tailieunhanh - Carcinoma of the Esophagus - part 4

nội soi thông thường [58]. Cả hai nghiên cứu có tỷ lệ dương tính giả cao 78 và 87%, tương ứng, tuy nhiên, cả những nghiên cứu này sử dụng một hệ thống thông tin AFI cũ chụp từ ánh sáng phản xạ sử dụng cáp quang nội soi với những hình ảnh | 38 A. M. Lennon and I. D. Penman a b Figure a Normal green mucosal appearance in autofluorescence AFI imaging. b Early carcinoma is seen as a pink magenta area arrows using autofluorescence. conventional endoscopy 58 . Both these studies had high false-positive rates of 78 and 87 respectively however both these studies used an older AFI system capturing information from reflected light using fiberoptic endoscopes with low-quality images. Using a newer videoendoscopic AFI system it has been possible to identify HGD or early cancer in 6 of 21 patients with Barrett s esophagus that was not identified using conventional endoscopy 59 . Again there was a high falsepositive rate of 50 . The authors therefore compared the performance of AFI in combination with NBI in 20 patients with Barrett s esophagus and suspected or confirmed HGIN 60 . AFI identified 47 suspicious lesions of which 28 had HGIN and 19 40 were false positive. In these latter 19 cases the use of NBI correctly identified 14 as nondysplastic reducing the overall false-positive rate to 10 . This study suggests that combining AFI and NBI may increase the accuracy of detecting HGIN in Barrett s esophagus. Larger controlled studies are awaited and refinements in technology may further improve these impressive early results. Other modalities A number of other endoscopic modalities have shown promise in the detection of early neoplasia. In Raman spectroscopy light can be absorbed or scattered as it Recent Advances in the Endoscopic Diagnosis of Esophageal Cancer 39 interacts with tissue molecules. Almost all of the scattered light is the same wavelength as the incidence light however a small fraction undergoes Raman scattering in which slight shifts in energy and wavelength occur because of exchange of energy with the molecular structure. These wavelength shifts correspond to specific vibrations of the interacting molecule. A Raman spectrum is a plot of the intensity of the scattered light as a function of the