Figure 20. Aortic dissection (DeBakey type III). Dynamic subtraction MR angiogram obtained with three separate injections of gadopentetate dimeglumine shows the true lumen (solid arrows) compressed by the patent pseudolumen (solid arrowheads). Note the thrombus in the pseudolumen (open arrows). The left renal artery (open arrowhead) branches off from the true lumen.