Using PET/CT Bone Scan Dynamic Data to Evaluate Tibia Remodeling When a Taylor Spatial Frame Is Used: Short and Longer Term Differences

Abstract

Eighteen consecutive patients, treated with a Taylor Spatial Frame for complex tibia conditions, gave their informed consent to undergo Na18F−PET/CT bone scans. We present a Patlak-like analysis utilizing an approximated blood time-activity curve eliminating the need for blood aliquots. Additionally, standardized uptake values (SUV) derived from dynamic acquisitions were compared to this Patlak-like approach. Spherical volumes of interest (VOIs) were drawn to include broken bone, other (normal) bone, and muscle. TheSUVm(t)(m=max, mean) and a series of slopes were computed as(SUVm(ti)-SUVm(tj))/(ti-tj), for pairs of time valuestiandtj. A Patlak-like analysis was performed for the same time values by computing((VOIp(ti)/VOIe(ti))-(VOIp(tj)/VOIe(tj)))/(ti-tj), wherep= broken bone, other bone, and muscle ande= expected activity in a VOI. Paired comparisons between Patlak-like andSUVmslopes showed good agreement by both linear regression and correlation coefficient analysis (r=84%,rs=78%-SUVmax,r=92%, andrs=91%-SUVmean), suggesting static scans could substitute for dynamic studies. Patlak-like slope differences of 0.1 min−1or greater between examinations andSUVmaxdifferences of ~5 usually indicated good remodeling progress, while negative Patlak-like slope differences of −0.06 min−1usually indicated poor remodeling progress in this cohort.