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. 2026 Jan 20;16(1):30.
doi: 10.1186/s13550-026-01380-5.

Optimizing PET/CT protocols: is 60-minute [18 F]F-FDG uptake sufficient for cardiac sarcoidosis?

Giulia Metzger  1   1 , Bettina Heidecker  2 , Jonas Kaufmann  3 , Markus Galler  3 , Christian Bayerl  3   4 , Hans Jochens  3 , Norman Limberg  3 , Imke Schatka  3 , Thula Cannon Walter-Rittel  4 , Julian Rogasch  3 , Winfried Brenner  3 , Ulf Landmesser  2 , Holger Amthauer  3 , Christian Furth  3
Affiliations

Optimizing PET/CT protocols: is 60-minute [18 F]F-FDG uptake sufficient for cardiac sarcoidosis?

Giulia Metzger et al. EJNMMI Res. .

Abstract

Background: [18F]F-FDG PET/CT is an established imaging modality for diagnosing cardiac sarcoidosis (CS). While a 90-minute uptake time is commonly recommended to enhance target-to-background ratio, its added diagnostic value remains unclear. This study aimed to compare the diagnostic performance of 60-minute versus 90-minute uptake times. Eighty-seven patients (45 females, 42 males) with suspected CS underwent whole-body FDG PET/CT at 60 min post-injection (p.i.), followed by an additional chest scan at 90 min p.i. Patient preparation included a low-carbohydrate diet, prolonged fasting, and weight-based heparin administration. Three blinded readers with varying experience independently assessed the scans using binary classification for typical sarcoidosis-related FDG uptake, provided adequate myocardial glucose suppression was achieved. Inter- and intrarater agreement were analyzed using Fleiss' and Cohen's κ, respectively. Diagnostic accuracy was determined by majority vote, using Japanese Circulation Society (JCS) criteria as the reference standard.

Results: Interrater agreement was substantial (Fleiss' κ = 0.690-0.693), and intrarater agreement ranged from substantial to almost perfect (Cohen's κ = 0.703-0.899). Among patients with sufficient myocardial suppression, diagnostic accuracy was 97% (n = 62) at 60 min and 92% (n = 65) at 90 min. No statistically significant differences were observed between the two time points (p = 0.22).

Conclusion: FDG PET/CT with a 60-minute uptake time offers diagnostic accuracy comparable to that of a 90-minute uptake for CS detection, provided adequate myocardial suppression is achieved. Shorter uptake protocols may streamline workflow and improve patient comfort without compromising diagnostic integrity.

Keywords: Cardiac sarcoidosis; Diagnostic accuracy; FDG PET/CT; Reliability; Uptake time.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of Charité – Universitätsmedizin Berlin (EA4/106/24). Informed consent was obtained from all individual participants included in the study. Consent for publication: The authors affirm that human research participants provided informed consent for publication of the images in Figs. 1A-G and 2A-G. Competing interests: The authors have no relevant financial or non-financial interests to disclose. M.D. Imke Schatka serves as Guest Editor for the FAPI section of EJNMMI Research but was not involved in the editorial handling or review of this manuscript and has no competing interests related to this submission.

Figures

Fig. 1
Fig. 1
[18F]F-FDG PET/CT in patient 28 with suspected isolated CS. A-C transaxial, coronar and sagittal PET/CT fusion after 60 min of FDG uptake time. D maximum intensity projection. E-G transaxial, coronar and sagittal PET/CT fusion after 90 min of FDG uptake time. Intensive focal FDG uptake in the basal and apical septum with involvement of the right ventricle
Fig. 2
Fig. 2
[18F]F-FDG PET/CT in patient 71 with suspected cardiac involvement in proven extraCS. A-C transaxial, coronar and sagittal PET/CT fusion after 60 min of FDG uptake time. D maximum intensity projection. E-G transaxial, coronar and sagittal PET/CT fusion after 90 min of FDG uptake time. No FDG uptake is detected. Extracardiac involvement is shown by hypermetabolism of bihilary lymph nodes
See this image and copyright information in PMC

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