Pulmonary embolism: comparison of gadolinium-enhanced MR angiography with contrast-enhanced spiral CT in a porcine model.
OBJECTIVE
The purpose of this study was to compare gadolinium-enhanced magnetic resonance (MR) angiography with contrast material-enhanced computed tomography (CT) for the detection of small (4-5-mm) pulmonary emboli (PE), with a methacrylate cast of the porcine pulmonary vasculature used as the diagnostic standard.


METHODS
In 15 anesthetized juvenile pigs, colored methacrylate beads (5.2 and 3.8 mm diameter-the size of segmental and subsegmental emboli in humans) were injected via the left external jugular vein. After embolization, MR angiographic and CT images were obtained. The pigs were killed, and the pulmonary arterial tree was cast in clear methacrylate, allowing direct visualization of emboli. Three readers reviewed CT and MR angiographic images independently and in random order.


RESULTS
Forty-nine separate embolic sites were included in the statistical analysis. The mean sensitivity (and 95% confidence intervals) for CT and MR angiography, respectively, were 76% (68%-82%) and 82% (75%-88%) (P > .05); the mean positive predictive values, 92% (85%-96%) and 94% (88%-97%) (P > .05). In this porcine model, PE were usually seen as parenchymal perfusion defects (98%) with MR angiography and as occlusive emboli (100%) with CT.


CONCLUSIONS
MR angiography is as sensitive as CT for the detection of small PE in a porcine model.
Reittner
P
P
Department of Radiology, Vancouver Hospital and Health Sciences Centre, British Columbia, Canada.
Coxson
H O
HO
Nakano
Y
Y
Heyneman
L
L
Ward
S
S
King
G G
GG
Baile
E M
EM
Mayo
J R
JR
D000818:Animals; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D018810:Magnetic Resonance Angiography; D011237:Predictive Value of Tests; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000453:epidemiology; D012680:Sensitivity and Specificity; D013552:Swine; D014057:Tomography, X-Ray Computed; D014283:Triiodobenzoic Acids
D003287:Contrast Media; D014283:Triiodobenzoic Acids; D019786:Gadolinium DTPA; C054871:ioversol