Imaging of non-accidental injury; what is clinical best practice?

Non-accidental injury (NAI) remains the leading cause of morbidity and mortality in children. Fractures are the second most common findings of NAI, after cutaneous lesions such as bruises and contusions. Imaging in NAI remains a controversial issue with little agreement concerning how, when and what imaging modalities should be used in the investigation of suspected cases. This review addresses the radiological investigations and findings of NAI, and the differential diagnoses of these findings. Adherence to the international guidelines for skeletal survey imaging is recommended. This ensures the content and quality of the radiographic series are of an optimal standard to improve the detection of occult fractures, and ensuring the accurate reporting of images. The involvement of a paediatric radiologist is important, if not essential in the diagnosis of NAI. In the evaluation of suspected cases, the role of the radiologist includes the detection of radiological findings suggestive of NAI, and the differentiation of these findings from normal variants and underlying pathologies. The diagnosis of NAI relies not only on radiological imaging, but also a combination of clinical and social findings. It is mandatory that all physicians work in close collaboration to improve diagnostic accuracy, as failure to diagnose NAI carries significant risk for morbidity.

Mechanical properties of the brain-skull interface.

Knowledge of the mechanical properties of the brain-skull interface is important for surgery simulation and injury biomechanics. These properties are known only to a limited extent. In this study we conducted in situ indentation of the sheep brain, and proposed to derive the macroscopic mechanical properties of the brain-skull interface from the results of these experiments. To the best of our knowledge, this is the first ever analysis of this kind. When conducting in situ indentation of the brain, the reaction force on the indentor was measured. After the indentation, a cylindrical sample of the brain tissue was extracted and subjected to uniaxial compression test. A model of the brain indentation experiment was built in the Finite Element (FE) solver ABAQUS™. In the model, the mechanical properties of the brain tissue were assigned as obtained from the uniaxial compression test and the brain-skull interface was modeled as linear springs. The interface stiffness (defined as sum of stiffnesses of the springs divided by the interface area) was varied to obtain good agreement between the calculated and experimentally measured indentor force-displacement relationship. Such agreement was found to occur for the brain-skull interface stiffness of 11.45 Nmm⁻¹/mm². This allowed identification of the overall mechanical properties of the brain-skull interface.