Artifacts in magnetic resonance angiography

UNLABELLED: This study was aimed at assessing and classifying the incidence of Magnetic Resonance Angiography (MRA) artifacts using the 2D and 3D time-of-flight (TOF) technique. MATERIALS AND METHODS: from 300 MRA examinations performed January 1991 through April 1993, we selected the first 10 examinations for each vascular region which exhibited an artifact. Many kinds of artifacts were considered, i.e., hardware, sequence, magnetic susceptibility, patient and maximum intensity projection (MIP) artifacts. A superconductive 1.5-T magnet (Magnetom, Siemens) was used, with 2D and 3D TOF acquisitions. RESULTS: the quantitative analysis of artifact frequency showed that in the intracranial vessels (2D and 3D TOF sequences) the most common artifacts are saturation (30%) and magnetic susceptibility (30%) artifacts. As for neck vessels (3D TOF sequences), turbulence (40%) and lack of inclusion (30%) artifacts are the most common ones. In thoracic vessels (2D TOF sequences), MIP (50%) and ghost (30%) artifacts are the most common ones, while in the abdominal aorta (2D TOF sequences) magnetic susceptibility (20%), voluntary movement (20%), peristalsis (20%) and MIP (20%) artifacts occurred most frequently. Saturation (30%) and respiratory movement (30%) artifacts were the most common ones in the study of the renal arteries (3D TOF sequences), while MIP artifacts prevailed (40%) in the inferior vena cava (2D TOF sequences). Finally, MIP (40%) and patient movement (30%) artifacts were the most frequent ones in the study of the lower limbs (2 TOF sequences). CONCLUSIONS: in 2D and 3D TOF studies, being familiar with artifacts and their physical principles helps avoid image misinterpretation so that, if no technical means can prevent an artifact from occurring, at least it will not become a diagnostic pitfall.