To prospectively evaluate incidence of clinically silent and clinically apparent embolic cerebral infarction following diagnostic and interventional coronary angiography and associated risk factors. Written informed consent was obtained from all patients, and the study was approved by the research ethics committee of University of Heidelberg, Germany. Fifty-two patients, including 37 men (mean age, 66.1 years +/- 11.9 [standard deviation]) and 15 women (mean age, 65.3 years +/- 10.3), undergoing elective cardiac catheterization were examined 3-26 hours (mean, 15.3 hours +/- 6) before and 12-48 hours (mean, 25.9 hours +/- 10.4) after cardiac catheterization. Magnetic resonance imaging protocol included isotropic and anisotropic diffusion-weighted single-shot echo-planar sequences. T2-weighted turbo spin-echo and T1-weighted spin-echo sequences also were performed. Apparent diffusion coefficient maps were calculated to exclude false-positive reading results on diffusion-weighted images because of T2 shine-through effect. Images were assessed by two experienced radiologists blinded to clinical data. Cardiac catheterization was performed by 11 experienced cardiologists to exclude operator-related risk. A neurologic examination according to the National Institutes of Health Stroke Scale and Barthel index was performed by a senior cardiologist before acquisition of each image. Sixteen clinical and angiographic variables were analyzed with univariate analysis for ability to predict occurrence of cerebral infarction. No embolic cerebral lesions could be detected at diffusion-weighted imaging before catheterization. After coronary angiography, seven (15%) of 48 patients demonstrated nine focal cerebral infarcts affecting anterior and posterior circulation. Patients remained asymptomatic. Of all tested variables, only duration of the procedure was identified as an independent predictor of occurrence of cerebral infarction (P < .05). In this prospective study, asymptomatic cerebral infarction following cardiac catheterization occurred in 15% of patients in whom duration of the procedure was significantly longer than in those without infarction (P = .017). (c) RSNA, 2005.