If the bone scan is inconclusive- What to do?

My uncle who has prostate cancer  had a bone scan that was not conclusive and could not tell us clearly  whether he has metastatic disease in his bones or not.  Are there any other imaging tests that can help us determine  if he has cancer in his bones?   Is it really important to have an earlier, more accurate diagnosis of any bone disease or are we just overly anxious about the possibility of progression of PC into the bone?

Review Article: Diagnosis of Bone Metastases in Urological Malignancies- An Update.

Nathan Lawrentschuk et al.

Urology 76:782-790, 2010