Incidental CT findings from myocardial perfusion PET/CTs

Introduction New state-of-art hybrid imaging systems provide high quality CT images along with myocardial perfusion imaging (MPI), which introduces new opportunities and challenges for interpreting and referring physicians. American and European societies recommend reporting these CT scans including non MPI related incidental findings. PET MPI studies provide CT that allows examination of the chest and upper abdomen in addition to the heart and coronary vessels. Previous studies demonstrated these incidental findings may have an important impact on detection of malignancies or other abnormalities depending on the studied population. The objective of this study was to describe the prevalence of CT incidental findings during MPI PET/CT. We hypothesized that the veteran population may have a high prevalence of incidental CT findings based on their risk factor profile. Methods This IRB-approved single-center retrospective study included 2756 patients, who underwent 82-rubidium-chloride PET-CT MPI between December 2018 and July 2022. Each patient received a low dose CT of the chest and upper abdomen for attenuation correction and anatomic localization. At our institution, complete CT reports are generated by board certified nuclear medicine physicians or cardiologists with special competency in CT interpretation. Data collected by reviewing the MPI reports resided in the PACS system. Incidental CT findings were identified, and percentages of each finding were calculated. Results In addition to abnormal PET MPI findings including ischemia and/or scar, the thoracic CT demonstrated incidental findings in aorta (14%), pulmonary artery (20%), coronary arteries (94%), lung (50%), lymph nodes (3%), and breast (12%). The upper abdominal CT findings included the liver (14%), gallbladder (10%), spleen (3%), kidneys (13%), stomach (10%), and ascites (1%). Some of these findings were deemed serious which required follow up imaging. Conclusion Our study again confirms the importance of reviewing and reporting CT component of MPI studies as recommended by American and European societies. These CT images frequently, demonstrate incidental thoracic and upper abdominal findings, some of which require further workup. However, these findings can be burdensome for the referring physician and may cause patient anxiety. Hence, adequate training and experience or a multispecialty approach may be necessary to accurately interpret and provide differential diagnosis and recommendation to minimize the healthcare burden and anxiety for patients while maximizing the clinical benefits.