Simultaneous 3D aortic lumen and vessel wall imaging at 0.55 T at either systole or diastole.

PURPOSE

To evaluate the feasibility of a novel, non-contrast enhanced, 3D, simultaneous bright-blood, and black-blood sequence (iT2prep-BOOST) for aortic imaging at 0.55 T at either systole or diastole.

METHODS

Simultaneous contrast-free 3D aortic lumen and vessel wall imaging at 0.55 T is achieved using the recently introduced iT2prep-BOOST framework that interleaves the acquisition of two bright blood images (with inversion recovery T preparation [T2prep-IR] and no preparation). To enable either systolic or diastolic aortic imaging, three T preparation pulses were investigated-an adiabatic RF pulse and two Malcolm-Levitt (MLEV) pulses (MLEV4 and MLEV8)-to improve image quality in regions with high flow and susceptibility. The proposed approach was evaluated in phantom, 10 healthy subjects and 3 patients with suspected cardiovascular disease. Bright- and black-blood images resulting from the three different T preparation pulses were compared both qualitatively and quantitatively, using a 4-point Likert scale for vessel sharpness and presence of blood artifacts. Additionally, the contrast ratio between the lumen and myocardium was computed. Aortic measurements, including the aortic annulus area at systole and diastole, cusp-commissure measurement at the aortic root level during diastole, and aortic diameter at the ascending aortic level during diastole were also performed.

RESULTS

Excellent or good image quality scores were obtained for both bright- and black-blood images with iT2prep-BOOST at 0.55 T with all three preparation pulses. The use of MLEV8 T preparation scheme improves systolic image quality, reducing the presence of artifacts with a significant difference (p < 0.05) at the mid descending aorta level. This scheme also increases the contrast ratio between aortic lumen and myocardium, compared to the previously used adiabatic RF T preparation. The aortic root diameter and area were consistent with values reported in the literature for healthy subjects at 1.5 T.

CONCLUSION

The feasibility of a novel, non-contrast-enhanced, 3D aortic imaging framework for simultaneous bright-blood and black-blood imaging was demonstrated at 0.55 T for either systole or diastole, with a scan time of 7 min. Good image quality scores and aortic measurements in agreement with literature values at 1.5 T were achieved with the MLEV8 T preparation. Studies in a larger cohort of healthy subjects and patients with aortopathies are warranted.