CTPA is the primary imaging technique for the majority of patients in the investigation of suspected pulmonary embolus with ventilation and perfusion scintigraphy supporting this in appropriate patient populations. There is significant morbidity and mortality associated with pulmonary embolism and accurate diagnosis or exclusion is integral to the investigative process. This is a re-audit of an audit that has been performed since 2008 and will evaluate the usage and accuracy of imaging in the investigation of suspected pulmonary embolus at a district general hospital.

Retrospective audit of CTPA and V/Q scan reports from August to October 2016, the same time period as previous audits. CTPA reports will be assessed as positive, negative, negative with alternate diagnosis or indeterminate. V/Q reports will be assessed as positive, indeterminate, negative and whether the patient went on to have a CTPA Numbers will then be compared with previous years and the published RCR standards. The RCR audit recipe suggests a standard that CTPA should detect pulmonary emboli in between 15.4% and 37.4% of...

CTPA – 346 investigations with a 22.2% detection rate, previously 265 investigations with a detection rate of 20%, in keeping with the RCR standard. Additional diagnoses were highlighted in 42% of negative cases and of these 37% were collapse/consolidation/pleural effusions that were visible on the preCTPA radiograph V/Q – 18 investigations (10 V/Q and 8 Q only) with a 5% indeterminate rate, previously 24 investigations with a 8% indeterminate rate. The sole indeterminate examination went on to have a positive CTPA result.

The institution is performing more CTPA examinations than the comparative period of the previous audit but has maintained a consistent rate of positive diagnosis, suggesting that existing referral pathways and skill mix of reporters are adequate. Further audit cycles could focus on the referral pathway and clinical risk stratification/use of screening tests such as d-dimer assay.

Dr Adam F Hughes FRCR, Specialty Registrar, Nottingham Training Scheme, UK Dr Susan Geary FRCR, Consultant Radiologist, King's Mill Hopsital, Mansfield, UK

https://www.rcr.ac.uk/audit/appropriateness-usage-computed-tomography-pulmonary-angiography-ctpa-investigation-suspected Mos IC, Klok FA, Kroft LJ, DE Roos, Dekkers OM and Huisman MV. Safety of ruling out acute pulmonary embolism by normal computed tomography pulmonary angiography in patients with an indication for computed tomography: systematic review and meta-analysis. J Thromb Haemost. 2009 Sep;7(9):1491-8. Epub 2009 Jun 22.