Rosen Yael, Lenkinski Robert E
Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA.
Acad Radiol. 2009 Jul;16(7):886-9. doi: 10.1016/j.acra.2009.01.010. Epub 2009 Apr 17.
Sodium magnetic resonance imaging (MRI) of the kidneys has been used to spatially map areas of sodium-concentrating activity and to quantify the corticomedullary sodium gradient in various physiologic and pathophysiologic conditions. In this case study, sodium MRI of a clinically well-functioning transplanted kidney was performed to determine whether its sodium gradient could be detected and quantified using this method.
Sodium MRI was performed on a 3T scanner with a commercial rectangular sodium surface coil placed on the lower abdomen over the palpable transplanted kidney. A three-dimensional gradient echo sequence, modified for multinuclear imaging, was applied to acquire (23)Na images.
Five main renal pyramids within the medulla were detected, and the corticomedullary sodium gradient was quantified in each renal pyramid by both region of interest-based and pixel-by-pixel analyses, resulting in a mean medulla/cortex signal-to-noise ratio of 1.8 +/- 0.1 (n = 5) and a mean linear increase slope of 1.1 +/- 0.1 relative arbitrary units per mm (n = 5).
The feasibility and usability of (23)Na MRI of a human renal allograft was demonstrated. Further studies are required to determine the clinical significance of this technique in the follow-up of patients after renal transplantation.
肾脏的钠磁共振成像（MRI）已被用于在空间上绘制钠浓缩活动区域，并在各种生理和病理生理条件下量化皮质髓质钠梯度。在本病例研究中，对临床功能良好的移植肾进行钠MRI检查，以确定是否可以使用该方法检测和量化其钠梯度。
在一台3T扫描仪上进行钠MRI检查，将一个商用矩形钠表面线圈置于下腹部可触及的移植肾上方。应用一个针对多核成像进行修改的三维梯度回波序列来采集（23）Na图像。
在髓质内检测到五个主要肾锥体，并通过基于感兴趣区域和逐像素分析对每个肾锥体的皮质髓质钠梯度进行了量化，结果显示髓质/皮质平均信噪比为1.8±0.1（n = 5），平均线性增加斜率为每毫米1.1±0.1相对任意单位（n = 5）。
证明了人类同种异体移植肾（23）Na MRI的可行性和实用性。需要进一步研究以确定该技术在肾移植患者随访中的临床意义。
