Terahertz Pulsed Imaging of lower gastrointestinal mucosa : an in vitro study

• Main Author: Reese, George Edward
• Other Authors: Tekkis, Paris; Goldin, Robert
• Published: Imperial College London 2015
• Subjects: 610
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.668229

Medical imaging using Terahertz frequency radiation is in its infancy. Optical adjuncts to enhance the diagnostic precision of white light endoscopy are not new and almost all wavelengths of the electromagnetic spectrum have, at some point, been investigated to this end. The ultimate aim of an endoscopic technique is to identify 100% of mucosal lesions and to classify them with 100% specificity. Methods: This thesis examined the sensitivity and specificity of current technology to accurately identify colonic pathology using a diagnostic precision analysis of published data. The effect of biomaterials such as blood, mucus and faeces on Terahertz radiation was assessed using human tissue samples from health volunteers. The ability to discriminate pathological from normal colonic mucosa was assessed using terahertz radiation to interrogate excised samples of human colon. The physical nature of variation between pathological and normal colonic mucosa was assessed using histological markers in an attempt to identify the cause of terahertz radiation contrast. Results: Current technology has a sensitivity of 95% and a specificity of 78% in a non- inflamed colon. Terahertz pulsed imaging is a sensitive and specific technique for in vitro classification of colonic mucosal pathology. TPI may be a useful adjunct in the presence of inflamed mucosal tissue. Although there were too few data from the present study to quantify any potential benefit. The effects of blood, stool and mucus on TPI are similar but less pronounced than water. Immunohistochemical analysis has demonstrated an association between vascular and lymphatic density with neoplasia. This may be a mechanism for TPI discrimination of colonic pathology. TPI could in the future contribute to a minimally invasive method of in vivo diagnosis of colonic dysplasia or malignancy. Larger scale and in vivo trials of the technology are necessary to further investigate the potential clinical benefit.