Computed tomographic pulmonary angiography: utility in acute pulmonary embolism in providing additional information and making alternative clinical diagnosis.

Objective: To evaluate the role of computed tomographic (CT) pulmonary angiography (CT-PA) in detecting additional information that may help in making an alternative clinical diagnosis in patients referred to CT for a suspected acute pulmonary embolism (PE).

Materials And Methods: 50 patients (34 males, 16 females) in the age group of 18-72 years (mean 42.3 years), having high clinical suspicion of PE, underwent CTPA over a 2 year period. Chest x-ray, arterial blood gas (ABG) analysis, echocardiography were done in all patients. All patients underwent at least one other imaging examination besides CTPA: ventilation perfusion scan, Doppler ultrasound or compression ultrasound (for DVT). All patients were followed for 3 months after completion of the diagnostic work up at baseline. The final diagnosis was achieved by a combination of clinical, imaging, and laboratory analysis, after adequate imaging, laboratory tests, and follow up.

Result: CTPA helped correctly identify 29 of 30 patients with PE. In the remaining 20 patients (with no evidence of PE), CT-PA provided additional information (that suggested or confirmed alternate clinical diagnosis) in 15 patients (75%): pleural effusion (n=8), mediastinal or hilar lymphadenopathy (6), pneumonia/airspace consolidation (5), atelectasis/collapse (2), aspergilloma (1), malignancy (1), and others (2).

Conclusion: CT-PA is highly specific and sensitive for diagnosis of PE. In addition, in a majority of patients who do not have PE, it also provides important ancillary additional information and helps in making an alternative clinical diagnosis.