Seiderer M, Wagner H, Stäbler A, Fink U
Institut für Radiologische Diagnostik, Ludwig-Maximilians-Universität München.
Rofo. 1994 May;160(5):453-8. doi: 10.1055/s-2008-1032457.
Gradient-echo (GE) imaging with repetition times equivalent to those of T1-weighted spin-echo (SE) sequences and echo times for antiphase (opposed) transverse magnetisation have proved to be sensitive for high contrast imaging of focal lesions of red bone marrow. The sensitivity of antiphase GE sequences is due to the chemical shift between water-bound and fat-bound protons which introduces a tissue parameter that is not accessible by SE sequences. Main advantage of these GE sequences is the low signal intensity of intact red marrow and the high signal intensity of tumours and inflammatory lesions which allows, similar to T2-weighted SE sequences, for positive contrast imaging of lesions. In order to evaluate and to optimise the contrast-to-noise ratio (CNR) for red bone marrow and tumour 200 GE and 40 SE sequences with repetition times (TR) between 100 and 900 ms, echo times (TE) between 14 and 21 ms and flip angles (alpha) between 10 and 90 degrees were studied. CNR was measured and optimized regarding TR, TE, and alpha. The results indicate that opposed GE sequences, relatively independent from TR and alpha, are characterized by a high contrast-to-noise ratio. According to their high sensitivity for lesion detection they are suited to replace T2-weighted SE sequences.
梯度回波（GE）成像的重复时间与T1加权自旋回波（SE）序列相当，且具有反相位（相反）横向磁化的回波时间，已被证明对红骨髓局灶性病变的高对比度成像很敏感。反相位GE序列的敏感性源于水结合质子和脂肪结合质子之间的化学位移，这引入了一个SE序列无法获取的组织参数。这些GE序列的主要优点是完整红骨髓的低信号强度以及肿瘤和炎性病变的高信号强度，这与T2加权SE序列类似，允许对病变进行阳性对比成像。为了评估和优化红骨髓与肿瘤的对比噪声比（CNR），研究了200个GE序列和40个SE序列，其重复时间（TR）在100至900毫秒之间，回波时间（TE）在14至21毫秒之间，翻转角（α）在10至90度之间。测量了CNR，并针对TR、TE和α进行了优化。结果表明，相对独立于TR和α的反相位GE序列具有高对比噪声比。根据它们对病变检测的高敏感性，它们适合替代T2加权SE序列。
