Performance test of an LSO-APD detector in a 7-T MRI scanner for simultaneous PET/MRI.
PET combined with CT has proven to be a valuable multimodality imaging device revealing both functional and anatomic information. Although PET/CT has become completely integrated into routine clinical application and also has been used in small-animal imaging, CT provides only limited soft-tissue contrast and, in preclinical studies, exposes the animal to a relatively high radiation dose. Unlike CT, MRI provides good soft-tissue contrast even without application of contrast agents and, furthermore, does not require ionizing radiation.


METHODS
This project focused on combining a high-resolution PET scanner with a 7-T MRI system for animal research. Because classic PET detectors based on photomultiplier tubes cannot be used in high magnetic fields, we used a detector technology based on 10 x 10 lutetium oxyorthosilicate crystal arrays and 3 x 3 avalanche photodiode arrays. A ring of such PET detectors will ultimately be used as an insert for the 119-mm-diameter MRI bore.


RESULTS
Initial measurements with 1 PET detector module in the 7-T field during application of MRI sequences were encouraging. Position profiles from the PET detectors and a first MR image of a mouse could be acquired simultaneously.


CONCLUSIONS
Further work will concentrate on the construction of a full PET detector ring with compact, integrated electronics.
Pichler
Bernd J
BJ
Department of Biomedical Engineering, University of California, Davis, USA. Bernd.Pichler@med.uni-tuebingen.de
Judenhofer
Martin S
MS
Catana
Ciprian
C
Walton
Jeffrey H
JH
Kneilling
Manfred
M
Nutt
Robert E
RE
Siegel
Stefan B
SB
Claussen
Claus D
CD
Cherry
Simon R
SR
D000818:Animals; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D051379:Mice; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation* / Q000379:methods