Golman Klaes, Ardenkjaer-Larsen Jan H, Petersson J Stefan, Mansson Sven, Leunbach Ib
Amersham Health Research and Development AB, Medeon, SE-205 12 Malmö, Sweden.
Proc Natl Acad Sci U S A. 2003 Sep 2;100(18):10435-9. doi: 10.1073/pnas.1733836100. Epub 2003 Aug 20.
Dynamic nuclear polarization has enabled hyperpolarization of nuclei such as 13C and 15N in endogenous substances. The resulting high nuclear polarization makes it possible to perform subsecond 13C MRI. By using the dynamic nuclear polarization hyperpolarization technique, 10% polarization was obtained in an aqueous solution of 100 mM 13C-labeled urea, ready for injection. The in vivo T1 relaxation time of 13C in the urea solution was determined to 20 +/- 2 s. Due to the long relaxation time, it is possible to use the hyperpolarized substance for medical imaging. A series of high-resolution ( approximately 1-mm) magnetic resonance images were acquired, each with a scan time of 240 ms, 0-5 s after an i.v. injection of the hyperpolarized aqueous [13C]urea solution in a rat. The results show that it is possible to perform 13C angiography with a signal-to-noise ratio of approximately 275 in approximately 0.25 s. Perfusion studies with endogenous substances may allow higher spatial and/or temporal resolution than is possible with current proton imaging techniques.
动态核极化技术已能够使内源性物质中的诸如碳-13（13C）和氮-15（15N）等原子核实现超极化。由此产生的高核极化使得在亚秒级时间内进行碳-13磁共振成像（13C MRI）成为可能。通过使用动态核极化超极化技术，在100 mM碳-13标记尿素的水溶液中获得了10%的极化，可用于注射。测定尿素溶液中碳-13的体内T1弛豫时间为20±2秒。由于弛豫时间长，有可能将超极化物质用于医学成像。在大鼠静脉注射超极化的[13C]尿素水溶液后0至5秒内，采集了一系列高分辨率（约1毫米）的磁共振图像，每次扫描时间为240毫秒。结果表明，有可能在约0.25秒内以约275的信噪比进行碳-13血管造影。与内源性物质的灌注研究相比，可能比当前的质子成像技术具有更高的空间和/或时间分辨率。
