Hybrid Cardiac ⁶⁸Ga-FAPI-4 PET/MRI in Dilated Cardiomyopathy: A Feasibility and Pilot Study.

Area of Science:

• Cardiovascular Imaging
• Molecular Imaging
• Nuclear Medicine

Background:

• Cardiac gallium 68-labeled fibroblast activation protein inhibitor (FAPI)-4 (⁶⁸Ga-FAPI-4) PET/MRI offers simultaneous assessment of cardiac tissue characteristics, function, and molecular remodeling in myocardial diseases.
• An integrated workflow for nonischemic dilated cardiomyopathy (DCM) using this modality is currently lacking.

Purpose of the Study:

• To evaluate the feasibility and diagnostic performance of a time-efficient cardiac ⁶⁸Ga-FAPI-4 PET/MRI protocol in participants with DCM.

Main Methods:

• A prospective study enrolled participants with DCM and healthy controls for hybrid ⁶⁸Ga-FAPI-4 PET/MRI.
• Oncology patients without cardiovascular disease undergoing ⁶⁸Ga-FAPI-4 PET/CT served as an additional control group.
• Hybrid PET/MRI included cine imaging, T1/T2 mapping, and late gadolinium enhancement (LGE); myocardial FAPI uptake was quantified and correlated with MRI and clinical markers.

Main Results:

• The hybrid protocol was feasible, with mean cardiac MRI acquisition and scanner room times of 32.0 ± 6.0 and 37.6 ± 6.6 minutes, respectively.
• Sixty-eight percent of DCM participants showed elevated myocardial FAPI uptake, exceeding LGE extent in 73% of positive cases.
• FAPI uptake was absent in healthy and oncology controls; excellent diagnostic performance for DCM was observed (AUCs ranging from 0.83 to 0.92).

Conclusions:

• Hybrid cardiac ⁶⁸Ga-FAPI-4 PET/MRI is a feasible and effective method for simultaneous molecular and structural imaging in nonischemic DCM.
• The protocol demonstrates high diagnostic accuracy for identifying DCM, correlating well with cardiac structure and function parameters.