Comparative evaluation of weight-bearing cone beam CT arthrography and supine 3T MRI in knee osteoarthritis

To evaluate the agreement of cone-beam computed tomography arthrography (CBCTA) and magnetic resonance imaging (MRI) in detecting osteoarthritic changes of the knee.

This comparative study included 58 knee joints in 54 symptomatic subjects with suspicion of knee osteoarthritis (OA). The symptomatic joints were imaged using CBCTA and 3T MRI and graded using the MRI Osteoarthritis Knee Score (MOAKS). Agreement between modalities was assessed using prevalence and bias adjusted kappa (PABAK), percentages of exact (PEA) and close agreement (PCA) of ±1 in MOAKS grades and participant-specific comparisons.

CBCTA was performed with acceptable intra-articular concentration in 86.2 % (n = 50) knees in 48 subjects (68.6 % women, mean age 58.7 years). Definite tibiofemoral and patellofemoral OA was identified on MRI in 76 % (n = 38). For all cartilage lesions, PABAKs ranged between 0.80 and 0.96 (mean 0.90), with mean PEAs of 68.4 % and mean PCAs of 90.2 %. Full-thickness cartilage lesions demonstrated particularly strong agreement. Osteophyte detection yielded PABAKs between 0.92 and 0.98 (mean 0.95), mean PEA of 65.8 % and mean PCA of 99 %. For meniscal pathology, PABAKs ranged from 0.84 to 0.98 (mean 0.90), with mean PCA of 74.7 % and mean PEA of 81.7 %. For the anterior cruciate ligament, Baker cyst, and synovial hypertrophy, PABAKs were 0.97, 0.63, and 0.65, with high PEAs.

CBCTA demonstrates moderate to almost perfect agreement with 3T MRI for knee OA findings. Although 13.8 % of the arthrographies had failed in our study, CBCTA offers a practical alternative when MRI is contraindicated or unavailable.