; Kumar, S.; Wang, J. J.; Coleman, J. N.; Duesberg, G. S.; Donegan, J. F.; Zhang, H. Z.

2013-08-01

A study to analyse beam damage, image quality and edge contrast in the helium ion microscope (HIM) has been undertaken. The sample investigated was graphene. Raman spectroscopy was used to quantify the disorder that can be introduced into the graphene as a function of helium ion dose. The effects of the dose on both freestanding and supported graphene were compared. These doses were then correlated directly to image quality by imaging graphene flakes at high magnification. It was found that a high magnification image with a good signal to noise ratio will introduce very significant sample damage. A safe imaging dose of the order of 1013 He+ cm-2 was established, with both graphene samples becoming highly defective at doses over 5 × 1014 He+ cm-2. The edge contrast of a freestanding graphene flake imaged in the HIM was then compared with the contrast of the same flake observed in a scanning electron microscope and a transmission electron microscope. Very strong edge sensitivity was observed in the HIM. This enhanced edge sensitivity over the other techniques investigated makes the HIM a powerful nanoscale dimensional metrology tool, with the capability of both fabricating and imaging features with sub-nanometre resolution.

Exploring silver as a contrast agent for contrast-enhanced dual-energy X-ray breast imaging

PubMed Central

Tsourkas, A; Maidment, A D A

2014-01-01

Objective: Through prior monoenergetic modelling, we have identified silver as a potential alternative to iodine in dual-energy (DE) X-ray breast imaging. The purpose of this study was to compare the performance of silver and iodine contrast agents in a commercially available DE imaging system through a quantitative analysis of signal difference-to-noise ratio (SDNR). Methods: A polyenergetic simulation algorithm was developed to model the signal intensity and noise. The model identified the influence of various technique parameters on SDNR. The model was also used to identify the optimal imaging techniques for silver and iodine, so that the two contrast materials could be objectively compared. Results: The major influences on the SDNR were the low-energy dose fraction and breast thickness. An increase in the value of either of these parameters resulted in a decrease in SDNR. The SDNR for silver was on average 43% higher than that for iodine when imaged at their respective optimal conditions, and 40% higher when both were imaged at the optimal conditions for iodine. Conclusion: A silver contrast agent should provide benefit over iodine, even when translated to the clinic without modification of imaging system or protocol. If the system were slightly modified to reflect the lower k-edge of silver, the difference in SDNR between the two materials would be increased. Advances in knowledge: These data are the first to demonstrate the suitability of silver as a contrast material in a clinical contrast-enhanced DE image acquisition system. PMID:24998157

Contrast enhancement of central nervous system lesions: multicenter intraindividual crossover comparative study of two MR contrast agents.

PubMed

Maravilla, Kenneth R; Maldjian, Joseph A; Schmalfuss, Ilona M; Kuhn, Matthew J; Bowen, Brian C; Wippold, Franz J; Runge, Val M; Knopp, Michael V; Kremer, Stephane; Wolansky, Leo J; Anzalone, Nicoletta; Essig, Marco; Gustafsson, Lars

2006-08-01

To prospectively compare gadobenate dimeglumine with gadopentetate dimeglumine (0.1 mmol per kilogram body weight) for enhanced magnetic resonance (MR) imaging of central nervous system (CNS) lesions. This study was HIPAA-compliant at U.S. centers and was conducted at all centers according to the Good Clinical Practice standard. Institutional review board and regulatory approval were granted; written informed consent was obtained. Seventy-nine men and 78 women (mean age, 50.5 years +/- 14.4 [standard deviation]) were randomized to group A (n = 78) or B (n = 79). Patients underwent two temporally separated 1.5-T MR imaging examinations. In randomized order, gadobenate followed by gadopentetate was administered in group A; order of administration was reversed in group B. Contrast agent administration (volume, speed of injection), imaging parameters before and after injection, and time between injections and postinjection acquisitions were identical for both examinations. Three blinded neuroradiologists evaluated images by using objective image interpretation criteria for diagnostic information end points (lesion border delineation, definition of disease extent, visualization of internal morphologic features of the lesion, enhancement of the lesion) and quantitative parameters (percentage of lesion enhancement, contrast-to-noise ratio [CNR]). Overall diagnostic preference in terms of lesion conspicuity, detectability, and diagnostic confidence was assessed. Between-group comparisons were performed with Wilcoxon signed rank test. Readers 1, 2, and 3 demonstrated overall preference for gadobenate in 75, 89, and 103 patients, compared with that for gadopentetate in seven, 10, and six patients, respectively (P < .0001). Significant (P < .0001) preference for gadobenate was demonstrated for diagnostic information end points, percentage of lesion enhancement, and CNR. Superiority of gadobenate was significant (P < .001) in patients with intraaxial and extraaxial lesions

Power port contrast medium flushing and trapping: impact of temperature, an in vitro experimental study.

PubMed

Guiffant, Gérard; Durussel, Jean Jacques; Flaud, Patrice; Royon, Laurent; Marcy, Pierre Yves; Merckx, Jacques

2013-01-01

The use of totally implantable venous access devices (TIVADs) certified as "high pressure resistant" or "power port" has begun to spread worldwide as a safe procedure for power contrast injection. Owing to the thermo-rheological properties of the contrast media, the primary aim of this work is to present an in vitro experimental impact study concerning the impact of the temperature level on flushing efficiency after contrast medium injection. Moreover, we report experimental data that confirms the role of needle bevel orientation. The secondary aim is to answer the following questions: Is there significant device contrast medium trapping after contrast medium injection? Is saline flushing efficient? And, finally, is it safe to inject contrast medium through an indwelled port catheter? The experimental results show that in addition to hydrodynamics, temperature is a key parameter for the efficiency of device flushing after contrast medium injection. It appears that this is the case when the cavity is incompletely rinsed after three calibrated flushing volumes of 10 mL saline solution, even by using the Huber needle bevel opposite to the port exit. This leads to a potentially important trapped volume of contrast medium in the port, and consequently to the possibility of subsequent salt precipitates and long term trisubstituted benzene nuclei delivery that might impair the solute properties, which may be further injected via the power port later on. We thus suggest, in TIVADS patients, the use of a temporary supplementary intravenous line rather than the port to perform contrast medium injections in daily radiology routine practice.

Power port contrast medium flushing and trapping: impact of temperature, an in vitro experimental study

PubMed Central

Guiffant, Gérard; Durussel, Jean Jacques; Flaud, Patrice; Royon, Laurent; Marcy, Pierre Yves; Merckx, Jacques

2013-01-01

Purpose The use of totally implantable venous access devices (TIVADs) certified as “high pressure resistant” or “power port” has begun to spread worldwide as a safe procedure for power contrast injection. Owing to the thermo-rheological properties of the contrast media, the primary aim of this work is to present an in vitro experimental impact study concerning the impact of the temperature level on flushing efficiency after contrast medium injection. Moreover, we report experimental data that confirms the role of needle bevel orientation. The secondary aim is to answer the following questions: Is there significant device contrast medium trapping after contrast medium injection? Is saline flushing efficient? And, finally, is it safe to inject contrast medium through an indwelled port catheter? Results The experimental results show that in addition to hydrodynamics, temperature is a key parameter for the efficiency of device flushing after contrast medium injection. It appears that this is the case when the cavity is incompletely rinsed after three calibrated flushing volumes of 10 mL saline solution, even by using the Huber needle bevel opposite to the port exit. This leads to a potentially important trapped volume of contrast medium in the port, and consequently to the possibility of subsequent salt precipitates and long term trisubstituted benzene nuclei delivery that might impair the solute properties, which may be further injected via the power port later on. Conclusion We thus suggest, in TIVADS patients, the use of a temporary supplementary intravenous line rather than the port to perform contrast medium injections in daily radiology routine practice. PMID:24043959

Quantitative evaluation of contrast-enhanced ultrasound after intravenous administration of a microbubble contrast agent for differentiation of benign and malignant thyroid nodules: assessment of diagnostic accuracy.

PubMed

Nemec, Ursula; Nemec, Stefan F; Novotny, Clemens; Weber, Michael; Czerny, Christian; Krestan, Christian R

2012-06-01

To investigate the diagnostic accuracy, through quantitative analysis, of contrast-enhanced ultrasound (CEUS), using a microbubble contrast agent, in the differentiation of thyroid nodules. This prospective study enrolled 46 patients with solitary, scintigraphically non-functional thyroid nodules. These patients were scheduled for surgery and underwent preoperative CEUS with pulse-inversion harmonic imaging after intravenous microbubble contrast medium administration. Using histology as a standard of reference, time-intensity curves of benign and malignant nodules were compared by means of peak enhancement and wash-out enhancement relative to the baseline intensity using a mixed model ANOVA. ROC analysis was performed to assess the diagnostic accuracy in the differentiation of benign and malignant nodules on CEUS. The complete CEUS data of 42 patients (31/42 [73.8%] benign and 11/42 [26.2%] malignant nodules) revealed a significant difference (P < 0.001) in enhancement between benign and malignant nodules. Furthermore, based on ROC analysis, CEUS demonstrated sensitivity of 76.9%, specificity of 84.8% and accuracy of 82.6%. Quantitative analysis of CEUS using a microbubble contrast agent allows the differentiation of benign and malignant thyroid nodules and may potentially serve, in addition to grey-scale and Doppler ultrasound, as an adjunctive tool in the assessment of patients with thyroid nodules. • Contrast-enhanced ultrasound (CEUS) helps differentiate between benign and malignant thyroid nodules. • Quantitative CEUS analysis yields sensitivity of 76.9% and specificity of 84.8%. • CEUS may be a potentially useful adjunct in assessing thyroid nodules.

Contrast-enhanced intravascular ultrasound pulse sequences for bandwidth-limited transducers.

PubMed

Maresca, David; Renaud, Guillaume; van Soest, Gijs; Li, Xiang; Zhou, Qifa; Shung, K Kirk; de Jong, Nico; van der Steen, Antonius F W

2013-04-01

We demonstrate two methods for vasa vasorum imaging using contrast-enhanced intravascular ultrasound, which can be performed using commercial catheters. Plaque neovascularization was recognized as an independent marker of coronary artery plaque vulnerability. IVUS-based methods to image the microvessels available to date require high bandwidth (-6 dB relative frequency bandwidth >70%), which are not routinely available commercially. We explored the potential of ultraharmonic imaging and chirp reversal imaging for vasa vasorum imaging. In vitro recordings were performed on a tissue-mimicking phantom using a commercial ultrasound contrast agent and a transducer with a center frequency of 34 MHz and a -6 dB relative bandwidth of 56%. Acoustic peak pressures <500 kPa were used. A tissue-mimicking phantom with channels down to 200 μm in diameter was successfully imaged by the two contrast detection sequences while the smallest channel stayed invisible in conventional intravascular ultrasound images. Ultraharmonic imaging provided the best contrast agent detection. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. All rights reserved.

Cumulative phase delay imaging for contrast-enhanced ultrasound tomography

NASA Astrophysics Data System (ADS)

Demi, Libertario; van Sloun, Ruud J. G.; Wijkstra, Hessel; Mischi, Massimo

2015-11-01

Standard dynamic-contrast enhanced ultrasound (DCE-US) imaging detects and estimates ultrasound-contrast-agent (UCA) concentration based on the amplitude of the nonlinear (harmonic) components generated during ultrasound (US) propagation through UCAs. However, harmonic components generation is not specific to UCAs, as it also occurs for US propagating through tissue. Moreover, nonlinear artifacts affect standard DCE-US imaging, causing contrast to tissue ratio reduction, and resulting in possible misclassification of tissue and misinterpretation of UCA concentration. Furthermore, no contrast-specific modality exists for DCE-US tomography; in particular speed-of-sound changes due to UCAs are well within those caused by different tissue types. Recently, a new marker for UCAs has been introduced. A cumulative phase delay (CPD) between the second harmonic and fundamental component is in fact observable for US propagating through UCAs, and is absent in tissue. In this paper, tomographic US images based on CPD are for the first time presented and compared to speed-of-sound US tomography. Results show the applicability of this marker for contrast specific US imaging, with cumulative phase delay imaging (CPDI) showing superior capabilities in detecting and localizing UCA, as compared to speed-of-sound US tomography. Cavities (filled with UCA) which were down to 1 mm in diameter were clearly detectable. Moreover, CPDI is free of the above mentioned nonlinear artifacts. These results open important possibilities to DCE-US tomography, with potential applications to breast imaging for cancer localization.

Cumulative phase delay imaging for contrast-enhanced ultrasound tomography.

PubMed

Demi, Libertario; van Sloun, Ruud J G; Wijkstra, Hessel; Mischi, Massimo

2015-11-07

Standard dynamic-contrast enhanced ultrasound (DCE-US) imaging detects and estimates ultrasound-contrast-agent (UCA) concentration based on the amplitude of the nonlinear (harmonic) components generated during ultrasound (US) propagation through UCAs. However, harmonic components generation is not specific to UCAs, as it also occurs for US propagating through tissue. Moreover, nonlinear artifacts affect standard DCE-US imaging, causing contrast to tissue ratio reduction, and resulting in possible misclassification of tissue and misinterpretation of UCA concentration. Furthermore, no contrast-specific modality exists for DCE-US tomography; in particular speed-of-sound changes due to UCAs are well within those caused by different tissue types. Recently, a new marker for UCAs has been introduced. A cumulative phase delay (CPD) between the second harmonic and fundamental component is in fact observable for US propagating through UCAs, and is absent in tissue. In this paper, tomographic US images based on CPD are for the first time presented and compared to speed-of-sound US tomography. Results show the applicability of this marker for contrast specific US imaging, with cumulative phase delay imaging (CPDI) showing superior capabilities in detecting and localizing UCA, as compared to speed-of-sound US tomography. Cavities (filled with UCA) which were down to 1 mm in diameter were clearly detectable. Moreover, CPDI is free of the above mentioned nonlinear artifacts. These results open important possibilities to DCE-US tomography, with potential applications to breast imaging for cancer localization.

Thermal x-ray diffraction and near-field phase contrast imaging

NASA Astrophysics Data System (ADS)

Li, Zheng; Classen, Anton; Peng, Tao; Medvedev, Nikita; Wang, Fenglin; Chapman, Henry N.; Shih, Yanhua

2017-10-01

Using higher-order coherence of thermal light sources, the resolution power of standard x-ray imaging techniques can be enhanced. In this work, we applied the higher-order measurement to far-field x-ray diffraction and near-field phase contrast imaging (PCI), in order to achieve superresolution in x-ray diffraction and obtain enhanced intensity contrast in PCI. The cost of implementing such schemes is minimal compared to the methods that achieve similar effects by using entangled x-ray photon pairs.

Thermal x-ray diffraction and near-field phase contrast imaging

DOE PAGES

Li, Zheng; Classen, Anton; Peng, Tao; ...

2017-12-27

Using higher-order coherence of thermal light sources, the resolution power of standard x-ray imaging techniques can be enhanced. Here in this work, we applied the higher-order measurement to far-field x-ray diffraction and near-field phase contrast imaging (PCI), in order to achieve superresolution in x-ray diffraction and obtain enhanced intensity contrast in PCI. The cost of implementing such schemes is minimal compared to the methods that achieve similar effects by using entangled x-ray photon pairs.

Investigation of the acute plantar fasciitis with contrast-enhanced ultrasound and shear wave elastography - first results.

PubMed

Putz, Franz Josef; Hautmann, Matthias G; Banas, Miriam C; Jung, Ernst Michael

2017-01-01

The plantar fasciitis is a common disease with a high prevalence in public and a frequent cause of heel pain. In our pilot study, we wanted to characterise the feasibility of shear-wave elastography and contrast-enhanced ultrasound (CEUS) in the assessment of the plantar fasciitis. 23 cases of painful heels were examined by B-Mode ultrasound, Power Doppler (PD), shear wave elastography and contrast-enhanced ultrasound before anti-inflammatory radiation. Time-intensity-curves were analysed by the integrated software. The results for area-under-the-curve (AUC), peak, time-to-peak (TTP) and mean-transit-time (MTT) were compared between the plantar fascia and the surrounding tissue. All cases showed thickening of the plantar fascia, in most cases with interstitial oedema (87.0%). Shear wave elastography showed inhomogeneous stiffness of the plantar fascia. 83.3% of cases showed a visible hyperperfusion in CEUS at the proximal plantar fascia in comparison to the surrounding tissue. This hyperperfusion could also be found in 75.0% of cases with no signs of vascularisation in PD. AUC (p = 0.0005) and peak (p = 0.037) were significantely higher in the plantar fascia than in the surrounding tissue. CEUS and shear wave elastography are new diagnostic tools in the assessment of plantar fasciitis and can provide quantitative parameters for monitoring therapy.

New innovations for contrast enhancement in electron microscopy

NASA Astrophysics Data System (ADS)

Mohan, A.

In this study two techniques for producing and improving contrast in Electron Microscopy are discussed. The first technique deals with the production of secondary contrast in a Variable Pressure SEM under poor vacuum conditions using the specimen current signal. A review of the prior work in this field shows that the presence of the gas ions in the microscope column results in the amplification of the specimen current signal which is enriched in secondary content. The focus of this study is to establish practical conditions for imaging samples in the microscope using specimen current with gas amplification. This is done by understanding the different variables in the microscope which affect the image formation process and then finding out optimum conditions for obtaining the best possible image, i.e., the image most enhanced in secondary contrast. A few 'real life' samples analyzed using this technique show that the gas amplified specimen current images contain secondary information and, in some cases, provide clear advantages to imaging with conventional secondary and backscattered detectors. The second technique dealing with the production of phase contrast in the TEM for extremely thin, electron transparent samples, is analyzed. A review of the literature regarding prior work in the field shows that, while the theoretical aspects of production of phase contrast in the TEM using a phase plate are well understood, there have been problems in practically implementing this in the microscope. One major assumption with most of the studies is that a fiber, partially coated with gold, results in the formation of point charges which is an essential requirement for symmetrically shifting the phase of the electron beam. The focus of this portion of the dissertation is to image the type of fields associated with such a phase plate using the technique of electron holography. It is found that there are two types of fields associated with a phase plate of this sort. One is a

Assessing tumor vascularization as a potential biomarker of imatinib resistance in gastrointestinal stromal tumors by dynamic contrast-enhanced magnetic resonance imaging.

PubMed

Consolino, Lorena; Longo, Dario Livio; Sciortino, Marianna; Dastrù, Walter; Cabodi, Sara; Giovenzana, Giovanni Battista; Aime, Silvio

2017-07-01

Most metastatic gastrointestinal stromal tumors (GISTs) develop resistance to the first-line imatinib treatment. Recently, increased vessel density and angiogenic markers were reported in GISTs with a poor prognosis, suggesting that angiogenesis is implicated in GIST tumor progression and resistance. The purpose of this study was to investigate the relationship between tumor vasculature and imatinib resistance in different GIST mouse models using a noninvasive magnetic resonance imaging (MRI) functional approach. Immunodeficient mice (n = 8 for each cell line) were grafted with imatinib-sensitive (GIST882 and GIST-T1) and imatinib-resistant (GIST430) human cell lines. Dynamic contrast-enhanced MRI (DCE-MRI) was performed on GIST xenografts to quantify tumor vessel permeability (K trans ) and vascular volume fraction (v p ). Microvessel density (MVD), permeability (mean dextran density, MDD), and angiogenic markers were evaluated by immunofluorescence and western blot assays. Dynamic contrast-enhanced magnetic resonance imaging showed significantly increased vessel density (P < 0.0001) and permeability (P = 0.0002) in imatinib-resistant tumors compared to imatinib-sensitive ones. Strong positive correlations were observed between MRI estimates, K trans and v p , and their related ex vivo values, MVD (r = 0.78 for K trans and r = 0.82 for v p ) and MDD (r = 0.77 for K trans and r = 0.94 for v p ). In addition, higher expression of vascular endothelial growth factor receptors (VEGFR2 and VEFGR3) was seen in GIST430. Dynamic contrast-enhanced magnetic resonance imaging highlighted marked differences in tumor vasculature and microenvironment properties between imatinib-resistant and imatinib-sensitive GISTs, as also confirmed by ex vivo assays. These results provide new insights into the role that DCE-MRI could play in GIST characterization and response to GIST treatment. Validation studies are needed to confirm these findings.

What is the underestimation of radiation dose to the pediatric thyroid gland from contrast enhanced CT, if contrast medium uptake is not taken into account?

PubMed

Perisinakis, Kostas; Pouli, Styliani; Tzedakis, Antonis; Spanakis, Kostas; Hatzidakis, Adam; Raissaki, Maria; Damilakis, John

2018-05-01

To assess the underestimation of radiation dose to the thyroid of children undergoing contrast enhanced CT if contrast medium uptake is not taken into account. 161 pediatric head, head & neck and chest CT examinations were retrospectively studied to identify those involving pre- and post-contrast imaging and thyroid inclusion in imaged volume. CT density of thyroid tissue in HU was measured in non-enhanced (NECT) and corresponding contrast-enhanced CT (CECT) images. Resulting CT number increase (ΔHU) was recorded for each patient and corresponded to a % w/w iodine concentration. The relation of %w/w iodine concentration to %dose increase induced by iodinated contrast uptake was derived by Monte Carlo simulation experiments. The thyroid gland was visible in 11 chest and 3 neck CT examinations involving both pre- and post-contrast imaging. The %w/w concentration of iodine in the thyroid tissue at the time of CECT acquisition was found to be 0.13%-0.58% w/w (mean = 0.26%). The %increase of dose to thyroid tissue was found to be linearly correlated to%w/w iodine uptake. The increase in radiation dose to thyroid due to contrast uptake ranged from 12% to 44%, with a mean value of 23%. The radiation dose to the pediatric thyroid from CECT exposure may be underestimated by up to 44% if contrast medium uptake is not taken into account. Meticulous demarcation of imaged volume in pediatric chest CT examinations is imperative to avoid unnecessary direct exposure of thyroid, especially in CT examinations following intravenous administration of contrast medium. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Development of low-dose photon-counting contrast-enhanced tomosynthesis with spectral imaging.

PubMed

Schmitzberger, Florian F; Fallenberg, Eva Maria; Lawaczeck, Rüdiger; Hemmendorff, Magnus; Moa, Elin; Danielsson, Mats; Bick, Ulrich; Diekmann, Susanne; Pöllinger, Alexander; Engelken, Florian J; Diekmann, Felix

2011-05-01

To demonstrate the feasibility of low-dose photon-counting tomosynthesis in combination with a contrast agent (contrast material-enhanced tomographic mammography) for the differentiation of breast cancer. All studies were approved by the institutional review board, and all patients provided written informed consent. A phantom model with wells of iodinated contrast material (3 mg of iodine per milliliter) 1, 2, 5, 10, and 15 mm in diameter was assessed. Nine patients with malignant lesions and one with a high-risk lesion (atypical papilloma) were included (all women; mean age, 60.7 years). A multislit photon-counting tomosynthesis system was utilized (spectral imaging) to produce both low- and high-energy tomographic data (below and above the k edge of iodine, respectively) in a single scan, which allowed for dual-energy visualization of iodine. Images were obtained prior to contrast material administration and 120 and 480 seconds after contrast material administration. Four readers independently assessed the images along with conventional mammograms, ultrasonographic images, and magnetic resonance images. Glandular dose was estimated. Contrast agent was visible in the phantom model with simulated spherical tumor diameters as small as 5 mm. The average glandular dose was measured as 0.42 mGy per complete spectral imaging tomosynthesis scan of one breast. Because there were three time points (prior to contrast medium administration and 120 and 480 seconds after contrast medium administration), this resulted in a total dose of 1.26 mGy for the whole procedure in the breast with the abnormality. Seven of 10 cases were categorized as Breast Imaging Reporting and Data System score of 4 or higher by all four readers when reviewing spectral images in combination with mammograms. One lesion near the chest wall was not captured on the spectral image because of a positioning problem. The use of contrast-enhanced tomographic mammography has been demonstrated successfully in

Chain of evidence generation for contrast enhancement in digital image forensics

NASA Astrophysics Data System (ADS)

Battiato, Sebastiano; Messina, Giuseppe; Strano, Daniela

2010-01-01

The quality of the images obtained by digital cameras has improved a lot since digital cameras early days. Unfortunately, it is not unusual in image forensics to find wrongly exposed pictures. This is mainly due to obsolete techniques or old technologies, but also due to backlight conditions. To extrapolate some invisible details a stretching of the image contrast is obviously required. The forensics rules to produce evidences require a complete documentation of the processing steps, enabling the replication of the entire process. The automation of enhancement techniques is thus quite difficult and needs to be carefully documented. This work presents an automatic procedure to find contrast enhancement settings, allowing both image correction and automatic scripting generation. The technique is based on a preprocessing step which extracts the features of the image and selects correction parameters. The parameters are thus saved through a JavaScript code that is used in the second step of the approach to correct the image. The generated script is Adobe Photoshop compliant (which is largely used in image forensics analysis) thus permitting the replication of the enhancement steps. Experiments on a dataset of images are also reported showing the effectiveness of the proposed methodology.

Contrast-enhanced swallow study sensitivity for anastomotic leak detection in post-esophagectomy patients.

PubMed

Mejía-Rivera, S; Pérez-Marroquín, S A; Cortés-González, R; Medina-Franco, H

2018-03-07

Esophagectomy is a highly invasive surgery and one of its postoperative complications is anastomotic leakage, occurring in 53% of cases. The aim of the present study was to determine the sensitivity of the contrast-enhanced swallow study as a method for diagnosing anastomotic leak in patients that underwent esophagectomy. The present retrospective study included the case records of patients that underwent esophagectomy with reconstruction and cervical anastomosis at the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán within the time frame of January 1, 2000 and May 31, 2006. Demographic, clinical, and laboratory data emphasizing clinical and radiographic anastomotic leak detection were identified. Descriptive statistics were carried out and contrast-enhanced swallow study sensitivity for diagnosing leakage was calculated. Seventy patients were included in the analysis. The mean age of the patients was 50.6 years, 51 of the patients were men (72.86%), and 19 were women (27.14%). Indications for surgery were benign lesion in 29 patients (41.4%) and malignant lesion in 41 (58.6%). A total of 44.3% of the patients presented with a comorbidity, with diabetes mellitus and high blood pressure standing out. Thirty patients (42.85%) presented with anastomotic leak. Contrast-enhanced swallow study sensitivity for leak detection was 43.33%. The diagnostic sensitivity of the contrast-enhanced swallow study was very low. Therefore, we recommend the discontinuation of its routine use as a method for diagnosing anastomotic leaks. Copyright © 2018 Asociación Mexicana de Gastroenterología. Publicado por Masson Doyma México S.A. All rights reserved.

Computer-aided detection of bladder mass within non-contrast-enhanced region of CT Urography (CTU)

NASA Astrophysics Data System (ADS)

Cha, Kenny H.; Hadjiiski, Lubomir M.; Chan, Heang-Ping; Caoili, Elaine M.; Cohan, Richard H.; Weizer, Alon; Zhou, Chuan

2016-03-01

We are developing a computer-aided detection system for bladder cancer in CT urography (CTU). We have previously developed methods for detection of bladder masses within the contrast-enhanced region of the bladder. In this study, we investigated methods for detection of bladder masses within the non-contrast enhanced region. The bladder was first segmented using a newly developed deep-learning convolutional neural network in combination with level sets. The non-contrast-enhanced region was separated from the contrast-enhanced region with a maximum-intensityprojection- based method. The non-contrast region was smoothed and a gray level threshold was employed to segment the bladder wall and potential masses. The bladder wall was transformed into a straightened thickness profile, which was analyzed to identify lesion candidates as a prescreening step. The lesion candidates were segmented using our autoinitialized cascaded level set (AI-CALS) segmentation method, and 27 morphological features were extracted for each candidate. Stepwise feature selection with simplex optimization and leave-one-case-out resampling were used for training and validation of a false positive (FP) classifier. In each leave-one-case-out cycle, features were selected from the training cases and a linear discriminant analysis (LDA) classifier was designed to merge the selected features into a single score for classification of the left-out test case. A data set of 33 cases with 42 biopsy-proven lesions in the noncontrast enhanced region was collected. During prescreening, the system obtained 83.3% sensitivity at an average of 2.4 FPs/case. After feature extraction and FP reduction by LDA, the system achieved 81.0% sensitivity at 2.0 FPs/case, and 73.8% sensitivity at 1.5 FPs/case.

Enhancing Tabletop X-Ray Phase Contrast Imaging with Nano-Fabrication

PubMed Central

Miao, Houxun; Gomella, Andrew A.; Harmon, Katherine J.; Bennett, Eric E.; Chedid, Nicholas; Znati, Sami; Panna, Alireza; Foster, Barbara A.; Bhandarkar, Priya; Wen, Han

2015-01-01

X-ray phase-contrast imaging is a promising approach for improving soft-tissue contrast and lowering radiation dose in biomedical applications. While current tabletop imaging systems adapt to common x-ray tubes and large-area detectors by employing absorptive elements such as absorption gratings or monolithic crystals to filter the beam, we developed nanometric phase gratings which enable tabletop x-ray far-field interferometry with only phase-shifting elements, leading to a substantial enhancement in the performance of phase contrast imaging. In a general sense the method transfers the demands on the spatial coherence of the x-ray source and the detector resolution to the feature size of x-ray phase masks. We demonstrate its capabilities in hard x-ray imaging experiments at a fraction of clinical dose levels and present comparisons with the existing Talbot-Lau interferometer and with conventional digital radiography. PMID:26315891

Optimization of contrast-enhanced spectral mammography depending on clinical indication.

PubMed

Dromain, Clarisse; Canale, Sandra; Saab-Puong, Sylvie; Carton, Ann-Katherine; Muller, Serge; Fallenberg, Eva Maria

2014-10-01

The objective is to optimize low-energy (LE) and high-energy (HE) exposure parameters of contrast-enhanced spectral mammography (CESM) examinations in four different clinical applications for which different levels of average glandular dose (AGD) and ratios between LE and total doses are required. The optimization was performed on a Senographe DS with a SenoBright® upgrade. Simulations were performed to find the optima by maximizing the contrast-to-noise ratio (CNR) on the recombined CESM image using different targeted doses and LE image quality. The linearity between iodine concentration and CNR as well as the minimal detectable iodine concentration was assessed. The image quality of the LE image was assessed on the CDMAM contrast-detail phantom. Experiments confirmed the optima found on simulation. The CNR was higher for each clinical indication than for SenoBright®, including the screening indication for which the total AGD was 22% lower. Minimal iodine concentrations detectable in the case of a 3-mm-diameter round tumor were 12.5% lower than those obtained for the same dose in the clinical routine. LE image quality satisfied EUREF acceptable limits for threshold contrast. This newly optimized set of acquisition parameters allows increased contrast detectability compared to parameters currently used without a significant loss in LE image quality.

Dynamic contrast-enhanced diffuse optical tomography (DCE-DOT): experimental validation with a dynamic phantom

NASA Astrophysics Data System (ADS)

Burcin Unlu, Mehmet; Lin, Yuting; Gulsen, Gultekin

2009-11-01

Dynamic contrast-enhanced diffuse optical tomography (DCE-DOT) can provide spatially resolved enhancement kinetics of an optical contrast agent. We undertook a systematic phantom study to evaluate the effects of the geometrical parameters such as the depth and size of the inclusion as well as the optical parameters of the background on the recovered enhancement kinetics of the most commonly used optical contrast agent, indocyanine green (ICG). For this purpose a computer-controlled dynamic phantom was constructed. An ICG-intralipid-water mixture was circulated through the inclusions while the DCE-DOT measurements were acquired with a temporal resolution of 16 s. The same dynamic study was repeated using inclusions of different sizes located at different depths. In addition to this, the effect of non-scattering regions was investigated by placing a second inclusion filled with water in the background. The phantom studies confirmed that although the peak enhancement varied substantially for each case, the recovered injection and dilution rates obtained from the percentage enhancement maps agreed within 15% independent of not only the depth and the size of the inclusion but also the presence of a non-scattering region in the background. Although no internal structural information was used in these phantom studies, it may be necessary to use it for small objects buried deep in tissue. However, the different contrast mechanisms of optical and other imaging modalities as well as imperfect co-registration between both modalities may lead to potential errors in the structural a priori. Therefore, the effect of erroneous selection of structural priors was investigated as the final step. Again, the injection and dilution rates obtained from the percentage enhancement maps were also immune to the systematic errors introduced by erroneous selection of the structural priors, e.g. choosing the diameter of the inclusion 20% smaller increased the peak enhancement 60% but changed

Contrast-enhanced ultrasonography for the detection of joint vascularity in arthritis--subjective grading versus computer-aided objective quantification.

PubMed

Klauser, A S; Franz, M; Bellmann Weiler, R; Gruber, J; Hartig, F; Mur, E; Wick, M C; Jaschke, W

2011-12-01

To compare joint inflammation assessment using subjective grading of power Doppler ultrasonography (PDUS) and contrast-enhanced ultrasonography (CEUS) versus computer-aided objective CEUS quantification. 37 joints of 28 patients with arthritis of different etiologies underwent B-mode ultrasonography, PDUS, and CEUS using a second-generation contrast agent. Synovial thickness, extent of vascularized pannus and intensity of vascularization were included in a 4-point PDUS and CEUS grading system. Subjective CEUS and PDUS scores were compared to computer-aided objective CEUS quantification using Qontrast® software for the calculation of the signal intensity (SI) and the ratio of SI for contrast enhancement. The interobserver agreement for subjective scoring was good to excellent (κ = 0.8 - 1.0; P < 0.0001). Computer-aided objective CEUS quantification correlated statistically significantly with subjective CEUS (P < 0.001) and PDUS grading (P < 0.05). The Qontrast® SI ratio correlated with subjective CEUS (P < 0.02) and PDUS grading (P < 0.03). Clinical activity did not correlate with vascularity or synovial thickening (P = N. S.) and no correlation between synovial thickening and vascularity extent could be found, neither using PDUS nor CEUS (P = N. S.). Both subjective CEUS grading and objective CEUS quantification are valuable for assessing joint vascularity in arthritis and computer-aided CEUS quantification may be a suitable objective tool for therapy follow-up in arthritis. © Georg Thieme Verlag KG Stuttgart · New York.

Practical method and device for enhancing pulse contrast ratio for lasers and electron accelerators

DOEpatents

Zhang, Shukui; Wilson, Guy

2014-09-23

An apparatus and method for enhancing pulse contrast ratios for drive lasers and electron accelerators. The invention comprises a mechanical dual-shutter system wherein the shutters are placed sequentially in series in a laser beam path. Each shutter of the dual shutter system has an individually operated trigger for opening and closing the shutter. As the triggers are operated individually, the delay between opening and closing first shutter and opening and closing the second shutter is variable providing for variable differential time windows and enhancement of pulse contrast ratio.

Comparison of arterial input functions measured from ultra-fast dynamic contrast enhanced MRI and dynamic contrast enhanced computed tomography in prostate cancer patients

NASA Astrophysics Data System (ADS)

Wang, Shiyang; Lu, Zhengfeng; Fan, Xiaobing; Medved, Milica; Jiang, Xia; Sammet, Steffen; Yousuf, Ambereen; Pineda, Federico; Oto, Aytekin; Karczmar, Gregory S.

2018-02-01

The purpose of this study was to evaluate the accuracy of arterial input functions (AIFs) measured from dynamic contrast enhanced (DCE) MRI following a low dose of contrast media injection. The AIFs measured from DCE computed tomography (CT) were used as ‘gold standard’. A total of twenty patients received CT and MRI scans on the same day. Patients received 120 ml Iohexol in DCE-CT and a low dose of (0.015 mM kg-1) of gadobenate dimeglumine in DCE-MRI. The AIFs were measured in the iliac artery and normalized to the CT and MRI contrast agent doses. To correct for different temporal resolution and sampling periods of CT and MRI, an empirical mathematical model (EMM) was used to fit the AIFs first. Then numerical AIFs (AIFCT and AIFMRI) were calculated based on fitting parameters. The AIFMRI was convolved with a ‘contrast agent injection’ function (AIFMRICON ) to correct for the difference between MRI and CT contrast agent injection times (~1.5 s versus 30 s). The results show that the EMMs accurately fitted AIFs measured from CT and MRI. There was no significant difference (p  >  0.05) between the maximum peak amplitude of AIFs from CT (22.1  ±  4.1 mM/dose) and MRI after convolution (22.3  ±  5.2 mM/dose). The shapes of the AIFCT and AIFMRICON were very similar. Our results demonstrated that AIFs can be accurately measured by MRI following low dose contrast agent injection.

Gadolinium Deposition in Human Brain Tissues after Contrast-enhanced MR Imaging in Adult Patients without Intracranial Abnormalities.

PubMed

McDonald, Robert J; McDonald, Jennifer S; Kallmes, David F; Jentoft, Mark E; Paolini, Michael A; Murray, David L; Williamson, Eric E; Eckel, Laurence J

2017-11-01

Purpose To determine whether gadolinium deposits in neural tissues of patients with intracranial abnormalities following intravenous gadolinium-based contrast agent (GBCA) exposure might be related to blood-brain barrier integrity by studying adult patients with normal brain pathologic characteristics. Materials and Methods After obtaining antemortem consent and institutional review board approval, the authors compared postmortem neuronal tissue samples from five patients who had undergone four to 18 gadolinium-enhanced magnetic resonance (MR) examinations between 2005 and 2014 (contrast group) with samples from 10 gadolinium-naive patients who had undergone at least one MR examination during their lifetime (control group). All patients in the contrast group had received gadodiamide. Neuronal tissues from the dentate nuclei, pons, globus pallidus, and thalamus were harvested and analyzed with inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy with energy-dispersive x-ray spectroscopy, and light microscopy to quantify, localize, and assess the effects of gadolinium deposition. Results Tissues from the four neuroanatomic regions of gadodiamide-exposed patients contained 0.1-19.4 μg of gadolinium per gram of tissue in a statistically significant dose-dependent relationship (globus pallidus: ρ = 0.90, P = .04). In contradistinction, patients in the control group had undetectable levels of gadolinium with ICP-MS. All patients had normal brain pathologic characteristics at autopsy. Three patients in the contrast group had borderline renal function (estimated glomerular filtration rate <45 mL/min/1.73 m 2 ) and hepatobiliary dysfunction at MR examination. Gadolinium deposition in the contrast group was localized to the capillary endothelium and neuronal interstitium and, in two cases, within the nucleus of the cell. Conclusion Gadolinium deposition in neural tissues after GBCA administration occurs in the absence of intracranial

Characteristic MRI findings in hyperglycaemia-induced seizures: diagnostic value of contrast-enhanced fluid-attenuated inversion recovery imaging.

PubMed

Lee, E J; Kim, K K; Lee, E K; Lee, J E

2016-12-01

To describe characteristic magnetic resonance imaging (MRI) abnormalities in hyperglycaemia-induced seizures, and evaluate the diagnostic value of contrast-enhanced fluid-attenuated inversion recovery (FLAIR) imaging. Possible underlying mechanisms of this condition are also discussed. Eleven patients with hyperglycaemia-induced seizures and MRI abnormalities were retrospectively studied. Clinical manifestations, laboratory findings, MRI findings, and clinical outcomes were analysed. All patients, except one, presented with focal seizures, simple or complex partial seizures, or negative motor seizures. All patients had long-standing uncontrolled diabetes mellitus. The MRI abnormalities observed acutely were focal subcortical hypointensities on T2-weighted imaging and FLAIR imaging in all patients with overlying cortical gyral T2 hyperintensities in five. Focal overlying cortical or leptomeningeal enhancement on contrast-enhanced T1-weighted imaging or contrast-enhanced FLAIR imaging was observed in all patients. Contrast-enhanced FLAIR imaging was superior to contrast-enhanced T1-weighted imaging for detecting characteristic cortical or leptomeningeal enhancement. Diffusion-weighted imaging showed mildly restricted diffusion in four of five patients with cortical gyral T2 hyperintensity. In nine patients, the lesions were localised in the parietal or parieto-occipital lobes. The other two patients showed localised precentral gyral lesions. After treatment, the neurological symptoms, including the seizures, improved in all patients. On clinical recovery, the subcortical T2 hypointensity, gyral or leptomeningeal enhancement, and overlying cortical T2 hyperintensities resolved. Recognition of these radiological abnormalities in patients with hyperglycaemia-induced seizures is important in restricting unwarranted investigations and initiating early therapy. These patients generally have a good prognosis. Copyright © 2016 The Royal College of Radiologists. Published by

Single-layer and dual-layer contrast-enhanced mammography using amorphous selenium flat panel detectors

NASA Astrophysics Data System (ADS)

Allec, N.; Abbaszadeh, S.; Karim, K. S.

2011-09-01

The accumulation of injected contrast agents allows the image enhancement of lesions through the use of contrast-enhanced mammography. In this technique, the combination of two acquired images is used to create an enhanced image. There exist several methods to acquire the images to be combined, which include dual energy subtraction using a single detection layer that suffers from motion artifacts due to patient motion between image acquisition. To mitigate motion artifacts, a detector composed of two layers may be used to simultaneously acquire the low and high energy images. In this work, we evaluate both of these methods using amorphous selenium as the detection material to find the system parameters (tube voltage, filtration, photoconductor thickness and relative intensity ratio) leading to the optimal performance. We then compare the performance of the two detectors under the variation of contrast agent concentration, tumor size and dose. The detectability was found to be most comparable at the lower end of the evaluated factors. The single-layer detector not only led to better contrast, due to its greater spectral separation capabilities, but also had lower quantum noise. The single-layer detector was found to have a greater detectability by a factor of 2.4 for a 2.5 mm radius tumor having a contrast agent concentration of 1.5 mg ml-1 in a 4.5 cm thick 50% glandular breast. The inclusion of motion artifacts in the comparison is part of ongoing research efforts.

Single-layer and dual-layer contrast-enhanced mammography using amorphous selenium flat panel detectors.

PubMed

Allec, N; Abbaszadeh, S; Karim, K S

2011-09-21

The accumulation of injected contrast agents allows the image enhancement of lesions through the use of contrast-enhanced mammography. In this technique, the combination of two acquired images is used to create an enhanced image. There exist several methods to acquire the images to be combined, which include dual energy subtraction using a single detection layer that suffers from motion artifacts due to patient motion between image acquisition. To mitigate motion artifacts, a detector composed of two layers may be used to simultaneously acquire the low and high energy images. In this work, we evaluate both of these methods using amorphous selenium as the detection material to find the system parameters (tube voltage, filtration, photoconductor thickness and relative intensity ratio) leading to the optimal performance. We then compare the performance of the two detectors under the variation of contrast agent concentration, tumor size and dose. The detectability was found to be most comparable at the lower end of the evaluated factors. The single-layer detector not only led to better contrast, due to its greater spectral separation capabilities, but also had lower quantum noise. The single-layer detector was found to have a greater detectability by a factor of 2.4 for a 2.5 mm radius tumor having a contrast agent concentration of 1.5 mg ml(-1) in a 4.5 cm thick 50% glandular breast. The inclusion of motion artifacts in the comparison is part of ongoing research efforts.

Dynamic-contrast-enhanced-MRI with extravasating contrast reagent: Rat cerebral glioma blood volume determination

NASA Astrophysics Data System (ADS)

Li, Xin; Rooney, William D.; Várallyay, Csanád G.; Gahramanov, Seymur; Muldoon, Leslie L.; Goodman, James A.; Tagge, Ian J.; Selzer, Audrey H.; Pike, Martin M.; Neuwelt, Edward A.; Springer, Charles S.

2010-10-01

The accurate mapping of the tumor blood volume (TBV) fraction ( vb) is a highly desired imaging biometric goal. It is commonly thought that achieving this is difficult, if not impossible, when small molecule contrast reagents (CRs) are used for the T1-weighted (Dynamic-Contrast-Enhanced) DCE-MRI technique. This is because angiogenic malignant tumor vessels allow facile CR extravasation. Here, a three-site equilibrium water exchange model is applied to DCE-MRI data from the cerebrally-implanted rat brain U87 glioma, a tumor exhibiting rapid CR extravasation. Analyses of segments of the (and the entire) DCE data time-course with this "shutter-speed" pharmacokinetic model, which admits finite water exchange kinetics, allow TBV estimation from the first-pass segment. Pairwise parameter determinances were tested with grid searches of 2D parametric error surfaces. Tumor blood volume ( vb), as well as ve (the extracellular, extravascular space volume fraction), and Ktrans (a CR extravasation rate measure) parametric maps are presented. The role of the Patlak Plot in DCE-MRI is also considered.

Local contrast-enhanced MR images via high dynamic range processing.

PubMed

Chandra, Shekhar S; Engstrom, Craig; Fripp, Jurgen; Neubert, Ales; Jin, Jin; Walker, Duncan; Salvado, Olivier; Ho, Charles; Crozier, Stuart

2018-09-01

To develop a local contrast-enhancing and feature-preserving high dynamic range (HDR) image processing algorithm for multichannel and multisequence MR images of multiple body regions and tissues, and to evaluate its performance for structure visualization, bias field (correction) mitigation, and automated tissue segmentation. A multiscale-shape and detail-enhancement HDR-MRI algorithm is applied to data sets of multichannel and multisequence MR images of the brain, knee, breast, and hip. In multisequence 3T hip images, agreement between automatic cartilage segmentations and corresponding synthesized HDR-MRI series were computed for mean voxel overlap established from manual segmentations for a series of cases. Qualitative comparisons between the developed HDR-MRI and standard synthesis methods were performed on multichannel 7T brain and knee data, and multisequence 3T breast and knee data. The synthesized HDR-MRI series provided excellent enhancement of fine-scale structure from multiple scales and contrasts, while substantially reducing bias field effects in 7T brain gradient echo, T 1 and T 2 breast images and 7T knee multichannel images. Evaluation of the HDR-MRI approach on 3T hip multisequence images showed superior outcomes for automatic cartilage segmentations with respect to manual segmentation, particularly around regions with hyperintense synovial fluid, across a set of 3D sequences. The successful combination of multichannel/sequence MR images into a single-fused HDR-MR image format provided consolidated visualization of tissues within 1 omnibus image, enhanced definition of thin, complex anatomical structures in the presence of variable or hyperintense signals, and improved tissue (cartilage) segmentation outcomes. © 2018 International Society for Magnetic Resonance in Medicine.

Method of Improved Fuzzy Contrast Combined Adaptive Threshold in NSCT for Medical Image Enhancement

PubMed Central

Yang, Jie; Kasabov, Nikola

2017-01-01

Noises and artifacts are introduced to medical images due to acquisition techniques and systems. This interference leads to low contrast and distortion in images, which not only impacts the effectiveness of the medical image but also seriously affects the clinical diagnoses. This paper proposes an algorithm for medical image enhancement based on the nonsubsampled contourlet transform (NSCT), which combines adaptive threshold and an improved fuzzy set. First, the original image is decomposed into the NSCT domain with a low-frequency subband and several high-frequency subbands. Then, a linear transformation is adopted for the coefficients of the low-frequency component. An adaptive threshold method is used for the removal of high-frequency image noise. Finally, the improved fuzzy set is used to enhance the global contrast and the Laplace operator is used to enhance the details of the medical images. Experiments and simulation results show that the proposed method is superior to existing methods of image noise removal, improves the contrast of the image significantly, and obtains a better visual effect. PMID:28744464

A predictive software tool for optimal timing in contrast enhanced carotid MR angiography

NASA Astrophysics Data System (ADS)

Moghaddam, Abbas N.; Balawi, Tariq; Habibi, Reza; Panknin, Christoph; Laub, Gerhard; Ruehm, Stefan; Finn, J. Paul

2008-03-01

A clear understanding of the first pass dynamics of contrast agents in the vascular system is crucial in synchronizing data acquisition of 3D MR angiography (MRA) with arrival of the contrast bolus in the vessels of interest. We implemented a computational model to simulate contrast dynamics in the vessels using the theory of linear time-invariant systems. The algorithm calculates a patient-specific impulse response for the contrast concentration from time-resolved images following a small test bolus injection. This is performed for a specific region of interest and through deconvolution of the intensity curve using the long division method. Since high spatial resolution 3D MRA is not time-resolved, the method was validated on time-resolved arterial contrast enhancement in Multi Slice CT angiography. For 20 patients, the timing of the contrast enhancement of the main bolus was predicted by our algorithm from the response to the test bolus, and then for each case the predicted time of maximum intensity was compared to the corresponding time in the actual scan which resulted in an acceptable agreement. Furthermore, as a qualitative validation, the algorithm's predictions of the timing of the carotid MRA in 20 patients with high quality MRA were correlated with the actual timing of those studies. We conclude that the above algorithm can be used as a practical clinical tool to eliminate guesswork and to replace empiric formulae by a priori computation of patient-specific timing of data acquisition for MR angiography.

3D non-contrast-enhanced ECG-gated MR angiography of the lower extremities with dual-source radiofrequency transmission at 3.0 T: Intraindividual comparison with contrast-enhanced MR angiography in PAOD patients.

PubMed

Rasper, Michael; Wildgruber, Moritz; Settles, Marcus; Eckstein, Hans-Henning; Zimmermann, Alexander; Reeps, Christian; Rummeny, Ernst J; Huber, Armin M

2016-09-01

To compare prospectively image quality and diagnostic confidence of flow-sensitive 3D turbo spin echo (TSE)-based non-contrast-enhanced MR angiography (NE-MRA) at 3.0 T using dual-source radiofrequency (RF) transmission with contrast-enhanced MRA (CE-MRA) in patients with peripheral arterial occlusive disease (PAOD). After consent was obtained, 35 patients (mean age 69.1 ± 10.6 years) with PAOD stage II-IV underwent NE-MRA followed by CE-MRA. Signal-to-noise ratio and contrast-to-noise ratio were calculated. Subjective image quality was independently assessed by two radiologists and stenosis scoring was performed in 875 arterial segments. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for stenosis classification were calculated using CE-MRA as a reference method. Diagnostic agreement with CE-MRA was evaluated with Cohen's kappa statistics. NE-MRA provided high objective and subjective image quality at all levels of the arterial tree. Sensitivity and specificity for the detection of relevant stenosis was 91 % and 89 %, respectively; the NPV was 96 % and the PPV 78 %. There was good concordance between CE-MRA and NE-MRA in stenosis scoring. 3D electrocardiography (ECG)-gated TSE NE-MRA with patient-adaptive dual-source RF transmission at 3.0 T is a promising alternative for PAOD patients with contraindications for gadolinium-based contrast agents. It offers high sensitivity and NPV values in the detection of clinically relevant arterial stenosis. • Flow-sensitive TSE NE-MRA is a promising technique for PAOD evaluation. • Diagnostic accuracy is comparable to contrast-enhanced MRA. • NE-MRA eliminates the risk of NSF in patients with renal insufficiency. • Costs arising from the use of contrast agents can be avoided.

Modified global and modified linear contrast stretching algorithms: new colour contrast enhancement techniques for microscopic analysis of malaria slide images.

PubMed

Abdul-Nasir, Aimi Salihah; Mashor, Mohd Yusoff; Mohamed, Zeehaida

2012-01-01

Malaria is one of the serious global health problem, causing widespread sufferings and deaths in various parts of the world. With the large number of cases diagnosed over the year, early detection and accurate diagnosis which facilitates prompt treatment is an essential requirement to control malaria. For centuries now, manual microscopic examination of blood slide remains the gold standard for malaria diagnosis. However, low contrast of the malaria and variable smears quality are some factors that may influence the accuracy of interpretation by microbiologists. In order to reduce this problem, this paper aims to investigate the performance of the proposed contrast enhancement techniques namely, modified global and modified linear contrast stretching as well as the conventional global and linear contrast stretching that have been applied on malaria images of P. vivax species. The results show that the proposed modified global and modified linear contrast stretching techniques have successfully increased the contrast of the parasites and the infected red blood cells compared to the conventional global and linear contrast stretching. Hence, the resultant images would become useful to microbiologists for identification of various stages and species of malaria.

Contrast Enhanced Maximum Intensity Projection Ultrasound Imaging for Assessing Angiogenesis in Murine Glioma and Breast Tumor Models: A Comparative Study

PubMed Central

Forsberg, Flemming; Ro, Raymond J.; Fox, Traci B; Liu, Ji-Bin; Chiou, See-Ying; Potoczek, Magdalena; Goldberg, Barry B

2010-01-01

The purpose of this study was to prospectively compare noninvasive, quantitative measures of vascularity obtained from 4 contrast enhanced ultrasound (US) techniques to 4 invasive immunohistochemical markers of tumor angiogenesis in a large group of murine xenografts. Glioma (C6) or breast cancer (NMU) cells were implanted in 144 rats. The contrast agent Optison (GE Healthcare, Princeton, NJ) was injected in a tail vein (dose: 0.4ml/kg). Power Doppler imaging (PDI), pulse-subtraction harmonic imaging (PSHI), flash-echo imaging (FEI), and Microflow imaging (MFI; a technique creating maximum intensity projection images over time) was performed with an Aplio scanner (Toshiba America Medical Systems, Tustin, CA) and a 7.5 MHz linear array. Fractional tumor neovascularity was calculated from digital clips of contrast US, while the relative area stained was calculated from specimens. Results were compared using a factorial, repeated measures ANOVA, linear regression and z-tests. The tortuous morphology of tumor neovessels was visualized better with MFI than with the other US modes. Cell line, implantation method and contrast US imaging technique were significant parameters in the ANOVA model (p<0.05). The strongest correlation determined by linear regression in the C6 model was between PSHI and percent area stained with CD31 (r=0.37, p<0.0001). In the NMU model the strongest correlation was between FEI and COX-2 (r=0.46, p<0.0001). There were no statistically significant differences between correlations obtained with the various US methods (p>0.05). In conclusion, the largest study of contrast US of murine xenografts to date has been conducted and quantitative contrast enhanced US measures of tumor neovascularity in glioma and breast cancer xenograft models appear to provide a noninvasive marker for angiogenesis; although the best method for monitoring angiogenesis was not conclusively established. PMID:21144542

Fuzzy pulmonary vessel segmentation in contrast enhanced CT data

NASA Astrophysics Data System (ADS)

Kaftan, Jens N.; Kiraly, Atilla P.; Bakai, Annemarie; Das, Marco; Novak, Carol L.; Aach, Til

2008-03-01

Pulmonary vascular tree segmentation has numerous applications in medical imaging and computer-aided diagnosis (CAD), including detection and visualization of pulmonary emboli (PE), improved lung nodule detection, and quantitative vessel analysis. We present a novel approach to pulmonary vessel segmentation based on a fuzzy segmentation concept, combining the strengths of both threshold and seed point based methods. The lungs of the original image are first segmented and a threshold-based approach identifies core vessel components with a high specificity. These components are then used to automatically identify reliable seed points for a fuzzy seed point based segmentation method, namely fuzzy connectedness. The output of the method consists of the probability of each voxel belonging to the vascular tree. Hence, our method provides the possibility to adjust the sensitivity/specificity of the segmentation result a posteriori according to application-specific requirements, through definition of a minimum vessel-probability required to classify a voxel as belonging to the vascular tree. The method has been evaluated on contrast-enhanced thoracic CT scans from clinical PE cases and demonstrates overall promising results. For quantitative validation we compare the segmentation results to randomly selected, semi-automatically segmented sub-volumes and present the resulting receiver operating characteristic (ROC) curves. Although we focus on contrast enhanced chest CT data, the method can be generalized to other regions of the body as well as to different imaging modalities.

High power, high contrast hybrid femtosecond laser systems

NASA Astrophysics Data System (ADS)

Dabu, Razvan

2017-06-01

For many research applications a very high laser intensity of more than 1022 W/cm2 in the focused beam is required. If a laser intensity of about 1011W/cm2 is reached on the target before the main laser pulse, the generated pre-plasma disturbs the experiment. High power femtosecond lasers must be tightly focused to get high intensity and in the same time must have a high enough intensity contrast of the temporally compressed amplified pulses. Reaching an intensity contrast in the range of 1012 represents a challenging task for a Ti:sapphire CPA laser. Hybrid femtosecond lasers combine optical parametric chirped pulsed amplification (OPCPA) in nonlinear crystals with the chirped pulse amplification (CPA) in laser active media. OPCPA provides large amplification spectral bandwidth and improves the intensity contrast of the amplified pulses. A key feature of these systems consists in the adaptation of the parametric amplification phase-matching bandwidth of nonlinear crystals to the spectral gain bandwidth of laser amplifying Ti:sapphire crystals. OPCPA in BBO crystals up to mJ energy level in the laser Front-End, followed by CPA up to ten/hundred Joules in large aperture Ti:sapphire crystals, represents a suitable solution for PW-class femtosecond lasers. The configuration and expected output beam characteristics of the hybrid amplification 2 × 10 PW ELI-NP laser are described.

Optimization of contrast-enhanced spectral mammography depending on clinical indication

PubMed Central

Dromain, Clarisse; Canale, Sandra; Saab-Puong, Sylvie; Carton, Ann-Katherine; Muller, Serge; Fallenberg, Eva Maria

2014-01-01

Abstract. The objective is to optimize low-energy (LE) and high-energy (HE) exposure parameters of contrast-enhanced spectral mammography (CESM) examinations in four different clinical applications for which different levels of average glandular dose (AGD) and ratios between LE and total doses are required. The optimization was performed on a Senographe DS with a SenoBright® upgrade. Simulations were performed to find the optima by maximizing the contrast-to-noise ratio (CNR) on the recombined CESM image using different targeted doses and LE image quality. The linearity between iodine concentration and CNR as well as the minimal detectable iodine concentration was assessed. The image quality of the LE image was assessed on the CDMAM contrast-detail phantom. Experiments confirmed the optima found on simulation. The CNR was higher for each clinical indication than for SenoBright®, including the screening indication for which the total AGD was 22% lower. Minimal iodine concentrations detectable in the case of a 3-mm-diameter round tumor were 12.5% lower than those obtained for the same dose in the clinical routine. LE image quality satisfied EUREF acceptable limits for threshold contrast. This newly optimized set of acquisition parameters allows increased contrast detectability compared to parameters currently used without a significant loss in LE image quality. PMID:26158058

Can contrast media increase organ doses in CT examinations? A clinical study.

PubMed

Amato, Ernesto; Salamone, Ignazio; Naso, Serena; Bottari, Antonio; Gaeta, Michele; Blandino, Alfredo

2013-06-01

The purpose of this article is to quantify the CT radiation dose increment in five organs resulting from the administration of iodinated contrast medium. Forty consecutive patients who underwent both un-enhanced and contrast-enhanced thoracoabdominal CT were included in our retrospective study. The dose increase between CT before and after contrast agent administration was evaluated in the portal phase for the thyroid, liver, spleen, pancreas, and kidneys by applying a previously validated method. An increase in radiation dose was noted in all organs studied. Average dose increments were 19% for liver, 71% for kidneys, 33% for spleen and pancreas, and 41% for thyroid. Kidneys exhibited the maximum dose increment, whereas the pancreas showed the widest variance because of the differences in fibro-fatty involution. Finally, thyroids with high attenuation values on unenhanced CT showed a lower Hounsfield unit increase and, thus, a smaller increment in the dose. Our study showed an increase in radiation dose in several parenchymatous tissues on contrast-enhanced CT. Our method allowed us to evaluate the dose increase from the change in attenuation measured in Hounsfield units. Because diagnostic protocols require multiple acquisitions after the contrast agent administration, such a dose increase should be considered when optimizing these protocols.

Contrast-enhanced postmortem computed tomography in clinical pathology: enhanced value of 20 clinical autopsies.

PubMed

Westphal, Saskia E; Apitzsch, Jonas C; Penzkofer, Tobias; Kuhl, Christiane K; Mahnken, Andreas H; Knüchel, Ruth

2014-09-01

Postmortem computed tomography (PMCT) is a modern tool that complements autopsy diagnostics. In clinical autopsies, a major cause of death is cardiovascular disease. To improve the performance of PMCT in cardiovascular disease, full body angiography was developed (PMCT angiography [PMCTA]). Twenty PMCTA scans generated before autopsy were compared with native PMCT and clinical autopsy. The objective of the study was to quantify the additional diagnostic value of adding angiography to native imaging and to compare PMCT and PMCTA findings to autopsy findings. The diagnosis of the cause of death was identical or overlapped in 80% of the cases that used PMCTA and 70% that used PMCT. The additional diagnostic yield given by PMCT and PMCTA in combination with autopsy was 55%. PMCT yielded additional diagnoses in the musculoskeletal system. The greatest additional diagnostic value of PMCTA was in association with cardiovascular diagnoses. The accuracy of PMCTA for cardiac causes of death was 80%, and the positive predictive value was 90%. The findings indicate that native PMCT cannot display the cardiovascular system sufficiently clearly for high-quality diagnostic assessment. However, PMCTA is a powerful tool in autopsy cases with a history of cardiovascular disease and/or a suspected cardiovascular cause of death. The combination of PMCTA and clinical autopsy enhances diagnostic quality and completeness of the autopsy report. Furthermore, in cases without consent or with a restricted consent for clinical autopsy, PMCTA has the potential to provide information on cardiovascular causes of death. Copyright © 2014 Elsevier Inc. All rights reserved.

Quantifying alkane emissions in the Eagle Ford Shale using boundary layer enhancement

NASA Astrophysics Data System (ADS)

Roest, Geoffrey; Schade, Gunnar

2017-09-01

The Eagle Ford Shale in southern Texas is home to a booming unconventional oil and gas industry, the climate and air quality impacts of which remain poorly quantified due to uncertain emission estimates. We used the atmospheric enhancement of alkanes from Texas Commission on Environmental Quality volatile organic compound monitors across the shale, in combination with back trajectory and dispersion modeling, to quantify C2-C4 alkane emissions for a region in southern Texas, including the core of the Eagle Ford, for a set of 68 days from July 2013 to December 2015. Emissions were partitioned into raw natural gas and liquid storage tank sources using gas and headspace composition data, respectively, and observed enhancement ratios. We also estimate methane emissions based on typical ethane-to-methane ratios in gaseous emissions. The median emission rate from raw natural gas sources in the shale, calculated as a percentage of the total produced natural gas in the upwind region, was 0.7 % with an interquartile range (IQR) of 0.5-1.3 %, below the US Environmental Protection Agency's (EPA) current estimates. However, storage tanks contributed 17 % of methane emissions, 55 % of ethane, 82 % percent of propane, 90 % of n-butane, and 83 % of isobutane emissions. The inclusion of liquid storage tank emissions results in a median emission rate of 1.0 % (IQR of 0.7-1.6 %) relative to produced natural gas, overlapping the current EPA estimate of roughly 1.6 %. We conclude that emissions from liquid storage tanks are likely a major source for the observed non-methane hydrocarbon enhancements in the Northern Hemisphere.

Enhancement of crop photosynthesis by diffuse light: quantifying the contributing factors

PubMed Central

Li, T.; Heuvelink, E.; Dueck, T. A.; Janse, J.; Gort, G.; Marcelis, L. F. M.

2014-01-01

Background and Aims Plants use diffuse light more efficiently than direct light. However, experimental comparisons between diffuse and direct light have been obscured by co-occurring differences in environmental conditions (e.g. light intensity). This study aims to analyse the factors that contribute to an increase in crop photosynthesis in diffuse light and to quantify their relative contribution under different levels of diffuseness at similar light intensities. The hypothesis is that the enhancement of crop photosynthesis in diffuse light results not only from the direct effects of more uniform vertical and horizontal light distribution in the crop canopy, but also from crop physiological and morphological acclimation. Methods Tomato (Solanum lycopersicum) crops were grown in three greenhouse compartments that were covered by glass with different degrees of light diffuseness (0, 45 and 71 % of the direct light being converted into diffuse light) while maintaining similar light transmission. Measurements of horizontal and vertical photosynthetic photon flux density (PPFD) distribution in the crop, leaf photosynthesis light response curves and leaf area index (LAI) were used to quantify each factor's contribution to an increase in crop photosynthesis in diffuse light. In addition, leaf temperature, photoinhibition, and leaf biochemical and anatomical properties were studied. Key Results The highest degree of light diffuseness (71 %) increased the calculated crop photosynthesis by 7·2 %. This effect was mainly attributed to a more uniform horizontal (33 % of the total effect) and vertical PPFD distribution (21 %) in the crop. In addition, plants acclimated to the high level of diffuseness by gaining a higher photosynthetic capacity of leaves in the middle of the crop and a higher LAI, which contributed 23 and 13 %, respectively, to the total increase in crop photosynthesis in diffuse light. Moreover, diffuse light resulted in lower leaf temperatures and less

Enhancement of crop photosynthesis by diffuse light: quantifying the contributing factors.

PubMed

Li, T; Heuvelink, E; Dueck, T A; Janse, J; Gort, G; Marcelis, L F M

2014-07-01

Plants use diffuse light more efficiently than direct light. However, experimental comparisons between diffuse and direct light have been obscured by co-occurring differences in environmental conditions (e.g. light intensity). This study aims to analyse the factors that contribute to an increase in crop photosynthesis in diffuse light and to quantify their relative contribution under different levels of diffuseness at similar light intensities. The hypothesis is that the enhancement of crop photosynthesis in diffuse light results not only from the direct effects of more uniform vertical and horizontal light distribution in the crop canopy, but also from crop physiological and morphological acclimation. Tomato (Solanum lycopersicum) crops were grown in three greenhouse compartments that were covered by glass with different degrees of light diffuseness (0, 45 and 71 % of the direct light being converted into diffuse light) while maintaining similar light transmission. Measurements of horizontal and vertical photosynthetic photon flux density (PPFD) distribution in the crop, leaf photosynthesis light response curves and leaf area index (LAI) were used to quantify each factor's contribution to an increase in crop photosynthesis in diffuse light. In addition, leaf temperature, photoinhibition, and leaf biochemical and anatomical properties were studied. The highest degree of light diffuseness (71 %) increased the calculated crop photosynthesis by 7·2 %. This effect was mainly attributed to a more uniform horizontal (33 % of the total effect) and vertical PPFD distribution (21 %) in the crop. In addition, plants acclimated to the high level of diffuseness by gaining a higher photosynthetic capacity of leaves in the middle of the crop and a higher LAI, which contributed 23 and 13 %, respectively, to the total increase in crop photosynthesis in diffuse light. Moreover, diffuse light resulted in lower leaf temperatures and less photoinhibition at the top of the canopy when

Clinical performance of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced pediatric abdominal MR angiography

PubMed Central

Yousaf, Ufra; Hsiao, Albert; Cheng, Joseph Y.; Alley, Marcus T.; Lustig, Michael; Pauly, John M.; Vasanawala, Shreyas S.

2015-01-01

Background Pediatric contrast-enhanced MR angiography is often limited by respiration, other patient motion and compromised spatiotemporal resolution. Objective To determine the reliability of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast enhanced MR angiography method for depicting abdominal arterial anatomy in young children. Materials and methods With IRB approval and informed consent, we retrospectively identified 27 consecutive children (16 males and 11 females; mean age: 3.8 years, range: 14 days to 8.4 years) referred for contrast enhanced MR angiography at our institution, who had undergone free-breathing spatiotemporally accelerated time-resolved contrast enhanced MR angiography studies. An radio-frequency-spoiled gradient echo sequence with Cartesian variable density k-space sampling and radial view ordering, intrinsic motion navigation and intermittent fat suppression was developed. Images were reconstructed with soft-gated parallel imaging locally low-rank method to achieve both motion correction and high spatiotemporal resolution. Quality of delineation of 13 abdominal arteries in the reconstructed images was assessed independently by two radiologists on a five-point scale. Ninety-five percent confidence intervals of the proportion of diagnostically adequate cases were calculated. Interobserver agreements were also analyzed. Results Eleven out of 13 arteries achieved acceptable image quality (mean score range: 3.9–5.0) for both readers. Fair to substantial interobserver agreement was reached on nine arteries. Conclusion Free-breathing spatiotemporally accelerated 3-D time-resolved contrast enhanced MR angiography frequently yields diagnostic image quality for most abdominal arteries for pediatric contrast enhanced MR angiography. PMID:26040509

High Energy Resolution Hyperspectral X-Ray Imaging for Low-Dose Contrast-Enhanced Digital Mammography.

PubMed

Pani, Silvia; Saifuddin, Sarene C; Ferreira, Filipa I M; Henthorn, Nicholas; Seller, Paul; Sellin, Paul J; Stratmann, Philipp; Veale, Matthew C; Wilson, Matthew D; Cernik, Robert J

2017-09-01

Contrast-enhanced digital mammography (CEDM) is an alternative to conventional X-ray mammography for imaging dense breasts. However, conventional approaches to CEDM require a double exposure of the patient, implying higher dose, and risk of incorrect image registration due to motion artifacts. A novel approach is presented, based on hyperspectral imaging, where a detector combining positional and high-resolution spectral information (in this case based on Cadmium Telluride) is used. This allows simultaneous acquisition of the two images required for CEDM. The approach was tested on a custom breast-equivalent phantom containing iodinated contrast agent (Niopam 150®). Two algorithms were used to obtain images of the contrast agent distribution: K-edge subtraction (KES), providing images of the distribution of the contrast agent with the background structures removed, and a dual-energy (DE) algorithm, providing an iodine-equivalent image and a water-equivalent image. The high energy resolution of the detector allowed the selection of two close-by energies, maximising the signal in KES images, and enhancing the visibility of details with the low surface concentration of contrast agent. DE performed consistently better than KES in terms of contrast-to-noise ratio of the details; moreover, it allowed a correct reconstruction of the surface concentration of the contrast agent in the iodine image. Comparison with CEDM with a conventional detector proved the superior performance of hyperspectral CEDM in terms of the image quality/dose tradeoff.

Contrast-enhanced ultrasound in portal venous system aneurysms: a multi-center study.

PubMed

Tana, Claudio; Dietrich, Christoph F; Badea, Radu; Chiorean, Liliana; Carrieri, Vincenzo; Schiavone, Cosima

2014-12-28

To investigate contrast-enhanced ultrasound (CEUS) findings in portal venous system aneurysms (PVSAs). In this multi-center, retrospective, case series study, we evaluated CEUS features of seven cases of PVSAs that were found incidentally on conventional ultrasound in the period 2007-2013. Three Ultrasound Centers were involved (Chieti, Italy, Bad Mergentheim, Germany, and Cluj-Napoca, Romania). All patients underwent CEUS with Sonovue(®) (Bracco, Milan, Italy) at a standard dose of 2.4 mL, followed by 10 mL of 0.9% saline solution. The examinations were performed using multifrequency transducers and low mechanical index. We considered aneurysmal a focal dilatation of the portal venous system with a size that was significantly greater than the remaining segments of the same vein, and that was equal or larger than 21 mm for the extrahepatic segments of portal venous system, main portal vein and bifurcation, and 9 mm for the intrahepatic branches. After contrast agent injection, all PVSAs were not enhanced in the arterial phase (starting 8-22 s). All PVSAs were then rapidly enhanced in the early portal venous phase (starting three to five seconds after the arterial phase, 11-30 s), with persistence and slow washout of the contrast agent in the late phase (starting 120 s). In all patients, CEUS confirmed the presence of a "to-and-fro" flow by showing a swirling pattern within the dilatation in the early portal venous phase. CEUS also improved the delineation of the lumen, and was reliable in showing its patency degree and integrity of walls. In one patient, CEUS showed a partial enhancement of the lumen with a uniformly nonenhancing area in the portal venous and late phases, suggesting thrombosis. In our case series, we found that CEUS could be useful in the assessment and follow-up of a PVSA. Further studies are needed to validate its diagnostic accuracy.

In Vivo High-Frequency Contrast-Enhanced Ultrasonography of Choroidal Melanoma in Rabbits: Imaging Features and Histopathologic Correlations

PubMed Central

Kang, Shin J.; Zhang, Qing; Patel, Samirkumar R.; Berezovsky, Damian; Yang, Hua; Wang, Yanggan; Grossniklaus, Hans E.

2013-01-01

Purpose To evaluate the utility of in vivo imaging of rabbit model of choroidal melanoma utilizing high-frequency contrast-enhanced ultrasound (HF-CE-US) with 2-or 3-dimensional modes, and to correlate the sonographic findings with histopathologic characteristics. Methods Five New Zealand white rabbits which were immunosuppressed with daily cyclosporin A were inoculated into their right eyes with aliquots of 1.5×106 / 50 µL of 92.1 human uveal melanoma cells cultured in RPMI. At week 4, the tumor-bearing eyes were imaged using high-frequency ultrasound with microbubble contrast agent to determine the 2-dimensional tumor size and relative blood volume and by 3-dimensional mode to determine tumor volume. Histologic tumor burden was quantified in enucleated eyes by ImageJ software, and microvascular density (MVD) was determined by counting vascular channels in PAS without hematoxylin sections. Results Utilizing HF-CE-US, melanomas were visualized as relatively hyperechoic regions in the images. The correlation coefficients of sonographic size or volume compared with histologic area were 0.72 and 0.70, respectively. The sonographic tumor relative blood volume correlated with the histologic tumor vascularity (R2=0.92, P=0.04) Conclusions There is a positive correlation between in vivo sonographic tumor volume/size and histologic tumor size in our rabbit choroidal melanoma model. HF-CE-US corresponds to microvascular density and blood volume. PMID:23645822

Comparison of the Diagnostic Accuracy of DSC- and Dynamic Contrast-Enhanced MRI in the Preoperative Grading of Astrocytomas.

PubMed

Nguyen, T B; Cron, G O; Perdrizet, K; Bezzina, K; Torres, C H; Chakraborty, S; Woulfe, J; Jansen, G H; Sinclair, J; Thornhill, R E; Foottit, C; Zanette, B; Cameron, I G

2015-11-01

Dynamic contrast-enhanced MR imaging parameters can be biased by poor measurement of the vascular input function. We have compared the diagnostic accuracy of dynamic contrast-enhanced MR imaging by using a phase-derived vascular input function and "bookend" T1 measurements with DSC MR imaging for preoperative grading of astrocytomas. This prospective study included 48 patients with a new pathologic diagnosis of an astrocytoma. Preoperative MR imaging was performed at 3T, which included 2 injections of 5-mL gadobutrol for dynamic contrast-enhanced and DSC MR imaging. During dynamic contrast-enhanced MR imaging, both magnitude and phase images were acquired to estimate plasma volume obtained from phase-derived vascular input function (Vp_Φ) and volume transfer constant obtained from phase-derived vascular input function (K(trans)_Φ) as well as plasma volume obtained from magnitude-derived vascular input function (Vp_SI) and volume transfer constant obtained from magnitude-derived vascular input function (K(trans)_SI). From DSC MR imaging, corrected relative CBV was computed. Four ROIs were placed over the solid part of the tumor, and the highest value among the ROIs was recorded. A Mann-Whitney U test was used to test for difference between grades. Diagnostic accuracy was assessed by using receiver operating characteristic analysis. Vp_ Φ and K(trans)_Φ values were lower for grade II compared with grade III astrocytomas (P < .05). Vp_SI and K(trans)_SI were not significantly different between grade II and grade III astrocytomas (P = .08-0.15). Relative CBV and dynamic contrast-enhanced MR imaging parameters except for K(trans)_SI were lower for grade III compared with grade IV (P ≤ .05). In differentiating low- and high-grade astrocytomas, we found no statistically significant difference in diagnostic accuracy between relative CBV and dynamic contrast-enhanced MR imaging parameters. In the preoperative grading of astrocytomas, the diagnostic accuracy of dynamic

Small-bowel MRI in children and young adults with Crohn disease: retrospective head-to-head comparison of contrast-enhanced and diffusion-weighted MRI.

PubMed

Neubauer, Henning; Pabst, Thomas; Dick, Anke; Machann, Wolfram; Evangelista, Laura; Wirth, Clemens; Köstler, Herbert; Hahn, Dietbert; Beer, Meinrad

2013-01-01

Small-bowel MRI based on contrast-enhanced T1-weighted sequences has been challenged by diffusion-weighted imaging (DWI) for detection of inflammatory bowel lesions and complications in patients with Crohn disease. To evaluate free-breathing DWI, as compared to contrast-enhanced MRI, in children, adolescents and young adults with Crohn disease. This retrospective study included 33 children and young adults with Crohn disease ages 17 ± 3 years (mean ± standard deviation) and 27 matched controls who underwent small-bowel MRI with contrast-enhanced T1-weighted sequences and DWI at 1.5 T. The detectability of Crohn manifestations was determined. Concurrent colonoscopy as reference was available in two-thirds of the children with Crohn disease. DWI and contrast-enhanced MRI correctly identified 32 and 31 patients, respectively. All 22 small-bowel lesions and all Crohn complications were detected. False-positive findings (two on DWI, one on contrast-enhanced MRI), compared to colonoscopy, were a result of large-bowel lumen collapse. Inflammatory wall thickening was comparable on DWI and contrast-enhanced MRI. DWI was superior to contrast-enhanced MRI for detection of lesions in 27% of the assessed bowel segments and equal to contrast-enhanced MRI in 71% of segments. DWI facilitates fast, accurate and comprehensive workup in Crohn disease without the need for intravenous administration of contrast medium. Contrast-enhanced MRI is superior in terms of spatial resolution and multiplanar acquisition.

Contrast-enhanced ultrasound features of hepatocellular carcinoma not detected during the screening procedure.

PubMed

Dong, Yi; Wang, Wen-Ping; Mao, Feng; Dietrich, Christoph

2017-08-01

Aim  The aim of this retrospective study is to report on the characteristics of contrast-enhanced ultrasound (CEUS) of primarily not detected hepatocellular carcinoma (HCC) during the screening procedure of patients at risk. Methods  Sixty-four patients with a finally solitary and histologically proven HCC not detected HCC during the screening procedure were retrospectively analyzed. Most of HCC lesions (90.6 %, 58/64) measured < 20 mm in diameter. All HCC lesions were not detected during the initial screening procedure but suspected using contrast-enhanced magnetic resonance imaging. The final gold standard was biopsy or surgery with histological examination. Results  On CEUS, 62/64 (96.8 %) of HCC were characterized as an obviously hyperenhanced lesion in arterial phase, and 41/64 (64.1 %) of HCC were characterized as hypoenhancing lesions in the portal venous and late phases. During the arterial phase of CEUS, 96.8 % of HCC displayed homogeneous hyperenhancement. Knowing the CEUS and magnetic resonance imaging findings, 45/64 (70.3 %) could have been detected using B-mode ultrasound (BMUS). Conclusion  BMUS as a screening procedure is generally accepted. Contrast-enhanced imaging modalities have improved detection and characterization of HCC. Homogeneous hyperenhancement during the arterial phase and mild washout are indicative for HCC in liver cirrhosis. © Georg Thieme Verlag KG Stuttgart · New York.

Dual-energy contrast enhanced digital breast tomosynthesis: concept, method, and evaluation on phantoms

NASA Astrophysics Data System (ADS)

Puong, Sylvie; Patoureaux, Fanny; Iordache, Razvan; Bouchevreau, Xavier; Muller, Serge

2007-03-01

In this paper, we present the development of dual-energy Contrast-Enhanced Digital Breast Tomosynthesis (CEDBT). A method to produce background clutter-free slices from a set of low and high-energy projections is introduced, along with a scheme for the determination of the optimal low and high-energy techniques. Our approach consists of a dual-energy recombination of the projections, with an algorithm that has proven its performance in Contrast-Enhanced Digital Mammography1 (CEDM), followed by an iterative volume reconstruction. The aim is to eliminate the anatomical background clutter and to reconstruct slices where the gray level is proportional to the local iodine volumetric concentration. Optimization of the low and high-energy techniques is performed by minimizing the total glandular dose to reach a target iodine Signal Difference to Noise Ratio (SDNR) in the slices. In this study, we proved that this optimization could be done on the projections, by consideration of the SDNR in the projections instead of the SDNR in the slices, and verified this with phantom measurements. We also discuss some limitations of dual-energy CEDBT, due to the restricted angular range for the projection views, and to the presence of scattered radiation. Experiments on textured phantoms with iodine inserts were conducted to assess the performance of dual-energy CEDBT. Texture contrast was nearly completely removed and the iodine signal was enhanced in the slices.

Noninvasive evaluation of active lower gastrointestinal bleeding: comparison between contrast-enhanced MDCT and 99mTc-labeled RBC scintigraphy.

PubMed

Zink, Stephen I; Ohki, Stephen K; Stein, Barry; Zambuto, Domenic A; Rosenberg, Ronald J; Choi, Jenny J; Tubbs, Daniel S

2008-10-01

The purpose of our study was to compare contrast-enhanced MDCT and (99m)Tc-labeled RBC scanning for the evaluation of active lower gastrointestinal bleeding. Over 17 months, 55 patients (32 men, 23 women; age range, 21-92 years) were evaluated prospectively with contrast-enhanced MDCT using 100 mL of iopromide 300 mg I/mL. Technetium-99m-labeled RBC scans were obtained on 41 of 55 patients and select patients underwent angiography for attempted embolization. Each imaging technique was reviewed in a blinded fashion for sensitivity for detection of active bleeding as well as the active lower gastrointestinal bleeding location. Findings were positive on both examinations in eight patients and negative on both examinations in 20 patients. Findings were positive on contrast-enhanced MDCT and negative on (99m)Tc-labeled RBC in two patients; findings were negative on contrast-enhanced MDCT and positive on (99m)Tc-labeled RBC in 11 patients. Statistics showed significant disagreement, with simple agreement = 68.3%, kappa = 0.341, and p = 0.014. Sixteen of 60 (26.7%) contrast-enhanced MDCT scans were positive prospectively, with all accurately localizing the site of bleeding and identification of the underlying lesion in eight of 16 (50%). Nineteen of 41 (46.3%) (99m)Tc-labeled RBC scans were positive. Eighteen of 41 matched patients went on to angiography. In four of these 18 (22.2%) patients, the site of bleeding was confirmed by angiography, but in 14 of 18 (77.8%), the findings were negative. Contrast-enhanced MDCT and (99m)Tc-labeled RBC scanning show significant disagreement for evaluation of active lower gastrointestinal bleeding. Contrast-enhanced MDCT appears effective for detection and localization in cases of active lower gastrointestinal bleeding in which hemorrhage is active at the time of CT.

Interactive lesion segmentation on dynamic contrast enhanced breast MRI using a Markov model

NASA Astrophysics Data System (ADS)

Wu, Qiu; Salganicoff, Marcos; Krishnan, Arun; Fussell, Donald S.; Markey, Mia K.

2006-03-01

The purpose of this study is to develop a method for segmenting lesions on Dynamic Contrast-Enhanced (DCE) breast MRI. DCE breast MRI, in which the breast is imaged before, during, and after the administration of a contrast agent, enables a truly 3D examination of breast tissues. This functional angiogenic imaging technique provides noninvasive assessment of microcirculatory characteristics of tissues in addition to traditional anatomical structure information. Since morphological features and kinetic curves from segmented lesions are to be used for diagnosis and treatment decisions, lesion segmentation is a key pre-processing step for classification. In our study, the ROI is defined by a bounding box containing the enhancement region in the subtraction image, which is generated by subtracting the pre-contrast image from 1st post-contrast image. A maximum a posteriori (MAP) estimate of the class membership (lesion vs. non-lesion) for each voxel is obtained using the Iterative Conditional Mode (ICM) method. The prior distribution of the class membership is modeled as a multi-level logistic model, a Markov Random Field model in which the class membership of each voxel is assumed to depend upon its nearest neighbors only. The likelihood distribution is assumed to be Gaussian. The parameters of each Gaussian distribution are estimated from a dozen voxels manually selected as representative of the class. The experimental segmentation results demonstrate anatomically plausible breast tissue segmentation and the predicted class membership of voxels from the interactive segmentation algorithm agrees with the manual classifications made by inspection of the kinetic enhancement curves. The proposed method is advantageous in that it is efficient, flexible, and robust.

Thermoelectric power factor enhancement by ionized nanoparticle scattering

NASA Astrophysics Data System (ADS)

Bahk, Je-Hyeong; Bian, Zhixi; Zebarjadi, Mona; Santhanam, Parthiban; Ram, Rajeev; Shakouri, Ali

2011-08-01

We show theoretically that the thermoelectric power factor can be enhanced in degenerate semiconductors when embedded nanoparticles donate carriers to the matrix and replace conventional impurity dopants as scattering centers. Nanoparticle scattering rates calculated by the partial wave method indicate a mobility enhancement over materials with equivalent doping by isolated ionized impurities while the Seebeck coefficient remains nearly intact. We find that the thermoelectric power factor of In0.53Ga0.47As from 300 K to 800 K is enhanced by 15% - 30% by nanoparticles 3-4 nm in diameter.

Contrast-enhanced Spectral Mammography: Technique, Indications, and Clinical Applications.

PubMed

Bhimani, Chandni; Matta, Danielle; Roth, Robyn G; Liao, Lydia; Tinney, Elizabeth; Brill, Kristin; Germaine, Pauline

2017-01-01

Contrast-enhanced spectral mammography (CESM) combines the benefits of full field digital mammography with the concept of tumor angiogenesis. Technique and practical applications of CESM are discussed. An overview of the technique is followed by a demonstration of practical applications of CESM in our practice. We have successfully implemented CESM into our practice as a screening, diagnostic, staging, and treatment response tool. It is important to understand the technique of CESM and how to incorporate it into practice. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Preliminary studies of enhanced contrast radiography in anatomy and embryology of insects with Elettra synchrotron light

NASA Astrophysics Data System (ADS)

Hönnicke, M. G.; Foerster, L. A.; Navarro-Silva, M. A.; Menk, R.-H.; Rigon, L.; Cusatis, C.

2005-08-01

Enhanced contrast X-ray imaging is achieved by exploiting the real part of the refraction index, which is responsible for the phase shifts, in addition to the imaginary part, which is responsible for the absorption. Such techniques are called X-ray phase contrast imaging. An analyzer-based X-ray phase contrast imaging set-up with Diffraction Enhanced Imaging processing (DEI) were used for preliminary studies in anatomy and embryology of insects. Parasitized stinkbug and moth eggs used as control agents of pests in vegetables and adult stinkbugs and mosquitoes ( Aedes aegypti) were used as samples. The experimental setup was mounted in the SYRMEP beamline at ELETTRA. Images were obtained using a high spatial resolution CCD detector (pixel size 14×14 μm 2) coupled with magnifying optics. Analyzer-based X-ray phase contrast images (PCI) and edge detection images show contrast and details not observed with conventional synchrotron radiography and open the possibility for future study in the embryonic development of insects.

Baseline Testing of the Ultracapacitor Enhanced Photovoltaic Power Station

NASA Technical Reports Server (NTRS)

Eichenberg, Dennis J.; Kolacz, John S.; Tavernelli, Paul F.

2001-01-01

The NASA John H. Glenn Research Center is developing an advanced ultracapacitor enhanced photovoltaic power station. Goals of this effort include maximizing photovoltaic power generation efficiency and extending the life of photovoltaic energy storage systems. Unique aspects of the power station include the use of a solar tracker, and ultracapacitors for energy storage. The photovoltaic power station is seen as a way to provide electric power in remote locations that would otherwise not have electric power, provide independence form utility systems, reduce pollution, reduce fossil fuel consumption, and reduce operating costs. The work was done under the Hybrid Power Management (HPM) Program, which includes the Hybrid Electric Transit Bus (HETB), and the E-Bike. The power station complements the E-Bike extremely well in that it permits the charging of the vehicle batteries in remote locations. Other applications include scientific research and medical power sources in isolated regions. The power station is an inexpensive approach to advance the state of the art in power technology in a practical application. The project transfers space technology to terrestrial use via nontraditional partners, and provides power system data valuable for future space applications. A description of the ultracapacitor enhanced power station, the results of performance testing and future power station development plans is the subject of this report. The report concludes that the ultracapacitor enhanced power station provides excellent performance, and that the implementation of ultracapacitors in the power system can provide significant performance improvements.

Very low cost real time histogram-based contrast enhancer utilizing fixed-point DSP processing

NASA Astrophysics Data System (ADS)

McCaffrey, Nathaniel J.; Pantuso, Francis P.

1998-03-01

A real time contrast enhancement system utilizing histogram- based algorithms has been developed to operate on standard composite video signals. This low-cost DSP based system is designed with fixed-point algorithms and an off-chip look up table (LUT) to reduce the cost considerably over other contemporary approaches. This paper describes several real- time contrast enhancing systems advanced at the Sarnoff Corporation for high-speed visible and infrared cameras. The fixed-point enhancer was derived from these high performance cameras. The enhancer digitizes analog video and spatially subsamples the stream to qualify the scene's luminance. Simultaneously, the video is streamed through a LUT that has been programmed with the previous calculation. Reducing division operations by subsampling reduces calculation- cycles and also allows the processor to be used with cameras of nominal resolutions. All values are written to the LUT during blanking so no frames are lost. The enhancer measures 13 cm X 6.4 cm X 3.2 cm, operates off 9 VAC and consumes 12 W. This processor is small and inexpensive enough to be mounted with field deployed security cameras and can be used for surveillance, video forensics and real- time medical imaging.

Quantifying the Sensitivity of the Production of Environmental Externalities to Market-Based Interventions in the Power Sector

NASA Astrophysics Data System (ADS)

Peer, R.; Sanders, K.

2017-12-01

The optimization function that governs the dispatching of power generators to meet electricity demand minimizes the marginal cost of electricity generation without regard to the environmental or public health damages caused by power production. Although technologies exist for reducing the externalities resulting from electricity generation at power plants, current solutions typically raise the cost of power production or introduce operational challenges for the grid. This research quantifies the trade-offs and couplings between the cooling water, greenhouse gas emissions, and air quality impacts of different power generating technologies under business as usual market conditions, as well as a series of market-based interventions aimed to reduce the production of those externalities. Using publicly available data from the US Environmental Protection Agency (EPA) and the US Energy Information Administration (EIA) for power plant water use and emissions, a unit commitment and dispatch power market simulation model is modified to evaluate the production of environmental externalities from power production. Scenarios are developed to apply a set of fees for cooling water, carbon dioxide, nitrous oxide and sulfur oxide emissions, respectively. Trade-offs between environmental performance, overall generation costs, and shifts in the power plants dispatched to meet demand are quantified for each power market simulation. The results from this study will provide insight into the development of a novel market-based framework that modifies the optimization algorithms governing the dispatching of electricity onto the grid in efforts to achieve cost-effective improvements in its environmental performance without the need for new infrastructure investments.

[Contrast-enhanced ultrasound (CEUS) and image fusion for procedures of liver interventions].

PubMed

Jung, E M; Clevert, D A

2018-06-01

Contrast-enhanced ultrasound (CEUS) is becoming increasingly important for the detection and characterization of malignant liver lesions and allows percutaneous treatment when surgery is not possible. Contrast-enhanced ultrasound image fusion with computed tomography (CT) and magnetic resonance imaging (MRI) opens up further options for the targeted investigation of a modified tumor treatment. Ultrasound image fusion offers the potential for real-time imaging and can be combined with other cross-sectional imaging techniques as well as CEUS. With the implementation of ultrasound contrast agents and image fusion, ultrasound has been improved in the detection and characterization of liver lesions in comparison to other cross-sectional imaging techniques. In addition, this method can also be used for intervention procedures. The success rate of fusion-guided biopsies or CEUS-guided tumor ablation lies between 80 and 100% in the literature. Ultrasound-guided image fusion using CT or MRI data, in combination with CEUS, can facilitate diagnosis and therapy follow-up after liver interventions. In addition to the primary applications of image fusion in the diagnosis and treatment of liver lesions, further useful indications can be integrated into daily work. These include, for example, intraoperative and vascular applications as well applications in other organ systems.

Brightness-preserving fuzzy contrast enhancement scheme for the detection and classification of diabetic retinopathy disease.

PubMed

Datta, Niladri Sekhar; Dutta, Himadri Sekhar; Majumder, Koushik

2016-01-01

The contrast enhancement of retinal image plays a vital role for the detection of microaneurysms (MAs), which are an early sign of diabetic retinopathy disease. A retinal image contrast enhancement method has been presented to improve the MA detection technique. The success rate on low-contrast noisy retinal image analysis shows the importance of the proposed method. Overall, 587 retinal input images are tested for performance analysis. The average sensitivity and specificity are obtained as 95.94% and 99.21%, respectively. The area under curve is found as 0.932 for the receiver operating characteristics analysis. The classifications of diabetic retinopathy disease are also performed here. The experimental results show that the overall MA detection method performs better than the current state-of-the-art MA detection algorithms.

Correlation of Tumor Immunohistochemistry with Dynamic Contrast-Enhanced and DSC-MRI Parameters in Patients with Gliomas.

PubMed

Nguyen, T B; Cron, G O; Bezzina, K; Perdrizet, K; Torres, C H; Chakraborty, S; Woulfe, J; Jansen, G H; Thornhill, R E; Zanette, B; Cameron, I G

2016-12-01

Tumor CBV is a prognostic and predictive marker for patients with gliomas. Tumor CBV can be measured noninvasively with different MR imaging techniques; however, it is not clear which of these techniques most closely reflects histologically-measured tumor CBV. Our aim was to investigate the correlations between dynamic contrast-enhanced and DSC-MR imaging parameters and immunohistochemistry in patients with gliomas. Forty-three patients with a new diagnosis of glioma underwent a preoperative MR imaging examination with dynamic contrast-enhanced and DSC sequences. Unnormalized and normalized cerebral blood volume was obtained from DSC MR imaging. Two sets of plasma volume and volume transfer constant maps were obtained from dynamic contrast-enhanced MR imaging. Plasma volume obtained from the phase-derived vascular input function and bookend T1 mapping (Vp_Φ) and volume transfer constant obtained from phase-derived vascular input function and bookend T1 mapping (K trans _Φ) were determined. Plasma volume obtained from magnitude-derived vascular input function (Vp_SI) and volume transfer constant obtained from magnitude-derived vascular input function (K trans _SI) were acquired, without T1 mapping. Using CD34 staining, we measured microvessel density and microvessel area within 3 representative areas of the resected tumor specimen. The Mann-Whitney U test was used to test for differences according to grade and degree of enhancement. The Spearman correlation was performed to determine the relationship between dynamic contrast-enhanced and DSC parameters and histopathologic measurements. Microvessel area, microvessel density, dynamic contrast-enhanced, and DSC-MR imaging parameters varied according to the grade and degree of enhancement (P < .05). A strong correlation was found between microvessel area and Vp_Φ and between microvessel area and unnormalized blood volume (r s ≥ 0.61). A moderate correlation was found between microvessel area and normalized blood

Assessment of Bowel Wall Enhancement for the Diagnosis of Intestinal Ischemia in Patients with Small Bowel Obstruction: Value of Adding Unenhanced CT to Contrast-enhanced CT.

PubMed

Chuong, Anh Minh; Corno, Lucie; Beaussier, Hélène; Boulay-Coletta, Isabelle; Millet, Ingrid; Hodel, Jérôme; Taourel, Patrice; Chatellier, Gilles; Zins, Marc

2016-07-01

Purpose To determine whether adding unenhanced computed tomography (CT) to contrast material-enhanced CT improves the diagnostic performance of decreased bowel wall enhancement as a sign of ischemia complicating mechanical small bowel obstruction (SBO). Materials and Methods This retrospective study was approved by the institutional review board, which waived the requirement for informed consent. Two gastrointestinal radiologists independently performed retrospective assessments of 164 unenhanced and contrast-enhanced CT studies from 158 consecutive patients (mean age, 71.2 years) with mechanical SBO. The reference standard was the intraoperative and/or histologic diagnosis (in 80 cases) or results from clinical follow-up in patients who did not undergo surgery (84 cases). Decreased bowel wall enhancement was evaluated with contrast-enhanced images then and both unenhanced and contrast-enhanced images 1 month later. Diagnostic performance of decreased bowel wall enhancement and confidence in the diagnosis were compared between the two readings by using McNemar and Wilcoxon signed rank tests. Interobserver agreement was assessed by using κ statistics and compared with bootstrapping. Results Ischemia was diagnosed in 41 of 164 (25%) episodes of SBO. For both observers, adding unenhanced images improved decreased bowel wall enhancement sensitivity (observer 1: 46.3% [19 of 41] vs 65.8% [27 of 41], P = .02; observer 2: 56.1% [23 of 41] vs 63.4% [26 of 41], P = .45), Youden index (from 0.41 to 0.58 for observer 1 and from 0.42 to 0.61 for observer 2), and confidence score (P < .001 for both). Specificity significantly increased for observer 2 (84.5% [104 of 123] vs 94.3% [116 of 123], P = .002), and interobserver agreement significantly increased, from moderate (κ = 0.48) to excellent (κ = 0.89; P < .0001). Conclusion Adding unenhanced CT to contrast-enhanced CT improved the sensitivity, diagnostic confidence, and interobserver agreement of the diagnosis of ischemia

Influence of Contrast Media on Bone Mineral Density (BMD) Measurements from Routine Contrast-Enhanced MDCT Datasets using a Phantom-less BMD Measurement Tool.

PubMed

Toelly, Andrea; Bardach, Constanze; Weber, Michael; Gong, Rui; Lai, Yanbo; Wang, Pei; Guo, Yulin; Kirschke, Jan; Baum, Thomas; Gruber, Michael

2017-06-01

Aim  To evaluate the differences in phantom-less bone mineral density (BMD) measurements in contrast-enhanced routine MDCT scans at different contrast phases, and to develop an algorithm for calculating a reliable BMD value. Materials and Methods  112 postmenopausal women from the age of 40 to 77 years (mean age: 57.31 years; SD 9.61) who underwent a clinically indicated MDCT scan, consisting of an unenhanced, an arterial, and a venous phase, were included. A retrospective analysis of the BMD values of the Th12 to L4 vertebrae in each phase was performed using a commercially available phantom-less measurement tool. Results  The mean BMD value in the unenhanced MDCT scans was 79.76 mg/cm³ (SD 31.20), in the arterial phase it was 85.09 mg/cm³ (SD 31.61), and in the venous phase it was 86.18 mg/cm³ (SD 31.30). A significant difference (p < 0.001) was found between BMD values on unenhanced and contrast-enhanced MDCT scans. There was no significant difference between BMD values in the arterial and venous phases (p = 0.228). The following conversion formulas were calculated using linear regression: unenhanced BMD = -2.287 + 0.964 * [arterial BMD value] and -4.517 + 0.978 * [venous BMD value]. The intrarater agreement of BMD measurements was calculated with an intraclass correlation (ICC) of 0.984 and the interobserver reliability was calculated with an ICC of 0.991. Conclusion  Phantom-less BMD measurements in contrast-enhanced MDCT scans result in increased mean BMD values, but, with the formulas applied in our study, a reliable BMD value can be calculated. However, the mean BMD values did not differ significantly between the arterial and venous phases. Key points   · BMD can be assessed on routine CT scans using a phantom-less tool.. · i. v. contrast agent significantly elevates BMD values measured on routine CT scans.. · BMD values measured in the arterial and venous phase did not differ significantly.. · Conversion

Optical clearing of skin enhanced with hyaluronic acid for increased contrast of optoacoustic imaging

NASA Astrophysics Data System (ADS)

Liopo, Anton; Su, Richard; Tsyboulski, Dmitri A.; Oraevsky, Alexander A.

2016-08-01

Enhanced delivery of optical clearing agents (OCA) through skin may improve sensitivity of optical and optoacoustic (OA) methods of imaging, sensing, and monitoring. This report describes a two-step method for enhancement of light penetration through skin. Here, we demonstrate that topical application of hyaluronic acid (HA) improves skin penetration of hydrophilic and lipophilic OCA and thus enhances their performance. We examined the OC effect of 100% polyethylene and polypropylene glycols (PPGs) and their mixture after pretreatment by HA, and demonstrated significant increase in efficiency of light penetration through skin. Increased light transmission resulted in a significant increase of OA image contrast in vitro. Topical pretreatment of skin for about 30 min with 0.5% HA in aqueous solution offers effective delivery of low molecular weight OCA such as a mixture of PPG-425 and polyethylene glycol (PEG)-400. The developed approach of pretreatment by HA prior to application of clearing agents (PEG and PPG) resulted in a ˜47-fold increase in transmission of red and near-infrared light and significantly enhanced contrast of OA images.

Contrast-enhanced magnetic resonance imaging of pulmonary lesions: description of a technique aiming clinical practice.

PubMed

Koenigkam-Santos, Marcel; Optazaite, Elzbieta; Sommer, Gregor; Safi, Seyer; Heussel, Claus Peter; Kauczor, Hans-Ulrich; Puderbach, Michael

2015-01-01

To propose a technique for evaluation of pulmonary lesions using contrast-enhanced MRI; to assess morphological patterns of enhancement and correlate quantitative analysis with histopathology. Thirty-six patients were prospectively studied. Volumetric-interpolated T1W images were obtained during consecutive breath holds after bolus triggered contrast injection. Volume coverage of first three acquisitions was limited (higher temporal resolution) and last acquisition obtained at 4th min. Two radiologists individually evaluated the patterns of enhancement. Region-of-interest-based signal intensity (SI)-time curves were created to assess quantitative parameters. Readers agreed moderately to substantially concerning lesions' enhancement pattern. SI-time curves could be created for all lesions. In comparison to benign, malignant lesions showed higher values of maximum enhancement, early peak, slope and 4th min enhancement. Early peak >15% showed 100% sensitivity to detect malignancy, maximum enhancement >40% showed 100% specificity. The proposed technique is robust, simple to perform and can be applied in clinical scenario. It allows visual evaluation of enhancement pattern/progression together with creation of SI-time curves and assessment of derived quantitative parameters. Perfusion analysis was highly sensitive to detect malignancy, in accordance to what is recommended by most recent guidelines on imaging evaluation of pulmonary lesions. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Optimal MRI sequence for identifying occlusion location in acute stroke: which value of time-resolved contrast-enhanced MRA?

PubMed

Le Bras, A; Raoult, H; Ferré, J-C; Ronzière, T; Gauvrit, J-Y

2015-06-01

Identifying occlusion location is crucial for determining the optimal therapeutic strategy during the acute phase of ischemic stroke. The purpose of this study was to assess the diagnostic efficacy of MR imaging, including conventional sequences plus time-resolved contrast-enhanced MRA in comparison with DSA for identifying arterial occlusion location. Thirty-two patients with 34 occlusion levels referred for thrombectomy during acute cerebral stroke events were consecutively included from August 2010 to December 2012. Before thrombectomy, we performed 3T MR imaging, including conventional 3D-TOF and gradient-echo T2 sequences, along with time-resolved contrast-enhanced MRA of the extra- and intracranial arteries. The 3D-TOF, gradient-echo T2, and time-resolved contrast-enhanced MRA results were consensually assessed by 2 neuroradiologists and compared with prethrombectomy DSA results in terms of occlusion location. The Wilcoxon test was used for statistical analysis to compare MR imaging sequences with DSA, and the κ coefficient was used to determine intermodality agreement. The occlusion level on the 3D-TOF and gradient-echo T2 images differed significantly from that of DSA (P < .001 and P = .002, respectively), while no significant difference was observed between DSA and time-resolved contrast-enhanced MRA (P = .125). κ coefficients for intermodality agreement with DSA (95% CI, percentage agreement) were 0.43 (0.3%-0.6; 62%), 0.32 (0.2%-0.5; 56%), and 0.81 (0.6%-1.0; 88%) for 3D-TOF, gradient-echo T2, and time-resolved contrast-enhanced MRA, respectively. The time-resolved contrast-enhanced MRA sequence proved reliable for identifying occlusion location in acute stroke with performance superior to that of 3D-TOF and gradient-echo T2 sequences. © 2015 by American Journal of Neuroradiology.

Newly Diagnosed Breast Cancer: Comparison of Contrast-enhanced Spectral Mammography and Breast MR Imaging in the Evaluation of Extent of Disease.

PubMed

Lee-Felker, Stephanie A; Tekchandani, Leena; Thomas, Mariam; Gupta, Esha; Andrews-Tang, Denise; Roth, Antoinette; Sayre, James; Rahbar, Guita

2017-11-01

Purpose To compare the diagnostic performances of contrast material-enhanced spectral mammography and breast magnetic resonance (MR) imaging in the detection of index and secondary cancers in women with newly diagnosed breast cancer by using histologic or imaging follow-up as the standard of reference. Materials and Methods This institutional review board-approved, HIPAA-compliant, retrospective study included 52 women who underwent breast MR imaging and contrast-enhanced spectral mammography for newly diagnosed unilateral breast cancer between March 2014 and October 2015. Of those 52 patients, 46 were referred for contrast-enhanced spectral mammography and targeted ultrasonography because they had additional suspicious lesions at MR imaging. In six of the 52 patients, breast cancer had been diagnosed at an outside institution. These patients were referred for contrast-enhanced spectral mammography and targeted US as part of diagnostic imaging. Images from contrast-enhanced spectral mammography were analyzed by two fellowship-trained breast imagers with 2.5 years of experience with contrast-enhanced spectral mammography. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value were calculated for both imaging modalities and compared by using the Bennett statistic. Results Fifty-two women with 120 breast lesions were included for analysis (mean age, 50 years; range, 29-73 years). Contrast-enhanced spectral mammography had similar sensitivity to MR imaging (94% [66 of 70 lesions] vs 99% [69 of 70 lesions]), a significantly higher PPV than MR imaging (93% [66 of 71 lesions] vs 60% [69 of 115 lesions]), and fewer false-positive findings than MR imaging (five vs 45) (P < .001 for all results). In addition, contrast-enhanced spectral mammography depicted 11 of the 11 secondary cancers (100%) and MR imaging depicted 10 (91%). Conclusion Contrast-enhanced spectral mammography is potentially as sensitive as MR imaging in the evaluation of

Discrimination Training of Phonemic Contrasts Enhances Phonological Processing in Mainstream School Children

ERIC Educational Resources Information Center

Moore, D.R.; Rosenberg, J.F.; Coleman, J.S.

2005-01-01

Auditory perceptual learning has been proposed as effective for remediating impaired language and for enhancing normal language development. We examined the effect of phonemic contrast discrimination training on the discrimination of whole words and on phonological awareness in 8- to 10-year-old mainstream school children. Eleven phonemic contrast…

SU-F-J-71: Improving CT Quality for Radiation Therapy Planning and Delivery Guidance Using a Non-Linear Contrast Enhancement Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noid, G; Tai, A; Li, X

2016-06-15

Purpose: Advanced image post-processing techniques which enhance soft-tissue contrast in CT have not been widely employed for RT planning or delivery guidance. The purpose of this work is to assess the soft-tissue contrast enhancement from non-linear contrast enhancing filters and its impact in RT. The contrast enhancement reduces patient alignment uncertainties. Methods: Non-linear contrast enhancing methods, such as Best Contrast (Siemens), amplify small differences in X-ray attenuation between two adjacent structure without significantly increasing noise. Best Contrast (BC) separates a CT into two frequency bands. The low frequency band is modified by a non-linear scaling function before recombination with themore » high frequency band. CT data collected using a CT-on-rails (Definition AS Open, Siemens) during daily CT-guided RT for 6 prostate cancer patients and an image quality phantom (The Phantom Laboratory) were analyzed. Images acquired with a standard protocol (120 kVp, 0.6 pitch, 18 mGy CTDIvol) were processed before comparison to the unaltered images. Contrast and noise were measured in the the phantom. Inter-observer variation was assessed by placing prostate contours on the 12 CT study sets, 6 enhanced and 6 unaltered, in a blinded study involving 8 observers. Results: The phantom data demonstrate that BC increased the contrast between the 1.0% supra-slice element and the background substrate by 46.5 HU while noise increased by only 2.3 HU. Thus the contrast to noise ratio increased from 1.28 to 6.71. Furthermore, the variation in centroid position of the prostate contours was decreased from 1.3±0.4 mm to 0.8±0.3 mm. Thus the CTV-to-PTV margin was reduced by 1.1 mm. The uncertainty in delineation of the prostate/rectum edge decreased by 0.5 mm. Conclusion: As demonstrated in phantom and patient scans the BC filter accentuates soft-tissue contrast. This enhancement leads to reduced inter-observer variation, which should improve RT planning and

Characterization of Metabolic, Diffusion, and Perfusion Properties in GBM: Contrast-Enhancing versus Non-Enhancing Tumor.

PubMed

Autry, Adam; Phillips, Joanna J; Maleschlijski, Stojan; Roy, Ritu; Molinaro, Annette M; Chang, Susan M; Cha, Soonmee; Lupo, Janine M; Nelson, Sarah J

2017-12-01

Although the contrast-enhancing (CE) lesion on T 1 -weighted MR images is widely used as a surrogate for glioblastoma (GBM), there are also non-enhancing regions of infiltrative tumor within the T 2 -weighted lesion, which elude radiologic detection. Because non-enhancing GBM (Enh-) challenges clinical patient management as latent disease, this study sought to characterize ex vivo metabolic profiles from Enh- and CE GBM (Enh+) samples, alongside histological and in vivo MR parameters, to assist in defining criteria for estimating total tumor burden. Fifty-six patients with newly diagnosed GBM received a multi-parametric pre-surgical MR examination. Targets for obtaining image-guided tissue samples were defined based on in vivo parameters that were suspicious for tumor. The actual location from where tissue samples were obtained was recorded, and half of each sample was analyzed for histopathology while the other half was scanned using HR-MAS spectroscopy. The Enh+ and Enh- tumor samples demonstrated comparable mitotic activity, but also significant heterogeneity in microvascular morphology. Ex vivo spectroscopic parameters indicated similar levels of total choline and N-acetylaspartate between these contrast-based radiographic subtypes of GBM, and characteristic differences in the levels of myo-inositol, creatine/phosphocreatine, and phosphoethanolamine. Analysis of in vivo parameters at the sample locations were consistent with histological and ex vivo metabolic data. The similarity between ex vivo levels of choline and NAA, and between in vivo levels of choline, NAA and nADC in Enh+ and Enh- tumor, indicate that these parameters can be used in defining non-invasive metrics of total tumor burden for patients with GBM. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Contrast enhancement of subcutaneous blood vessel images by means of visible and near-infrared hyper-spectral imaging

NASA Astrophysics Data System (ADS)

Katrašnik, Jaka; Bürmen, Miran; Pernuš, Franjo; Likar, Boštjan

2009-02-01

Visualization of subcutaneous veins is very difficult with the naked eye, but important for diagnosis of medical conditions and different medical procedures such as catheter insertion and blood withdrawal. Moreover, recent studies showed that the images of subcutaneous veins could be used for biometric identification. The majority of methods used for enhancing the contrast between the subcutaneous veins and surrounding tissue are based on simple imaging systems utilizing CMOS or CCD cameras with LED illumination capable of acquiring images from the near infrared spectral region, usually near 900 nm. However, such simplified imaging methods cannot exploit the full potential of the spectral information. In this paper, a new highly versatile method for enhancing the contrast of subcutaneous veins based on state-of-the-art high-resolution hyper-spectral imaging system utilizing the spectral region from 550 to 1700 nm is presented. First, a detailed analysis of the contrast between the subcutaneous veins and the surrounding tissue as a function of wavelength, for several different positions on the human arm, was performed in order to extract the spectral regions with the highest contrast. The highest contrast images were acquired at 1100 nm, however, combining the individual images from the extracted spectral regions by the proposed contrast enhancement method resulted in a single image with up to ten-fold better contrast. Therefore, the proposed method has proved to be a useful tool for visualization of subcutaneous veins.

Study of quality perception in medical images based on comparison of contrast enhancement techniques in mammographic images

NASA Astrophysics Data System (ADS)

Matheus, B.; Verçosa, L. B.; Barufaldi, B.; Schiabel, H.

2014-03-01

With the absolute prevalence of digital images in mammography several new tools became available for radiologist; such as CAD schemes, digital zoom and contrast alteration. This work focuses in contrast variation and how the radiologist reacts to these changes when asked to evaluated image quality. Three contrast enhancing techniques were used in this study: conventional equalization, CCB Correction [1] - a digitization correction - and value subtraction. A set of 100 images was used in tests from some available online mammographic databases. The tests consisted of the presentation of all four versions of an image (original plus the three contrast enhanced images) to the specialist, requested to rank each one from the best up to worst quality for diagnosis. Analysis of results has demonstrated that CCB Correction [1] produced better images in almost all cases. Equalization, which mathematically produces a better contrast, was considered the worst for mammography image quality enhancement in the majority of cases (69.7%). The value subtraction procedure produced images considered better than the original in 84% of cases. Tests indicate that, for the radiologist's perception, it seems more important to guaranty full visualization of nuances than a high contrast image. Another result observed is that the "ideal" scanner curve does not yield the best result for a mammographic image. The important contrast range is the middle of the histogram, where nodules and masses need to be seen and clearly distinguished.

An Algorithm of Image Heterogeneity with Contrast-Enhanced Ultrasound in Differential Diagnosis of Solid Thyroid Nodules.

PubMed

Jin, Lifang; Xu, Changsong; Xie, Xueqian; Li, Fan; Lv, Xiuhong; Du, Lianfang

2017-01-01

Enhancement heterogeneity on contrast-enhanced ultrasonography (CEUS) is used to differentiate between benign and malignant thyroid nodules. In this study, we used an algorithm to quantify enhancement heterogeneity of solid thyroid nodules on CEUS. The heterogeneity value (HV) is calculated as standard deviation/mean intensity × 100 (using Adobe Photoshop). The heterogeneity ratio (HR) is calculated as the ratio of the HV of the nodule to that of the surrounding parenchyma. Three phases-ascending, peak and descending phases-were studied. HV values at ascending (HV a ) and peak (HV p ) phases were significantly higher in malignant nodules than in benign nodules (95.57 ± 43.87 vs. 73.06 ± 44.04, p = 0.009, and 32.53 ± 10.73 vs. 26.44 ± 8.25, p = 0.002, respectively). HR a , HR p and HR d were significantly higher in malignant nodules than in benign nodules (1.93 ± 1.03 vs. 1.00 ± 0.47, p = 0.000, 1.43 ± 0.51 vs. 1.09 ± 0.28, p = 0.000, and 1.33 ± 0.40 vs. 1.08 ± 0.33, p = 0.001, respectively). HR a achieved optimal diagnostic performance on receiver operating characteristic curve analysis. The algorithm used for assessment of image heterogeneity on CEUS examination may be a useful adjunct to conventional ultrasound for differential diagnosis of solid thyroid nodules. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Contrast-enhanced spectral mammography with a photon-counting detector.

PubMed

Fredenberg, Erik; Hemmendorff, Magnus; Cederström, Björn; Aslund, Magnus; Danielsson, Mats

2010-05-01

Spectral imaging is a method in medical x-ray imaging to extract information about the object constituents by the material-specific energy dependence of x-ray attenuation. The authors have investigated a photon-counting spectral imaging system with two energy bins for contrast-enhanced mammography. System optimization and the potential benefit compared to conventional non-energy-resolved absorption imaging was studied. A framework for system characterization was set up that included quantum and anatomical noise and a theoretical model of the system was benchmarked to phantom measurements. Optimal combination of the energy-resolved images corresponded approximately to minimization of the anatomical noise, which is commonly referred to as energy subtraction. In that case, an ideal-observer detectability index could be improved close to 50% compared to absorption imaging in the phantom study. Optimization with respect to the signal-to-quantum-noise ratio, commonly referred to as energy weighting, yielded only a minute improvement. In a simulation of a clinically more realistic case, spectral imaging was predicted to perform approximately 30% better than absorption imaging for an average glandularity breast with an average level of anatomical noise. For dense breast tissue and a high level of anatomical noise, however, a rise in detectability by a factor of 6 was predicted. Another approximately 70%-90% improvement was found to be within reach for an optimized system. Contrast-enhanced spectral mammography is feasible and beneficial with the current system, and there is room for additional improvements. Inclusion of anatomical noise is essential for optimizing spectral imaging systems.

Local ablation therapy with contrast-enhanced ultrasonography for hepatocellular carcinoma: a practical review

PubMed Central

Kim, Tae Kyoung; Khalili, Korosh; Jang, Hyun-Jung

2015-01-01

A successful program for local ablation therapy for hepatocellular carcinoma (HCC) requires extensive imaging support for diagnosis and localization of HCC, imaging guidance for the ablation procedures, and post-treatment monitoring. Contrast-enhanced ultrasonography (CEUS) has several advantages over computed tomography/magnetic resonance imaging (CT/MRI), including real-time imaging capability, sensitive detection of arterial-phase hypervascularity and washout, no renal excretion, no ionizing radiation, repeatability, excellent patient compliance, and relatively low cost. CEUS is useful for image guidance for isoechoic lesions. While contrast-enhanced CT/MRI is the standard method for the diagnosis of HCC and post-ablation monitoring, CEUS is useful when CT/MRI findings are indeterminate or CT/MRI is contraindicated. This article provides a practical review of the role of CEUS in imaging algorithms for pre- and post-ablation therapy for HCC. PMID:26169081

Cuckoo search algorithm based satellite image contrast and brightness enhancement using DWT-SVD.

PubMed

Bhandari, A K; Soni, V; Kumar, A; Singh, G K

2014-07-01

This paper presents a new contrast enhancement approach which is based on Cuckoo Search (CS) algorithm and DWT-SVD for quality improvement of the low contrast satellite images. The input image is decomposed into the four frequency subbands through Discrete Wavelet Transform (DWT), and CS algorithm used to optimize each subband of DWT and then obtains the singular value matrix of the low-low thresholded subband image and finally, it reconstructs the enhanced image by applying IDWT. The singular value matrix employed intensity information of the particular image, and any modification in the singular values changes the intensity of the given image. The experimental results show superiority of the proposed method performance in terms of PSNR, MSE, Mean and Standard Deviation over conventional and state-of-the-art techniques. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Clinical performance of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced pediatric abdominal MR angiography.

PubMed

Zhang, Tao; Yousaf, Ufra; Hsiao, Albert; Cheng, Joseph Y; Alley, Marcus T; Lustig, Michael; Pauly, John M; Vasanawala, Shreyas S

2015-10-01

Pediatric contrast-enhanced MR angiography is often limited by respiration, other patient motion and compromised spatiotemporal resolution. To determine the reliability of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced MR angiography method for depicting abdominal arterial anatomy in young children. With IRB approval and informed consent, we retrospectively identified 27 consecutive children (16 males and 11 females; mean age: 3.8 years, range: 14 days to 8.4 years) referred for contrast-enhanced MR angiography at our institution, who had undergone free-breathing spatiotemporally accelerated time-resolved contrast-enhanced MR angiography studies. A radio-frequency-spoiled gradient echo sequence with Cartesian variable density k-space sampling and radial view ordering, intrinsic motion navigation and intermittent fat suppression was developed. Images were reconstructed with soft-gated parallel imaging locally low-rank method to achieve both motion correction and high spatiotemporal resolution. Quality of delineation of 13 abdominal arteries in the reconstructed images was assessed independently by two radiologists on a five-point scale. Ninety-five percent confidence intervals of the proportion of diagnostically adequate cases were calculated. Interobserver agreements were also analyzed. Eleven out of 13 arteries achieved acceptable image quality (mean score range: 3.9-5.0) for both readers. Fair to substantial interobserver agreement was reached on nine arteries. Free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced MR angiography frequently yields diagnostic image quality for most abdominal arteries in young children.

SU-E-J-187: Individually Optimized Contrast-Enhancement 4D-CT for Pancreatic Adenocarcinoma in Radiotherapy Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xue, M; Patel, K; Regine, W

2014-06-01

Purpose: To study the feasibility of individually optimized contrastenhancement (CE) 4D-CT for pancreatic adenocarcinoma (PDA) in radiotherapy simulation. To evaluate the image quality and contrast enhancement of tumor in the CE 4D-CT, compared to the clinical standard of CE 3D-CT and 4D-CT. Methods: In this IRB-approved study, each of the 7 PDA patients enrolled underwent 3 CT scans: a free-breathing 3D-CT with contrast (CE 3D-CT) followed by a 4D-CT without contrast (4D-CT) in the first study session, and a 4D-CT with individually synchronized contrast injection (CE 4D-CT) in the second study session. In CE 4D-CT, the time of full contrastmore » injection was determined based on the time of peak enhancement for the test injection, injection rate, table speed, and longitudinal location and span of the pancreatic region. Physicians contoured both the tumor (T) and the normal pancreatic parenchyma (P) on the three CTs (end-of-exhalation for 4D-CT). The contrast between the tumor and normal pancreatic tissue was computed as the difference of the mean enhancement level of three 1 cm3 regions of interests in T and P, respectively. Wilcoxon rank sum test was used to statistically compare the scores and contrasts. Results: In qualitative evaluations, both CE 3D-CT and CE 4D-CT scored significantly better than 4D-CT (4.0 and 3.6 vs. 2.6). There was no significant difference between CE 3D-CT and CE 4D-CT. In quantitative evaluations, the contrasts between the tumor and the normal pancreatic parenchyma were 0.6±23.4, −2.1±8.0, and −19.6±28.8 HU, in CE 3D-CT, 4D-CT, and CE 4D-CT, respectively. Although not statistically significant, CE 4D-CT achieved better contrast enhancement between the tumor and the normal pancreatic parenchyma than both CE 3D-CT and 4DCT. Conclusion: CE 4D-CT achieved equivalent image quality and better contrast enhancement between tumor and normal pancreatic parenchyma than the clinical standard of CE 3D-CT and 4D-CT. This study was supported

Dynamic Contrast-Enhanced Magnetic Resonance Imaging Reveals Stress-Induced Angiogenesis in MCF7 Human Breast Tumors

NASA Astrophysics Data System (ADS)

Furman-Haran, Edna; Margalit, Raanan; Grobgeld, Dov; Degani, Hadassa

1996-06-01

The mechanism of contrast enhancement of tumors using magnetic resonance imaging was investigated in MCF7 human breast cancer implanted in nude mice. Dynamic contrast-enhanced images recorded at high spatial resolution were analyzed by an image analysis method based on a physiological model, which included the blood circulation, the tumor, the remaining tissues, and clearance via the kidneys. This analysis enabled us to map in rapidly enhancing regions within the tumor, the capillary permeability factor (capillary permeability times surface area per voxel volume) and the fraction of leakage space. Correlation of these maps with T2-weighted spin echo images, with histopathology, and with immunohistochemical staining of endothelial cells demonstrated the presence of dense permeable microcapillaries in the tumor periphery and in intratumoral regions that surrounded necrotic loci. The high leakage from the intratumoral permeable capillaries indicated an induction of a specific angiogenic process associated with stress conditions that cause necrosis. This induction was augmented in tumors responding to tamoxifen treatment. Determination of the distribution and extent of this stress-induced angiogenic activity by contrast-enhanced MRI might be of diagnostic and of prognostic value.

Review of dynamic contrast-enhanced MRI: Technical aspects and applications in the musculoskeletal system.

PubMed

Sujlana, Parvinder; Skrok, Jan; Fayad, Laura M

2018-04-01

Although postcontrast imaging has been used for many years in musculoskeletal imaging, dynamic contrast enhanced (DCE) MRI is not routinely used in many centers around the world. Unlike conventional contrast-enhanced sequences, DCE-MRI allows the evaluation of the temporal pattern of enhancement in the musculoskeletal system, perhaps best known for its use in oncologic applications (such as differentiating benign from malignant tumors, evaluating for treatment response after neoadjuvant chemotherapy, and differentiating postsurgical changes from residual tumor). However, DCE-MRI can also be used to evaluate inflammatory processes such as Charcot foot and synovitis, and evaluate bone perfusion in entities like Legg Calve Perthes disease and arthritis. Finally, vascular abnormalities and associated complications may be better characterized with DCE-MRI than conventional imaging. The goal of this article is to review the applications and technical aspects of DCE-MRI in the musculoskeletal system. 5 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:875-890. © 2017 International Society for Magnetic Resonance in Medicine.

A Combined Pharmacokinetic and Radiologic Assessment of Dynamic Contrast-Enhanced Magnetic Resonance Imaging Predicts Response to Chemoradiation in Locally Advanced Cervical Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Semple, Scott; Harry, Vanessa N. MRCOG.; Parkin, David E.

2009-10-01

Purpose: To investigate the combination of pharmacokinetic and radiologic assessment of dynamic contrast-enhanced magnetic resonance imaging (MRI) as an early response indicator in women receiving chemoradiation for advanced cervical cancer. Methods and Materials: Twenty women with locally advanced cervical cancer were included in a prospective cohort study. Dynamic contrast-enhanced MRI was carried out before chemoradiation, after 2 weeks of therapy, and at the conclusion of therapy using a 1.5-T MRI scanner. Radiologic assessment of uptake parameters was obtained from resultant intensity curves. Pharmacokinetic analysis using a multicompartment model was also performed. General linear modeling was used to combine radiologic andmore » pharmacokinetic parameters and correlated with eventual response as determined by change in MRI tumor size and conventional clinical response. A subgroup of 11 women underwent repeat pretherapy MRI to test pharmacokinetic reproducibility. Results: Pretherapy radiologic parameters and pharmacokinetic K{sup trans} correlated with response (p < 0.01). General linear modeling demonstrated that a combination of radiologic and pharmacokinetic assessments before therapy was able to predict more than 88% of variance of response. Reproducibility of pharmacokinetic modeling was confirmed. Conclusions: A combination of radiologic assessment with pharmacokinetic modeling applied to dynamic MRI before the start of chemoradiation improves the predictive power of either by more than 20%. The potential improvements in therapy response prediction using this type of combined analysis of dynamic contrast-enhanced MRI may aid in the development of more individualized, effective therapy regimens for this patient group.« less

Bayesian Quantification of Contrast-Enhanced Ultrasound Images With Adaptive Inclusion of an Irreversible Component.

PubMed

Rizzo, Gaia; Tonietto, Matteo; Castellaro, Marco; Raffeiner, Bernd; Coran, Alessandro; Fiocco, Ugo; Stramare, Roberto; Grisan, Enrico

2017-04-01

Contrast Enhanced Ultrasound (CEUS) is a sensitive imaging technique to assess tissue vascularity and it can be particularly useful in early detection and grading of arthritis. In a recent study we have shown that a Gamma-variate can accurately quantify synovial perfusion and it is flexible enough to describe many heterogeneous patterns. However, in some cases the heterogeneity of the kinetics can be such that even the Gamma model does not properly describe the curve, with a high number of outliers. In this work we apply to CEUS data the single compartment recirculation model (SCR) which takes explicitly into account the trapping of the microbubbles contrast agent by adding to the single Gamma-variate model its integral. The SCR model, originally proposed for dynamic-susceptibility magnetic resonance imaging, is solved here at pixel level within a Bayesian framework using Variational Bayes (VB). We also include the automatic relevant determination (ARD) algorithm to automatically infer the model complexity (SCR vs. Gamma model) from the data. We demonstrate that the inclusion of trapping best describes the CEUS patterns in 50% of the pixels, with the other 50% best fitted by a single Gamma. Such results highlight the necessity of the use ARD, to automatically exclude the irreversible component where not supported by the data. VB with ARD returns precise estimates in the majority of the kinetics (88% of total percentage of pixels) in a limited computational time (on average, 3.6 min per subject). Moreover, the impact of the additional trapping component has been evaluated for the differentiation of rheumatoid and non-rheumatoid patients, by means of a support vector machine classifier with backward feature selection. The results show that the trapping parameter is always present in the selected feature set, and improves the classification.

TH-AB-207A-01: Contrast-Enhanced CT: Correlation of Radiation Dose and Biological Effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abadi, E; Sanders, J; Agasthya, G

2016-06-15

Purpose: The potential risk from CT is generally characterized in terms of radiation dose. The presence of iodinated-contrast medium increases radiation dose. However, it is unclear how much of this increase is biologically relevant. The purpose of this study was to establish the contribution of dose increase from iodine to biological effect. Methods: Radiation organ dose was estimated in 58 human (XCAT) phantoms “undergoing” chest CT examination (120 kVp, 9 mGy CTDI) on a simulated CT system (Definition Flash, Siemens) with and without iodinated-contrast agent (62.5 mL of iodine per subject). The dose without and with the presence of iodinemore » was compared to the increase in foci per cell (a surrogate of DNA damage) measured before and after similar CT exams without and with contrast agent (Piechowiak et al. 2015). The data were analyzed to ascertain how the enhancement in biological effect in contrast-enhanced CTs correlated with the increase in dose due to the presence of iodine. Results: The presence of iodinated-contrast in CT increased the organ doses by 2% to 50% on average. Typical values were heart (50%±7%), kidney (19%±7%), and liver (2%±3%). The corresponding increase in the average foci per cell was 107%±19%, indicating biological effect of iodine was greater than what would be anticipated from the iodine-initiated increase in radiation dose alone. Conclusion: Mean foci per cell and organ dose both increase in the presence of contrast agent. The former, however, is at least twice as large as the latter, indicating that iodine contributes to an increase in the probability of DNA damage not only as a consequence of increased x-ray energy deposition but also from other mechanisms. Hence iodine radiation dose, while relevant to be included in estimating the risk associated with contrast-enhanced CT, still can underestimate the biological effects.« less

A Simulation Tool for Dynamic Contrast Enhanced MRI

PubMed Central

Mauconduit, Franck; Christen, Thomas; Barbier, Emmanuel Luc

2013-01-01

The quantification of bolus-tracking MRI techniques remains challenging. The acquisition usually relies on one contrast and the analysis on a simplified model of the various phenomena that arise within a voxel, leading to inaccurate perfusion estimates. To evaluate how simplifications in the interstitial model impact perfusion estimates, we propose a numerical tool to simulate the MR signal provided by a dynamic contrast enhanced (DCE) MRI experiment. Our model encompasses the intrinsic and relaxations, the magnetic field perturbations induced by susceptibility interfaces (vessels and cells), the diffusion of the water protons, the blood flow, the permeability of the vessel wall to the the contrast agent (CA) and the constrained diffusion of the CA within the voxel. The blood compartment is modeled as a uniform compartment. The different blocks of the simulation are validated and compared to classical models. The impact of the CA diffusivity on the permeability and blood volume estimates is evaluated. Simulations demonstrate that the CA diffusivity slightly impacts the permeability estimates ( for classical blood flow and CA diffusion). The effect of long echo times is investigated. Simulations show that DCE-MRI performed with an echo time may already lead to significant underestimation of the blood volume (up to 30% lower for brain tumor permeability values). The potential and the versatility of the proposed implementation are evaluated by running the simulation with realistic vascular geometry obtained from two photons microscopy and with impermeable cells in the extravascular environment. In conclusion, the proposed simulation tool describes DCE-MRI experiments and may be used to evaluate and optimize acquisition and processing strategies. PMID:23516414

Improving the quantification of contrast enhanced ultrasound using a Bayesian approach

NASA Astrophysics Data System (ADS)

Rizzo, Gaia; Tonietto, Matteo; Castellaro, Marco; Raffeiner, Bernd; Coran, Alessandro; Fiocco, Ugo; Stramare, Roberto; Grisan, Enrico

2017-03-01

Contrast Enhanced Ultrasound (CEUS) is a sensitive imaging technique to assess tissue vascularity, that can be useful in the quantification of different perfusion patterns. This can be particularly important in the early detection and staging of arthritis. In a recent study we have shown that a Gamma-variate can accurately quantify synovial perfusion and it is flexible enough to describe many heterogeneous patterns. Moreover, we have shown that through a pixel-by-pixel analysis the quantitative information gathered characterizes more effectively the perfusion. However, the SNR ratio of the data and the nonlinearity of the model makes the parameter estimation difficult. Using classical non-linear-leastsquares (NLLS) approach the number of unreliable estimates (those with an asymptotic coefficient of variation greater than a user-defined threshold) is significant, thus affecting the overall description of the perfusion kinetics and of its heterogeneity. In this work we propose to solve the parameter estimation at the pixel level within a Bayesian framework using Variational Bayes (VB), and an automatic and data-driven prior initialization. When evaluating the pixels for which both VB and NLLS provided reliable estimates, we demonstrated that the parameter values provided by the two methods are well correlated (Pearson's correlation between 0.85 and 0.99). Moreover, the mean number of unreliable pixels drastically reduces from 54% (NLLS) to 26% (VB), without increasing the computational time (0.05 s/pixel for NLLS and 0.07 s/pixel for VB). When considering the efficiency of the algorithms as computational time per reliable estimate, VB outperforms NLLS (0.11 versus 0.25 seconds per reliable estimate respectively).

Individually optimized contrast-enhanced 4D-CT for radiotherapy simulation in pancreatic ductal adenocarcinoma

PubMed Central

Xue, Ming; Lane, Barton F.; Kang, Min Kyu; Patel, Kruti; Regine, William F.; Klahr, Paul; Wang, Jiahui; Chen, Shifeng; D’Souza, Warren; Lu, Wei

2016-01-01

Purpose: To develop an individually optimized contrast-enhanced (CE) 4D-computed tomography (CT) for radiotherapy simulation in pancreatic ductal adenocarcinomas (PDA). Methods: Ten PDA patients were enrolled. Each underwent three CT scans: a 4D-CT immediately following a CE 3D-CT and an individually optimized CE 4D-CT using test injection. Three physicians contoured the tumor and pancreatic tissues. Image quality scores, tumor volume, motion, tumor-to-pancreas contrast, and contrast-to-noise ratio (CNR) were compared in the three CTs. Interobserver variations were also evaluated in contouring the tumor using simultaneous truth and performance level estimation. Results: Average image quality scores for CE 3D-CT and CE 4D-CT were comparable (4.0 and 3.8, respectively; P = 0.082), and both were significantly better than that for 4D-CT (2.6, P < 0.001). Tumor-to-pancreas contrast results were comparable in CE 3D-CT and CE 4D-CT (15.5 and 16.7 Hounsfield units (HU), respectively; P = 0.21), and the latter was significantly higher than in 4D-CT (9.2 HU, P = 0.001). Image noise in CE 3D-CT (12.5 HU) was significantly lower than in CE 4D-CT (22.1 HU, P = 0.013) and 4D-CT (19.4 HU, P = 0.009). CNRs were comparable in CE 3D-CT and CE 4D-CT (1.4 and 0.8, respectively; P = 0.42), and both were significantly better in 4D-CT (0.6, P = 0.008 and 0.014). Mean tumor volumes were significantly smaller in CE 3D-CT (29.8 cm3, P = 0.03) and CE 4D-CT (22.8 cm3, P = 0.01) than in 4D-CT (42.0 cm3). Mean tumor motion was comparable in 4D-CT and CE 4D-CT (7.2 and 6.2 mm, P = 0.17). Interobserver variations were comparable in CE 3D-CT and CE 4D-CT (Jaccard index 66.0% and 61.9%, respectively) and were worse for 4D-CT (55.6%) than CE 3D-CT. Conclusions: CE 4D-CT demonstrated characteristics comparable to CE 3D-CT, with high potential for simultaneously delineating the tumor and quantifying tumor motion with a single scan. PMID:27782710

Maximum Entropy Approach in Dynamic Contrast-Enhanced Magnetic Resonance Imaging.

PubMed

Farsani, Zahra Amini; Schmid, Volker J

2017-01-01

In the estimation of physiological kinetic parameters from Dynamic Contrast-Enhanced Magnetic Resonance Imaging (DCE-MRI) data, the determination of the arterial input function (AIF) plays a key role. This paper proposes a Bayesian method to estimate the physiological parameters of DCE-MRI along with the AIF in situations, where no measurement of the AIF is available. In the proposed algorithm, the maximum entropy method (MEM) is combined with the maximum a posterior approach (MAP). To this end, MEM is used to specify a prior probability distribution of the unknown AIF. The ability of this method to estimate the AIF is validated using the Kullback-Leibler divergence. Subsequently, the kinetic parameters can be estimated with MAP. The proposed algorithm is evaluated with a data set from a breast cancer MRI study. The application shows that the AIF can reliably be determined from the DCE-MRI data using MEM. Kinetic parameters can be estimated subsequently. The maximum entropy method is a powerful tool to reconstructing images from many types of data. This method is useful for generating the probability distribution based on given information. The proposed method gives an alternative way to assess the input function from the existing data. The proposed method allows a good fit of the data and therefore a better estimation of the kinetic parameters. In the end, this allows for a more reliable use of DCE-MRI. Schattauer GmbH.

Contrast enhancement in EIT imaging of the brain.

PubMed

Nissinen, A; Kaipio, J P; Vauhkonen, M; Kolehmainen, V

2016-01-01

We consider electrical impedance tomography (EIT) imaging of the brain. The brain is surrounded by the poorly conducting skull which has low conductivity compared to the brain. The skull layer causes a partial shielding effect which leads to weak sensitivity for the imaging of the brain tissue. In this paper we propose an approach based on the Bayesian approximation error approach, to enhance the contrast in brain imaging. With this approach, both the (uninteresting) geometry and the conductivity of the skull are embedded in the approximation error statistics, which leads to a computationally efficient algorithm that is able to detect features such as internal haemorrhage with significantly increased sensitivity and specificity. We evaluate the approach with simulations and phantom data.

Relapses in three patients with Takayasu arteritis under tocilizumab treatment detected by contrast enhanced ultrasound.

PubMed

Czihal, Michael; Lottspeich, Christian; Schröttle, Angelika; Treitl, Karla Maria; Treitl, Marcus; Leipe, Jan; Schulze-Koops, Hendrik; Hoffmann, Ulrich; Dechant, Claudia

2018-02-01

Takayasu arteritis (TA) is a rare large vessel vasculitis, affecting the aorta and its major branches, typically in young women. In this case report, we present three cases of young women of Caucasian descent who experienced relapses while under treatment with the monoclonal humanized antibody to the interleukin 6 receptor, tocilizumab. Active vasculitic lesions of the supraaortic (common carotid and axillary) arteries were detected and characterized via high resolution contrast enhanced ultrasound. Based on these cases, we discuss the potential role of contrast enhanced ultrasound in the diagnosis and follow-up of TA as well as the current data on the efficacy of tocilizumab in the treatment of TA.

[Value of contrast-enhanced ultrasound (CEUS) in the differential diagnosis between benign and malignant renal neoplasms].

PubMed

Zhang, Sheng; Wang, Xiao-qing; Xin, Xiao-jie; Xu, Yong

2013-05-01

To investigate the value of contrast enhanced ultrasound (CEUS) imaging in the differential diagnosis between benign and malignant renal neoplasms. Two hundred and forty-five cases of renal space-occupying lesions confirmed by biopsy or surgical pathology were included in this study. The CEUS features of the renal space-occupying lesions, i.e., the enhancement degree, homogeneity of enhancement, washing-in and washing-out time and enhancement pattern, were retrospectively analyzed. There were 210 cases of malignant renal tumors and 35 cases of benign lesions. The CEUS modes of the malignant renal tumors included "quick in and quick out" 82 cases, "quick in and slow out" 64 cases, "slow in and quick out" 18 cases and "slow in and slow out" 46 cases; good enhancement 150 cases (71.4%) and inhomogeneous enhancement 180 cases (85.7%).Both the contrast agent filling defect area and solid component enhancement of solid-cystic tumors were important features of malignant renal tumors. In the 35 cases of benign lesions,the CEUS modes included "quick in and quick out" 4 cases, "quick in and slow out" 8 cases, "slow in and quick out" 10 cases and "slow in and slow out" 13 cases. Most of the benign tumors showed low enhancement 51.4% (18/35) and inhomogeneous enhancement 54.3% (19/35). There were significant differences between the malignant and benign renal neoplasms in CEUS mode, degree of enhancement and homogeneity of enhancement (P < 0.05), and in time of increasing, peak time, peak intensity and peak intensity ratio (P < 0.05). The accuracy rates of contrast-enhanced ultrasound for diagnosis of benign and malignant tumors were 77.1% and 83.8%, respectively, while the two-dimensional ultrasound diagnosis of benign and malignant tumors were 68.6% and 76.7%, respectively, with a significant difference (P < 0.05). CEUS may provide more information to improve the diagnostic accuracy for renal neoplasms, and may play important role in differential diagnosis between benign and

WE-DE-207B-04: Quantitative Contrast-Enhanced Spectral Mammography Based On Photon-Counting Detectors: A Feasibility Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, H; Zhou, B; Beidokhti, D

Purpose: To investigate the feasibility of accurate quantification of iodine mass thickness in contrast-enhanced spectral mammography. Methods: Experimental phantom studies were performed on a spectral mammography system based on Si strip photon-counting detectors. Dual-energy images were acquired using 40 kVp and a splitting energy of 34 keV with 3 mm Al pre-filtration. The initial calibration was done with glandular and adipose tissue equivalent phantoms of uniform thicknesses and iodine disk phantoms of various concentrations. A secondary calibration was carried out using the iodine signal obtained from the dual-energy decomposed images and the known background phantom thicknesses and densities. The iodinemore » signal quantification method was validated using phantoms composed of a mixture of glandular and adipose materials, for various breast thicknesses and densities. Finally, the traditional dual-energy weighted subtraction method was also studied as a comparison. The measured iodine signal from both methods was compared to the known iodine concentrations of the disk phantoms to characterize the quantification accuracy. Results: There was good agreement between the iodine mass thicknesses measured using the proposed method and the known values. The root-mean-square (RMS) error was estimated to be 0.2 mg/cm2. The traditional weighted subtraction method also predicted a linear correlation between the measured signal and the known iodine mass thickness. However, the correlation slope and offset values were strongly dependent on the total breast thickness and density. Conclusion: The results of the current study suggest that iodine mass thickness can be accurately quantified with contrast-enhanced spectral mammography. The quantitative information can potentially improve the differentiation between benign and malignant legions. Grant funding from Philips Medical Systems.« less

An enhanced feature set for pattern recognition based contrast enhancement of contact-less captured latent fingerprints in digitized crime scene forensics

NASA Astrophysics Data System (ADS)

Hildebrandt, Mario; Kiltz, Stefan; Dittmann, Jana; Vielhauer, Claus

2014-02-01

In crime scene forensics latent fingerprints are found on various substrates. Nowadays primarily physical or chemical preprocessing techniques are applied for enhancing the visibility of the fingerprint trace. In order to avoid altering the trace it has been shown that contact-less sensors offer a non-destructive acquisition approach. Here, the exploitation of fingerprint or substrate properties and the utilization of signal processing techniques are an essential requirement to enhance the fingerprint visibility. However, especially the optimal sensory is often substrate-dependent. An enhanced generic pattern recognition based contrast enhancement approach for scans of a chromatic white light sensor is introduced in Hildebrandt et al.1 using statistical, structural and Benford's law2 features for blocks of 50 micron. This approach achieves very good results for latent fingerprints on cooperative, non-textured, smooth substrates. However, on textured and structured substrates the error rates are very high and the approach thus unsuitable for forensic use cases. We propose the extension of the feature set with semantic features derived from known Gabor filter based exemplar fingerprint enhancement techniques by suggesting an Epsilon-neighborhood of each block in order to achieve an improved accuracy (called fingerprint ridge orientation semantics). Furthermore, we use rotation invariant Hu moments as an extension of the structural features and two additional preprocessing methods (separate X- and Y Sobel operators). This results in a 408-dimensional feature space. In our experiments we investigate and report the recognition accuracy for eight substrates, each with ten latent fingerprints: white furniture surface, veneered plywood, brushed stainless steel, aluminum foil, "Golden-Oak" veneer, non-metallic matte car body finish, metallic car body finish and blued metal. In comparison to Hildebrandt et al.,1 our evaluation shows a significant reduction of the error rates

Contrast enhanced ultrasound of renal masses. A reappraisal of EFSUMB recommendations and possible emerging applications.

PubMed

Sparchez, Zeno; Radu, Pompilia; Sparchez, Mihaela; Crisan, Nicolae; Kacso, Gabriel; Petrut, Bogdan

2015-06-01

The main imagistic method for characterization of renal lesions is contrast enhanced computed tomography (CECT). Disadvantages of CECT are a contrast-induced nephropathy in patients with renal impairment, allergic reactions and high costs. Contrast-enhanced ultrasound (CEUS) evaluation of hepatic and non-hepatic lesions is a relatively new, but increasingly utilised, diagnostic method. In 2011 the European Federation of Societies of Ultrasound in Medicine and Biology (EFSUMB) updated the Guidelines and Recommendations on the Clinical Practice of CEUS and included in the recommendation the renal pathology. However, there are several possible new indications that have not been discussed (pyelocaliceal masses and renal vein thrombosis) and several issues that remain controversial such as the differentiation of benign and malignant tumours or the differentiation of lymphoma and metastasis. This study aims to review literature data, as well as reveal the latest findings in the field of renal CEUS.

Analysis of multilayer and single layer X-ray detectors for contrast-enhanced mammography using imaging task

NASA Astrophysics Data System (ADS)

Allec, Nicholas; Abbaszadeh, Shiva; Karim, Karim S.

2011-03-01

A multilayer (single-shot) detector has previously been proposed for contrast-enhanced mammography. The multilayer detector has the benefit of avoiding motion artifacts due to simultaneous acquisition of both high and low energy images. A single layer (dual-shot) detector has the benefit of better control over the energy separation since the incident beams can be produced and filtered separately. In this paper the performance of the multilayer detector is compared to that of a single layer detector using an ideal observer detectability index which is determined from an extended cascaded systems model and a defined imaging task. The detectors are assumed to have amorphous selenium direct conversion layers, however the same theoretical techniques used here may be applied to other types of integrating detectors. The anatomical noise caused by variation of glandularity within the breast is known to dominate the noise power spectrum at low frequencies due to its inverse power law dependence and is thus taken into account in our model to provide an accurate estimate of the detectability index. The conditions leading to the optimal detectability index, such as tube voltage, filtration, and weight factor are reported for both detector designs.

Quantifying Uncertainty of Wind Power Production Through an Analog Ensemble

NASA Astrophysics Data System (ADS)

Shahriari, M.; Cervone, G.

2016-12-01

The Analog Ensemble (AnEn) method is used to generate probabilistic weather forecasts that quantify the uncertainty in power estimates at hypothetical wind farm locations. The data are from the NREL Eastern Wind Dataset that includes more than 1,300 modeled wind farms. The AnEn model uses a two-dimensional grid to estimate the probability distribution of wind speed (the predictand) given the values of predictor variables such as temperature, pressure, geopotential height, U-component and V-component of wind. The meteorological data is taken from the NCEP GFS which is available on a 0.25 degree grid resolution. The methodology first divides the data into two classes: training period and verification period. The AnEn selects a point in the verification period and searches for the best matching estimates (analogs) in the training period. The predictand value at those analogs are the ensemble prediction for the point in the verification period. The model provides a grid of wind speed values and the uncertainty (probability index) associated with each estimate. Each wind farm is associated with a probability index which quantifies the degree of difficulty to estimate wind power. Further, the uncertainty in estimation is related to other factors such as topography, land cover and wind resources. This is achieved by using a GIS system to compute the correlation between the probability index and geographical characteristics. This study has significant applications for investors in renewable energy sector especially wind farm developers. Lower level of uncertainty facilitates the process of submitting bids into day ahead and real time electricity markets. Thus, building wind farms in regions with lower levels of uncertainty will reduce the real-time operational risks and create a hedge against volatile real-time prices. Further, the links between wind estimate uncertainty and factors such as topography and wind resources, provide wind farm developers with valuable

Comparison of native high-resolution 3D and contrast-enhanced MR angiography for assessing the thoracic aorta.

PubMed

von Knobelsdorff-Brenkenhoff, Florian; Gruettner, Henriette; Trauzeddel, Ralf F; Greiser, Andreas; Schulz-Menger, Jeanette

2014-06-01

To omit risks of contrast agent administration, native magnetic resonance angiography (MRA) is desired for assessing the thoracic aorta. The aim was to evaluate a native steady-state free precession (SSFP) three-dimensional (3D) MRA in comparison with contrast-enhanced MRA as the gold standard. Seventy-six prospective patients with known or suspicion of thoracic aortic disease underwent MRA at 1.5 T using (i) native 3D SSFP MRA with ECG and navigator gating and high isotropic spatial resolution (1.3 × 1.3 × 1.3 mm(3)) and (ii) conventional contrast-enhanced ECG-gated gradient-echo 3D MRA (1.3 × 0.8 × 1.8 mm(3)). Datasets were compared at nine aortic levels regarding image quality (score 0-3: 0 = poor, 3 = excellent) and aortic diameters, as well as observer dependency and final diagnosis. Statistical tests included paired t-test, correlation analysis, and Bland-Altman analysis. Native 3D MRA was acquired successfully in 70 of 76 subjects (mean acquisition time 8.6 ± 2.7 min), while irregular breathing excluded 6 of 76 subjects. Aortic diameters agreed close between both methods at all aortic levels (r = 0.99; bias ± SD -0.12 ± 1.2 mm) with low intra- and inter-observer dependency (intraclass correlation coefficient 0.99). Native MRA studies resulted in the same final diagnosis as the contrast-enhanced MRA. The mean image quality score was superior with native compared with contrast-enhanced MRA (2.4 ± 0.6 vs. 1.6 ± 0.5; P < 0.001). Accuracy of aortic size measurements, certainty in defining the diagnosis and benefits in image quality at the aortic root, underscore the use of the tested high-resolution native 3D SSFP MRA as an appropriate alternative to contrast-enhanced MRA to assess the thoracic aorta. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Design of a contrast-enhanced dual-energy tomosynthesis system for breast cancer imaging

NASA Astrophysics Data System (ADS)

Hörnig, M. D.; Bätz, L.; Mertelmeier, T.

2012-03-01

Digital breast tomosynthesis (DBT) is a three-dimensional X-ray imaging modality that has the potential to decrease the superimposition effect of breast structural noise, thereby increasing lesion conspicuity. To further improve breast cancer detection, our work has been devoted to develop a prototype for contrast-enhanced dual-energy tomosynthesis (CEDET). CEDET involves the injection of an iodinated contrast agent and measures the relative increase in uptake of contrast in the suspected breast cancer lesion. Either temporal or dual-energy subtraction techniques may be used to implement CEDET. Both 2D contrast-enhanced dual-energy mammography and 3D tomosynthesis can be applied. Here we present the design of a prototype CEDET system based on the Siemens MAMMOMAT Inspiration and employing two additional high-energy filters in addition to the standard Rh filter, the latter being used for the low-energy acquisitions. A quality factor of squared signal-difference-to-noise-ratio of iodine per pixel area and average glandular dose as a function of breast thickness is used to optimize the filter material, the filter thickness, and the tube voltage. The average glandular dose can be calculated from the entrance surface air kerma using computed conversion coefficients DgN for the used X-ray spectra. We also present the results of DQE measurements of the amorphous selenium detector involved. Finally, results of phantom tests for tomosynthesis acquisition and first clinical data in the 2D mode will be shown.

Quantifying Motor Experience in the Infant Brain: EEG Power, Coherence, and Mu Desynchronization

PubMed Central

Gonzalez, Sandy L.; Reeb-Sutherland, Bethany C.; Nelson, Eliza L.

2016-01-01

The emergence of new motor skills, such as reaching and walking, dramatically changes how infants engage with the world socially and cognitively. Several examples of how motor experience can cascade into cognitive and social development have been documented, yet a significant knowledge gap remains in our understanding of whether these observed behavioral changes are accompanied by underlying neural changes. We propose that electroencephalography (EEG) measures such as power, coherence, and mu desynchronization are optimal tools to quantify motor experience in the infant brain. In this mini-review, we will summarize existing infant research that has separately assessed the relation between motor, cognitive, or social development with coherence, power, or mu desynchronization. We will discuss how the reviewed neural changes seen in seemingly separate developmental domains may be linked based on existing behavioral evidence. We will further propose that power, coherence, and mu desynchronization be used in research exploring the links between motor experience and cognitive and social development. PMID:26925022

Quantifying Emissions from the Eagle Ford Shale Using Ethane Enhancement

NASA Astrophysics Data System (ADS)

Roest, G. S.; Schade, G. W.

2014-12-01

Emissions from unconventional oil and natural gas exploration in the Eagle Ford Shale have been conjectured as a contributing factor to increasing ozone concentrations in the San Antonio Metropolitan Area, which is on track to be designated as a nonattainment area by the EPA. Primary species found in natural gas emissions are alkanes, with C3 and heavier alkanes acting as short-lived VOCs contributing to regional ozone formation. Methane emissions from the industry are also a forcing mechanism for climate change as methane is a potent greenhouse gas. Recent studies have highlighted a high variability and uncertainties in oil and natural gas emissions estimates in emissions inventories. Thus, accurately quantifying oil and natural gas emissions from the Eagle Ford Shale is necessary to assess the industry's impacts on climate forcing and regional air quality. We estimate oil and natural gas emissions in the Eagle Ford Shale using in situ ethane measurements along southwesterly trajectories from the Gulf of Mexico, dominantly during the summertime. Ethane enhancement within the drilling area is estimated by comparing ethane concentrations upwind of the shale, near the Texas coastline, to downwind measurements in the San Antonio Metropolitan Area, Odessa, and Amarillo. Upwind ethane observations indicate low background levels entering Texas in the Gulf of Mexico air masses. Significant ethane enhancement is observed between the coast and San Antonio, and is attributed to oil and natural gas operations due to the concurrent enhancements of heavier alkanes. Using typical boundary layer depths and presuming homogenous emissions across the Eagle Ford shale area, the observed ethane enhancements are used to extrapolate an estimate of oil and natural gas industry emissions in the Eagle Ford. As oil and natural gas production in the area is projected to grow rapidly over the coming years, the impacts of these emissions on regional air quality will need to be thoroughly

SU-D-207-01: Markerless Respiratory Motion Tracking with Contrast Enhanced Thoracic Cone Beam CT Projections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, M; Yuan, Y; Rosenzweig, K

2015-06-15

Purpose: To develop a novel technique to enhance the image contrast of clinical cone beam CT projections and extract respiratory signals based on anatomical motion using the modified Amsterdam Shroud (AS) method to benefit image guided radiation therapy. Methods: Thoracic cone beam CT projections acquired prior to treatment were preprocessed to increase their contrast for better respiratory signal extraction. Air intensity on raw images was firstly estimated and then applied to correct the projections to generate new attenuation images that were subsequently improved with deeper anatomy feature enhancement through taking logarithm operation, derivative along superior-inferior direction, respectively. All pixels onmore » individual post-processed two dimensional images were horizontally summed to one column and all projections were combined side by side to create an AS image from which patient’s respiratory signal was extracted. The impact of gantry rotation on the breathing signal rendering was also investigated. Ten projection image sets from five lung cancer patients acquired with the Varian Onboard Imager on 21iX Clinac (Varian Medical Systems, Palo Alto, CA) were employed to assess the proposed technique. Results: Application of the air correction on raw projections showed that more than an order of magnitude of contrast enhancement was achievable. The typical contrast on the raw projections is around 0.02 while that on attenuation images could greater than 0.5. Clear and stable breathing signal can be reliably extracted from the new images while the uncorrected projection sets failed to yield clear signals most of the time. Conclusion: Anatomy feature plays a key role in yielding breathing signal from the projection images using the AS technique. The air correction process facilitated the contrast enhancement significantly and attenuation images thus obtained provides a practical solution to obtaining markerless breathing motion tracking.« less

Differential MR Delayed Enhancement Patterns of Chronic Myocardial Infarction between Extracellular and Intravascular Contrast Media

PubMed Central

Wang, Jian; Xiang, Bo; Lin, Hung Yu; Liu, Hongyu; Freed, Darren; Arora, Rakesh C.; Tian, Ganghong

2015-01-01

Objectives Because the distribution volume and mechanism of extracellular and intravascular MR contrast media differ considerably, the enhancement pattern of chronic myocardial infarction with extracellular or intravascular media might also be different. This study aims to investigate the differences in MR enhancement patterns of chronic myocardial infarction between extracellular and intravascular contrast media. Materials and Methods Twenty pigs with myocardial infarction underwent cine MRI, first pass perfusion MRI and delayed enhancement MRI with extracellular or intravascular media at four weeks after coronary occlusion. Myocardial blood flow (MBF) was determined with microsphere measurement. The infarction histopathological changes were evaluated by hematoxylin and eosin staining and Masson's trichrome method. Results Cine MRI revealed the reduced wall thickening in chronic infarction compared with normal myocardium. Moreover, significant wall thinning in chronic infarction was observed in cine MRI. Peak first-pass signal intensity didn’t significantly differ between chronic infarction and normal myocardium no matter what kinds of contrast media. At the following delayed enhancement phase, extracellular media-enhanced signal intensity was significantly higher in chronic infarction than in normal myocardium. Conversely, intravascular media-enhanced signal intensity was almost equivalent among chronic infarction and normal myocardium. At four weeks after infarction, MBF in chronic infarction approached to that in normal myocardium. Large thick-walled vessels were detected at peri-infarction zones. The cardiomyocytes were replaced by scar tissue consisting of dilated blood vessels and discrete fibers of collagen. Conclusions Chronic infarction was characterized by the significantly reduced wall thickening and the definite wall thinning. First-pass myocardial perfusion defect was not detected in chronic infarction with two media due to the significantly

Dual-Energy Contrast-Enhanced Spectral Mammography: Enhancement Analysis on BI-RADS 4 Non-Mass Microcalcifications in Screened Women.

PubMed

Cheung, Yun-Chung; Juan, Yu-Hsiang; Lin, Yu-Ching; Lo, Yung-Feng; Tsai, Hsiu-Pei; Ueng, Shir-Hwa; Chen, Shin-Cheh

2016-01-01

Mammography screening is a cost-efficient modality with high sensitivity for detecting impalpable cancer with microcalcifications, and results in reduced mortality rates. However, the probability of finding microcalcifications without associated cancerous masses varies. We retrospectively evaluated the diagnosis and cancer probability of the non-mass screened microcalcifications by dual-energy contrast-enhanced spectral mammography (DE-CESM). With ethical approval from our hospital, we enrolled the cases of DE-CESM for analysis under the following inclusion criteria: (1) referrals due to screened BI-RADS 4 microcalcifications; (2) having DE-CESM prior to stereotactic biopsy; (3) no associated mass found by sonography and physical examination; and (4) pathology-based diagnosis using stereotactic vacuum-assisted breast biopsy. We analyzed the added value of post-contrast enhancement on DE-CESM. A total of 94 biopsed lesions were available for analysis in our 87 women, yielding 27 cancers [19 ductal carcinoma in situ (DCIS), and 8 invasive ductal carcinoma (IDC)], 32 pre-malignant and 35 benign lesions. Of these 94 lesions, 33 showed associated enhancement in DE-CESM while the other 61 did not. All 8 IDC (100%) and 16 of 19 DCIS (84.21%) showed enhancement, but the other 3 DCIS (15.79%) did not. Overall sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 88.89%, 86.56%, 72.72%, 95.08% and 87.24%, respectively. The performances of DE-CESM on both amorphous and pleomorphic microcalcifications were satisfactory (AUC 0.8 and 0.92, respectively). The pleomorphous microcalcifications with enhancement showed higher positive predictive value (90.00% vs 46.15%, p = 0.013) and higher cancer probability than the amorphous microcalcifications (46.3% VS 15.1%). The Odds Ratio was 4.85 (95% CI: 1.84-12.82). DE-CESM might provide added value in assessing the non-mass screened breast microcalcification, with enhancement favorable to the

Dual-Energy Contrast-Enhanced Spectral Mammography: Enhancement Analysis on BI-RADS 4 Non-Mass Microcalcifications in Screened Women

PubMed Central

Cheung, Yun-Chung; Juan, Yu-Hsiang; Lin, Yu-Ching; Lo, Yung-Feng; Tsai, Hsiu-Pei; Ueng, Shir-Hwa; Chen, Shin-Cheh

2016-01-01

Background Mammography screening is a cost-efficient modality with high sensitivity for detecting impalpable cancer with microcalcifications, and results in reduced mortality rates. However, the probability of finding microcalcifications without associated cancerous masses varies. We retrospectively evaluated the diagnosis and cancer probability of the non-mass screened microcalcifications by dual-energy contrast-enhanced spectral mammography (DE-CESM). Patients and Methods With ethical approval from our hospital, we enrolled the cases of DE-CESM for analysis under the following inclusion criteria: (1) referrals due to screened BI-RADS 4 microcalcifications; (2) having DE-CESM prior to stereotactic biopsy; (3) no associated mass found by sonography and physical examination; and (4) pathology-based diagnosis using stereotactic vacuum-assisted breast biopsy. We analyzed the added value of post-contrast enhancement on DE-CESM. Results A total of 94 biopsed lesions were available for analysis in our 87 women, yielding 27 cancers [19 ductal carcinoma in situ (DCIS), and 8 invasive ductal carcinoma (IDC)], 32 pre-malignant and 35 benign lesions. Of these 94 lesions, 33 showed associated enhancement in DE-CESM while the other 61 did not. All 8 IDC (100%) and 16 of 19 DCIS (84.21%) showed enhancement, but the other 3 DCIS (15.79%) did not. Overall sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 88.89%, 86.56%, 72.72%, 95.08% and 87.24%, respectively. The performances of DE-CESM on both amorphous and pleomorphic microcalcifications were satisfactory (AUC 0.8 and 0.92, respectively). The pleomorphous microcalcifications with enhancement showed higher positive predictive value (90.00% vs 46.15%, p = 0.013) and higher cancer probability than the amorphous microcalcifications (46.3% VS 15.1%). The Odds Ratio was 4.85 (95% CI: 1.84–12.82). Conclusion DE-CESM might provide added value in assessing the non-mass screened breast

Quantitative pre-clinical screening of therapeutics for joint diseases using contrast enhanced micro-computed tomography.

PubMed

Willett, N J; Thote, T; Hart, M; Moran, S; Guldberg, R E; Kamath, R V

2016-09-01

The development of effective therapies for cartilage protection has been limited by a lack of efficient quantitative cartilage imaging modalities in pre-clinical in vivo models. Our objectives were two-fold: first, to validate a new contrast-enhanced 3D imaging analysis technique, equilibrium partitioning of an ionic contrast agent-micro computed tomography (EPIC-μCT), in a rat medial meniscal transection (MMT) osteoarthritis (OA) model; and second, to quantitatively assess the sensitivity of EPIC-μCT to detect the effects of matrix metalloproteinase inhibitor (MMPi) therapy on cartilage degeneration. Rats underwent MMT surgery and tissues were harvested at 1, 2, and 3 weeks post-surgery or rats received an MMPi or vehicle treatment and tissues harvested 3 weeks post-surgery. Parameters of disease progression were evaluated using histopathology and EPIC-μCT. Correlations and power analyses were performed to compare the techniques. EPIC-μCT was shown to provide simultaneous 3D quantification of multiple parameters, including cartilage degeneration and osteophyte formation. In MMT animals treated with MMPi, OA progression was attenuated, as measured by 3D parameters such as lesion volume and osteophyte size. A post-hoc power analysis showed that 3D parameters for EPIC-μCT were more sensitive than 2D parameters requiring fewer animals to detect a therapeutic effect of MMPi. 2D parameters were comparable between EPIC-μCT and histopathology. This study demonstrated that EPIC-μCT has high sensitivity to provide 3D structural and compositional measurements of cartilage and bone in the joint. EPIC-μCT can be used in combination with histology to provide a comprehensive analysis to screen new potential therapies. Copyright © 2016 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Can the Contrast-Enhanced Ultrasound Washout Rate Be Used to Predict Microvascular Invasion in Hepatocellular Carcinoma?

PubMed

Zhu, Wei; Qing, Xiachuan; Yan, Feng; Luo, Yan; Li, Yongzhong; Zhou, Xiang

2017-08-01

The objective of this study was to investigate use of the washout rate of hepatocellular carcinoma on contrast-enhanced ultrasound (CEUS) for pre-operative determination of the presence of microvascular invasion. The study included 271 patients who underwent liver resection for hepatocellular carcinoma between April 2008 and December 2012, and were examined with contrast-enhanced ultrasound before surgery. Patients were followed up at 3-mo intervals for 3 y. Four washout patterns were classified according to the start time of washout: rapid, portal, delayed and slow. Rapid washout, presence of two or more tumors and tumor size ≥5 cm were identified as independent pre-operative predictors of microvascular invasion on multivariate analysis. Recurrence rates for patients with none, one, two or three predictors were 22.6%, 34.7%, 57.6% and 75.0%, respectively. In combination with tumor number and tumor size, contrast-enhanced ultrasound washout rate may have a role in identifying hepatocellular carcinoma patients with microvascular invasion. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Quantification of traumatic meningeal injury using dynamic contrast enhanced (DCE) fluid-attenuated inversion recovery (FLAIR) imaging

NASA Astrophysics Data System (ADS)

Castro, Marcelo A.; Williford, Joshua P.; Cota, Martin R.; MacLaren, Judy M.; Dardzinski, Bernard J.; Latour, Lawrence L.; Pham, Dzung L.; Butman, John A.

2016-03-01

Traumatic meningeal injury is a novel imaging marker of traumatic brain injury, which appears as enhancement of the dura on post-contrast T2-weighted FLAIR images, and is likely associated with inflammation of the meninges. Dynamic Contrast Enhanced MRI provides a better discrimination of abnormally perfused regions. A method to properly identify those regions is presented. Images of seventeen patients scanned within 96 hours of head injury with positive traumatic meningeal injury were normalized and aligned. The difference between the pre- and last post-contrast acquisitions was segmented and voxels in the higher class were spatially clustered. Spatial and morphological descriptors were used to identify the regions of enhancement: a) centroid; b) distance to the brain mask from external voxels; c) distance from internal voxels; d) size; e) shape. The method properly identified thirteen regions among all patients. The method failed in one case due to the presence of a large brain lesion that altered the mask boundaries. Most false detections were correctly rejected resulting in a sensitivity and specificity of 92.9% and 93.6%, respectively.

Accurate evaluation of axillary sentinel lymph node metastasis using contrast-enhanced ultrasonography with Sonazoid in breast cancer: a preliminary clinical trial.

PubMed

Matsuzawa, Fumihiko; Omoto, Kiyoka; Einama, Takahiro; Abe, Hironori; Suzuki, Takashi; Hamaguchi, Jun; Kaga, Terumi; Sato, Mami; Oomura, Masako; Takata, Yumiko; Fujibe, Ayako; Takeda, Chie; Tamura, Etsuya; Taketomi, Akinobu; Kyuno, Kenichi

2015-01-01

Breast cancer is the most common type of cancer in women. The 5-year survival rate in patients with breast cancer ranges from 74 to 82 %. Sentinel lymph node biopsy has become an alternative to axillary lymph node dissection for nodal staging. We evaluated the detection of the sentinel lymph node and metastasis of the lymph node using contrast enhanced ultrasonography with Sonazoid. Between December 2013 and May 2014, 32 patients with operable breast cancer were enrolled in this study. We evaluated the detection of axillary sentinel lymph nodes and the evaluation of axillary lymph nodes metastasis using contrast enhanced computed tomography, color Doppler ultrasonography and contrast enhanced ultrasonography with Sonazoid. All the sentinel lymph nodes were identified, and the sentinel lymph nodes detected by contrast enhanced ultrasonography with Sonazoid corresponded with those detected by computed tomography lymphography and indigo carmine method. The detection of metastasis based on contrast enhanced computed tomography were sensitivity 20.0 %, specificity 88.2 %, PPV 60.0 %, NPV 55.6 %, accuracy 56.3 %. Based on color Doppler ultrasonography, the results were sensitivity 36.4 %, specificity 95.2 %, PPV 80.0 %, NPV 74.1 %, accuracy 75.0 %. Based on contrast enhanced ultrasonography with Sonazoid, the results were sensitivity 81.8 %, specificity 95.2 %, PPV 90.0 %, NPV 90.9 %, accuracy 90.6 %. The results suggested that contrast enhanced ultrasonography with Sonazoid was the most accurate among the evaluations of these modalities. In the future, we believe that our method would take the place of conventional sentinel lymph node biopsy for an axillary staging method.

Dynamic contrast enhanced MRI of the placenta: A tool for prenatal diagnosis of placenta accreta?

PubMed

Millischer, A E; Deloison, B; Silvera, S; Ville, Y; Boddaert, N; Balvay, D; Siauve, N; Cuenod, C A; Tsatsaris, V; Sentilhes, L; Salomon, L J

2017-05-01

Ultrasound (US) is the primary imaging modality for the diagnosis of placenta accreta, but it is not sufficiently accurate. MRI morphologic criteria have recently emerged as a useful tool in this setting, but their analysis is too subjective. Recent studies suggest that gadolinium enhancement may help to distinguish between the stretched myometrium and placenta within a scar area. However, objective MRI criteria are still required for prenatal diagnosis of placenta accreta. The purpose of this study was to assess the diagnostic value of dynamic contrast gadolinium enhancement (DCE) MRI patterns for placenta accreta. MR images were acquired with a 1.5-T unit at 30-35 weeks of gestation in women with a history of Caesarian section, a low-lying anterior placenta, and US features compatible with placenta accreta. Sagittal, axial and coronal SSFP (Steady State Free Precession) sequences were acquired before injection. Then, contrast-enhanced dynamic T1-weighted images were acquired through the entire cross-sectional area of the placenta. Images were obtained sequentially at 10- to 14-s intervals for 2 min, beginning simultaneously with the bolus injection. Functional analysis was performed retrospectively, and tissular relative enhancement parameters were extracted from the recorded images. The suspected area of accreta (SAA) was placed in the region of the previous scar, and a control area (CA) of similar size was placed on the same image plane, as far as possible from the SAA. Semi-quantitative analysis of DCE-MR images was based on the kinetic enhancement curves in these two regions of interest (ROI). Three tissular relative enhancement parameters were compared according to the pregnancy outcomes, namely time to peak, maximal signal intensity, and area under the enhancement curve. We studied 9 women (43%) with accreta and 12 women (57%) with a normal placenta. All three tissular relative enhancement parameters differed significantly between the two groups (p < 10

Improved Contrast-Enhanced Ultrasound Imaging With Multiplane-Wave Imaging.

PubMed

Gong, Ping; Song, Pengfei; Chen, Shigao

2018-02-01

Contrast-enhanced ultrasound (CEUS) imaging has great potential for use in new ultrasound clinical applications such as myocardial perfusion imaging and abdominal lesion characterization. In CEUS imaging, contrast agents (i.e., microbubbles) are used to improve contrast between blood and tissue because of their high nonlinearity under low ultrasound pressure. However, the quality of CEUS imaging sometimes suffers from a low signal-to-noise ratio (SNR) in deeper imaging regions when a low mechanical index (MI) is used to avoid microbubble disruption, especially for imaging at off-resonance transmit frequencies. In this paper, we propose a new strategy of combining CEUS sequences with the recently proposed multiplane-wave (MW) compounding method to improve the SNR of CEUS in deeper imaging regions without increasing MI or sacrificing frame rate. The MW-CEUS method emits multiple Hadamard-coded CEUS pulses in each transmission event (i.e., pulse-echo event). The received echo signals first undergo fundamental bandpass filtering (i.e., the filter is centered on the transmit frequency) to eliminate the microbubble's second-harmonic signals because they cannot be encoded by pulse inversion. The filtered signals are then Hadamard decoded and realigned in fast time to recover the signals as they would have been obtained using classic CEUS pulses, followed by designed recombination to cancel the linear tissue responses. The MW-CEUS method significantly improved contrast-to-tissue ratio and SNR of CEUS imaging by transmitting longer coded pulses. The image resolution was also preserved. The microbubble disruption ratio and motion artifacts in MW-CEUS were similar to those of classic CEUS imaging. In addition, the MW-CEUS sequence can be adapted to other transmission coding formats. These properties of MW-CEUS can potentially facilitate CEUS imaging for many clinical applications, especially assessing deep abdominal organs or the heart.

Particle in cell simulation on plasma grating contrast enhancement induced by infrared laser pulse

NASA Astrophysics Data System (ADS)

Li, M.; Yuan, T.; Xu, Y. X.; Wang, J. X.; Luo, S. N.

2018-05-01

The dynamics of plasma grating contrast enhancement (PGCE) irradiated by an infrared laser pulse is investigated with one dimensional particle-in-cell simulation where field ionization and impact ionization are simultaneously considered for the first time. The numeric results show that the impact ionization dominates the PGCE process. Upon the interaction with the laser pulse, abundant free electrons are efficiently accelerated and subsequently triggered massive impact ionizations in the density ridges of the plasma grating for the higher local plasma energy density, which efficiently enhances the grating contrast. Besides the dynamic analysis of PGCE, we explore the parameter space of the incident infrared laser pulse to optimize the PGCE effect, which can provide useful guidance to experiments related to laser-plasma-grating interactions and may find applications in prolonging the duration of the plasma grating.

Perivascular epithelioid cell tumor (PEComa) of the liver diagnosed by contrast-enhanced ultrasonography.

PubMed

Akitake, Reiko; Kimura, Hiroyuki; Sekoguchi, Satoru; Nakamura, Hideki; Seno, Hiroshi; Chiba, Tsutomu; Fujimoto, Sotaro

2009-01-01

Perivascular epithelioid cell (PEC) is a unique cell which expresses both myogenic and melanocytic markers, and forms PEComa. A 36-year-old woman presented with a 35 mm-diameter liver tumor. MRI showed poor fat component in the tumor. Contrast-enhanced ultrasonography using the newly developed enhancing reagent, Sonazoid, clearly demonstrated early-phase enhancement of the tumor and rapid drainage of the reagent to veins, suggesting a PEComa. Lateral segmentectomy of the liver was performed. Histologically, epithelioid tumor cells around the vessels were immunostained with both HMB-45 and alpha-smooth muscle actin, confirming the diagnosis of PEComa. No recurrence has been found for 18 months following the operation.

Photoacoustic/ultrasound dual-modality contrast agent and its application to thermotherapy.

PubMed

Wang, Yu-Hsin; Liao, Ai-Ho; Chen, Jui-Hao; Wang, Churng-Ren Chris; Li, Pai-Chi

2012-04-01

This study investigates a photoacoustic/ultrasound dual-modality contrast agent, including extending its applications from image-contrast enhancement to combined diagnosis and therapy with site-specific targeting. The contrast agent comprises albumin-shelled microbubbles with encapsulated gold nanorods (AuMBs). The gas-filled microbubbles, whose diameters range from submicrometer to several micrometers, are not only echogenic but also can serve as drug-delivery vehicles. The gold nanorods are used to enhance the generation of both photoacoustic and photothermal signals. The optical absorption peak of the gold nanorods is tuned to 760 nm and is invariant after microbubble encapsulation. Dual-modality contrast enhancement is first described here, and the applications to cellular targeting and laser-induced thermotherapy in a phantom are demonstrated. Photoacoustic imaging can be used to monitor temperature increases during the treatment. The targeting capability of AuMBs was verified, and the temperature increased by 26°C for a laser power of 980 mW, demonstrating the potential of combined diagnosis and therapy with the dual-modality agent. Targeted photo- or acoustic-mediated delivery is also possible.

Contrast-enhanced harmonic endoscopic ultrasound in solid lesions of the pancreas: results of a pilot study.

PubMed

Napoleon, B; Alvarez-Sanchez, M V; Gincoul, R; Pujol, B; Lefort, C; Lepilliez, V; Labadie, M; Souquet, J C; Queneau, P E; Scoazec, J Y; Chayvialle, J A; Ponchon, T

2010-07-01

Distinguishing pancreatic adenocarcinoma from other pancreatic masses remains challenging with current imaging techniques. This prospective study aimed to evaluate the accuracy of a new procedure, imaging the microcirculation pattern of the pancreas by contrast-enhanced harmonic endoscopic ultrasound (CEH-EUS) with a new Olympus prototype echo endoscope. 35 patients presenting with solid pancreatic lesions were prospectively enrolled. All patients had conventional B mode and power Doppler EUS. After an intravenous bolus injection of 2.4 ml of a second-generation ultrasound contrast agent (SonoVue) CEH-EUS was then performed with a new Olympus prototype echo endoscope (xGF-UCT 180). The microvascular pattern was compared with the final diagnosis based on the pathological examination of specimens from surgery or EUS-guided fine-needle aspiration (EUS-FNA) or on follow-up for at least 12 months. The final diagnoses were: 18 adenocarcinomas, 9 neuroendocrine tumors, 7 chronic pancreatitis, and 1 stromal tumor. Power Doppler failed to display microcirculation, whereas harmonic imaging demonstrated it in all cases. Out of 18 lesions with a hypointense signal on CEH-EUS, 16 were adenocarcinomas. The sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and accuracy of hypointensity for diagnosing pancreatic adenocarcinoma were 89 %, 88 %, 88 %, 89 %, and 88.5 %, compared with corresponding values of 72 %, 100 %, 77 %, 100 %, and 86 % for EUS-FNA. Of five adenocarcinomas with false-negative results at EUS-FNA, four had a hypointense echo signal at CEH-EUS. CEH-EUS with the new Olympus prototype device successfully visualizes the microvascular pattern in pancreatic solid lesions, and may be useful for distinguishing adenocarcinomas from other pancreatic masses.

Non-contrast-enhanced MR portography and hepatic venography with time-spatial labeling inversion pulses: comparison of imaging with the short tau inversion recovery method and the chemical shift selective method.

PubMed

Shimizu, Hironori; Isoda, Hiroyoshi; Ohno, Tsuyoshi; Yamashita, Rikiya; Kawahara, Seiya; Furuta, Akihiro; Fujimoto, Koji; Kido, Aki; Kusahara, Hiroshi; Togashi, Kaori

2015-01-01

To compare and evaluate images of non-contrast enhanced magnetic resonance (MR) portography and hepatic venography acquired with two different fat suppression methods, the chemical shift selective (CHESS) method and short tau inversion recovery (STIR) method. Twenty-two healthy volunteers were examined using respiratory-triggered three-dimensional true steady-state free-precession with two time-spatial labeling inversion pulses. The CHESS or STIR methods were used for fat suppression. The relative signal-to-noise ratio and contrast-to-noise ratio (CNR) were quantified, and the quality of visualization was scored. Image acquisition was successfully conducted in all volunteers. The STIR method significantly improved the CNRs of MR portography and hepatic venography. The image quality scores of main portal vein and right portal vein were higher with the STIR method, but there were no significant differences. The image quality scores of right hepatic vein, middle hepatic vein, and left hepatic vein (LHV) were all higher, and the visualization of LHV was significantly better (p<0.05). The STIR method contributes to further suppression of the background signal and improves visualization of the portal and hepatic veins. The results support using non-contrast-enhanced MR portography and hepatic venography in clinical practice. Copyright © 2014 Elsevier Inc. All rights reserved.

Enhancing light-harvesting power with coherent vibrational interactions: A quantum heat engine picture

NASA Astrophysics Data System (ADS)

Killoran, N.; Huelga, S. F.; Plenio, M. B.

2015-10-01

Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations may contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system's power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principle and quantifies its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle's relevance in parameter regimes connected to natural light-harvesting structures.

The role of contrast-enhanced ultrasound in imaging carotid arterial diseases.

PubMed

Clevert, Dirk A; Paprottka, Philipp; Sommer, Wieland H; Helck, Andreas; Reiser, Maximilian F; Zengel, Pamela

2013-06-01

The standard of care for the initial diagnosis of carotid artery bifurcation diseases is carotid duplex ultrasound. Carotid abnormalities or difficult examinations may represent a diagnostic challenge in patients with clinical symptoms as well as in the follow-up after carotid endarterectomy, carotid artery stenting or other interventions. A promising new method in the diagnosis and follow-up of pathologic carotid diseases is contrast-enhanced ultrasound (CEUS). In comparison with magnetic resonance imaging or computed tomography, the contrast agents used for CEUS remain within the vascular space and hence can be used to study vascular disease and could provide additional information on carotid arterial diseases. This review describes the current carotid duplex ultrasound examination and compares the pathologic findings with CEUS. Copyright © 2013 Elsevier Inc. All rights reserved.

Correlation between blood and lymphatic vessel density and results of contrast-enhanced spectral mammography.

PubMed

Luczynska, Elzbieta; Niemiec, Joanna; Ambicka, Aleksandra; Adamczyk, Agnieszka; Walasek, Tomasz; Ryś, Janusz; Sas-Korczyńska, Beata

2015-09-01

Contrast-enhanced spectral mammography (CESM) is a novel technique used for detection of tumour vascularity by imaging the moment in which contrast, delivered to the lesion by blood vessels, leaks out of them, and flows out through lymphatic vessels. In our study, we included 174 women for whom spectral mammography was performed for diagnostic purposes. The relationship between enhancement in CESM and blood vessel density (BVD), lymphatic vessel density (LVD) or the percentage of fields with at least one lymphatic vessel (distribution of podoplanin-positive vessels - DPV) and other related parameters was assessed in 55 cases. BVD, LVD and DPV were assessed immunohistochemically, applying podoplanin and CD31/CD34 as markers of lymphatic and blood vessels, respectively. The sensitivity (in detection of malignant lesions) of CESM was 100%, while its specificity - 39%. We found a significant positive correlation between the intensity of enhancement in CESM and BVD (p = 0.007, r = 0.357) and a negative correlation between the intensity of enhancement in CESM and DPV (p = 0.003, r = -0.390). Lesions with the highest enhancement in CESM showed a high number of blood vessels and a low number of lymphatics. 1) CESM is a method characterized by high sensitivity and acceptable specificity; 2) the correlation between CESM results and blood/lymphatic vessel density confirms its utility in detection of tissue angiogenesis and/or lymphangiogenesis.

Current consensus and guidelines of contrast enhanced ultrasound for the characterization of focal liver lesions

PubMed Central

Jang, Jae Young; Kim, Moon Young; Jeong, Soung Won; Kim, Tae Yeob; Kim, Seung Up; Lee, Sae Hwan; Suk, Ki Tae; Park, Soo Young; Woo, Hyun Young; Kim, Sang Gyune; Heo, Jeong; Baik, Soon Koo; Kim, Hong Soo

2013-01-01

The application of ultrasound contrast agents (UCAs) is considered essential when evaluating focal liver lesions (FLLs) using ultrasonography (US). Microbubble UCAs are easy to use and robust; their use poses no risk of nephrotoxicity and requires no ionizing radiation. The unique features of contrast enhanced US (CEUS) are not only noninvasiveness but also real-time assessing of liver perfusion throughout the vascular phases. The later feature has led to dramatic improvement in the diagnostic accuracy of US for detection and characterization of FLLs as well as the guidance to therapeutic procedures and evaluation of response to treatment. This article describes the current consensus and guidelines for the use of UCAs for the FLLs that are commonly encountered in US. After a brief description of the bases of different CEUS techniques, contrast-enhancement patterns of different types of benign and malignant FLLs and other clinical applications are described and discussed on the basis of our experience and the literature data. PMID:23593604

Dynamic contrast-enhanced magnetic resonance imaging of the sarcopenic muscle

PubMed Central

Nicolato, Elena; Farace, Paolo; Asperio, Roberto M; Marzola, Pasquina; Lunati, Ernesto; Sbarbati, Andrea; Osculati, Francesco

2002-01-01

Background Studies about capillarity of the aged muscle provided conflicting results and no data are currently available about the magnetic resonance imaging (MRI) in vivo characteristics of the microvascular bed in aged rats. We have studied age-related modifications of the skeletal muscle by in vivo T2-relaxometry and dynamic contrast-enhanced magnetic resonance imaging (CE-MRI) at high field intensity (4.7 T). The aim of the work was to test the hypothesis that the ageing process involves microvessels in skeletal muscle. Methods The study was performed in 4-month-old (n = 6) and 20-month-old (n = 6) rats. Results At MRI examination, the relaxation time T2 of the gastrocnemius muscle showed no significant difference between these two groups. The kinetic of contrast penetration in the tissue showed that in 4-month-old rats the enhancement values of the signal intensity at different time-points were significantly higher than those found in senescent rats. Conclusion The reported finding suggests that there is a modification of the microcirculatory function in skeletal muscle of aged rats. This work also demonstrates that CE-MRI allows for an in vivo quantification of the multiple biological processes involving the skeletal muscle during aging. Therefore, CE-MRI could represent a further tool for the follow up of tissue modification and therapeutic intervention both in patients with sarcopenia and in experimental models of this pathology. PMID:12049675

Transabdominal contrast-enhanced ultrasound imaging of the prostate.

PubMed

Mischi, Massimo; Demi, Libertario; Smeenge, Martijn; Kuenen, Maarten P J; Postema, Arnoud W; de la Rosette, Jean J M C H; Wijkstra, Hessel

2015-04-01

Numerous age-related pathologies affect the prostate gland, the most menacing of which is prostate cancer (PCa). The diagnostic tools for prostate investigation are invasive, requiring biopsies when PCa is suspected. Novel dynamic contrast-enhanced ultrasound (DCE-US) imaging approaches have been proposed recently and appear promising for minimally invasive localization of PCa. Ultrasound imaging of the prostate is traditionally performed with a transrectal probe because the location of the prostate allows for high-resolution images using high-frequency transducers. However, DCE-US imaging requires lower frequencies to induce bubble resonance and, thus, improve contrast-to-tissue ratio. For this reason, in this study we investigate the feasibility of quantitative DCE-US imaging of the prostate via the abdomen. The study included 10 patients (age = 60.7 ± 5.7 y) referred for a needle biopsy study. After having given informed consent, patients underwent DCE-US with both transabdominal and transrectal probes. Time-intensity contrast curves were derived using both approaches and their model-fit quality was compared. Although further improvements are expected by optimization of the transabdominal settings, the results of transabdominal and transrectal DCE-US are closely comparable, confirming the feasibility of transabdominal DCE-US; transabdominal curve fitting revealed an average determination coefficient r(2) = 0.91 (r(2) > 0.75 for 78.6% of all prostate pixels) compared with r(2) = 0.91 (r(2) > 0.75 for 81.6% of all prostate pixels) by the transrectal approach. Replacing the transrectal approach with more acceptable transabdominal scanning for prostate investigation is feasible. This approach would improve patient comfort and represent a useful option for PCa localization and monitoring. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

[Investigation of renal corticomedullary differentiation with age-related change on non-contrast-enhanced MRI].

PubMed

Shang, J N; Ren, K; Wu, W S; Lu, T; Sun, W G; Zhang, H G; Li, X D; Liu, Y

2016-05-24

To evaluate the relationship between renal corticomedullary differentiation, renal cortical thickness and age-related changes with non-contrast-enhanced steady-state free precession(SSFP) magnetic resonance imaging (MRI) and spatially selective inversion recovery(IR) pulse technology as well as its applied value . A total of 76 healthy volunteers had been recruited from August 2014 to June 2015 in First Hospital of China Medical University.All volunteers were divided into three groups: 2-40 years old, 41-60 years old, 61-80 years old. All 76 volunteers underwent non-contrast-enhanced steady-state free precession(SSFP) 3.0 T MRI scan using variable inversion times (TIs)(TI=1 000, 1 100, 1 200, 1 300, 1 400, 1 500, 1 600, 1 700 ms). The renal corticomedullary differentiation was observed and the signal intensity of renal cortex and medulla were measured respectively as well in order to calculate renal corticomedullary contrast ratio. Besides, renal cortical thickness and renal size were measured. All 76 volunteers were successfully performed all the sequences of MRI scan, including 152 useful imaging of kidney in total. The renal corticomedullary differentiation was clearly shown in all subjects. There was negative correlation between the optimal inversion time(TI) and age(r=-0.65, P<0.01). Similarly, negative correlation was observed between renal corticomedullary contrast ratio and age(r=-0.35, P<0.01). The mean renal cortical thickness of all subjects was (5.33±0.71)mm and there were statistically significant difference among those different groups, which was negative-related with age(r=-0.79, P<0.01). There was no statistically significant difference between sexuality and renal cortical thickness.Additionally, renal cortical thickness had no statistically significant difference in both sides of kidneys. The renal corticomedullary differentiation is depicted clearly by means of non-contrast-enhanced steady-state free precession MRI with spatially selective

Low-Molecular-Weight Iron Chelates May Be an Alternative to Gadolinium-based Contrast Agents for T1-weighted Contrast-enhanced MR Imaging.

PubMed

Boehm-Sturm, Philipp; Haeckel, Akvile; Hauptmann, Ralf; Mueller, Susanne; Kuhl, Christiane K; Schellenberger, Eyk A

2018-02-01

Purpose To synthesize two low-molecular-weight iron chelates and compare their T1 contrast effects with those of a commercial gadolinium-based contrast agent for their applicability in dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging. Materials and Methods The animal experiments were approved by the local ethics committee. Two previously described iron (Fe) chelates of pentetic acid (Fe-DTPA) and of trans-cyclohexane diamine tetraacetic acid (Fe-tCDTA) were synthesized with stability constants several orders of magnitude higher than those of gadolinium-based contrast agents. The T1 contrast effects of the two chelates were compared with those of gadopentetate dimeglumine in blood serum phantoms at 1.5 T, 3 T, and 7 T. For in vivo studies, a human breast cancer cell line (MDA-231) was implanted in five mice per group. The dynamic contrast effects of the chelates were compared by performing DCE MR imaging with intravenous application of Fe-DTPA or Fe-tCDTA on day 1 and DCE MR imaging in the same tumors with gadopentetate dimeglumine on day 2. Quantitative DCE maps were generated with software and were compared by means of a one-tailed Pearson correlation test. Results Relaxivities in serum (0.94 T at room temperature) of Fe-tCDTA (r1 = 2.2 mmol -1 · sec -1 , r2 = 2.5 mmol -1 · sec -1 ) and Fe-DTPA (r1 = 0.9 mmol -1 · sec -1 , r2 = 0.9 mmol -1 · sec -1 ) were approximately twofold and fivefold lower, respectively, compared with those of gadopentetate dimeglumine (r1 = 4.1 mmol -1 · sec -1 , r2 = 4.8 mmol -1 · sec -1 ). Used at moderately higher concentrations, however, iron chelates generated similar contrast effects at T1-weighted MR imaging in vitro in serum, in vivo in blood, and for DCE MR imaging of breast cancer xenografts. The volume transfer constant values for Fe-DTPA and Fe-tCDTA in the same tumors correlated well with those observed for gadopentetate dimeglumine (Fe-tCDTA Pearson R, 0.99; P = .0003; Fe-DTPA Pearson R, 0.97; P

Degree of Enhancement on Contrast Enhanced Spectral Mammography (CESM) and Lesion Type on Mammography (MG): Comparison Based on Histological Results

PubMed Central

Łuczyńska, Elżbieta; Niemiec, Joanna; Hendrick, Edward; Heinze, Sylwia; Jaszczyński, Janusz; Jakubowicz, Jerzy; Sas-Korczyńska, Beata; Rys, Janusz

2016-01-01

Background Contrast enhanced spectral mammography (CESM) is a new method of breast cancer diagnosis in which an iodinated contrast agent is injected and dual-energy mammography is obtained in multiple views of the breasts. The aim of this study was to compare the degree of enhancement on CESM with lesion characteristics on mammography (MG) and lesion histology in women with suspicious breast lesions. Material/Methods The degree of enhancement on CESM (absent, weak, medium, or strong) was compared to lesion characteristics on MG (mass, mass with microcalcifications, or microcalcifications alone) and histology (infiltrating carcinoma, intraductal carcinoma, or benign) to compare sensitivity of the two modalities and to establish correlations that might improve diagnostic accuracy. Results Among 225 lesions identified with CESM and MG, histological evaluation revealed 143 carcinomas (127 infiltrating, 16 intraductal) and 82 benign lesions. This is the largest cohort investigated with CESM to date. The sensitivity of CESM was higher than that of MG (100% and 90%, respectively, p=0.010). Medium or strong enhancement on CESM and the presence of a mass on MG was the most likely indictor of malignancy (55.1% p=0.002). Among benign lesions, 60% presented as enhancement on CESM (were false-positive), and most frequently as medium or weak enhancement, together with a mass on MG (53%, p=0.047). Unfortunately, the study did not find combinations of MG findings and CESM enhancement patterns that would be helpful in defining false-positive lesions. We observed systematic overestimation of maximum lesion diameter on CESM compared to histology (mean difference: 2.29 mm). Conclusions Strong or medium enhancement on CESM and mass or mass with microcalcifications on MG were strong indicators of malignant transformation. However, we found no combination of MG and CESM characteristics helpful in defining false-positive lesions. PMID:27768681

Degree of Enhancement on Contrast Enhanced Spectral Mammography (CESM) and Lesion Type on Mammography (MG): Comparison Based on Histological Results.

PubMed

Łuczyńska, Elżbieta; Niemiec, Joanna; Hendrick, Edward; Heinze, Sylwia; Jaszczyński, Janusz; Jakubowicz, Jerzy; Sas-Korczyńska, Beata; Rys, Janusz

2016-10-21

BACKGROUND Contrast enhanced spectral mammography (CESM) is a new method of breast cancer diagnosis in which an iodinated contrast agent is injected and dual-energy mammography is obtained in multiple views of the breasts. The aim of this study was to compare the degree of enhancement on CESM with lesion characteristics on mammography (MG) and lesion histology in women with suspicious breast lesions. MATERIAL AND METHODS The degree of enhancement on CESM (absent, weak, medium, or strong) was compared to lesion characteristics on MG (mass, mass with microcalcifications, or microcalcifications alone) and histology (infiltrating carcinoma, intraductal carcinoma, or benign) to compare sensitivity of the two modalities and to establish correlations that might improve diagnostic accuracy. RESULTS Among 225 lesions identified with CESM and MG, histological evaluation revealed 143 carcinomas (127 infiltrating, 16 intraductal) and 82 benign lesions. This is the largest cohort investigated with CESM to date. The sensitivity of CESM was higher than that of MG (100% and 90%, respectively, p=0.010). Medium or strong enhancement on CESM and the presence of a mass on MG was the most likely indictor of malignancy (55.1% p=0.002). Among benign lesions, 60% presented as enhancement on CESM (were false-positive), and most frequently as medium or weak enhancement, together with a mass on MG (53%, p=0.047). Unfortunately, the study did not find combinations of MG findings and CESM enhancement patterns that would be helpful in defining false-positive lesions. We observed systematic overestimation of maximum lesion diameter on CESM compared to histology (mean difference: 2.29 mm). CONCLUSIONS Strong or medium enhancement on CESM and mass or mass with microcalcifications on MG were strong indicators of malignant transformation. However, we found no combination of MG and CESM characteristics helpful in defining false-positive lesions.

Does intravenous contrast-enhanced computed tomography cause acute kidney injury? Protocol of a systematic review of the evidence

PubMed Central

2014-01-01

Background Contrast-induced acute kidney injury is a common cause of iatrogenic acute kidney injury (AKI). Most of the published estimates of AKI after contrast use originate from the cardiac catheterization literature despite contrast-enhanced computed tomography (CT) scans being the more common setting for contrast use. This systematic review aims to summarize the current evidence about (1)the risk of AKI following intravenous (IV) contrast-enhanced CT scans and(2) the risk of clinical outcomes (i.e. death, hospitalization and need for renal replacement therapy) due to IV contrast-enhanced CT scans. Methods/Design A systematic literature search for published studies will be performed using MEDLINE, EMBASE and The COCHRANE Library databases. Unpublished studies will be identified by searching through grey literature. No language restriction will be applied. The review will consider all studies that have examined the association between IV contrast media and AKI. To be selected, the study should include two arms: one group of exposed patients who received IV contrast material before CT scans and one group of unexposed group who did not receive contrast material before CT scans. Two authors will independently screen titles and abstracts obtained from electronic databases, extract data and will assess the quality of the studies selected using the Cochrane's ‘Risk of Bias’ assessment tool for randomized trials and the Newcastle-Ottawa Scale for observational studies. A random-effects meta-analysis will be performed if there is no remarkable heterogeneity between studies. Discussion This systematic review will provide synthesis of current evidence around the effect of IV contrast material on AKI and other clinical outcomes. Results will be helpful for making evidence-based recommendations and guidelines for clinical and radiologic settings. Systematic review registration PROSPERO CRD42013003799. PMID:25148933

Lipid-based nanoparticles for contrast-enhanced MRI and molecular imaging.

PubMed

Mulder, Willem J M; Strijkers, Gustav J; van Tilborg, Geralda A F; Griffioen, Arjan W; Nicolay, Klaas

2006-02-01

In the field of MR imaging and especially in the emerging field of cellular and molecular MR imaging, flexible strategies to synthesize contrast agents that can be manipulated in terms of size and composition and that can be easily conjugated with targeting ligands are required. Furthermore, the relaxivity of the contrast agents, especially for molecular imaging applications, should be very high to deal with the low sensitivity of MRI. Lipid-based nanoparticles, such as liposomes or micelles, have been used extensively in recent decades as drug carrier vehicles. A relatively new and promising application of lipidic nanoparticles is their use as multimodal MR contrast agents. Lipids are amphiphilic molecules with both a hydrophobic and a hydrophilic part, which spontaneously assemble into aggregates in an aqueous environment. In these aggregates, the amphiphiles are arranged such that the hydrophobic parts cluster together and the hydrophilic parts face the water. In the low concentration regime, a wide variety of structures can be formed, ranging from spherical micelles to disks or liposomes. Furthermore, a monolayer of lipids can serve as a shell to enclose a hydrophobic core. Hydrophobic iron oxide particles, quantum dots or perfluorocarbon emulsions can be solubilized using this approach. MR-detectable and fluorescent amphiphilic molecules can easily be incorporated in lipidic nanoparticles. Furthermore, targeting ligands can be conjugated to lipidic particles by incorporating lipids with a functional moiety to allow a specific interaction with molecular markers and to achieve accumulation of the particles at disease sites. In this review, an overview of different lipidic nanoparticles for use in MRI is given, with the main emphasis on Gd-based contrast agents. The mechanisms of particle formation, conjugation strategies and applications in the field of contrast-enhanced, cellular and molecular MRI are discussed. 2006 John Wiley & Sons, Ltd.

New subtraction algorithms for evaluation of lesions on dynamic contrast-enhanced MR mammography.

PubMed

Choi, Byung Gil; Kim, Hak Hee; Kim, Euy Neyng; Kim, Bum-soo; Han, Ji-Youn; Yoo, Seung-Schik; Park, Seog Hee

2002-12-01

We report new subtraction algorithms for the detection of lesions in dynamic contrast-enhanced MR mammography(CE MRM). Twenty-five patients with suspicious breast lesions underwent dynamic CE MRM using 3D fast low-angle shot. After the acquisition of the T1-weighted scout images, dynamic images were acquired six times after the bolus injection of contrast media. Serial subtractions, step-by-step subtractions, and reverse subtractions, were performed. Two radiologists attempted to differentiate benign from malignant lesion in consensus. The sensitivity, specificity, and accuracy of the method leading to the differentiation of malignant tumor from benign lesions were 85.7, 100, and 96%, respectively. Subtraction images allowed for better visualization of the enhancement as well as its temporal pattern than visual inspection of dynamic images alone. Our findings suggest that the new subtraction algorithm is adequate for screening malignant breast lesions and can potentially replace the time-intensity profile analysis on user-selected regions of interest.