Method for reduced SAR T1rho-weighted MRI.
A reduced specific absorption rate (SAR) version of the T(1rho)-weighted MR pulse sequence was designed and implemented. The reduced SAR method employs a partial k-space acquisition approach in which a full power spin-lock pulse is applied to only the central phase-encode lines of k-space, while the remainder of k-space receives a low-power spin-lock pulse. Acquisition of high- and low-power phase-encode lines are interspersed chronologically to minimize average power deposition. In this way, the majority of signal energy in the central portion of k-space receives full T(1rho)-weighting, while the average SAR of the overall acquisition can be reduced, thereby lowering the minimum safely allowable TR. The pulse sequence was used to create T(1rho) maps of a phantom, an in vivo mouse brain, and the brain of a human volunteer. In the images of the human brain, SAR was reduced by 40% while the measurements of T(1rho) differed by only 2%. The reduced SAR sequence enables T(1rho)-weighted MRI in a clinical setting, even at high field strengths.
Wheaton
Andrew J
AJ
Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6100, USA. wheaton@seas.upenn.edu
Borthakur
Arijitt
A
Corbo
Matthew
M
Charagundla
Sridhar R
SR
Reddy
Ravinder
R
D000818:Animals; D001921:Brain / Q000033:anatomy & histology; D001931:Brain Mapping; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D019047:Phantoms, Imaging