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Nonalcoholic fatty liver disease is a common condition associated with metabolic syndrome. It is the most common cause of elevated liver enzymes in U.S. adults, and is diagnosed after ruling out other causes of steatosis (fatty infiltration of liver), particularly infectious hepatitis and alcohol abuse. Liver biopsy may be considered if greater diagnostic and prognostic certainty is desired, particularly in patients with diabetes, patients who are morbidly obese, and in patients with an aspartate transaminase to alanine transaminase ratio greater than one, because these patients are at risk of having more advanced disease. Weight loss is the primary treatment for obese patients with nonalcoholic fatty liver disease. Medications used to treat insulin resistance, hyperlipidemia, and obesity have been shown to improve transaminase levels, steatosis, and histologic findings. However, no treatments have been shown to affect patient-oriented outcomes.

BACKGROUND: There has been renewed interest in the study of brown adipose tissue (BAT) as a potential therapeutic target for obesity, diabetes and non-alcoholic fatty liver disease (NAFLD). There is now much evidence to suggest that BAT is not only important in thermogenesis but also plays an important role in metabolism. In adults, cold-induced BAT activation has led to a significant increase in insulin sensitivity and energy expenditure as well as decreased blood sugar levels. Thus, it is important to identify factors associated with these metabolic disorders such as the presence and activity of BAT to better understand if and how BAT can be targeted to treat these disorders. However, as a potential therapeutic target, it is important to develop accurate, precise, robust and reproducible non-invasive modalities to measure BAT. PROJECT OBJECTIVES: 1) Develop and assess protocols for the use of MRI in measuring BAT characteristics and activity 2) Examine the relationship between BAT MR outcomes and known covariates such as age, sex, body fat percentage and outdoor temperature in adult humans 3) Determine if there is any association between BAT outcomes and liver fat in adult humans, before and after adjusting for potential covariates of liver fat such as age, sex and body fat percentage METHODS: In total, 36 healthy participants (i.e. no conditions or medications that could influence BAT metabolism and/or liver disease) aged 18 to 60 years were recruited to this cross-sectional study. There were two study visits. In visit 1, anthropometrics (i.e. height, weight and waist circumference), blood pressure and body composition (via dual x-ray energy absorptiometry) were measured. Additionally, fasting bloodwork was collected and a 75-g oral glucose tolerance test (OGTT) was administered. During visit 2, participants were exposed to a standardized cold exposure set at 18°C for 3 hours using a water-perfused suit. MRI scans were acquired to evaluate changes in fat-fraction (FF%) and T2* relaxation (T2*) (BAT MR outcomes), liver fat and abdominal fat after a cold exposure. During the cold exposure protocol, mean skin temperature (MST) was monitored using 12 wireless temperature loggers placed at different sites of the body while electromyography (EMG) was used to measure shivering intensity. RESULTS: In the current study, an MRI protocol capable of detecting BAT in the supraclavicular (SCV) region was developed. This protocol included the use of FF and T2* masks to more accurately characterize BAT in the SCV region. Additionally, the MR segmentation protocol was found to be very reliable, as demonstrated by excellent ICC values (i.e. ICCagreement and ICCconsistency ≥ 0.90) for all BAT MR outcomes irrespective of cold exposure. As expected, FF% (mean difference = -2.97; p < 0.0001*) and T2* (mean difference = -0.84; p < 0.0001*) values in the SCV significantly decreased after cold exposure, consistent with BAT activation. Furthermore, the decline in both FF% and T2* after cooling was specific to the SCV region, as these changes did not occur in the posterior neck fat. In examining the relationship between BAT MR outcomes and known covariates of BAT (i.e. age, sex, body fat percentage and outdoor temperature), it is important to note that lower FF% or T2* values are reflective of a browner phenotype while a greater reduction in FF% is indicative of higher BAT activity. BAT characteristics (A: pre-cold FF%; B: pre-cold T2*) and BAT activity (C: FF% reduction) were correlated with age (A: r = 0.54; p = 0.0007*; B: r = 0.42; p = 0.0112*; C: r = -0.39; p = 0.0213*) and body fat percentage (A: r = 0.83; p < 0.0001*; B: r = 0.58; p = 0.0002*; C: r = -0.64; p < 0.0001*). That is, higher age and body fat were associated with a less brown phenotype prior to cold exposure and with less BAT activity (i.e. lower FF% decline) in response to cold exposure. However, no associations were found between BAT MR outcomes and sex or outdoor temperature. Lastly, liver fat was associated with higher values of pre-cold FF% (r = 0.60; p < 0.0001*) and pre-cold T2* (r = 0.47; p = 0.0040*) while FF% reduction was inversely correlated with liver fat (r = -0.38; p = 0.0295*). Additionally, the relationship between BAT MR outcomes and liver fat still existed after adjusting for age and sex while its effects were mediated by adiposity. CONCLUSION: In this study, a highly reliable MR segmentation protocol was developed that is capable of measuring BAT characteristics and activity irrespective of cold exposure. Additionally, the cold exposure protocol used was sufficient to elicit changes in BAT MR outcomes, as demonstrated by significant changes in FF% and T2* after cooling. Consistent with previous studies, BAT outcomes (as measured by MRI) were associated with age and body fat percentage. Lastly, findings in this thesis provide strong supporting data that BAT may regulate liver lipid content, however, the extent and mechanisms remain to be determined. / Thesis / Master of Science (MSc)

A esteatose hepática é caracterizada histologicamente pelo acúmulo de triglicerídeos no citoplasma dos hepatócitos. A biópsia ainda é o padrão ouro para diagnóstico e avaliação da gravidade, no entanto, é um método invasivo e sujeita a erro de amostragem. Com os avanços dos métodos diagnósticos por imagem, a RM se tornou um método bem estabelecido para detecção e quantificação da esteatose. A maneira mais simples é a obtenção do cálculo da fração de gordura pela técnica gradiente-eco desvio químico. Todavia, não há estudos demonstrando a melhor forma de medir a intensidade de sinal para esse cálculo. Em nosso estudo, através da revisão de exames de RM, avaliamos três diferentes estratégias de medidas para quantificação com amostra de conveniência com 74 exames apresentando esteatose pareados em dois grupos, esteatose homogênea (n=37) e heterogênea (n=37). No grupo de esteatose heterogênea, o uso de ROI de 1cm² para medir a intensidade de sinal na área mais alterada apresentou variações significativas na quantificação, enquanto a média de quatro ROIs de 1cm² ou a segmentação de área representativa em corte axial não apresentaram variações significativas. Na esteatose hepática homogênea, qualquer estratégia utilizada não demonstrou diferença significativa. O coeficiente de correlação intraclasse variou entre 0,96 e 0,99, com IC 95% de 0,93-0,99. Assim, a quantificação da gordura hepática por RM utilizando apenas um ROI é menos representativa, principalmente na esteatose heterogênea. Não houve diferença significativa entre a obtenção da média de 4 ROIs e a segmentação de área representativa do parênquima. / Hepatic steatosis is characterized histologically by the triglyceride accumulation in the cytoplasm of hepatocytes. A biopsy is still considered the gold standard for diagnosis and assessment of severity, however, is an invasive and subject to sampling error method. With the improvement of diagnostic imaging methods, MRI has become a well-established method for the detection and quantification of liver fat. The easiest way is to obtain the calculation of the fat fraction by GRE technique with chemical shift technique. However, there are no studies demonstrating the best way to measure the signal intensity for this calculation. In our study by MRI review, we evaluate three different strategies for measuring the signal intensity with a convenience sample of 74 exams showing steatosis paired into two groups, diffuse steatosis (n = 37) and heterogeneous (n = 37). In heterogeneous steatosis group, the strategy with a ROI of 1 cm² to measure the signal intensity in the most altered area showed significant variations in the quantification, while the average of four ROIs of 1cm² or representative target area in axial section did not vary significant. In diffuse hepatic steatosis, any strategy used showed no significant difference. The intraclass correlation coefficient ranged between 0.96 and 0.99, with 95% of 0.93-0.99. Thus, the quantification of fat liver by MRI using only ROI is less representative, especially in heterogeneous steatosis. There was no significant difference between the average of 4 ROIs strategy and the strategy of representative segmentation area of parenchyma.

Shen, Jiayun. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 166-199). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

A esteatose hepática é caracterizada histologicamente pelo acúmulo de triglicerídeos no citoplasma dos hepatócitos. A biópsia ainda é o padrão ouro para diagnóstico e avaliação da gravidade, no entanto, é um método invasivo e sujeita a erro de amostragem. Com os avanços dos métodos diagnósticos por imagem, a RM se tornou um método bem estabelecido para detecção e quantificação da esteatose. A maneira mais simples é a obtenção do cálculo da fração de gordura pela técnica gradiente-eco desvio químico. Todavia, não há estudos demonstrando a melhor forma de medir a intensidade de sinal para esse cálculo. Em nosso estudo, através da revisão de exames de RM, avaliamos três diferentes estratégias de medidas para quantificação com amostra de conveniência com 74 exames apresentando esteatose pareados em dois grupos, esteatose homogênea (n=37) e heterogênea (n=37). No grupo de esteatose heterogênea, o uso de ROI de 1cm² para medir a intensidade de sinal na área mais alterada apresentou variações significativas na quantificação, enquanto a média de quatro ROIs de 1cm² ou a segmentação de área representativa em corte axial não apresentaram variações significativas. Na esteatose hepática homogênea, qualquer estratégia utilizada não demonstrou diferença significativa. O coeficiente de correlação intraclasse variou entre 0,96 e 0,99, com IC 95% de 0,93-0,99. Assim, a quantificação da gordura hepática por RM utilizando apenas um ROI é menos representativa, principalmente na esteatose heterogênea. Não houve diferença significativa entre a obtenção da média de 4 ROIs e a segmentação de área representativa do parênquima. / Hepatic steatosis is characterized histologically by the triglyceride accumulation in the cytoplasm of hepatocytes. A biopsy is still considered the gold standard for diagnosis and assessment of severity, however, is an invasive and subject to sampling error method. With the improvement of diagnostic imaging methods, MRI has become a well-established method for the detection and quantification of liver fat. The easiest way is to obtain the calculation of the fat fraction by GRE technique with chemical shift technique. However, there are no studies demonstrating the best way to measure the signal intensity for this calculation. In our study by MRI review, we evaluate three different strategies for measuring the signal intensity with a convenience sample of 74 exams showing steatosis paired into two groups, diffuse steatosis (n = 37) and heterogeneous (n = 37). In heterogeneous steatosis group, the strategy with a ROI of 1 cm² to measure the signal intensity in the most altered area showed significant variations in the quantification, while the average of four ROIs of 1cm² or representative target area in axial section did not vary significant. In diffuse hepatic steatosis, any strategy used showed no significant difference. The intraclass correlation coefficient ranged between 0.96 and 0.99, with 95% of 0.93-0.99. Thus, the quantification of fat liver by MRI using only ROI is less representative, especially in heterogeneous steatosis. There was no significant difference between the average of 4 ROIs strategy and the strategy of representative segmentation area of parenchyma.

Introdução: A incidência de obesidade é crescente e alarmante, principalmente no mundo ocidental. De acordo com o National Center for Health Statistics, cerca de 61% da população adulta nos Estados Unidos está acima do peso e 30% é obesa, sendo que 5 a 6% está classificada na faixa de obesidade Grau III. No Brasil, o Ministério da Saúde aponta que 32,9% dos brasileiros estão fora da faixa de peso ideal, e 4,8% dos homens e 11,7% das mulheres encaixam-se na faixa de obesidade Grau III. Devido a alta prevalência da Doença Hepática Gordurosa Não Alcoólica (DHGNA) em pacientes portadores de obesidade grave e os escassos conhecimentos acerca de sua evolução para doença crônica do fígado após cirurgias bariátricas, foram objetivos deste estudo avaliar os efeitos da cirurgia gastrorredutora com derivação intestinal em Y de Roux Cirurgia de Fobi-Capella) sobre DHGNA após 24 meses. Métodos: Dentre 40 pacientes com IMC > 40 kg/m2 submetidos à cirurgia bariátrica (cirurgia de Fobi-Capella) no período de 2001 a 2003, 18 pacientes foram seguidos por aproximadamente 24 meses (700 ± 42 dias) e incluídos no estudo, realizando-se exames laboratoriais, tais como enzimas hepáticas, perfil lipídico e glicêmico; e a biopsia hepática no perioperatório e 24 meses após a cirurgia. O diagnóstico histológico de DHGNA e Esteatohepatite Não Alcoólica (ENA) foi determinado segundo a classificação padronizada por meio da revisão pelo Pathology Committee of the NASH Clinical Research Network Americano, que designou e validou as características histológicas e um sistema de escore de atividade para DHGNA para estudos clínicos. esultados: O IMC médio inicial dos 18 pacientes foi de 51,7 ± 7 kg/m2 e na segunda biopsia, após 24 meses de seguimento foi de 32,3 ± 6 kg/m2, com excesso do índice de massa corpórea perdida de 72,56%. DHGNA foi constatada no exame histológico inicial em 100% dos pacientes, sendo steatohepatite em 67% (10 pacientes com escore de atividade da DHGNA maior ou igual a 5 e dois pacientes com escore 4 com algum grau de fibrose) e 33% com esteatose isolada. Dos pacientes com ENA, 8,3% apresentavam cirrose. Após cerca de 24 meses houve desaparecimento da esteatose em 89% e manutenção da esteatose Grau I em 11% (p < 0,001). Em relação à fibrose, observada inicialmente em 10 (55%) dos pacientes, somente 4 (22,22%) dos pacientes mantiveram algum grau de fibrose (p = 0,020). No que se refere ao infiltrado inflamatório, 78% mantiveram discreto infiltrado lobular (Grau I) não relacionado à degeneração gordurosa. A balonização hepatocelular desapareceu em 50% dos pacientes e manteve-se discreta (Grau I) em 50% (p < 0,001). Não houve diferença estatística no que se refere às aminotranferases no pré e pós-operatório tardio. Houve redução significativa dos lípides e glicemia em quase a totalidade dos pacientes. Conclusão: A correção da síndrome metabólica obtida pela acentuada perda de peso após cirurgia de Fobi-Capella promoveu melhora da esteatose, fibrose, e os escores de atividade da DHGNA menores que 5, respectivamente em 89%, 75% e 100%dos pacientes previamente portadores de DHGNA, não se observando efeito deletério na histologia hepática nesta série. / Background: The incidence of obesity is increasing in western countries at an alarming rate. The National Center for Health Statistics of United Stated estimated in adult population 61% the prevalence of overweight or obesity, and 30% has obesity, and 5 to 6% were classified in severe obesity. In Brazil, the Ministry of Health reported 32.9% the prevalence of overweight or obese in adult brazilian population, and severe obesity 4.8% were men and 11.7% were women. Although nonalcoholic fatty liver disease (NAFLD) has been proved very frequent among morbidly obese patients and the effect of weight loss after bariatric surgery in inflammation and fibrosis related NAFLD is still a matter of debate. The aim of this study was to evaluate the impact of Fobi-Capella surgery in NAFLD in a follow up of 24 months. Methods: Forty patients with body mass index (BMI) IMC > 40 kg/m2 were submitted to Roux-en-Y gastric bypass with intraoperatory liver biopsies between 2001 a 2003, and 18 patients were followed and selected to underwent a liver biopsies after 24 months (700 ± 42 days). Blood biochemical tests and liver histology were compared before and after weight loss. The histological diagnosis of Nonalcoholic fatty liver disease (NAFLD) and Nonalcoholic steatohepatitis (NASH) was analyzed using the classification proposed by Pathology Committee of the NASH Clinical Research Network, which designed and validated a histological feature scoring system that address the characteristics of NASH lesions and a NAFLD activity score (NAS) for use in clinical trials. Eighteen patients with body mass index >40 kg/m2 submitted to Roux-n-Y gastric bypass were enrolled, and wedge liver biopsy was obtained at the operation. After 24 months, patients agreed to be submitted to a percutaneous liver biopsy. Results: The initial average BMI of 18 patientes were 51.7 ± 7 kg/m2. After following 24 months, average BMI was 32.3 ± 6 kg/m2. The average of percent excess body mass index loss was 72.56%. NAFLD was present in all 18 patients at the initial biopsy, NASH in 67% (10 patient had score of NAS ? 5 and two patients with score 4 had some degree of fibrosis) and 33% with steatosis only; 8.3% of patients with NASH has cirrhosis. After 24 months steatosis disappeared in 89% (p < 0,001) and fibrosis disappeared in 60% of the patients (p = 0.020). Hepatocellular ballooning disappeared in 50% (p < 0.001). A slight lobular inflammatory infiltrate remained in 78%, apparently unrelated to fatty degeneration. Since liver biochemical variables AST and ALT had been found within normal limits in 88% and 89%, respectively of patients at initial biopsy, no difference was found 24 months later (p = 1.000). Lipid profile and blood sugar plasma concentration were closer to normal in all patients after 24 months of follow up (p < 0.05). Conclusions: The improvement of metabolic syndrome related a severe obesity after sustained weight loss surgery promoted significant improvement in liver histology. The steatosis, fibrosis and NAS ? 5 were decreased in 89%, 75% and 100% of patients, respectively. None patient had progression of hepatic fibrosis in this series.

Introdução: A incidência de obesidade é crescente e alarmante, principalmente no mundo ocidental. De acordo com o National Center for Health Statistics, cerca de 61% da população adulta nos Estados Unidos está acima do peso e 30% é obesa, sendo que 5 a 6% está classificada na faixa de obesidade Grau III. No Brasil, o Ministério da Saúde aponta que 32,9% dos brasileiros estão fora da faixa de peso ideal, e 4,8% dos homens e 11,7% das mulheres encaixam-se na faixa de obesidade Grau III. Devido a alta prevalência da Doença Hepática Gordurosa Não Alcoólica (DHGNA) em pacientes portadores de obesidade grave e os escassos conhecimentos acerca de sua evolução para doença crônica do fígado após cirurgias bariátricas, foram objetivos deste estudo avaliar os efeitos da cirurgia gastrorredutora com derivação intestinal em Y de Roux Cirurgia de Fobi-Capella) sobre DHGNA após 24 meses. Métodos: Dentre 40 pacientes com IMC > 40 kg/m2 submetidos à cirurgia bariátrica (cirurgia de Fobi-Capella) no período de 2001 a 2003, 18 pacientes foram seguidos por aproximadamente 24 meses (700 ± 42 dias) e incluídos no estudo, realizando-se exames laboratoriais, tais como enzimas hepáticas, perfil lipídico e glicêmico; e a biopsia hepática no perioperatório e 24 meses após a cirurgia. O diagnóstico histológico de DHGNA e Esteatohepatite Não Alcoólica (ENA) foi determinado segundo a classificação padronizada por meio da revisão pelo Pathology Committee of the NASH Clinical Research Network Americano, que designou e validou as características histológicas e um sistema de escore de atividade para DHGNA para estudos clínicos. esultados: O IMC médio inicial dos 18 pacientes foi de 51,7 ± 7 kg/m2 e na segunda biopsia, após 24 meses de seguimento foi de 32,3 ± 6 kg/m2, com excesso do índice de massa corpórea perdida de 72,56%. DHGNA foi constatada no exame histológico inicial em 100% dos pacientes, sendo steatohepatite em 67% (10 pacientes com escore de atividade da DHGNA maior ou igual a 5 e dois pacientes com escore 4 com algum grau de fibrose) e 33% com esteatose isolada. Dos pacientes com ENA, 8,3% apresentavam cirrose. Após cerca de 24 meses houve desaparecimento da esteatose em 89% e manutenção da esteatose Grau I em 11% (p < 0,001). Em relação à fibrose, observada inicialmente em 10 (55%) dos pacientes, somente 4 (22,22%) dos pacientes mantiveram algum grau de fibrose (p = 0,020). No que se refere ao infiltrado inflamatório, 78% mantiveram discreto infiltrado lobular (Grau I) não relacionado à degeneração gordurosa. A balonização hepatocelular desapareceu em 50% dos pacientes e manteve-se discreta (Grau I) em 50% (p < 0,001). Não houve diferença estatística no que se refere às aminotranferases no pré e pós-operatório tardio. Houve redução significativa dos lípides e glicemia em quase a totalidade dos pacientes. Conclusão: A correção da síndrome metabólica obtida pela acentuada perda de peso após cirurgia de Fobi-Capella promoveu melhora da esteatose, fibrose, e os escores de atividade da DHGNA menores que 5, respectivamente em 89%, 75% e 100%dos pacientes previamente portadores de DHGNA, não se observando efeito deletério na histologia hepática nesta série. / Background: The incidence of obesity is increasing in western countries at an alarming rate. The National Center for Health Statistics of United Stated estimated in adult population 61% the prevalence of overweight or obesity, and 30% has obesity, and 5 to 6% were classified in severe obesity. In Brazil, the Ministry of Health reported 32.9% the prevalence of overweight or obese in adult brazilian population, and severe obesity 4.8% were men and 11.7% were women. Although nonalcoholic fatty liver disease (NAFLD) has been proved very frequent among morbidly obese patients and the effect of weight loss after bariatric surgery in inflammation and fibrosis related NAFLD is still a matter of debate. The aim of this study was to evaluate the impact of Fobi-Capella surgery in NAFLD in a follow up of 24 months. Methods: Forty patients with body mass index (BMI) IMC > 40 kg/m2 were submitted to Roux-en-Y gastric bypass with intraoperatory liver biopsies between 2001 a 2003, and 18 patients were followed and selected to underwent a liver biopsies after 24 months (700 ± 42 days). Blood biochemical tests and liver histology were compared before and after weight loss. The histological diagnosis of Nonalcoholic fatty liver disease (NAFLD) and Nonalcoholic steatohepatitis (NASH) was analyzed using the classification proposed by Pathology Committee of the NASH Clinical Research Network, which designed and validated a histological feature scoring system that address the characteristics of NASH lesions and a NAFLD activity score (NAS) for use in clinical trials. Eighteen patients with body mass index >40 kg/m2 submitted to Roux-n-Y gastric bypass were enrolled, and wedge liver biopsy was obtained at the operation. After 24 months, patients agreed to be submitted to a percutaneous liver biopsy. Results: The initial average BMI of 18 patientes were 51.7 ± 7 kg/m2. After following 24 months, average BMI was 32.3 ± 6 kg/m2. The average of percent excess body mass index loss was 72.56%. NAFLD was present in all 18 patients at the initial biopsy, NASH in 67% (10 patient had score of NAS ? 5 and two patients with score 4 had some degree of fibrosis) and 33% with steatosis only; 8.3% of patients with NASH has cirrhosis. After 24 months steatosis disappeared in 89% (p < 0,001) and fibrosis disappeared in 60% of the patients (p = 0.020). Hepatocellular ballooning disappeared in 50% (p < 0.001). A slight lobular inflammatory infiltrate remained in 78%, apparently unrelated to fatty degeneration. Since liver biochemical variables AST and ALT had been found within normal limits in 88% and 89%, respectively of patients at initial biopsy, no difference was found 24 months later (p = 1.000). Lipid profile and blood sugar plasma concentration were closer to normal in all patients after 24 months of follow up (p < 0.05). Conclusions: The improvement of metabolic syndrome related a severe obesity after sustained weight loss surgery promoted significant improvement in liver histology. The steatosis, fibrosis and NAS ? 5 were decreased in 89%, 75% and 100% of patients, respectively. None patient had progression of hepatic fibrosis in this series.

Introdução: A obesidade é uma doença crônica que aumenta sua prevalência progressivamente no mundo todo. Uma das suas principais complicações é a doença hepática gordurosa não alcoólica (DHGNA), que pode apresentar-se de forma assintomática, com esteatose hepática, esteato-hepatite, cirrose e hepatocarcinoma. Está associada à dislipidemia, hipertensão, diabetes, síndrome metabólica e resistência insulínica. O padrão ouro para seu diagnóstico é a biopsia hepática, considerado método invasivo. Medidas indiretas são usadas para auxiliar na sua detecção, como dados do exame físico, exames de bioquímica e de imagem. Objetivo: Diagnosticar DHGNA usando a ressonância nuclear magnética (RNM) como método não invasivo, correlacionando-a com achados clínicos e laboratoriais. Metodologia: Estudo transversal de 50 crianças e adolescentes seguidas no Ambulatório de Obesidade do Hospital das Clínicas da FMRP-USP. Foram submetidas à questionário sobre histórico pessoal e familiar, à exame físico, exames laboratoriais (lipidograma, transaminases, glicemia e insulina basal) e RNM de abdome para cálculo da de gordura hepática, visceral e subcutânea. Resultados: Diagnosticado esteatose hepática em 14 (28%) dos participantes, sendo 8 com esteatose grave (porcentagem de gordura >18%) e 4 não grave (porcentagem gordura hepática entre 9 e 18%). Houve diferença estatisticamente significante entre a gordura hepática detectada pela RNM e o gênero masculino, triglicérides, TGO, TGP, relação TGO/TGP e acantose nigricans. O cálculo do Homeostasis Model Assessment Insulin Resistance (HOMA-IR) e da síndrome metabólica não apresentaram relação positiva com a porcentagem de gordura hepática. Conclusão: A frequência de esteatose hepática, utilizando a RNM como ferramenta diagnóstica, foi inferior à encontrada na literatura. Dos parâmetros estudados, os melhores preditores de esteatose hepática foram triglicérides, TGO, TGP, relação TGO/TGP, gênero masculino, acantose nigricans e Z escore para IMC elevado / Introduction: Obesity is a chronic disease whose prevalence progressively increasing worldwide. One of its main complications is non-alcoholic fatty liver disease (NAFLD), which may occur in an asymptomatic form, as simple fatty liver, steatohepatites (NASH), cirrhosis and hepatocellular carcinoma. This disease is associated with dyslipidemia, hypertension, diabetes, metabolic syndrome and insulin resistance. The gold standard for diagnosis is a liver biopsy, considered to be an invasive method. Indirect measures are used to aid its diagnosis, such as physical, biochemical and imaging tests. Objective: Diagnosing NAFLD using MRI as non-invasive method and correlating it with clinical and laboratory findings. Methodology: A cross-sectional study of 50 children and adolescents followed at the Obesity clinic of the University Hospital, FMRP-USP. A questionnaire about personal and family history was aplplied and each subject was submitted to physical examination, laboratory tests (lipip profile, transaminases, glycemia and basal insulin) and magnetic resonance imaging (MRI) of the abdomen for calculation of hepatic, visceral and subcutaneous fat. Results: Fatty liver disease was diagnosed in 14 (28%) of the participants, 8 of them with severe steatosis (fat percentage > 18%) and 4 with milder steatosis (fat percentage between 9 and 18%). There was a statistically significant difference between the hepatic fat detected by MRI and male gender, triglycerides, AST, ALT, AST/ALT ratio and acanthosis nigricans. The calculation of the Homeostasis Model Assessment Insulin Resistance (HOMA-IR) and of the metabolic syndrome did not show a positive relationship with the percentage of hepatic fat. Conclusion: The frequency of hepatic steatosis using MRI as a diagnostic tool, was lower than the values reported in the literature. Among the parameters studied, the best predictors of liver steatosis were triglycerides, AST, ALT, AST/ALT ratio, male gender, acanthosis nigricans and Z score for high body mass index

Cheng, Suosuo. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 159-173). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts aslo in English.