2021 Volume 12 Issue 2 Pages 113-120
Advanced osteoarthritis (OA) of the ankle is often accompanied by arthritic changes in the subtalar joint, and when arthrodesis is performed for ankle OA, the subtalar joint symptoms remain or even worsen. If the degree of subtalar cartilage degeneration can be quantified, prognosis can be predicted. T1ρ mapping has proven useful for identification of early cartilage degeneration. We hypothesized that T1ρ values of subtalar joint cartilage are higher (i.e., cartilage degeneration is greater) in patients with ankle OA without plain radiographic evidence of subtalar joint space narrowing and osteophytes than in healthy individuals. The T1ρ value of full thickness subtalar joint cartilage was measured on sagittal MR images obtained from 12 patients with ankle OA (3 with Takakura stage 3a disease and 9 with Takakura stage 3b disease) and from 12 healthy individuals. Imaging was performed with a 3.0 T MRI scanner, and PRIDE was used to construct T1ρ maps. A region of interest was set on the water-selective excitation image, which was projected onto the corresponding slice of the T1ρ mapping image to calculate the T1ρ value. The T1ρ value of the subtalar cartilage in patients with ankle OA (41.8 [39.8, 44.4] ms) did not differ significantly from that in healthy individuals (45.0 [37.0, 50.2] ms) (p=0.219 by Mann-Whitney U test). Our findings suggest that the T1ρ value of subtalar articular cartilage in patients with stage 3a or 3b ankle OA for whom conventional imaging reveals no OA changes does not differ significantly from that of healthy individuals.
