Unexpected 99mTc-tetrofosmin findings during myocardial perfusion scintigraphy: intraindividual comparison with...

99mTc-tetrofosmin single photon emission computed tomography (SPECT) is routinely used in the evaluation of coronary artery disease. A variety of different tumors, however, also demonstrate 99mTc-tetrofosmin uptake. We report six patients found with unexpected mediastinal and thoracic tumor uptake during Tc-tetrofosmin myocardial perfusion scintigraphy (MPS).

We investigated 2,155 patients with Tc-tetrofosmin MPS during 2006-2007. One thousand four hundred and eighty-six of these patients had no coronary history and were sent to our department due to newly developed thoracic complaint such as chest pain, dyspnea and others. Six hundred and sixty-nine patients had coronary history. All patients underwent 99mTc-tetrofosmin exercise study. Patients with unexpected extracardiac Tc-tetrofosmin findings during MPS were referred to PET/CT for further diagnostic investigation. Region of interest (ROI; 99mTc-tetrofosmin) and SUVmax (2-[F]fluoro-2-deoxy-D-glucose, F-FDG) were estimated and the results were compared with histological findings.

Abnormal mediastinal and/or thoracic activities were visualized in six of the 2,155 patients with 99mTc-tetrofosmin images. Subsequently, the patients underwent resection of a thymoma (n=2), nonsmall cell lung cancer (n=1) and breast cancer (n=3). In the patients with breast cancer one was a male patient with ductal, invasive breast cancer. Benign thymomas showed high 99mTc-tetrofosmin ROI >4.0 and low F-FDG SUVmax <2.0, whereas low 99mTc-tetrofosmin ROI <2.0 were found in nonsmall cell lung cancer and breast cancer and high F-FDG SUVmax >2.5 in these malignant tumors.

During Tc-tetrofosmin SPECT exercise stress tests performed in patients with suspected coronary artery disease, much more attention must be given to unexpected extracardiac uptakes. With 99mTc-tetrofosmin a large variety of different unknown tumors can be detected during MPS.