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T1 and T2 relaxation times and iron concentrations were measured in 24 specimens of gray matter from fresh human and monkey brains at magnetic fields from 0.05 to 1.5 Tesla. Three different effects were found that correlate with iron content: a T1-shortening that falls off somewhat at high fields, a T2-shortening that is field-independent and thus important(More)
A retrospective analysis of 158 T1-weighted and T2-weighted MRI scans of normal brains at 0.5 and 1.5 Tesla was performed. Signal intensities in the frontal cortex, caudate nucleus, putamen, and globus pallidus were divided by those of frontal white matter; and these gray/white ratios were correlated with iron concentration, estimated from the anatomical(More)
A protein-encaged superparamagnetic iron oxide has been developed and characterized by using horse spleen apoferritin as a novel bioreactive environment. The roughly spherical magnetoferritin molecules, 120 A in diameter, are composed of a monocrystalline maghemite or magnetite core 73 A +/- 14 in diameter. Except for the additional presence of iron-rich(More)
T2 was measured in samples of human blood and monkey brain over a field range of 0.02-1.5 Tesla, with variable interecho times, and was compared with previous data on ferritin solutions (taken with the same apparatus). 1/T2 in deoxygenated blood increased quadratically with field strength, as noted previously, but in brain gray matter the increase was(More)
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