Performance Evaluation of SmartBrain: A Wearable PET System for Human Brain Imaging

Background. Positron Emission Tomography (PET) is a vital medical imaging tool for studying in vivo metabolism. However, conventional PET systems are limited in their inability to image during free movement. Therefore, we have developed a wearable brain PET system for real-time imaging, called SmartBrain. Methods. The SmartBrain used 192 detectors and the detector consists of a 6 × 6 lutetium-yttrium oxyorthosilicate crystal (3 × 3 × 5 mm3) array with 3 × 3 silicon photomultipliers array. We evaluated the physical performance of SmartBrain according to the National Electrical Manufacturers Association (NEMA) NU 2-2018 standard. In addition, we performed 18F-FDG imaging using a custom Hoffman brain phantom and a multi-layer Derenzo phantom. Dynamic rat images and the 18F-FDG images from a healthy volunteer are presented. Results. Spatial resolution is 2.29 mm in center of field of view (FOV). The sensitivity was 720.15 cps/MBq. The peak noise-equivalent count rate was 4.67 kcps at 10.11 kBq/ml, and the scatter fraction was 29.53%. The NEMA image-quality contrast recovery coefficients varied from 72.85% (10-mm sphere) to 89.40% (37-mm sphere), and background variability was 11.25% at a contrast of 9.36:1. The time-of-flight (TOF) resolution was 234.22 ps, and the energy resolution was 10.81%. The SmartBrain showed that the main structures of Hoffman brain phantom could be resolved and demonstrated the ability to separate rods as small as 1.7 mm. In addition, an example of the structure of the human brain was demonstrated. Conclusion. The SmartBrain clearly demonstrated brain structures, confirming its suitability for clinical brain research. Moreover, as a wearable and mobile PET platform, it offers unique opportunities for naturalistic brain imaging and future clinical applications in the diagnosis and management of neurological disorders.