Preoperative 7 T 3D Meniscal T2* Mapping Correlates With Postoperative Extrusion After Medial Meniscus Posterior Root Tear Repair.

Medial meniscus posterior root tear (MMPRT) repairs stabilize root attachment and yield improved clinical outcomes, yet many patients develop persistent meniscal extrusion and osteoarthritis. This study evaluates menisci in MMPRT patients using 3D T2* mapping and assesses T2* correlation with medial meniscal extrusion. Patients underwent 7 T knee MRI before root tear repair and again at 6-month postoperative follow-up. Age- and gender-matched controls were scanned once. The protocol included clinical turbo-spin-echo sequences and a quantitative 3D GRE sequence, used to calculate T2* mapping of the menisci. Pre- and postrepair meniscal extrusion was measured on coronal T2-weighted images by two independent radiologists. Twenty-five patients (mean age 53 ± 8 years) and nine controls (51 ± 11 years) were included. Repairs were intact on follow-up MRI in all patients. T2* values were significantly elevated in patients both pre- and postrepair compared with controls across medial and lateral meniscal subregions. Medial meniscal extrusion increased from 3.7 ± 1.1 mm at baseline to 4.9 ± 1.5 mm (p = 0.002), postoperatively. Prerepair meniscal T2* strongly correlated with postrepair extrusion (ρ = 0.765; p < 0.001). High-resolution 3D T2* mapping at 7 T revealed persistently elevated T2* values after MMPRT repair, consistent with ongoing collagen fiber disorganization. Prerepair T2* values were strongly correlated with early postrepair meniscal extrusion despite MRI-intact repairs, indicating that preoperative tissue quality is associated with postoperative outcomes. These findings support quantitative T2* mapping as a prognostic imaging biomarker that complements conventional morphologic MRI in the evaluation of MMPRTs.