The evaluation of sacroiliitis using Tc-99m-nanocolloid and Tc-99m-MDP scintigraphy

The role of imaging studies in the evaluation of patients with sacroiliitis is controversial. We aimed to evaluate the role of nanocolloid and bone sc intigraphy in patients with sacroiliitis and to investigate the clinical re levance of imaging findings. Thirty-two patients with clinically sacroiliac disease (nine females, 23 males, aged 22-47 years) underwent scintigraphic and radiographic examinations and all imaging studies were performed withi n 2 weeks. Twenty-five subjects were also included as a control group (10 f emales, 15 males, aged 20-51 years) for quantitative analysis of the hone s can. The quantitative analysis was done by using regions of interest drawn over the right and left sacroiliac (ST) joint and sacrum (S) and SI/S ratio s were calculated. Abnormal uptake was defined as an uptake higher than the mean +/- 2 SD of the control SI/S values. Bone scintigraphy was performed using a three-phase technique and single photon emission computed tomograph y (SPECT). Nanocolloid scintigraphy (NS) was performed 1 h later, after adm inistration of 370 MBq Tc-99m-nanocolloid, and evaluated visually. Each of the scintigraphic examinations was performed on separate days within the sa me week. Sensitivity values were 25%, 47%, 69% and 97%, and specificity val ues were 80%, 90%, 95% and 90% in quantitative bone scanning (QBS), Tc-99m- NS, planar and SPECT bone imaging, respectively, when the clinical findings were considered as the 'gold standard'. Our results showed that bone SPECT scanning was more sensitive than planar imaging, but planar imaging was th e most specific method. SPECT was also the most associated technique with c linical findings. Tc-99m-NS was neither specific nor sensitive enough in th e detection of sacroiliitis although it could be helpful fur the confirmati on of inflammation. ((C) 2001 Lippincott Williams & Wilkins).