Imaging of the brain in acute ischaemic stroke: comparison of computed tomography and magnetic resonance diffusion-weighted imaging

Abstract

Background and objectives: Controversy exists about the optimal imaging technique in acute stroke. It was hypothesised that CT is comparable with DWI, when both are read systematically using quantitative scoring. Methods: Ischaemic stroke patients who had CT within six hours and DWI within seven hours of onset were included. Five readers used a quantitative scoring system (ASPECTS) to read the baseline (b) and follow up CT and DWI. Use of MRI in acute stroke was also assessed in patients treated with tissue plasminogen activator (tPA) by prospectively recording reasons for exclusion. Patients were followed clinically at three months.Results: bDWI and bCT were available for 100 consecutive patients (admission median NIHSS = 9). The mean bDWI and bCT ASPECTS were positively related (p,0.001). The level of interrater agreement ranged from good to excellent across all modalities and time periods. Bland-Altman plots showed more variability between bCT and bDWI than at 24 hours. The difference between bCT and bDWI was (2 ASPECTS points. Of bCT scans with ASPECTS 8-10, 81% had DWI ASPECTS 8-10. Patients with bCT ASPECTS of 8-10 were 1.9 times more likely to have a favourable outcome at 90 days than those with a score of 0-7 (95% CI 1.1 to 3.1, p = 0.002). The relative likelihood of favourable outcome with a bDWI ASPECTS 8-10 was 1.4 (95% CI 1.0 to 1.9, p = 0.10). Of patients receiving tPA 45% had contraindications to urgent MRI. Conclusion: The differences between CT and DWI in visualising early infarction are small when using ASPECTS. CT is faster and more accessible than MRI, and therefore is the better neuroimaging modality for the treatment of acute stroke.

CT Angiography Source Images Predict Final Infarct Extent in Patients with Basilar Artery Occlusion

“…Therefore, our study reports 43 patients. Overall, 29 patients (67%) were men, median age was 67 years (range, 40 -90 years), baseline National Institutes of Health Stroke Scale (NIHSS) score was 22 (range, 0 -40), baseline Glasgow Coma Scale (GCS) score was 9 (range, [3][4][5][6][7][8][9][10][11][12][13][14][15], and onset-to-CTA time was 5 hours (range, 0.7-24 hours). We treated 6 patients with IV alteplase (rtPA); 7 patients with thrombolytic and/or mechanical IA therapy; and 22 patients with various combinations of IV (rtPA [n ϭ 11] or abciximab [n ϭ 11]) and IA therapies, respectively.…”

“…On follow-up NCCT, we applied pc-ASPECTS to regions of subacute brain infarction; on follow-up MR imaging, we scored hyperintense regions on DWI sequences. 15 If patients had both follow-up NCCT and MR imaging, we used the lower pc-ASPECTS score for analysis. Hemorrhagic transformation (HT) on follow-up images was classified as parenchymal hematoma (PH) or hemorrhagic infarction (HI) according to European Cooperative Acute Stroke Study criteria.…”

Accuracy of the Alberta Stroke Program Early CT Score during the First 3 Hours of Middle Cerebral Artery Stroke: Comparison of Noncontrast CT, CT Angiography Source Images, and CT Perfusion

“…Two weeks after all CT-based data were assessed, the same raters loaded and reviewed the follow-up DWIs from the prepared compact disks. By consensus, the raters evaluated each ASPECTS region for DWI hyperintensity 17 and associated restricted diffusion on the apparent diffusion coefficient maps. These abnormalities on DWI were recorded and served as the reference standard for regions of final infarct.…”

Evaluation of Initial Diffusion-weighted Image Findings in Acute Stroke Patients using a Semiquantitative Score

“…Barber and associates reported that ASPECTS values on DWI were lower than those on CT because of the higher sensitivity of DWI than CT in detecting acute ischemic lesion. 10 In this study, ASPECTS lower than 8 points in 3 of 16 patients in the non-deteriorated group re‰ected that DWI as compared with CT can overestimate lesion extent. In contrast, DWI scores less than 8 in 2 patients suggested that the 11-point system that adds a region of white matter to the original 10 regions in ASPECTS can compensate for the overestimation on DWI, although we failed toˆnd statistical signiˆcance between DWI and ASPECT scores.…”