The magnetization transfer effect in cerebral infarction.

PURPOSE To estimate the age of cerebral infarcts using magnetization transfer.

METHODS Twelve patients with radiographically and clinically documented cortical and subcortical cerebral infarctions underwent MR imaging on a 0.1T magnet. Magnetization transfer contrast images were generated by application of off-resonance pulses to every other repetition time on intermediate-weighted images. The magnetization transfer effect was calculated by obtaining an intensity value in the region of interest within the infarcted area.

RESULTS The data show a pattern in which the magnetization transfer effect decreases as the chronicity of the infarct increases. Infarcts less than 1 week old had an average magnetization transfer effect of 0.35. Those more than 1 week and less than 1 month old average 0.30. Infarcts more than 1 month and specifically those more than 1 year old averaged 0.16 or less.

CONCLUSION Magnetization transfer offers the potential to estimate the age of cerebral infarcts.