The purpose of this study was to evaluate precise location criteria on magnetic resonance imaging (MRI) to improve detection of transition zone (TZ) and anterior stroma (AS) prostate cancers using targeted MRI/transrectal ultrasound fusion biopsies as a reference standard.

Ninety-six men (mean age: 65 years±7.7 [SD] [range: 46–83 years]) with an elevated prostate-specific antigen (PSA) (PSA≥4ng/mL) who underwent standard and targeted biopsies on a TZ/AS suspicious lesion were included. The database was reviewed to assess topographical and morphological features of each suspicious lesion on MR images (T2-weighted anatomical images on 1.5T MRI or 3T) including PI-RADS score assessed by a senior radiologist. Histopathological examination of MRI-transrectal ultrasound fusion biopsy specimens was used as the reference standard.

Ninety patients had a positive targeted biopsy with a median [IQR] lesion size of 16mm [13–20mm]. Homogeneous hypointensity on T2-weighted mages, lenticular shape, lack of capsule and indistinct margins were present in 77/90 (85%) patients. All TZ/AS prostate cancers were located in the anterior half of the prostate: 3% at the base, 69% in the mid gland and 28% at the apex. Lesions were mainly located close to or within the AS (74%) and more rarely laterally compressed close to the peripheral anterior horn.

Our results suggest that specific topographic criteria of TZ and AS prostate cancers could add independent information to the usual diagnostic criteria in prostate MRI. Transrectal ultrasound fusion-targeted biopsies based on these specific criteria improve volume estimation of prostate cancers with substantial impact for prognosis and treatment planning.