Noninvasive measurement of oxygen saturation of the microvascular blood in Barrett's dysplasia by use of optical spectroscopy
Background: Current investigations into endoscopic screening for the early detection of Barrett's esophageal adenocarcinoma have focused on visualization of the microvascular morphology by using narrow-band imaging (NBI). Adjustment of the center wavelength, particularly of the NBI blue imaging filter, may lead to improved image contrast, depending on the oxygen saturation of the microvascular blood of dysplastic and early cancerous Barrett's mucosa. Objective: To perform in vivo, noninvasive measurements of the oxygen saturation of the microvascular blood for different pathologic grades of Barrett's mucosa by using differential path-length spectroscopy (DPS). Design: DPS measurements were made on normal (n = 7), low-grade dysplastic (n = 10), high-grade dysplastic (n = 7), and cancerous (n = 4) Barrett's mucosa by using a fiber-optic probe, and were correlated to the histologic outcome of biopsy specimens taken from the same location. Setting: Academic medical center. Patients: Fifteen patients with Barrett's esophagus who were undergoing gastroscopy. Interventions: Biopsy specimens were taken from suspicious areas in the esophagus. Main Outcome Measurements: The oxygen saturation of the microvascular blood of different pathologic grades of Barrett's mucosa was assessed. Results: The oxygen saturation of the microvascular blood remains high (approximately 90%) throughout the metaplasia-dysplasia-adenocarcinoma sequence. Limitation: The small number of patients. Conclusions: The current NBI blue imaging filter, centered on the peak absorption of oxyhemoglobin (415 nm), is well chosen, and little improvement in image contrast is to be expected from changes in this center wavelength.