Effect of beam attenuation on muscle ultrasound echogenicity measurement in muscular dystrophies.

PURPOSE: In advanced muscular dystrophies (AMD), quantification of muscle echo-intensity (EI) may be influenced by ultrasound beam attenuation, due to fibrosis and fatty infiltration of muscle tissue. Objective of the study was to compare EI measurements using grayscale analysis between a superficial and whole-muscle region of interest (ROI) in subjects with advanced and mild-to-moderate muscular dystrophy (MMD). METHODS: Thirty-two adult subjects diagnosed with a muscular dystrophy and twenty-five matched healthy controls underwent ultrasound assessment of the biceps brachii (BB), rectus femoris (RF) and tibialis anterior (TA) muscles. Based on Heckmatt grading scale of muscles, two disease groups, an AMD (Heckmatt grades 3 or 4) and a MMD (Heckmatt grade 2), were analyzed. Superficial ROI was set as one-fourth of the whole-muscle area, located immediately below the superficial fascia and always inside muscle boundaries. RESULTS: Muscle EI was significantly higher in the superficial compared to whole-muscle ROI, in all evaluated muscle groups of AMD subjects (BB, p = 0.004/RF, p = 0.027/TA, p = 0.002). EI values in superficial ROIs, for individual muscle analysis using z-scores, were more representative in assessments of muscle abnormality in advanced stages of the disease course (Heckmatt grades 3 and 4). In MMD and healthy muscles, no statistical difference was found in EI measurements between the two ROI types. CONCLUSIONS: In AMD, selection of superficial ROI is better representative of changes in muscle texture, although caution should be exercised when comparing ROIs of different sizes.

Multi-parametric MRI lesion heterogeneity biomarkers for breast cancer diagnosis.

PURPOSE: To identify intra-lesion imaging heterogeneity biomarkers in multi-parametric Magnetic Resonance Imaging (mpMRI) for breast lesion diagnosis. METHODS: Dynamic Contrast Enhanced (DCE) and Diffusion Weighted Imaging (DWI) of 73 female patients, with 85 histologically verified breast lesions were acquired. Non-rigid multi-resolution registration was utilized to spatially align sequences. Four (4) DCE (2nd post-contrast frame, Initial-Enhancement, Post-Initial-Enhancement and Signal-Enhancement-Ratio) and one (1) DWI (Apparent-Diffusion-Coefficient) representations were analyzed, considering a representative lesion slice. 11 1st-order-statistics and 16 texture features (Gray-Level-Co-occurrence-Matrix (GLCM) and Gray-Level-Run-Length-Matrix (GLRLM) based) were derived from lesion segments, provided by Fuzzy C-Means segmentation, across the 5 representations, resulting in 135 features. Least-Absolute-Shrinkage and Selection-Operator (LASSO) regression was utilized to select optimal feature subsets, subsequently fed into 3 classification schemes: Logistic-Regression (LR), Random-Forest (RF), Support-Vector-Machine-Sequential-Minimal-Optimization (SVM-SMO), assessed with Receiver-Operating-Characteristic (ROC) analysis. RESULTS: LASSO regression resulted in 7, 6 and 7 features subsets from DCE, DWI and mpMRI, respectively. Best classification performance was obtained by the RF multi-parametric scheme (Area-Under-ROC-Curve, (AUC) ± Standard-Error (SE), AUC ± SE = 0.984 ± 0.025), as compared to DCE (AUC ± SE = 0.961 ± 0.030) and DWI (AUC ± SE = 0.938 ± 0.032) and statistically significantly higher as compared to DWI. The selected mpMRI feature subset highlights the significance of entropy (1st-order-statistics and 2nd-order-statistics (GLCM)) and percentile features extracted from 2nd post-contrast frame, PIE, SER maps and ADC map. CONCLUSION: Capturing breast intra-lesion heterogeneity, across mpMRI lesion segments with 1st-order-statistics and texture features (GLCM and GLRLM based), offers a valuable diagnostic tool for breast cancer.

Selecting registration schemes in case of interstitial lung disease follow-up in CT.

PURPOSE: Primary goal of this study is to select optimal registration schemes in the framework of interstitial lung disease (ILD) follow-up analysis in CT. METHODS: A set of 128 multiresolution schemes composed of multiresolution nonrigid and combinations of rigid and nonrigid registration schemes are evaluated, utilizing ten artificially warped ILD follow-up volumes, originating from ten clinical volumetric CT scans of ILD affected patients, to select candidate optimal schemes. Specifically, all combinations of four transformation models (three rigid: rigid, similarity, affine and one nonrigid: third order B-spline), four cost functions (sum-of-square distances, normalized correlation coefficient, mutual information, and normalized mutual information), four gradient descent optimizers (standard, regular step, adaptive stochastic, and finite difference), and two types of pyramids (recursive and Gaussian-smoothing) were considered. The selection process involves two stages. The first stage involves identification of schemes with deformation field singularities, according to the determinant of the Jacobian matrix. In the second stage, evaluation methodology is based on distance between corresponding landmark points in both normal lung parenchyma (NLP) and ILD affected regions. Statistical analysis was performed in order to select near optimal registration schemes per evaluation metric. Performance of the candidate registration schemes was verified on a case sample of ten clinical follow-up CT scans to obtain the selected registration schemes. RESULTS: By considering near optimal schemes common to all ranking lists, 16 out of 128 registration schemes were initially selected. These schemes obtained submillimeter registration accuracies in terms of average distance errors 0.18 ± 0.01 mm for NLP and 0.20 ± 0.01 mm for ILD, in case of artificially generated follow-up data. Registration accuracy in terms of average distance error in clinical follow-up data was in the range of 1.985-2.156 mm and 1.966-2.234 mm, for NLP and ILD affected regions, respectively, excluding schemes with statistically significant lower performance (Wilcoxon signed-ranks test, p < 0.05), resulting in 13 finally selected registration schemes. CONCLUSIONS: Selected registration schemes in case of ILD CT follow-up analysis indicate the significance of adaptive stochastic gradient descent optimizer, as well as the importance of combined rigid and nonrigid schemes providing high accuracy and time efficiency. The selected optimal deformable registration schemes are equivalent in terms of their accuracy and thus compatible in terms of their clinical outcome.

A critical view of the general public's awareness and physicians' opinion of the trends and potential pitfalls of genetic testing in Greece.

AIM: Progress in deciphering the functionality of the human genome sequence in the wake of technological advances in the field of genomic medicine have dramatically reduced the overall costs of genetic analysis, thereby facilitating the incorporation of genetic testing services into mainstream clinical practice. Although Greek genetic testing laboratories offer a variety of different genetic tests, relatively little is known about how either the general public or medical practitioners perceive genetic testing services. MATERIALS & METHODS: We have therefore performed a nationwide survey of the views of 1717 members of the general public, divided into three age groups, from all over Greece, and residing in both large and small cities and villages, in order to acquire a better understanding of how they perceive genetic testing. We also canvassed the opinions of 496 medical practitioners with regard to genetic testing services in a separate survey that addressed similar issues. RESULTS: Our subsequent analysis indicated that a large proportion of the general public is aware of the nature of DNA, genetic disorders and the potential benefits of genetic testing, although this proportion declines steadily with age. Furthermore, a large proportion of the interviewed individuals would be willing to undergo genetic testing even if the cost of analysis was not covered by healthcare insurance. However, a relatively small proportion of the general public has actually been advized to undergo genetic testing, either by relatives or physicians. Most physicians believe that the regulatory and legal framework that governs genetic testing services in Greece is rather weak. Interestingly, the vast majority of the general public strongly opposes direct-access genetic testing, and most would prefer referral from a physician than from a pharmacist. CONCLUSION: Overall, our results provide a critical evaluation of the views of the general public with regard to genetics and genetic testing services in Greece and should serve as a model for replication in other populations.