Hydrogen MR imaging of the head at 0.35 T and 0.7 T: effects of magnetic field strength.
Hydrogen MR imaging of the head at 0.35 T and 0.7 T: effects of magnetic field strength.
复制标题
0.35 T 和 0.7 T 下头部的氢 MR 成像：磁场强度的影响。
DOI：
10.1148/radiology.157.3.4059555
复制
发表时间：
1985
期刊：
影响因子：
19.7
通讯作者：
Kaufman,L
中科院分区：
文献类型：
--
作者：
Posin,JP;Arakawa,M;Crooks,LE;Feinberg,DA;Hoenninger,JC;Watts,JC;Mills,CM;Kaufman,L
为了确定0.7T的氢磁共振成像是否比0.35T的氢磁共振成像具有更高的临床价值，在这些场强下获得了各种颅内疾病患者的头部图像。测量组织对比度(C)、信噪比(S/N)、T1和T2弛豫时间。对于给定的具有相同成像时间、分辨率和数据采样窗口的自旋回波序列，乘积C X S/N在较低的场强下略低。在具有等化学位移伪影的成像条件下，0.35T的C×S/N等于或大于0.7T的测量结果。随着场强的增加，病变区和周围正常组织的T1增加，导致相应的绝对信号水平的丧失和对比度的降低。在0.35T和0.7T时，病变同样清晰可见。较高磁场下增加的T1和降低的CX S/N--当使用固定的成像时间、分辨率、化学位移和序列测量时--表明与较低的磁场强度系统相比，这种磁场强度可能不会改善组织对比度、诊断能力或临床吞吐量。
To determine whether hydrogen magnetic resonance imaging at 0.7 T provides added clinical value over imaging at 0.35 T, images of the heads of patients with various intracranial disorders were obtained at these field strengths. Measurements of tissue contrast (C), signal-to-noise (S/N) ratio, and T1 and T2 relaxation times were determined. For a given spin-echo sequence with equal imaging time, resolution, and data sampling window, the product C X S/N was somewhat lower for the lower field strength. Under conditions of imaging with equal chemical shift artifact, C X S/N at 0.35 T was equal to or greater than that measured at 0.7 T. With an increase in field strength, T1 of pathologic areas and surrounding normal tissues increased, resulting in a corresponding loss of absolute signal level and decrease in contrast. Lesions were equally well seen at both 0.35 T and 0.7 T. The increased T1 and decreased C X S/N for higher magnetic fields--when measured with a fixed imaging time, resolution, chemical shift, and sequence--suggest that such field strengths may not improve tissue contrast, diagnostic ability, or clinical throughput when compared with lower field strength systems.