Computer Assisted Measurement of Colorectal Polyps

Adenomas are polyps of the colorectum that have the potential to develop into colon cancer. However, some adenomas never become malignant tumors, or if so, progression from adenoma into cancer takes a long time. As a result, screening colonoscopy programs were established in order to detect and resect adenomas at an early stage. After resection, polyps should be sent to pathology in order to make a histological diagnosis. Approximately 40-50% of all polyps have adenomatous histology whereas others contain benign histology (e.g. hyperplastic or inflammatory polyps). The latter polyps do not bear the risk to develop colon cancer.

The bigger a polyp is the greater the chance is of it being malignant. During colonoscopy polyp size can be estimated visually by comparing the polyp with an opened biopsy forceps. The span of an opened forceps is 7 mm. Prior to using this technique, the forceps has to be inserted into the colon through a small working channel of the endoscope. Information on the actual adenoma size is crucial as surveillance recommendations depend on the size of the resected polyps. Moreover current guidelines contain the possibilities to disregard hyperplastic polyps in the sigmoid colon if the polyp size is below 5 mm. This means that diminutive hyperplastic polyps (< 5mm) do not necessarily require resection due to their benign dignity. However, there is increasing evidence that large human bias effects exist in estimating the size of polypoid lesions. For example, it has been shown that endoscopists exhibit terminal digit preferences leading to an exaggeration of estimated polyp size. In consequence the human bias problem might lead to wrong adenoma surveillance decisions.

There is no doubt that technical devices are needed which can support endoscopists in finding the right declaration of polyp sizes. The aim of the current project is to create a computer program that is able to automatically measure polyp sizes during colonoscopy.