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Purpose: 4-18F-Fluoro-m-hydroxyphenethylguanidine (18F-4F-MHPG) and 3-18F-fluoro-p-hydroxyphenethylguanidine (18F-3F-PHPG) were developed for quantifying regional cardiac sympathetic nerve density using tracer kinetic analysis. The aim of this study was to evaluate their performance in cardiomyopathy patients. Methods: Eight cardiomyopathy patients were scanned with 18F-4F-MHPG and 18F-3F-PHPG. Also, regional resting perfusion was assessed with 13N-ammonia. 18F-4F-MHPG and 18F-3F-PHPG kinetics were analyzed using the Patlak graphical method to obtain Patlak slopes Kp (mL/min/g) as measures of regional nerve density. Patlak slope polar maps were used to evaluate the pattern and extent of cardiac denervation. For comparison, "retention index" (RI) values (mL blood/min/mL tissue) were also calculated and used to assess denervation. Perfusion polar maps were used to estimate the extent of hypoperfusion. Results: Patlak analysis of 18F-4F-MHPG and 18F-3F-PHPG kinetics was successful in all subjects, demonstrating the robustness of this approach in cardiomyopathy patients. Substantial regional denervation was observed in all subjects, ranging from 25 to 74% of the left ventricle. Denervation zones were equal to or larger than the size of corresponding areas of hypoperfusion. The two tracers provided comparable metrics of regional nerve density and the extent of left ventricular denervation. 18F-4F-MHPG exhibited faster liver clearance than 18F-3F-PHPG, reducing spillover from the liver into the inferior wall. 18F-4F-MHPG was also metabolized more consistently in plasma, which may allow application of population-averaged metabolite corrections. Conclusion: The advantages of 18F-4F-MHPG (more rapid liver clearance, more consistent metabolism in plasma) make it the better imaging agent to carry forward into future clinical studies in patients with cardiomyopathy. Trial registration: Registered at the ClinicalTrials.gov website (NCT02669563). URL:https://clinicaltrials.gov/ct2/show/NCT02669563 [ABSTRACT FROM AUTHOR]

Twenty-nine patients genetically at risk for Huntington's Disease and 64 volunteer controls underwent positron emission tomography (PET) scanning of ″FDG metabolism. These persons were also evaluated for anxiety immediately before and after the PET-Scan procedure with the State-Trait Anxiety Inventory (STAI). The State anxiety measures for the at-risk patients were significantly higher than were those for the volunteers both before and after the scan, although the effect was no longer significant when age was included as a covariate. For both groups, subjects having higher Trait anxiety scores also had significantly higher State anxiety measures. Females were significantly higher than males on State anxiety, although this effect may be derived from less of a willingness on the part of males to report emotional apprehension or fear. Furthermore, subjects' State anxiety decreased significantly once the PET procedure was finished. Individual differences on factors such as those noted above should be considered in attempts to inform and prepare patients for medical diagnostic procedures, such as PET. This can lead to a more positive experience for the patient in the medical diagnostic setting, and physiologically-based measures from such tests that are less confounded by the concomitants of heightened emotional arousal. [ABSTRACT FROM PUBLISHER]

Background: Disease-induced damage to cardiac autonomic nerve populations is associated with an increased risk of sudden cardiac death. The extent of cardiac sympathetic denervation, assessed using planar scintigraphy or positron emission tomography, has been shown to predict the risk of arrhythmic events in heart failure patients staged for implantable cardioverter defibrillator therapy. The goal of this study was to perform first-in-human evaluations of 4-[ 18 F]fluoro-meta-hydroxyphenethylguanidine and 3-[ 18 F]fluoro-para-hydroxyphenethylguanidine, 2 new positron emission tomography radiotracers developed for quantifying regional cardiac sympathetic nerve density., Methods and Results: Cardiac positron emission tomography studies with 4-[ 18 F]fluoro-meta-hydroxyphenethylguanidine and 3-[ 18 F]fluoro-para-hydroxyphenethylguanidine were performed in normal subjects (n=4 each) to assess their imaging properties and organ kinetics. Patlak graphical analysis of their myocardial kinetics was evaluated as a technique for generating nerve density metrics. Whole-body biodistribution studies (n=4 each) were acquired and used to calculate human radiation dosimetry estimates. Patlak analysis proved to be an effective approach for quantifying regional nerve density. Using 960 left ventricular volumes of interest, across-subject Patlak slopes averaged 0.107±0.010 mL/min per gram for 4-[ 18 F]fluoro-meta-hydroxyphenethylguanidine and 0.116±0.010 mL/min per gram for 3-[ 18 F]fluoro-para-hydroxyphenethylguanidine. Tracer uptake was highest in heart, liver, kidneys, and salivary glands. Urinary excretion was the main elimination pathway., Conclusions: 4-[ 18 F]fluoro-meta-hydroxyphenethylguanidine and 3-[ 18 F]fluoro-para-hydroxyphenethylguanidine each produce high-quality positron emission tomography images of the distribution of sympathetic nerves in human heart. Patlak analysis provides reproducible measurements of regional cardiac sympathetic nerve density at high spatial resolution. Further studies of these tracers in heart failure patients will be performed to identify the best agent for clinical development., Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT02385877.