10,589 CT pulmonary angiograms: evaluating the yield of acute pulmonary embolism

To evaluate the change in the number of CT pulmonary angiograms (CTPAs) performed and the change in the yield of acute pulmonary embolism (PE) on CTPA at a busy tertiary teaching hospital from 2016 to 2019.

All CTPA examinations for both in-patients and emergency department patients performed at our busy tertiary teaching hospital between 1 January 2016 and 31 December 2019 were identified from the radiology information system. A natural language processing technique called phrase matching was employed to assign each of the examination reports a result of either positive, negative or equivocal for acute PE. This algorithm was validated on a sample of 200 reports.

The number of CTPAs performed increased 59% from 2016 to 2019. The overall yield of acute PE has remained steady averaging 15.9%, ranging from 15.0% to 17.2%.

Over 3 years, there has been a significant increase in the demand for CTPA examinations. The yield of acute PE has remained steady indicating a justified increase in demand. The yield of acute PE on CTPA within our centre is higher than the Royal College of Radiologists' suggested minimum of 15.4% which suggests the current guidelines used for the investigation of suspected acute PE within our centre are appropriate.

The guidelines and subsequent yield of acute PE on CTPA at our tertiary teaching hospital can be used as a reference standard for other similar institutes.