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The Early Perfusion Image Is Useful to Support the Visual Interpretation of Brain Amyloid-PET With 18F-Flutemetamol
Franziska L Mathies1, Fiona Heeman, Pieter Jelle Visser
1From the Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Purpose:
Visual interpretation of brain amyloid-β (Aβ) PET can be difficult in individuals with borderline Aβ burden. Coregistration with individual MRI is recommended in these cases, which, however, is not always available. This study evaluated coregistration with the early perfusion frames acquired immediately after tracer injection to support the visual interpretation of the late Aβ-frames in PET with 18F-flutemetamol (FMM).
Patients And Methods:
Fifty dual-time-window FMM-PET scans of cognitively normal subjects with 0 to 60 Centiloids were included retrospectively (70.1 ± 6.9 years, 56% female, MMSE score 28.9 ± 1.3, 42% APOE ɛ4 carrier). Regional Aβ load was scored with respect to a 6-point Likert scale by 3 independent raters in the 10 regions of interest recommended for FMM reading using 3 different settings: Aβ image only, Aβ image coregistered with MRI, and Aβ image coregistered with the perfusion image. The impact of setting, within- and between-readers variability, region of interest, and Aβ-status was tested by repeated-measure analysis of variance of the Likert score.
Results:
The Centiloid scale ranged between 2 and 52 (interquartile range, 7-19). Support of visual scoring by the perfusion image resulted in the best discrimination between Aβ-positive and Aβ-negative cases, mainly by improved certainty of excluding Aβ plaques in Aβ-negative cases (P = 0.030). It also resulted in significantly higher between-rater agreement. The setting effect was most pronounced in the frontal lobe and in the posterior cingulate cortex/precuneus area (P = 0.005).
Conclusions:
The early perfusion image is a suitable alternative to T1-weighted MRI to support the visual interpretation of the late Aβ image in FMM-PET.
Insights
Early perfusion imaging in 18F-flutemetamol (FMM) PET scans aids visual interpretation of brain amyloid-beta (Aβ) burden. This method improves Aβ-negative case classification and reader agreement, offering an alternative to MRI.
Area of Science:
- Neuroimaging
- Nuclear Medicine
- Alzheimer's Disease Research
Background:
- Visual interpretation of brain amyloid-beta (Aβ) Positron Emission Tomography (PET) can be challenging in cases with borderline Aβ burden.
- Coregistration with individual Magnetic Resonance Imaging (MRI) is recommended but not always available.
Purpose of the Study:
- To evaluate the utility of coregistration with early perfusion frames from 18F-flutemetamol (FMM) PET scans.
- To determine if perfusion imaging can support visual interpretation of late Aβ-PET frames, serving as an alternative to MRI.
Main Methods:
- Retrospective analysis of 50 dual-time-window FMM-PET scans from cognitively normal subjects with varying Aβ burden (0-60 Centiloids).
- Three independent raters scored regional Aβ load using a 6-point Likert scale on Aβ images alone, Aβ images coregistered with MRI, and Aβ images coregistered with early perfusion images.
- Statistical analysis (repeated-measure ANOVA) assessed the impact of imaging setting, reader variability, region of interest, and Aβ status.
Main Results:
- Coregistration with early perfusion images provided the best discrimination between Aβ-positive and Aβ-negative cases, particularly by increasing certainty in excluding Aβ plaques in negative cases (P=0.030).
- Using perfusion images significantly improved between-rater agreement.
- The effect of imaging setting was most pronounced in the frontal lobe and posterior cingulate cortex/precuneus (P=0.005).
Conclusions:
- Early perfusion imaging in FMM-PET is a viable alternative to T1-weighted MRI.
- This method effectively supports the visual interpretation of late Aβ-PET images, enhancing diagnostic accuracy and consistency.
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