Robert Tung is a Cardiologist, Johannes Heyns is a Radiologist, and Lynne Dryer is a Radiology and Cardiology Nurse Practitioner; all at the US Department of Veterans Affairs Eastern Kansas Healthcare System in Topeka. Correspondence: Robert Tung (robert.tung@va.gov)
Author disclosures The authors report no actual or potential conflicts of interest with regard to this article.
Disclaimer The opinions expressed herein are those of the authors and do not necessarily reflect those of Federal Practitioner, Frontline Medical Communications Inc., the US Government, or any of its agencies.
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 nondiagnostic 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.
Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a well-established technique for the evaluation of coronary artery disease (CAD).1 To improve image quality, low-resolution computed tomography (CT) is used commonly for anatomical correct and artifact attenuation during SPECT MPI.2 The low resolution, unenhanced CT images are considered low quality and are, therefore, labeled by the manufacturer as nondiagnostic. The CT portion of the MPI in many centers is used only for image fusion and attenuation correction, and these images are not routinely reviewed or reported by cardiologists.
Incidental findings by these low-resolution CT were frequent. However, clinically significant findings, including lung cancer, although relatively infrequent, were serious enough for major clinical management.3-5 Currently, there are no consensus recommendations for reviewing low-resolution CT images or the interpretation of such incidental findings during cardiac MPI.6 Clinically, low-dose CT were used for early detection and screening of lung cancer and were associated with reduced lung-cancer and any cause mortality in National Lung Screening Trial (NLST).7,8 Therefore, low-dose CT is recommended for lung cancer screening of high-risk patients by the US Preventive Service Task Force (USPSTF).9 In the veteran population, current and past smoking history are more common when compared with the general population; therefore, veterans are potentially at increased risk of lung cancer.10 In this study, we did not intend to use low-resolution CT for lung cancer screening or detection but rather to identify and report incidental findings of pulmonary/hilar malignancy detected during cardiac MPI.
