Vasovagal-related stress immediately before FDG injection may increase bilateral adrenal FDG uptake

Abstract

This study was partly presented at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2014 and the same set of data has already been published in J Nucl Med 2014; 55 (supplement 1): 1928 in abstract form.Objective: To evaluate the relationship between vasovagalrelated stress on positron emission tomography (PET)/CT and adrenal fludeoxyglucose (FDG) uptake. Methods: We reviewed the medical records of 1358 consecutive patients who underwent FDG PET/CT examinations and selected those who presented with vasovagalrelated symptoms and acute hypotension immediately before FDG injection (vasovagal reflex group). Patients who underwent FDG PET/CT examinations on the same days as the vasovagal reflex group without new complaints or any adrenal lesion were used as controls. We evaluated adrenal FDG uptake visually and by means of adrenal maximum standardized uptake value (SUV max ) and adrenal/ liver (A/L) SUV max ratio. Next, we reviewed the FDG PET/CT images of the same 1358 patients and selected the cases presenting with bilateral avid FDG uptake.Results: 4 patients were included in the vasovagal reflex group, and all of them showed bilateral avid adrenal FDG uptake visually, while 19 patients in the control group did not. The mean adrenal SUV max and the mean A/L SUV max ratio were significantly higher in the vasovagal reflex group than in the control group (p , 0.001). 10 (0.74%) patients, including 4 patients from the vasovagal reflex group, showed bilateral avid FDG uptake with normal adrenal configuration on CT. Conclusion: Vasovagal-related stress immediately before FDG injection may increase bilateral adrenal FDG uptake. Advances in knowledge: Vasovagal-related stress may be included in the differential diagnosis of the cause of bilateral avid adrenal FDG uptake. INTRODUCTIONPrevious studies have reported the utility of fludeoxyglucose (FDG) positron emission tomography (PET)/CT to characterize adrenal diseases, especially to distinguish benign from malignant adrenal disease. 1-3 FDG uptake is usually higher in malignant adrenal tumours than in benign adrenal tumours, but some adenomas are also known to show avid FDG uptake. 2,3 We encountered a female patient who presented with pallor and hypotension immediately before FDG injection and bilateral avid adrenal FDG uptake despite normal adrenal configuration on CT. We speculated that the avid uptake may be due to adrenal activation caused by vasovagal-related stress. However, vasovagal-related stress-induced adrenal avid FDG uptake has never been reported as a full article.The purpose of this study was to examine whether adrenal FDG uptake increases under vasovagal-related stress conditions. First, we compared the adrenal FDG uptake between patients with vasovagal-related symptoms immediately before FDG injection and those without such symptoms. Next, we examined the frequency of bilateral avid adrenal FDG uptake with normal adrenal CT configuration on FDG PET/CT examinations. METHODS AND MATERIALSOur institutional review board approved this retrospecti...

FDG–PET findings associated with various medical procedures and treatments

“…Plasma epinephrine levels increase immediately before vasovagal reflex onset. Therefore, vasovagal-related stress just before FDG injection is considered one of the causes of increased uptake in the bilateral adrenal glands with normal adrenal configuration [ 81 ] (Fig. 17 ).…”