Dynamics of metabolic changes in intracranial metastases and distant normal-appearing brain tissue after stereotactic radiosurgery: a serial proton magnetic resonance spectroscopy study.

The present study evaluated the dynamics of metabolic changes in intracranial metastases and distant normal-appearing brain after stereotactic radiosurgery (SRS). Forty neoplasms were evaluated with single-voxel proton magnetic resonance spectroscopy ((1)H-MRS) both before and after treatment. From one to six examinations (median, 3) were done in each individual case during follow-up. At the time of each investigation additional (1)H-MRS was obtained from the normal-appearing brain distant from the radiosurgical target. Investigated metabolites included N-acetylaspartate (NAA), choline-containing compounds (Cho), creatine (Cr), and mobile lipids (Lip). Within the first month after SRS responded tumors showed a statistically significant increase in NAA/Cho ratio, and decrease of Cho content and Lip-to-normal brain Cr (nCr) ratio. By contrast, statistically significant metabolic alterations were not detected in stabilized tumors. Statistically significant volumetric and metabolic changes were not marked between three and 12 months after treatment in non-progressing lesions. Alternatively, decrease of NAA/Cho ratio, NAA content and Cr content, and increase in Lip/nCr ratio and Cho content were evident in progressive neoplasms, and subtle metabolic alterations could be revealed even before the increase in the lesion volume. Metabolic characteristics of normal-appearing brain distant from the radiosurgical target did not show statistically significant changes within the first year after treatment. In conclusion, additional use of serial (1)H-MRS during follow-up after SRS for intracranial metastases permits detailed evaluation of the metabolic tumor response and may be potentially helpful for early prediction of recurrence.

Differentiation of High-Grade and Low-Grade Gliomas Using Pattern Analysis of Long-Echo Single-Voxel Proton Magnetic Resonance Spectroscopy ((1)H-MRS).

The usefulness of proton magnetic resonance spectroscopy ((1)H-MRS) for glioma grading is not clear, particularly due to the absence of standard criteria for data analysis. Previously we had developed an original classification of the pathological (1)H-MRS spectra based on the identification of the predominant metabolite peak, N-acetylaspartate (NAA) for Type I, choline-containing compounds (Cho) for Type II, and mobile lipids (Lip) for Type III, and presence or absence of other metabolite peaks: lactate (Lac), Lip, or Cho. The present study evaluated the effectiveness of this classification in grading of previously non-treated gliomas. A total of 38 low-grade and 33 high-grade neoplasms were investigated. Four tumors had (1)H-MRS spectra Type I, and all of those were low-grade. Three tumors had (1)H-MRS spectra Type III, and all those were glioblastomas. Fifteen tumors with (1)H-MRS spectra Type II had a Lip/NAA ratio more than 1 (Type II C with moderate elevation of lipids), and 12 of those neoplasms were high-grade. The differences in distribution of high-grade and low-grade gliomas among another 49 gliomas with (1)H-MRS spectra Type II did not depend on the presence of Lac and/or Lip peaks, and in this subgroup NAA/Cho ratio was also evaluated. Inclusion of both characteristics (type of the (1)H-MRS spectrum and NAA/Cho ratio with defined cut-off level of 0.6) into the diagnostic algorithm yielded 72% diagnostic accuracy (95% confidence interval: 62%-82%) in discriminating high-grade and low-grade neoplasms. In conclusion, pattern analysis of the pathological (1)H-MRS spectra using the proposed classification along with evaluation of NAA/Cho ratio might be helpful for non-invasive glioma grading.

[The collateral venous blood flow and the surgical procedure in parasagittal meningiomas]. / Kollateral'nyi venoznyi krovotok i khirurgicheskaia taktika pri parasagittal'nykh meningiomakh.

Peculiarities of the collateral venous bloodflow were analysed in 242 cases of parasagittal meningiomas (PM). The cerebral veins participated in collateral bloodflow in 52.1% of cases with tumours of the anterior third of the superior sagittal sinus (SSS), whereas in 39% of such cases the retrograde flow through proximal SSS have been found. Neoplasms of the middle/posterior third of SSS led to the collateral venous bloodflow through the anastomoses of the cerebral veins in 67% of cases. In 56% of patients the collateral flow was through extracerebral veins. The absence of strict conformities in the development of the collateral venous bloodflow leads to necessity of its intraoperative control by EEG monitoring. Severe changes of bioelectrical activity (14.9% of cases) are an indication for division of the surgical procedure into several stages.

[Results of the surgical treatment of patients with basal extracerebral parastem tumors of large and giant dimensions]. / Rezul'taty khirurgicheskogo lecheniia bol'nykh s bazal'nymi vnemozgovymi parastvolovymi opukholiami bol'shikh i gigantskikh razmerov.

A retrospective analysis of the results of treatment of 123 patients with large and giant basal extracerebral parastem tumors was made. The majority of the neoplasms (81%) were acoustic neuromas and meningiomas. The nearest results of the treatment were good in 103 patients and unfavorable results were noted in 20 patients. Postoperative mortality was 8.9%. Four factors negatively influencing the outcome were revealed during the statistical analysis (p < 0.05): low Karnofsky score at admission, regrowth (recurrence) of the tumor, previously performed radiation therapy and shunt surgery as the first stage of treatment. These prognostic factors must be taken into account when choosing the best treatment of patients with parastem tumors.

[The characteristics of the surgical treatment of basal meningiomas with supra-subtentorial spread]. / Osobennosti khirurgicheskogo lecheniia bazal'nykh meningiom s supra-subtentorial'nym rasprostraneniem.

The results of surgical treatment of 63 patients with basal meningiomas with supra-subtentorial spread were analyzed. The study has shown the effectiveness of one-stage tumor removal via supra-transtentorial approach with skull base bones resection. It is recommended to estimate an extent of operation on the basis of intraoperative assessment of biological behavior of the tumor, including interrelationship of tumor capsule and brainstem pia mater. Mortality rate was decreased from 23.8% to 11.1% following introduction of these principles.