Unexpected extracardiac findings during Rubidum-82 (Rb-82) myocardial positron emission tomography (PET) perfusion imaging: Three years of experience

Objectives Rb-82 myocardial perfusion PET is increasingly utilized for detection of coronary artery disease. A variety of abnormalities, however, can be detected that show either direct radiotracer uptake on emission data or other abnormality on transmission data. We report 4 patients with unexpected extracardiac abnormalities during Rb-82 myocardial perfusion PET.

Methods We investigated approximately 3700 patients during December 2006-December 2009. All patients were referred for the evaluation of coronary artery disease and underwent Rb-82 myocardial perfusion PET study with pharmacological stress. Studies were performed in a high-resolution Siemens/ECAT ACCEL-LSO crystal PET scanner. Transmission images were acquired to confirm proper patient positioning and attenuation correction utilizing the scanner germanium-68 source. Patients were stressed pharmacologically and 40-60 mCi of Rb-82 were infused for rest and stress studies and ECG-gated emission images were acquired. Transaxial images were reconstructed with OSEM 3 - D algorithm and displayed in the format of 3 mm thick slices.

Results Extracardiac findings were identified in 17 of the 3700 patients. Four patients subsequently underwent follow-up with confirmation of pathology. One patient underwent resection for pulmonary carcinoid (n=1), one for breast carcinoma (n=1), and two for pulmonary adenocarcinoma (n=2). Incidentally, multiple patients with evidence of a previous mastectomy were also found but were not counted in the abnormal patient population due to lack of follow-up.

Conclusions During Rb-82 myocardial PET perfusion tests performed for the evaluation of suspected coronary artery disease, readers must be attentive to the possibility of unexpected extracardiac findings. A large variety of findings can be detected on Rb-82 myocardial PET perfusion including morphological changes and malignancy