Lagemaat Miriam W, Philips Bart W J, Vos Eline K, van Uden Mark J, Fütterer Jurgen J, Jenniskens Sjoerd F, Scheenen Tom W J, Maas Marnix C
From the *Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands; and †Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany.
Invest Radiol. 2017 May;52(5):295-301. doi: 10.1097/RLI.0000000000000342.
The aim of this study was to evaluate the technical feasibility of prostate multiparametric magnetic resonance imaging (mpMRI) at a magnetic field strength of 7 T.
In this prospective institutional review board-approved study, 14 patients with biopsy-proven prostate cancer (mean age, 65.2 years; median prostate-specific antigen [PSA], 6.2 ng/mL), all providing signed informed consent, underwent 7 T mpMRI with an external 8-channel body-array transmit coil and an endorectal receive coil between September 2013 and October 2014. Image and spectral quality of high-resolution T2-weighted (T2W) imaging (0.3 × 0.3 × 2 mm), diffusion-weighted imaging (DWI; 1.4 × 1.4 × 2 mm or 1.75 × 1.75 × 2 mm), and (H) MR spectroscopic imaging (MRSI; real voxel size, 0.6 mm in 7:16 minutes) were rated on a 5-point scale by 2 radiologists and a spectroscopist.
Prostate mpMRI including at least 2 of 3 MR techniques was obtained at 7 T in 13 patients in 65 ± 12 minutes. Overall T2W and DWI image quality at 7 T was scored as fair (38% and 17%, respectively) to good or very good (55% and 83%, respectively). The main artifacts for T2W imaging were motion and areas of low signal-to-noise ratio, the latter possibly caused by radiofrequency field inhomogeneities. For DWI, the primary artifact was ghosting of the rectal wall in the readout direction. Magnetic resonance spectroscopic imaging quality was rated fair or good in 56% of the acquisitions and was mainly limited by lipid contamination.
Multiparametric MRI of the prostate at 7 T is feasible at unprecedented spatial resolutions for T2W imaging and DWI and within clinically acceptable acquisition times for high-resolution MRSI, using the combination of an external 8-channel body-array transmit coil and an endorectal receive coil. The higher spatial resolutions can yield improved delineation of prostate anatomy, but the robustness of the techniques needs to be improved before clinical adoption of 7 T mpMRI.
本研究旨在评估在7T磁场强度下进行前列腺多参数磁共振成像（mpMRI）的技术可行性。
在这项经机构审查委员会批准的前瞻性研究中，14例经活检证实为前列腺癌的患者（平均年龄65.2岁；前列腺特异性抗原[PSA]中位数为6.2 ng/mL）均签署了知情同意书，于2013年9月至2014年10月期间使用外部8通道体部阵列发射线圈和直肠内接收线圈进行了7T mpMRI检查。由2名放射科医生和1名光谱学家对高分辨率T2加权（T2W）成像（0.3×0.3×2 mm）、扩散加权成像（DWI；1.4×1.4×2 mm或1.75×1.75×2 mm）以及（氢）磁共振波谱成像（MRSI；实际体素大小，0.6 mm，采集时间7分16秒）的图像和光谱质量进行5分制评分。
13例患者在65±12分钟内于7T下获得了包括3种磁共振技术中至少2种的前列腺mpMRI。7T时T2W和DWI的总体图像质量评分中等（分别为38%和17%）至良好或非常好（分别为55%和83%）。T2W成像的主要伪影是运动和低信噪比区域，后者可能由射频场不均匀性引起。对于DWI，主要伪影是读出方向上直肠壁的鬼影。磁共振波谱成像质量在56%的采集过程中被评为中等或良好，主要受脂质污染限制。
使用外部8通道体部阵列发射线圈和直肠内接收线圈的组合，在7T下进行前列腺多参数磁共振成像对于T2W成像和DWI而言，以前所未有的空间分辨率是可行的，对于高分辨率MRSI而言在临床可接受的采集时间内也是可行的。更高的空间分辨率可以更好地描绘前列腺解剖结构，但在临床采用7T mpMRI之前，这些技术的稳健性需要进一步提高。
