Optimization of human meniscus imaging using minimal phase RF pulse

Human meniscus is one of the important tissues related to the maintenance of the performance of knee joint, which plays a critical role in the normal biomechanics in load bearing, load distribution, and so forth [1]. Degeneration of human meniscus correlated strongly with the progression of osteoarthritis (OA) [2]. As a result, obtaining regional information of the menisci is helpful to clinical diagnosis and treatment. However, MR imaging of human meniscus is challenged by zonal heterogeneity due to variations in both fiber orientations and blood supply, as well as the short T2 value ranging from 5-8 msec at 1.5 T resulting from strong dipolar interaction in collagen molecules [3]. Ultra-short echo time (UTE) imaging provides a remedy to the latter issue [4], but the high signal intensity of menisci along with long-T2 suppression in UTE imaging does not provide clear distinction between the longer T2 and short T2 components. Therefore, the purpose of this study is to improve the zonal image contrast of human meniscus via imaging at moderately short TE using minimal phase RF pulse with optimized rephasing gradient.