PET in cardiac sarcoidosis: how inflammation, scarring and treatment response are assessed

Website publication date: 14 October 2026.
Date of the original article: 7 October 2026 (online publication)

Introduction
A new review in PET Clinics describes the role of 18F-FDG PET, combined with perfusion assessment, in the evaluation of suspected cardiac sarcoidosis and the follow-up of patients with confirmed disease. It focuses on distinguishing active inflammation from scarring and on interpreting findings cautiously.

Extended summary
Cardiac sarcoidosis may be associated with conduction disorders, ventricular arrhythmias and heart failure, but diagnosis can be challenging. The review explains that 18F-FDG PET is not interpreted in isolation: physiological glucose uptake in the heart muscle must be appropriately suppressed, and the findings are considered alongside perfusion imaging and clinical data.

A pattern of increased FDG uptake with preserved perfusion may indicate inflammatory activity without clear scarring. Uptake accompanied by a perfusion defect may reflect a combination of inflammation and fibrosis, while a perfusion defect without uptake may reflect predominantly scarring. The review states that studies have associated abnormal uptake, particularly when accompanied by a perfusion defect, with a higher risk of adverse cardiac events, including arrhythmias and death.

Serial PET imaging may help monitor the response to immunosuppressive treatment and detect reactivation of myocardial inflammation. However, this does not mean that a single PET finding determines the diagnosis or treatment on its own.

What is new
The review integrates PET with perfusion, clinical assessment and other cardiac imaging methods when evaluating the activity and consequences of cardiac sarcoidosis. It particularly emphasises that the quality of patient preparation and standardisation of interpretation directly affect the reliability of findings.

Why it matters to patients and doctors
For patients, the text explains why several tests are often combined when cardiac sarcoidosis is suspected and why a finding must not be interpreted outside its clinical context. For doctors, the review provides a concise framework for relating inflammatory activity, fibrosis, arrhythmia risk and monitoring of treatment response.

Limitations of the evidence
This is a review article, rather than a new randomised clinical trial. The accuracy and usefulness of PET depend on patient preparation, the protocol, the availability of perfusion imaging and the centre's experience. Associations between PET patterns and outcomes do not mean that PET alone predicts the course of disease in an individual.

Conclusion
18F-FDG PET combined with perfusion assessment may provide important information about possible inflammatory activity, fibrosis and the response to treatment for cardiac sarcoidosis. The findings must be assessed alongside symptoms, ECG, echocardiography, cardiac MRI and other relevant data.

Source and bibliographic details
Patel CD, Tilak A, Shiva C. PET in Cardiac Sarcoidosis. PET Clinics. Published online 7 October 2026. DOI: 10.1016/j.cpet.2026.08.004. PMID: 42844072.
Source: https://www.pet.theclinics.com/article/S1556-8598(26)00109-4/fulltext

Medical note
This text is for information and does not replace a medical examination, diagnosis or individual advice. PET findings must not be interpreted on their own, and treatment must not be started, stopped or changed without consulting a doctor.

Suggested illustration
A schematic view of the heart with two discreetly marked regions — active inflammation and scarring — alongside a PET/CT symbol; no actual patient images.
Accessible image description: “Schematic illustration of the assessment of cardiac sarcoidosis using PET/CT, distinguishing possible inflammation from scarring.”