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1.
Role of portal vein tumor thrombosis in quantitative perfusion analysis of contrast-enhanced ultrasound of hepatocellular carcinoma.
Wang, Z, Liu, G, Lu, MD, Xie, X, Kuang, M, Wang, W, Xu, Z, Lin, M, Chen, L
Ultrasound in medicine & biology. 2015;(5):1277-86
Abstract
The goal of our study was to evaluate the differences between quantitative parameters of hepatocellular carcinoma (HCC) with or without portal vein tumor thrombosis (PVTT) on contrast-enhanced ultrasound (CEUS). Twenty-four patients with HCC with PVTT and 48 without PVTT underwent CEUS using sulfur hexafluoride microbubbles. Dynamic images were analyzed with quantification software. Time-intensity curves were obtained for HCC and surrounding liver parenchyma, and parameters including the intensity maximum (IMAX), rising time (RT), mean transit time and time to peak (TTP) were compared within and between the PVTT and control groups, respectively. RT and TTP of HCC were significantly faster than those of surrounding liver parenchyma in both the PVTT and control groups. IMAX of HCC was significantly stronger than that of surrounding liver in the control group, but not significantly different from that of liver parenchyma in the PVTT group. RT and TTP of HCC and surrounding liver were significantly faster in the PVTT group compared with the control group, whereas IMAX values of HCC in the PVTT group were lower than those in the control group. HCC with PVTT presents different hemodynamic parameters, with faster RT and TTP and lower IMAX than those for HCC without PVTT. Quantitative perfusion analysis of CEUS may be a potential method for predicting PVTT.
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Changes in brain regions associated with food-intake regulation, body mass and metabolic profiles during acute antipsychotic treatment in first-episode schizophrenia.
Emsley, R, Asmal, L, Chiliza, B, du Plessis, S, Carr, J, Kidd, M, Malhotra, AK, Vink, M, Kahn, RS
Psychiatry research. 2015;(2):186-93
Abstract
We investigated whether morphological brain changes occurred in brain regions associated with body-weight homeostasis during acute antipsychotic treatment, and if so, whether they were related to changes in body mass and metabolic profile. Twenty-two antipsychotic-naive patients with first-episode schizophrenia received either risperidone long acting injection or flupenthixol decanoate over 13 weeks and were compared by structural MRI with 23 matched healthy volunteers at weeks 0, 4 and 13. Images were reconstructed using freesurfer fully-automated whole brain segmentation. The ventral diencephalon and prefrontal cortex were selected to represent the homeostatic and hedonic food intake regulatory systems respectively. Body mass was measured at weeks 0, 7 and 13 and fasting glucose and lipid profiles at weeks 0 and 13. Linear mixed effect models indicated significant group(⁎)time interactions for the ventral diencephalon volumes bilaterally. Ventral diencephalon volume reduction was strongly correlated bilaterally with body mass increase and HDL-cholesterol reductions, and unilaterally with blood glucose elevation. There were no significant changes in prefrontal cortical thickness. These findings implicate the ventral diencephalon, of which the hypothalamus is the main component, in the acute adipogenic and dyslipidaemic effects of antipsychotic medication.
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Cardiac calcium score on 2D echo: correlations with cardiac and coronary calcium at multi-detector computed tomography.
Gaibazzi, N, Baldari, C, Faggiano, P, Albertini, L, Faden, G, Pigazzani, F, Rossi, C, Reverberi, C
Cardiovascular ultrasound. 2014;:43
Abstract
BACKGROUND To test the hypothesis that a semi-quantitative echocardiographic calcium score (eCS) significantly correlates with cardiac calcium measured by coronary computed tomography angiography (CCTA) and, secondarily, severe coronary artery calcifications and stenosis. METHODS This is a retrospective, observational study, conducted in a tertiary centre. eCS was compared with CCTA scores of non-coronary cardiac calcium (nCACS), coronary cardiac calcium (CACS) and number of diseased coronary vessels, in 141 subjects without known coronary artery disease (CAD), who underwent both echocardiography and CCTA for clinical reasons. RESULTS Age, prevalence of hypertension and all measures of calcium (eCS, nCACS and CACS) differed significantly between the no-CAD and CAD subgroups. eCS was positively correlated with nCACS (Spearman rho = 0.64, p < 0.0001), CACS (rho = 0.46, p < 0.01) and weakly with the number of diseased coronary vessels (rho = 0.28, p < 0.05). eCS and nCACS had similar area under the curve (AUC) for the prediction of severe CACS (≥400) (0.77, 95% CI 0.68-0.86 and 0.79, 95% CI 0.72-0.88) or obstructive CAD (0.63, 95% CI 0.54-0.72 and 0.63, 95% CI 0.55-0.73). CONCLUSIONS eCS, a calcium score easily obtainable during standard echocardiography, is moderately to strongly correlated with nCACS by CCTA. The full eCS score correlates with nCACS better than its single components. It correlates with CACS and predicts severe coronary calcification (CACS > 400), a known predictor of cardiovascular morbidity and mortality. The eCS also predicts obstructive CAD, incrementally to age and clinical variables, although for this purpose CACS remains the most accurate score.
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DCE-MRI of the liver: effect of linear and nonlinear conversions on hepatic perfusion quantification and reproducibility.
Aronhime, S, Calcagno, C, Jajamovich, GH, Dyvorne, HA, Robson, P, Dieterich, D, Fiel, MI, Martel-Laferriere, V, Chatterji, M, Rusinek, H, et al
Journal of magnetic resonance imaging : JMRI. 2014;(1):90-8
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Abstract
PURPOSE To evaluate the effect of different methods to convert magnetic resonance (MR) signal intensity (SI) to gadolinium concentration ([Gd]) on estimation and reproducibility of model-free and modeled hepatic perfusion parameters measured with dynamic contrast-enhanced (DCE)-MRI. MATERIALS AND METHODS In this Institutional Review Board (IRB)-approved prospective study, 23 DCE-MRI examinations of the liver were performed on 17 patients. SI was converted to [Gd] using linearity vs. nonlinearity assumptions (using spoiled gradient recalled echo [SPGR] signal equations). The [Gd] vs. time curves were analyzed using model-free parameters and a dual-input single compartment model. Perfusion parameters obtained with the two conversion methods were compared using paired Wilcoxon test. Test-retest and interobserver reproducibility of perfusion parameters were assessed in six patients. RESULTS There were significant differences between the two conversion methods for the following parameters: AUC60 (area under the curve at 60 s, P < 0.001), peak gadolinium concentration (Cpeak, P < 0.001), upslope (P < 0.001), Fp (portal flow, P = 0.04), total hepatic flow (Ft, P = 0.007), and MTT (mean transit time, P < 0.001). Our preliminary results showed acceptable to good reproducibility for all model-free parameters for both methods (mean coefficient of variation [CV] range, 11.87-23.7%), except for upslope (CV = 37%). Among modeled parameters, DV (distribution volume) had CV <22% with both methods, PV and MTT showed CV <21% and <29% using SPGR equations, respectively. Other modeled parameters had CV >30% with both methods. CONCLUSION Linearity assumption is acceptable for quantification of model-free hepatic perfusion parameters while the use of SPGR equations and T1 mapping may be recommended for the quantification of modeled hepatic perfusion parameters.
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Diagnostic value of three-dimensional contrast-enhanced echocardiography for left ventricular volume and ejection fraction measurement in patients with poor acoustic windows: a comparison of echocardiography and magnetic resonance imaging.
Saloux, E, Labombarda, F, Pellissier, A, Anthune, B, Dugué, AE, Provost, N, Allain, P, De Craene, M, Milliez, P, Manrique, A
Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 2014;(10):1029-40
Abstract
BACKGROUND Three-dimensional echocardiography (3DE) is a reliable and reproducible tool for assessing left ventricular (LV) function but remains sensitive to patient echogenicity. Contrast-enhanced 3DE (C3DE) has the potential to improve quantification in challenging patients. The aim of this study was to evaluate the impact of temporal resolution, spatial resolution, and image dynamic range on LV function assessed using C3DE compared with cardiac magnetic resonance imaging (MRI) in patients with poor echogenicity. METHODS Forty-one patients with poor echogenicity who underwent two-dimensional echocardiography (2DE), 3DE, C3DE, and MRI were retrospectively investigated. RESULTS Before contrast injection, 24 patients had three or more nonvisible segments. Three cases of 2DE and 12 cases of 3DE were not suitable for quantification. LV end-diastolic volumes were systematically underestimated by 2DE (142 ± 58 mL), 3DE (146 ± 69 mL), and C3DE (172 ± 61 mL) compared with MRI (216 ± 85 mL) (P < .001). Similar results were found for LV end-systolic volumes (81 ± 65 mL for 2DE, 82 ± 69 mL for 3DE, and 102 ± 80 mL for C3DE vs 129 ± 94 mL for MRI; P < .001). C3DE provided the best agreement with MRI (Lin concordance correlation coefficients of 0.67, 0.93, and 0.99, respectively, for end-diastolic volume, end-systolic volume, and ejection fraction) as well as the best measurement reproducibility. Finally, ultrasound settings had no significant effect on LV volumes and ejection fraction measurements. CONCLUSIONS In these patients with poor ultrasound image quality, C3DE, regardless of instrument settings, outperformed 2DE and 3DE to assess LV volumes and ejection fraction and can thus be proposed as an acceptable alternative when MRI cannot be performed in this subgroup.
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Comparison of T1 relaxation times in adipose tissue of severely obese patients and healthy lean subjects measured by 1.5 T MRI.
Garnov, N, Linder, N, Schaudinn, A, Blüher, M, Karlas, T, Schütz, T, Dietrich, A, Kahn, T, Busse, H
NMR in biomedicine. 2014;(9):1123-8
Abstract
Subcutaneous (SAT) and visceral adipose tissue (VAT) differ in composition, endocrine function and localization in the body. VAT is considered to play a role in the pathogenesis of insulin resistance, type 2 diabetes, fatty liver disease, and other obesity-related disorders. It has been shown that the amount, distribution, and (cellular) composition of adipose tissue (AT) correlate well with metabolic conditions. In this study, T1 relaxation times of AT were measured in severely obese subjects and compared with those of healthy lean controls. Here, we tested the hypothesis that T1 relaxation times of AT differ between lean and obese individuals, but also between VAT and SAT as well as superficial (sSAT) and deep SAT (dSAT) in the same individual. Twenty severely obese subjects (BMI 41.4 ± 4.8 kg/m(2) ) and ten healthy lean controls matched for age (BMI 21.5 ± 1.9 kg/m(2) ) underwent MRI at 1.5 T using a single-shot fast spin-echo sequence (short-tau inversion recovery) at six different inversion times (TI range 100-1000 ms). T1 relaxation times were computed for all subjects by fitting the TI -dependent MR signal intensities of user-defined regions of interest in both SAT and VAT to a model function. T1 times in sSAT and dSAT were only measured in obese patients. For both obese patients and controls, the T1 times of SAT (275 ± 14 and 301 ± 12 ms) were significantly (p < 0.01) shorter than the respective values in VAT (294 ± 20 and 360 ± 35 ms). Obese subjects also showed significant (p < 0.01) T1 differences between sSAT (268 ± 11 ms) and dSAT (281 ± 19 ms). More important, T1 differences in both SAT and VAT were highly significant (p < 0.001) between obese patients and healthy subjects. The results of our pilot study suggest that T1 relaxation times differ between severely obese patients and lean controls, and may potentially provide an additional means for the non-invasive assessment of AT conditions and dysfunction.
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Development and validation of a predictive screening tool for uninterpretable coronary CT angiography results.
Vanhecke, TE, Madder, RD, Weber, JE, Bielak, LF, Peyser, PA, Chinnaiyan, KM
Circulation. Cardiovascular imaging. 2011;(5):490-7
Abstract
BACKGROUND Coronary CT angiography (CCTA) is an excellent tool for noninvasive assessment of coronary arteries in low- to intermediate-risk individuals. However, the accuracy of CCTA heavily depends on image quality. Our objective was to develop and validate a tool to predict pre-CCTA risk of obtaining an uninterpretable result in symptomatic patients. METHODS AND RESULTS Among 8585 symptomatic patients, we identified variables independently associated with the presence of at least 1 uninterpretable major coronary segment to create the uninterpretable risk score (URS). This risk score was developed using both clinical variables and patient variables acquired at the time the CCTA was performed (heart rate and coronary calcium). The URS was then prospectively validated among an additional 915 symptomatic patients. The URS was predictive of uninterpretable results in both the development and the validation cohorts. For every 4-point increase in the URS (range, 0 to 12), the rate of at least 1 uninterpretable coronary segment per 100 CCTA studies increased ≈1.5 fold. Increased heart rate and coronary artery calcium score were predictive of uninterpretable CCTA study results. Uninterpretable results were associated with 3-month outcomes in the development cohort. CONCLUSIONS The URS can categorize patients who are likely to have at least 1 uninterpretable major coronary segment on CCTA. This may aid in appropriate patient selection for CCTA and avoiding radiation exposure in those likely to have an uninterpretable study. Clinical Trial Registration- URL: http:///www.clinicaltrials.gov. Unique identifier: NCT00640068.
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Hybrid retinal image registration.
Chanwimaluang, T, Fan, G, Fransen, SR
IEEE transactions on information technology in biomedicine : a publication of the IEEE Engineering in Medicine and Biology Society. 2006;(1):129-42
Abstract
This work studies retinal image registration in the context of the National Institutes of Health (NIH) Early Treatment Diabetic Retinopathy Study (ETDRS) standard. The ETDRS imaging protocol specifies seven fields of each retina and presents three major challenges for the image registration task. First, small overlaps between adjacent fields lead to inadequate landmark points for feature-based methods. Second, the non-uniform contrast/intensity distributions due to imperfect data acquisition will deteriorate the performance of area-based techniques. Third, high-resolution images contain large homogeneous nonvascular/texureless regions that weaken the capabilities of both feature-based and area-based techniques. In this work, we propose a hybrid retinal image registration approach for ETDRS images that effectively combines both area-based and feature-based methods. Four major steps are involved. First, the vascular tree is extracted by using an efficient local entropy-based thresholding technique. Next, zeroth-order translation is estimated by maximizing mutual information based on the binary image pair (area-based). Then image quality assessment regarding the ETDRS field definition is performed based on the translation model. If the image pair is accepted, higher-order transformations will be involved. Specifically, we use two types of features, landmark points and sampling points, for affine/quadratic model estimation. Three empirical conditions are derived experimentally to control the algorithm progress, so that we can achieve the lowest registration error and the highest success rate. Simulation results on 504 pairs of ETDRS images show the effectiveness and robustness of the proposed algorithm.
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Is there a change in water proton density associated with functional magnetic resonance imaging?
Jochimsen, TH, Norris, DG, Möller, HE
Magnetic resonance in medicine. 2005;(2):470-3
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Abstract
In a recent series of studies (see, for example, Stroman et al. Magn Reson Imag 2001; 19:827-831), an increase of water proton density has been suggested to correlate with neuronal activity. Owing to the significant implications of such a mechanism for other functional experiments, the functional signal changes in humans at very short echo times were re-examined by spin-echo EPI at 3 T. The results do not confirm the previous hypothesis of a significant increase in extravascular proton density at TE = 0. Instead, an alternative explanation of the effect is offered: The use of a low threshold to identify activated voxels may generate an artificial offset in functional contrast due to the inclusion of false-positives in the analysis.
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Automatic detection of red lesions in digital color fundus photographs.
Niemeijer, M, van Ginneken, B, Staal, J, Suttorp-Schulten, MS, Abràmoff, MD
IEEE transactions on medical imaging. 2005;(5):584-92
Abstract
The robust detection of red lesions in digital color fundus photographs is a critical step in the development of automated screening systems for diabetic retinopathy. In this paper, a novel red lesion detection method is presented based on a hybrid approach, combining prior works by Spencer et al. (1996) and Frame et al. (1998) with two important new contributions. The first contribution is a new red lesion candidate detection system based on pixel classification. Using this technique, vasculature and red lesions are separated from the background of the image. After removal of the connected vasculature the remaining objects are considered possible red lesions. Second, an extensive number of new features are added to those proposed by Spencer-Frame. The detected candidate objects are classified using all features and a k-nearest neighbor classifier. An extensive evaluation was performed on a test set composed of images representative of those normally found in a screening set. When determining whether an image contains red lesions the system achieves a sensitivity of 100% at a specificity of 87%. The method is compared with several different automatic systems and is shown to outperform them all. Performance is close to that of a human expert examining the images for the presence of red lesions.