Chan Rachel W, Von Deuster Constantin, Stoeck Christian T, Harmer Jack, Punwani Shonit, Ramachandran Navin, Kozerke Sebastian, Atkinson David
Centre for Medical Imaging, University College London, London, UK.
NMR Biomed. 2014 Nov;27(11):1300-12. doi: 10.1002/nbm.3190. Epub 2014 Sep 15.
Fractional anisotropy (FA) obtained by diffusion tensor imaging (DTI) can be used to image the kidneys without any contrast media. FA of the medulla has been shown to correlate with kidney function. It is expected that higher spatial resolution would improve the depiction of small structures within the kidney. However, the achievement of high spatial resolution in renal DTI remains challenging as a result of respiratory motion and susceptibility to diffusion imaging artefacts. In this study, a targeted field of view (TFOV) method was used to obtain high-resolution FA maps and colour-coded diffusion tensor orientations, together with measures of the medullary and cortical FA, in 12 healthy subjects. Subjects were scanned with two implementations (dual and single kidney) of a TFOV DTI method. DTI scans were performed during free breathing with a navigator-triggered sequence. Results showed high consistency in the greyscale FA, colour-coded FA and diffusion tensors across subjects and between dual- and single-kidney scans, which have in-plane voxel sizes of 2 × 2 mm(2) and 1.2 × 1.2 mm(2) , respectively. The ability to acquire multiple contiguous slices allowed the medulla and cortical FA to be quantified over the entire kidney volume. The mean medulla and cortical FA values were 0.38 ± 0.017 and 0.21 ± 0.019, respectively, for the dual-kidney scan, and 0.35 ± 0.032 and 0.20 ± 0.014, respectively, for the single-kidney scan. The mean FA between the medulla and cortex was significantly different (p < 0.001) for both dual- and single-kidney implementations. High-spatial-resolution DTI shows promise for improving the characterization and non-invasive assessment of kidney function.
通过扩散张量成像（DTI）获得的分数各向异性（FA）可用于在不使用任何造影剂的情况下对肾脏进行成像。髓质的FA已被证明与肾功能相关。预计更高的空间分辨率将改善肾脏内小结构的描绘。然而，由于呼吸运动和对扩散成像伪影的敏感性，在肾脏DTI中实现高空间分辨率仍然具有挑战性。在本研究中，使用靶向视野（TFOV）方法在12名健康受试者中获得高分辨率FA图和彩色编码的扩散张量方向，以及髓质和皮质FA的测量值。受试者采用TFOV DTI方法的两种实施方案（双肾和单肾）进行扫描。DTI扫描在自由呼吸期间使用导航器触发序列进行。结果显示，在受试者之间以及双肾和单肾扫描之间，灰度FA、彩色编码FA和扩散张量具有高度一致性，其平面内体素大小分别为2×2 mm²和1.2×1.2 mm²。获取多个连续切片的能力使得能够在整个肾脏体积上对髓质和皮质FA进行量化。双肾扫描的髓质和皮质FA平均值分别为0.38±0.017和0.21±0.019，单肾扫描的平均值分别为0.35±0.032和0.20±0.014。双肾和单肾实施方案中，髓质和皮质之间的平均FA均存在显著差异（p<0.001）。高空间分辨率DTI有望改善对肾功能的表征和非侵入性评估。
