Bi-phase age-related brain gray matter magnetic resonance T1rho relaxation time change

Objectives: To investigate normative value and age-related change of brain magnetic resonance T1rho relaxation at 1.5 T. Methods: 20 males (age: 40.7+/-15.5 years, range: 22-68 years) and 22 females (age: 38.5 +/-14.8 years, range: 21-62 years), were scanned at 1.5 Tesla using 3D fluid suppressed turbo spin echo sequence. Regions-of-interests (ROIs) were obtained by atlas-based tissue segmentation and T1rho was calculated by fitting the mean value to monoexponential model. Correlation between T1rho relaxation of brain gray matter regions and age was investigated. Results: A regional difference among individual gray matter areas was noted; with hippocampus (98.37+/-5.37 msec) and amygdala (94.95+/-4.34 msec) have the highest measurement, while pallidum (83.81+/-5.49) and putamen (83.93+4.76) the lowest measurement. T1rho values decreased slowly (mean slope: -0.256) and significantly (p<0.05) with age in gray matter for subjects younger than 40 years old, while for subjects older than 40 years old there was no significant correlation between T1rho relaxation and age. Conclusion: T1rho relaxation demonstrates a bi-phase change with age in adults of 22-68 years.