Dynamic contrast-enhanced fluorescence imaging compared with MR imaging in evaluating bone perfusion during open orthopedic surgery

Abstract

ICG-based dynamic contrast-enhanced fluorescence imaging (DCE-FI) and intraoperative DCE- magnetic resonance imaging (MRI) have been carried out nearly simultaneously in three lower extremity bone infection cases to investigate the relationship between these two imaging modalities for assessing bone blood perfusion during open orthopedic surgeries. Time-intensity curves in the corresponding regions of interest of two modalities were derived for comparison. The results demonstrated that ICG-based DCE-FI has higher sensitivity to perfusion changes while DCE-MRI provides superior and supplemental depth-related perfusion information. Research applying the depth-related perfusion information derived from MRI to improve the overall analytic modeling of intraoperative DCE-FI is ongoing.

Keywords: bone vascular perfusion; dynamic contrast-enhanced fluorescence imaging; dynamic contrast-enhanced magnetic resonance imaging; indocyanine green; open orthopedic surgery; time-intensity curve.

Figure 1.

MR and fluorescence images of case #3, a 52-year-old male s/p surgical fixation of pilon fracture complicated by fracture-related infection, and their TICs of corresponding ROIs. (a) Sagittal DCE-MRI 3D VIBE image of the tibia; (c) FI overlaid on the white light image of the surgical view; (b, d) TICs of the ROIs obtained from DCE-MRI (a) and DCE-FI (c). Pink and blue ROIs represent infected and more normal bone areas, respectively. The ROIs from MRI and FI are co-registered with MRI fiducials placed around the surgical incision (c).

Figure 2.

Axial reformat of 3D VIBE DCE-MRI of the tibia and TICs from case #1, a 66-year-old male s/p surgical fixation of pilon fracture complicated by fracture-related infection. (a) The sagittal 3D VIBE DCE-MRI data was reformatted into the axial plane, and 4 ROIs were placed at superficial callus (purple), deep callus (red), superficial marrow (orange) and deep marrow (green); (b) TICs of the 4 ROIs in DCE-MRI, showing a decline of bone perfusion with an increasing depth between superficial callus and deep marrow; (e) TIC of the corresponding ROI in DCE-FI.