Questions & Answers Could you please explain slide 19 - false negatives and positives, how they would affect the reading? And why would they be mistaken? Sure, in Bone scan the radioactive material will be localized in the osteoblastic sites in the body. In slide 19 we're specifically talking about the pattern of the MSK Tumor( this is a key) because if there is a tumor in the body, it will have high activity in the Bone scan. However, if the patient has osteoarthritis, multifocal infection, or multiple trauma the lesions that affected will have also increase uptake. So, if both have the same appearances it might be mistaken in reading, and this is a false positive. In False negative, the lesion will appear photopenic ( no uptake). For example, if a patient has low bone turnover and has a tumor, we might not see the tumor because the patient has another disease that affects the physiology of the bone and leads to affect the Bone scan (because we are imaging the physiological process in Bone scan)