Pelvic MRI

What it does

Pelvic MRI reads the non-prostate pelvic protocols: rectal cancer staging and restaging, cervical and endometrial cancer, adnexal masses that are indeterminate on ultrasound, fibroids and adenomyosis, endometriosis and perianal fistula. Each indication has its own structured checklist, so the run first recognises the protocol (for example an oblique high-resolution T2 angled to the rectal tumour) and then returns the section that matches it.

For rectal cancer it reports the full staging checklist: tumour height, T stage, distance to the mesorectal fascia, extramural venous invasion, nodes and, after neoadjuvant therapy, the MR tumour regression grade. Fascia involvement and venous invasion are the items generalists most often miss. For gynaecological cancers it returns the FIGO stage with the invasion features behind it; for adnexal masses, the O-RADS MRI score; for benign disease, a fibroid map with FIGO types, an endometriosis map and a fistula classification.

Intended use

Decision support for physicians reporting pelvic MRI against checklists that are long and indication-specific: a complete structured read for the multidisciplinary meeting, with each stage-defining feature stated and located. Every staging item comes with its image evidence.

Who it is for

Abdominal, pelvic and general radiologists; colorectal surgeons and oncologists in rectal cancer pathways; gynaecological oncologists; gynaecologists treating fibroids, adenomyosis and endometriosis; and gastroenterologists and surgeons managing perianal Crohn's disease.

Accepted input

• DICOM pelvic MR study (MR Image, Enhanced MR or Legacy Converted Enhanced MR), zipped or sent by DICOMweb STOW-RS; NIfTI with a BIDS-style sidecar on the API.
• Prior study in prior_files for rectal restaging after neoadjuvant treatment.
• Plane, obliquity, fat suppression and contrast phase of every series are recognised from acquisition tags.

Sequences per indication

Section	Needs
Rectal cancer staging	High-resolution oblique axial T2, ± DWI
Cervical cancer staging	T2 and DWI
Endometrial cancer staging	T2, DWI and DCE
Adnexal mass (O-RADS MRI)	T2, DWI and DCE
Fibroids and adenomyosis	Sagittal and axial T2, ± post-contrast
Endometriosis	T2 and fat-suppressed T1
Perianal fistula	Fat-suppressed T2 and post-contrast T1

Optional context

The indication, treatment status (before or after chemoradiotherapy), menopausal status and the clinical question go in clinical_context; they select the checklist when the protocol alone is ambiguous.

The result

Section	Content
Rectal cancer staging	Tumour height, T stage, MRF/CRM distance, EMVI, nodes; mrTRG on restaging
Cervical cancer staging	Tumour size, parametrial and vaginal invasion, nodes, FIGO stage
Endometrial cancer staging	Depth of myometrial invasion, cervical stromal invasion, FIGO stage
Adnexal mass (O-RADS MRI)	Adnexal mass characterisation and O-RADS MRI score 1–5
Fibroids and adenomyosis	Fibroid count, size and FIGO type, uterine volume, adenomyosis flag
Endometriosis	Endometriomas, ovary segmentation, map of deep infiltrating endometriosis
Perianal fistula	Fistula tract classification, abscess and activity
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 uterus, fibroids and ovaries; SR TID 1500 for measurements; KOS key images and Encapsulated PDF. The FIGO stage is returned in a figo_stage block.
• Rectum: ESGAR 2016 consensus on rectal cancer MRI.
• Gynaecological oncology: FIGO 2018 for cervical cancer, FIGO 2023 for endometrial cancer.
• Benign gynaecology: FIGO leiomyoma classification (PALM-COEIN) and #Enzian for endometriosis.
• Adnexa: O-RADS MRI (ACR 2022).
• Perianal: Parks and St James's University Hospital classifications; MAGNIFI-CD activity index.
• Nodes: Node-RADS where nodal assessment applies.