Diffusion- and perfusion-weighted MR imaging of transient focal cerebral ischaemia in mice

Temporary focal ischaemia was induced in wild-type C57Black/6 mice by threa d occlusion of the middle cerebral artery (MCA). Recirculation was started after 60 min and maintained for 24 h, after which the mouse brain was froze n in situ. Development of the cerebral infarct was monitored by diffusion-, perfusion- and T-2-weighted magnetic resonance imaging (MRI) during ischae mia, during the early reperfusion period of 90 min, and at 24 h after reper fusion. Ischaemia caused a marked reduction of the perfusion signal intensi ty and of the apparent diffusion coefficient (ADC) of tissue water in the i psilateral MCA territory. In sham-operated control animals ADC remained unc hanged. Hemispheric lesion volume after 1 h MCA occlusion was 53 +/- 6% (n = 6), as defined by an ADC decrease of more than 20%. Recirculation reduced hemispheric lesion volume to only 27 +/- 13%, while there was a trend towa rds secondary lesion growth at 24 h, Post-ischaemic recovery of perfusion w as slow, heterogeneous and incomplete. A region-of-interest analysis showed only partial and transient recovery of the ADC, particularly in the dorsol ateral cortex and lateral caudate putamen, which may be explained by inadeq uate reperfusion in these regions. Detailed MRI studies of cerebral ischaem ia and reperfusion may now also be performed in the transgenic mice. Copyri ght (C) 1999 John Wiley & Sons, Ltd.