Estimating Elapsed Time of Brain Hemorrhage Using Computed Tomography Value-based Parameters

We measured the time-dependent change of computed tomography (CT) values for a blood sample in a syringe during 20 days expecting that the (average, maximum) CT values may be used to estimate the elapsed time after hemorrhage. The average CT value (CTave) rapidly increased for the first 50 min. The maximum CT value (CTmax) increased step by step to take the largest value (82.4 HU) one day later, and subsequently the CTmax decreased slowly to become 72.0 HU 20 days later. We conclude that the rapid increase of the CTave at the beginning is due to the fibrin generation, the increase of the CTmax is a result of the formation of the fibrin net, and the subsequent decrease of CTmax is caused by fibrinolysis. Tentative experimental formula for the time-dependent CTmax change at each increasing stage and decreasing stage are given to estimate the elapsed time after hemorrhage.