Introduction and objectives CT pulmonary angiography (CTPA) is recommended as the investigation of choice for suspected pulmonary embolism (PE). Even in appropriately risk-assessed groups, CTPA often proves negative for PE, but additional diagnostic information is still provided by technically adequate scans. We reviewed our CTPAs to assess technical quality and final diagnosis.

Methods Retrospective review of CTPAs performed in 2013 in a 588 bed district general hospital. All patients selected were considered either intermediate or high probability for PE based on Wells PE clinical risk scoring. Only imaging performed on patients presenting as acute admissions was reviewed. Patients under the age of 16 were excluded, but no upper age limit was applied in order to be fully representative of our patient population and clinical practice. Scans were assessed for their diagnostic and technical quality by the reporting radiologist.

Results 720 CTPAs were selected for review. Patient mean age 66.4 (range 17–103). PE was demonstrated in 135 studies (18.8%). 111 CTPAs (15%) excluded PE and were otherwise normal. 355 CTPA (49%) excluded PE but revealed an alternative diagnosis. Of these, cardiac failure (26%), emphysema (19%), pneumonia (16%), interstitial lung disease (10%), bronchiectasis (9%) and pleural disease (8%) were the most frequently reported clinically significant diagnoses. 119 CTPAs were considered technically inadequate to exclude PE based on insufficient contrast opacification, however an alternative explanatory diagnosis was seen in 76 (64%) of these. In the remaining 43 cases no diagnosis was reported, and only 2 patients had repeat CTPA performed during the same admission. Four patients from the non-diagnostic group represented within a 3 month follow up period and were subsequently proven to have PE on repeat CTPA.

Conclusions CTPA can provide an alternative diagnosis in the majority of cases even if PE is excluded. Of these, cardiac failure and emphysema were the most common diagnoses. Physicians must be vigilant for non-diagnostic scans and arrange further tests as appropriate, as in our series 4/43 patients with technically inadequate imaging on initial presentation subsequently represented with PE.