Biagini C
Radiol Med. 1986 Jun;72(6):379-92.
Aim of this article is to examine the possibilities and the limits of MR imaging in oncology, with special regard to the tissue characterization of tumors. Basic information is given on the fundamental parameters of MR, and the concept of image contrast is discussed, with a comparison between the image in conventional radiology and in MR. Factors affecting MR parameters and influencing the image contrast are analyzed; they are classified as extrinsic, or connected to the patient's conditions and to technical modalities, and as intrinsic or inherent to biological factors. Intrinsic factors are scheduled in three groups: a) tissue physico-chemical structure; b) functions or physiological conditions; c) pathological aspects. One of the most important factors related with the first group is water content. The possible influences of water content on the measurement of the proton MR relaxation times are numerous and complex. As a first approximation, relaxation times are directly related to water content; nevertheless many experimental results show that this statement is not sufficient to explain the observed variations of relaxation times in different tissues and organs. Some other data are accounted for the presence of different relaxation times of water in the same sample, and for the microtrabecular structure of the cell. In normal tissues and structures, further elements are explained on the basis of simple physico-chemical characteristics. In tumors the increase of T1 and T2 observed in experimental evaluations performed on samples of tissues, was largely confirmed in the images. To an equal extent failure of specificity of the increase of relaxation times of tumors is well documented in experimental research and in clinical experiences. In experimental research a strict comparison was made between the tumor and the tissue of origin. Increase of relaxation parameters appears related to the presence of larger fluid-filled areas, to the diminution of average cell size, and to reduced amount of rough and smooth endoplasmic reticulum. In clinical experiences good results are obtained in the ascertainment of the tumors localization and extension; macroscopic aspects connected to the peritumoral structures, inhomogeneities, and necrosis are well evaluated. New data are acquired in the study of early and late effects of radiation in patients submitted to radiotherapy for various types of tumors.
本文旨在探讨磁共振成像（MR成像）在肿瘤学中的可能性与局限性，尤其关注肿瘤的组织特征。文中给出了有关MR基本参数的基础信息，并讨论了图像对比度的概念，同时对传统放射学图像与MR图像进行了比较。分析了影响MR参数及图像对比度的因素；这些因素分为外在因素，即与患者状况和技术方式相关的因素，以及内在因素，即生物因素所固有的因素。内在因素分为三组：a）组织的物理化学结构；b）功能或生理状况；c）病理方面。与第一组相关的最重要因素之一是含水量。含水量对质子MR弛豫时间测量的可能影响众多且复杂。初步看来，弛豫时间与含水量直接相关；然而，许多实验结果表明，这一说法不足以解释在不同组织和器官中观察到的弛豫时间变化。其他一些数据则解释了同一样品中不同水分子弛豫时间的存在以及细胞的微小梁结构。在正常组织和结构中，基于简单的物理化学特征对其他因素进行了解释。在肿瘤中，对组织样本进行实验评估时观察到的T1和T2增加在图像中得到了很大程度的证实。同样，肿瘤弛豫时间增加缺乏特异性在实验研究和临床经验中也有充分记录。在实验研究中，对肿瘤与其起源组织进行了严格比较。弛豫参数的增加似乎与更大的液性区域的存在、平均细胞大小的减小以及粗面和滑面内质网数量的减少有关。在临床经验中，在确定肿瘤的定位和范围方面取得了良好结果；与肿瘤周围结构、不均匀性和坏死相关的宏观方面得到了很好的评估。在对接受各种肿瘤放疗的患者进行放射治疗的早期和晚期效应研究中获得了新的数据。
