Coronary arteries: three-dimensional MR imaging with fat saturation and magnetization transfer contrast

Magnetic resonance imaging of the coronary arteries is a particularly difficult task because of the small size of the vessels and the motion of the heart during the cardiac and respiratory cycles. The authors developed a non-breath-hold three-dimensional (3D) technique to accomplish this goal. Imaging was performed with voxel sizes of 1.50-4.50 mm3. This allows for excellent multiplanar reconstruction to view the coronary arteries from any angle. The short echo time usually makes blood isointense with surrounding tissue since inflow enhancement is weak with a thick-slab 3D method. This problem is overcome by applying fat saturation and magnetization transfer contrast techniques to suppress the signals of fat and myocardium surrounding the coronary arteries. Respiratory motion artifacts are reduced by taking four acquisitions and averaging the data. The authors acquired the first 3-10 cm of both the left and right coronary arteries in most cases in 7-10 minutes with single slab coverage. Acquisition of multiple slabs should further increase the length of coverage of the coronary arteries. Further improvements will occur when respiratory gating is used.