Group of Radiation Biology and Tumor Physiology, Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Norway.
Acta Oncol. 2011 Apr;50(3):427-34. doi: 10.3109/0284186X.2010.526633. Epub 2010 Oct 18.
The prognostic and predictive value of magnetic resonance (MR) investigations in clinical oncology may be improved by implementing strategies for discriminating between viable and necrotic tissue in tumors. The purpose of this preclinical study was to investigate whether the extent of necrosis in tumors can be assessed by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and/or T(2)-weighted MR imaging.
Three amelanotic human melanoma xenograft lines differing substantially in tumor necrotic fraction, necrotic pattern, extracellular volume fraction, and blood perfusion were used as experimental models of human cancer. MRI was performed at 1.5 T and a spatial resolution of 0.23 × 0.47 × 2.0 mm(3). Gadolinium diethylene-triamine penta-acetic acid (Gd-DTPA) was used as contrast agent. Plots of Gd-DTPA concentration versus time were generated for each voxel, and three parameters were calculated for each curve: the extracellular volume fraction (ν(e)), the final slope (a), and the Gd-DTPA concentration at one minute after the contrast administration (C(1min)). Parametric images of ν(e), a, C(1min), and the signal intensity in T(2)-weighted images (SI(T2W)) were compared with the histology of the imaged tissue.
The ν(e), a, and C(1min) frequency distributions were significantly different for necrotic and viable tissue in all three tumor lines. By using adequate values of ν(e), a, and C(1min) to discriminate between necrotic and viable tissue, significant correlations were found between the fraction of necrotic tissue assessed by MRI and the fraction of necrotic tissue assessed by image analysis of histological preparations. On the other hand, the SI(T2W) frequency distributions did not differ significantly between necrotic and viable tissue in two of the three tumor lines.
Necrotic regions in tumor tissue can be identified in parametric images derived from DCE-MRI series, whereas T(2)-weighted images are unsuitable for detection of tumor necrosis.
在临床肿瘤学中，通过实施区分肿瘤中存活组织和坏死组织的策略，磁共振（MR）检查的预后和预测价值可能会得到提高。本临床前研究的目的是探讨肿瘤的坏死程度是否可以通过动态对比增强磁共振成像（DCE-MRI）和/或 T2 加权磁共振成像来评估。
使用三种黑色素瘤异种移植系作为人类癌症的实验模型，这些异种移植系在肿瘤坏死部分、坏死模式、细胞外体积分数和血液灌注方面有很大差异。MRI 在 1.5T 和 0.23×0.47×2.0mm3 的空间分辨率下进行。使用钆二乙三胺五乙酸（Gd-DTPA）作为对比剂。为每个体素生成 Gd-DTPA 浓度与时间的关系图，并为每个曲线计算三个参数：细胞外体积分数（ν(e)）、最终斜率（a）和 Gd-DTPA 浓度在对比剂给药后一分钟（C(1min)）。ν(e)、a、C(1min)和 T2 加权图像（SI(T2W)）的信号强度的参数图像与成像组织的组织学进行了比较。
在所有三种肿瘤系中，坏死组织和存活组织的ν(e)、a 和 C(1min)频率分布均有显著差异。通过使用适当的 ν(e)、a 和 C(1min)值来区分坏死组织和存活组织，在 MRI 评估的坏死组织与组织学切片图像分析评估的坏死组织之间发现了显著的相关性。另一方面，在三种肿瘤系中的两种肿瘤系中，坏死组织和存活组织的 SI(T2W)频率分布没有显著差异。
可以从 DCE-MRI 系列衍生的参数图像中识别肿瘤组织中的坏死区域，而 T2 加权图像不适合检测肿瘤坏死。
