Multislice CT Virtual Intravascular Endoscopy for Assessing Pulmonary Embolisms: a Pictorial Review

Multislice CT has been widely used in clinical practice for diagnosing cardiovascular disease due to its reduced invasiveness and its high spatial and temporal resolution. As a reliable alternative to conventional pulmonary angiography, multislice CT angiography has been recognized as the first line technique for detecting and diagnosing pulmonary embolism. A pulmonary embolism located in the main pulmonary artery, as well as being located in the segmental branches, can be accurately detected with multislice CT imaging, and especially with the use of 16- and 64-slice CT scanners. Visualization of pulmonary embolisms has traditionally been limited to 2D, multiplanar reformation and the 3D external surface visualizations. In this pictorial review, we present our experience of using 3D virtual intravascular endoscopy to characterize and evaluate the intraluminal appearance of pulmonary embolisms in a group of patients who were suspected of having pulmonary embolism and who were undergoing multislice CT angiography. We expect that the research findings from this study will provide insight into the extent of disease and the luminal changes to the pulmonary arteries that are due to the presence of thrombus, and so monitoring of the progress of disease and predicting the treatment outcome can well be achieved

CT pulmonary angiography: an over-utilized imaging modality in hospitalized patients with suspected pulmonary embolism

Aims: To determine if computed tomographic pulmonary angiography (CTPA) was overemployed in the evaluation of hospitalized patients with suspected acute pulmonary embolism (PE). Methods: Data were gathered retrospectively on hospitalized patients (n=185) who had CTPA for suspected PE between June and August 2009 at our institution. Results: CTPA was done in 185 hospitalized patients to diagnose acute PE based on clinical suspicion. Of these, 30 (16.2%) patients were tested positive for acute PE on CTPA. The Well's pretest probability for PE was low, moderate, and high in 77 (41.6%), 83 (44.9%), and 25 (13.5%) patients, respectively. Out of the 30 PE-positive patients, pretest probability was low in 2 (6.6%), moderate in 20 (66.7%), and high in 8 (26.6%) (p=0.003). Modified Well's criteria applied to all patients in our study revealed 113 (61%) with low and 72 (39%) with high clinical pretest probability. When modified Well's criteria was applied to 30 PE-positive patients, 10 (33.3%) and 20 (66.6%) were found to have low and high pretest probability, respectively (p=0.006). D-dimer assay was done in 30 (16.2%) of the inpatients with suspected PE and all of them were found to have elevated levels. A lower extremity duplex ultrasound confirmed deep venous thrombosis in 17 (9.1%) of the patients with suspected PE, at least 1 week prior to having CTPA. Conclusion: Understanding the recommended guidelines, evidence-based literature, and current concepts in evaluation of patients with suspected acute PE will reduce unnecessary CTPA examinations