New objective simple evaluation methods of amyloid PET/CT using whole-brain histogram and Top20%-Map.

Area of Science:

• Nuclear Medicine
• Neuroimaging
• Biomarkers

Background:

• Amyloid deposition in the brain is a hallmark of Alzheimer's disease.
• Accurate assessment of amyloid burden is crucial for diagnosis and monitoring disease progression.
• Current methods for amyloid PET analysis often rely on region-of-interest (ROI) analyses, which can be complex and time-consuming.

Purpose of the Study:

• To evaluate novel objective methods for assessing intracranial abnormal amyloid deposition using PET/CT histogram analysis.
• To determine the utility of these new methods without the need for cortical ROI analyses.
• To compare the performance of these new methods with conventional visual assessment and quantitative analyses.

Main Methods:

• Retrospective analysis of ¹⁸F-FPYBF-2 PET/CT scans from 25 healthy volunteers and 38 patients with dementia.
• Inclusion of ¹¹C-PiB PET/CT data from 13 subjects for cross-tracer comparison.
• Evaluation using novel histogram-derived parameters: skewness, mode-to-mean ratio (MMR), and Top20%-Map, alongside conventional visual assessment and composite standardized uptake value ratio (comSUVR).

Main Results:

• Visually positive amyloid PET scans correlated with significantly lower skewness and higher MMR (p<0.0001).
• The Top20%-Map effectively identified abnormal amyloid deposits.
• New histogram methods showed good correlation with visual assessment and comSUVR, and were consistent between ¹⁸F-FPYBF-2 and ¹¹C-PiB tracers.

Conclusions:

• Novel histogram-based methods for brain parenchymal amyloid accumulation are simple and clinically applicable for amyloid PET.
• The Top20%-Map, used with individual brain CT, significantly aids visual assessment of amyloid deposition.
• These objective methods offer a promising alternative to traditional ROI-based analyses in clinical practice.