DIMINISHING VARIANCE ALGORITHM RESPIRATORY COMPENSATION FOR FAST SPIN ECHO

快速自旋回波的方差递减算法呼吸补偿

• 批准号: 6282986
• 负责人: WALTER F BLOCK
• 金额: $ 0.37万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 1998-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6282986
• 关键词: Mammalia; bioengineering /biomedical engineering; biomedical resource; magnetic resonance imaging; respiratory system; technology /technique

Introduction: Fast Spin Echo (FSE) is incompatible with ordered phase encoded respiratory compensation. For patients incapable of breath-holds or when additional SNR or resolution is desired, signal averaging, respiratory triggering and multiple breath-holds techniques are available. We propose an easily implemented method that requires no patient cooperation. We have modified the diminishing variance algorithm (DVA) to work on long TR, multiple slice sequences without a navigator echo. Methods: We use pneumatic bellows to provide respiratory position information instead of navigator echos. Though navigators are more accurate, navigators leave a signal loss band across the abdomen and require additional processing time. Bellows information is available easily and at a higher sampling rate. During the first pass through the sequence, the respiratory position and its corresponding excitation are stored in a separate histogram for each slice. After completing the first pass, information from all the histograms is used to determine the subject's most common respiratory position (mode). Thereafter, the histogram of each individual slice is narrowed about the mode during a reacquisition period. Prior to each reacquisition excitation, the bellows provide a respiratory position. If this position will narrow the slice's histogram, then the slice's worst excitation is reacquired. The reacquisition period continues until all histograms are sufficiently narrow or the scan reaches a pre-defined time limit. Results: Though DVA and respiratory triggering have similar objectives, DVA guarantees the smallest variance of respiratory positions for a fixed scan time. DVA also allows a consistent TR independent of respiration rate. Conclusions: DVA compensation for FSE reduces motion artifacts while efficiently using scan time. It is easy to implement, works with uncooperative subjects, and does not limit other gating or contrast parameters.

快速自旋回声(FSE)与有序不兼容 相位编码的呼吸补偿。对于无能力的患者 屏息或当需要更高的SNR或分辨率时，信号 平均化、呼吸触发和多次屏气技术 都是可用的。我们提出了一种易于实现的方法，该方法需要 没有耐心的合作。我们已经修正了递减的方差 算法(DVA)，用于处理长TR、多切片序列，而不需要 导航仪回声。方法：采用气动波纹管提供 呼吸位置信息，而不是导航仪回声。尽管 导航仪更准确，导航仪会留下信号损失带 穿过腹部，需要额外的处理时间。波纹管 信息很容易获得，而且采样率更高。在.期间 第一次通过序列、呼吸位置及其 对应的激励存储在各自的直方图中 切成薄片。在完成第一次传递后，来自所有 直方图用于确定受试者最常见的呼吸 位置(模式)。此后，每个单独切片的直方图 在重新获取期间关于该模式的范围被缩小。在.之前 每次重新获得激励，波纹管提供一种呼吸 位置。如果此位置将缩小切片的直方图，则 切片最糟糕的激发被重新获得。重新收购期 继续，直到所有直方图都足够窄或扫描 达到预定义的时间限制。结果：通过DVA和 呼吸触发有相似的目标，DVA保证 固定扫描时间内呼吸位置的最小方差。DVA 还允许与呼吸频率无关的一致的tr。 结论：FSE的DVA补偿减少了运动伪影，同时 有效利用扫描时间。它易于实现，可与 不合作的主题，并且不限制其他门控或对比度 参数。