31-Phosphorus Magnetic Resonance Spectroscopy in Evaluation of Glioma and Metastases in 3T MRI

Background: 31-Phosphorus magnetic resonance spectroscopy (31-P MRS) has excellent potential for clinical neurological practice because of its noninvasive in-vivo assessment of cellular energy metabolism and the indirect evaluation of the phospholipid composition of the cell membrane, intracellular pH, and intracellular Mg2+ concentration. Purpose: The aim of this study was to evaluate the metabolic characteristics of glioma and metastases using 31-P MRS and assess utility to differentiate both. Study Type: Prospective study. Population: Fifteen consecutive patients with brain tumor. Field Strength/Sequence: Three-tesla magnetic resonance imaging/three-dimensional MRS imaging sequence. Statistical Tests: Unpaired sample t-test, and one-way analysis of variance with Tukey's post-hoc test. Results: Significantly decreased values of phosphomonoesters/inorganic phosphate (PME/Pi) in the tumor group (1.22 ± 0.72) compared with controls (2.28 ± 1.44) with a p-value of 0.041 were observed. There is a significant decrease in phosphocreatine (PCr)/Pi values (energy demand) in the tumor group (2.76 ± 0.73) compared with controls (4.13 ± 1.75) with a p-value of 0.050. Significant increase in Pi/adenosine triphosphate (ATP) was noted in tumor group (0.28 ± 0.09) compared with controls (0.22 ± 0.08) with p-value 0.049. Among tumor group, PME/PCr values were significantly decreased in gliomas (0.35 ± 0.17) than metastasis (0.58 ± 0.23) compared with controls with a p-value of 0.047. A significant decrease in PME/ATP was noted in gliomas (0.25 ± 0.12) than metastasis (0.41 ± 0.14) compared with controls with a p-value of 0.034. The tumor group exhibits alkaline pH (7.12 ± 0.10) compared with the normal parenchyma (7.04 ± 0.06) with a significant p-value of 0.025. Glioma and metastasis could not be differentiated with pH. However, the perilesional edema of glioma shows alkaline pH (7.09 ± 0.06) and metastasis shows acidic pH (7.02 ± 0.05) with a significant p-value of 0.030. Conclusion: Our study provides new insight into the cellular constituents and pH of gliomas and metastases and results were significant in differentiation between these two. However, due to the additional high expense, it is available as a research tool in very few institutions in India.

Cardiovascular Health and Mitochondrial Function: Testing an Association

Background Although mitochondrial dysfunction appears to be a contributing factor in the pathogenesis of cardiovascular and metabolic diseases, empirical data on this association are still lacking. This study evaluated whether mitochondrial oxidative capacity, as assessed by phosphorus magnetic resonance spectroscopy, was associated with cardiovascular risk, as estimated by the Framingham Risk Score (FRS), and with a clinical history of cardiovascular disease (CVD), in community-dwelling adults. Method A total of 616 subjects from the Baltimore Longitudinal Study of Aging (mean age 66 years) underwent a comprehensive clinical evaluation. Mitochondrial oxidative capacity in skeletal muscle was assessed as post-exercise phosphocreatine recovery time constant by phosphorus magnetic resonance spectroscopy. Multivariate regression models were employed to determine the cross-sectional association of mitochondrial oxidative capacity with FRS and history of CVD. Results Decreased mitochondrial oxidative capacity was strongly associated with higher FRS independent of age, body composition, and physical activity. Lower oxidative capacity was also associated with a history of positive of CVD and higher number of CVD events. Conclusions We speculate that the observed association could reflect the effect of an excessive production of oxidative species by dysfunctional mitochondria. Furthermore, decreased energy production could hamper the functionality of heart and vessels. In turn, a malfunctioning cardiovascular apparatus could fail to deliver the oxygen necessary for optimal mitochondrial energy production, therefore creating a vicious cycle. Longitudinal studies are necessary to ascertain the directionality of the association and the eventual presence of common pathogenetic roots. In conclusion, mitochondria could represent an important target for intervention in cardiovascular health.

Intracellular Phosphate and ATP Depletion Measured by Magnetic Resonance Spectroscopy in Patients Receiving Maintenance Hemodialysis

BackgroundThe precise origin of phosphate that is removed during hemodialysis remains unclear; only a minority comes from the extracellular space. One possibility is that the remaining phosphate originates from the intracellular compartment, but there have been no available data from direct assessment of intracellular phosphate in patients undergoing hemodialysis.MethodsWe used phosphorus magnetic resonance spectroscopy to quantify intracellular inorganic phosphate (Pi), phosphocreatine (PCr), and βATP. In our pilot, single-center, prospective study, 11 patients with ESKD underwent phosphorus (31P) magnetic resonance spectroscopy examination during a 4-hour hemodialysis treatment. Spectra were acquired every 152 seconds during the hemodialysis session. The primary outcome was a change in the PCr-Pi ratio during the session.ResultsDuring the first hour of hemodialysis, mean phosphatemia decreased significantly (−41%; P<0.001); thereafter, it decreased more slowly until the end of the session. We found a significant increase in the PCr-Pi ratio (+23%; P=0.001) during dialysis, indicating a reduction in intracellular Pi concentration. The PCr-βATP ratio increased significantly (+31%; P=0.001) over a similar time period, indicating a reduction in βATP. The change of the PCr-βATP ratio was significantly correlated to the change of depurated Pi.ConclusionsPhosphorus magnetic resonance spectroscopy examination of patients with ESKD during hemodialysis treatment confirmed that depurated Pi originates from the intracellular compartment. This finding raises the possibility that excessive dialytic depuration of phosphate might adversely affect the intracellular availability of high-energy phosphates and ultimately, cellular metabolism. Further studies are needed to investigate the relationship between objective and subjective effects of hemodialysis and decreases of intracellular Pi and βATP content.Clinical Trial registry name and registration number Intracellular Phosphate Concentration Evolution During Hemodialysis by MR Spectroscopy (CIPHEMO), NCT03119818