Fast whole brain relaxometry with Magnetic Resonance Spin TomogrAphy in Time-domain (MR-STAT) at 3 T: a retrospective cohort study

Objective: To report T1/T2-values of normal and normal appearing brain tissues (NBTs, healthy volunteers; NABTs, patients) acquired with a whole-brain 5-minute Magnetic Resonance Spin TomogrAphy in Time-domain (MR-STAT) protocol, and to explore relaxometry behavior in a brain tumor and in a multiple sclerosis patient. Methods: MR-STAT was acquired in 49 participants (39 patients with neurological pathologies, age range: 21–79 years) at 3 T. Mean T1/T2-values were computed for: normal and normal appearing grey matter (NGM/NAGM)/white matter (NWM/NAWM)/thalamus/putamen/caudate nucleus (CN)/globus pallidus (GP). Differences between sex, brain lobes, and left/right were assessed. The age-dependency of T1/T2-values in N(A)BTs was investigated. Relaxometry analysis was performed in two clinical case examples. Results: Mean (standard deviation) T1/T2-values were measured in N(A)GM = 1086(73)/74(9) ms; N(A)WM = 658(24)/48(3) ms; thalamus = 783(51)/42(4) ms; putamen = 863(40)/46(3) ms; CN = 1042(97)/63(9) ms; GP = 652(36)/36(3) ms. Differences between sex were not significant. T1/T2-values between the left/right parietal lobe and the left/right temporal lobe were significantly different. The quadratic age-dependency of T1-values in the CN (p = 0.00039) and GP (p = 0.00037), and of T2-values in the thalamus (p = 0.00044) and GP (p = 0.003) were significant. Pathological tissues could be discerned from NABTs using T1/T2-values. Discussion: T1/T2-values and data trends agree with literature, supporting the validity of MR-STAT as a clinical option for fast relaxometry despite the relatively low number of subjects in the study. Future work should aim to include healthy participants of a wider age-range and to include B1-field corrections.