Ankle Sprain MRI Signs: ATFL, CFL, Deltoid, and Recovery Context

Grade 1 sprains show mild perifascicular edema on fat-suppressed proton-density sequences with fully intact ATFL fiber continuity. Grade 2 demonstrates partial-thickness tearing with interstitial signal hyperintensity on PD-fat-sat but a residual continuous ligament band. Grade 3 reveals complete fiber disruption — a wavy, thickened, or absent ATFL on axial PD images — often accompanied by CFL disruption and lateral talar dome bone contusion on STIR sequences. AI can help explain these grading terms, but your clinician must confirm the injury grade and discuss non-surgical or surgical treatment.

Axial proton-density fat-saturated (PD-FS) sequences at 3 mm slice thickness provide the highest sensitivity for ATFL and CFL signal abnormality. Coronal PD-FS images complement the axial plane by showing ligament width and caliber changes. A 3 T field strength with a dedicated ankle coil improves resolution. STIR sequences in all three planes are valuable for bone marrow edema and peroneal tendon sheath fluid, which co-exist in high-grade sprains.

Ottawa Ankle Rules guide initial X-ray use to exclude fracture. MRI is recommended when symptoms persist beyond 4–6 weeks despite conservative management, when clinical instability suggests syndesmotic injury, or when osteochondral lesion of the talar dome is suspected. AI-assisted MRI review adds value by simultaneously assessing ATFL, CFL, syndesmotic complex (AITFL, PITFL, IOM), peroneal tendons, and articular cartilage in a single study.