Original Article
Extracardiac findings with increased perfusion during clinical O-15-H2O PET/CT myocardial perfusion imaging: A case series

https://doi.org/10.1007/s12350-022-03156-5Get rights and content

Abstract

Background

Coincidental extracardiac findings with increased perfusion were reported during myocardial perfusion imaging (MPI) with various retention radiotracers. Clinical parametric O-15-H2O PET MPI yielding quantitative measures of myocardial blood flow (MBF) was recently implemented at our facility. We aim to explore whether similar extracardiac findings are observed using O-15-H2O.

Methods and results

All patients (2963) were scanned with O-15-H2O PET MPI according to international guidelines and extracardiac findings were collected. In contrast to parametric O-15-H2O MBF images, extracardiac perfusion was assessed using summed images. Biopsy histopathology and other imaging modalities served as reference standards. Various malignant lesions with increased perfusion were detected, including lymphomas, large-celled neuroendocrine tumour, breast, and lung cancer plus metastases from colonic and renal cell carcinomas. Furthermore, inflammatory and hyperplastic benign conditions with increased perfusion were observed: rib fractures, gynecomastia, atelectasis, sarcoidosis, pneumonia, chronic lung inflammation and fibrosis, benign lung nodule, chronic diffuse lung infiltrates, pleural plaques and COVID-19 infiltrates.

Conclusions

Malignant and benign extracardiac coincidental findings with increased perfusion are readily visible and frequently seen on O-15-H2O PET MPI. We recommend evaluating the summed O-15-H2O PET images in addition to the low-dose CT attenuation images.

Section snippets

Background

Ischemic heart disease is the leading cause of death worldwide, and hence, diagnosis and guidance of medical treatment and interventional revascularization are of great importance. In nuclear medicine, regional myocardial ischemia can be assessed by single-photon emission computed tomography (SPECT) or positron emission tomography (PET) with comparison of a rest and a stress scan (exercise or pharmacologically induced). Recently, myocardial perfusion flow imaging (MPI) using PET has proven

Methods

O-15-H2O PET MPI was implemented in daily clinical routine in May 2020. All scans were interpreted as routine clinical reads by a nuclear medicine specialist, and in most cases also by a resident doctor. Cases were collected consecutively during daily clinical work, especially since June 2021. Additionally, the reports of all scans were retrospectively reviewed, assessing the rate of coincidental findings.

All patients were scanned according to the standard clinical MPI protocol for O-15-H2O at

Results

In total, 2963 patients have undergone clinical O-15-H2O PET MPI at our department. 371 (13%) of these included reports of coincidental findings, generally findings on low-dose CT. 135 (36%) of the coincidental findings were unchanged lung nodules and 142 (38%) were various benign conditions. Benign lung conditions constitute the majority of benign findings, such as atelectasis, pleural effusion, pneumonia, pleural plaques, bullae, etc., but also cysts, fractures, hernia and benign mamma

Discussion

The present case series demonstrates various malignant and benign coincidental findings with increased perfusion, detected during clinical O-15-H2O PET MPI. PET imaging of tumour perfusion has been proposed as a potential cancer biomarker10 and has been studied with O-15-H2O PET in various malignancies including brain,11,12 head and neck,13,14 lung,15 breast,16,17 pancreas,18 cervix uteri,19 abdominal,20 and prostate cancer.21,22 Furthermore, increased perfusion has been described in studies

New knowledge gained

Benign and malignant coincidental extracardiac findings with increased perfusion are frequently encountered on O-15-H2O PET/CT. These coincidental findings and a discussion of indirect measures of adenosine response has not previously been described using O-15-H2O, but fits in line with the clinical experience from perfusion imaging with other PET tracers. The paper provides clinically relevant information for colleagues at PET-centers who perform cardiac PET, and especially those who consider

Conclusions

Both malignant and benign extracardiac coincidental findings with increased perfusion are readily visible and frequently encountered on summed O-15-H2O PET images. In most cases, the coincidental findings can be verified by lesions on the accompanying low-dose CT-scan. We therefore recommend evaluating summed O-15-H2O images in addition to the cardiac software’s display of parametric MBF images when doing an O-15-H2O MPI report.

Acknowledgements

Mads R Jochumsen was financially supported by NEYE-Fonden, Louis-Hansen Fonden and Fabrikant Einar Willumsens Mindelegat. Lars C Gormsen has an unrestricted grant from the Novo Nordisk Foundation (NNF19OC0055100).

Author contributions

All authors contributed with patient cases and/or technical and academic guidance. The manuscript was drafted by MRJ and TØB. All authors read, critically revised, and approved the final manuscript.

Disclosures

The authors MRJ, DLO, MHV, MAM, LPT, LCG and TØB declare that they have no disclosures.

Funding

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