Quantitative Bayesian model-based analysis of amide proton transfer MRI.
Amide Proton Transfer (APT) reports on contrast derived from the exchange of protons between amide groups and water. Commonly, APT contrast is quantified by asymmetry analysis, providing an ensemble contrast of both amide proton concentration and exchange rate. An alternative is to sample the off-re...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Journal article |
| Sprog: | English |
| Udgivet: |
2013
|
| _version_ | 1826300234581409792 |
|---|---|
| author | Chappell, M Donahue, M Tee, Y Khrapitchev, A Sibson, N Jezzard, P Payne, S |
| author_facet | Chappell, M Donahue, M Tee, Y Khrapitchev, A Sibson, N Jezzard, P Payne, S |
| author_sort | Chappell, M |
| collection | OXFORD |
| description | Amide Proton Transfer (APT) reports on contrast derived from the exchange of protons between amide groups and water. Commonly, APT contrast is quantified by asymmetry analysis, providing an ensemble contrast of both amide proton concentration and exchange rate. An alternative is to sample the off-resonant spectrum and fit an exchange model, permitting the APT effect to be quantified, correcting automatically for confounding effects of spillover, field inhomogeneity, and magnetization transfer. Additionally, it should permit amide concentration and exchange rate to be independently quantified. Here, a Bayesian method is applied to this problem allowing pertinent prior information to be specified. A three-pool model was used incorporating water protons, amide protons, and magnetization transfer effect. The method is demonstrated in simulations, creatine phantoms with varying pH and in vivo (n = 7). The Bayesian model-based approach was able to quantify the APT effect accurately (root-mean-square error < 2%) even when subject to confounding field variation and magnetization transfer effect, unlike traditional asymmetry analysis. The in vivo results gave approximate APT concentration (relative to water) and exchange rate values of 3 × 10(-3) and 15 s(-1) . A degree of correlation was observed between these parameter making the latter difficult to quantify with absolute accuracy, suggesting that more optimal sampling strategies might be required. |
| first_indexed | 2024-03-07T05:14:04Z |
| format | Journal article |
| id | oxford-uuid:dc8e2fae-bbe3-4046-a8c6-0903c04f4d27 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T05:14:04Z |
| publishDate | 2013 |
| record_format | dspace |
| spelling | oxford-uuid:dc8e2fae-bbe3-4046-a8c6-0903c04f4d272022-03-27T09:18:34ZQuantitative Bayesian model-based analysis of amide proton transfer MRI.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:dc8e2fae-bbe3-4046-a8c6-0903c04f4d27EnglishSymplectic Elements at Oxford2013Chappell, MDonahue, MTee, YKhrapitchev, ASibson, NJezzard, PPayne, SAmide Proton Transfer (APT) reports on contrast derived from the exchange of protons between amide groups and water. Commonly, APT contrast is quantified by asymmetry analysis, providing an ensemble contrast of both amide proton concentration and exchange rate. An alternative is to sample the off-resonant spectrum and fit an exchange model, permitting the APT effect to be quantified, correcting automatically for confounding effects of spillover, field inhomogeneity, and magnetization transfer. Additionally, it should permit amide concentration and exchange rate to be independently quantified. Here, a Bayesian method is applied to this problem allowing pertinent prior information to be specified. A three-pool model was used incorporating water protons, amide protons, and magnetization transfer effect. The method is demonstrated in simulations, creatine phantoms with varying pH and in vivo (n = 7). The Bayesian model-based approach was able to quantify the APT effect accurately (root-mean-square error < 2%) even when subject to confounding field variation and magnetization transfer effect, unlike traditional asymmetry analysis. The in vivo results gave approximate APT concentration (relative to water) and exchange rate values of 3 × 10(-3) and 15 s(-1) . A degree of correlation was observed between these parameter making the latter difficult to quantify with absolute accuracy, suggesting that more optimal sampling strategies might be required. |
| spellingShingle | Chappell, M Donahue, M Tee, Y Khrapitchev, A Sibson, N Jezzard, P Payne, S Quantitative Bayesian model-based analysis of amide proton transfer MRI. |
| title | Quantitative Bayesian model-based analysis of amide proton transfer MRI. |
| title_full | Quantitative Bayesian model-based analysis of amide proton transfer MRI. |
| title_fullStr | Quantitative Bayesian model-based analysis of amide proton transfer MRI. |
| title_full_unstemmed | Quantitative Bayesian model-based analysis of amide proton transfer MRI. |
| title_short | Quantitative Bayesian model-based analysis of amide proton transfer MRI. |
| title_sort | quantitative bayesian model based analysis of amide proton transfer mri |
| work_keys_str_mv | AT chappellm quantitativebayesianmodelbasedanalysisofamideprotontransfermri AT donahuem quantitativebayesianmodelbasedanalysisofamideprotontransfermri AT teey quantitativebayesianmodelbasedanalysisofamideprotontransfermri AT khrapitcheva quantitativebayesianmodelbasedanalysisofamideprotontransfermri AT sibsonn quantitativebayesianmodelbasedanalysisofamideprotontransfermri AT jezzardp quantitativebayesianmodelbasedanalysisofamideprotontransfermri AT paynes quantitativebayesianmodelbasedanalysisofamideprotontransfermri |