An Improved Imaging Analysis For Quantitatively Measuring Brain Slice Volume

The most important and direct changes of brain injuries including brain ischemia are the changes in brain morphological structures. For evaluating the brain morphological changes, there are various methods. In addition to the microscopic methods for observing cellular alterations, many methods are used to evaluate the relatively macroscopic alterations, including: (1) magnetic resonance imaging (MRI) used in animals in vivo or patients clinically;(2) computer-assisted image analysis;(3) other methods, such as computerized tomography (CT), light transmittance and so on. This study was aimed to improve the computer-assisted image analysis.The techniques of computer-assisted imaging analysis are widely used in the studies of brain ischemia and other brain injuries. They are mainly used in two fields: imaging analysis for the image samples and video tracking analysis for moving objects (animals). Recently, a computer-assisted analysis software system combined 2 techniques was developed in our laboratory, named AnalyPower1.0 including a sub-system MedBrain1₀. MedBrain1₀ was used for analysis of brain slices or sections, such as calculating the area or volume of brain infarcts, the ratio of left/right hemispheres (for evaluating brain edema). However, in order to become more precise this sub-system and measurement should be improved because of some shortages.To improve the software and measurement, this study evaluated the precise of MedBrain1₀ and brain slice assessment in comparison with typical methods for measuring areas and volumes of brain slices from rats and mice. The software system was improved, named MedBrain2₀, and used to analyze the volumes of brain slices from brain focal ischemic mice for its usefulness.In the experiments, the improved imaging analysis showed a good linear correlation to precisely measured areas of pieces of paper (r = 1.000). In comparison with relatively precise methods, weighing method and special gravity method, the relation between imaging analysis and precise methods was confirmed. The thickness of the brain slices was adjusted by the measurement of brain longitudinal length (longitudinal length -K>), then the volumes was calculated. By the improved method and MedBrain2₀, the measured volumes was well correlated to the volumes measured by the precise method (special gravity), in rats r = 0.809 (? = 45, P < 0.001) and in mice r = 0.844 (? = 74, P < 0.001). The volume data measured by the improved imaging analysis was more precise than those before improvement. Also, to confirm the usefulness of this method, the volumes of the brain slices of mice with brain focal ischemia were tested. We found that the ischemic hemispheres were significantly larger than non-ischemic hemispheres at 6 and 24 h after brain focal ischemia, indicating the usefulness in evaluation of brain injury.From these results, we concluded as following:1. Improved system MedBrain2₀ can precisely measure area (r = 1.000).2. MedBrain2₀ and calculation by adjusted thickness remarkably improves the precise of measurement for the volumes of brain slices both of rats and mice (r > 0.8). And the usefulness is well confirmed in the volume measurement of left and right hemispheres of focal brain ischemic mice.3. Imaging analysis is a simple and quantitative method for measurement of injured brain volume, and the improved method will used in pharmacological and other studies more effectively.