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The world's first PET-MRI with two high-end PET and MRI
- Ultra-high resolution HRRT-PET and ultra-high field 7.0T MRI

PET and MRI are the most widely used imaging tools in clinical and neuroscience research. PET an unique device which can perform in vivo neurochemical imaging, such as the glucose consumption, distribution of neurotransmitters and their bindings, and blood flow within the brain tissue. On the other hand, MRI has the capability of imaging anatomical structures to a high spatial resolution with various tissue contrasts like T1-weighted, T2-weighted, and proton-density imaging, diffusion imaging, flow-related imaging, and functional imaging. These imaging technologies, however, have physical limitations. PET has poor spatial resolution in comparison to MRI, while MRI lacks the capability to image biochemical changes. In order to overcome these limitations, the combination of PET images with MRI represents the best solution, especially in the field of neurological imaging. However, a major obstacle in developing a fusion PET/MRI system is that the PET is an instrument extremely sensitive to magnetic field thus it is not permitted to couple to or even can not be placed near the MRI, especially such as 7.0T MRI. In order to avoid this interference and to fully utilize the imaging capability of high resolution PET and ultra-high field MRI in human imaging, we have developed the HRRT-PET/7.0T MRI hybrid system, operating each scanner separately and connecting the two using a high precision mechanical shuttle bed. This configuration shares many characteristics with the current PET/CT configuration. These two high end PET (HRRT-PET) and 7.0T MRI provide unprecedented high resolution molecular of neurochemical information hitherto unavailable by any other techniques.

As shown in the figure, PET and MRI are installed as closely as possible. The two are connected by a shuttle system composed of a bed and its guiding rails. Proper magnetic and RF shielding was designed for the PET side and the shuttle bed to avoid interference from the strong magnetic fields generated by the 7.0T MRI. The shuttle system was designed to fulfill a mechanical precision of less than 0.05 mm and it is capable of operating under a high magnetic field. This mechanical precision is sufficient for the spatial resolution of the 7.0T MRI so that the HRRT-PET images can precisely be guided into the desired neuro-anatomical regions. The major advantage of this type of PET/MRI system is that it allows the exploitation of the best qualities of both systems, preserving the available resolution and sensitivity of HRRT-PET and ultra-high field 7.0T MRI without any compromise or interference. Images shown above demonstrate how image fusion could provide sub-hippocampal metabolic functions precisely indicated by the anatomical landmarks such as CA4 and subiculum shown in the right at 7.0T MRI.

Link to PET-MRI Fusion System Research