Barber PA, Demchuk AM, Hill MD, et al. The Probability of middle cerebral artery MRA flow signal abnormality with quantified CT ischaemic change: targets for future therapeutic studies (J Neurol Neurosurg Psychiatry 2004;75:1426–30). The following errors appeared in this article:

1. The median CT ASPECTS and DWI ASPECTS quoted in the article were both 8. These are incorrect and should be CT ASPECTS 9 and DWI ASPECTS 8;

2. Sixty-six per cent (95% CI 0.56–0.75) of the patients had CT ischaemic change, while 81% (95% CI 0.72–0.88) of the DWI scans identified areas of hyperintense signal (not 67% and 79% quoted in the article);

3. In figure 2 the numbers in parentheses on the x axis were incorrect. The correct numbers for each ASPECTS value are 10 (34), 9 (21), 8(12), 7 (11), 6 (12), and 5 (10).