J Korean Radiol Soc.
1993 Jun;29(3):395-401.
Slow flow and mural thrombus in aortic diseases: Spin-echo MR findings and their differentiation
Abstract
- In order to evaluate the ability of spin-echo MR imaging to differentiate slow flow from mural thrombus in aortic diseases, we reviewed the spin-echo MR images of 13 patients with intraaortic thrombus documented by CT (N=11) or aortography (N=2). Six patients had aortic aneurysms and seven had aortic dissection. Intraaortic mural thrombi were accompanied by flow-related intraluminal signal of various patterns and extents in all 13 patients. On 10 gated MR studies, slow flow regions showed even-echo rephasing phenomenon (N=8), interslice variation of signal intensities of the intraluminal signal (N=7) and flow-related ghost artifact (N=2). However, these MR flow phenomena were obscured on two of three non-gated studies. Seven of 13 intraaortic thrombi remained hyperintense on T2-weighted second-echo images. In these circumstances, a hypointense boundary layer between slow flow and mural thrombus, which was caused by either 'boundary layer dephasing phenomenon' of slow flow or 'paramagnetic T2 shortening' of fresh clot at the edge of mural thrombus, was useful in discriminating the area of slow flow from that of mural thrombus. Proper interpretation of spin-echo MR images may obviate the need for phase display imaging or gradientecho imaging in differentiating slow flow and mural thrombus.