Peripheral Zone Enlargement: a newly described entity on MRI

Abstract

Purpose: A retrospective study was performed to describe and characterize a previously unreported finding on T2-weighted magnetic resonance imaging (MRI) of peripheral zone enlargement (PZE) associated with total prostatic enlargement without necessary association with benign prostatic hyperplasia (BPH) or lower urinary tract symptoms. Methods: T2-weighted MRI were reviewed from 2012-2018. Patients were referred for elevated serum prostatic specific antigen (PSA) levels, prostatic enlargement, or abnormal digital rectal examination (DRE) suggestive of adenocarcinoma. Enlargement of the thickness of the peripheral zone (PZ) was defined as a measurement of postero-lateral thickness (PLPZ) of ≥ 15.8 mm in the maximal transaxial plane. Endorectal coils were used in 2 patients. Microscopic pathology was described in 3 patients. Results: There were 22 patients who met the criteria out of 2871 subjects (<1%). Mean age was 63 years, Mean PLPZ was 17.7 mm (CI=0.45, range, 15.8-21.3). mean total prostatic volume was 55.1 cc (range, 19.9-127.2 cc), mean transition zone volume was 20.6 cc (range, 2.7-71.9 cc), mean transition zone index (TZI) was 0.34 (range, 0.31-0.68), mean prostatic specific antigen (PSA) was 13.9 ng/mL (range, 0.28-144.7), mean body mass index was 28.9 (range, 23.0-36.3).. Enlargement was described in 14 of 20 (70%). Pathological findings showed marked glandular distention and atrophy with interstitial edema and chronic inflammatory cells. Significance of these results is discussed.