Multimodal magnetic resonance imaging of the vastus medialis for quantitative diagnosis and grading in early-stage knee osteoarthritis and its correlation with severity

Early-stage knee osteoarthritis (EKOA) requires timely diagnosis. The recent diagnostic criteria for EKOA by the bone and joint branch of the Chinese geriatric care association remain limited. These limitations necessitate the development of novel, clinical non-invasive imaging modalities to quantitatively evaluate knee joint structures and improve diagnostic accuracy in EKOA. We aimed to investigate whether the quantitative parameters of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and fat analysis calculation technique (FACT) may differentiate between patients with EKOA and healthy controls, as well as evaluate the correlations of the parameters with X-ray Kellgren–Lawrence (KL) grading and Visual Analog Scale (VAS). We analyzed 207 knee joints of 168 participants, including 62 from healthy controls (control group) and 145 from patients with EKOA (observation group: excluding those with other combined knee joint diseases or underlying diseases); the observation group was categorized into three subgroups based on the KL grading system. Age and body mass index (BMI) exhibited no significant differences between the two groups. Although age and BMI showed slight variations across the KL subgroups, the differences were not statistically significant. IVIM-DWI (diffusion coefficient [D], pseudo-diffusion coefficient [D*], and perfusion fraction [f]) and FACT (fat fraction [FF]) parameters were acquired in the vastus medialis using a 3.0T magnetic resonance imaging (MRI) scanner. Intergroup comparisons of IVIM-DWI and FACT parameters were conducted, and subgroup differences and correlation between the IVIM-DWI and FACT parameters and radiographic KL grades were assessed. The observation group showed higher D, D*, and FF values than did the control group; however, the f values were lower in the observation group. Within the observation group, Grade II knees had higher D and FF values than did Grade 0 and I knees, as well as lower f values than did Grade 0 knees. D and FF values showed a moderately positive correlation with both KL grades and VAS scores, whereas f values showed a weak negative correlation with both. IVIM-DWI and FACT may provide biological information of improved sensitivity and accuracy for the quantitative diagnosis of EKOA at the microstructural level in the vastus medialis.