 
         
         
         
         
            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.
         
         
    
   
      
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B. MayingerMD, PhD 
            Department of Medicine II
Hospital Munich-Pasing
            
            Steinerweg 5
D-81241 Munich
Germany
            
            Fax: +49-89-88922411
            
            eMail: brigitte.mayinger@krankenhaus-pasing.de