18F-FDG PET/CT in the Diagnostic Workup of Infective Endocarditis and Related Intracardiac Prosthetic Material: A Clear Message.

Abstract

1669 Objectives Myocardial Perfusion Scan (MPS) has been frequently used for the evaluation of the coronary artery diseases and prediction of cardiac events. MPS has also been used for the preoperative medical clearance in patients with multiple medical comorbidities. Authors evaluated the incidences of non-visualization of the gallbladder (GB) on either or both stress and rest MPS and its clinical significance. Methods Among 473 MPS patients between May and Oct. 31, 2015, 447 patients (239 men and 208 women; 30 to 93 years old; avg 67.7) were evaluated after excluding 12 patients with “2” days protocols and 14 patients with GB fossa not properly included on either stress or rest MPS. “1” day rest and stress protocol includes the intravenous administration of 8-12 mCi (296-444 Mbq) of Tc-99m MIBI for the rest MPS and 24-35 mCi (888-1295 Mbq) for the stress MPS. Stress MPS is typically acquired 2-5 hours from the initial rest dose injection, so that compatible to 2-5 hours delayed images of the hepatobiliary scan. Results GB were seen on both rest and stress MPS in 401 patients (Gp 1) while seen only on stress MPS in 18 patients (Gp 2) and not seen on both stress and rest MPS in 28 patients (Gp 3). 8 patients of Gp and 23 patients of Gp 3 had previous US or CT scan. 5 of 8 Gp patients with US or CT scan showed gallstones and/or wall thickening. In 23 Gp 3 patients with US or CT scan, 14 patients had cholecystectomy and 4 patients showed gallstones, wall thickening and/or pericholecystic fluid. Conclusions Typical MPS includes the areas from the lower neck to the upper abdomen, so that could evaluate both intracardiac and extracardiac abnormalities within the field. Incidental discovery of extracardiac lesions, particularly breast and lung cancer, has been reported frequently on MPS. GB is an additional organ which could readily be evaluated on MPS. In 23 of 31 (74.2%) Gp and Gp 3 patients, various GB abnormalities were confirmed by US or CT. Acute cholecystitis was ruled out in 2 Gp patients by preoperative MPS in spite of high US and clinical suspicion while acute cholecystitis was confirmed by additional hepatobiliary scan and surgery in 1 Gp 3 patient whose US and clinical suspicion were low. Valuable information regarding the GB could be obtained from the MPS without any additional radiation to both patients and technologists, imaging time or cost.