Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee 37232-2310, USA.
Magn Reson Med. 2012 May;67(5):1427-33. doi: 10.1002/mrm.23130. Epub 2011 Sep 27.
Measurements of relaxation rates in the rotating frame with spin-locking techniques are sensitive to substances with exchanging protons with appropriate chemical shifts. The authors develop a novel approach to exchange-rate selective imaging based on measured T(1ρ) dispersion with applied locking field strength, and demonstrate the method on samples containing the X-ray contrast agent Iohexol with and without cross-linked bovine serum albumin. T(1ρ) dispersion of water in the phantoms was measured with a Varian 9.4-T magnet by an on-resonance spin-locking pulse with fast spin-echo readout, and the results used to estimate exchange rates. The Iohexol phantom alone gave a fitted exchange rate of ~1 kHz, bovine serum albumin alone was ~11 kHz, and in combination gave rates in between. By using these estimated rates, we demonstrate how a novel spin-locking imaging method may be used to enhance contrast due to the presence of a contrast agent whose protons have specific exchange rates.
采用自旋锁定技术测量在旋转框架中的弛豫率对具有适当化学位移的质子交换物质敏感。作者基于应用锁定场强度测量的 T(1ρ) 色散开发了一种新的交换率选择成像方法，并在含有 X 射线造影剂碘海醇的样品上进行了演示，这些样品中含有或不含有交联牛血清白蛋白。通过在共振自旋锁定脉冲与快速自旋回波读出，使用 9.4-T 磁体在水模体中测量 T(1ρ) 色散，并用结果估计交换率。单独的碘海醇模体拟合的交换率约为 1 kHz，单独的牛血清白蛋白为 11 kHz，两者的组合则在两者之间。通过使用这些估计的速率，我们展示了一种新的自旋锁定成像方法如何可用于增强造影剂的对比度，因为造影剂的质子具有特定的交换速率。
