Evaluation of Hemodynamic Change by Indocyanine Green-FLOW 800 Videoangiography Mapping: Prediction of Hyperperfusion Syndrome in Patients with Moyamoya Disease

Objective. Hyperperfusion syndrome (HPS) after bypass surgery for moyamoya disease (MMD) mainly results from redistribution of blood flow, which leads to poor outcomes, while effective methods to predict HPS are still lacking. Indocyanine green (ICG) videoangiography can assess regional cerebral blood flow changes semiquantitatively with the application of FLOW 800 software. The purpose of this study was to investigate whether the intraoperative evaluation of local hemodynamic changes around anastomotic sites using FLOW 800 videoangiography mapping can predict the incidence of HPS and clinical outcomes. Methods. Of the patients who were diagnosed with MMD in our hospital between August 2018 and December 2019, who underwent superficial temporal artery-middle cerebral artery bypass surgeries, we investigated 65 hemispheres (in 62 patients) in which intraoperative ICG analysis was performed using FLOW 800 (Zeiss Meditec, Oberkochen, Germany) to evaluate the local cerebral hemodynamics before and after anastomosis. Regions of interest were set at more than 2 points on the brain surface according to the location and situation of recipient arteries in the surgical area. Peak cerebral blood volume (CBV), regional cerebral blood flow (CBF), and time to peak (TTP) were calculated from the selected points. As the data were available intraoperatively, anastomoses were performed in a suitable area. According to the occurrence of HPS, patients were divided into the asymptomatic and symptomatic groups, from which hemodynamic parameters were compared. Furthermore, ROC analysis was performed to determine the diagnostic accuracy of change rates in CBV, CBF, and TTP (i.e., Delta CBV, Delta CBF, and Delta TTP) for predicting HPS. Results. Data from the 62 patients were analyzed, and all patients were closely assessed during hospitalization after the procedures. The values of Delta CBV and Delta CBF were significantly higher in the symptomatic group (p<0.01), while Delta TTP is slightly lower in the symptomatic group with no statistical differences (p=0.72). Hemodynamic parameters including Delta CBV and Delta CBF, calculated by FLOW 800, had high sensitivity and specificity according to the ROC curve (Delta CBV:AUC=0.743, 95% CI, 0.605-0.881,p=0.002; Delta CBF:AUC=0.852, 95% CI, 0.750-0.954,p<0.01), which could be used as predictors for HPS. Conclusions. Intraoperative ICG-FLOW 800 videoangiography mapping is a safe method which can reflect hemodynamic characteristics in the surgical area for MMD, the findings of which correlate with the occurrence of HPS. Parameters including Delta CBV and Delta CBF are proven to be efficient in the prediction of HPS.