Improved beta-amyloid PET reproducibility using two-phase acquisition and grey matter delineation

Area of Science:

• Neuroimaging
• Nuclear Medicine
• Radiochemistry

Background:

• Flutemetamol (FMM) Positron Emission Tomography (PET) is used for amyloid detection in neurodegenerative diseases.
• Standard visual reporting (STD) methods for FMM PET have limitations in reproducibility.
• Improving the reliability of FMM PET interpretation is crucial for accurate diagnosis.

Purpose of the Study:

• To evaluate if a novel grey matter edges (GM-EDGE) method improves the reproducibility of flutemetamol (FMM) PET interpretation compared to the standard visual reporting (STD) method.
• To assess the impact of the GM-EDGE method on inter-rater agreement and subjective confidence in amyloid positivity classification.

Main Methods:

• 121 patients with mild cognitive impairment underwent two-phase FMM PET scans.
• Five nuclear medicine physicians independently evaluated scans using both STD and GM-EDGE methods.
• Amyloid positivity was assessed using a five-point scale and binary classification, with subjective confidence ratings.

Main Results:

• The GM-EDGE method demonstrated higher inter-rater reliability (Cohen's kappa: 0.76-0.89 vs. 0.63-0.73; ICC: 0.91 vs. 0.84) and binary classification agreement (91.6% vs. 80.8%) compared to the STD method.
• Physicians reported significantly greater subjective confidence when using the GM-EDGE method.
• The GM-EDGE method showed improved agreement for both quantitative and qualitative assessments of amyloid positivity.

Conclusions:

• The GM-EDGE method significantly enhances inter-rater agreement and subjective confidence in flutemetamol PET interpretation for amyloid detection.
• This novel method is easily implementable in clinical practice, particularly when utilizing the perfusion phase.
• The GM-EDGE method offers a more reproducible and reliable approach to FMM PET analysis.