Image quality assessment of automatic three-segment MR attenuation correction vs. CT attenuation correction

Area of Science:

• Medical Imaging
• Radiology
• Nuclear Medicine

Background:

• Positron emission tomography/Computed tomography (PET/CT) is a standard imaging modality.
• Positron emission tomography/Magnetic resonance imaging (PET/MRI) offers potential advantages but requires robust attenuation correction methods.
• CT-based attenuation correction (CTAC) is the current standard, while MR-based attenuation correction (MRAC) is an alternative for PET/MRI.

Purpose of the Study:

• To systematically evaluate the clinical usefulness of PET/MRI by comparing the image quality of PET images using three-segment MRAC versus standard CTAC.
• To assess the diagnostic performance and image quality of PET/MRI in a clinical setting.

Main Methods:

• Prospective study of 48 patients undergoing FDG-PET/CT followed by FDG-PET/MRI.
• Image quality assessment by three nuclear radiologists using a five-point Likert scale and categorization into acceptable/unacceptable.
• Statistical analysis included paired t-tests and McNemar tests to compare CTAC and MRAC image quality.

Main Results:

• One reader found a significant difference in Likert scale scores between CTAC and MRAC (p=0.0015), while others did not (p>0.18).
• No significant difference in acceptable/unacceptable image quality categorization between CTAC and MRAC for any reader (p>0.61).
• Artifacts were reported more frequently on MRAC images than CTAC images.

Conclusions:

• PET/MRI demonstrated no clinically significant difference in image quality compared to PET/CT.
• The three-segment MRAC method provided diagnostic image quality for PET imaging.
• Further research on different MR attenuation correction methods is warranted before routine clinical use of PET/MRI.