What You Need to Know Before Reading Multiparametric MRI for Prostate Cancer

Radiologic-pathologic correlation of prostatic cancer extracapsular extension (ECE)

Recent advancements on nerve-sparing robotic prostatectomy allow fewer side effects such as urinary incontinence and sexual dysfunction. To perform such techniques, it is essential for the surgeon to know if the neurovascular bundle is involved. Despite being the gold-standard imaging method for Prostate Cancer (PCa) staging, Magnetic Resonance Imaging (MRI) lacks high specificity for detecting extracapsular extension (ECE). Therefore, it is essential to understand the pathologic aspects of ECE to better evaluate the MRI findings of PCa. We reviewed the normal MRI appearance of the prostate gland and the periprostatic space and correlated them to prostatectomy specimens. The different findings of ECE and neurovascular bundle invasion are exemplified with images of both MRI and histologic specimens.

MR fingerprinting of the prostate

Multiparametric magnetic resonance imaging (mpMRI) has been adopted as the key tool for detection, localization, characterization, and risk stratification of patients suspected to have prostate cancer. Despite advantages over systematic biopsy, the interpretation of prostate mpMRI has limitations including a steep learning curve, leading to considerable interobserver variation. There is growing interest in clinical translation of quantitative imaging techniques for more objective lesion assessment. However, traditional mapping techniques are slow, precluding their use in the clinic. Magnetic resonance fingerprinting (MRF) is an efficient approach for quantitative maps of multiple tissue properties simultaneously. The T₁ and T₂ values obtained with MRF have been validated with phantom studies as well as in normal volunteers and patients. Studies have shown that MRF-derived T₁ and T₂ along with ADC values are all significant independent predictors in the differentiation between normal prostate tissue and prostate cancer, and hold promise in differentiating low and intermediate/high-grade cancers. This review seeks to introduce the basics of the prostate MRF technique, discuss the potential applications of prostate MRF for the characterization of prostate cancer, and describes ongoing areas of research.

Impact of enema prep on the false-negative rate of a PI-RADS 1 MRI of the prostate for clinically significant prostate cancer

PURPOSE

To investigate whether use of an enema prep reduces the false-negative (FN) rate of PI-RADS 1 MRI of the prostate for clinically significant prostate cancer (csPCa).

MATERIALS AND METHODS

1108 consecutive patients with a PI-RADS 1 MRI performed 01/2016-09/2021 were retrospectively collected. Patient charts were examined for subsequent systematic prostate biopsy performed within 1 year if positive or anytime thereafter if negative. Patients without biopsy were excluded. Use of an enema prep 1-2 h before MRI, which was implemented in 03/2019, was recorded. FN rate of MRI for detection of csPCa, defined as Gleason score ≥ 7, using systematic biopsy was assessed per patient and compared between those with and without an enema prep. Χ² test and logistic regression were performed.

RESULTS

255 patients (median age 64, IQR 58-69) with median PSA 5.6 (IQR 4.2-8.1), PI-RADS 1 MRI, and subsequent biopsy were included in the analysis. 66 patients (26%) had an enema prep and 189 patients (74%) did not. 7 (11%) patients with and 21 (11%) patients without enema prep had a FN biopsy. There was no significant association between enema prep and FN biopsy (OR 0.95, 95% CI 0.38-2.35, p = 0.91).

CONCLUSIONS

Use of an enema prep prior to prostate MRI did not decrease the FN rate of PI-RADS 1 MRI of the prostate for clinically significant prostate cancer.