Intraoperative fluorescence perfusion assessment should be corrected by a measured subject-specific arterial input function

Abstract

Significance: The effects of varying the indocyanine green injection dose, injection rate, physiologic dispersion of dye, and intravenous tubing volume propagate into the shape and magnitude of the arterial input function (AIF) during intraoperative fluorescence perfusion assessment, thereby altering the observed kinetics of the fluorescence images in vivo. Aim: Numerical simulations are used to demonstrate the effect of AIF on metrics derived from tissue concentration curves such as peak fluorescence, time-to-peak (TTP), and egress slope. Approach: Forward models of tissue concentration were produced by convolving simulated AIFs with the adiabatic approximation to the tissue homogeneity model using input parameters representing six different tissue examples (normal brain, glioma, normal skin, ischemic skin, normal bone, and osteonecrosis). Results: The results show that AIF perturbations result in variations in estimates of total intensity of up to 80% and TTP error of up to 200%, with the errors more dominant in brain, less in skin, and less in bone. Interestingly, error in ingress slope was as high as 60% across all tissue types. These are key observable parameters used in fluorescence imaging either implicitly by viewing the image or explicitly through intensity fitting algorithms. Correcting by deconvolving the image with a measured subject-specific AIF provides an intuitive means of visualizing the data while also removing the source of variance and allowing intra-and intersubject comparisons. Conclusions: These results suggest that intraoperative fluorescence perfusion assessment should be corrected by patient-specific AIFs measured by pulse dye densitometry.

Quantitative dynamic near-infrared fluorescence imaging using indocyanine green for analysis of bowel perfusion after mesenteric resection

“…It is suggested that correcting for arterial input function by pulse dye densitometry could improve the currently used quantification methods by reducing the intra-and inter-subject variability. 19 Furthermore, fluorescence imaging can be combined with other methods such as endogenous functional imaging of oxygenation or blood perfusion to increase the capabilities of optical imaging to guide surgery reliably and in real time. 20,21 This report demonstrates the difficulties of visual assessment of fluorescence perfusion imaging in patients with potentially compromised bowel segment following partial mesenteric excision.…”

Perspective on optical imaging for functional assessment in musculoskeletal extremity trauma surgery

“…What is needed is an intraoperative system that can assess vascular perfusion of bone in the surgical field in real-time, which could guide surgeons in the right amount of bone and soft tissue to debride. Although there are challenges in association with the three-dimensional (3-D) nature of traumatic wounds and open fractures, optical imaging techniques 44 , 45 are uniquely suited to collect data on the inflow/outflow kinetics of complex tissues.…”

“…However, optical imaging systems are uniquely suited to assess perfusion of bone and deep soft tissues in operating room settings in real-time. 27 , 44 , 45 , 49 …”

“…Recently, the flow assessment of imaging the fluorescence from ICG has been shown to provide predictive value for flow and even potentially differentiate between endosteal and periosteal flow. 27 , 44 , 45 , 49 …”

“…Biological functions such as regrowth or necrosis have two very different sampling scales, either microscopic methods such as UV and antibiotic fluorescence or macroscopic tools such as NIRS and contrast agent fluorescence. 27 , 44 , 45 , 49 Again, for most clinical issues, the sampling of macroscopic signals is likely needed, and the combination with existing clinical tools such as ultrasound or x-ray would be beneficial.…”