Targeting Colon Cancer through Enhanced Virtual Colonoscopies. When screening for colon cancer, hundreds of cross-sectional images (left figure) of the patient’s abdomen are obtained during a single CT colonoscopy scan. In order to greatly reduce the amount of time required for the radiologist to review these data, Creare has developed methods for automatically generating a 3D virtual reconstruction of the patient's colon, with enhanced coloring (right figure) to highlight suspicious polyp-shaped regions.

Creare engineers are working to make it easier and safer to screen for colon cancer. Current screening methods for the disease are invasive, uncomfortable, and inconvenient. We are creating new data analysis algorithms and three-dimensional visualization techniques to make CT colonography (CTC), or “virtual colonoscopy,” the new gold standard test for cancer screening.

In 2004 more than 146,000 people were diagnosed with colon cancer and more than 55,000 people died from the disease. Treatment costs reached over $6.5 billion, second only to breast cancer. Yet if it’s caught early enough, colorectal cancer can be treated very successfully. The five-year survival rate of patients with localized cancer is 90% – but that number drops to less than 10% for those whose cancer has already spread at the time of detection.

Based on these facts, physicians and public health officials encourage all Americans between the ages of 50 to 70 to undergo regular colorectal cancer screening. Currently, less than half of this target group have been screened. The most common current screening technique, optical colonoscopy, requires rigorous bowel cleansing prior to the exam and sedation to alleviate pain associated with insertion of the colonoscope, a long, flexible viewing device, into the colon. As a result, many patients avoid the procedure due to the fear of pain and/or the inconvenience of the bowel cleansing and the inability to drive after sedation. Further, optical colonoscopy carries some risks: perforation, bleeding, and respiratory depression due to sedation. While uncommon, the risks associated with optical colonoscopy are the highest of all screening methods, and the risks cannot be ignored as the test is to be used to screen large numbers of asymptomatic patients.

CTC can provide a completely non-invasive alternative to optical colonoscopy for colon cancer screening. Although bowel cleansing is still required, we are actively investigating image processing methods that can eliminate this inconvenience and discomfort as well. We are also developing other advances in CTC technology, including methods to reduce scan interpretation times and more effective visualization techniques to assist radiologists in reading the large volume of data (300-500 CT images) associated with each scan. Our work also includes development of new three-dimensional rendering methods that allow rendering to be performed on desktop computers rather than dedicated workstations.

Our technique will enable the viewer to virtually “fly” through the three-dimensional image volume, as well as provide a compact format for archival purposes. Our work on this important advance in health care screening is being performed in conjunction with our medical partners at both Boston University and Dartmouth-Hitchcock Medical Center.

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