Differential centiloid scale normalization techniques: comparison between hybrid PET/MRI and independently acquired...

Area of Science:

• Neuroimaging
• Radiochemistry
• Biomarker Analysis

Background:

• Centiloid (CL) scales are crucial for semiquantitative analysis of amyloid-β (Aβ) positron emission tomography (PET) imaging.
• CL values are derived from standardized uptake value ratio (SUVR), necessitating T1-weighted imaging (T1WI) for normalization.
• Two T1WI acquisition methods exist: simultaneous (PET/MRI) and separate (PET+MRI).

Purpose of the Study:

• To investigate the correlation and differences in Centiloid (CL) values derived from amyloid-β (Aβ) PET imaging.
• To compare CL values obtained using T1-weighted imaging (T1WI) from simultaneous PET/MRI versus separate PET+MRI acquisitions for normalization.

Main Methods:

• Analyzed 49 patients who underwent Aβ PET/MRI (using ¹¹C-PiB or ¹⁸F-FMM) and additional MRI T1WI within 3 years.
• Normalized PET images using both simultaneous PET/MRI and separate PET+MRI methods.
• Calculated SUVR using standard templates and derived CL values for each tracer.

Main Results:

• Strong linear correlations (R² > 0.99) were observed between PET/MRI and PET+MRI methods for both tracers and acquisition types.
• Wilcoxon signed-rank tests showed no significant differences in CL values overall (p > 0.05), though some differences were noted for specific acquisition parameters.
• Bland-Altman analysis indicated minimal bias between the two normalization methods.

Conclusions:

• Anatomical standardization using PET/MRI and PET+MRI methods yields nearly equivalent Centiloid (CL) values.
• CL values derived from PET/MRI or PET+MRI normalization are consistent and comparable for clinical research applications.