Effect of N-butylscopolamine on intestinal uptake of fluorine-18-fluorodeoxyglucose in PET imaging of the abdomen

Aim: Circumscribed or diffuse intestinal uptake of F-18-fluorodeoxyglucose (FDG) is a frequent finding in PET imaging of the abdomen often interfering with correct scan interpretation. The aim of the present study was to dete rmine whether the antiperistaltic agent N-butylscopolamine reduces intestin al FDG-uptake. Methods: Whole body scans from 40 patients with malignant ly mphoma and no evidence for intraabdominal tumor involvement were analyzed ( 6 bed positions; scan start 60 min post injection of approximately 350 MBq FDG; emission time 9 min per position; no attenuation correction). Twenty p atients received 20 mg N-butylscopolamine in combination with on intravenou s injection of FDG (test group) and 20 patients received only FOG (control group). For analysis, the intensity of bowel loops and diffuse abdominal ba ckground were compared to normal liver on a 4 point scale (0 = lowest inten sity, 3 = highest) by two experienced nuclear medicine physicians. Furtherm ore, focal intestinal uptake was evaluated quantitatively by a ROI techniqu e and bower to liver ratios (b/l) were calculated. Results: Dowel loops hod lower intensity and occupied less abdominal legions in the test group then in the control group (visual score 1 vs. 1.5, p = 0.01; abdominal regions 1 of 5 vs. 2.5 of 5, p = 0.04). The visual score for diffuse abdominal back ground was 0.5 in the test group and 1 in the control group (p = 0,04). Dow el uptake interfered with scan interpretation in 1 of 20 patients in the te st group and 6 of 20 patients in the control group (p = 0.01). The b/l rati os were 1.5 +/- 0.7 in the test group and 2.3 +/- 1.4 in the control group (p = 0.08). Conclusion: Administration of N-butylscopolamine reduces intest inal uptake of FDG and may facilitate accurate interpretation of abdominal FDG-PET studies.