pH from Pi-PCr

[Andrzej Liebert]

Hello

I have been using the jMRUI 5.0 to analyse some 31P MRS spectra. Last day I found however a little mistake in your implementation of the pH measurement from Pi-PCr peaks. The mistake is in the formula for the pH calculation: In your case the formula is pH=Pa+log10((3.27-delta0)/(delta0-delta2)).

The right formula should be pH=Pa+log10((delta0-delta1)/(delta2-delta0)).

I realized this by accident and than checked also if the calculation is also fitting to the formula given by your interface and it does fit. The difference between your formula and the right one is maybe not big (max observed by me was around 0.08pH) but I think it still should be corrected.

As a reference I can send you to the following articles with which I doulbe checked the formula:

Moon, Richard B., and John H. Richards. “Determination of intracellular pH by 31P magnetic resonance.” Journal of Biological Chemistry 248.20 (1973): 7276-7278.

Quistorff, Bjørn. “Some quantitative aspects of 31 P magnetic resonance spectroscopy in vivo in an exercise physiology context.” 2nd WSEAS International Conference on Biomedical Electronics and Biomedical Informatics, Moskwa. 2009.

Regards
Andrzej Liebert

[Author]

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