Simultaneous T1 and T2 Brain Relaxometry in Asymptomatic Volunteers using Magnetic Resonance Fingerprinting

Abstract

Magnetic resonance fingerprinting (MRF) is a method of image acquisition that produces multiple MR parametric maps from a single scan. Here, we describe the normal range and progression of MRF-derived relaxometry values with age in healthy individuals. 56 normal volunteers (ages 11-71 years, M:F 24:32) were scanned. Regions of interest were drawn on T₁ and T₂ maps in 38 areas, including lobar and deep white matter, deep gray nuclei, thalami and posterior fossa structures. Relaxometry differences were assessed using a forward stepwise selection of a baseline model including either gender, age, or both, where variables were included if they contributed significantly (p<0.05). Additionally, differences in regional anatomy, including comparisons between hemispheres and between anatomical subcomponents, were assessed by paired t-tests. Using this protocol, MRF-derived T₁ and T₂ in frontal WM regions were found to increase in with age, while occipital and temporal regions remained relatively stable. Deep gray nuclei, including substantia nigra, were found to have age-related decreases in relaxometry. Gender differences were observed in T₁ and T₂ of temporal regions, cerebellum and pons. Males were also found to have more rapid age-related changes in frontal and parietal WM. Regional differences were identified between hemispheres, between genu and splenium of corpus callosum, and between posteromedial and anterolateral thalami. In conclusion, MRF quantification can measure relaxometry trends in healthy individuals that are in agreement with current understanding of neuroanatomy and neurobiology, and has the ability to uncover additional patterns that have not yet been explored.

Keywords: MR Fingerprinting; T1 mapping; T2 mapping; aging; relaxometry.

Figure 1.

Age distribution of all participants in the study.

Figure 2.

MRF-derived quantitative maps. (A) T₁, (B) T₂, (C), proton density, and (D) off-resonance maps from a single acquisition with duration of 30.8 s.

Figure 3.

ROI locations. (A) 1, superior frontal white matter; 2, centrum semiovale. (B) 3, frontal WM; 4, caudate nucleus; 5, putamen; 6, globus pallidus; 7, medial thalamus; 8, lateral thalamus; 9, internal capsule; 10, genu; 11, splenium; 12, parietal WM. (C) 13, substantia nigra; 14, red nucleus; 15, temporal WM; 16, occipital WM. (D) 17, middle cerebellar peduncle; 18, cerebellum; 19, dentate nucleus; 20, vermis; 21, pons.

Figure 4.

Regions with significant T₁ and T₂ correlation with age. (A) Regions with a significant linear relationship between T₁, T₂, and age. (B) Regions with a significant quadratic relation between relaxation parameters and age.

Figure 5.

Regions with significant age and sex effects. (A) Regions with significant linear age + sex effects; in these models, the slope of linear regression on age for men and women is similar but the intercepts are significantly different. (B) Regions with significant age × sex effect on T₂ relaxometry; in this model, the slope of linear regression on age between men and women is statistically significant.