Zarine K. Shah

Amide proton transfer MR imaging of prostate cancer: A preliminary study

To evaluate the capability of amide proton transfer (APT) MR imaging for detection of prostate cancer that typically shows a higher tumor cell proliferation rate and cellular density leading to an MRI‐detectable overall elevated mobile protein level in higher grade tumors.

Radiology of pancreatic adenocarcinoma: Current status of imaging

Pancreatic adenocarcinoma is one of the leading causes of cancer death in the West, with a poor overall 5‐year survival rate of only 4%. Late clinical presentation with an advanced disease results in a low rate of surgical intervention. Tumor serum marker CA 19‐9 is sensitive, although not specific for the diagnosis of adenocarcinomas of the pancreas. The treatment approach is based on whether the tumor is resectable or non‐resectable at presentation. Therefore, imaging plays a crucial role in the management of this disease. Many modalities are available to image the pancreas. They include non‐invasive techniques, like ultrasound, contrast‐enhanced multidetector computed tomography, magnetic resonance imaging and integrated positron emission tomography/computed tomography, and invasive techniques, like endoscopic retrograde cholangiopancreatography and endoscopic ultrasound. Each of these modalities has its peculiar strengths and weaknesses.

Enhancing and Expansile Portal Vein Thrombosis: Value in the Diagnosis of Hepatocellular Carcinoma in Patients with Multiple Hepatic Lesions

OBJECTIVE The objective of this study was to determine whether the presence of enhancing and expansile portal vein thrombus is suggestive of the diagnosis of hepatocellular carcinoma. CONCLUSION In the presence of hepatic tumors, enhancing expansile portal vein thrombus is highly suggestive of hepatocellular carcinoma.

Performance Comparison of 1.5-T Endorectal Coil MRI with 3.0-T Nonendorectal Coil MRI in Patients with Prostate Cancer

RATIONALE AND OBJECTIVES To compare prostate morphology, image quality, and diagnostic performance of 1.5-T endorectal coil magnetic resonance (MR) imaging (MRI) and 3.0-T nonendorectal coil MRI in patients with prostate cancer. MATERIALS AND METHODS MR images obtained of 83 patients with prostate cancer using 1.5-T MRI systems with an endorectal coil were compared to images collected from 83 patients with a 3.0-T MRI system. Prostate diameters were measured, and image quality was evaluated by one American Board of Radiology (ABR)-certified radiologist (reader 1) and one ABR-certified diagnostic medical physicist (reader 2). The likelihood of the presence of peripheral zone cancer in each sextant and local extent was rated and compared to histopathologic findings. RESULTS Prostate anterior-posterior diameter measured by both readers was significantly shorter with 1.5-T endorectal MRI than with 3.0-T MRI. The overall image quality score difference was significant only for reader 1. Both readers found that the two MRI systems provided a similar diagnostic accuracy in cancer localization, extraprostatic extension, and seminal vesicle involvement. CONCLUSIONS Nonendorectal coil 3.0-T MRI provides prostate images that are natural in shape and that have comparable image quality to those obtained at 1.5 T with an endorectal coil, but not superior diagnostic performance. These findings suggest an opportunity exists for improving technical aspects of the 3.0-T prostate MRI.

Prediction of chemotherapeutic response in bladder cancer using K-means clustering of dynamic contrast-enhanced (DCE)-MRI pharmacokinetic parameters.

To apply k‐means clustering of two pharmacokinetic parameters derived from 3T dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) to predict the chemotherapeutic response in bladder cancer at the mid‐cycle timepoint.

Quantification of liver fat

Fat accumulation in the liver causes metabolic diseases such as obesity, hypertension, diabetes or dyslipidemia by affecting insulin resistance, and increasing the risk of cardiac complications and cardiovascular disease mortality. Fatty liver diseases are often reversible in their early stage; therefore, there is a recognized need to detect their presence and to assess its severity to recognize fat-related functional abnormalities in the liver. This is crucial in evaluating living liver donors prior to transplantation because fat content in the liver can change liver regeneration in the recipient and donor. There are several methods to diagnose fatty liver, measure the amount of fat, and to classify and stage liver diseases (e.g. hepatic steatosis, steatohepatitis, fibrosis and cirrhosis): biopsy (the gold-standard procedure), clinical (medical physics based) and image analysis (semi or fully automated approaches). Liver biopsy has many drawbacks: it is invasive, inappropriate for monitoring (i.e., repeated evaluation), and assessment of steatosis is somewhat subjective. Qualitative biomarkers are mostly insufficient for accurate detection since fat has to be quantified by a varying threshold to measure disease severity. Therefore, a quantitative biomarker is required for detection of steatosis, accurate measurement of severity of diseases, clinical decision-making, prognosis and longitudinal monitoring of therapy. This study presents a comprehensive review of both clinical and automated image analysis based approaches to quantify liver fat and evaluate fatty liver diseases from different medical imaging modalities.

Validation of diagnostic characteristics of needle based confocal laser endomicroscopy in differentiation of pancreatic cystic lesions

Background and aims: Endoscopic ultrasound (EUS)-guided needle-based Confocal Laser Endomicroscopy (nCLE) characteristics of pancreatic cystic lesions (PCLs) have been identified in studies where the gold standard surgical histopathology was available in a minority of patients. There are diverging reports of interobserver agreement (IOA) and paucity of intraobserver reliability (IOR). Thus, we sought to validate current EUS-nCLE criteria of PCLs in a larger consecutive series of surgical patients. Methods: A retrospective analysis of patients who underwent EUS-nCLE at a single center was performed. For calculation of IOA (Fleiss’ kappa) and IOR (Cohen’s kappa), blinded nCLE-naïve observers (n = 6) reviewed nCLE videos of PCLs in two phases separated by a 2-week washout period. Results: EUS-nCLE was performed in 49 subjects, and a definitive diagnosis was available in 26 patients. The overall sensitivity, specificity, and accuracy for diagnosing a mucinous PCL were 94 %, 82 %, and 89 %, respectively. The IOA for differentiating mucinous vs. non-mucinous PCL was “substantial” (κ = 0.67, 95 %CI 0.57, 0.77). The mean (± standard deviation) IOR was “substantial” (κ = 0.78 ± 0.13) for diagnosing mucinous PCLs. Both the IOAs and mean IORs were “substantial” for detection of known nCLE image patterns of papillae/epithelial bands of mucinous PCLs (IOA κ = 0.63; IOR κ = 0.76 ± 0.11), bright particles on a dark background of pseudocysts (IOA κ = 0.71; IOR κ = 0.78 ± 0.12), and fern-pattern or superficial vascular network of serous cystadenomas (IOA κ = 0.62; IOR κ = 0.68 ± 0.20). Three (6.1 % of 49) patients developed post-fine needle aspiration (FNA) pancreatitis. Conclusion: Characteristic EUS-nCLE patterns can be consistently identified and improve the diagnostic accuracy of PCLs. These results support further investigations to optimize EUS-nCLE while minimizing adverse events. Study registration: NCT02516488

Improving bladder cancer imaging using 3-T functional dynamic contrast-enhanced magnetic resonance imaging.

ObjectivesThe objective of this study was to assess the capability of T2-weighted magnetic resonance imaging (T2W-MRI) and the additional diagnostic value of dynamic contrast-enhanced MRI (DCE-MRI) using multitransmit 3 T in the localization of bladder cancer. Materials and MethodsThis prospective study was approved by the local institutional review board. Thirty-six patients were included in the study and provided informed consent. Magnetic resonance imaging scans were performed with T2W-MRI and DCE-MRI on a 3-T multitransmit system. Two observers (with 12 and 25 years of experience) independently interpreted T2W-MRI before DCE-MRI data (maps of pharmacokinetic parameters) to localize bladder tumors. The pathological examination of cystectomy bladder specimens was used as a reference criteria standard. The McNemar test was performed to evaluate the differences in sensitivity, specificity, and accuracy. Scores of &kgr; were calculated to assess interobserver agreement. ResultsThe sensitivity, specificity, and accuracy of the localization with T2W-MRI alone were 81% (29/36), 63% (5/8), and 77% (34/44) for observer 1 and 72% (26/36), 63% (5/8), and 70% (31/44) for observer 2. With additional DCE-MRI available, these values were 92% (33/36), 75% (6/8), and 89% (39/44) for observer 1 and 92% (33/36), 63% (5/8), and 86% (38/44) for observer 2. Dynamic contrast-enhanced MRI significantly (P < 0.01) improved the sensitivity and accuracy for observer 2. For the 23 patients treated with chemotherapy, DCE-MRI also significantly (P < 0.02) improved the sensitivity and accuracy of bladder cancer localization with T2W-MRI alone for observer 2. Scores of &kgr; were 0.63 for T2W-MRI alone and 0.78 for additional DCE-MRI. Of 7 subcentimeter malignant tumors, 4 (57%) were identified on T2W images and 6 (86%) were identified on DCE maps. Of 11 malignant tumors within the bladder wall thickening, 6 (55%) were found on T2W images and 10 (91%) were found on DCE maps. ConclusionsCompared with conventional T2W-MRI alone, the addition of DCE-MRI improved interobserver agreement as well as the localization of small malignant tumors and those within bladder wall thickening.

Small bowel obstruction: the value of coronal reformatted images from 16-multidetector computed tomography--a clinicoradiological perspective.

Objectives: To assess performance of 16-multidetector computed tomography for small bowel obstruction with surgery as standard of reference. To assess the impact of coronal reformats on reader confidence, and to address management perspective and surgeons assessment of coronal images. Materials and Methods: 16-Multidetector computed tomography scans of 30 patients presenting with clinical features of small bowel obstruction were reviewed. Five-millimeter axial images and 2.5-mm coronal images were available for interpretation. All patients had subsequent surgery. Two blinded readers independently reviewed axial and then coronal and axial (combination) images for transition site, etiology, and complications. Reader confidence was scored on a 3-point scale. A single surgeon evaluated studies for adequacy of scans and usefulness of coronal images. Results: Results showed that the recorded accuracies were slightly higher for etiology, transition site, and complications using the combination data set; this reached statistical significance for etiology only (P = 0.08). There was no significant increase in scan evaluation time with addition of coronal images. Surgeon considered the coronal images more informative as compared with the axial images in 76.6% of cases. Conclusions: Coronal images generated at the scanner console are complementary to axials and improve reader confidence. Surgeons find coronal images more helpful than axial images for management.

Vessel segmentation from abdominal magnetic resonance images: adaptive and reconstructive approach.

The liver vessels, which have low signal and run next to brighter bile ducts, are difficult to segment from MR images. This study presents a fully automated and adaptive method to segment portal and hepatic veins on magnetic resonance images. In the proposed approach, segmentation of these vessels is achieved in four stages: (i) initial segmentation, (ii) refinement, (iii) reconstruction, and (iv) post-processing. In the initial segmentation stage, k-means clustering is used, the results of which are refined iteratively with linear contrast stretching algorithm in the next stage, generating a mask image. In the reconstruction stage, vessel regions are reconstructed with the marker image from the first stage and the mask image from the second stage. Experimental data sets include slices that show fat tissues, which have the same gray level values with vessels, outside the margin of the liver. These structures are removed in the last stage. Results show that the proposed approach is more efficient than other thresholding-based methods. Copyright