Improved quantitation and reproducibility in multi-PET/CT lung studies by combining CT information

Abstract Background Matched attenuation maps are vital for obtaining accurate and reproducible kinetic and static parameter estimates from PET data. With increased interest in PET/CT imaging of diffuse lung diseases for assessing disease progression and treatment effectiveness, understanding the ext...

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Main Authors: Beverley F. Holman, Vesna Cuplov, Lynn Millner, Raymond Endozo, Toby M. Maher, Ashley M. Groves, Brian F. Hutton, Kris Thielemans
Format: Article
Language:English
Published: SpringerOpen 2018-06-01
Series:EJNMMI Physics
Subjects:
Online Access:http://link.springer.com/article/10.1186/s40658-018-0212-0
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spelling doaj-cfa497e801a54e1f949edd835087ca322020-11-25T00:11:29ZengSpringerOpenEJNMMI Physics2197-73642018-06-015111410.1186/s40658-018-0212-0Improved quantitation and reproducibility in multi-PET/CT lung studies by combining CT informationBeverley F. Holman0Vesna Cuplov1Lynn Millner2Raymond Endozo3Toby M. Maher4Ashley M. Groves5Brian F. Hutton6Kris Thielemans7Institute of Nuclear Medicine, University College LondonInstitute of Nuclear Medicine, University College LondonInstitute of Nuclear Medicine, University College LondonInstitute of Nuclear Medicine, University College LondonNational Institute for Health Research Respiratory Biomedical Research Unit, Royal Brompton HospitalInstitute of Nuclear Medicine, University College LondonInstitute of Nuclear Medicine, University College LondonInstitute of Nuclear Medicine, University College LondonAbstract Background Matched attenuation maps are vital for obtaining accurate and reproducible kinetic and static parameter estimates from PET data. With increased interest in PET/CT imaging of diffuse lung diseases for assessing disease progression and treatment effectiveness, understanding the extent of the effect of respiratory motion and establishing methods for correction are becoming more important. In a previous study, we have shown that using the wrong attenuation map leads to large errors due to density mismatches in the lung, especially in dynamic PET scans. Here, we extend this work to the case where the study is sub-divided into several scans, e.g. for patient comfort, each with its own CT (cine-CT and ‘snap shot’ CT). A method to combine multi-CT information into a combined-CT has then been developed, which averages the CT information from each study section to produce composite CT images with the lung density more representative of that in the PET data. This combined-CT was applied to nine patients with idiopathic pulmonary fibrosis, imaged with dynamic 18F-FDG PET/CT to determine the improvement in the precision of the parameter estimates. Results Using XCAT simulations, errors in the influx rate constant were found to be as high as 60% in multi-PET/CT studies. Analysis of patient data identified displacements between study sections in the time activity curves, which led to an average standard error in the estimates of the influx rate constant of 53% with conventional methods. This reduced to within 5% after use of combined-CTs for attenuation correction of the study sections. Conclusions Use of combined-CTs to reconstruct the sections of a multi-PET/CT study, as opposed to using the individually acquired CTs at each study stage, produces more precise parameter estimates and may improve discrimination between diseased and normal lung.http://link.springer.com/article/10.1186/s40658-018-0212-0LungDensityPET/CTRespirationAttenuation correctionQuantitation
collection DOAJ
language English
format Article
sources DOAJ
author Beverley F. Holman
Vesna Cuplov
Lynn Millner
Raymond Endozo
Toby M. Maher
Ashley M. Groves
Brian F. Hutton
Kris Thielemans
spellingShingle Beverley F. Holman
Vesna Cuplov
Lynn Millner
Raymond Endozo
Toby M. Maher
Ashley M. Groves
Brian F. Hutton
Kris Thielemans
Improved quantitation and reproducibility in multi-PET/CT lung studies by combining CT information
EJNMMI Physics
Lung
Density
PET/CT
Respiration
Attenuation correction
Quantitation
author_facet Beverley F. Holman
Vesna Cuplov
Lynn Millner
Raymond Endozo
Toby M. Maher
Ashley M. Groves
Brian F. Hutton
Kris Thielemans
author_sort Beverley F. Holman
title Improved quantitation and reproducibility in multi-PET/CT lung studies by combining CT information
title_short Improved quantitation and reproducibility in multi-PET/CT lung studies by combining CT information
title_full Improved quantitation and reproducibility in multi-PET/CT lung studies by combining CT information
title_fullStr Improved quantitation and reproducibility in multi-PET/CT lung studies by combining CT information
title_full_unstemmed Improved quantitation and reproducibility in multi-PET/CT lung studies by combining CT information
title_sort improved quantitation and reproducibility in multi-pet/ct lung studies by combining ct information
publisher SpringerOpen
series EJNMMI Physics
issn 2197-7364
publishDate 2018-06-01
description Abstract Background Matched attenuation maps are vital for obtaining accurate and reproducible kinetic and static parameter estimates from PET data. With increased interest in PET/CT imaging of diffuse lung diseases for assessing disease progression and treatment effectiveness, understanding the extent of the effect of respiratory motion and establishing methods for correction are becoming more important. In a previous study, we have shown that using the wrong attenuation map leads to large errors due to density mismatches in the lung, especially in dynamic PET scans. Here, we extend this work to the case where the study is sub-divided into several scans, e.g. for patient comfort, each with its own CT (cine-CT and ‘snap shot’ CT). A method to combine multi-CT information into a combined-CT has then been developed, which averages the CT information from each study section to produce composite CT images with the lung density more representative of that in the PET data. This combined-CT was applied to nine patients with idiopathic pulmonary fibrosis, imaged with dynamic 18F-FDG PET/CT to determine the improvement in the precision of the parameter estimates. Results Using XCAT simulations, errors in the influx rate constant were found to be as high as 60% in multi-PET/CT studies. Analysis of patient data identified displacements between study sections in the time activity curves, which led to an average standard error in the estimates of the influx rate constant of 53% with conventional methods. This reduced to within 5% after use of combined-CTs for attenuation correction of the study sections. Conclusions Use of combined-CTs to reconstruct the sections of a multi-PET/CT study, as opposed to using the individually acquired CTs at each study stage, produces more precise parameter estimates and may improve discrimination between diseased and normal lung.
topic Lung
Density
PET/CT
Respiration
Attenuation correction
Quantitation
url http://link.springer.com/article/10.1186/s40658-018-0212-0
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