Application of 31P MR spectroscopy to the brain tumors.

OBJECTIVE: To evaluate the clinical feasibility and obtain useful parameters of (31)P magnetic resonance spectroscopy (MRS) study for making the differential diagnosis of brain tumors. MATERIALS AND METHODS: Twenty-eight patients with brain tumorous lesions (22 cases of brain tumor and 6 cases of abscess) and 11 normal volunteers were included. The patients were classified into the astrocytoma group, lymphoma group, metastasis group and the abscess group. We obtained the intracellular pH and the metabolite ratios of phosphomonoesters/phosophodiesters (PME/PDE), PME/inorganic phosphate (Pi), PDE/Pi, PME/adenosine triphosphate (ATP), PDE/ATP, PME/phosphocreatine (PCr), PDE/PCr, PCr/ATP, PCr/Pi, and ATP/Pi, and evaluated the statistical significances. RESULTS: The brain tumors had a tendency of alkalization (pH = 7.28 ± 0.27, p = 0.090), especially the pH of the lymphoma was significantly increased (pH = 7.45 ± 0.32, p = 0.013). The brain tumor group showed increased PME/PDE ratio compared with that in the normal control group (p = 0.012). The ratios of PME/PDE, PDE/Pi, PME/PCr and PDE/PCr showed statistically significant differences between each brain lesion groups (p < 0.05). The astrocytoma showed an increased PME/PDE and PME/PCr ratio. The ratios of PDE/Pi, PME/PCr, and PDE/PCr in lymphoma group were lower than those in the control group and astrocytoma group. The metastasis group showed an increased PME/PDE ratio, compared with that in the normal control group. CONCLUSION: We have obtained the clinically applicable (31)P MRS, and the pH, PME/PDE, PDE/Pi, PME/PCr, and PDE/PCr ratios are helpful for differentiating among the different types of brain tumors.

Discrimination of brain abscess and cystic tumor by in vivo proton magnetic resonance spectroscopy.

Proton magnetic resonance (MR) spectroscopy was evaluated for the differentiation of brain abscesses and cystic brain tumors. Proton MR spectroscopy was performed in vivo in two patients with brain abscess and eight patients with various cystic brain tumors (anaplastic astrocytoma, glioblastoma, and metastatic brain tumor). MR imaging with contrast medium demonstrated ring-like enhanced mass lesions in all patients. The various resonance peaks in proton MR spectra were assigned to metabolites according to chemical shifts. Treatment of the cystic brain lesions was based on the information from proton MR spectroscopy. Aspirated pus from one patient with brain abscess was examined using ex vivo proton MR spectroscopy. The in vivo spectra of brain abscess contained resonance peaks attributed to acetate, lactate, alanine, amino acids, and lipids in both cases, and an additional peak of succinate in one case. In vivo spectra of the neoplasms contained resonance peaks corresponding to lactate, lipids, choline, creatine, and N-acetyl aspartate. Proton MR spectroscopy is useful for discriminating brain abscess from cystic tumors with similar neuroimaging appearance, which is very important for determining the treatment strategy.

[Morphofunctional features of the hypothalamo-hypophyseal system in experimental cerebral abscess]. / Morfofunktsional'nye osobennosti gipotalamo-gipofizarnoi neirosekretornoi sistemy pri éksperimental'nom abstsesse golovnogo mozga.

The morphological characteristics of the hypothalamo-pituitary neurosecretory system (HPNS) were studied in 123 rats with an experimental abscess in the temporal area of the brain. It was found that changes in the HPNS in this pathology ran 2 stages corresponding to the periods of the development of the pyoinflammatory process in the cerebral tissue. In the first period (at the 3rd-10th day of the development of a cerebral abscess) the functional activity of the HPNS was inhibited: a decrease in both synthesis and excretion of neurohormones was evident. The mortality rate at this period was the highest (21 of 23 rats). At the second period (the 15th-30th day of experiment) there was an increase in the activity of neurosecretory nuclei and a decrease in the mortality rate (2 rats). It is suggested that the absence of NPNS activation was one of the causes of the high mortality rate at the first period of the experiment which was related to the direct damaging action of the abscess localized in the cerebral portions having the direct impact on the neurosecretory system.