Assessment of quantitative SPECT 99mTc labelled white cell scans to monitor response to treatment of inflammatory bowel disease:

Aim To assess the efficacy of repeat quantitative SPECT white cell scans (WCSs) for assessing response to therapy in patients with active inflammatory bowel disease (IBD). It has been shown that quantitative SPECT WCSs correlate very well with histology, the recognized ‘gold standard’ for assessing the severity of IBD. Methods The final study group consisted of 21 subjects with active IBD. SPECT 99mTc labelled white cell scans were performed immediately prior to and 2 weeks after initiation of anti-inflammatory treatment. Image processing was performed by 2 observers blinded to the identity of the subjects. Uniform attenuation correction was applied. SPECT scores (the ratio of the maximal bowel uptake to that of the hottest vertebral bone marrow segment) were obtained for ‘pre’ scans and repeated for the same bowel segment in ‘post’ scans. Results SPECT scores were recorded in the range of approximately 0–7 and correlation between observers for repeat SPECT scores was good (r2=0.87). Two of 23 (9%) decreased, 6/23 (28%) showed little change and 15/23 (65%) improved with a range of SPECT score differences of up to 3. Conclusion We have shown that the use of repeat quantitative SPECT WCSs is a reproducible method that may be used to assess the direction and magnitude of the response to treatment.