Non-invasive hepatic fat quantification: Can multi-echo Dixon help?

Objective: To evaluate the diagnostic accuracy of multi-echo Dixon magnetic resonance imaging (MRI) in hepatic fat quantification, in comparison with that of magnetic resonance spectroscopy (MRS), on 3.0-T MRI. Materials and Methods: Fifty-five adults with no known liver disease underwent MRI in a 3.0-T scanner for determination of the hepatic fat fraction, with two techniques: multi-echo Dixon, in a manually drawn region of interest (ROI) and in the entire liver parenchyma (automated segmentation); and MRS. The diagnostic accuracy and cutoff value for multi-echo Dixon were determined, with MRS being used as the reference standard. Results: The mean fat fraction obtained by multi-echo Dixon in the manually drawn ROI and in the entire liver was 5.2 ± 5.8% and 6.6 ± 5.2%, respectively, whereas the mean hepatic fat fraction obtained by MRS was 5.7 ± 6.4%. A very strong positive correlation and good agreement were observed between MRS and multi-echo Dixon, for the ROI (r = 0.988, r2 = 0.978, p < 0.001) and for the entire liver parenchyma (r = 0.960, r2 = 0.922, p < 0.001). A moderate positive correlation was observed between the hepatic fat fraction and body mass index of the participants, regardless of the fat estimation technique employed. Conclusion: For hepatic fat quantification, multi-echo Dixon MRI demonstrated a very strong positive correlation and good agreement with MRS (often considered the gold-standard noninvasive technique). Because multi-echo Dixon MRI is more readily available than is MRS, it can be used as a rapid tool for hepatic fat quantification, especially when the hepatic fat distribution is not homogeneous.

Objetivo: Avaliar a acurácia diagnóstica da técnica multieco Dixon na quantificação da gordura hepática em comparação com a espectroscopia por ressonância magnética (ERM), em exames de RM 3.0-T. Materiais e Métodos: Cinquenta e cinco participantes adultos sem doença hepática conhecida foram submetidos a RM 3.0-T para determinação da fração de gordura hepática, usando duas técnicas: multieco Dixon (em ROI desenhada manualmente e em segmentação automatizada para todo o parênquima hepático) e ERM. A precisão diagnóstica e o valor de corte para multieco Dixon foram determinados usando a ERM como padrão de referência. Resultados: A fração de gordura média usando multieco Dixon na ROI desenhada manualmente e na segmentação automatizada do fígado inteiro foi 5,2 ± 5,8% e 6,6 ± 5,2%, respectivamente. A fração de gordura hepática média usando ERM foi 5,7 ± 6,4%. Correlação positiva muito alta e forte concordância foram observadas entre ERM e multieco Dixon, tanto para ROI (r = 0,988, r2 = 0,978, p < 0,001) quanto para todo o parênquima hepático (r = 0,960, r2 = 0,922, p < 0,001). Correlação positiva moderada foi observada entre a fração de gordura hepática e o índice de massa corpórea dos participantes usando ambas as técnicas de estimativa de gordura. Conclusão: Multieco Dixon demonstrou correlação positiva muito alta e concordância com a ERM (muitas vezes considerada padrão de referência não invasivo) para quantificação de gordura hepática. Uma vez que o multieco Dixon está mais prontamente disponível do que a ERM, pode ser usado como uma ferramenta rápida para a quantificação da gordura hepática, especialmente na distribuição não homogênea da gordura.

Non-invasive hepatic fat quantification: Can multi-echo Dixon help? / Quantificação da gordura hepática não invasiva: multieco Dixon pode ajudar?

Abstract Objective: To evaluate the diagnostic accuracy of multi-echo Dixon magnetic resonance imaging (MRI) in hepatic fat quantification, in comparison with that of magnetic resonance spectroscopy (MRS), on 3.0-T MRI. Materials and Methods: Fifty-five adults with no known liver disease underwent MRI in a 3.0-T scanner for determination of the hepatic fat fraction, with two techniques: multi-echo Dixon, in a manually drawn region of interest (ROI) and in the entire liver parenchyma (automated segmentation); and MRS. The diagnostic accuracy and cutoff value for multi-echo Dixon were determined, with MRS being used as the reference standard. Results: The mean fat fraction obtained by multi-echo Dixon in the manually drawn ROI and in the entire liver was 5.2 ± 5.8% and 6.6 ± 5.2%, respectively, whereas the mean hepatic fat fraction obtained by MRS was 5.7 ± 6.4%. A very strong positive correlation and good agreement were observed between MRS and multi-echo Dixon, for the ROI (r = 0.988, r2 = 0.978, p < 0.001) and for the entire liver parenchyma (r = 0.960, r2 = 0.922, p < 0.001). A moderate positive correlation was observed between the hepatic fat fraction and body mass index of the participants, regardless of the fat estimation technique employed. Conclusion: For hepatic fat quantification, multi-echo Dixon MRI demonstrated a very strong positive correlation and good agreement with MRS (often considered the gold-standard noninvasive technique). Because multi-echo Dixon MRI is more readily available than is MRS, it can be used as a rapid tool for hepatic fat quantification, especially when the hepatic fat distribution is not homogeneous.

Resumo Objetivo: Avaliar a acurácia diagnóstica da técnica multieco Dixon na quantificação da gordura hepática em comparação com a espectroscopia por ressonância magnética (ERM), em exames de RM 3.0-T. Materiais e Métodos: Cinquenta e cinco participantes adultos sem doença hepática conhecida foram submetidos a RM 3.0-T para determinação da fração de gordura hepática, usando duas técnicas: multieco Dixon (em ROI desenhada manualmente e em segmentação automatizada para todo o parênquima hepático) e ERM. A precisão diagnóstica e o valor de corte para multieco Dixon foram determinados usando a ERM como padrão de referência. Resultados: A fração de gordura média usando multieco Dixon na ROI desenhada manualmente e na segmentação automatizada do fígado inteiro foi 5,2 ± 5,8% e 6,6 ± 5,2%, respectivamente. A fração de gordura hepática média usando ERM foi 5,7 ± 6,4%. Correlação positiva muito alta e forte concordância foram observadas entre ERM e multieco Dixon, tanto para ROI (r = 0,988, r2 = 0,978, p < 0,001) quanto para todo o parênquima hepático (r = 0,960, r2 = 0,922, p < 0,001). Correlação positiva moderada foi observada entre a fração de gordura hepática e o índice de massa corpórea dos participantes usando ambas as técnicas de estimativa de gordura. Conclusão: Multieco Dixon demonstrou correlação positiva muito alta e concordância com a ERM (muitas vezes considerada padrão de referência não invasivo) para quantificação de gordura hepática. Uma vez que o multieco Dixon está mais prontamente disponível do que a ERM, pode ser usado como uma ferramenta rápida para a quantificação da gordura hepática, especialmente na distribuição não homogênea da gordura.

Interplay between Heart Disease and Metabolic Steatosis: A Contemporary Perspective.

The liver-heart axis is a growing field of interest owing to rising evidence of complex bidirectional interplay between the two organs. Recent data suggest non-alcoholic fatty liver disease (NAFLD) has a significant, independent association with a wide spectrum of structural and functional cardiac diseases, and seems to worsen cardiovascular disease (CVD) prognosis. Conversely, the effect of cardiac disease on NAFLD is not well studied and data are mostly limited to cardiogenic liver disease. We believe it is important to further investigate the heart-liver relationship because of the tremendous global health and economic burden the two diseases pose, and the impact of such investigations on clinical decision making and management guidelines for both diseases. In this review, we summarize the current knowledge on NAFLD diagnosis, its systemic manifestations, and associations with CVD. More specifically, we review the pathophysiological mechanisms that govern the interplay between NAFLD and CVD and evaluate the relationship between different CVD treatments and NAFLD progression.

Pediatric non-alcoholic fatty liver disease: Recent solutions, unresolved issues, and future research directions.

Non-alcoholic fatty liver disease (NAFLD) in children is becoming a major health concern. A "multiple-hit" pathogenetic model has been suggested to explain the progressive liver damage that occurs among children with NAFLD. In addition to the accumulation of fat in the liver, insulin resistance (IR) and oxidative stress due to genetic/epigenetic background, unfavorable lifestyles, gut microbiota and gut-liver axis dysfunction, and perturbations of trace element homeostasis have been shown to be critical for disease progression and the development of more severe inflammatory and fibrotic stages [non-alcoholic steatohepatitis (NASH)]. Simple clinical and laboratory parameters, such as age, history, anthropometrical data (BMI and waist circumference percentiles), blood pressure, surrogate clinical markers of IR (acanthosis nigricans), abdominal ultrasounds, and serum transaminases, lipids and glucose/insulin profiles, allow a clinician to identify children with obesity and obesity-related conditions, including NAFLD and cardiovascular and metabolic risks. A liver biopsy (the "imperfect" gold standard) is required for a definitive NAFLD/NASH diagnosis, particularly to exclude other treatable conditions or when advanced liver disease is expected on clinical and laboratory grounds and preferably prior to any controlled trial of pharmacological/surgical treatments. However, a biopsy clearly cannot represent a screening procedure. Advancements in diagnostic serum and imaging tools, especially for the non-invasive differentiation between NAFLD and NASH, have shown promising results, e.g., magnetic resonance elastography. Weight loss and physical activity should be the first option of intervention. Effective pharmacological treatments are still under development; however, drugs targeting IR, oxidative stress, proinflammatory pathways, dyslipidemia, gut microbiota and gut liver axis dysfunction are an option for patients who are unable to comply with the recommended lifestyle changes. When morbid obesity prevails, bariatric surgery should be considered.