The effects of N-butylscopolamine on bowel uptake:: an 18F-FDG PET study

Purpose To determine the effect of N-butylscopolamine (buscopan) on intestinal uptake of F-18-FDG. Methods Seventy-two oncology patients were prospectively studied and 36 patients received 20 mg of N-butylscopolamine intravenously. All patients were imaged with a Siemens PET scanner. After a 4-h fast, patients were injected with FDG and then scanned 1 h post-injection. Two experienced observers interpreted all studies independently. Scans were scored visually, grading F-18-FDG bowel uptake (0-3) and the influence of bowel uptake to a lack of confidence in scan reporting (0-3). For semi-quantitative comparison, the ratio of radiotracer uptake in the bowel to mean liver (B/L) was obtained. Results All results were in favour of N-butylscopolamine. For the qualitative data, a Mann-Whitney test was used. Results for contribution of bowel uptake to lack of confidence in reporting scores, showed P=0.0001 for observer 1, and P=0.002 for observer 2; for degree of uptake in bowel scores, observer I results gave a value of P=0.0001 and observer 2 P=0.001. For agreement of uptake scores, Kappa index showed 'moderate' agreement between observers for the control group and 'fair' agreement for the N-butylscopolamine group. For contribution of bowel uptake to lack of confidence scores, there was 'very good' agreement for the control group and 'fair' agreement for the N-butylscopolamine group. The semi-quantitative effect of N-butylscopolamine on bowel-to-liver ratio was determined using an unrelated t-test that produced significance at the level of P < 0.001. Conclusion This study showed that administration of N-butylscopolamine can reduce artefacts in the bowel during F-18-FDG PET, and can potentially improve accuracy of F-18-FDG PET reporting.