- AIM: To assess the change in practice and resulting diagnostic outcome in the radiological investigation of pulmonary embolism (PE) since the introduction of helical CTPA in a large teaching hospital. MATERIALS AND METHODS: A retrospective review was undertaken of all radiological investigations performed over a 6-year period before and after the introduction of CTPA (protocols 1 and 2, respectively) as an integral part of the imaging protocol in the investigation of clinically suspected PE. The total numbers and results of all investigations are assessed for each protocol. RESULTS: A substantial increase in both the total number of patients and the number of investigations performed for the investigation of PE since the introduction of CTPA occurred. Five hundred and twenty-six patients underwent 617 investigations in 1995-1996, and 760 patients underwent 805 investigations in 2001-2002. There was a significant decrease in the number of investigations per patient, 1.17 in 1995-1996 versus 1.06 in 2001-2002. Primary investigation showed a significant decrease in indeterminate examinations from 25.7 to 8.5% and an increase in positive results for PE from 18 to 24%. CONCLUSION: In the study population there was a significant increase in the number of patients being investigated for PE, with a decrease in both the number of non-diagnostic investigations and the total investigations per patient since the introduction of helical CTPA. This is probably due to the ready availability of a new imaging technique and physicians awareness that CTPA has significantly improved specificity, which encourages the referral of patients for investigation.