Combined simultaneous FDG-PET/MRI with T1 and T2 mapping as an imaging biomarker for the diagnosis and prognosis of suspected cardiac sarcoidosis

Edward Cheung; Sarah Ahmad; Matthew Aitken; Rosanna Chan; Robert M Iwanochko; Meyer Balter; Ur Metser; Patrick Veit-Haibach; Filio Billia; Yasbanoo Moayedi; Heather J Ross; Kate Hanneman

doi:10.1186/s41824-021-00119-w

Combined simultaneous FDG-PET/MRI with T1 and T2 mapping as an imaging biomarker for the diagnosis and prognosis of suspected cardiac sarcoidosis

Eur J Hybrid Imaging. 2021 Dec 16;5(1):24. doi: 10.1186/s41824-021-00119-w.

Authors

Affiliations

¹ Department of Medical Imaging, Peter Munk Cardiac Centre, Toronto General Hospital, University of Toronto, 585 University Avenue, 1 PMB-298, Toronto, ON, M5G 2N2, Canada.
² Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, University of Toronto, 585 University Ave, Toronto, ON, M5G 2N2, Canada.
³ Division of Respiratory Medicine, Sinai Health System, University of Toronto, 600 University Ave, Toronto, ON, M5G 1X5, Canada.
⁴ Division of Molecular Imaging, Department of Medical Imaging, University Health Network, University of Toronto, 585 University Avenue, Toronto, ON, M5G 2N2, Canada.
⁵ Department of Medical Imaging, Peter Munk Cardiac Centre, Toronto General Hospital, University of Toronto, 585 University Avenue, 1 PMB-298, Toronto, ON, M5G 2N2, Canada. kate.hanneman@uhn.ca.

Abstract

Purpose: To evaluate the diagnostic and prognostic significance of combined cardiac ¹⁸F-fluorodeoxyglucose (FDG) PET/MRI with T1/T2 mapping in the evaluation of suspected cardiac sarcoidosis.

Methods: Patients with suspected cardiac sarcoidosis were prospectively enrolled for cardiac ¹⁸F-FDG PET/MRI, including late gadolinium enhancement (LGE) and T1/T2 mapping with calculation of extracellular volume (ECV). The final diagnosis of cardiac sarcoidosis was established using modified JMHW guidelines. Major adverse cardiac events (MACE) were assessed as a composite of cardiovascular death, ventricular tachyarrhythmia, bradyarrhythmia, cardiac transplantation or heart failure. Statistical analysis included Cox proportional hazard models.

Results: Forty-two patients (53 ± 13 years, 67% male) were evaluated, 13 (31%) with a final diagnosis of cardiac sarcoidosis. Among patients with cardiac sarcoidosis, 100% of patients had at least one abnormality on PET/MRI: FDG uptake in 69%, LGE in 100%, elevated T1 and ECV in 100%, and elevated T2 in 46%. FDG uptake co-localized with LGE in 69% of patients with cardiac sarcoidosis compared to 24% of those without, p = 0.014. Diagnostic specificity for cardiac sarcoidosis was highest for FDG uptake (69%), elevated T2 (79%), and FDG uptake co-localizing with LGE (76%). Diagnostic sensitivity was highest for LGE, elevated T1 and ECV (100%). After median follow-up duration of 634 days, 13 patients experienced MACE. All patients who experienced MACE had LGE, elevated T1 and elevated ECV. FDG uptake (HR 14.7, p = 0.002), elevated T2 (HR 9.0, p = 0.002) and native T1 (HR 1.1 per 10 ms increase, p = 0.044) were significant predictors of MACE even after adjusting for left ventricular ejection fraction and immune suppression treatment. The presence of FDG uptake co-localizing with LGE had the highest diagnostic performance overall (AUC 0.73) and was the best predictor of MACE based on model goodness of fit (HR 14.9, p = 0.001).

Conclusions: Combined cardiac FDG-PET/MRI with T1/T2 mapping provides complementary diagnostic information and predicts MACE in patients with suspected cardiac sarcoidosis.

Keywords: CMR; Cardiac MRI; Cardiac sarcoidosis; FDG PET; PET/MRI; Sarcoidosis.