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BACKGROUND: Monitoring for acute allograft rejection improves outcomes after cardiac transplantation. Endomyocardial biopsy is the gold standard test defining rejection, but carries risk and has limitations. Cardiac magnetic resonance T2 mapping may be able to predict rejection in adults, but has not been studied in children. Our aim was to evaluate T2 mapping in identifying paediatric cardiac transplant patients with acute rejection. METHODS: Eleven paediatric transplant patients presenting 18 times were prospectively enrolled for non-contrast cardiac magnetic resonance at 1.5 T followed by endomyocardial biopsy. Imaging included volumetry, flow, and T2 mapping. Regions of interest were manually selected on the T2 maps using the middle-third technique in the left ventricular septal and lateral wall in a short-axis and four-chamber slice. Mean and maximum T2 values were compared with Students t-tests analysis. RESULTS: Five cases of acute rejection were identified in three patients, including two cases of grade 2R on biopsy and three cases of negative biopsy treated for clinical symptoms attributed to rejection (new arrhythmia, decreased exercise capacity). A monotonic trend between increasing T2 values and higher biopsy grades was observed: grade 0R T2 53.4 ± 3 ms, grade 1R T2 54.5 ms ± 3 ms, grade 2R T2 61.3 ± 1 ms. The five rejection cases had significantly higher mean T2 values compared to cases without rejection (58.3 ± 4 ms versus 53 ± 2 ms, p = 0.001). CONCLUSIONS: Cardiac magnetic resonance with quantitative T2 mapping may offer a non-invasive method for screening paediatric cardiac transplant patients for acute allograft rejection. More data are needed to understand the relationship between T2 and rejection in children.

Prostate specific membrane antigen (PSMA) directed PET imaging has rapidly transformed prostate cancer workup over the past decade and paved the way for a theranostic approach using 177Lu-labelled PSMA radioligand therapy (RLT). This review gives an overview of the underlying principles behind PSMA as a target; the current use of PSMA PET in prostate cancer imaging and benefits compared to conventional imaging; and therapeutic applications including optimisation of patient selection. It also explores the evidence base of PSMA PET for other indications not in routine clinical use and the future of PSMA-directed RLT. [ABSTRACT FROM AUTHOR]

Background: Although mortality has decreased considerably in pediatric heart transplantation, waitlist and post‐transplant death rates remain notable. End‐of‐life focused research in this population, however, is very limited. This Pediatric Heart Transplant Society study aimed to describe the circumstances surrounding death of pediatric heart transplant patients. Methods: A retrospective analysis of the multi‐institutional, international, Pediatric Heart Transplant Society registry was conducted. Descriptive statistics and univariate analyses were performed to 1) describe end‐of‐life in pediatric pre‐ and post‐heart transplant patients and 2) examine associations between location of death and technological interventions at end‐of‐life with demographic and disease factors. Results: Of 9217 patients (0–18 years) enrolled in the registry between 1993 and 2018, 2804 (30%) deaths occurred; 1310 while awaiting heart transplant and 1494 post‐heart transplant. The majority of waitlist deaths (89%) occurred in the hospital, primarily in ICU (74%) with most receiving mechanical ventilation (77%). Fewer post‐transplant deaths occurred in the hospital (22%). Out‐of‐hospital death was associated with older patient age (p <.01). Conclusions: ICU deaths with high use of technological interventions at end‐of‐life were common, particularly in patients awaiting heart transplant. In this high mortality population, findings raise challenging considerations for clinicians, families, and policy makers on how to balance quality of life amidst high risk for hospital‐based death. [ABSTRACT FROM AUTHOR]

The number of people living with dementia is increasing, but as yet there remains no cure or disease-modifying treatment. This review aims to help readers understand the role of 18F-FDG PET/CT imaging in the investigation of cognitive impairment and how the advent of amyloid PET/CT imaging may hold the key to radically changing management of the most common form of dementia - Alzheimer's disease. The indications for 18F-FDG PET/CT and amyloid PET/CT imaging in cognitive impairment are outlined. Additionally, the mechanisms of action, technique, patient preparation and acquisition parameters for both are detailed. We conclude by providing a framework for interpreting 18F-FDG PET/CT and amyloid PET/CT imaging in the more common conditions that lead to cognitive impairment conditions with tips on avoiding pitfalls in interpretation. [ABSTRACT FROM AUTHOR]

This study investigates the usefulness of quantitative SUVR thresholds on sub types of typical (type A) and atypical (non-type A) positive (Aβ+) and negative (Aβ-) 18F-florbetapir scans and aims to optimise the thresholds. Clinical 18F-florbetapir scans (n = 100) were categorised by sub type and visual reads were performed independently by three trained readers. Inter-reader agreement and reader-to-reference agreement were measured. Optimal SUVR thresholds were derived by ROC analysis and were compared with thresholds derived from a healthy control group and values from published literature. Sub type division of 18F-florbetapir PET scans improves accuracy and agreement of visual reads for type A: accuracy 90%, 96% and 70% and agreement κ > 0.7, κ ≥ 0.85 and −0.1 < κ < 0.9 for all data, type A and non-type A respectively. Sub type division also improves quantitative classification accuracy of type A: optimum mcSUVR thresholds were found to be 1.32, 1.18 and 1.48 with accuracy 86%, 92% and 76% for all data, type A and non-type A respectively. Aβ+/Aβ- mcSUVR threshold of 1.18 is suitable for classification of type A studies (sensitivity = 97%, specificity = 88%). Region-wise SUVR thresholds may improve classification accuracy in non-type A studies. Amyloid PET scans should be divided by sub type before quantification. We have derived and validated mcSUVR thresholds for Aβ+/Aβ- 18F-florbetapir studies. This work demonstrates that division into sub types improves reader accuracy and agreement and quantification accuracy in scans with typical presentation and highlights the atypical presentations not suited to global SUVR quantification. [ABSTRACT FROM AUTHOR]

There is a clinical need for 18 F-labeled somatostatin analogs for the imaging of neuroendocrine tumors (NET), given the limitations of using [ 68 Ga]Ga-DOTA-peptides, particularly with regard to widespread accessibility. We have shown that [ 18 F]fluoroethyl-triazole-[Tyr 3 ]-octreotate ([ 18 F]FET-βAG-TOCA) has favorable dosimetry and biodistribution. As a step toward clinical implementation, we conducted a prospective, noninferiority study of [ 18 F]FET-βAG-TOCA PET/CT compared with [ 68 Ga]Ga-DOTA- peptide PET/CT in patients with NET. Methods: Forty-five patients with histologically confirmed NET, grades 1 and 2, underwent PET/CT imaging with both [ 18 F]FET-βAG-TOCA and [ 68 Ga]Ga-peptide performed within a 6-mo window (median, 77 d; range, 6-180 d). Whole-body PET/CT was conducted 50 min after injection of 165 MBq of [ 18 F]FET-βAG-TOCA. Tracer uptake was evaluated by comparing SUV max and tumor-to-background ratios at both lesion and regional levels by 2 unblinded, experienced readers. A randomized, blinded reading of both scans was also then undertaken by 3 experienced readers, and consensus was assessed at a regional level. The ability of both tracers to visualize liver metastases was also assessed. Results: A total of 285 lesions were detected on both imaging modalities. An additional 13 tumor deposits were seen in 8 patients on [ 18 F]FET-βAG-TOCA PET/CT, and [ 68 Ga]Ga-DOTA-peptide PET/CT detected an additional 7 lesions in 5 patients. Excellent correlation in SUV max was observed between both tracers ( r = 0.91; P < 0.001). No difference was observed between median SUV max across regions, except in the liver, where the median tumor-to-background ratio of [ 18 F]FET-βAG-TOCA was significantly lower than that of [ 68 Ga]Ga-DOTA-peptide (2.5 ± 1.9 vs. 3.5 ± 2.3; P < 0.001). Conclusion: [ 18 F]FET-βAG-TOCA was not inferior to [ 68 Ga]Ga-DOTA-peptide in visualizing NET and may be considered in routine clinical practice given the longer half-life and availability of the cyclotron-produced fluorine radioisotope., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)