X-ray elastography: a novel approach to breast imaging

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The mechanical properties of tissue, such as stiffness, have long been known to be an important indicator of the health of tissue. Indeed, manual palpation is used regularly by clinicians as part of routine diagnostic procedures. A range of techniques have been developed in order to obtain images, both in two and three dimensions, of tissue stiffness. This approach, known as elastography, is significantly more powerful than manual palpation as the clinician is able to visualise the location, and relative stiffness, of tissue within the body.Existing elastography techniques are based on ultrasonoghraphic imaging (i.e. ultrasound, US), magnetic resonance imaging (MRI) and optical imaging. US based elastography has developed to the point where it is able to be used as part of a routine breast cancer diagnosis protocols. One of the problems with these established techniques is that their ability to resolve small features, such as small tumours, degrades as these tumours are located within the body. For example, optical techniques are able to resolve features as small as 0.02mm, however, only if they are located within about 1mm of the skin. Tumours over 0.1mm in size can be detected using US elastography if they are located less than 10cm from the skin surface, and so on.We propose to make use of a recently developed X-ray imaging technique, known as phase imaging, which provides images of biological tissue which are much clearer than conventional X-ray imaging. Using this technique we believe it will be possible to obtain images of tissue stiffness, resolving features as small as 0.02mm, located deep within the body, thus breaking the limitation of existing elastography techniques. Although applicable to a range of applications, we will apply this technique to breast cancer imaging. If successful, the technique could be applied in screening, diagnosis and treatment of breast cancer. In particular, it could be integrated into a form of three-dimensional mammography known as tomosynthesis, giving the radiologist an additional form of contrast upon which to make their diagnosis. Once a suspicious lesion has been detected at the screening stage, this technique could be used in follow up imaging, again to provide the radiologist with an additional form of contrast upon which to make their diagnosis. Finally, if surgery is required, it may be possible to use this technique to check that the tumour has been completely removed at the time of surgery, rather than requiring a patient to return for follow-up surgery to remove any remaining tumour.