Musculoskeletal CT Scans

Question: My father/s latest bone scintigraphy was read by a doctor who is a radiology resident. My father has advanced prostate cancer and bone scintigraphy from Sep. 2011 showed 2 hot-spots on his right upper pelvic branch and VL5. Apr. 2014: the results read that 2 spots in pelvis and VL5 were smaller compared to the previous bone scintigram, and that there is a new larger spot on his sacrum. My father says that the doctor asked several times if he emptied his bladder, and my father said he did twice before the scan. Then the doctor asked him after the first scan to try to pee once more, and my father said he couldn’t. So they repeated the scan, this time him laying on his side (?). My question: is it possible that the residual urine in the bladder gave a positive signal, and that it was mistakenly read as a hot-spot on his sacrum? From my understanding, the sacrum is exactly behind the bladder. Many thanks, best to you.

Answer: Thank you for contacting the Bone and Joint Ask an Imaging expert forum. Our experts would like to reassure you that a faculty member oversees every scan, and that each scan is reviewed by the faculty member before the final interpretation is submitted. Your knowledge of pelvic anatomy is correct in saying that the sacrum is right behind the bladder. The lateral (side-lying) view would separate the bladder from the sacrum so it is easier to detect a sacral lesion. A full bladder can hide the sacrum and cause lesions to be missed, but activity in the bladder will not be mistaken for a bone lesion. Your father’s oncologist may order another type of imaging if he/she feels that this lesion should be confirmed. If so, we recommend scheduling this imaging at one of our Memorial Hermann Imaging Centers by calling 713-512-6040 for Memorial Hermann appointments, or 713-526-4243 for LBJ hospital appointments.