Detection of pulmonary emboli at the segmental and subsegmental level with electron-beam CT: validation in a porcine model.

Abstract

The authors evaluated the sensitivity of electron-beam computed tomography (CT) in the detection of segmental and subsegmental pulmonary artery emboli in a porcine model. Twenty-one segmental and subsegmental branch pulmonary arteries in five swine were selectively catheterized and embolized with gelatin sponge pledgets. The presence of emboli was confirmed by means of contrast material-enhanced angiography. Contrast-enhanced CT scans of the pulmonary arteries were then obtained with 3-mm collimation, 2-mm table travel between sections, and an imaging time of 100 msec per section. Contrast material was injected at a rate of 2-3 mL/sec, depending on the animal's weight, with a total dose of 60 mL for each scan. Cardiac-gated and nongated scans were obtained, but breath holding was not possible in these animals. Contrast-enhanced electron-beam CT scanning allowed correct prospective identification of 18 of 21 emboli in the segmental and subsegmental branches of the pulmonary arteries. The overall sensitivity was 86%. Cardiac gating subjectively improved image quality but did not result in greater sensitivity in the detection of emboli. The level of sensitivity was not affected by the use of breath holding. Contrast-enhanced electron-beam CT is a sensitive method for the detection of embolism in the segmental and subsegmental pulmonary arteries.