MR TECHNOLOGY - EFFECT OF EVEN-ECHO REPHASING ON CALCULATED T2 VALUES AND T2 IMAGES
MR TECHNOLOGY - EFFECT OF EVEN-ECHO REPHASING ON CALCULATED T2 VALUES AND T2 IMAGES
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DOI：
10.1148/radiology.157.1.4034984
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发表时间：
1985-01-01
期刊：
影响因子：
19.7
通讯作者：
NORMAN, D
中科院分区：
文献类型：
--
作者：
KUCHARCZYK, W;BRANTZAWADZKI, M;NORMAN, D
在血流的多个自旋回波图像序列中，“均匀回波”现象产生了从具有缓慢血流的正常血管的第一回波图像到第二回波图像的信号幅度的绝对增加。将其与静止组织的病理病灶在二次回波图像上可见的明显相对较高的信号强度区分开来，对诊断医生很重要。回顾性审查了包含两种组织类型的选定[人类]病例材料：已知具有慢血流的组织，如正常静脉和静脉窦和血管畸形，以及具有长横向（T2）弛豫时间并在二次回波图像上显示为密集结构的组织，如肿瘤、梗死和脱髓鞘区域。通过计算机对定义的感兴趣区域进行T2参数的计算。还生成了T2图像。对所采集图像的目视检查不能可靠地区分由于均匀回波重新定相而导致的强度增加与第二回波图像上看到的相邻组织之间的相对变化。通过计算T2值和计算机合成T2图像（代表采集的双回波序列强度数据），可更明确区分均匀回波现象。当T2值延长的静止组织邻近或接近血管或血管病变时，合成图像特别有用。一个五自旋回波图像序列是有价值的分离缓慢流动的静止组织的技术，合成T2差分图像使用三个连续的回波。
In multiple spin-echo image sequences of blood flow, the "even-echo" phenomenon produces an absolute increase in signal magnitude from first- to second-echo images of normal vessels haboring slow flow. Distinguishing this from the apparent relatively high signal intensity seen on second-echo images in pathologic foci of stationary tissue is important to the diagnostician. Selected [human] case material containing two tissue types was reviewed retrospectively: tissues known to harbor slow flow, such as normal veins and venous sinuses and vascular malformations, and tissues that have long transverse (T2) relaxation times and appear as intense structures on second-echo images, such as neoplasms, infarcts, and regions of demyelination. Calculations of T2 parameters were made by computer for defined regions of interest. T2 images were also generated. Visual inspection of the acquired images did not reliably distinguish increased intensity due to even echo rephasing from the relative changes between adjacent tissues seen on second echo images. More definitive differentiation of the even-echo phenomenon was provided by calculated values of T2 and computer-synthesized T2 images representing acquired intensity data of two-echo sequences. The synthesized images were especially useful when stationary tissue with lengthened T2 values was adjacent to or in proximity to vessels or vascular lesions. A five spin-echo image sequence was valuable for separating slow flow from stationary tissue by a technique of synthesizing T2-difference images using three consecutive echoes.