Q.Clear重建对PET/MR一体机中18F-FDG PET定量及空间分辨率的影响
The effect of Q.Clear reconstruction on quantification and spatial resolution of 18F-FDG PET in simultaneous PET/MR.
作者信息
Tian Defeng, Yang Hongwei, Li Yan, Cui Bixiao, Lu Jie
机构信息
Department of Radiology and Nuclear Medicine, Xuanwu Hospital, Capital Medical University, 45# Changchun Street, Xicheng District, Beijing, China.
Beijing Key Laboratory of Magnetic Resonance Imaging and Brain Informatics, Beijing, China.
出版信息
EJNMMI Phys. 2022 Jan 10;9(1):1. doi: 10.1186/s40658-021-00428-w.
BACKGROUND
Q.Clear is a block sequential regularized expectation maximization penalized-likelihood reconstruction algorithm for Positron Emission Tomography (PET). It has shown high potential in improving image reconstruction quality and quantification accuracy in PET/CT system. However, the evaluation of Q.Clear in PET/MR system, especially for clinical applications, is still rare. This study aimed to evaluate the impact of Q.Clear on the F-fluorodeoxyglucose (FDG) PET/MR system and to determine the optimal penalization factor β for clinical use.
METHODS
A PET National Electrical Manufacturers Association/ International Electrotechnical Commission (NEMA/IEC) phantom was scanned on GE SIGNA PET/MR, based on NEMA NU 2-2012 standard. Metrics including contrast recovery (CR), background variability (BV), signal-to-noise ratio (SNR) and spatial resolution were evaluated for phantom data. For clinical data, lesion SNR, signal to background ratio (SBR), noise level and visual scores were evaluated. PET images reconstructed from OSEM + TOF and Q.Clear were visually compared and statistically analyzed, where OSEM + TOF adopted point spread function as default procedure, and Q.Clear used different β values of 100, 200, 300, 400, 500, 800, 1100 and 1400.
RESULTS
For phantom data, as β value increased, CR and BV of all sizes of spheres decreased in general; images reconstructed from Q.Clear reached the peak SNR with β value of 400 and generally had better resolution than those from OSEM + TOF. For clinical data, compared with OSEM + TOF, Q.Clear with β value of 400 achieved 138% increment in median SNR (from 58.8 to 166.0), 59% increment in median SBR (from 4.2 to 6.8) and 38% decrement in median noise level (from 0.14 to 0.09). Based on visual assessment from two physicians, Q.Clear with β values ranging from 200 to 400 consistently achieved higher scores than OSEM + TOF, where β value of 400 was considered optimal.
CONCLUSIONS
The present study indicated that, on F-FDG PET/MR, Q.Clear reconstruction improved the image quality compared to OSEM + TOF. β value of 400 was optimal for Q.Clear reconstruction.
背景
Q.Clear是一种用于正电子发射断层扫描（PET）的块序贯正则化期望最大化惩罚似然重建算法。它在提高PET/CT系统的图像重建质量和定量准确性方面显示出巨大潜力。然而，在PET/MR系统中对Q.Clear的评估，尤其是在临床应用方面，仍然很少见。本研究旨在评估Q.Clear对F-氟脱氧葡萄糖（FDG）PET/MR系统的影响，并确定临床使用的最佳惩罚因子β。
方法
根据NEMA NU 2-2012标准，在GE SIGNA PET/MR上扫描PET美国国家电气制造商协会/国际电工委员会（NEMA/IEC）体模。评估体模数据的对比度恢复（CR）、背景变异性（BV）、信噪比（SNR）和空间分辨率等指标。对于临床数据，评估病变SNR、信号与背景比（SBR）、噪声水平和视觉评分。对从有序子集最大期望值（OSEM）+飞行时间（TOF）和Q.Clear重建的PET图像进行视觉比较和统计分析，其中OSEM+TOF采用点扩散函数作为默认程序，Q.Clear使用100、200、300、400、500、800、1100和1400的不同β值。
结果
对于体模数据，随着β值增加，各种尺寸球体的CR和BV总体上降低；用Q.Clear重建的图像在β值为400时达到SNR峰值，并且通常比从OSEM+TOF重建的图像具有更好的分辨率。对于临床数据，与OSEM+TOF相比，β值为400的Q.Clear使中位数SNR提高了138%（从58.8提高到166.0），中位数SBR提高了59%（从4.2提高到6.8），中位数噪声水平降低了38%（从0.14降低到0.09）。根据两位医生的视觉评估，β值在200到400之间的Q.Clear始终比OSEM+TOF获得更高的分数,其中β值400被认为是最佳的。
结论
本研究表明，在F-FDG PET/MR上，与OSEM+TOF相比，Q.Clear重建提高了图像质量。β值400对于Q.Clear重建是最佳的。
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