Plasma Soluble Urokinase Plasminogen Activator Receptor in Children with Urinary Tract Infection

Objective In this prospective study we investigated the role of plasma levels of soluble urokinase plasminogen activator receptor (suPAR) in children with urinary tract infection. Material and Methods We measured the levels of plasma suPAR during admission in 42 children with suspected acute pyelonephritis and compared the results to acute DMSA scintigraphy. Results The mean level of plasma suPAR at admission was significantly elevated in children with renal involvement (7.3 ng/ml) assessed by the DMSA scintigraphy compared to children without renal involvement (4.4 ng/ml, P = 0.010). The positive predictive value of suPAR seems high, since all patients without renal involvement had low suPAR values. During treatment the mean level of plasma suPAR decreased. Conclusion We conclude that plasma suPAR could be of clinical use for the diagnosis of acute pyelonephritis and that high levels of plasma suPAR might reflect the level of renal involvement and could therefore be a new indicator for renal scarring

Reliability of rubidium-82 PET/CT for renal perfusion determination in healthy subjects

Abstract Background Changes in renal perfusion may play a pathophysiological role in hypertension and kidney disease, however to date, no method for renal blood flow (RBF) determination in humans has been implemented in clinical practice. In a previous study, we demonstrated that estimation of renal perfusion based on a single positron emission tomography/computed tomography (PET/CT) scan with Rubidium-82 (82Rb) is feasible and found an approximate 5% intra-assay coefficient of variation for both kidneys, indicative of a precise method.This study’s aim was to determine the day-to day variation of 82Rb PET/CT and to test the method’s ability to detect increased RBF induced by infusion of amino acids. Methods Seventeen healthy subjects underwent three dynamic 82Rb PET/CT scans over two examination days comprising: Day A, a single 8-minute dynamic scan and Day B, two scans performed before (baseline) and after RBF stimulation by a 2-hour amino acid-infusion. The order of examination days was determined by randomization. Time activity curves for arterial and renal activity with a 1-tissue compartment model were used for flow estimation; the K1 kinetic parameter representing renal 82Rb clearance. Day-to-day variation was calculated based on the difference between the unstimulated K1 values on Day A and Day B and paired t-testing was performed to compare K1 values at baseline and after RBF stimulation on Day B. Results Day-to-day variation was observed to be 5.5% for the right kidney and 6.0% for the left kidney (n = 15 quality accepted scans). K1 values determined after amino acid-infusion were significantly higher than pre-infusion values (n = 17, p = 0.001). The mean percentage change in K1 from baseline was 13.2 ± 12.9% (range − 10.4 to 35.5) for the right kidney; 12.9 ± 13.2% (range − 15.7 to 35.3) for the left kidney. Conclusion Day-to-day variation is acceptably low. A significant K1 increase from baseline is detected after application of a known RBF stimulus, indicating that 82Rb PET/CT scanning can provide a precise method for evaluation of RBF and it is able to determine changes herein. Clinical Trial Registration EU Clinical Trials Register, 2017-005008-88. Registered 18/01/2018

Utility of a simplified [ 18 F] sodium fluoride PET imaging method to quantify bone metabolic flux for a wide range of clinical applications

We review the rationale, methodology, and clinical utility of quantitative [18F] sodium fluoride ([18F]NaF) positron emission tomography-computed tomography (PET-CT) imaging to measure bone metabolic flux (Ki, also known as bone plasma clearance), a measurement indicative of the local rate of bone formation at the chosen region of interest. We review the bone remodelling cycle and explain what aspects of bone remodelling are addressed by [18F]NaF PET-CT. We explain how the technique works, what measurements are involved, and what makes [18F]NaF PET-CT a useful tool for the study of bone remodelling. We discuss how these measurements can be simplified without loss of accuracy to make the technique more accessible. Finally, we briefly review some key clinical applications and discuss the potential for future developments. We hope that the simplified method described here will assist in promoting the wider use of the technique

Supplementary Material for: Bone Turnover, Mineralization, and Volume Estimated by 18F-Sodium Fluoride PET/CT and Biomarkers in Chronic Kidney Disease: Mineral and Bone Disorder Compared with Bone Biopsy

Introduction: Invasive bone biopsy to assess bone metabolism in patients with chronic kidney disease-mineral and bone disorder may be replaced by the noninvasive 18F-NaF PET/CT and biomarkers of bone metabolism. We aimed to compare parameters of bone turnover, mineralization, and volume assessed by bone biopsies with results derived from 18F-NaF PET/CT and biomarkers (bone-specific alkaline phosphatase, osteocalcin, fibroblast growth factor 23, and osteoprotegerin). Methods: A cross-sectional study included 17 dialysis patients, and results from 18F-NaF PET/CT scans and the biomarkers were directly compared with the results of histomorphometric analyses of tetracycline double-labeled trans-iliac bone biopsies. Results: Bone biopsies showed 40% high, 20% normal, and 40% low bone turnover. No biopsies had generalized abnormal mineralization, and the bone volume/total tissue volume was low in 80% and high in 7%. The pelvic skeletal plasma clearance (Ki) from 18F-NaF PET/CT correlated with bone turnover parameters obtained by bone biopsy (activation frequency: r = 0.82, p < 0.01; bone formation rate/bone surface: r = 0.81, p < 0.01), and Ki defined low turnover with high sensitivity (83%) and specificity (100%). CT-derived radiodensity correlated with bone volume, r = 0.82, p < 0.01. Of the biomarkers, only osteocalcin showed a correlation with turnover assessed by histomorphometry. Conclusion: In conclusion, 18F-NaF PET/CT may be applicable for noninvasive assessment of bone turnover and volume in CKD-MBD

Supplementary Material for: Bone Turnover, Mineralization, and Volume Estimated by 18F-Sodium Fluoride PET/CT and Biomarkers in Chronic Kidney Disease: Mineral and Bone Disorder Compared with Bone Biopsy

Introduction: Invasive bone biopsy to assess bone metabolism in patients with chronic kidney disease-mineral and bone disorder may be replaced by the noninvasive 18F-NaF PET/CT and biomarkers of bone metabolism. We aimed to compare parameters of bone turnover, mineralization, and volume assessed by bone biopsies with results derived from 18F-NaF PET/CT and biomarkers (bone-specific alkaline phosphatase, osteocalcin, fibroblast growth factor 23, and osteoprotegerin). Methods: A cross-sectional study included 17 dialysis patients, and results from 18F-NaF PET/CT scans and the biomarkers were directly compared with the results of histomorphometric analyses of tetracycline double-labeled trans-iliac bone biopsies. Results: Bone biopsies showed 40% high, 20% normal, and 40% low bone turnover. No biopsies had generalized abnormal mineralization, and the bone volume/total tissue volume was low in 80% and high in 7%. The pelvic skeletal plasma clearance (Ki) from 18F-NaF PET/CT correlated with bone turnover parameters obtained by bone biopsy (activation frequency: r = 0.82, p < 0.01; bone formation rate/bone surface: r = 0.81, p < 0.01), and Ki defined low turnover with high sensitivity (83%) and specificity (100%). CT-derived radiodensity correlated with bone volume, r = 0.82, p < 0.01. Of the biomarkers, only osteocalcin showed a correlation with turnover assessed by histomorphometry. Conclusion: In conclusion, 18F-NaF PET/CT may be applicable for noninvasive assessment of bone turnover and volume in CKD-MBD