Transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) is gaining significant acceptance as a noninvasive treatment for motion disorders and shows promise for novel applications such as blood-brain barrier opening for tumor treatment. A typical procedure relies on CT-derived acoustic property maps to simulate the transfer of ultrasound through the skull. Accurate estimates of the acoustic attenuation in the skull are essential to accurate simulations, but there is no consensus about how attenuation should be estimated from CT images and there is interest in exploring MR as a predictor of attenuation in the skull. In this study, we measure the acoustic attenuation at 0.5, 1, and 2.25 MHz in 89 samples taken from two ex vivo human skulls. CT scans acquired with a variety of X-ray energies, reconstruction kernels, and reconstruction algorithms, and MR images acquired with ultrashort and zero echo time sequences are used to estimate the average Hounsfield unit value, MR magnitude, and T2 ^* value in each sample. The measurements are used to develop a model of attenuation as a function of frequency and each individual imaging parameter.

中文翻译：

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声学衰减：多频测量及其与CT和MR成像的关系

经颅磁共振引导聚焦超声（tcMRgFUS）作为运动障碍的非侵入性治疗方法已获得广泛认可，并显示出其新颖的应用前景，例如用于治疗肿瘤的血脑屏障。典型的程序依赖于CT衍生的声学特性图来模拟超声波通过颅骨的传输。准确估计头骨中的声音衰减对于进行精确的模拟至关重要，但是关于如何从CT图像估计衰减的问题尚无共识，因此有兴趣探索MR作为预测头骨中衰减的因素。在这项研究中，我们测量了从两个采样点采集的89个样本在0.5、1和2.25 MHz处的声衰减离体人类的头颅骨。通过各种X射线能量，重建内核和重建算法获取的CT扫描，以及通过超短和零回波时间序列获取的MR图像，可用于估计每个样本中的平均Hounsfield单位值，MR幅值和T2 ^*值。这些测量用于建立衰减模型，该模型是频率和每个单独的成像参数的函数。