3D whole-heart coronary MR angiography (MRA) with SSFP at 1.5 T : a comparison with coronary MRA using Gd-enhanced FLASH sequences

Abstract

[한글]

[영문]Purpose: To determine the optimal cardiac phase and appropriate acquisition window for 3D whole-heart coronary magnetic resonance angiography (MRA) with a steady-state free precession (SSFP) sequence, and to compare image quality and detection rates between SSFP and Gd-enhanced fast low-angle shot (FLASH) MR techniques at 1.5T.Methods: Thirty healthy volunteers (25 men and 5 women; mean age, 35 years, range, 24-54 years) underwent coronary MRA at 1.5T. 3D whole-heart coronary MRA with an SSFP was performed three times: 1) at end-systole with a narrow (120 msec) acquisition window (ESN), 2) mid-diastole with narrow acquisition (MDN); and 3) mid-diastole with wide (170 msec) acquisition (MDW). Gd-enhanced coronary MRA with FLASH was performed during MDN. Visibility of the coronary artery and image quality were evaluated for 11 segments, as suggested by the American Heart Association (AHA). Image quality was scored by a five-point scale (1 = not visible to 5 = excellent). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were evaluated at the proximal coronary arteries.Results: The SSFP sequence gave higher detection rates in coronary artery segments, higher SNR and CNR, and higher image quality than the Gd-enhanced FLASH technique at 1.5T (p < 0.05). The narrow acquisition window at mid-diastole with SSFP gave a relatively high image quality and excellent SNR, although it required more scan time. Imaging with an SSFP at end-systole showed results similar to those at mid-diastole for coronary artery detection rates and image quality.Conclusion: The use of contrast material did not improve the detection rate, SNR, CNR or image quality on the 3D whole-heart coronary MRA at 1.5T. The optimal cardiac phase, either at mid-diastole or at end-systole, may be determined from the patient’s heart rate.