Journal of the Louisiana State Medical Society
DISCUSSION
The results of this study support our hypothesis and show that the average HU of cerebral contusions tends to decrease over time. When all scans are considered, it appears that the rate of decay of HU is higher initially, but that it levels off after a period of time (see Figure). The fact that there was a significant correlation between HU and time elapsed during the first 100 days but no correlation after the first 100 days supports this idea. However, there is a noticeable variation in the HU values from the initial scans of the patients, which is a potential confounding factor. This may be why the correlation becomes even stronger when the initial scans are omitted. There are two likely reasons for this variation: differences in the time period between the actual injury and the initial scan and variations in baseline brain density between individuals. 3 This study supports the idea that the relative age of cerebral contusions can be
Figure: When all scans are considered, there is a significant correlation between the average HU of the contusion area and the time elapsed. It appears that there is a lower rate of decrease in HU as the overall time interval increases.
REFERENCES 1. National Trauma Institute. Trauma statistics, updated April 2012. <http://www.nationaltraumainstitute.org/home/trauma_ statistics.html> (accessed 9/15/2013). 2. Centers for Disease Control and Prevention, Traumatic Brain Injury (TBI): Incidence and distribution, 2004. 3. Cala et al. Brain density and cerebrospinal fluid space size: CT for normal volunteers. American Journal of Neuroradiology . 1981 Jan-Feb;2(1):41-7.
differentiated, to a certain extent, using the HU values in the area of the contusions. This concept could be applicable in a number of settings, but it could be especially important in forensics and in medico-legal settings. For example, if a patient claims a contusion that is actually an old injury was caused by a recent accident, an abnormally low HU value in the area of the contusion could indicate that the recent accident did not cause the contusion. The current study is limited by a relatively small sample size, as well as the abovementioned variation in baseline brain density. Future studies could attempt to better con- trol for these factors. Taking into account the time between the injury itself and the initial scan could result in a more accurate assessment of the early changes in density of the contusions. A larger study that controls for these factors could also further elucidate the overall relationship between time and density of cerebral contusions.
Mrs. Moore II and Willett are Medical Students at Louisiana State University School of Medicine in Shreveport. Dr. Toledo is a Professor of Radiology, Neurology, and Anesthesiology and Director of Neuroradiology and Research at LSU School of Medicine in Shreveport. Dr. Youssef is Assistant Professor of Surgery at LSU School of Medicine in Shreveport.
120 J La State Med Soc VOL 166 May/June 2014
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