B1+ Inhomogeneity Correction with Dielectric Padding for Improved MR T2 and T1ρ Quantification in Knee Cartilage and Meniscus at 7 Tesla

Motivation: MR T2 and T1ρ mapping showed great promise for reliable detection and follow-up of knee osteoarthritis, however, B1+ inhomogeneities in knee 7T MRI often lead to signal loss and biased quantification. Goal(s): Present study therefore evaluates the effect of high-permittivity dielectric padding on the B1+ field distribution and the reproducibility of T2 and T1ρ quantification in knee cartilage and meniscus. Approach: Twelve subjects received scan-rescan at 7T to quantify B0, B1+, T2, T1ρ, and reproducibility changes associated with dielectric padding. Results: Dielectric pads positioned over tibia showed improved B1+ homogeneity and reproducibility of T2 and T1ρ quantification in cartilage and meniscus at 7T. Impact: Improved reproducibility of T2 and T1ρ MRI in cartilage and meniscus with dielectric padding at 7T could facilitate its clinical translation at ultra-high field and improve patient’s follow-up for the noninvasive evaluation of new prevention and treatment strategies for osteoarthritis.