Evaluation of regularization factor and attenuation correction method of Q.Clear reconstruction for brain PET/MR in epileptic patients.

Abstract

Purpose: To identify suitable regularization factor β and attenuation correction (AC) method for Q.Clear reconstruction in brain [¹⁸F]FDG PET/MR imaging of patients with epilepsy.

Methods: We retrospectively collected 27 PET/MR brain images from patients with temporal lobe epilepsy. PET images were reconstructed using both ordered subset-expectation maximization and Q.Clear reconstruction (β from 50 to 600) with three AC methods: Atlas-based AC (Atlas-AC), Partial Head-based AC (PH-AC), and Zero Echo Time-based AC (ZTE-AC). Image quality was assessed using lesion-to-background (LBR) ratio, normalized standard deviation (NSD) ratio, SUV_max, and SUV_mean.

Results: Q.Clear reconstruction with β values of 50 to 600 significantly increased LBR and decreased NSD compared to OSEM. β value of 300 served as a practical operating point for the three AC methods. ZTE-AC had the largest LBR and lower NSD values, PH-AC method had the lowest NSD and relatively high LBR, while Atlas-AC showed moderate performance. Comparisons of SUV_max and SUV_mean between Q.Clear (β = 300) and OSEM across all AC methods suggest that β = 300 improves lesion contrast and reduces image noise without compromising SUV value.

Conclusions: Q.Clear reconstruction can improve lesion contrast and reduce noise compared to OSEM. ZTE-AC yielded the highest lesion contrast and LBR among three AC methods, PH-AC resulted in the lowest background noise, and Atlas-AC showed balanced but suboptimal performance. These findings offer practical guidance in selecting the suitable β value and AC method for optimized brain PET/MR imaging in patients with epilepsy.