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

Brain PET is a powerful imaging modality that directly reflects cerebral metabolic activity, making it an essential tool for human brain research. However, conventional brain PET typically requires subjects to remain stationary in a sitting or supine position during scanning. This study evaluated the performance of SmartBrain, a wearable brain PET system for real-time imaging. Methods: SmartBrain uses 192 detectors, with each detector consisting of a 6 × 6 lutetium-yttrium oxyorthosilicate crystal (3 × 3 × 5 mm³) array with a 3 × 3 silicon photomultiplier array. We evaluated the physical performance of SmartBrain in accordance with 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 multilayer Derenzo phantom. Dynamic rat images and the ¹⁸F-FDG images from a healthy volunteer are presented. Results: Spatial resolution is 2.29 mm in the center of the field of view. The sensitivity was 720.2 cps/MBq. The peak noise-equivalent count rate was 4.67 kcps at 10.1 kBq/mL, and the scatter fraction was 29.5%. The NEMA image-quality contrast recovery coefficients ranged from 72.9% (10-mm sphere) to 89.4% (37-mm sphere), and background variability was 11.3% at a contrast ratio of 9.4:1. The time-of-flight resolution was 234 ps, and the energy resolution was 10.8%. SmartBrain showed that the main structures of the custom Hoffman brain phantom could be resolved and demonstrated the ability to separate rods as small as 1.7 mm. Conclusion: 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 neurologic disorders.