Steinseifer Isabell K, Philips Bart W J, Gagoski Borjan, Weiland Elisabeth, Scheenen Tom W J, Heerschap Arend
Department of Radiology and Nuclear Medicine (667), Radboud University Medical Center, Nijmegen, The Netherlands.
Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Magn Reson Med. 2017 Mar;77(3):928-935. doi: 10.1002/mrm.26181. Epub 2016 Mar 10.
Cartesian k-space sampling in three-dimensional magnetic resonance spectroscopic imaging (MRSI) of the prostate limits the selection of voxel size and acquisition time. Therefore, large prostates are often scanned at reduced spatial resolutions to stay within clinically acceptable measurement times. Here we present a semilocalized adiabatic selective refocusing (sLASER) sequence with gradient-modulated offset-independent adiabatic (GOIA) refocusing pulses and spiral k-space acquisition (GOIA-sLASER-Spiral) for fast prostate MRSI with enhanced resolution and extended matrix sizes.
MR was performed at 3 tesla with an endorectal receive coil. GOIA-sLASER-Spiral at an echo time (TE) of 90 ms was compared to a point-resolved spectroscopy sequence (PRESS) with weighted, elliptical phase encoding at an TE of 145 ms using simulations and measurements of phantoms and patients (n = 9).
GOIA-sLASER-Spiral acquisition allows prostate MR spectra to be obtained in ∼5 min with a quality comparable to those acquired with a common Cartesian PRESS protocol in ∼9 min, or at an enhanced spatial resolution showing more precise tissue allocation of metabolites. Extended field of views (FOVs) and matrix sizes for large prostates are possible without compromising spatial resolution or measurement time.
The flexibility of spiral sampling enables prostate MRSI with a wide range of resolutions and FOVs without undesirable increases in acquisition times, as in Cartesian encoding. This approach is suitable for routine clinical exams of prostate metabolites. Magn Reson Med 77:928-935, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
在前列腺的三维磁共振波谱成像（MRSI）中，笛卡尔 k 空间采样限制了体素大小的选择和采集时间。因此，为了保持在临床可接受的测量时间内，大前列腺通常以降低的空间分辨率进行扫描。在此，我们提出一种半定位绝热选择性重聚焦（sLASER）序列，其具有梯度调制的与偏移无关的绝热（GOIA）重聚焦脉冲和螺旋 k 空间采集（GOIA-sLASER-Spiral），用于快速前列腺 MRSI，具有更高的分辨率和更大的矩阵尺寸。
使用直肠内接收线圈在 3 特斯拉进行磁共振成像。通过对体模和患者（n = 9）的模拟和测量，将回波时间（TE）为 90 毫秒的 GOIA-sLASER-Spiral 与回波时间为 145 毫秒的具有加权椭圆相位编码的点分辨波谱序列（PRESS）进行比较。
GOIA-sLASER-Spiral 采集能够在约 5 分钟内获得前列腺磁共振波谱，其质量与使用常见笛卡尔 PRESS 协议在约 9 分钟内获得的波谱相当，或者在更高的空间分辨率下，能更精确地显示代谢物的组织分布。对于大前列腺，可以实现扩展视野（FOV）和矩阵尺寸，而不会影响空间分辨率或测量时间。
螺旋采样的灵活性使得前列腺 MRSI 能够在不出现笛卡尔编码中采集时间不必要增加的情况下，实现广泛的分辨率和 FOV。这种方法适用于前列腺代谢物的常规临床检查。《磁共振医学》77:928 - 935, 2017。© 2016 国际磁共振医学学会。
