T 1 ρ MRI quantification of arthroscopically confirmed cartilage degeneration

Nine asymptomatic subjects and six patients underwent T 1 ρ MRI to determine whether Outerbridge grade 1 or 2 cartilage degeneration observed during arthroscopy could be detected noninvasively. MRI was performed 2‐3 months postarthroscopy, using sagittal T 1 ‐weighted and axial and coronal T 1 ρ MRI, from which spatial T 1 ρ relaxation maps were calculated from segmented T 1 ‐weighted images. Median T 1 ρ relaxation times of patients with arthroscopically documented cartilage degeneration and asymptomatic subjects were significantly different ( P < 0.001), and median T 1 ρ exceeded asymptomatic articular cartilage median T 1 ρ by 2.5 to 9.2 ms. In eight observations of mild cartilage degeneration at arthroscopy (Outerbridge grades 1 and 2), mean compartment T 1 ρ was elevated in five, but in all observations, large foci of increased T 1 ρ were observed. It was determined that T 1 ρ could detect some, but not all, Outerbridge grade 1 and 2 cartilage degeneration but that a larger patient population is needed to determine the sensitivity to these changes. Magn Reson Med 63:1376–1382, 2010. © 2010 Wiley‐Liss, Inc.