Increased MIBG activity in the uterine cervix due to menstruation.

A 21-year-old woman with history of presacral ganglioneuroblastoma underwent I-MIBG scan for restaging. Planar images revealed increased MIBG activity in the upper pelvis, suggestive of disease recurrence. Complementary SPECT/CT images, however, localized the activity to the uterine cervix. Upon further questioning, it has been established that the patient was menstruating. Subsequent follow-up scans proved normal, confirming the benign etiology of these findings. The case shows that radioactive blood accumulation in the uterine cervix can interfere with MIBG scan interpretation in menstruating patients.