Abusive head injuries to infants two years old and under are a very serious threat to public health in the United States. The mortality rate in infants based on abusive head traumas alone are 15 to 25 percent per year. Often, because infants cannot identify perpetrators, clinicians must provide information regarding the time of the injury, along with whether or not they think the injury is a sign of abuse.

New ways to employ magnetic resonance imagining (MRI) and computerized tomography (CT) techniques may make it easier for doctors to identify injuries as abusive or not, and also identify a time frame in which the injury occurred.

MRI scans give detailed images of any part of the body. Images made by an MRI are high-resolution and give very minute details about changes to structures, like the brain, and can even record the way it functions in real time. However, they can be costly and take some time to develop. On the other hand, CT scans are a lower resolution but can be faster and less expensive than MRI scans of the brain. CT scans are ideal for identifying major issues in the brain like tumors, the existence of blood, or skull fractures.

In a study of 115 infants with a head injury, researchers looked for intracranial abnormalities, indicative of an abusive injury, in the infants' brains using a combination of CT and MRI scans. The use of both scans reveals much more information than each individual scan alone. For 105 of these infants, researchers were able to identify the date of injury. They did this by identifying abnormalities in brain tissue.

Researchers were able to identify abnormalities like skull fractures, hypodensities, hemorrhage, and atrophying, or the death, of brain tissue. Twenty-six percent of the infants had skull fractures, but this type of injury is lasting and so its variability cannot be used to date an injury. However, hypodensities and hemorrhages change with time and can reveal how long ago they formed as a result of injury.

In the study, researchers found that 38 percent of the infants had hypodensities in their brains and 92 percent had a hemorrhage. A hypodensity of the brain is an area that has become less dense thanks to damage or a lack of blood supply. A hemorrhage in the brain is when the vessels of the brain have broken and blood is present amid brain tissue, instead of in blood vessels. This is problematic, as blood can kill brain cells. Both of these occurrences are symptomatic of abusive head trauma, especially in infants who must be treated with care, as their bodies are still very fragile and prone to injury.

The researchers found, using a series of five CT scans, that some injuries can be identified for longer periods of time than others. This technique can establish a timeline for injuries. For example, hypodensities can be identified for up to 80 hours after trauma, while an acute hemorrhage can only be identified for up to five hours after trauma. Similarly, atrophying of brain cells can be identified by CT scans up to 15 days after injury.

The use of serial MRI scan proved to be even more useful alongside the CT scans. MRI scans on 49 of the infants indicated that a hypodensity appears within one day of injury and can last a minimum of five days or a maximum of 180 days.

This information from serial MRI and CT scans is crucial in setting up a timeline for which a child may have suffered an abusive head injury. Not only does this technique help identify perpetrators but it can also be crucial for maintaining a child's health, as head injuries, at any age, can be fatal if left untreated and can provide a predisposition for strokes, heart attacks, aneurysms, and dementia.

Source: Bradford R, Choudhary AK, Dias MS. Serial neuroimaging in infants and abusive head trauma: timing abusive injuries. Journal of Neurosurgery: Pediatrics. 2013.