Knee MRI

What it does

Knee MRI reads the highest-volume joint MRI, ordered for twisting injuries, locking, effusion and suspected osteoarthritis. The run takes the standard multiplanar protocol and works structure by structure, the way a musculoskeletal radiologist reads a knee: ligament, menisci, articular cartilage and subchondral bone.

It classifies the anterior cruciate ligament as intact, partially torn or completely torn with its secondary signs, locates meniscal tears by meniscus and horn and measures extrusion, segments the cartilage plates into a thickness map with focal defects, and describes bone marrow oedema and contusion patterns with lesion size. The result is organised one structure per section.

Intended use

Decision support for physicians reporting knee MRI: a structured checklist so that a meniscal root or posterior-horn tear is not overlooked on a busy list, and cartilage measurements that would take too long by hand. Every finding is shown on the image it was read from.

Who it is for

General and musculoskeletal radiologists and teleradiologists reading knee MRI, and orthopaedic and sports-medicine surgeons deciding between rehabilitation, arthroscopy and reconstruction. Developers use the cartilage segmentation and thickness maps for osteoarthritis research and longitudinal follow-up.

Accepted input

• DICOM MR study of one knee: MR Image, Enhanced MR or Legacy Converted Enhanced MR objects, zipped or sent by DICOMweb STOW-RS. NIfTI with a BIDS-style sidecar on the API.
• Clinical 2D protocols are the target; 3D cartilage sequences are also read for the cartilage section.
• The plane and fat suppression of each series are recognised from acquisition tags and the images.

Requirements

Requirement	Why
Sagittal and coronal PD or T2 fat-sat	ACL fibres, meniscal horns and body
Axial fat-sat sequence	Patellofemoral cartilage and a third plane for meniscal tears
Fluid-sensitive fat-sat sequences	Bone marrow oedema and contusion pattern
T1 (optional)	Marrow reference and fracture lines

A study without fat-suppressed fluid-sensitive images cannot be graded for marrow oedema; the result says so instead of returning an empty section.

Optional context

Mechanism of injury, the side, prior surgery (ACL reconstruction, meniscectomy) and the clinical question go in clinical_context. Prior surgery matters: graft and repaired-meniscus appearances are read differently from native tissue.

The result

Section	Content
Anterior cruciate ligament	Intact, partial tear or complete tear, with secondary signs
Menisci	Tear presence, medial or lateral meniscus, horn and location, extrusion
Cartilage	Cartilage segmentation, thickness map, focal defects with an ICRS or MOAKS-style grade
Bone marrow oedema	Bone marrow oedema and contusion pattern, bone marrow lesion size with a MOAKS-style grade
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 cartilage masks on the source series, SR TID 1500 for thickness and defect measurements, KOS key images and Encapsulated PDF.
• Grading: ICRS cartilage lesion grade; MOAKS-style grades for cartilage and bone marrow lesions, aligned with the WORMS/MOAKS semi-quantitative scoring used in osteoarthritis studies.
• Terminology: findings are coded with RadLex and SNOMED CT so they map to structured knee report templates.

How the sections relate

The ACL and meniscal sections answer the acute-injury question; cartilage and bone marrow lesions answer the degenerative one. A pivot-shift contusion pattern (lateral femoral condyle and posterolateral tibial plateau) is a secondary sign of an ACL tear, so the two sections are read together.