Carr-Purcell (CP) T2 MRI with adiabatic pulses, acquired with varying interecho interval (τCP), was used to study the time course of T2 and relative dynamic-dephasing contrast in the rat brain. Exposure to 30 min of middle cerebral artery occlusion (MCAo) resulted in an irreversible increase in absolute CP-T2 relaxation times. This was not associated with signal change in the relative dynamic-dephasing images, as computed by subtracting short τCP CP-T2 images from long τCP images and normalizing for long τCP images. A day after MCAo strong CP-T2 hyperintensity and low apparent diffusion coefficient were evident in the striatum with a decline in relative dynamic-dephasing contrast. Low dynamic dephasing contrast prevailed in striatum until day 5 post-MCAo, returning to control levels with similar time course to normalizing T2 and diffusion. The present results show a novel behavior of dynamic-dephasing contrast in poststroke brain tissue, providing data to assess the age of infarction in association to T2 images.
- Dynamic-dephasing contrast