- OBJECTIVE: Respiratory motion degrades MR images of the coronary arteries. The purpose of this study was to assess and compare two methods of reducing the effects of respiration in coronary artery MRI. Single-slice 2D imaging with breath-holding and a respiratory-gated 3D technique were used. MATERIALS AND METHODS: A comparison was made in 10 normal subjects between a 2D multiple breath-holding approach and a 3D technique with and without retrospective respiratory gating in imaging the coronary arteries. RESULTS: Respiratory gating improved the image quality in 76% of the 3D images. Both the 2D and the 3D approaches were capable of visualizing the proximal parts of the coronary arteries, with comparable vessel length and diameter. The image quality was somewhat better for images obtained by breath-holding in 83% of the vessels, probably due to less blurring by remnant respiratory motion and higher inflow contrast. CONCLUSION: The 2D breath-holding approach reveals a better image quality. However, the 3D respiratory-gated acquisition is less operator dependent, faster, and less strenuous for patients.