Figure 1.
Quantitative description of infection status in each experimental group.
Quantitative histological and radiological analyses were done as previously described [14] with the results reported as the average ± the standard deviation for the infected (Inf) and uninfected (Cont) groups. Histological results were obtained only at the completion of the experiment while X-ray studies were performed at both 7 and 14 days.
Figure 2.
Representative X-ray and FDG-PET images.
Representative X-rays of the surgical site are shown for infected and uninfected rabbits as a function of time after surgery. Summed FDG-PET images below each X-ray illustrate uptake in both the surgical (R, surgical site illustrated by bracket) and non-surgical limbs (L) in an infected and an uninfected animal. “Regions of interest” (ROIs) used for measurement of SUV in each limb are illustrated by the circles.
Figure 3.
Uptake in the surgical (top) vs non-surgical limb (bottom) is shown for the infected and uninfected control groups as a function of time after the administration of FDG. Results for each group obtained 7 and 14 days after surgery are shown as the average SUVmax (solid line) ± one standard deviation from the mean (shaded regions). Results represent the averages ± standard deviations obtained after combining all experimental animals in the 1st and 2nd trials (see text).
Figure 4.
Uptake of FDG over time as a function of SUR.
The ratio of SUVmax in the surgical vs. non-surgical limbs (SUR) was plotted as a function of time after the administration of FDG. Results for the infected and uninfected control groups 7 and 14 days after surgery are shown as the average SUVmax (solid line) ± one standard deviation from the mean (shaded regions). Results represent the averages ± standard deviations obtained from the 3rd experimental trial. Arrows along the axes indicate the timepoint (bottom) and SUR (left) at which the greatest discrimination between the two groups was observed.
Table 1.
Diagnostic parameters as a function of FDG-PET evaluation model.
Figure 5.
Confirmation of optimal 7 day diagnostic parameters.
Left: Results illustrate the number of 1000 randomly-generated datasets in which the indicated timepoint after the administration of FDG exhibited maximum discrimination between the infected and uninfected experimental groups. Right: Results illustrate the proportion of “cut-off” ratios (surgical vs. non-surgical limb) that exhibited optimal discrimination at the alternative timepoints shown. Note that >850 of 1000 “iterations” found the optimum timepoint to be 11 minutes after administration of FDG (left) and that the optimal SUR cutoff in the majority of these was ∼1.27.
Figure 6.
Identification of optimal 14 day diagnostic parameters.
Left: Results illustrate the number of 1000 randomly-generated datasets in which the indicated timepoint after the administration of FDG exhibited maximum discrimination between the infected and uninfected experimental groups. Right: Results illustrate the proportion of “cut-off” ratios (surgical vs. non-surgical limb) that exhibited optimal discrimination at the alternative timepoints shown. Note that the number of “iterations” in which the greatest discrimination was observed were comparable when the assay was done 57 or 85 minutes after the administration of FDG and that the optimal SUR cutoff differed between these two timepoints.
Figure 7.
Best classifiers of infection status at week 1 and week 2 for all data.
Classifiers of infection status over 1000 iterations are plotted, with frequency of classifier identification as the best in any given iteration indicated by size of the dot for that classifier. On day 7, the 5 best classifiers all occurred when t1 = 0; that is, at a single timepoint SUR, with the single best classifier being <15 min after the administration of FDG. On day 14, all but one (δSUV at t1 = 15 min and t2 = 40 min) of the 5 best classifiers of infection status were a single timepoint SUR, with the single best classifier being >85 min after the administration of FDG.