Medical Imaging Physics (INM-4)

TECHNICAL ASPECTS OF MR-PET

The hybrid scanner 3T MR-PET consists of a high-resolution BrainPET, newly constructed by Siemens, and a commercial 3T MAGNETOM Trio MRI scanner. The 9.4TMR-PET combines the BrainPET with a 9.4TMRI developed through collaboration between the Forschungszentrum Jülich and Siemens.

The BrainPET is a compact cylinder with a length of 72 cm and an outer diameter of 60 cm, fitting snugly into the bore of the magnet. Within its inner diameter of 32 cm, there is a birdcage head coil used for both transmitting radiofrequency pulses and receiving the signals and an inner 8-channel coil for receive only.

The BrainPET consists of 32 copper shielded cassettes, each containing six detector modules covering an axial field-of-view (FOV) of 19.2 cm. The front end of the detector module is a 12 x 12 matrix of 2.5 x 2.5 x 20 mm3 individual LSO (Lutetium oxysilicate)scintillation crystals coupled to a 3 x 3 array of avalanche photodiodes (APD).

The APD are not influenced by the magnetic field and are used instead of photomultipliers which would not work in the MR environment. Since the APDs are temperature sensitive, the temperature of the BrainPET is stabilised with cooled air. The APD output signals are preamplified and transferred via long cables to the filter plate and thereafter to the data acquisition electronics. Here the coincidence lines are recorded so that PET images can be reconstructed as decribed at ( Technical Aspects of Positron-Emission-Tomography). The BrainPET offers an excellent image resolution of 3 mm at the centre.

Projects

BrainPET-7T

The objective of the BrainPET-7T project is to build a new generation, UHF-MRI compatible, advanced PET insert for the dedicated purpose of neuroimaging, which may be licensed to a corporation for market launch when the project has been completed.

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Attenuation Correction for MR-PET

The combination of Positron Emission Tomography (PET) with magnetic resonance imaging (MRI) in hybrid MR-PET scanners offers a number of advantages when investigating brain structure and function.

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The objective of the BrainPET-7T project is to build a new generation, UHF-MRI compatible, advanced PET insert for the dedicated purpose of neuroimaging, which may be licensed to a corporation for market launch when the project has been completed.

More

Quantitative PET imaging with MR-PET

PET images are, however, not only expected to be of high quality, but should produce quantitative data of metabolic functions. To achieve this aim we developed and implemented methods to quantify the PET images that are acquired simultaneously with MRI.

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Development of iterativer reconstruction methods

PET images reconstructed by iterative methods such as the maximum likelihood expectation maximisation (MLEM) or ordered subset expectation maximisation (OSEM) algorithms exhibit a favourable signal-to-noise ratio compared to results of filtered back projection, especially in the case of studies with low counts.

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PET images are, however, not only expected to be of high quality, but should produce quantitative data of metabolic functions. To achieve this aim we developed and implemented methods to quantify the PET images that are acquired simultaneously with MRI.

More

Development and optimisation of MR-PET applications

Dynamic PET studies such as those performed in brain tumour patients after injection of [18F]-Fluor-Ethyl-Tyrosine (FET) last for 50 minutes. During this period a number of MR sequences can be performed.

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Dynamic PET studies such as those performed in brain tumour patients after injection of [18F]-Fluor-Ethyl-Tyrosine (FET) last for 50 minutes. During this period a number of MR sequences can be performed.

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GROUP LEADER

Univ.-Prof. Dr. Dr. h.c. N. J. Shah

Institute Director INM-4

• Institute of Neurosciences and Medicine (INM)
• Medical Imaging Physics (INM-4)

Building 15.14 /
Room 201

+49 2461/61-6836

E-Mail

Dr. Christoph Lerche

• Institute of Neurosciences and Medicine (INM)
• Medical Imaging Physics (INM-4)

Building 15.2v /
Room 310

+49 2461/61-96524

E-Mail

Prof. Dr. Irene Neuner

• Institute of Neurosciences and Medicine (INM)
• Medical Imaging Physics (INM-4)

Building 15.14 /
Room 211

+49 2461/61-6356

E-Mail

Staff

Silke FrenschBuilding 15.2 / Room R 246+49 2461/61-6058

Dr. Jürgen ScheinsBuilding 15.9 / Room R 2011+49 2461/61-2740