The effect of chlorpromazine and methylprednisolone on NMR relaxation times in the normal cat brain.

This small experimental study describes the effects on the NMR relaxation times in normal cat brain of a 5-day course of high dose methylprednisolone and, separately, a 1-month course of standard dose daily chlorpromazine. Methylprednisolone had no influence on T1 or T2 in these tissues, but chlorpromazine produced a transient fall of T1 of thalamus, and rise in T2 of white matter: both normalize after 4 weeks. The mechanism of these changes is unknown. It is concluded that these drugs should not interfere with the quantitative MRI monitoring of brain abnormalities in patients receiving them, although the unlikely occurrence of longer term effects of chlorpromazine has not been excluded.