PET/MR-Physics: High-resolution tomographs
High-resolution PET
For the precise identification of brain structures we use positron-emission-tomographs with as high as possible spatial resolution. CTI (now Siemens Medical Solutions, Knoxville, USA) developed the EXACT HR and the HRRT PET-tomograph in cooperation with the MPI for neurological research.
- EXACT HR (HR: High Resolution)
The EXACT HR achieves the highest resolution of all commercial clinical PET-scanners with BGO block detectors. - HRRT (HRRT: High Resolution Research Tomograph)
With the new detector material LSO the individual crystals can be made smaller. This improved the spatial resolution of the research tomograph HRRT to better than 2.5 mm. In addition the resolution is almost isotropic in a 20 cm diameter volume because of the phoswich design of the block detectors. - microPET
With the new detector material LSO the individual crystals can be made smaller. This improved the spatial resolution of the research tomograph HRRT The microPET-scanner achieves an even better resolution of less than 2 mm. This scanner has a considerably smaller diameter of the detector rings resulting in a better resolution in comparison to clinical tomographs. The microPET was purpose-built for PET studies with small animals by Concorde Microsystems (now Siemens Preclinical Solutions, Knoxville, USA). This tomograph is equipped with LSO block detectors similar to those of the HRRT.
- Der Colliculus inferior, links im MR-Bild, ist auch rechts im FDG PET-Bild des HRRT deutlich mit erhöhtem Glucosestoffwechsel sichtbar. Wegen seiner geringen Größe kann der Colliculus inferior mit Tomographen mit niedrigerer Auflösung nicht klar dargestellt werden.
MR/PET
The MR/PET-system is a clinical tomograph, which will allow us to study the human brain with high sensitivity simultaneously with PET and MR.
This combi-tomograph is a MAGNETOM Trio-tomograph with a PET-insert mounted in the center of the gantry. The MR-part is already being used, the PET-insert will be installed soon.
The PET-insert is equipped with avalanche photodiodes, made from silicon, instead of conventional photomultiplier-tubes. The PET-detector-rings are mounted around the MR-headcoil inside the 60 cm wide opening of the TRIO. This allows the simultaneous operation of PET-detector-rings inside the 3 Tesla magnetic field of the MR-scanner. The PET-insert can be removed easily for separate operation of the MR-scanner.
The simultaneous measuring of MRI- and PET-parameters opens up a variety of unique new research methods for dynamic, time-critical processes. For example we can
- clarify differences in localisation, spatial extent and time response of the image information in both imaging modalities
- directly compare activations in functional MR-tomography with activations of neuroreceptor- and neurotransmitter-systems in PET
- and in addition: There is no longer the need to coregister the morphological MR images with PET images
Siemens Medical Solutions, Knoxville, USA, cooperates with us in the development of the PET insert.
The PET-Scanners of the Institute:
- ECAT EXACT HR
- ECAT HRRT
- microPET R4
- MR/PET (im Aufbau)
The HRRT (High Resolution Research Tomograph) with open gantry. The eight detector heads with highly integrated electronics are arranged in an octagon.
The MAGNETOM Trio MR-Tomograph, the PET-insert is still missing