Combined acquisition technique (CAT) for high-field neuroimaging with reduced RF power
Combined acquisition technique (CAT) for high-field neuroimaging with reduced RF power
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DOI：
10.1007/s10334-012-0362-3
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发表时间：
2013-08-01
影响因子：
2.3
通讯作者：
Jakob, Peter M.
中科院分区：
文献类型：
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作者：
Choli, Morwan;Blaimer, Martin;Jakob, Peter M.
临床上的3T磁共振成像系统正在迅速增加，并且已经安装了静电场为7T甚至更高的MRI系统。射频功率沉积与静磁场强度的平方成正比，并用比吸收率(SAR)来表征。因此，存在明确的安全限度，以避免患者发热。在这里，我们描述了一种混合方法，与快速自旋回波(TSE)序列相比，显著降低了SAR。我们调查了联合采集技术(CAT)在3T和7T高场神经成像中的潜在好处。TSE/EPI CAT实验在志愿者和患者身上进行，并与标准TSE和GRASE方案进行比较。讨论了T2加权CAT成像存在的问题和解决方法，给出了在3和7 T上获得的T2和质子密度对比度的活体图像，与标准TSE相比，SAR显著降低(最高可达60%)。图像质量与TSE相当，但CAT显示的伪影比GRASE序列少。CAT是一种很有前途的高场神经成像候选者，最高可达7T。通过降低SAR，可以缩短两次激励之间的等待时间或成像更多切片，从而减少总体测量时间。
Clinical 3 T MRI systems are rapidly increasing and MRI systems with a static field of 7 T or even more have been installed. The RF power deposition is proportional to the square of the static magnetic field strength and is characterized by the specific absorption rate (SAR). Therefore, there exist defined safety limits to avoid heating of the patient. Here, we describe a hybrid method to significantly reduce the SAR compared to a turbo-spin-echo (TSE) sequence.We investigate the potential benefits of a combined acquisition technique (CAT) for high-field neuroimaging at 3 and 7 T. The TSE/EPI CAT experiments were performed on volunteers and patients and compared with standard TSE and GRASE protocols. Problems and solutions regarding T2 weighted CAT imaging are discussed.We present in vivo images with T2 and proton density contrast obtained on 3 and 7 T with significant SAR reduction (up to 60 %) compared with standard TSE. Image quality is comparable to TSE but CAT shows fewer artifacts than a GRASE sequence.CAT is a promising candidate for neuroimaging at high fields up to 7 T. The SAR reduction allows one to shorten the waiting time between two excitations or to image more slices thereby reducing the overall measurement time.