Purpose: To establish the experimental model of ulcerative colitis induced by dextran sodium sulphate (DSS), and to develops a preclinical MRI imaging method for evaluating mucosal damage of colitis by rectal administration of Gd - nanoCPs. Methods: Gd - nanoCPs were prepared using a modified emulsion coalescence method. Rat model of ulcerative colitis was induced in Sprague Dawley rat by administration of 5% DSS in drinking water. Normal group (n = 14) and colitis group (n = 14) were rectal administered with Gd - nanoCPs suspension (n = 10 for each group) or Gd - DTPA aqueous solution (n = 2 for each group), or were injected with Gd - DTPA via the caudal vein(n = 2 for each group) . MRI scans were performed before and 20 to 120 minutes after the infusion for each groups. Signal intensity (SI) values of ROIs in the wall of rectum and colon, muscles of the pelvis near the rectum and background of the imaging were measured and the corresponding relative SI values were calculated. Relative SI valuesin distal, middle and proximal colon between the groups and pre - and post infusion were compared with paired t - test respectively. Results: When Gd - nanoCPs were administered rectally for normal and colitis rats, increase of MRI signal intensity in the colon wall was detected from 20 to 120min after infusion. Colon mucosa enhancement rates in distal, middle and proximal colon were about 1.8% -35.2%,1.6% ~ 26.4%, 1.8%-27.3% for normal group, and 25.2% ~ 71.1% , 20.8% - 55. 7% , 9.4% - 35.1% for colitis group, respectively. The difference of MRI signal intensity was significant between inflamed colons and normal colons(all P < 0.05) . Conclusion: Gd - nanoCPs is a potential excellent candidate for biospecific diagnostic tools as well in MRI for evaluating colitis.%目的:建立右旋葡聚糖硫酸钠(DSS)诱导的大鼠溃疡性结肠炎模型,探索经直肠灌注Gd - nanoCPs检测炎性肠病的预临床方法.方法:采用改良的乳化凝结技术合成Gd - nanoCPs.采用5％葡聚糖硫酸钠诱导溃疡性结肠炎大鼠模型.对正常组(n=1 4)、结肠炎组(n=14)分别灌注Gd - nanoCPs混悬液(10只),Gd - DTPA水溶液(2只)及尾静脉注射Gd - DTPA(2只),于灌肠前和灌肠20～ 120min后行结肠MR扫描.对结肠上段、中段及下段肠壁分别进行灌肠前后结肠壁、盆壁肌肉和图像背景MR信号强度进行测量,计算灌肠前后肠壁与盆壁肌肉的相对信号值及强化率,并采用配对t检验进行组间比较.结果:直肠灌注Gd - nanoCPs混悬液20～120min内肠黏膜均有强化,20～ 120min内下段、中段及上段结肠黏膜强化率分别为1.8％～35.2％、1.6％ ～26.4％、1.8％ ～ 27.3％和25.2％～71.1％、20.8％ ～ 55.7％、9.4％～35.1％.两组差异有统计学意义(P＜0.05).结论:Gd - nanoCPs作为一种新型肠道MRI对比剂,具有成为检测炎性肠病的特异性靶向MRI造影剂的潜能.
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