Avaliação ultrassonográfica e por ressonância magnética da glândula tireoide hígida em equinos adultos
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Data
2018-11-12
Autores
Viana, Gustavo Fernandes
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Há poucos estudos disponíveis sobre a aplicação da ultrassonografia para o diagnóstico de tireopatias em equinos e, até onde sabemos, nenhuma pesquisa foi descrita utilizando a ressonância magnética (RM) para o estudo da glândula tireoide em cavalos. Foi observado em alguns relatos de casos que o lobo tireoidiano hígido serviu de base para a avaliação do lobo contralateral alterado. Entretanto, não existem estudos mostrando a relação entre o lobo tireoidiano esquerdo e direito através de técnicas imaginológicas em equinos. A análise de reprodutibilidade pode ser usada para estimar a variação biológica e metodológica para aprovar o processo de validação dos dados. Inicialmente, este estudo objetivou determinar a confiabilidade das medidas tireoidianas, a partir da comparação entre os lobos tireoidianos esquerdo e direito; bem como avaliar os contornos, formatos, ecotextura e ecogenicidade dos lobos tireoidianos através da ultrassonografia em modo B; quali-quantitativamente caracterizar a vascularização da glândula tireoide equina através da ferramenta Doppler. For fim, este trabalho objetivou, a partir da RM, selecionar as melhores sequências de imagens através da avaliação dos contornos, intensidade e homogeneidade do sinal da glândula tireoide hígida; determinar a confiabilidade das medidas tireoidianas, através da comparação entre os lobos tireoidianos esquerdo e direito; bem como avaliar os contornos, formatos de seus lobos e, por fim, descrever as principais estruturas anatômicas da porção ventroproximal do pescoço dos cavalos. Inicialmente, 13 cavalos com idade avançada (fator de risco para tireopatias) e clinicamente certificados de ausência de aumento de volume no pescoço foram incluídos neste estudo. Deste modo, onze cavalos com lobos tireoidianos hígidos foram selecionados através de testes laboratoriais, ultrassonografia e citologia da tireoide. Essas glândulas foram sequencialmente submetidas à análise por ultrassonografia e RM. Concluiu-se que não houve diferença entre os valores obtidos pelo estudo Doppler da artéria tireoidiana cranial esquerda e direita, sugerindo que a análise unilateral de uma das artérias pode ser utilizada como método para avaliar distúrbios difusos tireoidianos. Por RM, concluiu-se que as sequências dorsal spin eco ponderada em T1, sagital fast gradiente eco ponderada em T1, sagital fast spin eco ponderada em T2 e sagital STIR melhor caracterizaram a glândula tireoide quanto à definição de seus contornos e contraste de intensidade de sinal, em relação aos tecidos adjacentes. Tanto por ultrassonografia, como por RM, verificaram-se: diferenças qualitativas entre os formatos dos lobos tireoidianos direito e esquerdo e excelentes reprodutibilidades, com relação às mensurações realizadas. Deste modo, podemos sugerir que tais diferenças entre o formato dos lobos tireoidianos podem ser explicadas pela diferença significativa e/ou tendência observada no parâmetro de comprimento entre os lobos tireoidianos em ambas as metodologias de imagem. A ultrassonografia e RM foram complementares na caracterização da largura e altura da dos lobos tireoidianos, respectivamente.
There are few studies available on the application of ultrasonography for the diagnosis of equine thyropaties and, to the best of our knowledge, no studies have been reported demonstrating the use of magnetic resonance imaging (MRI) in thyroid evaluation in horses. It was observed in some case reports that the healthy thyroid lobe served as model for the evaluation of the altered contralateral lobe. However, there are no studies showing a positive relation between the left and right lobes by using ultrasonography and MRI in horses. Reproducibility analysis can be used to estimate the biological and methodological variation to approve the data validation process. Initially this study aimed at determining reliably of the thyroid measurements from the comparison between the left and right thyroid lobes, as well as assessing the contour, format, echotexture and echogenicity of the thyroid lobes by mode-B ultrasonography. Additionally, the equine thyroid gland vascularization was quali-quantitatively characterized the by Doppler tool. Finally, through the MRI, this study aimed to select the best imaging sequences by the evaluation the contours, intensity and homogeneity of signal of the normal thyroid; to determinate reliably their measurements from the comparison between the left and right thyroid lobes, as well as assessing the format thyroid lobes and to describe the main anatomical structures of the neck ventroproximal portion. The sample size initially was determined by the animal selection with advanced age and without volume increase in the neck proximal region. Finally, eleven horses were selected by laboratory test, search of thyroid neoformations by ultrasonography and cytology thyroid. Next, these animals were submitted to thyroid lobes evaluation by ultrasonography and MRI. It was concluded that there was no significant difference was found between the values of the left cranial thyroid artery compared to those obtained in the right cranial thyroid artery, suggesting that the analysis of the unilateral cranial thyroid artery spectral Doppler values can be used as a method for evaluating diffuse thyroid disorders. By MRI, it was concluded that the dorsal spin echo T1-weighted, sagittal fast gradient echo T1-weighted, fast spin echo T2-weighted and sagittal STIR were the sequences that best characterized the thyroid gland regarding the definition of its contours and signal intensity contrast in relation to the adjacent tissues. By ultrasonography and MRI, there were: qualitative differences between the formats of the right and left thyroid lobes and excellent reproducibility in relation to the measurements performed. Thus, we can suggest that such differences between the format of the thyroid lobes can be explained by the significant difference and/or tendency observed in the length parameter between the thyroid lobes in both imaging methodologies. The ultrasonography and MRI were complementary in the characterization of the width and height of the thyroid lobes, respectively.
There are few studies available on the application of ultrasonography for the diagnosis of equine thyropaties and, to the best of our knowledge, no studies have been reported demonstrating the use of magnetic resonance imaging (MRI) in thyroid evaluation in horses. It was observed in some case reports that the healthy thyroid lobe served as model for the evaluation of the altered contralateral lobe. However, there are no studies showing a positive relation between the left and right lobes by using ultrasonography and MRI in horses. Reproducibility analysis can be used to estimate the biological and methodological variation to approve the data validation process. Initially this study aimed at determining reliably of the thyroid measurements from the comparison between the left and right thyroid lobes, as well as assessing the contour, format, echotexture and echogenicity of the thyroid lobes by mode-B ultrasonography. Additionally, the equine thyroid gland vascularization was quali-quantitatively characterized the by Doppler tool. Finally, through the MRI, this study aimed to select the best imaging sequences by the evaluation the contours, intensity and homogeneity of signal of the normal thyroid; to determinate reliably their measurements from the comparison between the left and right thyroid lobes, as well as assessing the format thyroid lobes and to describe the main anatomical structures of the neck ventroproximal portion. The sample size initially was determined by the animal selection with advanced age and without volume increase in the neck proximal region. Finally, eleven horses were selected by laboratory test, search of thyroid neoformations by ultrasonography and cytology thyroid. Next, these animals were submitted to thyroid lobes evaluation by ultrasonography and MRI. It was concluded that there was no significant difference was found between the values of the left cranial thyroid artery compared to those obtained in the right cranial thyroid artery, suggesting that the analysis of the unilateral cranial thyroid artery spectral Doppler values can be used as a method for evaluating diffuse thyroid disorders. By MRI, it was concluded that the dorsal spin echo T1-weighted, sagittal fast gradient echo T1-weighted, fast spin echo T2-weighted and sagittal STIR were the sequences that best characterized the thyroid gland regarding the definition of its contours and signal intensity contrast in relation to the adjacent tissues. By ultrasonography and MRI, there were: qualitative differences between the formats of the right and left thyroid lobes and excellent reproducibility in relation to the measurements performed. Thus, we can suggest that such differences between the format of the thyroid lobes can be explained by the significant difference and/or tendency observed in the length parameter between the thyroid lobes in both imaging methodologies. The ultrasonography and MRI were complementary in the characterization of the width and height of the thyroid lobes, respectively.
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Palavras-chave
MRI, Ultrasound, Thyroid lobes, Equine, Ultrassom, Lobos tireoidianos, Cavalo, RM