Interregional variation of longitudinal relaxation rates in human brain at 3.0 T: relation to estimated iron and water contents.
In a study of interregional variation of the longitudinal relaxation rate (R(1)) in human brain at 3 T, R(1) maps were acquired from 12 healthy adults using a multi-slice implementation of the T one by multiple readout pulses (TOMROP) sequence. Mean R(1) values were obtained from the prefrontal cortex (0.567 +/- 0.020 sec(-1)), caudate head (0.675 +/- 0.019 sec(-1)), putamen (0.749 +/- 0.023 sec(-1)), substantia nigra (0.873 +/- 0.037 sec(-1)), globus pallidus (0.960 +/- 0.034 sec(-1)), thalamus (0.822 +/- 0.027 sec(-1)), and frontal white matter (1.184 +/- 0.057 sec(-1)). For gray matter regions other than the thalamus, R(1) showed a strong correlation (r = 0.984, P < 0.0001) with estimated regional nonheme iron concentrations ([Fe]). These R(1) values also showed a strong correlation (r = 0.976, P < 0.0001) with estimates of 1/f(w) obtained from MRI relative proton density measurements, where f(w) represents tissue water content. When white matter is included in the consideration, 1/f(w) is a better predictor of R(1) than is [Fe]. An analysis based on the fast-exchange two-state model of longitudinal relaxation suggests that interregional differences in f(w) account for the majority of the variation of R(1) across gray matter regions. Magn Reson Med 45:71-79, 2001.
Gelman
N
N
Department of Neurology, Henry Ford Hospital and Health Sciences Center, Detroit, Michigan 48202, USA.
Ewing
J R
JR
Gorell
J M
JM
Spickler
E M
EM
Solomon
E G
EG
D000328:Adult; D001834:Body Water; D001923:Brain Chemistry; D002540:Cerebral Cortex / Q000737:chemistry; D005260:Female; D005917:Globus Pallidus / Q000737:chemistry; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007501:Iron / Q000032:analysis*; D008279:Magnetic Resonance Imaging; D008297:Male; D019047:Phantoms, Imaging; D011699:Putamen / Q000737:chemistry; D013788:Thalamus / Q000737:chemistry
D007501:Iron