# Comparison of the Correlation Between Cerebral [18F]FDG Metabolism as Assessed by Two Asymmetry Indices and Clinical Neurological Score in Patients with Ischemic Cerebrovascular Disease

## TL;DR

This study compares two methods for measuring brain metabolism in stroke patients and finds one method better correlates with clinical scores.

## Contribution

The study introduces a novel comparison of two asymmetry indices for cerebral metabolism in ischemic stroke patients.

## Key findings

- AI2 detected larger hypometabolism volumes than AI1 in stroke patients.
- AI1 showed stronger correlations between brain metabolism and clinical scores in temporal and parietal lobes.
- Follow-up patients showed more metabolic improvement when assessed by AI1.

## Abstract

Two types of asymmetry index (AI) have been utilized in evaluating cerebral function in ischemic cerebrovascular disease, however, few data exist on the differences between these AI measures. This study aimed to compare the two AIs in assessing PET cerebral metabolism and their correlation with clinical scales, to explore their potential value and applications in clinical settings.

Seventy patients diagnosed with subacute and chronic ischemic stroke were retrospectively analyzed. All patients underwent 2-deoxy- 2-[18F]fluoro-D-glucose ([18F]FDG) PET/MR scans and were assessed using the National Institutes of Health Stroke Scale (NIHSS) and the Modified Rankin Scale (mRS). Nineteen patients underwent a repeat [18F]FDG PET/MR scan one year later. Two voxel-wise AI methods, designated as AI1 and AI2, were calculated based on standardized uptake value ratio (SUVR). The hypometabolism on affected side assessed by different AI methods were compared. The correlations between the hypometabolism and the clinical scores were analyzed.

The volume and percentage of decreased [18F]FDG metabolism assessed by AI2 was larger than that obtained from AI1 (all p < 0.0001). The correlation coefficients between the clinical scores and the decreased metabolism in temporal and parietal lobes assessed by AI1 method were all higher than those from AI2. In addition, the improved follow-up patients showed more pronounced metabolic improvement as assessed by AI1.

The assessment of cerebral [18F]FDG metabolism in patients with unilateral internal carotid/middle cerebral artery steno-occlusion to reflect clinical neurological function using the AI1 method demonstrated superior performance in comparison to the AI2 method.

The online version contains supplementary material available at 10.1007/s11307-025-02002-7.