1st supervisor: Tomoki Arichi, King’s College London
2nd supervisor: Jo Hajnal, King’s College London
Additional supervisor: Bernhard Kainz, Imperial College London
Aim of the PhD Project:
- Develop a fully integrated immersive Virtual Reality (VR) experience in the MRI scanner.
- Integrate multi-modal sensory and physiological information into the VR experience to establish a new level of VR immersion and interaction that is completely congruent with subject experience.
- Explore related brain activity using “real-world” fMRI experiments.
Project Description / Background:
The MRI scanner environment is noisy and claustrophobic, making it challenging to effectively image vulnerable populations such as children or those with cognitive difficulties. Whilst sedation or anesthesia can be used to improve patient cooperation, they have physiological effects which can potentially impact both long-term health and brain activity. An alternative is to attempt desensitisation and habituation of subjects in a preparation phase prior to MRI examination, and Virtual Reality (VR) has been recently used for this purpose. However, this approach does not remove the harsh realities of the MR examination process itself and the subject remains acutely aware of their surroundings and stresses associated with these remain. With these factors in mind, we have recently developed a non-intrusive MR compatible VR system which can provide users with an immersive interactive simulated environment whilst lying inside the confines of the MRI scanner. Subjects are immersed in the visual environment via an MR compatible projector placed inside the scanner bore projecting directly into the VR headset.
A key factor that dictates the effectiveness of VR methods in other clinical applications (such as treating anxiety or phobia disorders, or to replace anaesthesia) is how immersed the subject feels in the artificial environment. In this context, the ability to interact effectively and thus increase the sense of “presence” is vital to not only improve attention but also to positively influence complex concepts such as emotional responses and learning. This sense of presence is disturbed when a subject receives incongruent sensory signals from the real world such as additional noise, touch, or those related to normal physiology. In the MRI setting, taking these factors into account is even more important for effective immersion, as there are numerous other alien sensations (such as gradient noise, table vibrations etc) to consider.
These factors are of further importance for Functional MRI (fMRI), which has become the tool of choice in neuroscientific and clinical applications for studying patterns of brain activity. However, constraints imposed by the MR environment and hardware limitations mean that what can be learnt is often the result of a crude juxtaposition of stimulus presentation, response monitoring and imaging data. fMRI studies therefore generalise poorly to the real world as they represent highly atypical physiological conditions and are feasible only for populations who can meet certain criteria.
In this project, the student will therefore work with our newly developed MR compatible VR system. This system incorporates a pair of MRI compatible cameras mounted inside the VR headset to provide real-time information about visual behavior and head position (and enable interaction through gaze estimation), noise cancelling headphones, physiological monitoring (heart rate, oxygen saturations, temperature) and an external microphone and camera to allow interaction through voice and gestures. The student will aim to use novel engineering, software, and computer vision solutions to fuse the complex VR stimuli and the aforementioned multimodal information, which together will provide an entirely novel means of VR interaction and a rich source of information with which to deepen the sense of immersion.
Figure 1: The MR compatible Virtual Reality system which will be used in the project in use. It consists of a MR compatible projector which is placed on the examination table which enters the scanner bore and a VR headset mounted on the receive head coil. There is a pair of infrared cameras integrated into the headset which can precisely track subject eye and head movements. The subject wears active noise cancelling headphones and can also talk into a microphone attached to the headcoil.