Dynamic contrast-enhanced MR angiography and MR imaging of the carotid artery: high-resolution sequences in different acquisition planes.

BACKGROUND AND PURPOSE First-pass contrast-enhanced MR angiography has become the technique of choice for studying the carotid bifurcation, but this method has some limitations. We evaluated the clinical utility of performing 3D contrast-enhanced MR angiography in the axial plane immediately after performing angiography in the coronal plane. METHODS Cervical carotid arteries of 80 consecutive patients were studied on a 1.5-T MR imager with phased-array coils. Coronal 3D MR angiography was performed after administering a bolus injection of contrast material (20 mL) with automatic triggering. This was immediately followed by an axial acquisition. We measured carotid diameters on the contrast-enhanced MR angiograms as well as on intra-arterial digital subtraction angiograms according to established criteria. We also evaluated original source MR angiograms. RESULTS Angiograms obtained in the axial plane correlated better with the intra-arterial digital subtraction angiograms than did the coronal angiograms. When first-pass contrast-enhanced MR angiography was incomplete because of a failure of triggering, the second-phase acquisition provided sufficient image quality. Original source images suffered from ring artifacts, low axial resolution, and a low level of soft-tissue visualization. Axial-based source images showed flow-independent contrast filling to the patent lumen with sufficient visualization of plaque morphology, thickened arterial wall, and surrounding disease processes, such as tumors. CONCLUSION With the addition of a 1-minute second-phase 3D acquisition in a different plane immediately after first-pass contrast-enhanced MR angiography, one can obtain a more accurate depiction of the carotid bifurcation, insurance against failure of triggering, and diagnostic source images.