Application of VRML for three-dimensional interactive real-time comparison of OCT structures with standard histology

Optical coherence tomography (OCT) is a potentially useful 'optical biopsy' tool in medicine. To realize this potential doctors must be able to interpret OCT images with at least the same accuracy as conventional histology. It is therefore important that some accurate method of comparing OCT images with conventional histology be found. Despite numerous OCT vs. conventional histology studies in the literature the methods used for comparison have, by necessity, been approximate because it is not possible to cut a physical tissue section in the same plane as the OCT optical section (partly due to histology processing artefacts). In this paper we present a method of rendering solid tissue volumes with semi-transparency using the Virtual Reality Modelling Language (VRML) and devise a VRML script which allows any two volume data sets to be manipulated within the same region of virtual space. This allows the structure of a whole volume of tissue imaged with OCT to be directly compared with the serial section reconstruction of the conventionally stained histology. As the whole volume is visualized any corresponding tissue regions can be more easily identified despite tissue processing artefacts. We demonstrate the effectiveness of our method usng an ex vivo biopsy of human breast carcinoma.