Background: FLOW(R)800 delivers a color-coded map for snapshot visualization of the temporal distribution dynamics after indocyanine green angiography (ICG-A) with post-hoc calculation of FLOW(R)800-specific hemodynamic parameters. However, the value of these parameters regarding quantitative flow assessment remains unclear.
Objective: To determine the value of FLOW(R)800-specific hemodynamic parameters in neurosurgical patients that permit assessment of hemodynamic changes within the micro- and macrocirculation.
Methods: FLOW(R)800 was performed in 25 patients undergoing superficial temporal artery to middle cerebral artery (STA-MCA) bypass grafting and in 5 patients undergoing high or intermediate flow bypass (H/IFBP) grafting. The time to half maximum fluorescence (t1/2max) and the cerebral blood flow index (CBFi) were calculated in the recipient vessel (macrocirculation) and the cortical territory (microcirculation) surrounding the anastomosis. For further evaluation, FLOW(R)800-specific hemodynamic parameters were compared to cortical Laser Speckle Imaging (LSI) and quantitative doppler flow within the graft.
Results: FLOW(R)800 provided color-coded information on the temporo-spatial distribution dynamics of the dye with excellent assessment of bypass patency. In the recipient vessel and in the cortical territory surrounding the anastomosis, FLOW(R)800 detected hemodynamic changes after STA-MCA bypass grafting in terms of a significant decrease of t1/2max and increase of CBFi. Interestingly, comparison of t1/2max to semiquantitative LSI-specific cortical perfusion within the microcirculation demonstrated poor agreement and neither t1/2max nor CBFi within the graft correlated with quantitative graft flow assessed by doppler.
Conclusion: FLOW(R)800 may detect procedure-related hemodynamic changes within the micro- and macrocirculation, but should not be used as a stand-alone tool for quantitative flow assessment.
From: FLOW(R)800 Allows Visualization of Hemodynamic Changes After Extra- to Intracranial Bypass Surgery But Not Assessment of Quantitative Perfusion or Flow by Prinz et al.