Accurate Quantification in Physiologic Phosphorus MR Spectroscopy

我们发现从灌注大鼠心脏的交替翻转角度获得的数据的变化被O-DAM校正消除了。相应的模拟表明，当代谢物变化不大时，可以进行精确的饱和度校正。使用典型参数，我们发现，正如预期的那样，在PCr中较小的分数变化可以实现更高程度的准确性。PCr的下降小于12%，使得PCr/Pi测量的准确度在20%以内。当TR = 2s时，PCr可降低50%以上，校正比例的准确度保持在20%以内。缺血再灌注实验的模拟表明，除了在浓度快速变化的情况下，获得的准确度很高。因此，即使在化学交换和T1变化的情况下，O-DAM程序也可以精确监测代谢物浓度。此外，由于能够更准确地量化应激停止后的PCr恢复，O-DAM方法可以更准确地测量代谢恢复的时间常数，这是一种广泛使用的线粒体合成能力标记。

We find that alternations in data acquired at alternating flip angles from the perfused rat heart are eliminated by the O-DAM correction. Corresponding simulations demonstrate that accurate saturation correction can be performed when metabolite changes are modest. Using typical parameters, we find that, as expected, greater degrees of accuracy can be achieved for smaller fractional changes in PCr. A decrease in PCr of less than 12% permits accuracy in PCr/Pi measurement to within 20%. For TR = 2 s, PCr can decrease by over 50% with accuracy of the corrected ratio remaining within 20%. Simulation of an ischemia-reperfusion experiment indicates the high degree of accuracy obtainable except at times of rapid concentration changes. Thus, the O-DAM procedure may permit accurate monitoring of metabolite concentrations even in the setting of chemical exchange and T1 changes. In addition, due to the ability to more accurately quantify PCr recovery after the cessation of stress, the O-DAM method permits a more accurate measurement of the time constant for metabolic recovery, a widely-used marker for mitochondrial synthetic capability.