Using imaging to time head trauma in infants

Knowing what to look for on cranial computed tomography (CT) scans and magnetic resonance imaging (MRI) can help identify and time abusive head trauma (AHT) in infants, thus facilitating identification and exclusion of potential perpetrators.

Researchers at Pennsylvania State College led a new study, the largest to date on the subject, that describes and discusses the appearances of various abusive traumatic injuries on both types of scans at different time points. The research extends the work of a small pilot study done previously by one of the current study’s authors. The hope is that the work will provide a reference for physicians called to testify with regard to AHT in infants.

In this new study, investigators looked at 148 infants aged younger than 24 months who were admitted to a medical center with AHT and a documented time of injury over a 10-year period.

The researchers determined that:

• Parenchymal hypodensities on CT scans usually materialize within hours of the injury.

• Mixed-density subdural hematomas (SDHs) are common after AHT.

• Hypodense areas commonly appear within an acute SDH within days of an injury, which is earlier than previously thought.

• The time required for the disappearance of hyperdense blood within a mixed area can only broadly be defined and requires further study.

• A small amount of rebleeding into an SDH is relatively common and is almost always asymptomatic.

• Pinpointing the age of blood within an SDH using MRI sequences is difficult.

• MRI scans, particularly diffusion and apparent diffusion coefficient (ADC) sequences, may better identify parenchymal abnormalities.

The researchers conclude that although limitations exist, injury timing can usually be broadly established with radiologic findings.

According to a report by the Centers for Disease Control and Prevention, estimates of the incidence of AHT vary, but most range from 20 to 30 cases per 100,000 children aged younger than 1 year. 

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