Potential use of Rubidium-82 PET to differentiate neoplasms from inflammatory lesion: Case report
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Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore
Received Sep 1, 2020; accepted Sep 4, 2020 doi:10.1007/s12350-020-02394-9
INTRODUCTION Rubidium-82 (Rb-82) and Thallium-201 (Tl-201) have similar activity to that of a potassium ion (K?). Both tracers are active participants in the sodium– potassium exchange pump of cells. They are rapidly extracted from the blood and are taken up by the cells in relation to the tissue perfusion, which requires energy for cells uptake through Na?/K?-ATPase. This characteristic makes these tracers the gold standard in studying myocardial perfusion. As with Tl-201, Rb-82 has been reported in literature to have increased uptake in both benign and malignant neoplasms which were incidentally noted on Rb-82 PET myocardial perfusion studies. Increased Rb82 accumulation was reported in Spironolactone-induced gynecomastia,1 metastases from pheochromocytoma2 and metastatic breast cancer to the brain. Tl-201 has approved use in brain SPECT imaging to distinguish CNS lymphoma from toxoplasmosis in AIDS patients. There are no reports in the literature which describe the potential use of Rb-82 to differentiate inflammatory/infectious from neoplastic lesions. We present two case reports of pathologyproven neoplastic and inflammatory lesions incidentally noted on Rb-82 FDG PET myocardial perfusion-viability imaging studies with different Rb-82 and 18-F FDG activity.
Reprint requests: Samar Hajj, MD, Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore; [email protected] J Nucl Cardiol 1071-3581/$34.00 Copyright Ó 2020 American Society of Nuclear Cardiology.
CASE PRESENTATION Case 1 An 83-year-old man with history of Diabetes Mellitus type 2, intermittent atrial fibrillation, hyperlipidemia and peripheral vascular disease, presents to his primary care physician for the workup of paroxysmal VTach. A Rb-82 PET myocardial perfusion at rest and viability test was performed to exclude active inflammatory cardiac lesion such as sarcoidosis. The PET myocardial perfusion images demonstrate normal perfusion to the left ventricle. However, there was an incidental finding of a speculated lung mass seen in the superior segment of the right lower lobe. This mass demonstrates increased Rb-82 accumulation (SUV max = 30.2; blood pool SUV = 17.0) and mildly increased FDG uptake on the FDG metabolic study (SUV max = 2.0) (Figure 1). Case 2 A 61-year-old man with known history of sarcoidosis and complete heart block s/p pacemaker placement, atrial flutter status post ablation and sleep apnea, had a Rb-82 FDG PET myocardial study for evaluation of cardiac sarcoidosis. The Rest Rubidium-FDG PET/CT imaging study showed no evidence of cardiac sarcoidosis. However, there were hypermetabolic enlarged mediastinal and hilar nodes on FDG PET (SUV max = 10.2; blood pool SUV = 2.8) showing no increased activity on the rest Rb-82 imaging (SUV max = 13.0; blood pool SUV = 13.0) (Figure 2).
Hajj et al Potential use of Rubidium-82 PET to diffe
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