About BSI

The Bone Scan Index

• represents the percentage of total skeletal mass taken up by the tumors [1]
• is a valuable metric for estimating metastatic burden in patients with advanced prostate cancer [1]
  
• is a reproducible, quantitative expression of tumor burden seen on bone [2]
• is suggested as a prognostic tool in advanced prostate cancer; for stratifying prostate cancer patients entering treatment protocols for the extent of the tumor involvement of bone; and for the development of a disease progression or treatment response biomarker in prostate cancer

Background

• Whole-body bone scintigraphy is the most widely available and least expensive technique for the detection of bone metastases in patients with prostate cancer
  
• There is no standard established for evaluating and interpreting whole-body bone scintigraphy
  

Estimating BSI

• The estimation of BSI is based on the known proportional weights of each of the 158 bones that were derived from the reference man, a standardized skeleton in which autopsy-based individual bone weights were reported for the average adult [3]
  
• BSI is calculated by summing the fractional contribution of each bone expressed as a percentage of the entire skeleton (see Figure 1) [4]
  
• A BSI value of 1.0 indicates the tumor(s) to be present in 1% of the entire skeleton (arms and legs included) 
  
• Automated quantification of BSI based on the original method developed by Memorial Sloan-Kettering Cancer Center, New York, USA, is available.