Elsevier

Academic Radiology

Volume 8, Issue 4, April 2001, Pages 343-350
Academic Radiology

Preliminary Investigations
Pulmonary Embolism: Comparison of Gadolinium-Enhanced MR Angiography with Contrast-Enhanced Spiral CT in a Porcine Model

https://doi.org/10.1016/S1076-6332(03)80504-4Get rights and content

Abstract

Rationale and Objectives

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.

Materials and 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.

Conclusion

MR angiography is as sensitive as CT for the detection of small PE 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.

References (36)

  • DC Diffin et al.

    Effect of anatomic distribution of pulmonary emboli on interobserver agreement in the interpretation of pulmonary angiography

    AJR Am J Roentgenol

    (1998)
  • ER Hudson et al.

    Pulmonary angiography performed with iopamidol: complications in 1,434 patients

    Radiology

    (1996)
  • LR Goodman et al.

    Detection of pulmonary embolism in patients with unresolved clinical and scintigraphic diagnosis: helical CT versus angiography

    AJR Am J Roentgenol

    (1995)
  • M Remy-Jardin et al.

    Diagnosis of pulmonary embolism with spiral CT: comparison with pulmonary angiography and scintigraphy

    Radiology

    (1996)
  • AB van Rossum et al.

    Pulmonary embolism: validation of spiral CT angiography in 149 patients

    Radiology

    (1996)
  • JR Mayo et al.

    Pulmonary embolism: prospective comparison of spiral CT with ventilation-perfusion scintigraphy

    Radiology

    (1997)
  • K Garg et al.

    Pulmonary embolism: diagnosis with spiral CT and ventilation-perfusion scanning—correlation with pulmonary angiographic results or clinical outcome

    Radiology

    (1998)
  • Cited by (19)

    • CT for thromboembolic disease

      2003, Current Problems in Diagnostic Radiology
    • CT for thromboembolic disease

      2002, Radiologic Clinics of North America
    • Chest imaging in pulmonary embolism

      2016, Venous Thromboembolism
    • Process diagnosis of pulmonary embolism

      2013, Neumologia y Cirugia de Torax(Mexico)
    View all citing articles on Scopus
    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.

    View full text