Guideline for Multiparametric MRI of the Prostate and Bladder

Imaging Protocol Recommendations

The American College of Radiology recommends ordering a multiparametric MRI of the pelvis (with and without intravenous contrast) on a 1.5 T or 3 T scanner—preferably 3 T—using a pelvic phased‑array surface coil and including T2‑weighted, diffusion‑weighted, and dynamic contrast‑enhanced sequences for simultaneous prostate and bladder evaluation. 1

A 3 T system provides image quality comparable to a 1.5 T system equipped with an endorectal coil when multichannel phased‑array coils are used. 4

T2‑weighted imaging (axial, sagittal, coronal) delivers detailed anatomy of the prostate zones, seminal vesicles, ejaculatory ducts, and bladder wall layers. 4
T2‑weighted imaging is essential for assessing the depth of bladder wall invasion and for differentiating superficial from deep muscle invasion. 1
Compared with CT, T2‑weighted MRI is superior for detecting detrusor muscle invasion and perivesical tissue involvement. 2
Diffusion‑weighted imaging (DWI) with ADC maps markedly improves the ability to distinguish muscle‑invasive from non‑muscle‑invasive bladder cancer, achieving a sensitivity of 78–98 % and specificity of 82–100 %. 1
DWI also enhances detection of malignant pelvic lymph nodes, with reported sensitivity of 61–94 % and specificity of 90–99 %. 6
Dynamic contrast‑enhanced (DCE) imaging is mandatory; intravenous gadolinium administration significantly raises staging accuracy. 1
With contrast, sensitivity for differentiating organ‑confined from non‑organ‑confined bladder cancer rises to 88 % and overall accuracy to 74 %. 1
DCE provides a sensitivity of 41 % and specificity of 92 % for identifying nodal disease. 1

Combining T2‑weighted, DWI, and DCE sequences constitutes the optimal technique for local staging of both bladder and prostate pathology. 1
This multiparametric strategy yields a sensitivity of 90–94 % and a specificity of 60–94 % for distinguishing organ‑confined from non‑organ‑confined bladder tumors. 1

For bladder cancer, the American College of Radiology endorses the VI‑RADS (Vesical Imaging‑Reporting and Data System) 5‑point scoring system to estimate the likelihood of detrusor muscle invasion. 2

Small field‑of‑view: High‑resolution axial T1‑weighted and multiplanar T2‑weighted sequences are recommended for detailed evaluation of the prostate gland, seminal vesicles, ejaculatory ducts, and bladder wall. 4
Large field‑of‑view: Extended coverage should be used to assess pelvic lymphadenopathy and extravesical disease spread. 4

MRI examinations for bladder staging must include contrast; non‑contrast protocols provide insufficient accuracy and should be avoided. 6

When upper‑tract assessment is required, MR urography (with and without contrast) can be added, offering superior contrast resolution compared with CT urography for detecting small tumors. 6
PSMA PET/CT may be considered as an adjunct in high‑risk disease or biochemical recurrence, although current data support only limited routine use. 8