Endosteal and periosteal blood flow quantified with dynamic contrast-enhanced fluorescence to guide open orthopaedic surgery

Abstract

Due to the lack of objectively measurable or quantifiable methods to assess the bone perfusion, the success of removing devitalized bone is based almost entirely on surgeon's experience and varies widely across surgeons and centers. In this study, an indocyanine green (ICG)-based dynamic contrast-enhanced fluorescence imaging (DCE-FI) has been developed to objectively assess bone perfusion and guide surgical debridement. A porcine trauma model (n = 6 pigs × 2 legs) with up to 5 conditions of severity in loss of flow in each, was imaged by a commercial fluorescence imaging system. By applying the bone-specific hybrid plug-compartment (HyPC) kinetic model to four-minute video sequences, the perfusion-related metrics, such as peak intensity, total bone blood flow (TBBF) and endosteal bone blood flow to TBBF fraction (EFF) were calculated. The results shown that the combination of TBBF and EFF can effectively differentiate injured from normal bone with the accuracy, sensitivity and specificity of 89%, 88% and 90%, respectively. Our subsequent first in human bone blood flow imaging study confirmed DCE-FI can be successfully translated into human orthopaedic trauma patients.

Keywords: Boon blood flow; Dynamic contrast-enhanced fluorescence imaging; Indocyanine green; Orthopedic surgery; porcine trauma model.

Figure 1:

Schematic sketch of ICG fluorescence imaging from filtered emission.

Figure 2:

Regions of interest (ROI). The area sizeof each ROI is about 10 mm length along the bone.P2 and P1 are the ROIs at proximal ends towards body, t is in the area that being osteotomized, and d1 and d2 are in the distal end of the tibia.

Figure 3:

Depiction of bone-specific kinetic model.

Figure 4:

ICG fluorescence map overlay on the white light bone images as well as temporal dynamic curves of the ICG kinetics in the ROI. (a) baseline, (b) after double diaphyseal osteotomies, (c) half circumferential soft tissue stripping from the proximal bone close to the previous cut, (d) full circumferential soft tissue stripping from the proximal end, and (e) all circumferential soft tissue stripping to disrupt both periosteal and endosteal blood supply from entire tibia.