Incidental Findings of Pulmonary and Hilar Malignancy by Low-Resolution Computed Tomography Used in Myocardial Perfusion Imaging.

Background: Low dose, low-resolution computed tomography (CT) is used for attenuation correction to improve the quality of single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Because of its low resolution, these CT images are considered non-diagnostic and are not routinely or uniformly reviewed or interpreted by a cardiologist. On the other hand, low-dose CT has been used for lung cancer screening to reduce lung cancer mortality and is recommended for annual screening of high-risk patients by the US Preventive Services Task Force.

Methods: Siemens Symbia Intevo Excel SPECT/CT scanners, used primarily for cardiac MPI, were used in the study. The study was intended to report incidental findings of pulmonary and hilar malignancy detected by these CT images during cardiac evaluation. It included 1,098 consecutive patients who had SPECT MPI from September 1, 2017 to August 31, 2018. When suspicious pulmonary nodules or abnormalities were identified, primary care providers were notified of the findings and recommendations for further evaluation.

Results: Five patients were found to have lung cancer (all male with substantial smoking history, aged 64-75 years), 1 had mantle cell lymphoma. Six of 1,098 (0.55%) patients were found to have incidental pulmonary/hilar malignancy, which is comparable to the yield (0.65%/year) of detecting lung cancer using low-dose CT for screening in The National Lung Screening Trial.

Conclusions: Routine review and report of incidental findings on low-resolution CT during cardiac MPI by physicians skilled in CT interpretation is necessary to identify incidental but clinically important findings, including malignancies.