Detecting traumatic intracranial bleedings in a brain phantom using microwave technology

Traumatic Brain Injury (TBI) is one of the major causes of death due to injury and frequently occurs in road traffic accidents, assaults, sports injuries, etc. It has been estimated that TBI will become a leading cause of death in the near future. Intracranial bleedings is one of the most severe complications of TBI, and need to be detected and treated at an early phase to save the lives of these patients. The objective of this thesis was to make a realistic human brain phantom and assess the potential of Microwave Technology (MWT) for detecting intracranial bleedings due to head injury. MWT can detect bleedings based on the difference between the dielectric properties of blood and brain tissue. In this thesis we modeled a particularly common and dangerous type of intracranial bleeding, subdural hematoma, following descriptions of typical shape and clinically relevant size in the literature. Measurements were performed using a Microwave Helmet (MWH) developed by researchers at Chalmers University in collaboration with Medfield Diagnostics AB. Experiments were setup and conducted in the two labs at Chalmers and Medfield Diagnostics. Major series of experiments included measurements on bleeding and without bleeding phantoms in plastic buckets and in a human cranium. Initially different sizes of bleedings were tested in the plastic buckets, followed by creating bleeding phantoms of sizes 40, 70 and 110 mL inside the human cranium. The bleedings in the human cranium were made by cutting away a portion of the brain phantom with a scalpel and refilling with bleeding phantom. The measurements on the cranium were performed using the MWH consisting of 12 antennas, and the measurements on the plastic buckets were done using two antennas attached to the buckets’ sides. The measurement order was randomized when possible. Furthermore, potential interfering factors such as movements of the MWH/antennas and the cables, presence of a mobile phone on call close to the experimental setup, and presence of a person close to the setup, were also investigated. A classification algorithm was used to distinguish between phantoms without bleeding and phantoms with bleedings of different sizes. The classification results both for buckets and human cranium experiments showed that there was a clear difference between without bleeding and bleeding phantoms. The classification results for the human cranium phantom indicate that subdural hematoma of clinically relevant sizes can be detected using MWT. The tests on possibly interfering factors showed that human presence and mobile signals close to the experimental setup had clear effects. However, other factors did not show any clear interference. The results indicate that MWT has high potential for detecting intracranial hematomas, and may become a future complement to Computed Tomography (CT) for ambulatory use. The advantages like its low cost, small size and non ionizing radiation make this technology very attractive to use in an emergency setting. Acknowledgements I am very grateful to my supervisor Stefan Candefjord for providing me opportunity for doing this thesis. I really admire your efforts and support during the whole thesis. You have not only provided my great guidance and support but also gave me lot of confidence by constant encouragement throughout the thesis. I am more specifically very thankful to you for your help in making phantoms, performing experiments, writing report and presentation. Without your help it would be very hard to conduct this thesis. I am thankful to Stefan Kidborg and Patrick Dahlqvist at Medfield Diagnostics for providing me their time and resources for conducting experiments. The technical support and guidance from Stefan Kidborg was very useful in conducting successful experiments. I am also thankful to Professor Tomas McKelvey and Yinan Yu at Chalmers University for their help with classification algorithm and very useful discussions. I would also like to express my gratitude to my examiner Andreas Fhager and his colleagues Xuezhi Zeng, Hana Trefna and Johanna Gellermann at Chalmers University for their support and guidance. I am also thankful to all staff at MedTech West for providing me a working place and resources for work. Malik Ahzaz Ahmad Gothenburg, June 2012