Rosenkrantz Andrew B, Zhang Bei, Ben-Eliezer Noam, Le Nobin Julien, Melamed Jonathan, Deng Fang-Ming, Taneja Samir S, Wiggins Graham C
Department of Radiology, NYU Langone Medical Center, New York, New York, USA.
J Magn Reson Imaging. 2015 Jan;41(1):226-32. doi: 10.1002/jmri.24511. Epub 2013 Nov 20.
To report design of a simplified external transmit-receive coil array for 7 Tesla (T) prostate MRI, including demonstration of the array for tumor localization using T2-weighted imaging (T2WI) at 7T before prostatectomy.
Following simulations of transmitter designs not requiring parallel transmission or radiofrequency-shimming, a coil array was constructed using loop elements, with anterior and posterior rows comprising one transmit-receive element and three receive-only elements. This coil structure was optimized using a whole-body phantom. In vivo sequence optimization was performed to optimize achieved flip angle (FA) and signal to noise ratio (SNR) in prostate. The system was evaluated in a healthy volunteer at 3T and 7T. The 7T T2WI was performed in two prostate cancer patients before prostatectomy, and localization of dominant tumors was subjectively compared with histopathological findings. Image quality was compared between 3T and 7T in these patients.
Simulations of the B1(+) field in prostate using two-loop design showed good magnitude (B1(+) of 0.245 A/m/w(1/2)) and uniformity (nonuniformity [SD/mean] of 10.4%). In the volunteer, 90° FA was achieved in prostate using 225 v 1 ms hard-pulse (indicating good efficiency), FA maps confirmed good uniformity (14.1% nonuniformity), and SNR maps showed SNR gain of 2.1 at 7T versus 3T. In patients, 7T T2WI showed excellent visual correspondence with prostatectomy findings. 7T images demonstrated higher estimated SNR (eSNR) in benign peripheral zone (PZ) and tumor compared with 3T, but lower eSNR in fat and slight decreases in tumor-to-PZ contrast and PZ-homogeneity.
We have demonstrated feasibility of a simplified external coil array for high-resolution T2-weighted prostate MRI at 7T.
报告一种用于7特斯拉（T）前列腺MRI的简化外部发射-接收线圈阵列的设计，包括在前列腺切除术前使用7T的T2加权成像（T2WI）对该阵列进行肿瘤定位的演示。
在模拟不需要并行传输或射频匀场的发射机设计之后，使用环形元件构建了一个线圈阵列，前后两排各包含一个发射-接收元件和三个仅用于接收的元件。使用全身模型对该线圈结构进行了优化。进行了体内序列优化，以优化前列腺中实现的翻转角（FA）和信噪比（SNR）。在一名健康志愿者身上于3T和7T对该系统进行了评估。在两名前列腺癌患者前列腺切除术前进行了7T T2WI，并将主要肿瘤的定位与组织病理学结果进行了主观比较。比较了这些患者在3T和7T时的图像质量。
使用双环设计对前列腺中的B1(+)场进行模拟显示，其幅度良好（B1(+)为0.245 A/m/w(1/2)）且均匀性良好（不均匀性[标准差/均值]为10.4%）。在志愿者中，使用225 v 1 ms硬脉冲在前列腺中实现了90°FA（表明效率良好），FA图证实均匀性良好（不均匀性为14.1%），SNR图显示7T时的SNR增益相对于3T为2.1。在患者中，7T T2WI与前列腺切除术后的结果显示出极佳的视觉对应性。7T图像显示，与3T相比，良性外周区（PZ）和肿瘤中的估计SNR（eSNR）更高，但脂肪中的eSNR更低，肿瘤与PZ的对比度和PZ的均匀性略有下降。
我们已经证明了一种简化的外部线圈阵列用于7T高分辨率T2加权前列腺MRI的可行性。
