Imaging of nonalcoholic fatty liver disease and its clinical utility

Abstract

The prevalence of nonalcoholic fatty liver disease has been continuously rising over the last three decades and is projected to become the most common indication for liver transplantation in the near future. Its pathophysiology and complex interplay with diabetes and the metabolic syndrome are not as yet fully understood despite growing scientific interest and research. Modern imaging techniques offer significant assistance in this field by enabling the study of the liver noninvasively and evaluation of the degree of both steatosis and fibrosis, and even in attempting to diagnose the presence of inflammation (steatohepatitis). The derived measurements are highly precise, accurate and reproducible, performing better than biopsy in terms of quantification. In this article, these imaging techniques are overviewed and their performance regarding diagnosis, stratification and monitoring are evaluated. Their expanding role both in the research arena and in clinical practice along with their limitations is also discussed.

Negative Energy Balance Induced by Exercise or Diet: Effects on Visceral Adipose Tissue and Liver Fat

“…Ultrasonography is limited as a single diagnostic tool because of the lack of sufficient sensitivity [6,24,25]. Accuracy of an ultrasound decreases with increasing body mass index [26][27][28]. Magnetic resonance spectroscopy (MRS) is cited as the gold standard MR technique to quantify LF.…”

“…There is a high level of accuracy and reproducibility with this method, however, it is limited in availability because of the high degree of skill and specialized software required. Similar to liver biopsies, only a portion of the liver is analyzed, and so, sampling errors may occur [26].…”

Imaging Biomarkers for Nonalcoholic Fatty Liver Disease

“…Therefore, its sensitivity and specificity are as high as 96% and 100%, respectively, for quantifying any degree of fatty liver. PDFF is reliable and reproducible across different MR scanners and highly correlates with histology in patients with NAFLD (17). This MR technique is FDA approved and is available on most MRI scanners from different manufacturers.…”

Efeito do emagrecimento nos parâmetros ultrassonográficos modo B e Doppler colorido do fígado e veia hepática direita de cadelas obesas

“…No entanto, a ultrassonografia modo B possui algumas desvantagens, como a incapacidade de se estimar quantitativamente a gordura hepática e de diferenciar quadros de esteatose e fibrose (SCHWENZER et al, 2009). Além do mais, pode-se considerá-la subjetiva, por ser um exame diagnóstico operador dependente (CHARTAMPILAS, 2018;SAADEH et al, 2002;SCHWENZER et al, 2009) (BOLONDI et al, 1991;COLLI et al, 2003).…”

“…Além disso, é interessante que a região de interesse seja delimitada, quando possível, no mesmo plano sonográfico e, a partir de então, alguns parâmetros podem ser calculados para cada órgão, tais como: circunferência e área, nível de brilho total, nível de brilho médio, nível de brilho mais frequente, desvio padrão (dp) e histograma(WEBB et al, 2009). RM, por sua vez, tem sido relatada como o método de maior acurácia no diagnóstico de esteatose hepática, pois possibilita a detecção de gordura em locais específicos(AWAI et al, 2014;CHARTAMPILAS, 2018). Essa técnica se baseia em picos de ressonância de água e gordura, enquanto a água possui um único pico, a gordura possui diversos espectros de ressonância.…”