Title :
Analysis and Correction of Count Rate Reduction During Simultaneous MR-PET Measurements With the BrainPET Scanner
Author :
Weirich, Christoph ; Brenner, Daniel ; Scheins, Jürgen ; Besançon, Étienne ; Tellmann, Lutz ; Herzog, Hans ; Shah, N. Jon
Author_Institution :
Inst. of Neurosci. & Med., Forschungszentrum Julich GmbH, Jülich, Germany
fDate :
7/1/2012 12:00:00 AM
Abstract :
In hybrid magnetic resonance-positron emission tomography (MR-PET) studies with the Siemens 3T MR-BrainPET scanner an instantaneous reduction of the PET sensitivity was observed during execution of certain MR sequences. This interference was investigated in detail with custom-made as well as standard clinical MR sequences. The radio-frequency pulses, the switched gradient fields and the constant magnetic field were examined as the relevant parameters of the magnetic resonance imaging (MRI) system as well as the air temperature within the PET detectors. Our investigation comprised the analysis of the analog PET signals, the total count rates, the geometric distribution of the count rate reduction within the BrainPET detector as well as reconstructed images. The fast switching magnetic field gradients were identified to distort the analog PET detector signals. The measured count rate reduction was found to be less than 3%, but only up to 2% in the case of echo planar imaging sequences, as applied in functional MRI. For clinical sequences routinely used in hybrid MR-BrainPET measurements, a correction method has been designed, implemented, and evaluated .
Keywords :
biomedical MRI; biomedical measurement; brain; image reconstruction; image sequences; magnetic switching; medical image processing; neurophysiology; positron emission tomography; PET detectors; PET sensitivity; air temperature; analog PET detector signals; analog PET signals; constant magnetic field; correction method; count rate reduction; echo planar imaging sequences; fast switching magnetic field gradients; geometric distribution; hybrid magnetic resonance-positron emission tomography; image reconstruction; magnetic resonance imaging system; radiofrequency pulses; siemens 3T MR-brainPET scanner; simultaneous MR-PET measurements; standard clinical MR sequences; switched gradient fields; Detectors; Magnetic field measurement; Magnetic fields; Magnetic resonance imaging; Positron emission tomography; Radio frequency; Temperature measurement; Correction; count rate reduction; magnetic resonance imaging (MRI); mutual interference; positron emission tomography (PET); Brain; Electromagnetic Fields; Electronics, Medical; Equipment Failure Analysis; Humans; Magnetic Resonance Imaging; Positron-Emission Tomography; Radio Waves; Reproducibility of Results;
Journal_Title :
Medical Imaging, IEEE Transactions on
DOI :
10.1109/TMI.2012.2188903