Radiology, University Medical Center Groningen and University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands.
Eur Radiol. 2009 Nov;19(11):2594-607. doi: 10.1007/s00330-009-1470-y. Epub 2009 Jun 6.
MRI, as a completely noninvasive technique, can provide quantitative assessment of perfusion, diffusion, viscoelasticity and metabolism, yielding diverse information about liver function. Furthermore, pathological accumulations of iron and lipids can be quantified. Perfusion MRI with various contrast agents is commonly used for the detection and characterization of focal liver disease and the quantification of blood flow parameters. An extended new application is the evaluation of the therapeutic effect of antiangiogenic drugs on liver tumours. Novel, but already widespread, is a histologically validated relaxometry method using five gradient echo sequences for quantifying liver iron content elevation, a measure of inflammation, liver disease and cancer. Because of the high perfusion fraction in the liver, the apparent diffusion coefficients strongly depend on the gradient factors used in diffusion-weighted MRI. While complicating analysis, this offers the opportunity to study perfusion without contrast injection. Another novel method, MR elastography, has already been established as the only technique able to stage fibrosis or diagnose mild disease. Liver fat content is accurately determined with multivoxel MR spectroscopy (MRS) or by faster MRI methods that are, despite their widespread use, prone to systematic error. Focal liver disease characterisation will be of great benefit once multivoxel methods with fat suppression are implemented in proton MRS, in particular on high-field MR systems providing gains in signal-to-noise ratio and spectral resolution.
MRI 作为一种完全无创的技术，可以提供灌注、扩散、粘弹性和代谢的定量评估，提供有关肝功能的多种信息。此外，还可以定量检测铁和脂质的病理性堆积。各种对比剂的灌注 MRI 常用于检测和描述局灶性肝病，并量化血流参数。一个扩展的新应用是评估抗血管生成药物对肝肿瘤的治疗效果。一种新的但已经广泛应用的方法是使用五个梯度回波序列进行组织学验证的弛豫率测量法，用于定量肝铁含量升高，这是炎症、肝病和癌症的一个指标。由于肝脏的灌注分数较高，表观扩散系数强烈依赖于扩散加权 MRI 中使用的梯度因子。虽然这使得分析变得复杂，但它提供了无需对比注射即可研究灌注的机会。另一种新方法，磁共振弹性成像，已经成为唯一能够分期纤维化或诊断轻度疾病的技术。多体素磁共振波谱（MRS）或更快的 MRI 方法可以准确确定肝内脂肪含量，尽管这些方法得到了广泛应用，但容易出现系统误差。一旦在质子 MRS 中实施带有脂肪抑制的多体素方法，特别是在提供信噪比和光谱分辨率增益的高场 MRI 系统上，局灶性肝病的特征描述将非常有益。
