Background: Pulmonary Embolism PE is a potentially fatal disorder and the third most common acute cardiovascular disease, after myocardial infarction and stroke. In current clinical practice Lung Ventilation / Perfusion Scintigraphy is mainly used to exclude PE andComputed Tomography Pulmonary Angiography CTPA has now been widely accepted as the standard test for the diagnosis of acute pulmonary emboli. Aim of work: to compare the performance of dual energy
computed tomography lung perfusion and ventilation/perfusion scintigraphy in the detection of pulmonary embolism.
Patients and Methods: Twenty-six patients with suspected acute pulmonary thromboembolism underwent both DECT and SPECT V/Q scanning. Nine of these patients were females and 17 were males. Average age of the patients was 55.2 years. The diagnostic value of DECT lung perfusion imaging was assessed regarding V/Q SPECT as standard of reference. Diagnostic accuracy was calculated per patient and per segment using standard contingency tables. Chi-square test
and Receiver operating characteristic curve were to assess sensitivity, specificity, positive predictive value, negative predictive value and accuracy taking SPECT as a gold standard. Results: acute PE was diagnosed in 19 patients based on DECT findings and in 16 patients based on nuclear medicine findings. Concordant positive diagnoses were made in 16 patients. Two patients had segmental and subsegmental perfusion defect in both imaging modalities. Due to a correlative ventilation defect (matched V/Q SPECT), this finding was rated as being consistent with prior PE in nuclear medicine imaging. However, CTPA findings suggested acute PE due to an intraluminal filling defect in the supplying segmental
artery that showed a typical configuration of a recently developed embolus.One patient result was false negative with homogeneous perfusion in both DE iodine mapping and SPECT, there was nonocclusive embolus at the segmental level outlined by contrast material. Seven cases showed negative diagnoses, i.e. no evidence of PE. Sensitivity/specificity for the detection of perfusion defects were thus 82.9% and 100% by DECT iodine perfusion mapping per segment and
combined DE-CTPA had a sensitivity/specificity of 100%/100% for detection of acute PE per patient. Conclusion: DECT is the test of choice for the evaluation of suspected PE due to its availability, speed, high accuracy, and ability to identify alternative diagnoses.