Quantitative sacroiliac joint scintigraphy. A critical assessment.

With quantitative sacroiliac joint scintigraphy (QSS), sacroiliac joint-to-sacrum (SIS) ratios greater than or equal to 1.40 are abnormal for our method. High SIS ratios are associated with roentgenographically appreciated sacroiliitis and with early clinically evident sacroiliitis. Although highly sensitive, QSS abnormalities are not specific for inflammatory sacroiliac (SI) joint disease. High SIS ratios are also seen in rheumatoid arthritis, degenerative abnormalities of the lumbosacral spine, and metabolic bone disorder. Other disorders with roentgenographic SI joint abnormalities must be studied scintigraphically before QSS can be employed as a useful diagnostic test.