New device early neoplastic changes in colon

A novel technology reveals early changes in the microvasculature of endoscopically normal colonic mucosa, a finding that may be a biomarker for neoplasia risk, report in an article appearing in the October 2008 issue of Gastroenterology.

Detection of a small early increase in blood supply (EIBS) throughout the colon and larger increases near a future lesion, could alert physicians that they should further evaluate a particular patient.

To evaluate the clinical applicability of EIBS, assessed 22 patients undergoing a screening colonoscopy at the Evanston Hospital in Evanston, Ill. Their mean age was 57 years, and 40% were women.

After intubation to the cecum, the new device, polarization-gated spectroscopic probe, was inserted. About 10 measurements were taken of from mucosa that appeared normal on endoscopy in the cecum, midtransverse colon, and rectum; 175 patients had no adenomas detected, 35 had nonadvanced adenomas, and 12 had advanced adenomas.

The device uses four-dimensional, elastic, light-scattering fingerprinting technology that quantifies colonic mucosal microvasculature. The probe can be inserted through an endoscope.

In this study, the researchers were able to quantify total hemoglobin, oxygenated hemoglobin (OHb), and deoxygenated hemoglobin (DHb) using spectrometry.

If an operator detected a polyp during colonoscopy, the probe was used to take Ohb and DHb readings from the polyp and also readings at a distance less than 10 cm and 10-30 cm proximal and distal to the lesion.

The magnitude of the EIBS was directly related to proximity to the neoplasia. For example, total hemoglobin concentration was 75% higher at an adenoma site, compared with a comparable region in a patient not harboring an adenoma. Readings taken at sites 10-30 cm from an adenoma had a significant increase in total hemoglobin, OHb, and DHb. With increasing distance from the lesion, these concentrations gradually decreased.

Significantly higher hemoglobin concentrations were measured at the sites of advanced adenomatous polyps, compared with nonadvanced adenomas. Although larger advanced adenomas displayed the greatest EIBS, the researchers noted that even small adenomatous polyps manifested some increased blood supply. “This suggests that EIBS may have both biological and clinical significance.”

The researchers even found that EIBS measured 30 cm away from a lesion was “reasonably accurate” in detecting advanced adenomas (sensitivity, 92%; specificity, 78%; negative predictive value, 99.7%; positive predictive value, 9.4%). However, “these estimates should be viewed cautiously as they are based on relatively modest patient numbers.”

Microvascular blood content was increased in uninvolved mucosa in patients with both advanced and nonadvanced adenomas, whereas patients with nonneoplastic lesions did not demonstrate EIBS in uninvolved mucosa. In theory, EIBS could serve as an “optical biopsy” to distinguish between adenomas and hyperplastic polyps.

Study limitations include the fact that measurements of distance in the colon can be inaccurate because of colonoscope looping. Also, estimation of polyp size with endoscopy can be inaccurate.