Aim: To evaluate (99m)Tc-ciprofloxacin scintigraphy compared with computed tomography (CT) for detecting secondary infections associated with severe acute pancreatitis (SAP) in swine.
Methods: Six healthy swine were assigned to a normal control group (group A, n = 6). SAP was induced in group B (n = 9) and C (n = 18), followed by inoculation of the resulting pancreatic necroses with inactive Escherichia coli (E. coli) (group B) and active E. coli (group C), respectively. At 7 d after inoculation, a CT scan and a series of analyses using infecton imaging (at 0.5, 1, 2, 3, 4 and 6 h after the administration of 370 MBq of intravenous infecton) were performed. The scintigrams were visually evaluated and semi-quantitatively analyzed using region of interest assignments. The differences in infecton uptake and changes in the lesion-background radioactive count ratios (L/B) in the 3 groups were recorded and compared. After imaging detection, histopathology and bacterial examinations were performed, and infected SAP was regarded as positive. The imaging findings were compared with histopathological and bacteriological results.
Results: In group A, 6 animals survived without infection in the pancreas. In group B, 7/9 swine survived and one suffered from infection. In group C, 15/18 animals survived with infection. Hence, the number of normal, non-infected and infected SAP swine was 6, 6 and 16, respectively. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of the infecton method were 93.8% (15/16), 91.7% (11/12), 92.9% (26/28), 93.8% (15/16) and 91.7% (11/12), whereas these values for CT were 12.5% (2/16), 100.0% (12/12), 50.0% (14/28), 100.0% (2/2) and 46.2% (12/26), respectively. The changes in L/B for the infected SAP were significantly different from those of the non-infected and normal swine (P < 0.001). The mean L/B of the infectious foci at 0.5, 1, 2, 3, 4 and 6 h was 1.17 ± 0.10, 1.71 ± 0.30, 2.46 ± 0.45, 3.36 ± 0.33, 2.04 ± 0.37 and 1.1988 ± 0.09, respectively. At 3 h, the radioactive counts (2350.25 ± 602.35 k) and the mean L/B of the infectious foci were significantly higher than that at 0.5 h (P = 0.000), 1 h (P = 0.000), 2 h (P = 0.04), 4 h (P = 0.000) and 6 h (P = 0.000).
Conclusion: (99m)Tc-ciprofloxacin scintigraphy may be an effective procedure for detecting SAP secondary infections with higher sensitivity and accuracy than CT.
Keywords: Ciprofloxacin; Infection; Pancreatitis; Radionuclide imaging; X-ray computed tomography.