In-vivo measurement of brain relaxation after lobectomies

Very little data exists on the visco-elastic properties of the living human brain tissue and collection of such data is vital for mechanical modelling. The purpose of this study was to measure the rate of relaxation of brain that has been compressed by tumour after surgical decompression. Seven patients who underwent a lobectomy for an intracranial space occupying lesion were included in the study. All underwent two CT scans within the first 24 h after the surgery. Volumes of the residual void on the serial CT scan were calculated using tools in the image acquisition software. There was a rapid expansion of the brain to fill up the void space in the first 24 h after surgery. The average rate of relaxation of the compressed brain is 2.25(0.76 - 6.64) ml/h. The graphs plotted for the volume of the void space against the time after surgery when the CT scans were done can be used to further explore the dynamics of brain relaxation. The rate of brain relaxation in the first 24 h after removal of a mass lesion averages 2.25(0.76 - 6.64) ml/h in this study. Further studies using more frequent data collection would allow for more accurate definition of the rate of relaxation.