Hina Arif-Tiwari

A Systematic Review and Meta-Analysis of Diagnostic Performance of MRI for Evaluation of Acute Appendicitis

OBJECTIVE A meta-analysis was performed to determine the accuracy of MRI in the diagnosis of acute appendicitis in the general population and in subsets of pregnant patients and children. MATERIALS AND METHODS A systematic search of the PubMed and EMBASE databases for articles published through the end of October 2014 was performed to identify studies that used MRI to evaluate patients suspected of having acute appendicitis. Pooled data for sensitivity, specificity, and positive and negative predictive values were calculated. RESULTS A total of 30 studies that comprised 2665 patients were reviewed. The sensitivity and specificity of MRI for the diagnosis of acute appendicitis are 96% (95% CI, 95-97%) and 96% (95% CI, 95-97%), respectively. In a subgroup of studies that focused solely on pregnant patients, the sensitivity and specificity of MRI were 94% (95% CI, 87-98%) and 97% (95% CI, 96-98%), respectively, whereas in studies that focused on children, sensitivity and specificity were found to be 96% (95% CI, 95-97%) and 96% (95% CI, 94-98%), respectively. CONCLUSION MRI has a high accuracy for the diagnosis of acute appendicitis, for a wide range of patients, and may be acceptable for use as a first-line diagnostic test.

MRI of hepatocellular carcinoma: An update of current practices

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and liver transplantation is the optimal treatment for selected patients with HCC and chronic liver disease (CLD). Accurate selection of patients for transplantation is essential to maximize patient outcomes and ensure optimized allocation of donor organs. Magnetic resonance imaging (MRI) is a powerful tool for the detection, characterization, and staging of HCC. In patients with CLD, the MRI findings of an arterial-enhancing mass with subsequent washout and enhancing capsule on delayed interstitial phase images are diagnostic for HCC. Major organizations with oversight for organ donor distribution, such as The Organ Procurement and Transplantation Network (OPTN), accept an imaging diagnosis of HCC, no longer requiring tissue biopsy. In patients that are awaiting transplantation, or are not candidates for liver transplantation, localized therapies such as transarterial chemoembolization and radiofrequency ablation may be offered. MRI can be used to monitor treatment response. The purpose of this review article is to describe the role of imaging methods in the diagnosis, staging, and follow-up of HCC, with particular emphasis on established and evolving MRI techniques employing nonspecific gadolinium chelates, hepatobiliary contrast agents, and diffusion weighted imaging. We also briefly review the recently developed Liver Imaging Reporting and Data System (LI-RADS) formulating a standardized terminology and reporting structure for evaluation of lesions detected in patients with CLD.

Accuracy of Unenhanced MR Imaging in the Detection of Acute Appendicitis: Single-Institution Clinical Performance Review

PURPOSE To determine the accuracy of unenhanced magnetic resonance (MR) imaging in the detection of acute appendicitis in patients younger than 50 years who present to the emergency department with right lower quadrant (RLQ) pain. MATERIALS AND METHODS The institutional review board approved this retrospective study of 403 patients from August 1, 2012, to July 30, 2014, and waived the informed consent requirement. A cross-department strategy was instituted to use MR imaging as the primary diagnostic modality in patients aged 3-49 years who presented to the emergency department with RLQ pain. All MR examinations were performed with a 1.5- or 3.0-T system. Images were acquired without breath holding by using multiplanar half-Fourier single-shot T2-weighted imaging without and with spectral adiabatic inversion recovery fat suppression without oral or intravenous contrast material. MR imaging room time was measured for each patient. Prospective image interpretations from clinical records were reviewed to document acute appendicitis or other causes of abdominal pain. Final clinical outcomes were determined by using (a) surgical results (n = 77), (b) telephone follow-up combined with review of the patients medical records (n = 291), or (c) consensus expert panel assessment if no follow-up data were available (n = 35). Logistic regression analysis was performed to evaluate the sensitivity and specificity of MR imaging in the detection of acute appendicitis, and corresponding 95% confidence intervals were determined. RESULTS Of the 403 patients, 67 had MR imaging findings that were positive for acute appendicitis, and 336 had negative findings. MR imaging had a sensitivity of 97.0% (65 of 67) and a specificity of 99.4% (334 of 336). The mean total room time was 14 minutes (range, 8-62 minutes). An alternate diagnosis was offered in 173 (51.5%) of 336 patients. CONCLUSION MR imaging is a highly sensitive and specific test in the evaluation of patients younger than 50 years with acute RLQ pain that uses a rapid imaging protocol performed without intravenous or oral contrast material.

MRI of diffuse liver disease: the common and uncommon etiologies.

Diffuse liver disease, including all causes of chronic liver disease, affects tens of millions of people worldwide. There is a growing need for diagnostic evaluation as treatments become more readily available, particularly for viral liver disease. Magnetic resonance imaging (MRI) provides unique capabilities for noninvasive characterization of liver tissue that rival or surpass the diagnostic utility of liver biopsies. There has been incremental improvement in the use of standardized MRI sequences, acquired before and after administration of contrast for the evaluation of diffuse liver disease, and this includes study of the liver parenchyma and blood supply. More recent developments have led to methods for quantifying important liver metabolites, including fat and iron, and liver fibrosis, which is the hallmark for chronic liver disease. In this study, we review the MRI techniques and diagnostic features associated with common and uncommon etiologies of diffuse liver diseases, including processes that lead to abnormal perfusion (e.g. Budd-Chiari syndrome, congestive hepatomegaly), deposition diseases (e.g. fatty liver, hemochromatosis, Wilsons disease), and abnormalities that are related to inflammation and fibrosis (e.g. primary sclerosing cholangitis, sarcoidosis).

Differentiation of lipid-poor adrenal adenomas from non-adenomas with magnetic resonance imaging: Utility of dynamic, contrast enhancement and single-shot T2-weighted sequences

PURPOSE To evaluate the utility of dynamic, contrast-enhanced magnetic resonance imaging (MRI) in combination with single-shot T2-weighted (ssT2) sequences in the differentiation of lipid-poor adrenal adenomas from non-adenomas. MATERIALS AND METHODS This retrospective study was approved by the institutional review board and is HIPAA compliant. Between January 2007 and December 2010, 46 patients with MRI demonstrating a lipid-poor adrenal lesion who underwent either surgical resection or a minimum of 24 months of imaging follow-up were identified retrospectively. All images were retrospectively reviewed in blinded fashion by two radiologists. Each adrenal lesion was categorized by dynamic enhancement features and qualitative signal on ssT2 images and was categorized as an adenoma if it demonstrated homogenous enhancement in the arterial phase, washout with capsule enhancement in the delayed phase, and T2 signal isointense to normal adrenal tissue. Any lesion that did not fulfill all the criteria was classified as a non-adenoma. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for characterization of adenoma were calculated for each reader with 95% confidence intervals. A κ test assessed level of agreement between readers. RESULTS Application of our criteria lead to an MRI diagnosis of lipid-poor adrenal adenoma with a sensitivity of 84.2-89.5% (16/19-17/19), specificity of 96.3% (26/27), positive predictive value of 94.1-94.4% (16/17-17/18), negative predictive value of 89.7-92.9% (26/29-26/28), and accuracy of 91.3-93.5% (42/46-43/46). Agreement between the two readers showed substantial κ agreement for the differentiation of adenoma from non-adenoma. CONCLUSIONS Dynamic, contrast-enhanced T1-weighted three-dimensional gradient echo sequences in combination with ssT2 images can accurately differentiate lipid-poor adrenal adenomas from non-adenomas.

MRI of diffuse liver disease: characteristics of acute and chronic diseases

Diffuse liver disease, including chronic liver disease, affects tens of millions of people worldwide, and there is a growing need for diagnostic evaluation as treatments become more readily available, particularly for viral liver diseases. Magnetic resonance imaging (MRI) provides unique capabilities for noninvasive characterization of the liver tissue that rival or surpass the diagnostic utility of liver biopsies. There has been incremental improvement in the use of standardized MRI sequences, acquired before and after administration of a contrast agent, for the evaluation of diffuse liver disease and the study of the liver parenchyma and blood supply. More recent developments have led to methods for quantifying important liver metabolites, including lipids and iron, and liver fibrosis, the hallmark of chronic liver disease. Here, we review the MRI techniques and diagnostic features associated with acute and chronic liver disease.

MRI of ovarian torsion: Correlation of imaging features with the presence of perifollicular hemorrhage and ovarian viability

PURPOSE The purpose of our study is to test for: (a) correlation between the presence of a perifollicular T2-hypointense rim on MRI with the presence of perifollicular hemorrhage on histology; and (b) correlation between this finding and diminished ovarian viability after intra-operative detorsion. METHODS AND MATERIALS Our IRB-approved, retrospective study evaluated 780 patients between August 2012 and February 2016 with ovarian torsion as a diagnostic consideration on the emergency department note. Patients were included if they had preoperative MRI and intraoperatively confirmed case of ovarian torsion. MRIs were retrospectively reviewed for presence of perifollicular T2 hypointense rim in the torsed ovary. Two arms of analysis were performed: (a) assessment of perifollicular hemorrhage on histological exam; and (b) assessment of ovarian viability after intra-operative detorsion. Sensitivity, specificity, positive predictive value, and negative predictive value of MRI for predicting ovarian viability in the setting of torsion was performed. κ test assessed level of agreement between readers. RESULTS 24 patients included in one of the two arms; 20 in viability analysis and 12 in perifollicular hemorrhage analysis (8 in both). The presence of T2-hypointense rim on MRI demonstrated 88.9% sensitivity and 66.7% specificity for the diagnosis of perifollicular hemorrhage on histology, and 91.7% sensitivity and 100% specificity for predicting intraoperative viability. CONCLUSION The presence of a perifollicular T2 hypointense rim on MRI in the setting of ovarian torsion correlates with perifollicular hemorrhage on histopathologic exam, and may also be a useful predictor of ovarian viability in patients presenting with ovarian torsion.

Advances in Lower Extremity Ultrasound

AbstractDiagnostic ultrasound techniques used in the evaluation of the musculoskeletal system are rapidly evolving. Conventional B-mode and Doppler ultrasound imaging methods are workhorses in the diagnosis and treatment decision making for traumatic and pathologic conditions of joints, tendons, muscles, ligaments, and peripheral nerves. Recently developed sonoelastography techniques enable the qualitative and quantitative evaluation of the material properties of musculoskeletal tissues . The recent availability of sonoelastography on clinical machines will facilitate its progressive utilization in routine clinical practice. Exciting new developments in ultrasound imaging enable real-time fusion with imported magnetic resonance or computed tomography images, facilitating ultrasound-guided interventional procedures and teaching of ultrasound anatomy to trainees. In this review article, the authors discuss new advances in sonoelastography of the lower extremity with emphasis on shear wave imaging and briefly the exciting features of ultrasound fusion imaging with computed tomography and magnetic resonance imaging.

Improved Detection of Pelvic Organ Prolapse: Comparative Utility of Defecography Phase Sequence to Nondefecography Valsalva Maneuvers in Dynamic Pelvic Floor Magnetic Resonance Imaging

PURPOSE To evaluate the utility of a defecography phase (DP) sequence in dynamic pelvic floor MRI (DPMRI), in comparison to DPMRI utilizing only non-defecography Valsalva maneuvers (VM). MATERIALS AND METHODS Inclusion criteria identified 237 female patients with symptoms and/or physical exam findings of pelvic floor prolapse. All DPMRI exams were obtained following insertion of ultrasound gel into the rectum and vagina. Steady-state free-precession sequences in sagittal plane were acquired in the resting state, followed by dynamic cine acquisitions during VM and DP. In all phases, two experienced radiologists performed blinded review using the H-line, M-line, Organ prolapse (HMO) system. The presence of a rectocele, enterocele and inferior descent of the anorectal junction, bladder base, and vaginal vault were recorded in all patients using the pubococcygeal line as a fixed landmark. RESULTS DPMRI with DP detected significantly more number of patients than VM (p<0.0001) with vaginal prolapse (231/237, 97.5% vs. 177/237, 74.7%), anorectal prolapse (227/237, 95.8% vs. 197/237, 83.1%), cystocele (197/237, 83.1% vs. 108/237, 45.6%), and rectocele (154/237, 65% vs. 93/237, 39.2%). The median cycstocele (3.2cm vs. 1cm), vaginal prolapse (3cm vs. 1.5cm), anorectal prolapse (5.4cm vs. 4.2cm), H-line (8cm vs. 7.2cm) and M-line (5.3cm vs. 3.9cm) were significantly higher with DP than VM (p<0.0001). CONCLUSIONS Addition of DP to DPMRI demonstrates a greater degree of pelvic floor instability as compared to imaging performed during VM alone. Pelvic floor structures may show mild descent or appear normal during VM, with marked prolapse on subsequent DP images.