Comparison of surface microscopy coil and ankle joint special phased array coil magnetic resonance imaging in assessing preoperative osteochondral lesions of the talus.

Background: Lesion size is a major determinant of treatment strategies and predictor of clinical outcomes for osteochondral lesions of the talus (OLTs). Although magnetic resonance imaging (MRI) has been commonly used in the preoperative evaluation of OLTs, MRI has low reliability and usually overestimates or underestimates lesion size compared with intraoperative assessment. This study aims to determine whether the surface microscopy coil (SMC) can improve the accuracy of assessment of preoperative OLTs compared with conventional coil MRI, ankle joint special phased array coil (ASC).

Methods: A total of 43 patients diagnosed with OLTs undertook preoperative MRI examination with both SMC and ASC were included in this prospective study from 2019 to 2022. The diameter of the lesion was measured in sagittal plane and coronal plane at its widest point and then the lesion area was calculated. Then MRI measurements were compared with arthroscopy or open-surgery measurements.

Results: The mean lesion area measured with ASC was significantly greater than that measured intraoperatively (95.07±44.60 . 52.74±29.86 mm, P<0.001), while there was no significant difference between lesion area measured in SMC and intraoperatively (55.28±36.06 . 52.74±29.86 mm, P=0.576). Diameter measured in ASC was significantly greater than that measured intraoperatively in both coronal plane (8.95±2.48 . 6.67±1.81, P<0.001) and sagittal plane (13.12±3.76 . 9.58±3.98, P<0.001). No significant difference between lesion diameter measured in SMC and intraoperatively in both coronal plane (6.44±2.59 . 6.67±1.81, P=0.608) or sagittal plane (10.23±3.69 . 9.58±3.98, P=0.194). Compared with surgical assessment, 39 of 43 cases were consistent with SMC assessment while only 26 of 43 cases were consistent with ASC assessment (39/43 . 26/43, P=0.002).

Conclusions: Diameter measured with SMC was much more accurate than ASC MRI. Compared with ASC MRI, the SMC had a much higher concordance rate between preoperative assessment and surgical assessment.