Proceedings Article | 16 March 2020
KEYWORDS: Acoustics, Tissues, Ultrasonography, Tissue optics, Head, Skull, Magnetic resonance imaging, Tomography, Photoacoustic spectroscopy, Brain
In cases of child abuse, the leading cause of death is head trauma. Due to the developing skull and brain, the vast majority of victims are less than one year old. An estimated 4 cases of abusive head trauma (AHT) occurs for every 10,000 babies born each year, with a 25% mortality rate. In standard cases, infants undergo X-ray (CT) or magnetic resonance (MRI) imaging when AHT is suspected. Repeated imaging of these patients is desired, since the symptoms associated with abusive head trauma change over time. By measuring the rate of change the precise time and likely cause of the trauma can be more easily identified. CT and MRI are not attractive options for the desired repeated imaging, due to the radiation, high cost, and unavailability at the bedside. Diagnosis of head trauma using imaging is based on several factors, including the presence of skull fractures, subdural hematoma, and hydrocephalus. Thermoacoustic combined tomography (TACT), which synergistically integrates ultrasound tomography (UT), photoacoustic tomography (PAT), and radio frequency acoustic tomography (RAT) is uniquely suited for imaging these symptoms at point-of-care. To verify this hypothesis, in silico experiments were performed on clinical MRI data of infants using our custom developed TACT simulation platform. Speed of sound measurements made using ultrasound are able to identify fractures in the skull, while photoacoustics is sensitive to the molecular contrast of blood, and is able to image subdural hematomas. Radio frequency acoustic tomography is most sensitive to cerebrospinal fluid, necessary for imaging hydrocephalus. Since this technology may be utilized for repeated imaging at the bedside, these multimodal TACT images can provide crucial information for the timing, and therefore cause of infant head trauma, as well as monitor the effect of treatment.
