Gaurav Khatri

Utility of diffusion‐weighted MRI in distinguishing benign and malignant hepatic lesions

To evaluate apparent diffusion coefficient (ADC) values for characterization of a variety of focal liver lesions and specifically for differentiation of solid benign lesions (focal nodular hyperplasia [FNH] and adenomas) from solid malignant neoplasms (metastases and hepatocellular carcinoma [HCC]) in a large case series.

The functional significance of microRNA-145 in prostate cancer

Background:MicroRNAs (miRNAs) are small noncoding RNAs that have important roles in numerous cellular processes. Recent studies have shown aberrant expression of miRNAs in prostate cancer tissues and cell lines. On the basis of miRNA microarray data, we found that miR-145 is significantly downregulated in prostate cancer.Methods and results:We investigated the expression and functional significance of miR-145 in prostate cancer. The expression of miR-145 was low in all the prostate cell lines tested (PC3, LNCaP and DU145) compared with the normal cell line, PWR-1E, and in cancerous regions of human prostate tissue when compared with the matched adjacent normal. Overexpression of miR-145 in PC3-transfected cells resulted in increased apoptosis and an increase in cells in the G2/M phase, as detected by flow cytometry. Investigation of the mechanisms of inactivation of miR-145 through epigenetic pathways revealed significant DNA methylation of the miR-145 promoter region in prostate cancer cell lines. Microarray analyses of miR-145-overexpressing PC3 cells showed upregulation of the pro-apoptotic gene TNFSF10, which was confirmed by real-time PCR and western analysis.Conclusion:One of the genes significantly upregulated by miR-145 overexpression is the proapoptotic gene TNFSF10. Therefore, modulation of miR-145 may be an important therapeutic approach for the management of prostate cancer.

Subtraction Imaging: Applications for Nonvascular Abdominal MRI

OBJECTIVE In this article we will illustrate the role of subtraction imaging for abdominal MRI applications. CONCLUSION Subtraction imaging has multiple applications for imaging the mediastinum, abdomen, and pelvis. Removing any preexisting signal of T1 unenhanced images causes contrast enhancement within a mass to become more conspicuous on subtracted sequences. This is helpful when evaluating a lesion with high signal on unenhanced T1-weighted sequences, where visual detection of enhancement can be difficult on conventional MRI.

Added Value of Diffusion-Weighted Acquisitions in MRI of the Abdomen and Pelvis

OBJECTIVE The purpose of this article is to review abdominopelvic applications of diffusion-weighted imaging (DWI), discuss advantages and limitations of DWI, and illustrate these with examples. CONCLUSION High-quality abdominopelvic DWI can be performed routinely on current MRI systems and may offer added value in image interpretation. Particularly in unenhanced MRI examinations, DWI may provide an alternative source of image contrast and improved conspicuity to identify and potentially characterize pathology. DWI is a powerful technique that warrants implementation in routine abdominal and pelvic imaging protocols.

MR imaging of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a common malignancy typically associated with chronic liver disease and is a leading cause of mortality among these patients. Prognosis is improved when detected early. MRI is the best imaging examination for accurate diagnosis. Although arterial enhancement with delayed washout, increased T2-weighted signal intensity, delayed capsular enhancement, restricted diffusion, and tumor thrombus are typical features, not all lesions demonstrate these findings. The radiologist must be familiar with these typical imaging characteristics, and less common appearances and associated findings of HCC, and must be able to differentiate them from those of lesions that mimic HCC. Knowledge of therapeutic options and how those are related to imaging findings is imperative to assist clinicians in managing these patients.

Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging to Identify Clear Cell Renal Cell Carcinoma in cT1a Renal Masses

Purpose: The detection of small renal masses is increasing with the use of cross‐sectional imaging, although many incidental lesions have negligible metastatic potential. Among malignant masses clear cell renal cell carcinoma is the most prevalent and aggressive subtype. A method to identify such histology would aid in risk stratification. Our goal was to evaluate a likelihood scale for multiparametric magnetic resonance imaging in the diagnosis of clear cell histology. Materials and Methods: We retrospectively reviewed the records of patients with cT1a masses who underwent magnetic resonance imaging and partial or radical nephrectomy from December 2011 to July 2015. Seven radiologists with different levels of experience who were blinded to final pathology findings independently reviewed studies based on a predefined algorithm. They applied a clear cell likelihood score, including 1—definitely not, 2—probably not, 3—equivocal, 4—probably and 5—definitely. Binary classification was used to determine the accuracy of clear cell vs all other histologies. Interobserver agreement was calculated with the weighted &kgr; statistic. Results: A total of 110 patients with 121 masses were identified. Mean tumor size was 2.4 cm and 50% of the lesions were clear cell. Defining clear cell as scores of 4 or greater demonstrated 78% sensitivity and 80% specificity while scores of 3 or greater showed 95% sensitivity and 58% specificity. Interobserver agreement was moderate to good with a mean &kgr; of 0.53. Conclusions: A clear cell likelihood score used with magnetic resonance imaging can reasonably identify clear cell histology in small renal masses and may decrease the number of diagnostic renal mass biopsies. Standardization of imaging protocols and reporting criteria is needed to improve interobserver reliability.

Complementary Roles of CT and Endoscopic Ultrasound in Evaluating a Pancreatic Mass

OBJECTIVE The objectives of our study were to illustrate normal pancreatic anatomy using endoscopic ultrasound and to show the imaging findings of solid pancreatic masses on endoscopic ultrasound and CT. CONCLUSION CT and endoscopic ultrasound have complementary roles in the diagnosis of solid pancreatic masses.

Postoperative Imaging after Surgical Repair for Pelvic Floor Dysfunction

Pelvic floor dysfunction encompasses an extremely common set of conditions, with various surgical and nonsurgical treatment options. Surgical options include injection of urethral bulking agents, native tissue repair with or without bioabsorbable or synthetic graft material, placement of synthetic midurethral slings or use of vaginal mesh kits, and mesh sacrocolpopexy procedures. Numerous different synthetic products with varied imaging appearances exist, and some of these products may be difficult to identify at imaging. Patients often present with recurrent or new symptoms after surgery; and depending on the presenting complaint and the nature of the initial intervention, imaging with ultrasonography (US), magnetic resonance (MR) imaging, voiding cystourethrography, or computed tomography (CT) may be indicated. US and MR imaging can both be used to image urethral bulking agents; US is often used to follow potential changes in bulking agent volume with time. Compared with MR imaging, US depicts midurethral slings better in the urethrovaginal space, and MR imaging is better than US for depiction of the arms in the retropubic space and obturator foramen. Mesh along the vaginal wall may be depicted with both US and MR imaging; however, the distal arms of the mesh traversing the sacrospinous ligaments or within the ischiorectal fossae (ischioanal fossae) are better depicted with MR imaging. Scarring can mimic slings and mesh at both US and MR imaging. MR imaging is superior to US for depiction of sacrocolpopexy mesh and associated complications. Voiding cystourethrography and CT are used less commonly because they rarely allow direct depiction of implanted material. Online supplemental material is available for this article. (©)RSNA, 2016.

Sarcoma botryoides: MRI findings in two patients.

We report the magentic resonance (MR) findings of sarcoma botryoides in two young pediatric patients with this tumor. There has been very little literature regarding the MR appearance of this subtype of rhabdomyosarcoma. In both cases, the tumor was vaginal in origin, as would be expected in this age group. We found areas of bright T2 signal within these lesions, intermixed with areas of lower T2‐signal tissue, which showed considerable enhancement. These imaging findings are reflective of the histologic architecture of these lesions, which are composed of separate myxoid and subepithelial cellular zones. In both cases, the extent of the tumor and lack of local invasion or metastatic disease were confirmed surgically, and both patients have undergone multiple postoperative MR studies that have shown lack of residual, recurrent, or metastatic disease. J. Magn. Reson. Imaging 2009;29:708–712.

Influence of rectal gel volume on defecation during dynamic pelvic floor magnetic resonance imaging

PURPOSE To evaluate effects of altering rectal contrast volume on defecatory effort during magnetic resonance defecography (MRD). METHODS We assessed defecation qualitatively and quantitatively as a function of rectal distention (group A: 180 cc, n=31; group B: 120 cc, n=31). Quantitative evaluation comprised measuring rectal area on midline sagittal images pre- and post-defecation. RESULTS Resting rectal area was significantly higher for group A than for group B (35.2 vs. 28.3 cm(2), P<.0001). Post-defecation rectal area and change in area (pre- to post-defecation) were not significantly different. Subjective evaluation showed no significant difference. CONCLUSION Decreasing rectal gel volume from 180 to 120 cc did not compromise defecation performance during MRD.