Visible and near‑infrared interactance spectroscopy is a non‑invasive technique which can be used to evaluate the hemoglobin concentration in endometriotic cyst fluid

Abstract

Hemoglobin concentrations in endometriotic cyst fluids have been found to be associated with distinct clinical manifestations, such as pelvic pain and infertility, as well as with malignant transformation. However, the measurement of the hemoglobin concentration in cyst fluid is an invasive procedure. The present study aimed to evaluate the usefulness of visible and near‑infrared interactance spectroscopy as a non‑invasive technique for estimating the hemoglobin concentration in endometriotic cystic fluid. Optical fibers were directly placed onto sliced raw pork (up to 10‑mm‑thick as an anatomical barrier on the cyst's surface) that covers a cuvette containing hemoglobin solution or endometriotic cyst fluid. Partial least square regression based on the second derivative using visible and near‑infrared interactance spectroscopy (wavelength region, 500‑1,200 nm) was used to estimate the hemoglobin concentration. The samples were categorized into the evaluation sets (i.e., calibration set) to create calibration curves and test sets (i.e., validation set) to validate equations. The cyst fluid at 5 mm of pork thickness achieved a high correlation between actual and predicted hemoglobin concentrations (calibration (R2=0.977) and validation (R2=0.874) data). However, the correlation slightly decreased at 10‑mm pork thickness (i.e., calibration (R2=0.979) and validation (R2=0.580) data). Interactance spectroscopy may thus be a non‑invasive tool which can be used to estimate the hemoglobin concentration in endometriotic cyst fluid when the anatomical barrier is 5 mm. This technology is a reliable modality for predicting the severity of dysmenorrhea and infertility, as well as malignant transformation, in a number of patients with endometriotic cysts. Such quantitative optical spectroscopic imaging technologies may enable the accurate diagnosis of the pathological processes in endometriotic cysts in clinical practice.