PH Measurements of the Brain Using Phosphorus Magnetic Resonance Spectroscopy (31PMRS) in Healthy Men – Comparison of Two Analysis Methods

Abstract

SummaryBackgroundIntracellular pH provides information on homeostatic mechanisms in neurons and glial cells. The aim of this study was to define pH of the brain of male volunteers using phosphorus magnetic resonance spectroscopy (31PMRS) and to compare two methods of calculating this value.Material/MethodsIn this study, 35 healthy, young, male volunteers (mean age: 25 years) were examined by 31PMRS in 1.5 T MR system (Signa Excite, GE). The FID CSI (Free Induction Decay Chemical Shift Imaging) sequence was used with the following parameters: TR=4000 ms, FA=90°, NEX=2. Volume of interest (VOI) was selected depending on the size of the volunteers’ brain (11–14 cm3, mean 11.53 cm3). Raw data were analyzed using SAGE (GE) software.ResultsBased on the chemical shift of peaks in the 31PMRS spectrum, intracellular pH was calculated using two equations. In both methods the mean pH was slightly alkaline (7.07 and 7.08). Results were compared with a t-test. Significant difference (p<0.05) was found between these two methods.ConclusionsThe 31PMRS method enables non-invasive in vivo measurements of pH. The choice of the calculation method is crucial for computing this value. Comparing the results obtained by different teams can be done in a fully credible way only if the calculations were performed using the same formula.

Hydrogen Ion Dynamics of Cancer and a New Molecular, Biochemical and Metabolic Approach to the Etiopathogenesis and Treatment of Brain Malignancies

“…However, MG were not considered in these publications of our group, this being the first contribution in the literature dedicated to MG [12,13]. At the same time that these conceptual changes in oncology were taking place, the interest raised by the abnormalities of the intracellular and the extracellular pH (pHi and pHe) of both normal and brain cancer cells have shown a most beneficial “side effect” in the understanding the many levels of the pH-related paradigm, and/or the hydrogen ion (H + ) dynamics of cancer [3,13,14,15,16,17,18,19,20,21].…”

Brain aging: Evaluation of pH using phosphorus magnetic resonance spectroscopy

“…Additionally, differences between the pH values calculated in the present study and those reported by other research teams could result from the varied locations of the examined areas, because the pH values in various regions of the brain are different . The method of calculating pH is also significant . Therefore, in the Discussion, we do not quote any specific pH values reported by any researchers, and only make reference to age‐related pH changes observed by them.…”

“…If necessary, the phase was manually corrected (zero‐order phase correction, first‐order phase correction) and the entire spectrum was shifted along the x ‐axis so that the peak corresponding to the concentration of phosphocreatine (PCr) was at a value of 0 ppm. The pH value was calculated using the Henderson–Hasselbalch formula: where: δpi – difference between chemical shift of inorganic phosphate (P i ) and PCr.…”

“…Thanks to advancements in technology, it is possible to carry out non-invasive measurement of pH in any tissue of the human body using 31P MRS. 7,8 The aim of the present study was to identify the standard pH value in the entire brain volume using 31P MRS in healthy individuals of both sexes in different age groups, and then to determine whether there are differences in these values. Based on this information, it can be concluded whether brain pH changes with age and if this factor should be taken into account when assessing any pathological conditions.…”

Short‐term meditation training influences brain energy metabolism: A pilot study on 31P MR spectroscopy

“…Furthermore, brain pH can be measured using 31 P‐MRS by calculating the chemical shift difference between PCr and Pi (Cichocka et al., 2015; Petroff & Prichard, 1983). Normal brain activity can be associated with task‐related pH changes, as can environmental factors such as altitude (Shi et al., 2014).…”