Multicentre analysis of incidental findings on low-resolution CT attenuation correction images: an extended study

To review new incidental findings detected on low-resolution CT attenuation correction (CTAC) images acquired during single-photon emission CT-CT myocardial perfusion imaging as an extension to our initial study.

CTAC images acquired as part of myocardial perfusion imaging performed using single-photon emission CT at four UK nuclear medicine centres were evaluated as part of a multicentre study. New incidental findings that were considered to be clinically significant were evaluated further. Positive-predictive value (PPV) was determined at the time of definitive diagnosis.

Out of 3485 patients, 962 (28%) patients had a positive finding on the CTAC image, of which 824 (24%) were new findings. 84 (2.4%) patients had findings that were considered clinically significant at the time of the CTAC report and which had not been previously diagnosed. However, only 10 (0.29%) of these had findings that were confirmed as clinically significant, with the potential to be detrimental to patient outcome, after follow-up and definitive diagnosis.

The overall PPV from all centres over the 2-year period was 12%. Each centre achieved what we considered to be low PPVs with no significant difference between the present and initial studies. The additional data from the combined studies show that, statistically, there is no significant difference between the PPVs from any of the centres. We conclude that routine reporting of CTAC images is not beneficial.

This study combined with the previous study offers a unique evaluation of new clinically significant incidental findings on low-resolution CT images in an attempt to determine the benefit of reporting the CTAC images.