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

Our plain-English summary of Extracardiac findings with increased perfusion during clinical O-15-H2O PET/CT myocardial perfusion imaging: A case series, by M.R. Jochumsen, D.L. Overgaard, M.H. Vendelbo, et al (Journal of Nuclear Cardiology, 2023).

The study

• Authors: M.R. Jochumsen, D.L. Overgaard, M.H. Vendelbo, M.A. Madsen, L.P. Tolbod, L.C. Gormsen, T.Ø. Barkholt
• Journal: Journal of Nuclear Cardiology
• Published: 2023;30(4):1458-1468
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

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.

© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.

In plain English

This case series came from the Department of Nuclear Medicine and PET-Centre at Aarhus University Hospital, Denmark. It described findings outside the heart on heart blood-flow scans using radioactive water (O-15-H2O PET/CT), which the department began using in routine care in May 2020. Of 2963 patients scanned, 371 (13%) had reports noting incidental findings, mostly seen on the low-dose CT. Of these 371, 135 (36%) were unchanged lung nodules, 142 (38%) were various benign conditions and 94 (25%) were potential malignancies. In total, 106 (4%) patients had further testing. The authors described individual cases with increased blood flow, including breast and lung cancers, lymphomas and lung metastases, and benign conditions such as pneumonia, COVID-19 and healing rib fractures. One case was a 73-year-old man with pleural plaques, confirmed by CT, where the least calcified parts showed increased blood flow and other plaques showed low flow. The article does not mention asbestos or this man's exposure history. The authors concluded that such findings are readily visible and frequently seen. They recommended reviewing the summed PET images in addition to the low-dose CT.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case series from routine clinical scanning, with a retrospective review of all scan reports
• Who was studied: 2963 patients who had clinical O-15-H2O PET heart blood-flow (myocardial perfusion) scans at the Department of Nuclear Medicine and PET-Centre, Aarhus University Hospital, Denmark, after the method was introduced in May 2020; individual cases were described in detail
• Exposure: Not an asbestos exposure study. The study looked at O-15-H2O PET/CT myocardial perfusion imaging, with rest and adenosine stress scans. No asbestos exposure, fiber type or occupation is reported for any patient, including the pleural plaque case.
• Main results:
  • Of the 2963 patients, 371 (13%) had scan reports that included incidental findings, generally findings on the low-dose CT
  • Of the 371 reports with incidental findings, 135 (36%) were unchanged lung nodules and 142 (38%) were various benign conditions; benign lung conditions mentioned included atelectasis, pleural effusion, pneumonia and pleural plaques
  • 94 (25%) of the reports described potential malignancies, 81 of which were new or unknown lung nodules or ground glass opacities
  • Of the potential malignancies, 10 were described as highly suspicious of malignancy and 3 were enlarged lymph nodes
  • 106 (4%) of the 2963 patients had further (downstream) testing
  • In a 73-year-old man with known ischaemic heart disease, pleural plaques confirmed by CT showed increased blood flow in their least calcified parts, while other plaques had low blood flow
  • Malignant findings with increased blood flow in individual patients included primary breast cancer with an axillary lymph node metastasis, primary lung adenocarcinoma, a large-celled neuroendocrine tumour, lymphomas, and lung metastases from colon and renal cell carcinoma
  • In all cases but one, the findings outside the heart were visible on the low-dose CT; the exception was a breast cancer lying partly outside the CT field of view
• The authors' conclusion: The authors concluded that both malignant and benign findings outside the heart with increased blood flow are readily visible and frequently encountered on summed O-15-H2O PET images. They recommended evaluating these images in addition to the cardiac software's blood-flow images.
• Limitations the authors state:
  • Malignant lesions were more clearly defined on F-18-FDG PET/CT than on the summed O-15-H2O images, and the authors stated that the cardiac PET does not replace FDG PET/CT
  • The cardiac software masks out the lung, so only large, dense lung lesions could be seen on the parametric blood-flow images
  • An apparent lung perfusion defect on early images could not be confirmed as a lung embolus, so the authors considered examining early lung passage of the tracer currently of questionable clinical use

Topics

Medical terms in this study, explained in our Lexicon: Biopsy, Histopathology, Lung Cancer, Carcinoma, Atelectasis, Inflammation, Fibrosis, Pleural Plaques.

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