MR imaging of human brain at 3.0 T: preliminary report on transverse relaxation rates and relation to estimated iron content.
OBJECTIVE
To determine the transverse relaxation rates R2 and R2' from several gray matter regions and from frontal cortical white matter in healthy human brains in vivo and to determine the relationship between relaxation rates and iron concentration [Fe].


METHODS
Six healthy adults aged 19-42 years underwent thin-section gradient-echo sampling of free induction decay and echo magnetic resonance (MR) imaging at 3.0 T. Imaging covered the mesencephalon and basal ganglia.


RESULTS
Relaxation rates (mean +/- SD) were highest in globus pallidus (R2 = 25.8 seconds-1 +/- 1.1, R2' = 12.0 seconds-1 +/- 2.1) and lowest in prefrontal cortex (R2 = 14.4 seconds-1 +/- 1.8, R2' = 3.4 seconds-1 +/- 1.1). Frontal white matter measurements were as follows: R2 = 18.0 seconds-1 +/- 1.2 and R2' = 3.9 seconds-1 +/- 1.2. For gray matter, both R2 and R2' showed a strong correlation (r = 0.92, P < .001 and r = 0.90, P < .001, respectively) with [Fe]. Although the slopes of the regression lines for R2' versus [Fe] and for R2 versus [Fe] were similar, the iron-independent component of R2' (2.2 seconds-1 +/- 0.6), the value when [Fe] = 0, was much less than that of R2 (12.7 seconds-1 +/- 0.7).


CONCLUSIONS
The small iron-independent component R2', as compared with that of R2, is consistent with the hypothesis that R2' has higher iron-related specificity.
Gelman
N
N
Department of Neurology, Henry Ford Hospital and Health Sciences Center, Detroit, MI 48202, USA.
Gorell
J M
JM
Barker
P B
PB
Savage
R M
RM
Spickler
E M
EM
Windham
J P
JP
Knight
R A
RA
D000328:Adult; D001479:Basal Ganglia / Q000033:anatomy & histology / Q000737:chemistry; D001921:Brain / Q000033:anatomy & histology*; D001923:Brain Chemistry; D002421:Caudate Nucleus / Q000033:anatomy & histology / Q000737:chemistry; D005260:Female; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000737:chemistry; D005917:Globus Pallidus / Q000033:anatomy & histology / Q000737:chemistry; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007501:Iron / Q000032:analysis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008636:Mesencephalon / Q000033:anatomy & histology / Q000737:chemistry; D011699:Putamen / Q000033:anatomy & histology / Q000737:chemistry; D012012:Red Nucleus / Q000033:anatomy & histology / Q000737:chemistry; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D013378:Substantia Nigra / Q000033:anatomy & histology / Q000737:chemistry
D007501:Iron