24 hour/3 hour radio-uptake technique for differentiating degenerative and malignant bony lesions in bone scanning.

Differentiating bony metastases from degenerative lesions is of great importance to the oncologist. Routine bone scanning using technetium-99m methylene diphosphonate is the investigation of choice for detecting bony lesions, but its specificity is low. Using the difference in radio-uptake behaviour of metastatic and degenerative lesions as the criterion, a 24/3 h radio-uptake, lesion to non-lesion ratio was used to separate out the two types of lesions. Radio-uptake ratio (RUR) distribution curves of malignant and degenerative lesions were found to be significantly different (P < 0.001). Taking 1.12 as the critical point, RUR of malignant lesions was found to be more than the critical point, and that of degenerative lesions was found to be less than the critical point. Sensitivity, specificity and accuracy were found to be 68%, 80% and 74%, respectively.