[Nuclear magnetic resonance study of brain edema in immature rats compared with adult rats].

Traumatic cerebral edema was experimentally produced in immature Wistar strain rats aged 7 days (Group A), and then edematous cerebrums were lyophilized. The water content was measured by the dry weight method. The longitudinal relaxation time (T1) and transverse relaxation time (T2) were measured on the NMR spectrometer. In respect to the measured water content and the relaxation time, changes with time were compared with those in matured rats aged 5 weeks (Group B). In the Group A, the water contents of the gray matter (G), the white matter (W), and the brain stem (BS) increased significantly over the period ranging from 6 to 16 days after the experimental production of cerebral edema. In the Group B, the water contents of G and W also increased significantly one day after the experimental production of cerebral edema. One day after development of the experimental edema, T1 was 1.770 +/- 0.131 sec (G) and 1.752 +/- 0.131 sec (W) in the Group A, while it was 1.451 +/- 0.003 sec (G) and 1.353 +/- 0.011 sec (W) in the Group B. On the other hand, T2 was 96.95 +/- 11.98 msec (G) and 92.80 +/- 8.78 msec (W) in the Group A, while it was 57.90 +/- 1.32 msec (G) and 58.50 +/- 0.98 msec (W) in the Group B. In other words, the relaxation time was significantly prolonged in the Group A. The extent of the prolongation was insignificant in the Group B considering the base line. T2 is assumed to be divided into two components in the cerebral tissues when cerebral edema develops.(ABSTRACT TRUNCATED AT 250 WORDS)