Clinical evaluation of femoral head cartilage damage using 5-Tesla MRI T2-mapping sequence—based on pathological specimens

Traditional imaging modalities like X-rays and conventional MRI lack sensitivity to detect early microscopic changes in cartilage damage, making them insufficient for evaluating early degenerative changes. exploring more sensitive imaging techniques to precisely quantify cartilage damage has become a key focus in current OA research. This study aimed to evaluate the degree of femoral head cartilage damage by quantifying the signal intensity of cartilage regions of interest (ROI) using the 5T MRI T2-mapping sequence and correlating it with Mankin pathological scores for cartilage damage. Patients diagnosed with hip osteoarthritis, avascular necrosis of the femoral head, or congenital hip dysplasia, who underwent total hip arthroplasty with pathological specimen collection, were enrolled between January 2023 and December 2023. On sagittal 5T MRI images, the acetabular center was identified, and the femoral head cartilage was divided into eight regions (A1–A8). Each region was further subdivided into three equal parts, resulting in a total of 24 ROIs. The signal intensity values for each ROI were measured. For pathological analysis, femoral head specimens were sagittally sectioned through the acetabular center, decalcified, and stained with Safranin O-Fast Green. Cartilage damage was assessed using the Mankin scoring system. The Mankin score served as the gold standard for cartilage damage, and a diagnostic standard for evaluating femoral head cartilage damage using the 5T MRI T2-mapping sequence was established. Receiver Operating Characteristic Curve (ROC) curve analysis was performed for validation. A total of 15 patients meeting the inclusion criteria were analyzed, encompassing 360 ROI regions. Based on Mankin scoring, the ROIs were classified into mild damage (245 regions), moderate damage (104 regions), and severe damage (11 regions). There was a statistically significant correlation between T2-mapping values and Mankin scores. Significant differences in T2-mapping values were observed among the different Mankin grades. ROC curve analysis showed the following thresholds for T2-mapping values: ≤43.6 for mild damage, > 43.6 and ≤ 75.6 for moderate damage, and > 75.6 for severe damage. In this pathology-based study, 5-Tesla MRI T2 mapping demonstrated a significant correlation with histological Mankin scores in femoral head cartilage. Quantitative T2 values increased progressively with the severity of cartilage degeneration, indicating that high-field T2 mapping is sensitive to compositional and microstructural alterations of articular cartilage at the tissue level. The proposed T2 thresholds allowed preliminary stratification of cartilage degeneration severity within this cohort.