2005 Volume 33 Issue 1 Pages 30-34
Assessment of the viability of ischemic regions in hyperacute stroke is required for decision-making in thrombolytic therapy. We investigated the efficacy of apparent diffusion coefficient (ADC) in assessing tissue viability of ischemic regions. Subjects comprised 12 patients with middle cerebral artery M1 occlusion. Ten patients underwent intra-arterial thrombolysis and 2 patients received conservative therapies.
On acute diffusion-weighted images, affected regions were classified into 3 groups: hyperintense area (HA), slightly hyperintense area (SHA) or isointense area (IA). ADC ratio (rADC) was calculated and reperfusion was assessed for each area. The rADC values in SHAs (0.80±0.10) were significantly lower than those in IAs (0.99±0.11, p<<0.001) but were significantly higher than those in HAs (0.66±0.09, p<0.001). In recanalized areas, all HAs resulted in infarction, but no IAs resulted in infarction. All SHAs with rADC <0.77 resulted in infarction, and no SHAs with rADC≥0.77 resulted in infarction. Among reperfused areas, an rADC of 0.77 was the cutoff value between reversible and irreversible lesions (sensitivity, 100%; specificity, 100%). Among non-reperfused areas, no apparent rADC threshold was found between areas that became infarcted and that those did not.
In conclusion, the present results suggest that reversibility of ischemic lesions with slight signal hyperintensity on DWI can be quantitatively predicted by measuring rADC. Assessments based on ADC may be useful for determining indications for thrombolytic therapy.
