Thermonavigation in the Surgery of Parasagittal Meningiomas Using Semiconductor Vision Infrared Thermograph (SVIT)

Objective: To assess the effectiveness of thermonavigation with the help of a semiconductor vision infrared thermograph (SVIT) to project the parasagittal meningioma on the scalp for planning the surgical approach.

Introduction: It is known that the additional heat in cases of meningovascular brain tumors, which is generated by its own tumor vasculature, increases local blood flow and increases metabolism. This is accompanied by a local increase of temperature and an increase in light luminescence in the area of projection of tumor on the skin surface. The temperature difference in 1.0-1.5° C is a parameter that we used as a diagnostic criterion for thermonavigation in case of meningiomas. SVIT is capable of detecting the absolute temperature of small areas of the examined surface with a high degree of accuracy. The received data are displayed on a computer monitor in a color palette with accurate indication of temperature parameters at any point of the study area.

Materials and Methods: From 2006 to 2008, as an additional study in 20 patients with parasagittal meningiomas, a thermal imaging survey was conducted using a highly sensitive thermal imaging camera, SVIT. This involved recording the temperature from the skin surface of the patient's head in the area of the proposed location of the tumor. The detected sites with a significantly higher temperature compared with other related parts of a scalp were reflected on a computer monitor.

Results: The maximum difference of the temperature between tumor projection site and other areas of the scalp was 4.6°C (32.6°C in the area of meningioma and 28°C around the tumor); the minimum difference was 1.1°C (range of temperatures was from 31.1°C to 30.0°C). The average temperature difference in our study was 1.96 ± 0.15°C. Registered spots with significantly higher value of temperature corresponded to localization of parasagittal meningioma. Using this data, the skin incision and craniotomy were planned. The entire stage takes approximately 2 to 3 minutes.

Conclusions: Neuronavigation using thermovision corresponded to localization of the tumor on MRI and CT scans in all 20 cases. Therefore this method can be used as an option in planning surgical approach.