Liver steatosis is the most common chronic liver disease and affects 10–24% of the general population. As the grade of disease can range from fat infiltration to steatohepatitis and cirrhosis, an early diagnosis is needed to set the most appropriate therapy. Innovative noninvasive radiological techniques have been developed through MRI and US. MRI-PDFF is the reference standard, but it is not so widely diffused due to its cost. For this reason, ultrasound tools have been validated to study liver parenchyma. The qualitative assessment of the brightness of liver parenchyma has now been supported by quantitative values of attenuation and scattering to make the analysis objective and reproducible. We aim to demonstrate the reliability of quantitative ultrasound in assessing liver fat and to confirm the inter-operator reliability in different respiratory phases. We enrolled 45 patients examined during normal breathing at rest, peak inspiration, peak expiration, and semi-sitting position. The highest inter-operator agreement in both attenuation and scattering parameters was achieved at peak inspiration and peak expiration, followed by semi-sitting position. In conclusion, this technology also allows to monitor uncompliant patients, as it grants high reliability and reproducibility in different body position and respiratory phases.

肝脂肪变性是最常见的慢性肝病，影响 10-24% 的普通人群。由于疾病的程度可以从脂肪浸润到脂肪性肝炎和肝硬化，因此需要早期诊断以制定最合适的治疗方法。通过 MRI 和 US 开发了创新的无创放射技术。 MRI-PDFF 是参考标准，但由于其成本原因并未得到广泛普及。因此，超声工具已被验证可用于研究肝实质。肝实质亮度的定性评估现已得到衰减和散射定量值的支持，使分析客观且可重复。我们的目的是证明定量超声在评估肝脏脂肪方面的可靠性，并确认不同呼吸阶段操作者之间的可靠性。我们招募了 45 名患者，他们在休息时的正常呼吸、吸气峰值、呼气峰值和半坐位期间进行了检查。衰减和散射参数的操作者间一致性最高是在吸气峰值和呼气峰值时实现的，其次是半坐位。总之，该技术还可以监测不依从的患者，因为它在不同的体位和呼吸阶段具有高可靠性和可重复性。