Extraosseous accumulation of bone scan tracer 99mTc-methylene diphosphonate in a phlebolith
A 43-year-old female patient, known case of adenocarcinoma of right lung was referred for a 99mTc-MDP bone scan with complaint of persistent low backache since 3 months. A whole body 99mTc-MDP bone scan was performed. The scan showed abnormal, focal increased tracer uptake in left pelvic cavity, not localizing to any bone of the skeleton [Figures and , arrows]. All the bones of the axial and appendicular skeleton showed normal tracer uptake. The uptake was persistent even in post-void imaging done after adequate hydration, giving us a clue that it was not due to tracer hold up in the ureter. On single photon emission computed tomography and computed tomography (SPECT-CT) imaging, the focal tracer uptake localized to a small focus of calcification in the left pelvic cavity away from the ureter [, arrow]. An additional ultrasonography of the pelvis confirmed that there was no ureteric calculus []. Review of the patient's recent contrast-enhanced computed tomography revealed a phlebolith in left iliac vein (CT Hounsfield unit: 338). Thus, we concluded the extraosseous 99mTc-MDP uptake was due to phlebolith in the left iliac vein.