MRI AND PATHOLOGICAL EXAMINATION OF POSTMORTEM BRAINS - THE PROBLEM OF WHITE-MATTER HIGH SIGNAL AREAS

We examined 21 brains from individuals more than 65 years of age by MR I and neuropathological methods to study the frequency and morphology of white matter changes. There were 16 brains from neurologically norm al subjects (Group 1) while the remaining 5 (Group 2) had neurological disturbances. In Group 1 MRI showed high signal areas in the perivent ricular white matter in 12 brains and in the deep white matter in 9. A ll had focal areas, with confluent zones in 4; 3 cystic infarcts were also detected. Neuropathology in this Group showed periventricular cha nges of variable extent in all cases, vacuolated myelin around the per ivascular spaces in 14 and degenerate myelin in 4. Macroscopic inspect ion showed 3 cystic lacunar infarcts, while areas of recent infarction were present on histology in 2. Four of the Group 2 brains had perive ntricular MRI changes; high signal areas in deep white matter were foc al in 2 and confluent in 1. Cystic infarcts were detected in 3 cases. Neuropathology showed periventricular changes in all the brains; in 4 myelin around the perivascular spaces was vacuolated while degenerate myelin was demonstrated in 1. There were also old (1) and recent (2) l acunar infarcts. High signal areas in the white matter thus have diffe rent histological backgrounds but only in a minority of cases do they seem to be of pathological significance and, as a rule, they are not r elated to the presence of neurological disturbances. Correlative MRI-n europathological studies are helpful for characterising abnormalities detected by techniques, like MRI, which are sensitive but not very spe cific.