Assessment of chronic aortic dissection: contribution of different ECG-gated breath-hold MRI techniques.

OBJECTIVE: Our objective was to evaluate the impact of different rapid MRI techniques for the assessment and follow-up of chronic aortic dissections.
MATERIALS AND METHODS: Fifty-three patients (41 postoperative Stanford type A, 12 type B dissections) were scanned at 1.5 T during a 3-year period. The study reviewed ECG-gated breath-hold black blood sequences and 3D contrast-enhanced MR angiography of the thoracic aorta supplemented by segmented cine and phase-contrast imaging as well as abdominal contrast-enhanced MR angiography. A retrospective separate analysis of black blood acquisitions and contrast-enhanced MR angiograms from a total of 72 examinations was performed by two radiologists to evaluate detection of intimal flaps and assess image quality.
RESULTS: Sensitivity and specificity of black blood sequences compared with those of contrast-enhanced MR angiography in detecting intimal flaps were 87% and 94% for the thoracic aorta, and 54% and 97% for the supraaortic branches, respectively. Contrast-enhanced MR angiography was subjectively rated as superior to black blood techniques for visualizing intimal flaps and yielded better overall image quality (p < 0.001). Aortic valve competence can be assessed on segmented cine techniques. Phase-contrast sequences enabled the quantification of regurgitant flow across the aortic valve and the analysis of flow patterns in the true and false channels.
CONCLUSION: Contrast-enhanced MR angiography is superior to black blood MRI in detecting the presence or absence of intimal flaps and is particularly useful in assessing supraaortic branch vessel involvement. Cine and phase-contrast techniques should be included in the imaging follow-up to diagnose possible complications of chronic aortic dissections.