Human Knee: In Vivo T1_ρ-weighted MR Imaging at 1.5 T—Preliminary Experience

TLDR

A fast spin‑echo T1ρ‑weighted sequence on a 1.5‑T MR imager was used to measure knee joint relaxation times and compare T2‑ and T1ρ‑weighted images. T1ρ imaging revealed substantial dispersion in articular cartilage, a 25 % higher signal‑difference‑to‑noise ratio for chondral lesions compared to T2, and limited dispersion in muscle, suggesting it can depict cartilage and muscular abnormalities.

Abstract

A fast spin-echo sequence weighted with a time constant that defines the magnetic relaxation of spins under the influence of a radio-frequency field (T1ρ) was used in six subjects to measure magnetic resonance (MR) relaxation times in the knee joint with a 1.5-T MR imager. A quantitative comparison of T2- and T1ρ-weighted MR images was also performed. Substantial T1ρ dispersion was demonstrated in human articular cartilage, but muscle did not demonstrate much dispersion. T1ρ-weighted images depicted a chondral lesion with 25% better signal-difference-to-noise ratios than comparable T2-weighted images. This technique may depict cartilage and muscular abnormalities.