Tc-99m Tetrofosmin SPECT-CT as a Guide to Core Needle Biopsy of a Giant Thymoma

Extracardiac images are occasionally revealed on Tc-99m tetrofosmin single photon emission computed tomography-computed tomography (SPECT-CT) imaging due to the known oncotropic properties of the tracer. A large area of inhomogeneous tracer uptake was revealed on SPECT-myocardial perfusion imaging in a 59-year-old male patient referred to our department for suspected coronary artery disease. On subsequent SPECT-CT, the mass was located in the anterior mediastinum, characterized by regular margins not infiltrating the adjacent anatomical structures, and had diameters of 6 cm × 5.2 cm × 10.3 cm. A very high uptake ratio value, equal to 26, strengthened the suspicion of giant thymoma. However, an ultrasound (US)-guided transcutaneous core biopsy was deemed necessary before surgical removal of the lesion due to its extremely large size and the absence of associated paraneoplastic syndromes. In this aspect, the SPECT-CT imaging proved to be very useful in guiding the sampling procedure in an area rich in viable cells, due to the presence of multiple areas of necrosis of various sizes that could have affected the outcome of the US-guided core biopsy.