DIAGNOSIS OF CENTRAL PULMONARY-EMBOLISM WITH HELICAL CT - ROLE OF 2-DIMENSIONAL MULTIPLANAR REFORMATIONS

OBJECTIVE. The purpose of this study was to evaluate the role of multi planar two-dimensional (2D) reformations in the diagnosis of central p ulmonary embolism with helical CT. SUBJECTS AND METHODS. Thirty-five p atients with suspected pulmonary embolism underwent contrast-enhanced helical CT of the pulmonary arterial tree. Two sets of images were ana lyzed: overlapped transverse sections and 2D reformatted images of 10 obliquely oriented arteries (interlobar pulmonary artery, A2, A4+5, A6 , and A10 [A = artery]) selected on three-dimensional shaded surface d isplays of each pulmonary arterial tree. RESULTS. Among the 20 patient s with unequivocal central pulmonary emboli on transverse sections (gr oup 1), 2D reformations enabled a more precise analysis of the extent of thromboembolic disease in 13 cases. These patients underwent no fur ther diagnostic procedure. In six patients (group 2), transverse secti ons alone excluded central pulmonary embolism with angiographic (n = 2 ) or scintigraphic (n = 4) confirmation. No additional information was provided with the 20 reformations. in nine patients with an uncertain diagnosis of pulmonary embolism on transverse sections (group 3), 2D reformations enabled us to exclude central emboli in all the cases, wi th angiographic (n = 4) or scintigraphic (n = 5) confirmation. In grou ps 1 and 3, 2D reformations provided adequate visualization of oblique ly oriented arteries (n = 30) and enabled assessment (n = 2) or exclus ion (n = 28) of endovascular changes, a clear distinction between endo luminal and perivascular abnormalities (n = 7), or a precise evaluatio n of extensive mural thrombi (n = 6). CONCLUSION. Our results show tha t 2D reformations enable confident exclusion of pulmonary embolism on inconclusive helical CT examinations and improve analysis of the exten t of thromboembolic disease.