T1ρ relaxation time in brain regions increases with ageing: an experimental MRI observation in rats.

Abstract

OBJECTIVE: T1&#x3c1; variation is associated with neurodegenerative diseases. This study aims to observe T1&#x3c1; relaxation time changes in rat brains associated with normal ageing in Sprague-Dawley (SD) rats, Wistar Kyoto (WKY) rats and spontaneously hypertension rats (SHRs). METHODS: 18 male SD rats, 11 male WKY rats and 11 male SHRs were used. T1&#x3c1; measurement was performed at 3-T MR with a spin-lock frequency of 500&#x2009;Hz. SD rats were scanned at the ages of 5, 8, 10 and 15 months. SHRs and WKY rats were scanned at the ages of 6, 9 and 12 months. RESULTS: For SD rats, T1&#x3c1; at the thalamus, hippocampus and frontal cortices increased significantly from 5 to 15 months (p&#x2009;<&#x2009;0.05). For the WKY rats and SHRs, the T1&#x3c1; values in the thalamus, hippocampus and frontal cortices also increased significantly from 6 to 12 months (p&#x2009;<&#x2009;0.05). Furthermore, T1&#x3c1; in the thalamus, hippocampus and frontal cortices of SHRs were consistently higher than those of WKY rats at the ages of 6, 9 and 12 months (p&#x2009;<&#x2009;0.05). The percentage regional T1&#x3c1; differences between WKY rats and SHRs did not change during ageing. CONCLUSION: An increase in T1&#x3c1; was associated with age-related changes of the rat brain. ADVANCES IN KNOWLEDGE: An age-related and hypertension-related T1&#x3c1; increase in rat brain regions was observed in the thalamus, hippocampus and frontal cortical regions of the rat brain.