Quantitative T1 and T2 MRI signal characteristics in the human brain: different patterns of MR contrasts in normal ageing

Abstract

ObjectiveThe objective of this study was to examine age-dependent changes in both T1-weighted and T2-weighted image contrasts and spin-echo T2 relaxation time in the human brain during healthy ageing.MethodsA total of 37 participants between the ages of 49 and 87 years old were scanned with a 3 Tesla system, using T1-weighted, T2 weighted and quantitative spin-echo T2 imaging. Contrast between image intensities and T2 values was calculated for various regions, including between individual hippocampal subfields.ResultsThe T1 contrast-to-noise (CNR) and gray:white signal intensity ratio (GWR) did not change in the hippocampus, but it declined in the cingulate cortex with age. In contrast, T2 CNR and GWR declined in both brain regions. T2 relaxation time was almost constant in gray matter and most (but not all) hippocampal subfields, but increased substantially in white matter, pointing to an age effect on water relaxation in white matter.ConclusionsChanges in T1 and T2 MR characteristics influence the appearance of brain images in later life and should be considered in image analyses of aged subjects. It is speculated that alterations at the cell biology level, with concomitant alterations to the local magnetic environment, reduce dephasing and subsequently prolong spin-echo T2 through reduced diffusion effects in later life.Electronic supplementary materialThe online version of this article (doi:10.1007/s10334-016-0573-0) contains supplementary material, which is available to authorized users.

Age differences in head motion and estimates of cortical morphology

“…Thus, while AES is sensitive to an MR image property related to age, it seems to be distinct from fMRI-estimated head motion. A likely possibility is tht AES here is detecting age-related differences in gray/white matter contrast ratio (GWR), as have been previously observed (Knight et al, 2016; Magnaldi et al, 1993; Salat et al, 2009).…”

Regional T1 mapping of the whole cervical spinal cord using an optimized MP2RAGE sequence

“…1,2 The T 1 relaxation time, or spin-lattice relaxation time, is indeed tissue and field specific, and a growing amount of work supports the use of T 1 mapping as an in vivo marker of tissue microstructure in clinical and neuroscientific research, probing for instance disease-related tissue changes [3][4][5] or developmental plasticity and ageing. [6][7][8] Over the years, numerous MR techniques have been proposed and used to estimate T 1 values. 9 These include saturation-recovery 10 and inversion-recovery (IR) 11 -based measurements, Look-Locker 12 techniques and faster methods based on variable flip angles (VFAs), such as the VFA ultrashort echo time 13 and the driven-equilibrium single-pulse observation of T 1 (DESPOT1) method.…”

Leveraging Clinical Imaging Archives for Radiomics: Reliability of Automated Methods for Brain Volume Measurement

“…In addition to the reliability tests and after establishing the most reliable method, analyses were performed by using estimates from the most reliable method to study the effect of age and imager heterogeneity. The effect of age on GM and WM tissue intensity contrast in structural MR images was previously demonstrated by several studies (18,19). To evaluate the effect of age on the reliability of thick-section brain volume estimates, the following experiment was performed: ICCs between thick-and thin-section volume estimates were iteratively calculated starting with the 10 youngest patients (age, 1-4 years) and then sequentially adding the next-older patient to the group.…”

“…Although there was a marginal decline of ICC for GMV and WMV, all ICC values remained excellent. The decline in GMV and WMV reliability can be attributed to decreasing GM and WM tissue intensity contrast with age (18,19).…”