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 Features at the Periphery: Hemodynamics, Pathophysiology, and Effect on LI-RADS Categorization.

Liver lesions have different enhancement patterns at dynamic contrast-enhanced imaging. The Liver Imaging Reporting and Data System (LI-RADS) applies the enhancement kinetic of liver observations in its algorithms for imaging-based diagnosis of hepatocellular carcinoma (HCC) in at-risk populations. Therefore, careful analysis of the spatial and temporal features of these enhancement patterns is necessary to increase the accuracy of liver mass characterization. The authors focus on enhancement patterns that are found at or around the margins of liver observations-many of which are recognized and defined by LI-RADS, such as targetoid appearance, rim arterial phase hyperenhancement, peripheral washout, peripheral discontinuous nodular enhancement, enhancing capsule appearance, nonenhancing capsule appearance, corona enhancement, and periobservational arterioportal shunts-as well as peripheral and periobservational enhancement in the setting of posttreatment changes. Many of these are considered major or ancillary features of HCC, ancillary features of malignancy in general, features of non-HCC malignancy, features associated with benign entities, or features related to treatment response. Distinction between these different patterns of enhancement can help with achieving a more specific diagnosis of HCC and better assessment of response to local-regional therapy. ©RSNA, 2021.

MR Imaging-Guided Transurethral Ultrasound Ablation of Localized Prostate Cancer: Preliminary Experience from a Single Center in a Prospective, Multi-Center, Single-Arm Clinical Trial.

This report details a single-center experience of using magnetic resonance imaging-guided transurethral ultrasound ablation (TULSA) for whole-gland prostate treatment. Nine men with organ-confined low-to-intermediate-risk prostate cancer underwent the TULSA procedure. The primary endpoint of reduction of more than 75% was achieved in 8 of 9 patients, and all patients demonstrated a histologic benefit at 12-month biopsy. No major urinary or gastrointestinal side effects were observed, and there were no postprocedural changes in erectile firmness. These findings suggest that TULSA is potentially safe and efficacious for patients with low-to-intermediate-risk disease.

MRI of the Male Pelvic Floor.

The pelvic floor is a complex structure that supports the pelvic organs and provides resting tone and voluntary control of the urethral and anal sphincters. Dysfunction of or injury to the pelvic floor can lead to gastrointestinal, urinary, and sexual dysfunction. The prevalence of pelvic floor disorders is much lower in men than in women, and because of this, the majority of the published literature pertaining to MRI of the pelvic floor is oriented toward evaluation of the female pelvic floor. The male pelvic floor has sex-specific differences in anatomy and pathophysiologic disorders. Despite these differences, static and dynamic MRI features of these disorders, specifically gastrointestinal disorders, are similar in both sexes. MRI and MR defecography can be used to evaluate anorectal disorders related to the pelvic floor. MRI can also be used after prostatectomy to help predict the risk of postsurgical incontinence, to evaluate postsurgical function by using dynamic voiding MR cystourethrography, and subsequently, to assess causes of incontinence treatment failure. Increased tone of the pelvic musculature in men secondary to chronic pain can lead to sexual dysfunction. This article reviews normal male pelvic floor anatomy and how it differs from the female pelvis; MRI techniques for imaging the male pelvis; and urinary, gastrointestinal, and sexual conditions related to abnormalities of pelvic floor structures in men.Online supplemental material is available for this article.©RSNA, 2019.

Multisite, multivendor validation of the accuracy and reproducibility of proton-density fat-fraction quantification at 1.5T and 3T using a fat-water phantom.

PURPOSE: To evaluate the accuracy and reproducibility of quantitative chemical shift-encoded (CSE) MRI to quantify proton-density fat-fraction (PDFF) in a fat-water phantom across sites, vendors, field strengths, and protocols. METHODS: Six sites (Philips, Siemens, and GE Healthcare) participated in this study. A phantom containing multiple vials with various oil/water suspensions (PDFF:0%-100%) was built, shipped to each site, and scanned at 1.5T and 3T using two CSE protocols per field strength. Confounder-corrected PDFF maps were reconstructed using a common algorithm. To assess accuracy, PDFF bias and linear regression with the known PDFF were calculated. To assess reproducibility, measurements were compared across sites, vendors, field strengths, and protocols using analysis of covariance (ANCOVA), Bland-Altman analysis, and the intraclass correlation coefficient (ICC). RESULTS: PDFF measurements revealed an overall absolute bias (across sites, field strengths, and protocols) of 0.22% (95% confidence interval, 0.07%-0.38%) and R2 > 0.995 relative to the known PDFF at each site, field strength, and protocol, with a slope between 0.96 and 1.02 and an intercept between -0.56% and 1.13%. ANCOVA did not reveal effects of field strength (P = 0.36) or protocol (P = 0.19). There was a significant effect of vendor (F = 25.13, P = 1.07 × 10-10 ) with a bias of -0.37% (Philips) and -1.22% (Siemens) relative to GE Healthcare. The overall ICC was 0.999. CONCLUSION: CSE-based fat quantification is accurate and reproducible across sites, vendors, field strengths, and protocols. Magn Reson Med 77:1516-1524, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Magnetic resonance-ultrasound fusion prostate biopsy in the diagnosis of prostate cancer.

The advent of multiparametric magnetic resonance imaging (MRI) has ushered in a new era for urologists who perform prostate needle biopsies. The fusion of MRI with transrectal ultrasound (US) allows the direct targeting of suspicious lesions, which has been shown to improve the performance of conventional random biopsy techniques by increasing detection of clinically relevant disease while also decreasing detection of low-risk cancer. However, as with any new technology, many questions regarding effectiveness, reproducibility, and generalizability still remain. In this review, we (1) provide a summary of the various sequences that comprise a MRI of the prostate; (2) evaluate the 3 different ways of incorporating MRI into targeted biopsies of the prostate including in-bore MRI-guided biopsy, cognitive fusion, and device-mediated fusion; (3) review the sensitivity of MR-US fusion in the detection of clinically significant and clinically insignificant disease; and (4) review the barriers to the widespread implementation of MR-US fusion into everyday practice. Whereas other articles in this issue of Urologic Oncology Seminars will discuss other aspects of MRI in the management of prostate cancer, the purpose of this article is to provide an overview of MR-US fusion biopsies in the diagnosis of prostate cancer.

Difficult biopsy and drainage: just say yes.

Abdominal radiologists are often asked to perform difficult percutaneous chest, abdomen, and pelvis biopsies and drainages with imaging guidance. Many of these procedures involve small target lesions far from the skin surface, in close proximity to critical structures. Organ location is changeable due to respiration, peristalsis, and pulsation, further complicating the planning process. High-level three-dimensional spatial awareness is critical to mastery of complex image-guided procedures. A comprehensive grasp of anatomy and expected changes can be exploited in certain cases to target lesions within a solid organ or to avoid injury to sensitive structures during biopsy, drain placement, or thermal ablation. In this article, we will use illustrative cases to explore the use of anatomic knowledge and the ability to synthesize this three-dimensional data dynamically during planning and execution of difficult CT- and ultrasound-guided procedures. We will discuss unusual biopsy requests-such as bowel biopsies-and the benefits of using ultrasound guidance for certain procedures in the chest. Additionally, we will describe multiple special techniques, including out of standard plane angulation and endocavitary techniques, in order to maximize chances of success.

CT and MRI of congenital anomalies of the seminal vesicles.

OBJECTIVE: The purpose of this article is to provide a current review of the spectrum of CT and MRI findings seen in common congenital anomalies of the seminal vesicles. CONCLUSION: CT and MRI can both accurately show renal and seminal vesicle anomalies. Seminal vesicle anomalies often occur concurrently with renal and vasal defects. MRI is a better tool for accurately defining anatomic relationships when one is planning to excise a seminal vesicle cyst or if one is considering a difficult differential diagnosis.