Modulated Repetition Time Look Locker (MORTLL): a Method for Rapid High Resolution Three Dimensional T1 Mapping

Neville Dali Gai¹, John Butman¹

A modification of the Look-Locker (LL) technique that enables high resolution T1 mapping over the physiologic range of intracranial T1 values is presented. The modifications include the use of a 3D balanced SSFP acquisition (for high SNR and resolution) along with variable repetition time to allow effective full recovery of longitudinal magnetization. The technique makes it possible to image a volume of thin contiguous slice with high resolution and accuracy using a simple fitting procedure for three LL phases in a reasonable time and is particularly well suited for imaging long T1 species. The T1 values obtained in WM, GM and CSF are compared with those obtained using inversion recovery spin echo imaging (gold standard) as well as with a 8 phase LL with a three parameter model and correction described in literature. T1 values obtained in multiple phantoms and from six volunteers showed excellent agreement with IR-SE T1 values.