Rationale and Objectives. The authors performed this study to determine if
there were differences in vascular caliber measured on angiograms obtained
with the injection protocol used for spiral computed tomography (CT) versus
that used for pulmonary angiography.
Materials and Methods. The authors studied seven juvenile anesthetized pigs
by using a prospective repeated measures experimental design. All pigs rec
eived injections of nonionic contrast material via catheters in the brachia
l vein, superior vena cava, main pulmonary artery, and left pulmonary arter
y. Weight-adjusted injection rates and volumes ranged from 0.05 mL/kg/sec (
3.5 mL/sec, spiral CT protocol) to 0.56 mL/kg/sec (40 mL/sec, pulmonary ang
iography protocol). Heart rate and pulmonary artery and systemic artery pre
ssures were recorded. During each injection, identically positioned pulmona
ry angiograms were obtained at full inspiration. Vessel diameters were meas
ured at identical locations after each injection by two observers. The rela
tionship between vessel diameter and hemodynamic parameters and injection s
ite and rate was assessed with analysis of variance.
Results. At suspended full inspiration, no statistically significant differ
ence (P > .05) in vessel diameter or hemodynamic parameters was found betwe
en the different injection sites or rates. There was no difference in vascu
lar caliber between systole and diastole.
Conclusion. The improved detection of subsegmental pulmonary emboli at pulm
onary angiography compared with contrast material-enhanced spiral CT is not
due to differences in vascular distention.