最大环差对全身PET/CT扫描仪图像质量和噪声特性的影响。

Impact of the maximum ring difference on image quality and noise characteristics of a total-body PET/CT scanner.

作者信息

Schmidt F P, Mannheim J G, Linder P M, Will P, Kiefer L S, Conti M, la Fougère C, Rausch I

机构信息

Department of Nuclear Medicine and Clinical Molecular Imaging, University hospital Tuebingen, Tuebingen, Germany; Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard-Karls University Tuebingen, Tuebingen, Germany.

Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard-Karls University Tuebingen, Tuebingen, Germany; Cluster of Excellence iFIT (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", University of Tuebingen, Tuebingen, Germany.

出版信息

Z Med Phys. 2023 Oct 20. doi: 10.1016/j.zemedi.2023.09.001.

DOI:10.1016/j.zemedi.2023.09.001

PMID:37867050

Abstract

UNLABELLED

The sensitivity of a PET system highly depends on the axial acceptance angle or maximum ring difference (MRD), which can be particularly high for total-body scanners due to their larger axial field of views (aFOVs). This study aims to evaluate the impact on image quality (IQ) and noise performance when MRD85 (18°), the current standard for clinical use, is increased to MRD322 (52°) for the Biograph Vision Quadra (Siemens Healthineers).

METHODS

Studies with a cylindrical phantom covering the 106 cm aFOV and an IEC phantom filled with F, Ga and Zr were performed for acquisition times from 60 to 1800 s and activity concentrations from 0.4 to 3 kBq/ml to assess uniformity, contrast recovery coefficients (CRCs) and to characterize noise by coefficient of variation (CV). Spatial resolution was compared for both MRDs by sampling a quadrant of the FOV with a point source. Further IQ, CV, liver SUV and SUV were compared for a cohort of 5 patients scanned with [F]FDG (3 MBq/kg, 1 h p.i.) from 30 to 300 s.

RESULTS

CV was improved by a factor of up to 1.49 and is highest for short acquisition times, peaks at the center field of view and mitigates parabolic in axial direction with no difference to MRD85 beyond the central 80 cm. No substantial differences between the two evaluated MRDs in regards to uniformity, SUV or CRC for the different isotopes were observed. A degradation of the average spatial resolution of 0.9 ± 0.2 mm in the central 40 cm FOV was determined with MRD322. Depending on the acquisition time MRD322 resulted in a decrease of SUV between 23.8% (30 s) and 9.0% (300 s).

CONCLUSION

Patient and phantom studies revealed that scan time could be lowered by approximately a factor of two with MRD322 while maintaining similar noise performance. The moderate degradation in spatial resolution for MRD322 is worth to exploit the full potential of the Quadra by either shorten scan times or leverage noise performance in particular for low count scenarios such as ultra-late imaging or dynamic studies with high temporal resolution.

摘要

未标注

PET系统的灵敏度高度依赖于轴向接受角或最大环差（MRD），由于全身扫描仪具有较大的轴向视野（aFOV），其轴向接受角或最大环差可能特别大。本研究旨在评估将临床使用的当前标准MRD85（18°）增加到Biograph Vision Quadra（西门子医疗）的MRD322（52°）时对图像质量（IQ）和噪声性能的影响。

方法

使用覆盖106厘米aFOV的圆柱形体模和填充有氟、镓和锆的IEC体模进行研究，采集时间从60秒到1800秒，活度浓度从0.4到3 kBq/ml，以评估均匀性、对比恢复系数（CRC），并通过变异系数（CV）表征噪声。通过用点源对视野的一个象限进行采样，比较两种MRD的空间分辨率。进一步比较了5名患者在30到300秒内用[氟]FDG（3 MBq/kg，注射后1小时）扫描时的IQ、CV、肝脏SUV和SUV。

结果

CV提高了高达1.49倍，在短采集时间时最高，在视野中心场达到峰值，并在轴向呈抛物线状减轻，在中心80厘米以外与MRD85无差异。在不同同位素的均匀性、SUV或CRC方面，未观察到两种评估的MRD之间有实质性差异。使用MRD322时，在中心40厘米视野内平均空间分辨率下降了0.9±0.2毫米。根据采集时间，MRD322导致SUV下降23.8%（30秒）至9.0%（300秒）。