Evaluation of acute aortic dissection by cine-MRI.
We investigated operative indication of acute aortic dissection by analyzing the movement of the intimal flap using cine-MRI.


METHODS
Ten consecutive cases of acute aortic dissection diagnosed between December 1997 and September 1998 participated in this study. Six of these patients had in Stanford type A and four Stanford type B aortic dissection. The diagnosis of aortic dissection was based on demonstration of two aortic channels with each cardiac cycle. After obtaining SE(spin-echo) images, gradient echo sequences (FFE) were obtained such that the false lumen was maximally imaged and the intimal flap was depicted perpendicularly. During one RR-interval of ECG, 12 to 16 measurements were recorded and combined in a cineloop mode. We defined the intimal flap, the site of the entry and thrombosis in the false lumen, and evaluated the movement of the intimal flap as the flap movement index (FMI). Maximum and minimum aortic diameters (ADmax, ADmin), as well as maximum and minimum false lumen diameters (FDmax, FDmin) were measured. FMI was defined as[(FDmax/ADmax) - (FDmin/ADmin)]/(FDmin/ADmin) x 100(%).


RESULTS
Total thrombosis was noted in four cases, partial thrombosis in 3, and in the remaining 3 no thrombosis of the false lumen was noted. The FMI ranged between 4% and 87% (mean 26.3 +/- 8.6%). Among the 4 cases with the large FMI of greater than 30%, 3 underwent emergency surgery and were confirmed to have no thrombosis in the false lumen. The fourth case, who had partial thrombosis, underwent medical therapy, but since complete thrombosis in the false lumen never did occur in this case, surgery became absolutely necessary. The other 6 cases with a FMI of less than 30% showed a tendency toward gradual reduction of the false lumen.


CONCLUSIONS
FMI is a potentially useful parameter in cases with acute aortic dissection to determine whether or not emergency surgery is indicated.
Minami
H
H
Department of Surgery, Kobe University School of Medicine.
Sugimoto
T
T
Okada
M
M
D000208:Acute Disease; D000368:Aged; D000784:Aortic Dissection / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D001014:Aortic Aneurysm / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D004632:Emergency Medical Services; D005260:Female; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D013927:Thrombosis / Q000150:complications / Q000175:diagnosis; D017539:Tunica Intima / Q000503:physiopathology