Prostate MRI

What it does

Prostate MRI reads biparametric (T2W and diffusion) and multiparametric (with DCE) studies in the MRI-first diagnostic pathway. The run segments the gland and its peripheral and transition zones, measures the volume and, with a PSA value, the PSA density. It then detects suspicious lesions, segments each one, places it on the PI-RADS v2.1 sector map and assigns a PI-RADS category.

Around the lesion list, the result states whether each sequence is diagnostically adequate (PI-QUAL), flags extraprostatic extension and seminal vesicle invasion per side, and exports biopsy targets that fusion-biopsy systems import. With a prior study on active surveillance, lesions are matched and scored with PRECISE; after prostatectomy or radiotherapy, the read follows PI-RR for local recurrence.

Intended use

Decision support for physicians reporting prostate MRI, where transition-zone lesions and PI-RADS 3 versus 4 calls vary most between readers: a consistent lesion list with measurements and sector locations, and a quality statement that says when image quality limits a negative read.

Who it is for

Radiologists who report prostate MRI at any volume, urologists planning targeted biopsy or active surveillance, and radiation oncologists. Through the API, targets and contours flow to fusion-biopsy platforms and urology registries.

Accepted input

• DICOM MR study (MR Image, Enhanced MR or Legacy Converted Enhanced MR) as a zip or by DICOMweb STOW-RS; NIfTI with a BIDS-style sidecar (b-values included) on the API.
• Prior prostate MRI in prior_files for PRECISE assessment on active surveillance.
• Sequences are classified automatically, including vendor-computed versus synthetic high-b images.

Requirements

Requirement	Why
Axial T2W	Reference series for zones, lesion shape and transition-zone scoring
DWI with a high b-value (≥1400 s/mm²)	Dominant sequence for the peripheral zone; computed from the acquired b-values when absent
ADC map	Scores diffusion restriction with the high-b images; computed from DWI when not supplied
DCE (optional)	A positive DCE upgrades a peripheral-zone DWI score of 3 to PI-RADS 4; also supports local staging and recurrence reads

Missing or degraded DWI (rectal gas, hip prostheses) and post-biopsy haemorrhage are reported in the quality section rather than silently scored.

Optional context

PSA (for PSA density), prior biopsy results, treatment history (prostatectomy, radiotherapy) and active-surveillance status go in clinical_context.

The result

Section	Content
Image quality (PI-QUAL)	Per-sequence diagnostic adequacy, artefacts (gas, motion, distortion) and the PI-QUAL score
Gland and zones	Whole-gland, peripheral-zone and transition-zone masks, gland volume, PSA density when PSA is given
PI-RADS lesions	Each lesion with mask, size, zone, sector-map location, PI-RADS v2.1 category and a biopsy target
Local staging	Likelihood of extraprostatic extension, seminal vesicle and neurovascular-bundle invasion per side
Active surveillance (PRECISE)	Lesion matching against the prior, size change and PRECISE score
Recurrence (PI-RR)	Local recurrence likelihood and location after prostatectomy or radiotherapy
Draft report	Opt-in (options.report): an English narrative that interprets the result for the reader (findings, impression, limitations); every number is checked against the findings

Standards

• DICOM: SEG for zones and lesions; RTSTRUCT for biopsy targets on request; SR TID 1500 with one group per lesion and tracking identifiers that persist across visits; ADC as a Parametric Map; KOS key images and Encapsulated PDF.
• Reporting: PI-RADS v2.1 categories and its sector map (returned as a sector_map block), with the PI-RADS v2.1 features for extraprostatic extension.
• Quality: PI-QUAL v2 (2024).
• Follow-up: PRECISE v2 (2024) for active surveillance and PI-RR for recurrence.

Scoring notes

Gland volume comes from the segmentation in millilitres, so PSA density is PSA divided by that volume. The PI-RADS category follows the dominant sequence of each zone: diffusion in the peripheral zone, T2W in the transition zone.