T2∗ mapping of hip joint cartilage in various histological grades of degeneration

SummaryObjectiveTo evaluate T2∗ values in various histological severities of osteoarthritis (OA).MethodMagnetic resonance imaging (MRI) and T2∗ mapping including a three-dimensional (3D) double-echo steady-state (DESS) sequence for morphological cartilage assessment and a 3D multiecho data image combination (MEDIC) sequence for T2∗ mapping were conducted in 21 human femoral head specimens with varying severities of OA. Subsequently, histological assessment was undertaken in all specimens to correlate the observations of T2∗ mapping with histological analyses. According to the Mankin score, four grades of histological changes were determined: grade 0 (Mankin scores of 0–4), grade I (scores of 5–8), grade II (scores of 9–10), and grade III (scores of 11–14). For reliability assessment, cartilage T2∗ measurements were repeated after 4 weeks in 10 randomly selected femoral head specimens.ResultsT2∗ values decreased significantly with increasing cartilage degeneration (total P-values <0.001) ranging from 36.3 ± 4.3 ms in grade 0 regions to 22.8 ± 4.3 ms in regions with grade III changes. Pearson correlation analysis proved a fair correlation between T2∗ values and Mankin score (correlation coefficient = −0.362) that was statistically significant (P-value <0.001). Intra-class correlation (ICC) analysis demonstrated high intra-observer reproducibility for the T2∗ measurement (ICC: 0.949, P < 0.001).ConclusionsGiven the advantages of the T2∗ mapping technique with no need for contrast medium, high image resolution and ability to perform 3D biochemically sensitive imaging, T2∗ mapping may be a strong addition to the currently evolving era of cartilage biochemical imaging.