Predictors of indocyanine green visualization during fluorescence imaging for segmental plane formation in thoracoscopic anatomical segmentectomy

Background: To determine factors predicting indocyanine green (ICG) visualization during fluorescence imaging for segmental plane formation in thoracoscopic anatomical segmentectomy. Methods: Intraoperatively, the intravenous ICG fluorescence imaging system during thoracoscopic anatomical segmentectomy obtained fluorescence emitted images of its surfaces during lung segmental plane formation after the administration of 5 mg/body weight of ICG. The subtraction of regularization scale for calculating the exciting peaks of ICG between the planned segments to resect and to remain was defined as ΔIntensity (ΔI). Variables such as the ratio of forced expiratory volume in 1 s to forced vital capacity (%FEV_1.0), smoking index (SI), body mass index (BMI), and low attenuation area (LAA) on computed tomography (CT) took a leading part. Results: The formation of the segmental plane was successfully accomplished in 98.6% segments and/or subsegments. SI and LAA significantly affected ΔI levels. The area under the receiver operating characteristic curve for the %FEV_1.0, SI, and LAA was 0.56, 0.70, and 0.74, respectively. SI > 800 and LAA > 1.0% were strong predictors of unfavorable ICG visibility (P=0.04 and 0.01, respectively). Conclusions: Fluorescence imaging with ICG was a safe and effective method for segmental plane formation during thoracoscopic anatomical segmentectomy. In spite of its high success rate, unfavorable visibility may potentially occur in patients who are heavy smokers or those with a LAA (> 1.0%) on CT.