# Toward Harmonizing Quantification of Dopamine Neuron Imaging Biomarkers in Parkinson's Disease: The Centamine Scale

## TL;DR

This paper introduces a standardized scale called Centamines to harmonize dopamine neuron imaging measurements in Parkinson's disease, enabling better clinical research.

## Contribution

The novel Centamines framework provides a unified scale for quantifying dopaminergic imaging biomarkers across different tracers.

## Key findings

- The Centamine scale was successfully established using healthy [123I]ioflupane SPECT scans.
- Mapped Centamine values showed minimal differences between [123I]ioflupane SPECT and [18F]AV133 PET tracers.
- Linear correlations between tracers ranged from moderate to strong (R² = 0.51–0.83) across brain regions.

## Abstract

Dopaminergic imaging is a key biomarker for both the investigation of the biology of Parkinson's disease and related synucleinopathies and the evaluation of potential therapies in clinical trials. This work presents a harmonized approach for quantifying dopaminergic molecular imaging tracers, such as [123I]ioflupane (dopamine transporter scan [DaTscan]) single photon emission computed tomography (SPECT) and [18F]AV133 positron emission tomography (PET), which assess dopaminergic neuronal loss. The proposed method aims to standardize regional outcome measures using a unified scale called Centamines.

The Centamines framework comprises 3 analysis levels. Level 1 defines the Centamine scale based on healthy subject data from [123I]ioflupane SPECT (n = 224). Level 2 uses head‐to‐head data between Tracer X and [123I]ioflupane SPECT to map Tracer X onto the Centamine scale. Level 3 maps additional tracers using prior mappings. A level 2 analysis was performed using [123I]ioflupane SPECT and [18F]AV133 PET data (n = 68) to convert [18F]AV133 PET into Centamines.

Level 1 successfully established the Centamine scale using healthy [123I]ioflupane SPECT scans. Level 2 revealed moderate‐strong linear correlations (R
2 = 0.51–0.83) between [123I]ioflupane SPECT and [18F]AV133 PET across 5 brain regions. Mapped Centamine values showed minimal differences between tracers, ranging from 1.5% (post‐commissural putamen) to 3% (caudate).

The Centamine scale holds promise for the harmonized quantification of dopaminergic neuronal imaging markers. The Centamine strategy would enable and accelerate clinical trials in Parkinson's disease using dopaminergic imaging outcomes. ANN NEUROL 2026;99:949–963