Multi-slice computed tomography in the diagnosis of pulmonary embolism--usefulness of multiplanar reformations with batch film tool in the form of a paddle view.

Pulmonary embolism (PE) is a common and still difficult clinical problem. On autopsy, PE is diagnosed in 15-25% of hospital deaths, intravitally the diagnosis is reached in only 1/3 of cases. An early diagnosis and antithrombotic treatment decreases the mortality rate from 30 to 2-10%. The aim of the study is to show diagnostic possibilities of pulmonary artery angiography using 8-row multislice spiral computed tomography (MSCTA) and to present our own experience concerning the examination protocol as well as the way of performing and evaluating multi-planar reconstructions (MPR). Since July 2002, 62 patients suspected of having PE were subjected to MSCTA with the LightSpeed Ultra tomograph (GE) using the Smart Prep technique with 8x1.25mm collimation, 0.6mm interval, iv 100-120ml of the contrast medium (4 ml/s) with scanning delay. The scanning time was 10-14s. In the patients with severe dyspnoca the 2.5mm slices were used (the required time of breathhold--5-7s). The patients suspected of having chronic PE were additionally subjected to high resolution dynamic scanning. Postprocessing included the evaluation of native scans and multiplanar reconstructions using 3.6-5.9 MIP for visualization of pulmonary artery branches and thromboembolic material. The standard reconstructions were supplemented with the batch film tool (BFT) in the form of a paddle view. In 25 cases the values of typical and widened reconstruction algorithms were compared according to the caliber and location of vessels using the 0-3 scale. The thromboembolic material in the pulmonary arteries was visualized in 35 MSCTA examinations; in 20 cases the lesions fulfilling the criteria of acute PE dominated. In 1 case the image was inconclusive. 17 examinations revealed other types of lesions, e.g. inflammatory-infiltrative or neoplastic changes, abnormal venous flow, myxoma of the left atrium, bronchiolitis obliterans. The three-planar evaluation of MPR and MPR with BFT showed that the effectiveness rates were as follows: 2.92 and 2.96 for the main arteries, 2.68 and 2.78 for lobe arteries, 2.12 and 2.35 for segmental arteries (p<0.05), 1.68 and 2.08 for subsegmental ones (p<0.05), respectively. 1. MSCTA is a valuable and quick method of visualization of central and peripheral branches of pulmonary arteries and detection of the presence and character of embolic changes. 2. The additional use of the batch film tool in a paddle view facilitates anatomical evaluation of segmental and subsegmental branches and thromboembolic material in their lumen.