99Tcm-ciprofloxacin imaging in detecting the secondary infection of severe acute pancreatitis / 中华核医学杂志

ABSTRACT

Objective To evaluate the characteristics of 99Tcm-ciprofloxacin and explore its feasibility in early detection of secondary infectious foci of severe acute pancreatitis (SAP).Methods Ciprofloxacin was labeled with 99Tcm.The labeling efficiency and radiochemical purity of 99Tcm-ciprofloxacin were calculated and its biodistribution in normal pigs was measured.The recruited baby pigs were divided into three groupsnormal control group (6), non-infected group (6) and infected group (16).370-400 MBq of 99Tcm-ciprofloxacin was injected into each pig intravenously.SPECT scanning was performed at 0.5, 1,2, 3, 4 and 6 h after administration.The differences of 99Tcm-ciprofloxacin uptake among groups were calculated and the tracer activity ratio of lesion-to-background was recorded at each time point.The diagnostic value of 99Tcm-ciprofloxacin SPECT imaging for the dectection of secondary infection of SAP was assessed using histopathological results as the gold standard.Variance analysis and least significant difference test were used to analyze the data.Results Both the labehing efficiency and radiochemical purity of 99Tcm-ciprofloxacin were over 90% within 6 h.Organs with rich blood supply, such as kidney, liver and spleen were the target organs for the accumulation of 99Tcm-ciprofloxacin; while no significant uptake was found in gastrointestinal tract or normal pancreas tissue of SAP.Rapid plasma clearance and renal excretion were observed.In the infected group, the lesion was visualized at 1 h after administration.The highest radioactivity ratio of lesion-to-background (3.36 ± 0.33) was at 3 h after administration, which was significantly higher than that of the other time point ( F =99.570, P ＜0.001 ).The sensitivity, specificity, positive and negative predictive values, Youden's index (YI) and Kappa value of 99Tc%ciprofloxacin imaging were 88.2% (15/17), 83.3% (5/6), 93.8% ( 15/16), 71.4% (5/7), 0.715 and 0.667 respectively.Conclusions The biodistribution of99Tcm-ciprofloxacin is suitable for imaging infectious focus of SAP.The optimal imaging time for the detection of secondary infection of SAP is 3 h after administration, with high sensitivity and specificity.