Multimodality imaging

Combined optical/x-ray imaging

We have an ongoing collaboration with the radiation physics group where we are looking at potential advantages of combining optical and x-ray imaging. We have built a breast phantom with tissue-equivalent optical, x-ray and elastic properties [1], with a view to building a combined optical/x-ray imaging system [2].

We are also investigating the use of optical imaging and x-ray diffraction in radiotherapy as a marker of hypoxia.

Combined optical/EEG imaging

Optical imaging is sensitive to be haemodynamics of brain activation, whereas electroencephalography (EEG) is sensitive to the electrical activity. The interaction between these two mechanisms, known as neurovascular coupling, is actively researched. We are performing simultaneous EEG and optical imaging studies on infants and adults which allow neurovascular coupling to be examined directly in vivo. We have built a novel probe which enables simultaneous EEG and optical imaging to be performed in a manner which is easy to apply, allows for optimum coregistration of the two forms of data, and maximizes the number of sensors which can be applied to a given area. The probe consists of an array of "opto-electrodes", and has been evaluated using a dual modality, tissue-mimicking phantom and by performing a simple functional activation study of the human motor cortex [3]. We have also developed a phantom which can be used for simultaneous optical imaging and EEG measurements [4].

Combined optical/MRI imaging

A further example of multimodality imaging is provided by combining optical imaging with magnetic resonance imaging (MRI). MRI provides 3D images safely and with excellent spatial resolution, and optical imaging can provide unique functional information. We have built test  phantoms with tissue-equivalent optical and MR properties. Homogeneous phantoms were built with optical scatter and dye, with copper sulphate added to provide controllable MR contrast. We have also developed a method for building anisotropic phantoms using celery as an anisotropic scatterer.

Terahertz imaging

Terahertz (THz) imaging is an emerging medical imaging technique which provides spectroscopic data from 0.1 to 2 THz. We have worked with Teraview Ltd., to develop new analysis methods which draw from the well-developed approaches used in optical spectroscopy, to allow tissue composition to be measured quantitatively and reliably using THz techniques [5,6].

Photogrammetry

One of the chief advantages of combining optical imaging with other imaging methods is the acquisition of patient-specific anatomical information. However, using other methods brings disadvantages as well as advantages. X-rays are ionising and MRI is uncomfortable, noisy and expensive. We are investigating the use of stereophotography to provide patient-specific head surfaces unobtrusively both for optical tomography [7] and topography [8].

References

  1. Hebden J C, B D Price, A P Gibson, G Royle (2006). "A soft deformable tissue-equivalent phantom for diffuse optical tomography" Phys. Med. Biol. 51 p5581-5590. Full paper
  2. Price B, A P Gibson, J C Hebden, G Royle (2008). "Development Of Combined X-ray And Optical Mammography To Increase Specificity ". UK Radiological Congress Birminghan, UK 2-4 June 2008.
  3. Cooper RJ, Everdell NL, Enfield LC, Gibson AP, Worley A, Hebden, JC (2009) "Design and evaluation of a probe for simultaneous EEG and near-infrared
    imaging of cortical activation". Physics in Medicine and Biology, 54, 2093-2102. Full paper
  4. Cooper RJ, Bhatt D, Everdell NL, Hebden, JC (2009) "A tissue-like optical turbid and electrically conducting phantom for simultaneous EEG and near-infrared imaging". Physics in Medicine and Biology, 54, N403-N408.
  5. Reid C, A P Gibson, J C Hebden V P Wallace (2007). "An oil and water emulsion phantom for biomedical terahertz spectroscopy". 4th IEEE-EMBS International Summer School and Symposium on Medical Devices and Biosensors (ISSS-MDBS 2007) Cambridge UK, Aug 2007
  6. Reid C, A P Gibson, J C Hebden V P Wallace (2007). "The use of tissue mimicking phantoms in analysing contrast in THz pulsed imaging of biological tissue". The Joint 32nd International Conference on Infrared and Millimetre Waves and 15th International Conference on Terahertz Electronics, Cardiff UK, Sept 2007
  7. Abreu de Souza M, Robson, S, Hebden JC, Gibson AP, Sauret V (2006). "The photogrammetric determination of head surface shape and alignment for the optical tomography of newborn infants". International Society for Photogrammetry and Remote Sensing, Commission V, Dresden 25-27 September 2006
  8. Wong S, Robson S, Gibson, AP, Hebden, JC (2009) "Low cost real-time web-cam photogrammetry to determine the locations of optical topography sensors located on the human head". Remote Sensing and Photogrammetry Society Annual Conference 2009. Leicester, 8-11 September 2009