Evaluating the Performance of Unenhanced Computed Tomography in the Diagnosis of Pulmonary Embolism

Background: Computed tomography pulmonary angiography (CTPA) as the gold-standard examination in the detection of pulmonary embolism (PE) is contraindicated or unavailable in certain cases. The current study aimed to assess the accuracy of unenhanced CT in the diagnosis of PE. Methods: This cohort study was conducted between October 2020 and March 2021 in Birjand, Iran, on 195 participants with clinical suspicion of PE examined with multidetector computed tomography (MDCT) scanning and CTPA. The patients were categorized into 2 groups based on the diagnosis PE in CTPA results. Imaging variables in unenhanced CT scans, including hyper/hypodense intraluminal signs, pulmonary trunk enlargements, peripheral wedge-shaped opacities, and pleural effusions, were independently reviewed by 2 radiologists and then compared between the groups. Results: There were 82 men (42.1%) and 113 women (57.9%) at a mean age ± standard deviation of 56.00±0.24 years. Based on CTPA results, PE was diagnosed in 24.1% of the study population (47/195). However, only 20 cases (42.5%) were detected by MDCT: 17 cases (85.0%) with central PE and 3 cases (15.0%) with peripheral PE. Concerning the intraluminal clot density, 12 patients (60.0%) had hyperdense signs, 3 (15.0%) had hypodense signs, and 5 (25.0%) had mixed hyper/hypodense signs. There was a significant difference between central PE and peripheral PE detected by MDCT. Intraluminal signs had the highest specificity and sensitivity (98.6% and 42.5%, area under the curve =0.734). Conclusion: Unenhanced MDCT has a remarkable performance in detecting PE, specifically central clots, and can, therefore, be considered an alternative modality when CTPA is not available or indicated.