MR-imaging of the thoracic aorta: 3D-ECG- and respiratory-gated bSSFP imaging using the CLAWS algorithm versus contrast-enhanced 3D-MRA.

OBJECTIVE: To compare a contrast-enhanced 3D angiography (CE-3D-MRA) with the ECG- and respiratory gated 3D balanced steady state free precession (bSSFP) sequence using the CLAWS algorithm (3D-bSSFP-CLAWS) with respect to acquisition time, image quality, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR).

METHODS: 14 patients (4 women, mean age ± SD: 52 ± 18) with known or suspected thoracic aortic disease were imaged on a 1.5T scanner with both sequences. Two readers scored image quality of predefined levels of the thoracic aorta. Acquisition time, SNR and CNR were calculated for each examination.

RESULTS: Image quality achieved with the 3D-bSSFP-CLAWS was scored significantly better than with the CE-3D-MRA for the aortic annulus (P = 0.003), the sinuses of Valsalva (P = 0.001), the proximal coronary arteries (P = 0.001) and the sinotubular junction (P = 0.001). Effective acquisition time for the 3D-bSSFP-CLAWS and corrected acquisition time (corrected for imaging parameters) was significantly longer compared to the CE-3D-MRA (P = 0.004 and P = 0.028). SNR and CNR were significantly higher for the CE-3D-MRA (P = 0.007 and P = 0.001).

CONCLUSIONS: Providing the highest scan efficiency for a given breathing pattern, image quality for the proximal ascending aorta achieved with the 3D-bSSFP-CLAWS is significantly superior in contrast to the CE-3D-MRA.