Bone Turnover in Patients with Chronic Kidney Disease Stage 5D and Healthy Controls — a Quantitative [¹⁸F]Fluoride PET Study

Background: Chronic kidney disease (CKD) is prevalent in the aging population and increases the risk of fracture 2–4 times. We compared optimized quantitative [¹⁸F]fluoride PET/CT methods to the reference standard with arterial input function (AIF) to identify a clinically accessible method for evaluation of bone turnover in patients with CKD. Methods: Ten patients on chronic hemodialysis treatment and ten control patients were recruited. A dynamic 60-min [¹⁸F]fluoride PET scan was obtained from the 5th lumbar vertebra to the proximal femur simultaneously with arterial blood sampling to achieve an AIF. Individual AIFs were time-shifted to compute a population curve (PDIF). Bone and vascular volumes-of-interest (VOIs) were drawn, and an image-derived-input-function (IDIF) was extracted. PDIF and IDIF were scaled to plasma. Bone turnover (K_i) was calculated with the AIF, PDIF, and IDIF and bone VOIs using a Gjedde-Patlak plot. Input methods were compared using correlations and precision errors. Results: The calculated K_i from the five non-invasive methods all correlated to the K_i from the AIF method with the PDIF scaled to a single late plasma sample showing the highest correlations (r > 0.94), and the lowest precision error of 3–5%. Furthermore, the femoral bone VOI’s correlated positively to p-PTH and showed significant differences between patients and controls. Conclusions: Dynamic 30 min [¹⁸F]fluoride PET/CT with a population based input curve scaled to a single venous plasma sample is a feasible and precise non-invasive diagnostic method for the assessment of bone turnover in patients with CKD. The method may potentially allow for earlier and more precise diagnosis and may be useful for assessment of treatment effects, which is crucial for development of future treatment strategies.