Hypointense boundary layer between slow flow and mural thrombus on spin-echo MR.
To evaluate the ability of spin-echo MRI to differentiate between slow flow and mural thrombus in aortic diseases, we reviewed the spin-echo MRI of 10 patients with intraaortic thrombus that had been documented by CT in 8 patients and aortography in 2 patients. Six patients had aortic aneurysms with mural thrombi, and four had aortic dissections with adherent mural thrombi within the false lumen. Five of seven gated oblique sagittal or coronal T1-weighted studies demonstrated hyperintense slow flow signal within the residual lumen. This hyperintense slow flow signal was accompanied by a parallel hypointense rim due to a boundary layer dephasing phenomenon. Eight axial T2-weighted MR studies demonstrated a hypointense zone due to fresh clot at the edge of a mural thrombus on even-echo images consistently. The hypointense boundary layer between slow flow and mural thrombus on either gated T1-weighted MRI or second-echo T2-weighted MRI not only predicted the presence of flow within the residual lumen but also clearly separated the area of slow flow from that of mural thrombus in 9 of 10 patients. Proper interpretation of spin-echo images may obviate the need for phase display imaging or gradient-echo imaging in differentiating between slow flow and mural thrombus.
Chung
J W
JW
Department of Radiology, Seoul National University, College of Medicine, Korea.
Park
J H
JH
Han
J K
JK
Kim
H C
HC
Han
M C
MC
D000328:Adult; D000368:Aged; D000784:Aortic Dissection / Q000473:pathology / Q000503:physiopathology; D001011:Aorta / Q000473:pathology / Q000503:physiopathology; D001014:Aortic Aneurysm / Q000473:pathology / Q000503:physiopathology*; D001783:Blood Flow Velocity; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow / Q000502:physiology; D012189:Retrospective Studies; D013927:Thrombosis / Q000473:pathology / Q000503:physiopathology*