CONTRAST-ENHANCED THIN SLICE ULTRAFAST COMPUTED-TOMOGRAPHY FOR THE DETECTION OF SMALL PULMONARY EMBOLI - STUDIES USING AUTOLOGOUS EMBOLI INTHE PIG

RATIONALE AND OBJECTIVES. Ultrafast computed tomography (UFCT) has pro ven useful, but is of limited practical application in the diagnosis o f central pulmonary embolism; however, its ability to detect more peri pheral emboli has not been established. In this study, the use of cont rast-enhanced UFCT images for the detection of autologous peripheral p ulmonary emboli in the pig is evaluated.METHODS. A Single autologous e mbolus measuring 0.7 x 1.5 cm was introduced into the superior vena ca va of eight pigs. Contiguous, 3-mm axial UFCT images from the lung ape x to the base were obtained before and after the introduction of the e mbolus. After scanning, the pigs were killed, and the thorax was remov ed intact and was frozen in a dry ice-alcohol mixture. Later, the thor ax was sliced at 10-mm thicknesses, and the locations of the emboli we re determined by a pulmonary pathologist blinded to the imaging result s. Concomitantly, the locations of the emboli were determined by conse nsus of three chest radiologists blinded to the autopsy results. RESUL TS. In 6 of 8 animals with emboli, the embolus location correlated exa ctly with the autopsy findings. In one, the embolus was on the same si de, but 1.6 cm further distal. In the other, a marking suture was iden tified, but no clot was identified on the pathologic or UFCT examinati on. In the eight animals scanned before the introduction of the embolu s, no embolus was found. Interobserver agreement was 100%. CONCLUSIONS . Ultrafast computed tomography has the potential to detect autologous emboli in second- to fourth-division pulmonary vessels. Further studi es are needed to determine if in vivo emboli can be similarly visualiz ed.