Fig. 1

Multi-parametric magnetic resonance (MR) imaging of the prostate gland demonstrates normal prostate gland however an abnormal lesion in the left seminal vesicle features classical imaging features of prostate carcinoma. a High-resolution axial T2-weighted (T2W) image demonstrates an abnormal 1.5 × 1.2 × 1.0 cm lesion with relative hypointensity (arrow) subjacent to an enlarged prostate gland (arrowhead). The capsule is maintained without trans-capsular extension. b–c High-resolution multi-planar T2W images in the sagittal and coronal planes show, to advantage, this lesion within the left seminal vesicle (arrow), external to the capsule of the prostate gland (arrowhead). No T2W signal intensity abnormality is in the adjacent left prostate gland base peripheral or transitional zone. Moreover, there is no exophytic hyperplastic nodule or contiguous extension of prostatic glandular tissue related to the abnormality in the left seminal vesicle. Normal right seminal vesicle denoted for comparison (asterisk). d High b-value diffusion weighted imaging (DWI) shows that this lesion demonstrates significantly diminished diffusivity (arrow). e Apparent diffusion coefficient (ADC) map confirms significantly diminished diffusivity in this lesion (arrow) with low ADC mean value of 0.5 × 10⁻³ mm²/s (region of interest). No diminished diffusivity was seen in the prostate gland (arrowhead)