Diagnostic value of quantitative sacroiliac joint scintigraphy in brucellosis

Increased bone activity in the sacroiliac joints has been shown to be a sen sitive method for detecting sacroiliitis in brucellosis. Because symmetrica lly increased uptake usually is difficult to detect, this study was perform ed to improve the sensitivity by quantifying sacroiliac joint uptake. Quant ification was accomplished by normalizing sacroiliac joint activity to acti vity in the lumbar spine and sacrum. From rectangular regions of interest o ver a standardized posterior pelvic view, the ratios of the sacroiliac:lumb ar spine and sacroiliac:sacrum were calculated. Abnormal sacroiliac joint u ptake was defined as uptake greater than the mean +2 SD of normal. This was applied to 79 patients with brucella sacroiliitis. The quantitative approa ch was compared with visual interpretation. Of the 16 patients in the age g roup of 5 to 19 years, 7 patients had Visual evidence of sacroiliitis and 9 patients had positive evidence by sacroiliac-sacrum and 12 by sacroiliac-l umbar spine quantification. Of 21 patients who were 20 to 30 years old, 10 patients had positive visual evidence, whereas 17 and 20 patients had posit ive evidence of sacroiliitis by sacroiliac-sacrum and sacroiliac-lumbar spi ne, respectively. Of 42 patients who were 31 to 85 years old, 24, 32, and 3 6 patients had positive evidence of sacroiliitis by visual inspection, sacr oiliac-sacrum, and sacroiliac-lumbar spine, respectively. Thus, the quantit ative approach increased the sensitivity in diagnosing Brucella sacroiliiti s in all age groups by 31.3%, 47.6%, and 28.6%, respectively, for sacroilia c-lumbar spine and by 12.5%, 33.3%, and 19%, respectively, for sacroiliac-s acrum.