PULMONARY CIRCULATION

Evaluation of the pulmonary vasculature is mainly indicated in patient s with suspected pulmonary thromboembolism. The routine procedure so f ar is ventilation-perfusion scintigraphy alone or in combination with diagnostic assessment of the legs to rule out deep venous thrombosis. The results are still not reliable for the majority of patients. In th e case of equivocal diagnosis, invasive conventional angiography is co nsidered the gold standard. With steady improvements in tomographic im aging techniques, such as computed tomography (CT) or magnetic resonan ce imaging (MRI), non-invasive alternatives to the routine diagnostic work-up are given. Helical CT and CTA techniques are already in clinic al use and estimated to sufficiently serve the demands for detection/e xclusion of pulmonary thromboembolism. The disadvantages mainly concer n peripheral disease and reconstruction artifacts. MRI and MR angiogra phy have been implemented in the diagnosis of pulmonary vascular disea se since the introduction of contrast-enhanced MRA. In breath-hold tec hniques, the entire lung vascularization can be delineated and thrombo emboli can be detected. The clinical experience in this field is limit ed, but MRI has the potential to demonstrate its superiority over CT d ue to its improved delineation of the vascular periphery and the more comprehensive three-dimensional reconstruction.