UC Irvine

Various lung disorders can lead to respiratory failure that causes significant morbidity and mortality, such as pulmonary thromboembolic disease, obstructive airway disease, and lung cancer. At present, computed tomography (CT) imaging of the chest plays a vital role in identifying distinct patterns between pulmonary diseases with varied clinical presentations. Pulmonary embolism (PE) is the third most common cardiovascular disease after cardiac infarction and stroke. While CT pulmonary angiography (CTPA) has become the first-choice imaging technique for including and excluding PE, it can only provide the morphological severity of PE without the physiological assessment regarding the pulmonary blood flow circulation. Hence, it is essential to understand physiological and pathophysiological mechanisms of pulmonary disorders via the assessment of pulmonary perfusion. Unfortunately, existing contrast-enhanced dynamic CT pulmonary perfusion techniques are limited by their unacceptable high radiation dose, systematic estimation bias, and limited scan coverage in the quantification of absolute perfusion for the entire lung, precluding their widespread clinical use. As such, there is a clinical necessity to develop an accurate, low-dose, whole-lung dynamic CT perfusion technique at a low radiation dose in conjunction with the CTPA image. Such a technique should be capable of providing a comprehensive assessment with both morphological and physiological information and potentially improve the diagnosis and management of pulmonary diseases at early stages.This dissertation tackles all these limitations of existing dynamic CT perfusion techniques. An accurate, low-dose, quantitative pulmonary CT-based technique incorporating CT pulmonary angiography and CT perfusion acquisition was developed, validated, and equipped for clinical translation. Such a comprehensive CT technique can accurately measure the absolute whole-lung perfusion on a voxel-by-voxel basis and evaluate regional perfusions on a lobar basis, while simultaneously providing the CTPA within a single contrast injection at a reduced effective radiation dose. Therefore, the morphological and physiological assessment of pulmonary disease is feasible using a single low-dose CT examination, making the CT-based evaluations of pulmonary diseases more reliable, accessible, and impactful to patients in need.