# Clinical Utility of Amino Acid PET-MRI in Children with CNS Neoplasms: A Territory-Wide Study from Hong Kong

## TL;DR

A study in Hong Kong shows that amino acid PET-MRI improves brain tumor diagnosis and treatment decisions in children compared to standard MRI.

## Contribution

The study provides measurable cut-off values for amino acid PET-MRI to distinguish high-grade from low-grade pediatric brain tumors.

## Key findings

- High-grade lesions showed significantly higher SUVmax and TBRmax compared to low-grade/non-malignant lesions.
- Amino acid PET-MRI influenced treatment decisions in 69% of cases.
- Optimal SUVmax and TBRmax cut-offs were identified for tumor classification.

## Abstract

This study highlights the value of amino acid positron emission tomography–magnetic resonance imaging (PET-MRI) in improving the diagnosis and management of brain tumours in children. Unlike standard MRI, which lacks information on metabolic activities, this advanced imaging technique helps distinguish high-grade brain tumours from low-grade lesions or non-malignant lesions. Measurable cut-off points to differentiate between the two types of processes were obtained, which can aid future research in tumour classification. The study also showed that amino acid PET-MRI influenced treatment decisions in 69% of cases in a territory-wide referral centre, suggesting its strong clinical relevance. For the research community, this work supports the broader use of amino acid PET-MRI in paediatric neuro-oncology and encourages further studies to refine non-invasive diagnostic tools and improve personalized treatment planning. It sets the stage for prospective, multicentre studies and contributes valuable data to the growing field of hybrid imaging in childhood brain tumours.

Background: Amino acid tracer positron emission tomography–magnetic resonance imaging (PET-MRI) was shown to be superior to MRI alone for evaluating central nervous system (CNS) tumours in adults. This study aimed to investigate the utility of amino acid PET-MRI in children with CNS tumours. Methods: We reviewed the amino acid PET-MRI findings of children with suspected or confirmed CNS neoplasms managed in a territory-wide referral centre in Hong Kong from 2022 to 2025. Maximal standardized uptake values (SUVmax) were captured, and tumour-to-background SUVmax ratios (TBRmax) were measured with reference to adjacent or contralateral normal brain structures. Comparisons were made among patients with clinical high-grade and low-grade/non-neoplastic lesions. Results: Thirty-seven patients were included, with 63 PET-MRIs performed. PET-MRI was performed as part of initial diagnostics in 41% of the cases, for response assessment in 48%, and evaluation of residual/relapsed disease in 11%. High-grade lesions had a significantly higher SUVmax and TBRmax compared to low-grade/non-malignant lesions (median SUVmax 3.7 vs. 1.6, p = 0.00006; median TBRmax 2.06 vs. 0.91, p = 0.00002). Optimal SUVmax and TBRmax cut-offs by ROC analysis were 2.38 and 1.62, respectively. Similar performance was reproduced by focusing on the subset of patients with suspected CNS germ cell tumours (CNS-GCT). The impact of amino acid PET availability is considerable, as clinical management was modified in 65% of patients. Conclusions: Our study demonstrates the performance and clinical utility of amino acid PET-MRI in the management of children with CNS pathologies. Amino acid PET-MRI contributes to the diagnosis, monitoring, and treatment guidance of these patients, providing crucial information for decision-making.