Document Detail

Attenuation correction methods suitable for brain imaging with a PET/MRI scanner: a comparison of tissue atlas and template attenuation map approaches.
MedLine Citation:
PMID:  21724984     Owner:  NLM     Status:  MEDLINE    
METHODS: Two MRI and attenuation map pairs were evaluated: tissue atlas-based and measured templates. The tissue atlas approach used a composite of the BrainWeb and Zubal digital phantoms, whereas the measured templates were produced by averaging spatially normalized measured MR image and coregistered attenuation maps. The composite digital phantom was manually edited to include 2 additional tissue classes (paranasal sinuses, and ethmoidal air cells or nasal cavity). In addition, 3 attenuation values for bone were compared. The MRI and attenuation map pairs were used to generate subject-specific attenuation maps via nonrigid registration of the MRI to the MR image of the subject. SPM2 and a B-spline free-form deformation algorithm were used for the nonrigid registration. To determine the accuracy of the modeled AC approaches, radioactivity concentration was assessed on a voxelwise and regional basis.
RESULTS: The template approach produced better spatial consistency than the phantom-based atlas, with an average percentage error in radioactivity concentration across the regions, compared with measured AC, of -1.2% ± 1.2% and -1.5% ± 1.9% for B-spline and SPM2 registration, respectively. In comparison, the tissue atlas method with B-spline registration produced average percentage errors of 0.0% ± 3.0%, 0.9% ± 2.9%, and 2.9% ± 2.8% for bone attenuation values of 0.143 cm(-1), 0.152 cm(-1), and 0.172 cm(-1), respectively. The largest errors for the template AC method were found in parts of the frontal cortex (-3%) and the cerebellar vermis (-5%). Intersubject variability was higher with SPM2 than with B-spline. Compared with measured AC, template AC with B-spline and SPM2 achieved a correlation coefficient (R(2)) of 0.99 and 0.98, respectively, for regional radioactivity concentration. The corresponding R(2) for the tissue atlas approach with B-spline registration was 0.98, irrespective of the bone attenuation coefficient.
CONCLUSION: Nonrigid registration of joint MRI and attenuation map templates can produce accurate AC for brain PET scans, particularly with measured templates and B-spline registration. Consequently, these methods are suitable for AC of brain scans acquired on combined PET/MRI systems.
Ian B Malone; Richard E Ansorge; Guy B Williams; Peter J Nestor; T Adrian Carpenter; Tim D Fryer
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of nuclear medicine : official publication, Society of Nuclear Medicine     Volume:  52     ISSN:  1535-5667     ISO Abbreviation:  J. Nucl. Med.     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-07-04     Completed Date:  2011-09-05     Revised Date:  2014-02-20    
Medline Journal Info:
Nlm Unique ID:  0217410     Medline TA:  J Nucl Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1142-9     Citation Subset:  IM    
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MeSH Terms
Brain / cytology*,  radionuclide imaging*
Fluorodeoxyglucose F18 / diagnostic use
Image Processing, Computer-Assisted / methods*
Magnetic Resonance Imaging / methods*
Models, Biological
Positron-Emission Tomography / methods*
Grant Support
G108/653//Medical Research Council; G9724461//Medical Research Council
Reg. No./Substance:
0Z5B2CJX4D/Fluorodeoxyglucose F18

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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