Salameh Najat, Larrat Benoît, Abarca-Quinones Jorge, Pallu Stéphane, Dorvillius Mylène, Leclercq Isabelle, Fink Mathias, Sinkus Ralph, Van Beers Bernard E
Diagnostic Radiology Unit, and Laboratory of Gastroenterology, Université Catholique de Louvain, St-Luc University Hospital, Brussels, Belgium.
Radiology. 2009 Oct;253(1):90-7. doi: 10.1148/radiol.2523081817. Epub 2009 Jul 8.
To assess the potential value of magnetic resonance (MR) elastographic imaging to help detect nonalcoholic steatohepatitis in the fatty rat liver.
This study was approved by the regional ethics committee. Fifty-four rats were imaged after being fed either a standard diet, a choline-deficient diet for up to 8 weeks to induce steatohepatitis, or a 2-week orotic acid diet to induce steatosis; or were imaged 48 hours after carbon tetrachloride injection to model acute liver injury. MR elastography was performed at 7.0 T to assess viscoelastic liver parameters. Steatosis and fibrosis were quantified with morphometric and biochemical analysis. Myofibroblast activation was assessed with morphometric analysis of alpha-smooth muscle actin. Expression of transforming growth factor beta1 and procollagens 1 and 3 as markers of fibrogenesis was evaluated with real-time reverse transcription polymerase chain reaction. Inflammation was scored at histologic analysis.
In rats with steatohepatitis, mean elasticity (2.24 kPa +/- 0.19 [standard deviation] vs 1.82 kPa +/- 0.22) and mean viscosity (0.86 kPa +/- 0.10 vs 0.59 kPa +/- 0.12) increased significantly (P < .005) after the 2-week orotic acid diet, while steatosis, inflammation, myofibroblast activation, and increase of other fibrogenesis markers were observed. Fibrosis appeared only after 5 weeks. In rats with steatosis, viscosity increased (0.77 kPa +/- 0.11, P < .005), elasticity remained constant. In rats with acute liver injury, elasticity (2.96 kPa +/- 0.63) and viscosity (0.85 kPa +/- 0.22) increased (P < .005), while fibrogenesis and inflammation were observed without substantial fibrosis or steatosis. At multivariate analysis in all rats, liver elasticity correlated only with myofibroblast activation (P < .001, r > 0.6).
The results suggest that in nonalcoholic fatty rat liver, MR elastography may be useful in the early detection of steatohepatitis by showing increased elasticity and appearing before fibrosis development, which was linked to myofibroblast activation.
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.2523081817/-/DC1.
评估磁共振弹性成像在检测脂肪肝大鼠肝脏中非酒精性脂肪性肝炎的潜在价值。
本研究经地区伦理委员会批准。54只大鼠在喂食标准饮食、胆碱缺乏饮食长达8周以诱导脂肪性肝炎、2周乳清酸饮食以诱导脂肪变性后进行成像；或在注射四氯化碳以模拟急性肝损伤48小时后进行成像。在7.0T下进行磁共振弹性成像以评估肝脏粘弹性参数。通过形态学和生化分析对脂肪变性和纤维化进行定量。通过对α-平滑肌肌动蛋白的形态学分析评估肌成纤维细胞活化。用实时逆转录聚合酶链反应评估转化生长因子β1和前胶原1和3作为纤维化标志物的表达。在组织学分析中对炎症进行评分。
在脂肪性肝炎大鼠中，2周乳清酸饮食后平均弹性（2.24kPa±0.19[标准差]对1.82kPa±0.22）和平均粘度（0.86kPa±0.10对0.59kPa±0.12）显著增加（P<.005），同时观察到脂肪变性、炎症、肌成纤维细胞活化以及其他纤维化标志物增加。纤维化仅在5周后出现。在脂肪变性大鼠中，粘度增加（0.77kPa±0.11，P<.005），弹性保持不变。在急性肝损伤大鼠中，弹性（2.96kPa±0.63）和粘度（0.85kPa±0.22）增加（P<.005），同时观察到纤维化和炎症，但无明显纤维化或脂肪变性。在所有大鼠的多变量分析中，肝脏弹性仅与肌成纤维细胞活化相关（P<.001，r>0.6）。
结果表明，在非酒精性脂肪肝大鼠肝脏中，磁共振弹性成像可能通过显示弹性增加且在纤维化发展之前出现，有助于早期检测脂肪性肝炎，这与肌成纤维细胞活化有关。
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.2523081817/-/DC1。
