Measurement of NMR relaxation times using the minimum number of scans.

NMR relaxation time measurements derived from a set of three multi-slice sequences (which can examine the whole brain in 30 min) have been investigated. T1 and T2 values are 5% and 20% too short, respectively. Noise in the measurements was less than 2%. Temporal instability was negligible. Spatial non-uniformity was 1% (T1) and 3% (T2) within a single slice but 4% (T1) and 14% (T2) from slice to slice. Variations in cerebral tissue measurements have also been investigated: T1 varies by 6% and T2 by 12% over a population of normal controls. There can be significant patient-patient and topographical variations.