Feasibility of histogram analysis of susceptibility-weighted MRI for staging of liver fibrosis

Autor: Xin Xing Hu, Shan Yang, Zhao Xia Yang, Ying Ding, He Yue Liang, Meng Su Zeng, Ya Qin Huang, Sheng-Xiang Rao
Rok vydání: 2016
Předmět:
Zdroj: Diagnostic and Interventional Radiology. 22:301-307
ISSN: 1305-3612
1305-3825
Popis: Liver fibrosis is the accumulation of extracellular matrix proteins and is a feature of most chronic liver diseases (CLDs) (1). Studies have demonstrated that fibrosis is reversible at early stages (2, 3), and causal treatments improve liver function (4). Because of the great risk of liver cirrhosis, hepatocellular carcinoma (HCC), and other complications in patients with liver fibrosis, accurate assessment of the liver fibrosis stage and early detection of early cirrhosis are important for judging the prognosis and planning treatment (5). Furthermore, the severity of fibrosis has been associated with remnant liver functional reserve after hepatectomy for HCC (6). A noninvasive tool that would enable us to preoperatively evaluate the severity of liver fibrosis would be beneficial for a more risk-adapted treatment strategy. Liver biopsy is commonly considered to be the gold standard for grading liver fibrosis; however, biopsy is considered impractical for evaluating disease progression or response to treatment because of its invasiveness, interobserver variability, sample errors, patients’ acceptance, and complications such as bleeding, infection, and pain (7–10). Consequently, a noninvasive and feasible method for assessing the liver fibrosis stage is required. Conventional axial imaging techniques have limited value for evaluating liver fibrosis. Recently, several noninvasive methods have been assessed, including laboratory tests, ultrasound transient elastography (11), and magnetic resonance imaging (MRI)-based techniques (e.g., magnetic elastography, diffusion-weighted imaging [DWI], perfusion, gadoxetic acid-enhanced MRI, and susceptibility-weighted imaging [SWI]) (12–21). SWI was demonstrated to be feasible for abdominal imaging and could utilize phase information to enhance susceptibility effects that were caused by iron in cirrhosis and HCC (22, 23). In theory, increased iron content of the liver and secondary changes manifesting in progressive collagen deposition are important background alterations in the development of liver fibrosis (24). Balassy et al. (21) reported that by measuring the mean values of signal intensities and using a corrected liver-to-muscle ratio, SWI might be used as an alternative technique to assess the severity of hepatic fibrosis. However, they did not consider the heterogeneity of fibrotic liver parenchyma. Image texture is a sensitive characteristic for assessing pathology, and texture analysis is a method that can provide more information regarding the image texture features that may be ignored by visual evaluation (25). A histogram is a useful tool in hepatic texture analysis for depicting the distribution of signal intensity levels (26), which can reflect the heterogeneity of pathologic changes. Kim et al. (27) demonstrated that histogram analysis of gadoxetic acid-enhanced hepatobiliary phase MRI could be useful in depicting enhancement heterogeneity, which is representative of the liver fibrosis stage (27). We hypothesized that the fibrotic liver had different heterogeneities of iron deposition and secondary changes in different fibrosis stages, which might be detected by histogram analyses of SWI. Thus, we aimed to evaluate whether histogram analysis of SWI could quantify liver fibrosis stages and assess whether different echo times (TEs) of SWI could affect the quantification of SWI histogram analyses.
Databáze: OpenAIRE
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