A MR image of the plated canine femoral osteotomy demonstrates the ROIs for DCE-MRI. A T1-weighted postcontrast coronal MR image of the plated canine femoral osteotomy obtained at baseline is shown and is representative of the MRI at 3- and 6-week postoperative scans. The red circle in the bone marrow at the osteotomy and the blue circle in the adjacent muscle indicate the ROIs examined by DCE-MRI and correspond to the graphs depicted in Fig. 2.

Quantitation of cortical bone and vascular volume via CB-CT with micro-CT validation. The left femur of a canine cadaver was infused with iodine contrast and subjected to three CB-CT scans. (A) The primary data were manipulated to subtract the metal artifacts and reconstruct the ROI, which is the bone tissue directly under the plate. These data (CB-CT1) were then used to quantify the cortical bone and vascular volume (mm³)/graft length (72.3 mm) and are presented as the mean ± standard deviation in Table 1. (B) The plate and screws were then removed, and the cadaver was rescanned three times, and the data were processed by automated analyses without manual manipulation. These data were then used to identify the (C) bone and (D) iodine contrast and the quantified volume/graft length are presented as CB-CT2 for each in Table 1. To validate the CB-CT bone volume measurements, we scanned the femur without the implant in a Scanco micro-CT 40, which is validated to 35-μm resolution. (E) A reconstructed 3D image of the femur from the micro-CT scan is shown to demonstrate the gross similarity to the CB-CT reconstructed image in (C). Unfortunately, the iodine contrast could not be preserved to validate the vascular volume. These results demonstrated all CB-CT measurements have a reproducibility error of less than 1.5% and an accuracy error of less than 2.6% versus micro-CT.

Longitudinal DCE-MRI of a plated canine femoral osteotomy demonstrates revascularization over time. The graphs show the increase in T1 signal intensity (SI) of bone marrow and muscle through time during and after intravenous contrast injection from the DCE-MRI taken of the ROIs described in Fig. 1. Arrows indicated the delivery of the intravenous contrast. Of note is the lack of enhancement in signal intensity of the bone marrow ROI (red) after intravenous contrast at (A) baseline versus the marked increase seen at (B) 3 weeks postoperatively and (C) 6 weeks postoperatively. Compare to the relatively consistent increase in signal intensity of muscle ROI (blue) at all time points. Bone marrow Ktrans values (min⁻¹) were 0.0034, 0.0405, and 0.0425, respectively, for the three time points.

CB-CT volumetric segmentation of a tibial composite allograft in a patient two weeks and eight months after reconstructive surgery. Radiology of the patient’s composite allograft obtained at 2 weeks (A–C) and 8 months (D–F) postoperative are shown. Standard radiographs (A, D), 2D CB-CT slices (B, E) and reconstructed 3D images of the patient’s composite allograft are shown with anteroposterior views. Of note is the lack of remarkable findings in the radiographs including a similar gap at the allograft-host junction, versus the radiographic evidence of bony union (E) and the bridging bone callus (F). These CB-CT data were also used for volumetric segmentation, which demonstrated a −5.4% change in allograft bone volume (blue: 98932.6 mm³ vs. 34367.0 mm³), a +4.5% change in tibia bone volume (green: 30139.8 mm³ vs. 23554.0 mm³), while the volume of the, compression plate and screws was unchanged (yellow: 5347.0 mm³ vs. 5379.0 mm³).