Extramedullary hematopoiesis within paravertebral masses demonstrating prominent sestamibi and thallium uptake.

As a compensatory mechanism for bone marrow dysfunction, patients with severe anemia (of any etiology) may develop sites of extramedullary hematopoiesis (EMH). We present the case of a 67-year-old woman with thalassemia intermedia who underwent dual isotope myocardial perfusion imaging showing prominent sestamibi and thallium uptake within large paravertebral masses which were biopsy-proven to represent EMH. Although the precise mechanism of thallium or sestamibi uptake within sites of EMH is not documented, it might be speculated that the increased metabolic activity (and associated increased perfusion requirements) associated with vigorous hematopoiesis (medullary or extramedullary) in anemic states would result in increased deposition of perfusion imaging agents such as thallium or sestamibi. This case emphasizes the importance of careful inspection of raw images for extracardiac findings which may be of clinical relevance. In addition, this case highlights the potential utility of reconstructing the raw/cine SPECT imaging set into transaxial slices for direct correlation with other cross-sectional imaging modalities (eg, CT/MRI).