Purpose. The aim of this study was to assess the correlation of 3D time-of-flight MR angiography (TOF MRA) and contrast-enhanced MR angiography (CEMRA) for carotid artery stenosis evaluation at 3T. Material and Methods. Twenty-three patients (5？f, 18？m; mean age 61？y, age range 45–78？y) with internal carotid artery stenosis detected with ultrasonography were examined on a 3.0T MR system. The MR examination included both 3D TOF MRA and CEMRA of the carotid arteries. MR images were evaluated independently by two board-certified radiologists. Stenosis evaluation was based on a five-point scale. Stenosis grades determined by TOF and CEMRA were compared using Spearman’s rank correlation coefficient and the Wilcoxon test. Cohen’s Kappa was used to evaluate interrater reliability. Results. CEMRA detected stenosis in 24 (52%) of 46 carotids evaluated, while TOF detected stenosis in 27 (59%) of 46 carotids. TOF MRA yielded significantly higher results for stenosis grade in comparison to CEMRA ( ). Interrater agreement was very good for both TOF MRA ( ) and CEMRA ( ). Conclusion. At 3T, 3D TOF MRA should not be used as replacement for contrast-enhanced MRA of the carotid arteries, as it results in significantly higher stenosis grades. 1. Introduction Atherosclerotic disease of the carotid arteries has a high prevalence in patients aged over 50 and is a major cause of ischemic stroke [1, 2]. While digital subtraction angiography (DSA) is still viewed as the gold standard in carotid imaging, noninvasive imaging methods, including resonance angiography (MRA), computed tomography angiography (CTA), and ultrasonography, play an increasing role in the evaluation of carotid artery disease. In addition to being noninvasive, MRA does not utilize ionizing radiation. Currently MRA of the extracranial carotid arteries is mostly performed as contrast-enhanced angiography (CEMRA), after intravenous injection of gadolinium-based contrast agents. While MR contrast agents have very few side effects [3, 4], they may cause nephrogenic systemic fibrosis (NSF) in patients with renal insufficiency [5]. The awareness of this possible side effect of gadolinium-based contrast agents has led to increased interest in nonenhanced MRA in recent years [6]. The most widely used type of nonenhanced MRA is time-of-flight angiography (TOF). TOF has been routinely used for imaging the intracranial arteries for many years [7]. Due to improved hardware, TOF with good spatial resolution is now feasible for carotid artery imaging in a reasonable timeframe. While most MR examinations are still
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