PET brain imaging of awake small animals
17 April 2019
NEW LOCATION - UAntwerp - Campus Drie Eiken - Building R - R.008 - Universiteitsplein 1 - 2610 WILRIJK (route: UAntwerpen, Campus Drie Eiken
Alan Miranda Menchaca
Prof J. Verhaeghe, Prof S. Staelens
PhD defence Alan Miranda Menchaca - Faculty of Medicine and Health Sciences (in English)
Summary (Presentation in English)
Preclinical positron emission tomography (PET) for rodents is performed under anesthesia to immobilize the animal and to avoid motion artifacts in the reconstruction image. However, the use of anesthesia can alter the normal physiological processes of the animal. For this reason, it is desired to perform the PET scans without the use of anesthesia. PET scans of awake animals can also be relevant in the study of neuropsychiatric conditions such as schizophrenia, substance abuse and depression, in which brain function in the awake state can be different from brain function under anesthesia.
Particularly for brain PET imaging, awake scans of rats can be performed by tracking the head of the animal during the PET scan and correcting the tomographic data using the tracking information. This approach was further developed in this thesis proposing several tracking methods with the main focus on practical feasibility and minimizing animal discomfort.
Two different optical tracking methods and a methods specific for PET imaging were implemented. Motion tracking of the rat head was first investigated using a checkerboard marker-based camera in a preclinical scanner. A second method investigated used a markerless infra-red stereo camera to track the motion of the rat head without physical markers. A method which requires no optical tracking cameras was developed next; radioactive point sources are used as markers attached to the animal head to track its motion. These point sources are small and light so to not disturb the animal. The use of external hardware was avoided using this method. The point source tracking method was also implemented for awake mice brain scans in a preclinical scanner and for brain scans of interacting rats in a large field of view human brain scanner.
The methods developed in this thesis allow PET brain scanning of small animals without the confounding factor of anesthesia. In addition to that, particularly for the case of the point source tracking method, animal behavior information can be acquired in free running mice and interacting rats. Experimental setups where the animal need to be in awake state, e.g. to measure its response to external stimuli, can also be designed using the methods developed here. The point source tracking method also shows promise in PET brain clinical imaging, where it can be used for motion tracking of human head motion.
Contact email: Nicolaas.VanLeeuwen@uantwerpen.be