Background and study aims: To compare the rate of detection of colorectal neoplastic lesions using the selective photosensitizer precursor hexaminolevulinate (HAL) combined with a new fluorescence video endoscope system against that of standard white light endoscopy, and secondarily, to evaluate the safety profile of HAL-induced fluorescence colonoscopy.
Patients and methods: This prospective phase II clinical pilot study from two hospital study centers included 25 patients with known or highly suspected colorectal neoplasia. They underwent sensitization with locally applied 500 ml HAL enemas at a concentration of 1.6 mmol/L. At 60 minutes after enteral HAL administration, fluorescence imaging was done using a special light source capable of delivering either white light or blue excitation light. Red fluorescence induced by illumination with blue light was detected via a prototype fluorescence video colonoscope. Biopsies were taken from suspicious areas found with white or blue light.
Results: Using histology as the gold standard, 55 / 93 of neoplastic lesions were detected with white light endoscopy, 53 / 93 with both white and blue light, 38 / 93 with blue light and second-pass white light, and 27/93 with blue light only. Of all neoplastic lesions, 91 / 93 revealed red fluorescence under fluorescence imaging ( P < 0.0001). Fluorescence mode showed 38.7 % (36 / 93) more neoplasms than did white light endoscopy. An isolated slight elevation of bilirubin, by a factor of 1.5, was noted after the administration of HAL.
Conclusions: Administration of HAL as enema induces selective lesion fluorescence and increases lesion detection rate in patients with colorectal neoplasia, especially of flat, nonvisible adenomas.
Georg Thieme Verlag KG Stuttgart. New York.