Preliminary InvestigationsPulmonary Embolism: Comparison of Gadolinium-Enhanced MR Angiography with Contrast-Enhanced Spiral CT in a Porcine Model
Section snippets
Surgical Protocol
Fifteen female juvenile pigs (Large White-Landrace cross, 34 kg ± 3 [mean ± standard deviation]) were studied in the supine position. The study was approved by the University Animal Experimentation Committee and was carried out according to the Canadian guidelines for use and care of animals. Anesthesia was induced by intramuscular injection of ketamine hydrochloride (20 mg/kg) (Ketalean; MTC Pharmaceuticals, Cambridge, Ontario, Canada). The pigs were intubated and ventilated with a tidal
Lung Cast
Eighty-six of the 89 emboli injected (97%) were detected in the lung casts. Three emboli were found lodged in the left external jugular vein during the removal of the thoracic organs, indicating incomplete injection into the pulmonary vasculature. In addition, two emboli were located in the upper lobe segmental arteries, outside the imaging area of CT. The 84 remaining emboli created 49 unique embolic sites, 12 sites with a single large embolus (5.2 mm), 18 with a single small embolus (3.8 mm),
Discussion
Our results show that there is no difference (P > .05) in sensitivity or positive predictive value between spiral CT and MR angiography for detection of PE in this porcine model. The locations of the emboli were confirmed by using a methacrylate cast of the pulmonary vasculature as an independent diagnostic standard (15). Emboli were detected at spiral CT by the presence of a cutoff of lobar or segmental vessels. With use of lung parenchymal window and level settings at MR angiography, 80% of
Acknowledgments
The authors thank Kris Gillespie and Alexandra Ranger, animal care technicians, for their invaluable help; Chandrika Vadgama and Donna Shepard for giving up so much sleep to acquire the images; Yulia d'Yachkova, MSc, for the statistical analysis; Stuart Greene for preparing the figures; and Nestor Müller, MD, PhD, and Peter Paré, MD, for their careful reading of the manuscript.
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- 1
H.O.C. supported by a fellowship from the Canadian Thoracic Society–Medical Section of the Canadian Lung Association and by Boehringer Ingelheim.
- 2
G.R.M. supported by a grant from the British Columbia Lung Association and the Medical Research Council of Canada.