Peripheral vascular tree stenoses: detection with subtracted and nonsubtracted MR angiography.
OBJECTIVE
To compare subtracted and nonsubtracted gadolinium-enhanced magnetic resonance (MR) angiography and cardiac-synchronized time-of-flight MR angiography for help in detecting pelvic-region stenoses.


METHODS
Twenty-eight patients with intermittent claudication underwent MR angiography with a 1.5-T system; two-dimensional cardiac-synchronized time-of-flight MR angiograms and three-dimensional MR angiograms (without and with gadolinium enhancement) were obtained. Subtracted images were obtained by subtracting unenhanced data from enhanced data of identical volumes, and maximum intensity projection images were constructed, which two observers independently evaluated in blinded fashion, with conventional angiographic results as the reference standard.


RESULTS
Sensitivity and specificity for grading of hemodynamically significant stenoses (> or = 50% lumen reduction) on subtracted MR angiograms were 94% and 93%, respectively. Sensitivity of subtracted images was significantly higher compared with that of time-of-flight images (P < .05) but not with that of nonsubtracted images. Contrast-to-noise ratio on subtracted images was significantly higher compared with that on nonsubtracted images (P < .05) but not with that on time-of-flight images. There was good correlation between stenosis length measurements on gadolinium-enhanced MR angiograms and those on conventional angiograms.


CONCLUSIONS
Subtracted MR angiography is superior to cardiac-synchronized time-of-flight MR angiography for imaging of iliac and upper femoral arteries and provides higher contrast-to-noise ratio, fewer artifacts, and easier image interpretability than nonsubtracted MR angiography.
Ho
K Y
KY
Department of Diagnostic Radiology, University Hospital Maastricht, The Netherlands. Kho@rdia.azm.nl
de Haan
M W
MW
Kessels
A G
AG
Kitslaar
P J
PJ
van Engelshoven
J M
JM
D000792:Angiography; D003251:Constriction, Pathologic / Q000175:diagnosis / Q000000981:diagnostic imaging; D003287:Contrast Media; D005260:Female; D005263:Femoral Artery / Q000000981:diagnostic imaging / Q000473:pathology*; D019786:Gadolinium DTPA; D006801:Humans; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000473:pathology*; D007091:Image Processing, Computer-Assisted; D007383:Intermittent Claudication / Q000175:diagnosis* / Q000000981:diagnostic imaging; D007472:Iohexol; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D016491:Peripheral Vascular Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D013382:Subtraction Technique
D003287:Contrast Media; D007472:Iohexol; D019786:Gadolinium DTPA