Improved clinical workflow for simultaneous whole-body PET/MRI using high-resolution CAIPIRINHA-accelerated MR-based...

Area of Science:

• Medical Imaging
• Radiology
• Nuclear Medicine

Background:

• Whole-body PET/MRI combines anatomical and functional imaging.
• Accurate attenuation correction (AC) is crucial for quantitative PET imaging.
• Current AC methods may have limitations in speed and resolution.

Purpose of the Study:

• To evaluate a novel CAIPIRINHA-accelerated T1-weighted Dixon 3D-VIBE sequence for magnetic resonance-based attenuation correction (MRAC).
• To compare the value and reproducibility of this novel MRAC (MRAC_caipi) against the standard MRAC (MRAC_std) in whole-body PET/MRI.

Main Methods:

• PET/MRI data from 19 patients were reconstructed using both standard and novel MRAC techniques.
• Standardized uptake values (SUV_mean) were calculated for various regions of interest (ROIs) and compared.
• Voxel-wise SUV analysis and Bland-Altman plots assessed inter-method agreement.
• Image quality and segmentation accuracy were evaluated by expert readers.

Main Results:

• High linearity and correlation were observed between SUV_mean values from both MRAC methods.
• Outliers were attributed to physiological variations and motion artifacts between scans.
• The novel MRAC_caipi demonstrated improved segmentation of air-containing tissues like sinuses and trachea.
• High diagnostic image quality was achieved with MRAC_caipi, showing excellent inter-reader agreement.

Conclusions:

• The novel prototype MRAC_caipi provides a high-resolution, DIXON-based dataset suitable for diagnostic assessment in whole-body PET/MRI.
• This technique enhances the value of attenuation correction, contributing to time-efficient whole-body PET/MRI procedures.