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Objetivo: A presente dissertação tem como objetivo principal, a avaliação de parâmetros de qualidade imagiológica em estudos pélvicos para as técnicas HASTE e T2 TSE, nomeadamente a relação sinal-ruído, a presença de artefactos, a avaliação de estruturas anatómicas e conspicuidade de patologias presentes, num equipamento de RM de 1,5 T. Métodos: Foram incluídos no estudo 50 exames de RM pélvica realizados a participantes adultos, sem limite de idade e de ambos os sexos. Os parâmetros da técnica T2 TSE foram obtidos a partir do protocolo intrínseco da Instituição Hospitalar, em exames de RM pélvica. Na técnica HASTE, os parâmetros foram obtidos e otimizados, a partir de recomendações recolhidas na literatura. Dois médicos radiologistas foram convidados a preencher um questionário de avaliação qualitativa das imagens, segundo uma escala de Likert, conforme os parâmetros de qualidade imagiológica estabelecidos. Com o objetivo de avaliar quantitativamente as imagens deste estudo, foram delimitadas seis ROI em estruturas anatómicas específicas da região pélvica. Resultados: A técnica HASTE apresentou resultados com maior compatibilidade quanto à classificação de “Imagem com qualidade aceitável”, devido à presença de algum ruído (𝑥̅ = 3,20±0,47), delineação aceitável de estruturas anatómicas (𝑥̅ = 3,49±0,48), e delineação aceitável de patologias presentes (𝑥̅ = 3,34±0,50). A técnica T2 TSE apresentou resultados de pouco ruído observado (𝑥̅ = 4.37±0,38), boa delineação de estruturas anatómicas (𝑥̅ = 4,14±0,27) e boa delineação de patologias presentes (𝑥̅ = 4,09±0,34), o que confere uma classificação de “Imagem com boa qualidade”. Verificaram-se valores médios inferiores para a técnica HASTE, relativamente ao músculo Piriforme, Próstata, Miométrio e Zona Juncional (74,65±29,05, 176,79±36,88, 196,75±73,02 e 139,44±48,08 respetivamente), contrariamente à técnica T2 TSE (77,47±25,42, 199,03±39,44, 217,65±77,47 e 147,47±50,20 respetivamente), porém, os valores em HASTE são superiores para o tecido adiposo anterior e posterior (470,02±157,58 e 592,54±56,47) comparativamente a T2 TSE (441,99±90,42 e 543,58±57,04). Nos questionários de avaliação subjetiva, observaram-se elevadas percentagens de concordância em algumas respostas facultadas, ou seja, os observadores tendencialmente concordam com as afirmações, porém, não concordam com a magnitude do valor atribuído. Assim sendo, os valores de coeficiente de Kappa, indicam uma discordância total na avaliação inter-observador (Kappa < 0,20). Conclusão: Apesar de se observar uma diminuição de 71,4% no tempo de aquisição técnica HASTE relativamente à técnica T2 TSE, os resultados da qualidade de imagem obtidos por esta técnica ultrarrápida, não são os ideais para se substituir a técnica T2 TSE.
ABSTRACT - Objective: The main objective of this dissertation is the evaluation of imaging quality parameters in pelvic studies for HASTE and T2 TSE techniques, namely the signal-to-noise ratio, the presence of artifacts, the evaluation of anatomical structures and conspicuity of pathologies present, in a 1.5 T MRI equipment. Methods: Fifty pelvic MRI scans performed on adult participants of both sexes without age limits were included in the study. T2 TSE parameters were obtained from the hospital's intrinsic protocol for pelvic MRI scans. For the HASTE technique, the parameters were obtained and optimized based on recommendations from the literature. Two radiologists were asked to complete a questionnaire for qualitative evaluation of the images, using a Likert scale, according to the established imaging quality parameters. In order to quantitatively evaluate the images in this study, six ROIs were delineated in specific anatomical structures of the pelvic region. Results: The HASTE technique presented results with greater compatibility regarding the classification of “Image with acceptable quality”, due to the presence of some noise (𝑥̅ = 3.20±0.47), acceptable delineation of anatomical structures (𝑥̅ = 3.49±0.48), and acceptable delineation of present pathologies (𝑥̅ = 3.34±0.50). The T2 TSE technique presented results of low noise (𝑥̅ = 4.37±0.38), good delineation of anatomical structures (𝑥̅ = 4.14±0.27), and good delineation of present pathologies (𝑥̅ = 4.09±0.34), which gives a classification of “Image with good quality”. Lower mean values were found for the HASTE technique, for the Piriform muscle, Prostate, Myometrium, and Junctional Zone (74.65±29.05, 176.79±36.88, 196.75±73.02 and 139.44±48.08 respectively), compared to the T2 TSE technique (77.47±25.42, 199.03±39.44, 217.65±77.47 and 147.47±50.20 respectively), however, the HASTE values are higher for the anterior and posterior adipose tissue (470.02±157.58 and 592.54±56.47) compared to the T2 TSE technique (441.99±90.42 and 543.58±57.04). In the subjective assessment questionnaires, high percentages of agreement were observed in some of the answers provided, meaning that observers tended to agree with the statements, but did not agree with the magnitude of the value assigned. Thus, the Kappa coefficient values indicate a total disagreement in the inter-observer evaluation (Kappa < 0.20). Conclusion: Despite a 71.4% reduction in acquisition time for the HASTE technique compared with the T2 TSE technique, the image quality results obtained by this ultra-fast technique are not ideal for replacing the T2 TSE technique.
ABSTRACT - Objective: The main objective of this dissertation is the evaluation of imaging quality parameters in pelvic studies for HASTE and T2 TSE techniques, namely the signal-to-noise ratio, the presence of artifacts, the evaluation of anatomical structures and conspicuity of pathologies present, in a 1.5 T MRI equipment. Methods: Fifty pelvic MRI scans performed on adult participants of both sexes without age limits were included in the study. T2 TSE parameters were obtained from the hospital's intrinsic protocol for pelvic MRI scans. For the HASTE technique, the parameters were obtained and optimized based on recommendations from the literature. Two radiologists were asked to complete a questionnaire for qualitative evaluation of the images, using a Likert scale, according to the established imaging quality parameters. In order to quantitatively evaluate the images in this study, six ROIs were delineated in specific anatomical structures of the pelvic region. Results: The HASTE technique presented results with greater compatibility regarding the classification of “Image with acceptable quality”, due to the presence of some noise (𝑥̅ = 3.20±0.47), acceptable delineation of anatomical structures (𝑥̅ = 3.49±0.48), and acceptable delineation of present pathologies (𝑥̅ = 3.34±0.50). The T2 TSE technique presented results of low noise (𝑥̅ = 4.37±0.38), good delineation of anatomical structures (𝑥̅ = 4.14±0.27), and good delineation of present pathologies (𝑥̅ = 4.09±0.34), which gives a classification of “Image with good quality”. Lower mean values were found for the HASTE technique, for the Piriform muscle, Prostate, Myometrium, and Junctional Zone (74.65±29.05, 176.79±36.88, 196.75±73.02 and 139.44±48.08 respectively), compared to the T2 TSE technique (77.47±25.42, 199.03±39.44, 217.65±77.47 and 147.47±50.20 respectively), however, the HASTE values are higher for the anterior and posterior adipose tissue (470.02±157.58 and 592.54±56.47) compared to the T2 TSE technique (441.99±90.42 and 543.58±57.04). In the subjective assessment questionnaires, high percentages of agreement were observed in some of the answers provided, meaning that observers tended to agree with the statements, but did not agree with the magnitude of the value assigned. Thus, the Kappa coefficient values indicate a total disagreement in the inter-observer evaluation (Kappa < 0.20). Conclusion: Despite a 71.4% reduction in acquisition time for the HASTE technique compared with the T2 TSE technique, the image quality results obtained by this ultra-fast technique are not ideal for replacing the T2 TSE technique.
Descrição
Mestrado de Radiações Aplicadas às Tecnologias da Saúde. - Área de especialização: Imagem por Ressonância Magnética
Palavras-chave
Ressonância magnética HASTE T2 TSE Qualidade de imagem Variabilidade interobservador Magnetic resonance Image quality Inter-observer variability
Contexto Educativo
Citação
Cabrita TC. Estudo da técnica Half-Fourier Acquisition Single-shot Turbo spin Eco versus T2 Turbo Spin Eco em exames pélvicos de ressonância magnética em 1,5 Tesla [dissertation]. Lisboa: Escola Superior de Tecnologia da Saúde de Lisboa/Instituto Politécnico de Lisboa; 2023.
Editora
Instituto Politécnico de Lisboa, Escola Superior de Tecnologia da Saúde de Lisboa