# Spatial Distribution of Brain PET Tracers by MALDI Imaging

## TL;DR

This study shows that mass spectrometry imaging can effectively track PET tracer distribution in brain tissue without using radioactive materials.

## Contribution

The paper introduces an optimized sample preparation protocol for MALDI imaging that improves PET tracer detection and reduces ion suppression.

## Key findings

- A washing step in sample preparation enhanced the signal of PET tracers UCB-J and UCB2400.
- Calibration curves using tissue homogenates enabled accurate quantification of PET tracers.
- The optimized MALDI protocol minimizes ion suppression and improves spatial distribution analysis.

## Abstract

Evaluating tissue distribution of Positron Emission Tomography
(PET) tracers during their development conventionally involves autoradiography
techniques, where radioactive compounds are used for ex vivo visualization and quantification in tissues during preclinical development
stages. Mass Spectrometry Imaging (MSI) offers a potential alternative,
providing spatial information without the need for radioactivity with
a similar spatial resolution. This study aimed to optimize a MSI sample
preparation protocol for assessing PET tracer candidates ex
vivo with a focus on two compounds: UCB-J and UCB2400. We
tested different matrices and introduced washing steps to improve
PET tracer detection. Tissue homogenates were prepared to construct
calibration curves for quantification. The incorporation of a washing
step into the MSI sample preparation protocol enhanced the signal
of both PET tracers. Our findings highlight MSI’s potential
as a cost-effective and efficient method for the evaluation of PET
tracer distribution. The optimized approach offered here can provide
a protocol that enhances the signal and minimizes ion suppression
effect, which can be valuable for future evaluation of PET tracers
in MSI studies.