Computed Diffusion-Weighted Imaging in Prostate Cancer: Basics, Advantages, Cautions, and Future Prospects

Computed diffusion-weighted MRI is a recently proposed post-processing technique that produces b-value images from diffusion-weighted imaging (DWI), acquired using at least two different b-values. This article presents an argument for computed DWI for prostate cancer by viewing four aspects of DWI: fundamentals, image quality and diagnostic performance, computing procedures, and future uses.

Yield of Repeat Targeted Direct in-Bore Magnetic Resonance-Guided Prostate Biopsy (MRGB) of the Same Lesions in Men Having a Prior Negative Targeted MRGB

OBJECTIVE: This study's purposes were to determine the yield of repeat direct in-bore magnetic resonance-guided prostate biopsy (MRGB) (MRGB-2) after the first one was found to be negative (MRGB-1), to correlate with clinical parameters, and to present the subgroup analyses of patients with positive repeat biopsies, despite having a negative initial biopsies. MATERIALS AND METHODS: We retrospectively included patients with MRGB-2 after a negative MRGB-1 both between January 2006 and August 2016. This study included 62 patients (median age, 63 years; interquartile range [IQR], 58–66 years) with 75 sampled lesions during MRGB-2 left for analysis, and 63 lesions were resampled and 12 new lesions were sampled. Included patients had a prostate specific antigen (PSA) at MRGB-1 of 13 ng/mL (IQR, 5.8–20.0) and a PSA at MRGB-2 of 15 ng/mL (IQR, 9.0–22.5). All anonymized magnetic resonance imaging (MRI) data were retrospectively reassessed according to Prostate Imaging-Reporting and Data System version 2 by two radiologists. Images of MRGB were compared to determine whether the same prostate lesion was biopsied during MRGB-1 and MRGB-2. Descriptive statistics were utilized to determine the yield of clinically significant prostate cancer (csPCa) at MRGB-2. Gleason score of ≥ 3 + 4 was considered csPCa. RESULTS: In 16/75 (21%) lesions csPCa was detected during MRGB-2. Of 63 resampled lesions, 13 (21%) harbored csPCa at MRGB-2. In two patients, csPCa was detected on repeat biopsy, while the volume of the lesion decreased between MRGB-1 and MRGB-2. CONCLUSION: Patients could benefit from repeat biopsy after negative initial MRGB, especially in the case of increasing PSA values and persisting PCa suspicion in MRI. Further research is needed to establish predictors for positive repeat targeted biopsies.

MRI Appearance of Prostatic Stromal Sarcoma in a Young Adult

Prostatic stromal sarcoma (PSS) is quite rare. Herein, we describe magnetic resonance imaging (MRI) features of a PSS identified in a 26-year-old man with dysuria and hematuria. MRI clearly depicted the extent and multinodular appearance of the tumor, which was mainly located in the central zone of the prostate. The tumor appeared as a heterogeneously signal-hyperintense mass with a pseudocapsule on T2-weighted imaging. Contrast-enhanced T1-weighted MRI showed necrotic portions in the gradually enhanced solid mass, and diffusion-weighted imaging permitted the accurate assessment of the local extent of the tumor. Thus, the appearance on MRI was quite different from that of adenocarcinoma of the prostate.