Detection of sacro-ilitis. A comparison between profile scanning with the use of 99m Tc pertechnetate and scintigraphy with 99m Tc diphosphonate.

Comparative evaluation of the sensitivity of 99mTc pertechnetate scanning and of 99mTc diphosphonate scintigraphy in detecting sacro-iliac arthritis (S.I.) was performed in 32 patients with definite S.I., 14 with probable S.I., and 6 with inactive S.I., 14 patients without any evidence of S.I. served as controls. Greater diagnostic accuracy was obtained by 99mTc pertechnetate scanning than with 99mTc diphosphonate scintigraphy in patients with active S.I. in the early stages before radiological changes had become evident and in patients 22 years old and younger. In patients with inactive S.I. a close correlation was found between clinical, radiological, and scintigraphical results with 99mTc diphosphonate scintigraphy. An index obtained by adding the uptake values measured by both methods in each subject yielded valuable information in patients with S.I. that is clinically difficult to differentiate.