Reeder S B, Faranesh A Z, Boxerman J L, McVeigh E R
Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Magn Reson Med. 1998 Jun;39(6):988-98. doi: 10.1002/mrm.1910390617.
Cardiac echo-planar imaging suffers invariably from regions of severe distortion and T2 decay in the myocardium. The purpose of this work was to perform local measurements of T2 and field inhomogeneities in the myocardium and to identify the sources of focal signal loss and distortion. Field inhomogeneity maps and T2 were measured in five normal volunteers in short-axis slices spanning from base to apex. It was found that T2 ranged from 26 ms (SD = 7 ms, n = 5) to 41 ms (SD = 11 ms, n = 5) over most of the heart, and peak-to-peak field inhomogeneity differences were 71 Hz (SD = 14 Hz, n = 5). In all hearts, regions of severe signal loss were consistently adjacent to the posterior vein of the left ventricle; T*2 in these regions was 12 ms (SD = 2 ms, n = 5), and the difference in resonance frequency with the surrounding myocardium was 70-100 Hz. These effects may be caused by increased magnetic susceptibility from deoxygenated blood in these veins.
心脏回波平面成像总是会受到心肌中严重畸变区域和T2衰减的影响。这项工作的目的是对心肌中的T2和场不均匀性进行局部测量，并确定局灶性信号丢失和畸变的来源。在五名正常志愿者中，在从心底到心尖的短轴切片中测量了场不均匀性图和T2。结果发现，在心脏的大部分区域，T2范围为26毫秒（标准差=7毫秒，n=5）至41毫秒（标准差=11毫秒，n=5），峰峰值场不均匀性差异为71赫兹（标准差=14赫兹，n=5）。在所有心脏中，严重信号丢失区域始终与左心室后静脉相邻；这些区域的T*2为12毫秒（标准差=2毫秒，n=5），与周围心肌的共振频率差异为70-100赫兹。这些影响可能是由这些静脉中脱氧血液的磁化率增加引起的。
