Table 4. Definitions of grading systems for the extent of skeletal disease in prostate cancer using a bone scan.

Reference	Method	Description
Soloway et al (1988)	Visual inspection	The total number of bone lesions were counted visually and graded into five categories: 0, normal; 1, less than six lesions; 2, 6–20 lesions; 3, more than 20 lesions but not a superscan; 4, superscan.
Amico et al (1991)	Visual inspection	A bone scan scoring system from 0 to 2, 0 represents normal uptake, 1 means one or several uptakes and 2 signifies diffuse uptake.
Chybowski et al (1991)	Visual inspection	A simple bone scan scoring system was similer to the above. This clasification was negative, positive or indeterminate.
Dann et al (1987)	Measurements of the total radiotracer uptake	The 24-h whole body retention was measured as an objective marker for bone metastasis.
Sabbatini et al (1999)	Visual inspection	A BSI was based on the known proportional weights of each of the 158 bones that were derived from the reference man.
Erdi et al (1997)	Computer analysis	The images were transferred to a computer for ROI analysis and the BSI was calculated.
Present study	Visual and computer analysis	The %PABS was quantified automatically using a computer with the NIH Image.