Mahan Mathur

Fungal Infections of the Central Nervous System

Fungal infections of the central nervous system (CNS) frequently occur in the immunocompromised or debilitated host. Imaging findings are non-specific but may be organized into extra-axial, parenchymal, and vascular categories. Furthermore, knowledge of fungal morphology may predict the imaging manifestations with large, hyphal species having a predilection for brain parenchymal involvement, while small, unicellular organisms typically result in meningitis. Advanced imaging techniques such as diffusion-weighted imaging, MR perfusion and MR spectroscopy, when combined with clinical findings, may help in differentiating fungal disease from other mimckers such as pyogenic infection or cystic metastases.

Pelvic Inflammatory Disease: Multimodality Imaging Approach with Clinical-Pathologic Correlation.

Pelvic inflammatory disease (PID) is a common medical problem, with almost 1 million cases diagnosed annually. Historically, PID has been a clinical diagnosis supplemented with the findings from ultrasonography (US) or magnetic resonance (MR) imaging. However, the diagnosis of PID can be challenging because the clinical manifestations may mimic those of other pelvic and abdominal processes. Given the nonspecific clinical manifestations, computed tomography (CT) is commonly the first imaging examination performed. General CT findings of early- and late-stage PID include thickening of the uterosacral ligaments, pelvic fat stranding with obscuration of fascial planes, reactive lymphadenopathy, and pelvic free fluid. Recognition of these findings, as well as those seen with cervicitis, endometritis, acute salpingitis, oophoritis, pyosalpinx, hydrosalpinx, tubo-ovarian abscess, and pyometra, is crucial in allowing prompt and accurate diagnosis. Late complications of PID include tubal damage resulting in infertility and ectopic pregnancy, peritonitis caused by uterine and/or tubo-ovarian abscess rupture, development of peritoneal adhesions resulting in bowel obstruction and/or hydroureteronephrosis, right upper abdominal inflammation (Fitz-Hugh-Curtis syndrome), and septic thrombophlebitis. Recognition of these late manifestations at CT can also aid in proper patient management. At CT, careful assessment of common PID mimics, such as endometriosis, adnexal torsion, ruptured hemorrhagic ovarian cyst, adnexal neoplasms, appendicitis, and diverticulitis, is important to avoid misinterpretation, delay in management, and unnecessary surgery. Correlation with the findings from complementary imaging examinations, such as US and MR imaging, is useful for establishing a definitive diagnosis. (©)RSNA, 2016.

Homogeneous T1 Hyperintense Renal Lesions with Smooth Borders: Is Contrast-enhanced MR Imaging Needed?

Purpose To retrospectively determine if homogeneous high T1 signal intensity (SI) masses with smooth borders on unenhanced magnetic resonance (MR) images can be characterized as benign. Materials and Methods Institutional review board approval was obtained for this HIPAA-compliant retrospective study, with waiver of informed consent. MR images in 84 patients with hemorrhagic or proteinaceous cysts and 50 patients with renal cell carcinoma (RCC) were evaluated. Sixty-three cysts and 49 RCCs underwent unenhanced computed tomography (CT). SI ratio and CT attenuation were determined. Two radiologists evaluated lesions as follows: score 1, homogeneous with smooth borders; score 2, mildly heterogeneous with mildly lobulated borders; score 3, moderately heterogeneous and irregular borders; and score 4, markedly heterogeneous with markedly irregular borders. Statistical analysis was performed by using multivariable logistic regression, Welch t test, Z test, Fisher-exact test, Shapiro-Wilk test, and receiver operating characteristic curve analysis. A diagnostic criterion was formulated by using classification and regression tree analysis. Results SI ratio and attenuation of hemorrhagic or proteinaceous cysts were significantly higher than those of RCCs (SI ratio: cyst 2.4 ± 0.8, RCC 1.5 ± 0.3; attenuation: cyst 51.9 ± 21.5, RCC: 34.8 ± 10.0). Reader 1 scored morphology of 68 (81%) hemorrhagic or proteinaceous cysts as score 1 on MR images and as score 45 (71%) on CT scans. Reader 2 scored morphology of 59 (70%) hemorrhagic or proteinaceous cysts as score 1 on MR images and as score 43 (68%) on CT scans. Two-step classification tree suggested that homogeneous high T1 SI lesions with smooth borders and SI ratio of greater than 1.6 predict the lesion as benign cysts. Similar algorithm for CT suggested threshold of 51 HU. Increasing threshold to 2.5 for SI ratio and 66 for Hounsfield units resulted in 99.9% confidence for characterizing benign cysts. Conclusion The retrospective assessment shows that morphologic assessment and SI quantification on unenhanced T1-weighted MR images can be used to differentiate benign hemorrhagic or proteinaceous cysts from RCC, although prospective assessment will be needed to confirm these results. (©) RSNA, 2016.

Standards for MRI reporting—the evolution to PI-RADS v 2.0

Prostate cancer (PCa) remains a leading cause of death in the United States, but the vast majority of men diagnosed with PCa will die from other causes. While historically the capability of assessing the risk of life-threatening versus indolent PCa has relied heavily on serum prostate-specific antigen (PSA) and transrectal ultrasound (TRUS), multiparametric magnetic resonance imaging (mpMRI) has emerged as the leading tool for detection and characterization of clinically significant PCa. However, wide variations and lack of standardization of mpMRI data acquisition, interpretation, and reporting have hampered its progress. The development of a set of consensus guidelines, initially called Prostate Imaging and Reporting and Data System (PI-RADS) and eventually updated to a document called PI-RADS v2 has attempted to solve these shortcomings. As it stands, PI-RADS v2 currently represents the most up-to-date information on how to acquire, interpret, and report mpMRI of the prostate.

Case 13-2014: A 41-year-old man with fever and abdominal pain after stem-cell transplantation

From the Department of Infectious Diseases, M.D. Anderson Cancer Center, Houston (D.P.K.); and the Department of Radiology (M.M.), the Division of Hematology–Oncology, Department of Medicine (Y.-B.C.), and the Departments of Surgery (P.C.S.) and Pathology (J.Y.T.), Massachusetts General Hospital, and the Departments of Radiology (M.M.), Medicine (Y.-B.C.), Surgery (P.C.S.), and Pathology (J.Y.T.), Harvard Medical School — both in Boston.

Case 13-2014

From the Department of Infectious Diseases, M.D. Anderson Cancer Center, Houston (D.P.K.); and the Department of Radiology (M.M.), the Division of Hematology–Oncology, Department of Medicine (Y.-B.C.), and the Departments of Surgery (P.C.S.) and Pathology (J.Y.T.), Massachusetts General Hospital, and the Departments of Radiology (M.M.), Medicine (Y.-B.C.), Surgery (P.C.S.), and Pathology (J.Y.T.), Harvard Medical School — both in Boston.

Utility of Magnetic Resonance Imaging in the Evaluation of Intraoperatively Confirmed Pelvic Adhesions.

Objective The aim of this study was to evaluate the ability of magnetic resonance imaging (MRI) to identify pelvic adhesions. Design This was an institutional review board–approved retrospective analysis. Methods Ninety-nine patients met inclusion criteria and constituted our study population. Inclusion criteria: patients who underwent MRI and subsequent gynecologic abdominal surgery within 6 months after MRI. All imaging and operative reports were reviewed for the presence of pelvic adhesions by independent and blinded specialists. The findings were compared to calculate MRI sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in the evaluation of pelvic adhesions. Results The specificity of MRI in the detection of pelvic adhesions was greater than 90% in all locations with the exception of the posterior cul-de-sac. Accuracy was highest in the anterior cul-de-sac at 88%. The positive predictive value was greater than 85% for prediction of non–location-specific adhesions. Conclusions Magnetic resonance imaging is very specific in the evaluation of pelvic adhesions.

Imaging Redundancy in Screening for Abdominal Aortic Aneurysm

DESCRIPTION OF THE PROBLEM Overuse of imaging is increasingly recognized as a source of excessive health care spending in the United States, where it has been estimated that 20% to 50% of radiologic tests are unnecessary [1]. In particular, prior studies have demonstrated that the use of ultrasound to screen for abdominal aortic aneurysm (AAA) is frequently redundant, as many patients have undergone previous radiologic tests that visualize the abdominal aorta and are sufficient for screening [2,3]. The US Preventive Services Task Force and American Heart Association recommend that all men aged 65 to 75 years who are prior or current smokers undergo abdominal ultrasound to rule out AAA [2-6]. As a single lifetime screening, AAA ultrasound can provide valuable insights in understanding imaging overutilization. However, two prior studies that reported on AAA ultrasound redundancy were not designed specifically to investigate this particular problem and were limited because imaging and radiology reports were not reviewed; and inclusion criteria were somewhat arbitrary. Hye et al [2] performed a database search and reported that 48.3% of patients aged 65 to 75 years eligible for AAA screening had undergone prior

Imaging patients with renal impairment

Abstract Imaging with intravascular contrast media is generally considered safe, particularly in patients without renal failure. However, as renal function deteriorates, the potential risk of nonallergic-type adverse events increases. This presents a unique challenge, particularly when the use of intravenous contrast media is deemed essential for diagnostic purposes. Following a discussion regarding the definition and epidemiology of kidney injury, this review focuses on the evolving understanding of both contrast-induced nephropathy and nephrogenic systemic fibrosis and discusses preventative strategies aimed at minimizing the risk of developing these entities. Alternative non-contrast imaging techniques are also discussed.

MRI-Ultrasound Fusion Targeted Biopsy of Prostate Imaging Reporting and Data System Version 2 Category 5 Lesions Found False-Positive at Multiparametric Prostate MRI

OBJECTIVE The purpose of this study was to determine imaging and clinical features associated with Prostate Imaging Reporting and Data System (PI-RADS) category 5 lesions identified prospectively at multiparametric MRI (mpMRI) that were found benign at MRI-ultrasound fusion targeted biopsy. MATERIALS AND METHODS Between January 2015 and July 2016, 325 men underwent prostate mpMRI followed by MRI-ultrasound fusion targeted biopsy of 420 lesions prospectively identified and assessed with PI-RADS version 2. The frequency of clinically significant prostate cancer (defined as Gleason score ≥ 7) among PI-RADS 5 lesions was determined. Lesions with benign pathologic results were retrospectively reassessed by three abdominal radiologists and categorized as concordant or discordant between mpMRI and biopsy results. Multivariate logistic regression was used to identify factors associated with benign disease. Bonferroni correction was used. RESULTS Of the 98 PI-RADS 5 lesions identified in 89 patients, 18% (18/98) were benign, 10% (10/98) were Gleason 6 disease, and 71% (70/98) were clinically significant prostate cancer. Factors associated with benign disease at multivariate analysis were lower prostate-specific antigen density (odds ratio [OR], 0.88; p < 0.001) and apex (OR, 3.54; p = 0.001) or base (OR, 7.11; p = 0.012) location. On secondary review of the 18 lesions with benign pathologic results, 39% (7/18) were scored as benign prostatic hyperplasia nodules, 28% (5/18) as inflammatory changes, 5% (1/18) as normal anatomic structures, and 28% (5/18) as discordant with imaging findings. CONCLUSION PI-RADS 5 lesions identified during routine clinical interpretation are associated with a high risk of clinically significant prostate cancer. A benign pathologic result was significantly correlated with lower prostate-specific antigen density and apex or base location and most commonly attributed to a benign prostatic hyperplasia nodule. Integration of these clinical features may improve the interpretation of high-risk lesions identified with mpMRI.