Abstract
Objectives
To implement and evaluate a dedicated receiver array coil for simultaneous positron emission tomography/magnetic resonance (PET/MR) imaging in breast cancer.
Methods
A 16-channel receiver coil design was optimized for simultaneous PET/MR imaging. To assess MR performance, the signal-to-noise ratio, parallel imaging capability and image quality was evaluated in phantoms, volunteers and patients and compared to clinical standard protocols. For PET evaluation, quantitative 18 F-FDG PET images of phantoms and seven patients (14 lesions) were compared to images without the coil. In PET image reconstruction, a CT-based template of the coil was combined with the MR-acquired attenuation correction (AC) map of the phantom/patient.
Results
MR image quality was comparable to clinical MR-only examinations. PET evaluation in phantoms showed regionally varying underestimation of the standardised uptake value (SUV; mean 22 %) due to attenuation caused by the coil. This was improved by implementing the CT-based coil template in the AC (<2 % SUV underestimation). Patient data indicated that including the coil in the AC increased the SUV values in the lesions (21 ± 9 %).
Conclusions
Using a dedicated PET/MR breast coil, state-of-the-art MRI was possible. In PET, accurate quantification and image homogeneity could be achieved if a CT-template of this coil was included in the AC for PET image reconstruction.
Key Points
• State-of-the-art breast MRI using a dedicated PET/MR breast coil is feasible.
• A multi-channel design facilitates shorter MR acquisition times via parallel imaging.
• An MR coil inside a simultaneous PET/MR system causes PET photon attenuation.
• Including a coil CT-template in PET image reconstruction results in recovering accurate quantification.
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Acknowledgments
We gratefully acknowledge the excellent technical assistance of Sylvia Schachoff, Anna Winter and Claudia Meisinger (all TU München). We thank Rebekka Kraus (TU München), Christine Dörnfeld (Uni-Klinik Würzburg) and Siemens Healthcare for fruitful discussions.
This study has received funding by the ”Bundesministerium für Wirtschaft und Technologie (BMWi)“ (German Ministry of Economics and Technology, ZIM-Kooperationsprojekte KF2922301RR1). The PET/MR system used for this study was funded through the “Deutsche Forschungsgemeinschaft (DFG) Grossgeräteinitiative 2010.” This work was supported in part by a research grant from Siemens Healthcare.
The scientific guarantor of this publication is Prof. Dr. med Schwaiger. The authors of this manuscript declare relationships with the following companies: Rapid Biomedical GmbH, Rimpar, Germany and Siemens Healthcare, Erlangen, Germany. No complex statistical methods were necessary for this paper. Institutional Review Board approval was obtained. Written informed consent was obtained from all subjects (patients) in this study. Methodology: Prospective, experimental, performed at one institution.
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Stephan G. Nekolla and Markus Schwaiger contributed equally
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Dregely, I., Lanz, T., Metz, S. et al. A 16-channel MR coil for simultaneous PET/MR imaging in breast cancer. Eur Radiol 25, 1154–1161 (2015). https://doi.org/10.1007/s00330-014-3445-x
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DOI: https://doi.org/10.1007/s00330-014-3445-x