T 1 and T 2 quantification from standard turbo spin echo images

• Published in: Magnetic resonance in medicine Vol. 81; no. 3; pp. 2052 - 2063
• Main Authors: McPhee, Kelly C., Wilman, Alan H.
• Format: Journal Article
• Language: English
• Published: United States 01.03.2019
• Subjects: Adult; Algorithms; Brain - diagnostic imaging; Computer Simulation; Female; Gray Matter - diagnostic imaging; Humans; Image Processing, Computer-Assisted - methods; Magnetic Resonance Imaging; Male; Reference Values; Reproducibility of Results; White Matter - diagnostic imaging; Young Adult; relaxometry; turbo spin echo; T1; T2
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.27495

To extract longitudinal and transverse (T and T ) relaxation maps from standard MRI methods. Bloch simulations were used to model relative signal amplitudes from standard turbo spin-echo sequences: proton density weighted, T -weighted, and either T -weighted fluid attenuated inversion recovery or T -weighted images. Simulations over a range of expected parameter values yielded a look-up table of relative signal intensities of these sequences. Weighted images and flip angle maps were acquired in 8 subjects at 3 T using both single and multislice acquisitions. The T and T maps were fit by comparing the weighted images to the look-up table, given the measured flip angles. Results were compared with inversion recovery and multi-echo spin-echo experiments. A region analysis showed that relaxation maps computed from single-slice proton density, T and T weighting provided a mean T error of 4% in gray matter and 11% in white matter, and a mean T error of 3% and 4%, respectively, in comparison to reference measurements. In multislice acquisitions that are optimized to reduce cross-talk and incidental magnetization transfer, the mean T error was 7% in gray matter and 1% in white matter, and the mean T errors were 3% and 4%, respectively. The best T results were achieved using proton density, T and T weighting rather than the fluid attenuated inversion recovery, although T maps were largely unaffected by this choice. Incidental magnetization transfer reduced T accuracy in standard interleaved multislice acquisitions. Through exact sequence modeling and separate flip angle measurement, T and T may be quantified from a turbo spin-echo brain protocol with proton density, T , and T weighting.