Comparison of quantitative and visual detection of new focal bone lesions.

A comparison is made between the sensitivity of detection of focal abnormalities in radionuclide bone images by visual examination and by using simple quantification. The quantitative method calculates the ratio of radiopharmaceutical uptake in a region of interest drawn around a lesion to that in an area of normal bone. Quantification is found to be far more sensitive than visual examination in detecting focal metastases. The use of "baseline" images improved the precision of quantitation of rib lesions, but appeared not to alter the sensitivity of visual detection. This method of quantification is therefore limited more by the inability of observers to notice suspicious areas to which it should be applied than by inaccuracies inherent in the method itself. Further work should concentrate more on image enhancement than on improving quantitative techniques.