17 Furthermore, pulmonary CTA only provides anatomic imaging of pulmonary vessels and does not provide a direct assessment of the impact of PE on lung parenchymal perfusion. 8 In addition, the success rate and diagnostic accuracy of anatomic imaging with pulmonary CTA drop as the vessel size decreases to the subsegmental level.

However, these radiological features are not specific to pulmonary emboli and can also result from a number of other pathological factors (e.g., the presence of a mucus plug or perivascular edema) and anatomical factors (e.g., vascular bifurcations and misidentification of pulmonary veins), all of which can generate PE-mimicking filling defects on pulmonary CTA images. Pulmonary emboli often manifest as partial or complete intraluminal pulmonary vessel filling defects on pulmonary CTA images and each defect usually presents a sharp interface with the iodinated contrast. 6- 17 Pulmonary CTA can also be used for the evaluation of other pulmonary thromboembolic diseases, such as chronic PE and chronic thromboembolic pulmonary hypertension (CTEPH). 5 Currently, pulmonary CT angiography (CTA) is the preferred imaging modality for evaluating patients with clinically suspected acute PE. 5 Pulmonary embolism (PE) is a venous thromboembolic event associated with high morbidity and mortality.

Venous thromboembolism is a major global health concern and an economic burden with approximately 10 million cases occurring each year and a high lifetime risk of 8% after 45 years of age. ConclusionĮffective atomic number–based quantitative PBV maps provide the needed sensitive and specific biomarker to quantify pulmonary perfusion defects. Additionally, when there are no perfusion defects present in the derived PBV maps, no pulmonary emboli were diagnosed by an experienced thoracic radiologist. ResultsĪmong patients with pulmonary emboli, the proposed maps clearly show the perfusion defects while the PBV iodine maps do not. Perfusion maps were generated for four human subjects to demonstrate the differences between conventional iodine material image-based PBV (PBV iodine) derived from two-material decompositions and the proposed method.

Namely, quantitative is determined by Z eff images instead of the iodine basis images. The quantitative relationship between the perfusion blood volume (PBV) in pulmonary parenchyma and the effective atomic number ( Z eff) spatial distribution was studied to show that the desired quantitative PBV maps are determined by the spatial maps of Z eff as, where a, b, and β are three constants. (i) To demonstrate the limitations of iodine material images in pulmonary perfusion defect quantification and (ii) to develop and validate a new quantitative biomarker using effective atomic numbers derived from DECT images. However, iodine material images do not provide the needed absolute quantification of the pulmonary blood pool, as materials with effective atomic numbers ( Z eff) different from those of basis materials may also contribute to iodine material images, thus confounding the quantification of perfusion defects. Iodine material images (aka iodine basis images) generated from dual energy computed tomography (DECT) have been used to assess potential perfusion defects in the pulmonary parenchyma.

Li atomic number