Advances in CT pulmonary angiography for pulmonary embolism

In this thesis the possibilities of improving the clinical workflow and risk assessment of patients with the suspicion of a pulmonary embolism in general, and in specific populations and circumstances have been explored. With computed tomography pulmonary angiography (CTPA) not only the presence of pulmonary emboli can be diagnosed, but also risk estimation can be established.
Part I of this thesis describes the development of a new diagnostic management strategy for patients with the suspicion of a pulmonary embolism, by combining three Wells criteria (haemoptysis, signs of deep vein thrombosis and ‘pulmonary embolism most likely’) with the D-dimer test result. Use of this YEARS algorithm resulted in an absolute 14% decrease of CTPA examinations in all ages and across several subgroups.
In Part II we explored in patients with proven pulmonary embolism the additional value of CTPA on risk assessment and prognosis. It appeared that only an enlarged pulmonary trunk diameter was associated with an increased risk of mortality. Additionally, concomitant disease on the baseline CTPA impacts mortality in a severity dependent manner. Worse outcomes are observed in patients who are overweight or underweight.
In Part III, the interaction between COVID-19 and pulmonary embolism and deep vein thrombosis is discussed. The risk for thrombotic disease in COVID-19 is very high, particularly in ICU patients. ICU patients also show severely diminished perfusion on dual energy CTPA, consistent with diffuse pulmonary microcirculatory dysfunction, which could explain the occurrence of severe and persistent respiratory failure.