用于肝炎症中粘弹性模型识别的人体肝与脾超宽带磁共振弹性成像
Ultra-wideband MRE of the human liver and spleen for viscoelastic model identification in hepatic inflammation
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中文总结 AI 辅助
本研究开发覆盖5-80 Hz的超宽带MRE，经9名健康志愿者和9名炎症性肝病患者验证，识别出肝炎症在低频下的粘弹性变化及流变模型特征，为肝病诊断提供新手段。
中文摘要 AI 辅助
磁共振弹性成像（MRE）已被确立为肝纤维化的非侵入性评估手段。传统腹部MRE通常局限于40-60 Hz的频率范围，低频段（尤其针对肝炎症）仍未得到充分探索。本研究开发了覆盖5-80 Hz的超宽带MRE，以探究肝与脾的频率分辨粘弹性色散特性，并识别肝炎症的生物力学标志物。经体模验证后，对9名健康志愿者和9名炎症性肝病患者在12个频率下进行检查，采用时空相位解缠和频率自适应波场预处理，重建剪切波速度（SWS）、穿透率（PR）和损耗角（φ），并评估6种流变模型。炎症相关的最大变化出现在20 Hz以下：φ升高63%（p<0.001），PR降低37%（p=0.003），SWS升高8%（p=0.008），提示变化主要与耗散相关而非刚度相关，且在低频段呈现向流体样行为的转变，仅伴随微小刚度变化。串联阻尼器的流变弹簧壶模型拟合效果最佳，且肝与脾呈现不同的色散函数。患者的弹簧壶弹性模量升高101%（p=0.001），而粘度和弹簧壶幂律指数分别降低52%（p=0.002）和58%（p<0.001），提示肝特性从软流体向硬固体转变。超宽带MRE显示，炎症性肝病与低频下更强耗散和流体样行为的特性转变相关，而在高频下呈现固体样行为；超低频MRE或可提供炎症相关肝粘弹性的诊断窗口，无需完整流变建模。
英文摘要
Magnetic resonance elastography (MRE) is established for noninvasive assessment of liver fibrosis. Conventional abdominal MRE is typically limited to 40-60 Hz. Lower frequencies remain largely unexplored, particularly with regard to hepatic inflammation. We developed ultra-wideband MRE covering 5-80 Hz to investigate frequency-resolved viscoelastic dispersion of the liver and spleen and to identify biomechanical markers of hepatic inflammation. Following phantom validation, nine healthy volunteers and nine patients with inflammatory liver disease were examined at 12 frequencies. Spatiotemporal phase unwrapping and frequency-adaptive wavefield preprocessing enabled reconstruction of shear wave speed (SWS), penetration rate (PR), and loss angle ($ϕ$). Six rheological models were evaluated. The largest inflammation-associated changes were observed at frequencies below 20 Hz: $ϕ$ increased by 63% (p<0.001), PR decreased by 37% (p=0.003), and SWS increased by 8% (p=0.008), indicating predominantly dissipative, rather than stiffness-related, changes and a shift toward fluid-like behavior with minor stiffness changes in the lower frequency regime. The rheological springpot model with serial dashpot provided the best fit and revealed distinct dispersion functions for liver and spleen. In patients, springpot elastic modulus increased (101%, p=0.001), while viscosity and springpot power-law exponent decreased (52%, p=0.002 and 58%, p<0.001) suggesting a shift from soft-fluid to stiff-solid liver properties. Ultra-wideband MRE revealed that inflammatory liver disease is associated with property shifts toward stronger dissipation and fluid-like behavior at low frequencies while displaying solid-like behavior at higher frequencies. Ultra-low frequency MRE may provide a diagnostic window into inflammation-associated liver viscoelasticity without full rheological modeling.
