Quantification of 18F-fluoride kinetics: evaluation of simplified methods

18F-fluoride PET is a promising noninvasive method for measuring bone metabolism and bone blood flow. The purpose of this study was to assess the performance of various clinically useful simplified methods by comparing them with full kinetic analysis. In addition, the validity of deriving bone blood flow from K1 of 18F-fluoride was investigated using 15O-H2O as a reference. Methods: Twenty-two adults (mean age ± SD, 44.8 ± 25.2 y), including 16 patients scheduled for bone surgery and 6 healthy volunteers, were studied. All patients underwent dynamic 15O-H2O and 18F-fluoride scans before surgery. Ten of these patients had serial PET measurements before and at 2 time points after local bone surgery. During all PET scans, arterial blood was monitored continuously. 18F-fluoride data were analyzed using nonlinear regression (NLR) and several simplified methods (Patlak and standardized uptake value [SUV]). SUV was evaluated for different time intervals after injection and after normalizing to body weight, lean body mass, and body surface area, and simplified measurements were compared with NLR results. In addition, changes in SUV and Patlak-derived fluoride influx rate (Ki) after surgery were compared with corresponding changes in NLR-derived Ki. Finally, 18F-fluoride K1 was compared with bone blood flow derived from 15O-H2O data, using the standard single-tissue-compartment model. Results: K1 of 18F-fluoride correlated with measured blood flow, but the correlation coefficient was relatively low (r = 0.35, P < 0.001). NLR resulted in a mean Ki of 0.0160 ± 0.0122, whereas Patlak analysis, for the interval 10-60 min after injection, resulted in an almost-identical mean Ki of 0.0161 ± 0.0117. The Patlak-derived Ki, for 10-60 min after injection, showed a high correlation with the NLR-derived Ki (r = 0.976). The highest correlation between Ki and lean body mass-normalized SUV was found for the interval 50-60 min (r = 0.958). Finally, changes in SUV correlated significantly with those in Ki (r = 0.97). Conclusion: The present data support the use of both Patlak and SUV for assessing fluoride kinetics in humans. However, 18F-fluoride PET has only limited accuracy in monitoring bone blood flow

Usefulness of Left Atrial Emptying Fraction to Predict Ventricular Arrhythmias in Patients With Implantable Cardioverter Defibrillators

Contains fulltext : 176957.pdf (Publisher’s version ) (Open Access)Impaired left atrial emptying fraction (LAEF) is an important predictor of mortality in patients with heart failure. As it may reflect increased LV wall stress, it might predict ventricular arrhythmia (VA) specifically. This study evaluated the predictive value of LAEF assessed with cardiovascular magnetic resonance (CMR) imaging with respect to appropriate device therapy (ADT) for VA and compared its role with CMR assessed scar size and other risk factors. In total, 229 patients (68% male, 63 +/- 10 years, 61% ischemic cardiomyopathy) with LV ejection fraction median and scar size median experienced 40% ADT at 5 years (log-rank p = 0.01). In conclusion, LAEF independently predicts ADT in patients with primary prevention ICDs. Combined assessment of LAEF and scar size identifies a group with low risk of ADT. Therefore, LAEF assessment could assist in risk stratification for VA to select patients with the highest benefit from ICD implantation

Implantable defibrillator therapy and mortality in patients with non-ischaemic dilated cardiomyopathy An updated meta-analysis and effect on Dutch clinical practice by the Task Force of the Dutch Society of Cardiology

Background Primary prophylactic implantable cardioverter-defibrillators (ICDs) in patients with non-ischaemic cardiomyopathy (NICMP) remains controversial. This study sought to assess the benefit of ICD therapy with or without cardiac resynchronisation therapy (CRT) in patients with NICMP. In addition, data were compared with real-world clinical data to perform a risk/benefit analysis. Methods Relevant randomised clinical trials (RCTs) published in meta-analyses since DANISH, and in PubMed, EMBASE and Cochrane databases from 2016 to 2020 were identified. The benefit of ICD therapy stratified by CRT use was assessed using random effects meta-analysis techniques. Results Six RCTs were included in the meta-analysis. Among patients without CRT, ICD use was associated with a 24% reduction in mortality (hazard ratio [HR]: 0.76; 95% confidence interval [CI]: 0.62-0.93; P = 0.008). In contrast, among patients with CRT, a CRT-defibrillator was not associated with reduced mortality (HR: 0.74, 95% CI 0.47-1.16; P = 0.19). For ICD therapy without CRT, absolute risk reduction at 3-years follow-up was 3.7% yielding a number needed to treat of 27. Conclusion ICD use significantly improved survival among patients with NICMP who are not eligible for CRT. Considering CRT, the addition of defibrillator therapy was not significantly associated with mortality benefit compared with CRT pacemaker