Varghese Tomy, Techavipoo Udomchai, Liu Wu, Zagzebski James A, Chen Quan, Frank Gary, Lee Fred T
Department of Medical Physics, The University of Wisconsin-Madison, 1530 Medical Sciences Center, 1300 University Ave., Madison, WI 53706, USA.
AJR Am J Roentgenol. 2003 Sep;181(3):701-7. doi: 10.2214/ajr.181.3.1810701.
Elastography is a promising tool for visualizing the zone of necrosis in liver tissue resulting from radiofrequency tumor ablation. Because heat-ablated tissues are stiffer than normal untreated tissue, elastography may prove useful for following up patients who undergo radiofrequency ablative therapy. We sought to report the initial evaluations of the reliability of elastography for delineating thermal lesion boundaries in liver tissue by comparing lesion dimensions determined by elastography with the findings at whole-mount pathology.
Radiofrequency ablation was performed in vitro on liver tissue specimens encased in gelatin phantoms. The imaging plane for elastography was perpendicular to the axis of the radiofrequency electrode so that the ablated region was around the center of the plane. To obtain three-dimensional visualization of thermal lesions, we reconstructed the lesions from multiple elastograms by linearly translating the elastographic scanning plane. Pathology photographs were obtained in the same image plane used for elastography by slicing through the gelatin and tissue phantom using external markers. We used digitized gross pathology photographs obtained at a specified slice thickness to compute the areas and volumes of the lesions. These measurements were then compared to the measurements obtained from the elastograms.
In a sample of 40 thermal lesions, we obtained a correlation between in vitro elastographic and pathologic measurements of r = 0.9371 (p < 0.00001) for area estimates and r = 0.979 (p < 0.00001) for volume estimates.
We found excellent correlation between the measurements of the dimensions, areas, and volumes of thermal lesions that were based on elastographic images and the measurements that were based on digitized pathologic images. When compared with digitized pathologic measurements, elastographic measurements showed a tendency to slightly underestimate both the areas and volumes of lesions. Nevertheless, elastography is a reliable technique for delineating thermal lesions resulting from radiofrequency ablation.
弹性成像技术是一种很有前景的工具，可用于可视化射频肿瘤消融导致的肝组织坏死区域。由于热消融组织比未处理的正常组织更硬，弹性成像技术可能对接受射频消融治疗的患者的随访有用。我们试图通过比较弹性成像确定的病变尺寸与全层病理学结果，报告弹性成像在描绘肝组织热损伤边界方面可靠性的初步评估。
在体外对包裹在明胶模型中的肝组织标本进行射频消融。弹性成像的成像平面垂直于射频电极轴，以便消融区域位于平面中心周围。为了获得热损伤的三维可视化，我们通过线性平移弹性成像扫描平面，从多个弹性图重建损伤。通过使用外部标记物切开明胶和组织模型，在与弹性成像相同的图像平面上获取病理照片。我们使用在指定切片厚度下获得的数字化大体病理照片来计算损伤的面积和体积。然后将这些测量值与从弹性图获得的测量值进行比较。
在40个热损伤样本中，我们获得了体外弹性成像与病理测量之间的相关性，面积估计的r = 0.9371（p < 0.00001），体积估计的r = 0.979（p < 0.00001）。
我们发现基于弹性成像图像的热损伤尺寸、面积和体积测量值与基于数字化病理图像的测量值之间具有极好的相关性。与数字化病理测量相比，弹性成像测量显示出略微低估损伤面积和体积的趋势。尽管如此，弹性成像是描绘射频消融导致的热损伤的可靠技术。
