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. The SUVm(t) (m = max, mean) and a series of slopes were computed as (SUVm(t i) − SUVm(t j))/(t i − t j), for pairs of time values t i and t j. A Patlak-like analysis was performed for the same time values by computing ((VOIp(t i)/VOIe(t i))−(VOIp(t j)/VOIe(t j)))/(t i − t j), where p = broken bone, other bone, and muscle and e = expected activity in a VOI. Paired comparisons between Patlak-like and SUVm slopes showed good agreement by both linear regression and correlation coefficient analysis (r = 84%, r s = 78%-SUVmax, r = 92%, and r s = 91%-SUVmean), suggesting static scans could substitute for dynamic studies. Patlak-like slope differences of 0.1 min−1 or greater between examinations and SUVmax differences of ~5 usually indicated good remodeling progress, while negative Patlak-like slope differences of −0.06 min−1 usually indicated poor remodeling progress in this cohort.

Can Spatiotemporal Fluoride (18F−) Uptake be Used to Assess Bone Formation in the Tibia? A Longitudinal Study Using PET/CT

“…An important point shown in this study and in previous studies [25, 26] is that 18 F − bone scans can provide semiquantitative and qualitative functional information regarding bone formation in each part of the bone [5, 14, 37]. The current study shows that, in clinical practice, there are numerous situations in which a functional (or biologic or metabolic) assessment of bone formation may be of value.…”

“…5), which implies that one cannot simply look at the value of SUVmaxDPD, but rather also must examine spatiotemporal uptake. Moreover, this study showed the potential advantages of dynamic and static PET acquisition, because this allowed the semiquantitative analysis used in an earlier study [25] and the reconstruction of short-duration volumes to observe the dynamics of 18 F − uptake as was done in the current study.…”

“…Forty-five minutes was chosen because this was a reasonable amount of time for the patient to lie still. Then, to capture the maximum uptake in bone, a 5-minute static scan was performed after 60 minutes [25, 26, 36]. A series of volumes was reconstructed for each patient, comprising five volumes at 1-minute intervals (thus the first 5 minutes postinjection), five at 3-minute intervals, three at 5-minute intervals, and one at 10 minutes later, totaling 45 minutes.…”

Can Na18F PET/CT bone scans help when deciding if early intervention is needed in patients being treated with a TSF attached to the tibia: insights from 41 patients

“…This is contrasted with the data from a patient not needing revision. The proposed method extends the earlier analyses using spatiotemporal movies derived from the dynamic scans, static scans, and the PET uptake data [10][11][12]. The graphical methods introduced here and additional data, some of which are described in ESM 1 for each of our patients, could be used by the orthopedic surgeon to determine if the treatment should continue uninterrupted or if a course of intervention should be followed.…”