Incidental extra-cardiac findings on ¹³N-ammonia myocardial perfusion PET/CT

Background: The objective of this study was to describe the prevalence of incidental extra-cardiac findings (IECFs) on myocardial perfusion PET/CTs and the prevalence of potentially clinically relevant and clinically irrelevant IECFs, as well as detection rate of previously unknown malignancies.

Methods and results: From September 2013 until February 2016, a total of 1397 consecutive patients referred for the evaluation of possible ischemia by ¹³NH₃ PET/CT were prospectively included in a database. IECFs were categorized into three groups: potentially clinically relevant IECFs, IECFs that could potentially cause chest pain, and clinically irrelevant IECFs. Additionally, the prevalence of previously unknown malignancies was determined. In 717 (51%) of these patients, 775 IECFs were reported and 115 IECFs were categorized as potentially clinically relevant in 109 (8%) patients. A total of 145 IECFs that could potentially cause chest pain were detected in 139 (10%) patients and 515 clinically irrelevant IECFs were detected in 469 (34%) of the patients. An unknown primary malignancy was histologically proven in 19 patients (1.4%).

Conclusions: IECFs are detected on myocardial perfusion PET/CT in approximately half of the patients. In the present study, IECFs were potentially clinically relevant in 8% of the patients and in 1.4% an unknown malignancy was found, most of which were lung cancers.