Baldassi Brandon, Poladyan Harutyun, Shahi Anirudh, Maa-Hacquoil Henry, Rapley Madeline, Komarov Borys, Stiles Justin, Freitas Vivianne, Waterston Michael, Aseyev Olexiy, Reznik Alla, Bubon Oleksandr
Department of Physics, Lakehead University, Thunder Bay, ON, Canada.
Radialis Inc., Thunder Bay, ON, Canada.
Front Oncol. 2024 Mar 25;14:1268991. doi: 10.3389/fonc.2024.1268991. eCollection 2024.
A newly developed clinical organ-targeted Positron Emission Tomography (PET) system (also known as Radialis PET) is tested with a set of standardized and custom tests previously used to evaluate the performance of Positron Emission Mammography (PEM) systems.
Imaging characteristics impacting standardized uptake value (SUV) and detectability of small lesions, namely spatial resolution, linearity, uniformity, and recovery coefficients, are evaluated.
In-plane spatial resolution was measured as 2.3 mm ± 0.1 mm, spatial accuracy was 0.1 mm, and uniformity measured with flood field and NEMA NU-4 phantom was 11.7% and 8.3% respectively. Selected clinical images are provided as reference to the imaging capabilities under different clinical conditions such as reduced activity of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (F-FDG) and time-delayed acquisitions. SUV measurements were performed for selected clinical acquisitions to demonstrate a capability for quantitative image assessment of different types of cancer including for invasive lobular carcinoma with comparatively low metabolic activity. Quantitative imaging performance assessment with phantoms demonstrates improved contrast recovery and spill-over ratio for this PET technology when compared to other commercial organ-dedicated PET systems with similar spatial resolution. Recovery coefficients were measured to be 0.21 for the 1 mm hot rod and up to 0.89 for the 5 mm hot rod of NEMA NU-4 Image Quality phantom.
Demonstrated ability to accurately reconstruct activity in tumors as small as 5 mm suggests that the Radialis PET technology may be well suited for emerging clinical applications such as image guided assessment of response to neoadjuvant systemic treatment (NST) in lesions smaller than 2 cm. Also, our results suggest that, while spatial resolution greatly influences the partial volume effect which degrades contrast recovery, optimized count rate performance and image reconstruction workflow may improve recovery coefficients for systems with comparable spatial resolution. We emphasize that recovery coefficient should be considered as a primary performance metric when a PET system is used for accurate lesion size or radiotracer uptake assessments.
一种新开发的临床器官靶向正电子发射断层扫描（PET）系统（也称为桡动脉PET）使用一组先前用于评估正电子发射乳腺断层摄影（PEM）系统性能的标准化和定制测试进行测试。
评估影响标准化摄取值（SUV）和小病灶可检测性的成像特性，即空间分辨率、线性、均匀性和恢复系数。
平面内空间分辨率测量为2.3毫米±0.1毫米，空间精度为0.1毫米，使用泛源场和NEMA NU-4体模测量的均匀性分别为11.7%和8.3%。提供了选定的临床图像，作为不同临床条件下成像能力的参考，如2-[氟-18]-氟-2-脱氧-D-葡萄糖（F-FDG）活性降低和延迟采集。对选定的临床采集进行了SUV测量，以证明对不同类型癌症进行定量图像评估的能力，包括代谢活性相对较低的浸润性小叶癌。与其他具有相似空间分辨率的商用器官专用PET系统相比，使用体模进行的定量成像性能评估表明，该PET技术的对比度恢复和溢出率有所提高。对于NEMA NU-4图像质量体模的1毫米热棒，恢复系数测量为0.21，对于5毫米热棒，恢复系数高达0.89。
能够准确重建小至5毫米肿瘤中的活性，这表明桡动脉PET技术可能非常适合新兴的临床应用，如对小于2厘米的病灶进行新辅助全身治疗（NST）反应的图像引导评估。此外，我们的结果表明，虽然空间分辨率极大地影响降低对比度恢复的部分容积效应，但优化的计数率性能和图像重建工作流程可能会提高具有可比空间分辨率的系统的恢复系数。我们强调，当PET系统用于准确的病灶大小或放射性示踪剂摄取评估时，恢复系数应被视为主要性能指标。
