ASPECT Scores and Lesion Location, Volume and Improvement in TPA treated Patients
Background: Early ischemic changes on head CT have been reliably recorded with ASPECT scores, but have not correlated with lesion volume. We studied the effect of ASPECT score on lesion volume and how acute recanalization affected late ASPECT score and lesion volume. Methods: We evaluated consecutive patients with MCA occlusion by TCD who received IV TPA. Patients were matched with respect to persistent occlusion (GRP1) or complete recanalization of the MCA and clinical improvement (NIH stroke scale (NIHSS)improvement >4)(GRP2). ASPECT scores were measured on the acute and a subsequent CT scan. Lesion volume was calculated using the (A * B *C)/2 method. NIHSS were measured at baseline and at 24 hours. Results:16 patients were studied. Baseline NIHSS were (mean±SD) 20 ± 4 vs 15 ± 7 (NS) and ASPECT scores were 8.4 ± 1.2 vs 8.6 ± 1.7 (NS) in GRP 1 and 2 respectively. Age and time to TPA were similar. The distribution and types of abnormalities in both ASPECT scores and groups were similar. In GRP 1, 24 hr NIHSS were higher (22± 7 vs 5 ± 7 p<0.05) and ASPECT scores tended to be lower (6.4 ± 1.7 vs 8.4 ± 2.2 p=0.054). Lesion volumes were higher in GRP 1 (172.8 ± 130 vs 15.9 ± 32.2 p<0.05). Baseline ASPECT score did not correlate with lesion volume or 24 hr NIHSS, whereas, outcome ASPECT score correlated with lesion volume (r=-0.74 p<0.01) and tended to correlate with 24 hr NIHSS (r=-0.46 p<0.10). The change in ASPECT correlated with lesion volume (r=-0.73 p<0.01). 62%of the total abnormalities in ASPECT scores were noted in the caudate, lentiform, insula, and thalamus. The lentiform was abnormal in 75%. Reversibility was seen in the insula(4 patients), and in one patient each in the caudate, lentiform and MCA2,3, and 4 for a total of 9 areas. Conclusion: Baseline ASPECT scores are very sensitive to MCA ischemia and the most common areas involved have relatively small tissue volumes. Outcome ASPECT scores may differ from baseline and correlate with lesion volume. Patients with improvement have smaller volumes of infarcted tissue in similar locations compared to non responders. Our study shows that early ischemic changes may not predict lesion volume due to the confounding effect of recanalization.