Evaluation of Acute Aortic Dissection by Use with Gadolinium Enhanced MR Angiogra p hy: Comparison withSpin-echo MR Image

Abstract

Purpose: To compare the usefulness of Gadolinium-enhanced MR angiography(Gd-MRA) with spin-echo(SE) MRI for the evaluation of acute aortic dissection. Materials and Methods: During a recent one-year period were trospectively reviewed the results of SE MRI and Gd-MRA in 14 patients (10 males, 4 females; mean age 57 years)with acute aortic dissection. DeBakey type I was found in six patients, DeBakey type II in one, and DeBakey typeIII in seven. MR techniques were as follows. First, multislice multiphase images were obtained in axial, coronal and oblique sagittal planes using SE T1WI(TR/TE/flip angle=600/14/90; acquisition time=25min), and images of selected slices were obtained using breath-hold turbo SE T2WI(TR/TE/flip angle=800/76/160). Second, breath-holdGd-MRA imaging (3D-FISP; TR/TE/Flip angle=4.2/1.7/25; acquisition time=1min) was performed, with oblique sagittal(arch view) orientation. We compared 14 SE MRI images with nine thoracic and five abdominal Gd-MRA images, evaluating the presence and extent of intimal flap, entry and reentry tear, thrombus in false lumen (and comparison to true lumen), the involvement of major branching vessels of the aortic arch, the origin of majorabdominal branching vessels, the presence of hemothorax and hemopericardium. Results : Both SE MRI and Gd-MRA very accurately detected the extent of intimal flap, and false lumen status. For detecting the site of entry tear, and the involvement of major branching vessels at the aortic arch, Gd-MRA(n=12) was more accurate than SE MRI(n=7).When used to image 20 vessels in five patients, Gd-MRA identified with perfect accuracy the origin of majorabdominal branching vessels; SE MRI, however, demonstrated only six of 20 vessels. SE MRI, however, was muchsuperior for the identification of complications such as hemothorax(n=9) and hemopericardium(n=2); in thisrespect, Gd-MRA failed completely. Conclusion: For the evaluation of patients with acute aortic dissection, Gd-MRAprovides information regarding site of entry tear and the involvement of major branching vessels very much fasterthan SE-MRI. In such cases, Gd-MRA can therefore be used for initial investigatory imaging.