Alkaline pH in intracranial tuberculomas: A (31)Phosphorus magnetic resonance spectroscopy study

OBJECTIVES: Intracranial tuberculomas are one of the common causes of space-occupying lesions of the brain in developing countries. Proton ((1)H) magnetic resonance spectroscopy (MRS) has shown lipid peak in intracranial tuberculomas as a characteristic feature. Phosphorus ((31)P) MRS has been used to evaluate intracranial lesions and to calculate tissue pH non-invasively. The aim of this study is to evaluate intracranial tuberculomas using (31)PMRS. MATERIALS AND METHODS: Intracranial tuberculomas proven by stereotactic or surgical biopsy were included in the study. After routine T1- and T2-weighted sequences, (31)P MRS was performed using single-voxel intravoxel in vivo spectroscopy (ISIS) technique in the central core of the tuberculoma (voxel size 1–2 mm(3)). The pH was estimated using Petroff ’s method using the chemical shift between phosphocreatine and Pi. RESULTS: (31)P MRS was available for 26 patients, in which there was significant positive correlation between high-energy phosphate metabolites, (markers of bioenergetic status), and low-energy phosphate metabolites (membrane phospholipids and inorganic phosphate). The calculated pH was slightly alkaline and varied from 6.97 to 7.22. CONCLUSION: Intracranial tuberculomas showed alkaline pH in (31)P MRS and this may be useful in the characterization of these lesions and possibly also in their treatment.