Lastly, time-resolved 3D MRA can often be helpful in the comprehensive evaluation of complex congenital heart disease and the various anatomic results and developmental complications of untreated or surgically corrected conditions .
The time resolved information gained with sub-second angiography often lays out such complex anatomy and physiology in exquisite detail (Fig. 11).
Fig. 11a, b. Time resolved imaging in a child with transposition of the great vessels s/p Mustard procedure. The post-operative chamber connections in this child with transposition of the great vessels following a Mustard procedure is abnormal. The Mustard procedure places an inter-atrial baffle that corrects for the ventricular inversion of a transposition by re-directing systemic venous return to the left ventricle which is connected to the pulmonary artery, and redirecting pulmonary venous return to the right ventricle which is connected to the aorta. On a dynamic coronal 2D time resolved acquisition (a, 6 select frames), contrast is noted initially filling the "left atrium" component of the baffle (LA) and right pulmonary artery (RPA). This is followed by pulmonary venous drainage of contrast into the "right atrium" (RA) and aorta (Ao). Note the diminished signal within each chamber with progression of the contrast bolus over each temporal frame. Similar but improved vascular detail can be achieved using dynamic sub-second 3D MRA (b). On an early sub-second 3D MRA (b, top row/), enhancement of the left ventricle (LV), pulmonary artery (PA) and right pulmonary artery (RPA) are seen. On the same image, persistent enhancement of the superior vena cava and left brachiocephalic vein can also be seen-this represents the trailing edge of the contrast bolus. On a slightly later image, filling of the pulmonary veins, right atrium (RA) and right ventricle (RV) are noted. On late images (b, bottom row), progression of the bolus into the thoracic aorta (Ao) and abdominal aorta is seen. Note that due to decreased flow the left pulmonary artery (arrow) is displayed after the maximum enhancement of the aorta
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