The quantification of intracranial thrombus extent with the clot burden score predicts functional outcome, final infarct size and parenchymal hematoma risk acutely. The score needs external validation and could be useful for patient stratification in stroke trials.

Background and Purpose-The frequency of DWI negative cerebral ischemia and clinical factors associated with such a circumstance is not well understood. Methods-We performed MRI including diffusion-weighted imaging (DWI) in patients with stroke and transient ischemic attack (TIA) within 24 hours of symptom onset and again at 30 days. Results-Of 401 patients, 103 (25.6%) had an initial negative DWI study. In the DWI negative group, among the stroke patients, 6/26 (23.1%) had infarcts on follow-up MRI (4 lacunar and 2 posterior circulation syndromes) and 1 had a rMTT deficit. Among the TIA patients, 4/63 (6.3%) showed rMTT deficits and 2/63 (3.2%) had infarcts on follow-up MRI. Conclusions-Baseline perfusion weighted imaging sequences may detect ischemia in a small proportion of DWI negative cases. Only those with brain stem location or lacunar syndrome were DWI negative initially and yet had a follow-up imaging confirmation of infarct or a final clinical diagnosis of stroke. (Stroke. 2008;39:1898-1900.)

Background and Purpose-Minimal research has evaluated the renal safety of emergent computed tomography angiography (CTA) procedures, consecutive contrast medium application, and the long-term outcome in acute stroke patients. We investigated the incidence of contrast-induced renal impairment in these populations. Methods-We retrospectively reviewed patients with acute stroke syndrome who received a CTA of the brain with or without the neck within 24 hours from onset of symptoms. All creatinine results and additional conventional angiography findings were recorded. With a positive history of renal disease, contrast administration was delayed until creatinine results were available. Radiocontrast nephropathy (RCN) was defined as a Ն25% increase in serum creatinine from the baseline value up to 5 days after CTA. Results-Four hundred eighty-one patients were reviewed, and 224 met the inclusion criteria. There were 7 of 224 (3%) who fulfilled the criteria for RCN. A number of patients underwent emergent CTA without knowledge of their creatinine value; 2 of 93 (2%) developed RCN. There were 36 patients who received an additional digital subtraction angiogram, and none of these developed subsequent RCN. No patients required dialysis, and 9 of 68 (13%) had a Ͼ25% increase in their creatinine levels at a late (Ͼ30 days) follow-up. Conclusions-Overall, these results illustrate that there is a low incidence of RCN in acute stroke patients undergoing emergency CTA. Key Words: CT angiography Ⅲ digital subtraction angiography Ⅲ radiocontrast nephropathy Ⅲ renal impairment C omputed tomography (CT) bolus techniques have the advantage of minimizing treatment delays but require the use of a nonionic contrast agent. One apprehension surrounding these techniques is the concern of causing radiocontrast nephropathy (RCN). RCN is defined as an increase in the serum creatinine value by Ͼ25% occurring within 3 days after the administration of contrast medium. 1 First, the time from stroke onset to thrombolysis treatment is strongly associated with subsequent outcome in acute stroke. 2 In acute stroke when time is critical, treatment delay due to waiting for a creatinine result is not desirable. 3 Only 1 study has examined the rate of RCN in patients with unknown baseline creatinine levels. 4 Second, it is known that the risk for RCN is proportional to the dose of radiocontrast medium administered. [5][6][7] It has been suggested that multiple, consecutive procedures requiring the use of contrast medium application implies a greater risk for RCN. 8 There have been no large studies examining the safety of consecutive contrast media application in acute stroke for CT angiography (CTA) and digital subtraction angiography (DSA).Third, the long-term outcome in patients undergoing radiocontrast application is unknown. Although serum creatinine levels may return to baseline shortly after receiving contrast medium, some patients may encounter permanent renal sequelae requiring additional medical care. 9 This study sought to determine the freque...

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