Cardiac fludeoxyglucose-18 positron emission tomography in genotype-positive arrhythmogenic cardiomyopathy.

BACKGROUND: Myocardial inflammation contributes to the pathogenesis of arrhythmogenic cardiomyopathy (ACM), a clinically and genetically heterogenous disorder. Due to phenotypic overlap, some patients with genetic ACM may be evaluated for an underlying inflammatory cardiomyopathy. However, the cardiac fludeoxyglucose (FDG) positron emission tomography (PET) findings in ACM patients have not been elucidated. METHODS: All genotype-positive patients in the Mayo Clinic ACM registry (n = 323) who received a cardiac FDG PET were included in this study. Pertinent data were extracted from the medical record. RESULTS: Collectively, 12/323 (4%; 67% female) genotype-positive ACM patients received a cardiac PET FDG scan as part of their clinical evaluation (median age at scan 49 ± 13 years). Amongst these patients, pathogenic/likely pathogenic variants were detected in LMNA (n = 7), DSP (n = 3), FLNC (n = 1) and PLN (n = 1). Of note, 6/12 (50%) had abnormal myocardial FDG uptake, including diffuse (entire myocardium) uptake in 2/6 (33%), focal (1-2 segments) uptake in 2/6 (33%) and patchy (3+ segments) in 2/6 (33%). Median myocardial standardized uptake value ratio was 2.1. Interestingly, LMNA-positive patients accounted for 3 out of 6 (50%) positive studies (diffuse uptake in 2 and focal uptake in 1). CONCLUSION: Abnormal myocardial FDG uptake is common in genetic ACM patients undergoing cardiac FDG PET. This study further supports the role of myocardial inflammation in ACM. Further investigation is needed to determine role of FDG PET in diagnosis and management of ACM and investigate the role of inflammation in ACM.

Bayesian penalized likelihood PET reconstruction impact on quantitative metrics in diffuse large B-cell lymphoma.

Evaluate the quantitative, subjective (Deauville score [DS]) and reader agreement differences between standard ordered subset expectation maximization (OSEM) and Bayesian penalized likelihood (BPL) positron emission tomography (PET) reconstruction methods. A retrospective review of 104 F-18 fluorodeoxyglucose PET/computed tomography (CT) exams among 52 patients with diffuse large B-cell lymphoma. An unblinded radiologist moderator reviewed both BPL and OSEM PET/CT exams. Four blinded radiologists then reviewed the annotated cases to provide a visual DS for each annotated lesion. Significant (P < .001) differences in BPL and OSEM PET methods were identified with greater standard uptake value (SUV) maximum and SUV mean for BPL. The DS was altered in 25% of cases when BPL and OSEM were reviewed by the same radiologist. Interobserver DS agreement was higher for OSEM (>1 cm lesion = 0.89 and ≤1 cm lesion = 0.84) compared to BPL (>1 cm lesion = 0.85 and ≤1 cm lesion = 0.81). Among the 4 readers, average intraobserver visual DS agreement between OSEM and BPL was 0.67 for lesions >1cm and 0.4 for lesions ≤1 cm. F-18 Fluorodeoxyglucose PET/CT of diffuse large B-cell lymphoma reconstructed with BPL has higher SUV values, altered DSs and reader agreement when compared to OSEM. This report finds volumetric PET measurements such as metabolic tumor volume to be similar between BPL and OSEM PET reconstructions. Efforts such as adoption of European Association Research Ltd accreditation should be made to harmonize PET data with an aim at balancing the need for harmonization and sensitivity for lesion detection.

99mTc-Tilmanocept Versus 99mTc-Sulfur Colloid in Lymphoscintigraphy: Sentinel Lymph Node Identification and Patient-Reported Pain.

Lymphoscintigraphy plays a vital role in sentinel lymph node (SLN) identification in oncologic breast surgery. The effectiveness of SLN localization and the degree of patient pain were compared between filtered 99mTc-sulfur colloid (99mTc-SC) and 99mTc-tilmanocept. Methods: A retrospective review of patients undergoing lymphoscintigraphy for breast cancer using 99mTc-SC (June 1, 2010, to December 31, 2011) or 99mTc-tilmanocept (June 1, 2013, to January 31, 2014) was performed. SLN appearance time and uptake, SLN pathology, proportion of positive SLNs removed, and pain scores were compared for each radiopharmaceutical using the χ2 test, Fisher exact test, and unequal variance t test, as appropriate. Results: In total, 76 patients, with 86 evaluated axillae, underwent lymphoscintigraphy: 29 with 99mTc-SC and 47 with 99mTc-tilmanocept. The mean SLN appearance time was 11.0 min for 99mTc-SC and 19.3 min for 99mTc-tilmanocept (P = 0.003). There was no difference in the mean transit uptake percentage: 2.2% for 99mTc-SC and 1.9% for 99mTc-tilmanocept (P = 0.55). 99mTc-tilmanocept identified a greater proportion of intraoperative blue nodes than did 99mTc-SC (P = 0.03). There was no significant difference between 99mTc-SC and 99mTc-tilmanocept in the number of SLNs removed, number of patients with positive SLNs, or pain score. Conclusion: 99mTc-SC use in lymphoscintigraphy is an acceptable alternative to 99mTc-tilmanocept for SLN detection in breast cancer, on the basis of the similarity in intraoperative SLN identification and pain scores.