Coronary Artery PET/MR Imaging: Feasibility, Limitations, and Solutions

Area of Science:

• Cardiovascular Imaging
• Nuclear Medicine
• Radiochemistry

Background:

• Positron emission tomographic (PET) imaging, particularly with 18F-fluorodeoxyglucose (18F-FDG) and 18F-sodium fluoride (18F-NaF), is increasingly used for atherosclerosis and microcalcification.
• Coronary PET imaging is challenging due to vessel size and motion, with PET/computed tomography (CT) being standard.
• PET/magnetic resonance (MR) imaging offers potential benefits like reduced radiation and motion correction, alongside complementary cardiac MR data.

Purpose of the Study:

• To report initial experience with combined coronary artery PET/MR imaging.
• To identify and solve common challenges in coronary PET/MR imaging.
• To demonstrate the feasibility of this technique in selected patients.

Main Methods:

• Twenty-three patients with coronary artery disease risk factors underwent 18F-FDG or 18F-NaF PET/MR imaging.
• Compared standard breath-held MR-based attenuation correction with a novel free-breathing approach.
• Evaluated PET image artifacts, vascular uptake, and reconstruction algorithms (iterations).

Main Results:

• Free-breathing attenuation correction significantly improved image quality.
• Increasing PET reconstruction iterations enhanced coronary uptake conspicuity.
• Elevated radiotracer uptake was localized to coronary lesions using both 18F-FDG and 18F-NaF, including in a post-myocardial infarction plaque.

Conclusions:

• This study presents the first successful demonstration of low-radiation (7.2 mSv) coronary artery PET/MR imaging.
• The technique visualizes inflammation and microcalcification activity in coronary arteries.
• Specialized approaches for attenuation correction and PET reconstruction are necessary for coronary imaging.