A radiopharmaceutical and clinical comparison of 99mTc-Sn-hydroxymethylene diphosphonate with 99mTc-Sn-hydroxyethylidene diphosphonate.

A comparison of 99mTc labeled hydroxyethylidene diphosphonate (99mTc-HEDP) and hydroxymethylene diphosphonate (99mTc-HMDP), two bone scanning agents differing by a single methyl group, was performed in 20 patients. In nine patients, no difference in scan quality was found. Of the other 11, HMDP had significantly better bone delineation (p = 0.012), lower soft tissue background (p = 0.001), and improved overall scan quality (p = 0.012) in 10, while HEDP was preferred for bone delineation and overall quality in only a single patient. No significant difference in lesion detection was noted.