title: Optimized efficient liver T(1ρ) mapping using limited spin lock times.
abstract: T(1ρ) relaxation has recently been found to be sensitive to liver fibrosis and has potential to be used for early detection of liver fibrosis and grading. Liver T(1ρ) imaging and accurate mapping are challenging because of the long scan time, respiration motion and high specific absorption rate. Reduction and optimization of spin lock times (TSLs) are an efficient way to reduce scan time and radiofrequency energy deposition of T(1ρ) imaging, but maintain the near-optimal precision of T(1ρ) mapping. This work analyzes the precision in T(1ρ) estimation with limited, in particular two, spin lock times, and explores the feasibility of using two specific operator-selected TSLs for efficient and accurate liver T(1ρ) mapping. Two optimized TSLs were derived by theoretical analysis and numerical simulations first, and tested experimentally by in vivo rat liver T(1ρ) imaging at 3 T. The simulation showed that the TSLs of 1 and 50 ms gave optimal T(1ρ) estimation in a range of 10-100 ms. In the experiment, no significant statistical difference was found between the T(1ρ) maps generated using the optimized two-TSL combination and the maps generated using the six TSLs of [1, 10, 20, 30, 40, 50] ms according to one-way ANOVA analysis (p = 0.1364 for liver and p = 0.8708 for muscle).
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People's Republic of China. jyuan@cuhk.edu.hk
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.forename: Feng
authors.initials: F
authors.lastname: Zhao
authors.forename: James F
authors.initials: JF
authors.lastname: Griffith
authors.forename: Queenie
authors.initials: Q
authors.lastname: Chan
authors.forename: Yi-Xiang J
authors.initials: YX
authors.lastname: Wang
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D003198:Computer Simulation; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008099:Liver / Q000033:anatomy & histology* / Q000473:pathology; D008103:Liver Cirrhosis / Q000175:diagnosis / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D023421:Models, Animal; D009010:Monte Carlo Method; D051381:Rats; D017207:Rats, Sprague-Dawley