Optimizing T2 Quantitative Estimation of Knee Cartilage with Magnetic Resonance Imaging Applying Dictionary-based Methods

Detalhes bibliográficos
Autor(a) principal: Nunes, Ângelo Trindade
Data de Publicação: 2021
Tipo de documento: Dissertação
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10451/53671
Resumo: Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Engenharia Clínica e Instrumentação Médica) Universidade de Lisboa, Faculdade de Ciências, 2022
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spelling Optimizing T2 Quantitative Estimation of Knee Cartilage with Magnetic Resonance Imaging Applying Dictionary-based MethodsMapas T2Imagem por Ressonância MagnéticaMétodo do DicionárioOsteoartriteSequência Multi-Spin-EchoTeses de mestrado - 2022Departamento de FísicaTese de mestrado integrado, Engenharia Biomédica e Biofísica (Engenharia Clínica e Instrumentação Médica) Universidade de Lisboa, Faculdade de Ciências, 2022Relaxation time T2 is very useful for early detection of osteoarthritis in the knee articular cartilage using magnetic resonance imaging, as this condition is characterized by the loss of collagen integrity and increase of water content that leads to an increase of the T2 value. In clinical settings, T2 mapping is usually performed with a multi-spin-echo sequence followed by a mono-exponential fitting. However, the dictionary-based method has enabled more accurate T2 estimates by matching the multi-spin-echo data to a dictionary of pre-computed echo modulation curve. The focus of this dissertation is to compare different multi-spin-echo protocols for T2 mapping, in a phantom, by varying the flip angle of the refocusing radiofrequency pulse, as this affects the total acquisition time in order to meet the restrictions on the specific absorption rate, to find the most suitable protocol for in vivo acquisitions in the knee articular cartilage. A series of acquisitions were performed with the different multi-spin-echo sequence protocols on the ISMRM/ NIST phantom with a 3.0 T scanner, varying only the refocusing pulse flip-angle from [90, 120:5:145, 180]º, creating T2 maps through a mono-exponential fitting and echo modulation curve match for each protocol. The results obtained for both methods confirm a higher accuracy of T2 estimates with echo modula tion curve match compared to mono-exponential fitting. The comparison of the estimates obtained for the different protocols with the dictionary-based method showed reasonable values, however the 125º was considered the most suitable flip angle protocol for the in vivo acquisitions. The intra-scanner repro ducibility of the method for the selected protocol showed reliable results, exhibiting similar estimates for the three repetitions. This protocol was subsequently used in preliminary in vivo tests, with application of the dictionary method in three asymptomatic healthy subjects, obtaining promising values, of 32.3±8.8 ms; 36.9±10.5 ms; 36.7±9.5 ms, compared to the literature, which presents T2 values for a healthy knee cartilage at around 33.0 ms. The impact that physical stress has on the estimates of T2 in cartilage was also studied, revealing a decrease in the relaxation time after direct impact on the articular cartilage (T2 at rest vs stress, 36.7±9.5 ms vs 34.6±10.1 ms and 36.0±9.1 ms vs 34.9±10.1 ms, for the right and left knees, respectively). The overall results of this work presented a practical multi-spin-echo protocol for clinical use of knee cartilage imaging to create T2 maps estimated with the dictionary-based method.Nunes, Rita Gouveia, 1976-Conceição, Raquel Cruz daRepositório da Universidade de LisboaNunes, Ângelo Trindade2022-07-06T10:45:37Z202220212022-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://hdl.handle.net/10451/53671enginfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-11-08T16:59:41Zoai:repositorio.ul.pt:10451/53671Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T22:04:37.326513Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Optimizing T2 Quantitative Estimation of Knee Cartilage with Magnetic Resonance Imaging Applying Dictionary-based Methods
title Optimizing T2 Quantitative Estimation of Knee Cartilage with Magnetic Resonance Imaging Applying Dictionary-based Methods
spellingShingle Optimizing T2 Quantitative Estimation of Knee Cartilage with Magnetic Resonance Imaging Applying Dictionary-based Methods
Nunes, Ângelo Trindade
Mapas T2
Imagem por Ressonância Magnética
Método do Dicionário
Osteoartrite
Sequência Multi-Spin-Echo
Teses de mestrado - 2022
Departamento de Física
title_short Optimizing T2 Quantitative Estimation of Knee Cartilage with Magnetic Resonance Imaging Applying Dictionary-based Methods
title_full Optimizing T2 Quantitative Estimation of Knee Cartilage with Magnetic Resonance Imaging Applying Dictionary-based Methods
title_fullStr Optimizing T2 Quantitative Estimation of Knee Cartilage with Magnetic Resonance Imaging Applying Dictionary-based Methods
title_full_unstemmed Optimizing T2 Quantitative Estimation of Knee Cartilage with Magnetic Resonance Imaging Applying Dictionary-based Methods
title_sort Optimizing T2 Quantitative Estimation of Knee Cartilage with Magnetic Resonance Imaging Applying Dictionary-based Methods
author Nunes, Ângelo Trindade
author_facet Nunes, Ângelo Trindade
author_role author
dc.contributor.none.fl_str_mv Nunes, Rita Gouveia, 1976-
Conceição, Raquel Cruz da
Repositório da Universidade de Lisboa
dc.contributor.author.fl_str_mv Nunes, Ângelo Trindade
dc.subject.por.fl_str_mv Mapas T2
Imagem por Ressonância Magnética
Método do Dicionário
Osteoartrite
Sequência Multi-Spin-Echo
Teses de mestrado - 2022
Departamento de Física
topic Mapas T2
Imagem por Ressonância Magnética
Método do Dicionário
Osteoartrite
Sequência Multi-Spin-Echo
Teses de mestrado - 2022
Departamento de Física
description Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Engenharia Clínica e Instrumentação Médica) Universidade de Lisboa, Faculdade de Ciências, 2022
publishDate 2021
dc.date.none.fl_str_mv 2021
2022-07-06T10:45:37Z
2022
2022-01-01T00:00:00Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/masterThesis
format masterThesis
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10451/53671
url http://hdl.handle.net/10451/53671
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron:RCAAP
instname_str Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron_str RCAAP
institution RCAAP
reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository.name.fl_str_mv Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
repository.mail.fl_str_mv
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