MRI of Benign Prostatic Hyperplasia: Important Pre- and Posttherapeutic Considerations.

New minimally invasive techniques that reduce morbidity while improving lower urinary tract symptoms (LUTS) due to benign prostatic hypertrophy (BPH) have become attractive alternatives for patients, in comparison to traditional techniques such as transurethral resection of the prostate (TURP) and simple prostatectomy. Pre- and postprocedural MRI is not routinely performed for LUTS due to BPH treatments. However, because of the combination of rapidly evolving treatments available for LUTS due to BPH and increasing demand for prebiopsy prostate MRI for detection of clinically significant prostate cancer (PCa), an understanding of procedural techniques and expected changes are important for accurate interpretation of prostate MRI performed after treatment of BPH. The authors discuss the imaging evaluation of LUTS due to BPH and emerging predictors of treatment success. The posttreatment appearance and underlying anatomic changes in the prostate after medical, surgical, and minimally invasive treatments including TURP, simple prostatectomy, laser enucleations and ablations, prostatic urethral lift, water vapor thermal therapy, and prostate artery embolization are detailed. Most procedures reduce prostate volume, notably in the periurethral prostatic tissue. Ablations create areas of necrosis and can distort the normal zonal anatomy between the transition zone and the peripheral zone, and prostate artery embolization creates infarcts in the transition zone. Mechanical prostatic urethral lift devices open the anterior channel at the bladder base but create susceptibility artifacts that can obscure and prevent detection of a lesion in the transition zone. Also discussed are the detection of clinically significant prostate cancer in the postprocedural prostate and imaging of BPH procedure complications such as urethral strictures, abscesses, and hematuria. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material. See the invited commentary by Purysko in this issue.

Imaging of benign gallbladder and biliary pathologies in pregnancy.

The rising incidence combined with pregnancy-related physiological changes make gallbladder and biliary pathology high on the differential for pregnant patients presenting with right upper abdominal pain. Imaging plays a crucial role in determining surgical versus non-surgical management in pregnant patients with biliary or gallbladder pathology. Ultrasound (first-line) and magnetic resonance with magnetic resonance cholangiopancreatography (second-line) are the imaging techniques of choice in pregnant patients with suspected biliary pathology due to their lack of ionizing radiation. MRI/MRCP offers an excellent non-invasive imaging option, providing detailed anatomical detail without known harmful fetal side effects. This article reviews physiological changes in pregnancy that lead to gallstone and biliary pathology, key imaging findings on US and MRI/MRCP, and management pathways.

Imaging of benign biliary pathologies.

Pathologies of the biliary tree include a wide-spectrum of benign and malignant processes. The differential for benign disease includes congenital and acquired disease with variable prognosis and management pathways. Given the ability to mimic malignancy, benign processes are difficult to diagnose by imaging. Direct cholangiography techniques with tissue sampling are the gold standards for the diagnosis of benign and malignant biliary pathologies. Non-invasive imaging with ultrasound offers a first-line diagnostic tool while MRI/MRCP offers higher specificity for identifying underlying pathology and distinguishing from malignant disease. In this review, we focus on the imaging appearance of dilatation, cystic anomalies obstruction, inflammation, ischemia, strictures, pneumobilia, and hemobilia to help construct a differential for benign processes.

Primary biliary cholangitis: review for radiologists.

Primary biliary cholangitis is a rare progressive chronic inflammation of the medium and small bile ducts that abdominal radiologists may encounter, particularly if working in a tertiary setting or at a transplant center. This brief review covers current thinking about the pathophysiology and presentation of the disease, as well as the current diagnostic criteria in use by hepatologists. Imaging strategies for diagnosis will be reviewed as well as current treatment strategies and the use of imaging in monitoring response to treatment, including image-guided elastography.

Radiologic findings of biliary complications post liver transplantation.

Liver transplantation is a potentially curative treatment for patients with acute liver failure, end-stage liver disease, and primary hepatic malignancy. Despite tremendous advancements in surgical techniques and immunosuppressive management, there remains a high rate of post-transplant complications, with one of the main complications being biliary complications. In addition to anastomotic leak and stricture, numerous additional biliary complications are encountered, including ischemic cholangiopathy due to the sole arterial supply of the bile ducts, recurrence of primary biliary disease, infections, biliary obstruction from stones, cast, or hemobilia, and less commonly cystic duct remnant mucocele, vanishing duct syndrome, duct discrepancy and kinking, post-transplant lymphoproliferative disorder, retained stent, and ampullary dysfunction. This article presents an overview of biliary anatomy and surgical techniques in liver transplantation, followed by a detailed review of post-transplant biliary complications with their corresponding imaging findings on multiple modalities with emphasis on magnetic resonance imaging and MR cholangiopancreatography.

Primary sclerosing cholangitis: review for radiologists.

Primary sclerosing cholangitis is a rare chronic inflammatory disease affecting the bile ducts, which can eventually result in bile duct strictures, cholestasis and cirrhosis. Patients are often asymptomatic but may present with clinical features of cholestasis. Imaging plays an important role in the diagnosis and management. This review covers the pathophysiology, clinical features, imaging findings as well as methods of surveillance and post-transplant appearance.

Deep Learning in Kidney Ultrasound: Overview, Frontiers, and Challenges.

Ultrasonography is a practical imaging technique used in numerous health care settings. It is relatively inexpensive, portable, and safe, and it has dynamic capabilities that make it an invaluable tool for a wide variety of diagnostic and interventional studies. Recently, there has been a revolution in medical imaging using artificial intelligence (AI). A particularly potent form of AI is deep learning, in which the computer learns to recognize pixel or written data on its own without the selection of predetermined features, usually through a specific neural network architecture. Neural networks vary in architecture depending on their task, and key design considerations include the number of layers and complexity, data available, technical requirements, and domain knowledge. Deep learning models offer the potential for promising innovations to workflow, image quality, and vision tasks in sonography. However, there are key limitations and challenges in creating reliable and safe AI models for patients and clinicians.

What radiologists should know about microRNA (miRNA) serum biomarkers for germ cell tumors.

MicroRNAs expressed by germ cell tumors represent a novel approach to detection of metastatic disease during staging, surveillance, and recurrence post-therapy. It has particular promise in settings of equivocal imaging, such as clinical stage I GCT, tumor marker negative stage IIA, or after chemotherapy. These miRNAs have the potential to change typical serum marker evaluation and imaging surveillance schedules.

Dextran-Coated Cerium Oxide Nanoparticles: A Computed Tomography Contrast Agent for Imaging the Gastrointestinal Tract and Inflammatory Bowel Disease.

Computed tomography (CT) is an X-ray-based medical imaging technique commonly used for noninvasive gastrointestinal tract (GIT) imaging. Iodine- and barium-based CT contrast agents are used in the clinic for GIT imaging; however, inflammatory bowel disease (IBD) imaging is challenging since iodinated and barium-based CT agents are not specific for sites of inflammation. Cerium oxide nanoparticles (CeNP) can produce strong X-ray attenuation due to cerium's k-edge at 40.4 keV but have not yet been explored for CT imaging. In addition, we hypothesized that the use of dextran as a coating material on cerium oxide nanoparticles would encourage accumulation in IBD inflammation sites in a similar fashion to other inflammatory diseases. In this study, therefore, we sought to develop a CT contrast agent, i.e., dextran-coated cerium oxide nanoparticles (Dex-CeNP) for GIT imaging with IBD. We synthesized Dex-CeNP, characterized them using various analytical tools, and examined their in vitro biocompatibility, CT contrast generation, and protective effect against oxidative stress. In vivo CT imaging was done with both healthy mice and a dextran sodium sulfate induced colitis mouse model. Dex-CeNP's CT contrast generation and accumulation in inflammation sites were compared with iopamidol, an FDA approved CT contrast agent. Dex-CeNP was found to be protective against oxidative damage. Dex-CeNP produced strong CT contrast and accumulated in the colitis area of large intestines. In addition, >97% of oral doses were cleared from the body within 24 h. Therefore, Dex-CeNP can be used as a potential CT contrast agent for imaging GIT with IBD while protecting against oxidative damage.

The utility of retrograde pyelography to follow up incompletely opacified ureters on CT urography.

PURPOSE: Retrograde pyelography (RPG) is used in some centers to further evaluate patients with incompletely opacified segments on CT urography (CTU). This study intends to evaluate the utility of this imaging combination in terms of the yield of abnormal findings on the follow up RPG. METHODS: In this retrospective study, we searched the radiology database over a three-year period (11/1/2015-10/30/2018) for patients who had a CTU and then a diagnostic RPG within 180 days. Images and reports were reviewed from this period for patients who met the inclusion criteria. RESULTS: 292 patients underwent a CTU with follow up RPG over the search period. 131/292 RPGs (44.9%) were performed because the CTU described at least one incompletely opacified ureteral segment. Of the 148 ureters evaluated in these 131 patients, 4 ureters (2.7%) showed an abnormality on follow up retrograde pyelogram-two revealed a stricture at the unfilled segment, and two revealed contour irregularity in the distal ureter (biopsy showed urothelial cell carcinoma in these two). CONCLUSION: There is a relatively low yield for detecting ureteral abnormalities when a retrograde pyelogram is performed after a CTU to evaluate an incompletely opacified ureteral segment-2.7% in our study, with only two of these incompletely opacified segments containing urothelial cancer (1.4%). In these two cases, a ureteral abnormality was visible on the CTU and RPG would seem to have a very low yield for follow up of unopacified ureteral segments if the ureters are otherwise normal-appearing on CTU and there is no hydronephrosis.

The Sonographic Spectrum of Pelvic Endometriosis: Pearls, Pitfalls, and Mimics.

Endometriosis is a common disease of reproductive-age women that is often first encountered with ultrasound. Therefore, familiarity with the variety of manifestations of endometriosis is important for appropriate diagnosis and management. The aim of this article is to review the spectrum of appearance of pelvic endometriosis and to discuss potential mimics on ultrasound. Given that magnetic resonance imaging is an important problem-solving tool in female pelvic imaging, magnetic resonance imaging correlation is also provided.

Renal Imaging: Core Curriculum 2019.

Renal imaging has become a fundamental part of clinical care for patients with kidney disease. Imaging strategies for the kidney have been evolving during the past hundred years and have been even more rapidly changing during the past couple of decades due to the development of modern computed tomographic techniques, magnetic resonance imaging, and more sophisticated ultrasonographic techniques, such as contrast-enhanced ultrasonography. Applying the correct radiologic study for the clinical situation maximizes the diagnostic accuracy of the imaging, and a judicious choice between techniques helps limit radiation dose and potential adverse events. This Core Curriculum outlines the imaging modalities currently in use in radiology departments and is divided into 3 sections: (1) a review of the development of renal imaging and an outline of modalities available to the nephrologist, (2) imaging strategies for select clinical situations, and (3) a discussion of some potential adverse events from imaging, including effects of iodinated contrast on kidney function, risks of gadolinium-based contrast agents in kidney failure, and potential risks of imaging techniques that use ionizing radiation.

Ureteral pseudodiverticulosis and urothelial cell carcinoma: rethinking the association.

PURPOSE: To compare frequency of new and recurrent urothelial cell carcinoma (UCC) among patients with and without pseudodiverticulosis on imaging. METHODS: This retrospective case-control study compared all 113 sequential patients with ureteral pseudodiverticulosis on radiographic urography between 1/1/2002 and 12/31/2012. Six patients were lost to follow-up. 107 patients without pseudodiverticulosis were matched by imaging modality, clinical indication, and tumor grade. Known UCC and primary outcome of new or recurrent UCC were determined through pathology on cystoscopy or clinical follow-up. RESULTS: Nearly half of patients with pseudodiverticulosis had known UCC at the time of imaging (49/107, 46%). Mean cystoscopy follow-up was 7.0 and 4.6 years for pseudodiverticulosis cases with and without known UCC, respectively, and 7.5 and 7.3 years for controls, respectively. Mean clinic follow-up was 7.5 and 6.0 years for pseudodiverticulosis cases with and without known UCC, respectively, and 6.4 and 7.6 years for controls, respectively. Among patients with known UCC at the time of imaging, similar rates of recurrent UCC were demonstrated on follow-up among patients with pseudodiverticulosis (6/49, 12%) and without (7/49, 14%). Among patients with no known history of UCC at the time of imaging, no patients with pseudodiverticulosis developed UCC on follow-up and 5% (3/58) of patients without pseudodiverticulosis developed UCC. CONCLUSION: Although half of patients with ureteral pseudodiverticulosis have a known diagnosis of UCC, the presence of pseudodiverticulosis did not signify an increased likelihood of developing new or recurrent UCC over the follow-up period.

Voiding cystourethrography after prostatectomy: spectrum of appearances.

PURPOSE: This article reviews current prostatectomy techniques and then techniques for fluoroscopic voiding cystourethrography (VCUG) evaluation of the prostate and bladder after prostatectomy. Both normal post-prostatectomy appearances and complications will be reviewed. CONCLUSION: VCUG is a useful evaluation for both common and uncommon post-prostatectomy complications and appropriate interpretation of the VCUG complications is important to aid the urologist's clinical decision making.

Percutaneous cryoablation for recurrent low grade renal cell carcinoma after failed nephron-sparing surgery.

INTRODUCTION: Partial nephrectomy has a 3%-4% incidence of local treatment failure. This study is to present a series of percutaneous cryoablation for locally recurrent renal cell carcinoma after partial nephrectomy. MATERIALS AND METHODS: Five consecutive patients were referred to our quarternary center's multidisciplinary Small Renal Mass (SRM) Center for assessment after failure of partial nephrectomy. Tumor size and location was noted. CT-guided cryoablation was performed using an argon/helium-based system (Healthtronics, Austin, Texas, USA). Patients were admitted overnight for observation. Patients were followed with serial imaging, laboratory tests and examination at our SRM Center. Tumor size, location, and nephrometry scores were documented for each patient. RESULTS: Four tumors were endophytic and one was exophytic. The median tumor size was 2.2 cm (1.8 cm-4.0 cm). Nephrometry scores were 8a, 7x, 4p, 6x, 7p, and 6p prior to cryoablation. Median follow up after cryoablation was 32 months (20-39 months). One patient with a 4.0 cm endophytic tumor developed a second recurrence measuring 2.9 cm 13 months following ablation, which was managed successfully with repeat cryoablation with no evidence of disease after an additional 19 months of follow up. Two patients developed self-limited hematuria which was conservatively managed. There were no other complications, and all patients remained at their pretreatment performance status. CONCLUSIONS: Percutaneous cryoablation appears to be a safe and effective nephron-sparing modality for control of locally recurrent disease following partial nephrectomy. Most recurrent tumors are endophytic. One patient suffered a second local recurrence, which was managed successfully with repeat cryoablation.

The SAR analysis of TRPV1 agonists with the α-methylated B-region.

A series of TRPV1 agonists with amide, reverse amide, and thiourea groups in the B-region and their corresponding α-methylated analogues were investigated. Whereas the α-methylation of the amide B-region enhanced the binding affinities and potencies as agonists, that of the reverse amide and thiourea led to a reduction in receptor affinity. The analysis indicated that proper hydrogen bonding as well as steric effects in the B-region are critical for receptor binding.