Multi-Detector Computed Tomographic Pulmonary Angiography in The Evaluation of Acute Pulmonary Embolism

Abstract

Pulmonary embolism is a common condition with remarkable morbidity and mortality. Rapid and accurate diagnosis is very important since the mortality and complications of untreated pulmonary embolism is very high. As signs and symptoms are not specific, diagnosis largely depends on imaging testings. Since the introduction of multi-detector computed tomography technology with high spatial and temporal resolution, CT-pulmonary angiography (CTPA) has become the imaging method of choice for imaging lung vessels when pulmonary embolism is suspected.The study aims to estimate the prevalence of acute pulmonary embolism in patients with acute chest symptoms and high clinical suspicion. The study also intends to assess the site and degree of pulmonary arterial obstruction using Quandli scoring index and to investigate any relationship between pulmonary artery obstruction index, CT signs and features of right ventricular dysfunction in patients detected to have pulmonary embolism by CT. The study is also used to compare the findings of CT pulmonary angiography with plasma D-dimer assay.This study was a cross-sectional study conducted on 100 subjects with clinically suspicious of pulmonary embolism who were referred to Department of Radiodiagnosis, Govt Medical college, Thrissur forundergoing CTPA contrast during 2021 – 2022 and were selected based on predefined inclusion and exclusion criteria.  CTPA were interpreted to assess the presence of thrombus and other significant findings. The vascular obstruction index was quantified using the Qanadli scoring index and CT signs were used to assess right ventricular dysfunction. The data was analysed using IBM SPSS 25.0 software and the results were interpreted.CTPA reported 33% subjects were positive for pulmonary embolism. Majority of the patients belonged to group ≥60 (54%) with equal male to female ratio.  Of the CTPA performed, 67% showed no signs of occlusion and hence graded as score 0, while 30% showed partial occlusion,graded as score 1 and 3% showed complete occlusion and graded as 2. Based on the quantification using Qanadli scoring index, a cut off value of 33% was taken and analysed. Thus, a total of 33 PE positive patients were divided into two groups; one group of PAOI ≤ 33% (n=20, 60.6%) and another group of PAOI 33%-100% (n=13, 39.3%). About 69.6% patients had history of deep venous thrombosis and 57.5% patients had history of post covid infection. Cough and dyspnoea were the commonest symptoms. D-dimer was positive in 87.9% patients with pulmonary embolism. In PAOI > 33-100% group, the proportion of cases with right ventricular diameter (RvD)/ left ventricular diameter (LvD) >1 was 86.6%, pulmonary artery diameter (PaD)/ aortic diameter (AoD) >1 was 86.6% and pulmonary trunk diameter (PtD) >29 mm was 86.6% respectively. Most commonly involved were right lower lobes (75.7%) and segmental arteries (42.4%) of lung. Risk stratification of patients with PE is important because optimal management, monitoring and therapeutic strategies depend on the prognostication. Accordingly, PAOI based on Qanadli score could be used to grade the severity of pulmonary embolism and to monitor patients requiring an objective repeat evaluation.