Fp584correlation Between 18fluorine Positron Emission Tomography and Bone Histomorphometry in Dialysis Patients

Abstract

The diagnosis and differentiation of the subtypes of chronic kidney disease-mineral and bone disorder (CKD-MBD) are challenging. The golden standard of diagnosis is bone biopsy, but it is invasive and not available in every center. 18 Fluorine isotope is a PET-tracer, which incorporates into the bone at sites of high metabolic activity, triggered by osteoblast and osteoclast activity. The aim of this study is to evaluate if 18 F-PET imaging correlates with the metabolic activity of bone in dialysis patients, as assessed by the histomorphometry of bone biopsy. METHODS: 21 dialysis patients underwent a dynamic 18 F-positron-emission-tomography (PET)-scan (L1-L4) and a bone biopsy. The bone biopsy was taken from the iliac spine vertically after double labelling with tetracycline within one month after the PETscan. The PET-scan was analyzed using graphical Patlak model and K i was measured. K i is the bone plasma clearance of 18 Fluor, which reflects 18 Fluor activity in the bone. As histomorphometrics parameters to detect metabolic activity in bone we used BFR (bone formation rate) ¼ mineral apposition rate (MAR) x mineralizing surface/bone surface (MS/BS), Oc.S/BS (osteoclast surface/bone surface), ES/BS (erosion surface/ bone surface) and Ob.S/BS (osteoblast surface/bone surface) RESULTS: As shown in Figure1 there was a statistically significant correlation between 18 Fluor-activity and BFR (p¼0.001, r s ¼ 0.66), Oc.S/BS (p¼0.003, r s ¼ 0.61) and ES/BS (p¼0.001, r s ¼ 0.66). There was a less significant correlation between 18 Fluor-activity and Ob.S/BS (p¼0.03, r s ¼ 0.47). As expected, there was no correlation between 18 Fluor acitivity and bone volume (p¼0.44) and trabecular thickness (p¼0.92). CONCLUSIONS: The results indicate that bone metabolism can readily be measured using 18 F-PET-imaging and that 18 F-PET-scan correlates with bone histomorphometry in dialysis patients with renal osteodystrophy. 18 F-PET-imaging looks promising as a diagnostic tool to evaluate dialysis patients with CKD-MBD. Studies are in progress to evaluate the feasibility of 18 F-PET-imaging in ND-CKD 5 and kidney transplantation patients.