个别优化的动态并行传输脉冲用于7T的3D高分辨率空间成像
Gian Franco Piredda1, Emilie Sleight2,3, Thomas Yu1,4,5
1Swiss Innovation Hub, Siemens Healthineers International AG, Lausanne, Switzerland.
Magnetic resonance in medicine
|May 24, 2025
概括
动态并行传输 (pTx) 脉冲通过实现均的翻转角度分布来改善7T MRI SPACE成像. 这导致更好的图像质量,并使先进的MRI序列在更高场强度的临床应用成为可能.
科学领域:
- 磁共振成像 (MRI) 是一种磁共振成像技术.
- 生物医学工程 生物医学工程
- 物理 物理学 物理
背景情况:
- 临床7TMRI提供优越的信号噪声比 (SNR) 和光谱分辨率,与较低的场强度相比.
- 在7TMRI中,实现空间均的翻转角度分布是一个重大挑战,特别是在采样完美与应用优化对比度使用不同的翻转角度演变 (SPACE) 序列的情况下.
- SPACE 序列使用长列重定焦脉冲,具有不同的翻转角度,加剧了翻转角度不均性问题.
研究的目的:
- 调查可扩展的动态并行传输 (pTx) 脉冲的有效性,以实现7T的均3D高分辨率SPACE脑成像.
- 为了应对在7T SPACE序列中空间均翻转角度分布的挑战.
- 为了使7T应用广泛使用的临床对比度,并提高图像质量.
主要方法:
- 非参数化和可扩展的动态pTx脉冲是使用快速在线定制 (FOCUS) 设计的,用于SPACE序列中的激发,重新聚焦和反转.
- 优化涉及使用B0和多通道B1+地图以在特定吸收率 (SAR) 约束下实现翻转角度均性.
- 用获得的B0和B1+地图来定制特定对象的pTx脉冲,并强制执行一个对称条件以实现可扩展性. 在7T时获得的T1,T2,FLAIR和DIR SPACE图像在5名健康受试者中获得,以与传统的循环偏振 (CP) 脉冲进行比较.
主要成果:
- 使用FOCUS pTx脉冲获得的图像显示,与传统的CP脉冲相比,在所有对比度中,SNR和同质性得到了改善.
- 定量分析显示,图像强度的变化系数 (COV) 显著降低,特别是在小脑.
- FLAIR图像显示了显著的46%的COV减少,这表明图像同质性得到了显著改善.
结论:
- 个别优化的动态pTx脉冲用于7T的3D高分辨率SPACE成像,成功实现了临床上可接受的图像均性.
- 开发的FOCUS脉冲可以在7T时应用广泛使用的临床对比物,如FLAIR和DIR.
- 这一进步克服了7TMRI的一个关键局限性,为其更广泛的临床采用铺平了道路.
相关概念视频
Computed Tomography
6.4K
Tomography refers to imaging by sections. Computed tomography (CT) is a non-invasive imaging technique that uses computers to analyze several cross-sectional X-rays to reveal minute details about structures in the body.
The technique was invented in the 1970s and is based on the principle that as X-rays pass through the body, they are absorbed or reflected at different levels. In the technique, a patient lies on a motorized platform while a computerized axial tomography (CAT) scanner rotates...
The technique was invented in the 1970s and is based on the principle that as X-rays pass through the body, they are absorbed or reflected at different levels. In the technique, a patient lies on a motorized platform while a computerized axial tomography (CAT) scanner rotates...
6.4K
NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences
936
A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a radio frequency pulse along the x-axis, the nuclei absorb energy corresponding to their Larmor frequencies and achieve resonance. This shifts the net magnetization vector from the z-axis toward the transverse plane. This angle of rotation of the magnetization vector, or the flip angle, is proportional to the duration and intensity of the pulse.
936
Positron Emission Tomography
5.9K
Positron emission tomography (PET) is a medical imaging technique involving radiopharmaceuticals — substances that emit short-lived radiation. Although the first PET scanner was introduced in 1961, it took 15 more years before radiopharmaceuticals were combined with the technique and revolutionized its potential.
One of the main requirements of a PET scan is a positron-emitting radioisotope, which is produced in a cyclotron and then attached to a substance used by the part of the body...
One of the main requirements of a PET scan is a positron-emitting radioisotope, which is produced in a cyclotron and then attached to a substance used by the part of the body...
5.9K
X-ray Imaging
7.8K
German physicist Wilhelm Röntgen (1845–1923) was experimenting with electrical current when he discovered that a mysterious and invisible "ray" would pass through his flesh but leave an outline of his bones on a screen coated with a metal compound. In 1895, Röntgen made the first durable record of the internal parts of a living human: an "X-ray" image (as it came to be called) of his wife’s hand. Scientists worldwide quickly began their own experiments with...
7.8K


