[Magnetic resonance imaging of coronary artery lesions using modified spin-echo sequence]

Magnetic resonance imaging of the cardiovascular system has been beset with difficulties in obtaining clear images due to prominent artifacts which course in the direction of the phase encoding axis. These artifacts are commonly believed to derive from blood flow. However, in the ECG-gated spin-echo (SE) sequence using two-dimensional Fourier transform reconstruction, variation in effective repetition time due to physiological changes in the R-R interval of ECG may also result in prominent artifacts. To eliminate these artifacts, we developed a new method, the modified spin-echo (MSE) sequence, by adding a nonselective 90 degree radio-frequency pulse and an optional delay time (Td) prior to the conventional SE sequence. In the MSE sequence, artifacts derived from the cardiovascular system were markedly suppressed. Using the MSE sequence, we attempted direct imaging of the coronary vessels, and obtained very clear images of the coronary arteries and veins. Organic lesions in the coronary arteries were also clearly imaged, including coronary stenosis, dilatation, coronary fistulae, and abnormality of the origin of the right coronary artery. The MSE sequence may offer a clinical advantage in obtaining coronary artery images, and may be used to evaluate coronary artery disease.