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OBJECTIVE. The purpose of this article is to evaluate the MR findings of prostatic remnant after prostatectomy and estimate the prevalence of prostatic remnant in patients that undergo MRI after prostatectomy. MATERIALS AND METHODS. Sixty-six patients who had undergone radical prostatectomy with pathologically proven benign prostatic remnant between 2007 and 2017 were retrospectively reviewed. Pathologically proven benign prostatic remnant was determined on the basis of initial pathologic report. Of the 66 initial patients, 30 patients with biopsy-proven benign prostatic remnant without coexisting recurrent prostate carcinoma and three patients who underwent repeat resection for completion prostatectomy were enrolled. MRI characteristics including location, size, signal intensity on T2-weighted images and DWI, and contrast enhancement pattern were analyzed. Nine additional patients were found to have a prostatic remnant by imaging without biopsy. The prevalence of prostatic remnant among those undergoing MRI for suspected recurrence during the same period was estimated. RESULTS. Prostatic remnant was detected in 23 of 33 patients on MRI. The remaining 10 patients did not have any visible abnormality. The 23 detected lesions were located in three regions: under the vesicourethral anastomosis in five patients, in the bladder neck in 12 patients, and posterior to the bladder in six patients. On T2-weighted imaging, 17 of 23 lesions showed heterogeneous hyperintensity. On DWI, 14 lesions showed hyperintensity. Dedicated MRI studies were performed for suspected prostate cancer recurrence in 2466 patients during the same period. Prevalence of exclusively benign prostate remnant detectable on MRI was approximately 1% of that population (23/2466-35/2466), and overall prevalence of any prostate remnant detectable on MRI was 3% (75/2466). CONCLUSION. Benign prostate remnant after prostatectomy occurs at three common sites and typically shows heterogeneous hyperintensity on T2-weighted imaging. The prevalence of detectable prostatic remnant in men who undergo MRI for suspected recurrence was approximately 1-3%.

The purpose of this study is to report the patient safety and image quality of 1.5-T multiparametric MRI of the prostate in patients with cardiac implantable electronic devices (CIEDs).In this retrospective study, a database was searched to identify prostate multiparametric 1.5-T MRI examinations performed with endorectal coils for patients with CIEDs from 2012 to 2016 (study group) and matched patients without CIEDs (control group). Clinical safety in the study group was reviewed. The specific absorption rate (SAR) and signal-to-noise ratio (SNR) were measured in both groups. Imaging quality and artifact on T2-weighted images, DW images, and dynamic contrast-enhanced images were rated on a 5-point scale by two independent readers.The study group consisted of total 28 multiparametric MRI examinations in 25 patients. There were no serious device-related adverse effects observed (0/28; 0%), and the estimated whole-body SAR in the study group was never greater than 1.5 W/kg. The SNR values tended to be lower in the study group than in the control group. However, overall perceived image preferences and influences of artifacts on image quality for the study group were not significantly different from those for the control group (p0.05), which were rated above average (rating 3) by both readers 1 and 2.Multiparametric 1.5-T MRI examination of the prostate can be safely performed in selected patients with CIEDs under controlled conditions with applicable image quality while maintaining a SAR less than 1.5 W/kg.

The objective of our study was to compare a flavored beverage containing a thickening agent for enterography with a low-Hounsfield-value barium suspension for side effects, taste, subjects' willingness to repeat the drinking protocol, and small-bowel distention.The following five drinking protocols were administered to 10 volunteers: 1000 mL of flavored beverage followed by 350 mL of water, 1500 mL of flavored beverage, 900 mL of low-Hounsfield-value barium suspension followed by 450 mL of water, 1350 mL of low-Hounsfield-value barium suspension followed by 150 mL of water, and 1500 mL of water. MR images were obtained 50 and 60 minutes after initiation of drinking. Subjects completed a questionnaire evaluating the side effects, the taste of the drink, and their willingness to repeat the drinking protocol. Reviewers assigned scores evaluating small-bowel distention and ranked the examinations in order of preference.There was no significant difference in nausea or vomiting among the protocols (p = 0.20 and 0.42, respectively), but larger volumes of flavored beverage and low-Hounsfield-value barium suspension resulted in more cramping and diarrhea (p = 0.001 and 0.002, respectively). The taste of the low-Hounsfield-value barium suspension was rated the worst (p0.0001). The subjects' willingness to repeat the drinking protocol was highest for the 1000 mL of flavored beverage or water alone (p0.05). There were no significant differences in subjective small-bowel distention except that water was rated the worst by two of the three readers (p0.02). There was no significant difference in the diameter of the most dis-tended small bowel for any segment or reader (p0.23).A flavored beverage containing a thickening agent has a similar side effect profile and results in equivalent small-bowel distention compared with a low-Hounsfield-value barium suspension, but subjects rate taste and their willingness to repeat the drinking protocol higher for this new agent.

The purpose of this study was to assess the utility of DWI and dynamic contrast enhancement (DCE) in MRI at 3 T with an endorectal coil in identifying local prostate cancer recurrence after radical prostatectomy.Eighty men underwent MRI for suspected local recurrence. The reference standards were histopathologic result, decrease in prostate-specific antigen level after salvage radiation therapy, and follow-up findings. Using a 5-point scoring system, two reviewers independently interpreted T2-weighted images alone (protocol A), a combination of T2-weighted and DW images (protocol B), a combination of T2-weighted and DCE images (protocol C), and a combination of T2-weighted, DW, and DCE images (protocol D). ROC analysis was used to compare the four protocols.Local recurrence was found in 57 of the 80 patients (71.3%). The ROC AUCs for protocols A, B, C, and D were 0.71, 0.72, 0.90, and 0.89 for reader 1 and 0.65, 0.62, 0.84, and 0.83 for reader 2. Protocols C and D had statistically better performance than protocols A and B for both readers (p0.001). For local recurrence lesions with a long-axis diameter less than 10 mm visualized with protocol C, protocol B had detection rates of 25.0-29.4% and for lesions measuring 10 mm or greater, 67.9-69.0%. The rates of detection of local recurrence with protocol C or D were 76.5-82.4% for prostate-specific antigen levels less than 0.4 ng/mL, 60-73.3% for 0.4-1.0 ng/mL, and 80-88.0% for greater than 1.0 ng/mL.Addition of DCE to T2-weighted imaging in 3-T MRI with an endorectal coil improves the accuracy of detection of local cancer recurrence after radical prostatectomy. The addition of DWI is of limited incremental value for detection, especially of small lesions.

The purpose of this study was to describe the imaging features of renal epithelioid angiomyolipoma (EAML), a rare subtype of angiomyolipoma, with clinical and pathologic correlation.This study was a retrospective review of nine cases from a single institution in which total resection and preoperative imaging were performed and the diagnosis of EAML was made. Imaging included CT (nine cases), MRI (five cases), and ultrasound (one case), and the images were reviewed in consensus by two radiologists. Patient demographics, disease associations, presentation, and outcomes were determined by chart review.The patients were nine women and one man (mean age, 42 years). Two patients had tuberous sclerosis complex. The size of the nine EAMLs ranged from 1.4 to 22 cm (mean, 7.8 cm). Six lesions had minor components of fat identifiable at imaging. The contrast enhancement pattern was heterogeneous in eight lesions, five of which contained cysts, necrosis, and hematoma. Four presentations were acute hemorrhage, with ruptured EAML in three of the four. Five tumors extended into the renal sinus. Two tumors were locally invasive. One patient had metastatic disease at presentation with epithelioid tumor identified in a single lymph node. The follow-up periods ranged from 0 to 89 months, and there was one case of suspected but not yet proved recurrence.Renal EAML can have a range of imaging appearances and can be indistinguishable from renal cell carcinoma and angiomyolipoma with minimal fat. EAML can be considered when a mass is found that has small foci of macroscopic fat without calcification or when acute hemorrhage of a renal mass occurs.