Cardiac motion and spillover correction for quantitative PET imaging using dynamic MRI.

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Cardiovascular Imaging

Background:

• Cardiac positron emission tomography/magnetic resonance imaging (PET/MRI) combines viability and metabolic imaging with functional and structural imaging.
• Image quality and quantitative accuracy in cardiac PET/MRI are compromised by PET resolution and cardiac/respiratory motion.
• Standard gated reconstruction methods to address motion introduce higher noise levels.

Purpose of the Study:

• To develop and apply a novel correction method for quantitative PET imaging in cardiac PET/MRI.
• To overcome limitations in image quality and quantitative bias caused by motion in cardiac PET/MRI.
• To improve the accuracy of metabolic assessments in myocardial infarction patients.

Main Methods:

• A correction approach inspired by brain PET methods was adapted for cardiac PET/MRI.
• The method utilizes MRI-derived density maps to model activity recovery and cross-contamination coefficients.
• Linear equations are solved to determine true activity values, validated with physical and numerical phantoms.
• The method was applied to patient data using [11C]-acetate and compared to electrocardiography (ECG)-gated approaches with [18F]-FDG.

Main Results:

• The proposed method significantly improved recovery (32% to 95%) and reduced residual activity compared to standard methods.
• Enhanced signal-to-noise ratio (SNR) from 2.92 to 5.24 and contrast-to-noise ratio (CNR) from 62.9 to 145.9 were observed.
• Correction using [11C]-acetate PET data in patients led to expected clinical results, avoiding erroneous conclusions from uncorrected data.

Conclusions:

• An efficient and simple method for correcting quantitative biases in PET due to cardiac motion has been developed.
• Validation with phantom and patient data demonstrated improved accuracy and reliability over gated acquisition or ROI strategies.
• This approach offers a more dependable quantitative analysis for cardiac PET/MRI applications.