Speaker
Description
PET is an ideal imaging modality for studying human brain biochemistry in vivo, but its potential is limited by its poor spatial resolution, which is currently well below the theoretical limit. The brain-dedicated UHR scanner is designed to achieve 2 µL volumetric resolution for accurate characterization of brain regions previously indistinguishable without MRI. Unlike most PET systems, the UHR relies on fully pixelated detectors with 1:1:1 coupling of the scintillation crystal, photodetector, and electronic readout to avoid degradation caused by light/charge sharing schemes. UHR physical performance was characterized using NEMA NU4-2008/NU2-2018 standards, while imaging performance was evaluated using phantoms and pilot studies in patients undergoing medically prescribed 18F-FDG scans. Point source OSEM reconstruction yields resolution better than 2 µL (<1.25 mm quasi-isotropic) up to ~3.5 cm from FOV center and remains below 2 mm radially up to ~7 cm. This is confirmed in images of hot spot phantoms in which 1.2 (1.6) mm hot spots can be resolved up to 5 (10) cm from center. Sensitivity, count rates and contrast recovery were also measured. In patients, small deep brain regions are visually delineated, particularly in the thalamus and brainstem, while hypermetabolic areas are visible along the cortical surface and regions of the subcortical anatomy rarely seen as separate entities, such as subthalamic and brainstem nuclei, which can now be better quantified in UHR images.
| Field | Systems and applications |
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