Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.
Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
Magn Reson Med. 2018 Jan;79(1):286-297. doi: 10.1002/mrm.26675. Epub 2017 Apr 11.
To dramatically accelerate compartmental-average longitudinal (T ) and transverse (T ) relaxation measurements using the minimal-acquisition linear algebraic modeling (SLAM) method, and to validate it in phantoms and humans.
Relaxation times were imaged at 3 Tesla in phantoms, in the abdomens of six volunteers, and in six brain tumor patients using standard inversion recovery and multi-spin-echo sequences. k-space was fully sampled to provide reference T and T measurements, and SLAM was performed using a limited set of phase encodes from central k-space. Anatomical compartments were segmented on scout images post-acquisition, and SLAM reconstruction was implemented using two algorithms. Compartment-average T and T measurements were determined retroactively from fully sampled data sets, and proactively from SLAM data sets at acceleration factors of up to 16. Values were compared with reference measurements. The compartment's localization properties were analyzed using the discrete spatial response function.
At 16-fold acceleration, compartment-average SLAM T measurements agreed with the full k-space compartment-average results to within 0.0% ± 0.7%, 1.4% ± 3.4%, and 0.5% ± 2.9% for phantom, abdominal, and brain T measurements, respectively. The corresponding T measurements agreed within 0.2% ± 1.9%, 0.9% ± 7.9%, and 0.4% ± 5.8%, respectively.
SLAM can dramatically accelerate relaxation time measurements when compartmental or lesion-average values can suffice, or when standard relaxometry is precluded by scan-time limitations. Magn Reson Med 79:286-297, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
使用最小采集线性代数建模（SLAM）方法显著加速分室平均纵向（T ）和横向（T ）弛豫测量，并在体模和人体中验证其效果。
在体模、6 名志愿者腹部和 6 名脑肿瘤患者中，使用标准反转恢复和多自旋回波序列，在 3T 磁共振上进行弛豫时间成像。使用完全采样的 k 空间提供参考 T 和 T 测量值，并且使用中心 k 空间的有限相编码来执行 SLAM。在采集后对解剖分区进行 scout 图像分割，并使用两种算法来执行 SLAM 重建。从完全采样数据集追溯性地和从 SLAM 数据集前瞻性地确定分室平均 T 和 T 测量值，加速因子最高可达 16。将这些值与参考测量值进行比较。使用离散空间响应函数分析分区的定位特性。
在 16 倍加速时，分室平均 SLAM T 测量值与全 k 空间分室平均结果的一致性在 0.0%±0.7%、1.4%±3.4%和 0.5%±2.9%之间，分别为体模、腹部和脑 T 测量值。相应的 T 测量值的一致性分别在 0.2%±1.9%、0.9%±7.9%和 0.4%±5.8%之间。
当分室或病变平均值即可满足要求，或者扫描时间限制排除了标准弛豫测量时，SLAM 可以显著加速弛豫时间测量。磁共振医学 79：286-297，2018。© 2017 国际磁共振学会。
