Superior Vena Cava Syndrome Induced Collateral Circulation on 99mTc-Macroaggregated Albumin Lung Perfusion Scintigraphy.

Perfusion lung scintigraphy using SPECT/CT is one mainstay in diagnosing pulmonary embolism. Although typically almost all tracer will be accumulated in the lung capillaries, occasionally abnormal uptake can be detected. As superior vena cava syndrome leads to aberrant blood flow, tracer injected to an arm vein might partly circumvent the pulmonary capillary bed and accumulate in well-perfused anatomical structures. In this case, next to the commonly described liver enhancement, more prominent pseudo-uptake of various thoracic vertebrae was observable. However, a time-related FDG PET/CT demonstrated only the hepatic pseudo-uptake. Taken together, careful assessment of superior vena cava syndrome patient studies is highly recommended.