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MRI-Based Attenuation Correction for PET/MRI: A Novel Approach Combining Pattern Recognition and Atlas Registration

2008

Article

ei


For quantitative PET information, correction of tissue photon attenuation is mandatory. Generally in conventional PET, the attenuation map is obtained from a transmission scan, which uses a rotating radionuclide source, or from the CT scan in a combined PET/CT scanner. In the case of PET/MRI scanners currently under development, insufficient space for the rotating source exists; the attenuation map can be calculated from the MR image instead. This task is challenging because MR intensities correlate with proton densities and tissue-relaxation properties, rather than with attenuation-related mass density. METHODS: We used a combination of local pattern recognition and atlas registration, which captures global variation of anatomy, to predict pseudo-CT images from a given MR image. These pseudo-CT images were then used for attenuation correction, as the process would be performed in a PET/CT scanner. RESULTS: For human brain scans, we show on a database of 17 MR/CT image pairs that our method reliably enables e stimation of a pseudo-CT image from the MR image alone. On additional datasets of MRI/PET/CT triplets of human brain scans, we compare MRI-based attenuation correction with CT-based correction. Our approach enables PET quantification with a mean error of 3.2% for predefined regions of interest, which we found to be clinically not significant. However, our method is not specific to brain imaging, and we show promising initial results on 1 whole-body animal dataset. CONCLUSION: This method allows reliable MRI-based attenuation correction for human brain scans. Further work is necessary to validate the method for whole-body imaging.

Author(s): Hofmann, M. and Steinke, F. and Scheel, V. and Charpiat, G. and Farquhar, J. and Aschoff, P. and Brady, M. and Schölkopf, B. and Pichler, BJ.
Journal: Journal of Nuclear Medicine
Volume: 49
Number (issue): 11
Pages: 1875-1883
Year: 2008
Month: October
Day: 0

Department(s): Empirical Inference
Research Project(s): Medical and Neuroscientific Imaging
Bibtex Type: Article (article)

Digital: 0
DOI: 10.2967/jnumed.107.049353
Language: en
Organization: Max-Planck-Gesellschaft
School: Biologische Kybernetik

Links: Web

BibTex

@article{5592,
  title = {MRI-Based Attenuation Correction for PET/MRI: A Novel Approach Combining Pattern Recognition and Atlas Registration},
  author = {Hofmann, M. and Steinke, F. and Scheel, V. and Charpiat, G. and Farquhar, J. and Aschoff, P. and Brady, M. and Sch{\"o}lkopf, B. and Pichler, BJ.},
  journal = {Journal of Nuclear Medicine},
  volume = {49},
  number = {11},
  pages = {1875-1883},
  organization = {Max-Planck-Gesellschaft},
  school = {Biologische Kybernetik},
  month = oct,
  year = {2008},
  month_numeric = {10}
}