摘要目的 探讨磁化传递成像(MTI)评估克罗恩病(CD)患者肠壁炎症和纤维化的价值.方法 前瞻性收集2014年7月至2017年4月中山大学附属第一医院,因肠梗阻等并发症行择期手术,获得了病理结果,且术前15 d内行MR肠道成像(MRE)和MTI检查,手术标本与MRE图可行区域区域定位的31例临床确诊CD患者.患者均行常规MRE和MTI屏气扫描,测量病变肠壁MTR.采用MTI和手术切除肠道区域区域定位的方法,切取肠壁行HE(评估肠壁炎症)、Masson(评估肠壁纤维化)和Ⅰ型胶原蛋白染色(评估肠壁内Ⅰ型胶原蛋白的沉积情况),选取病理切片上病变最严重的区域进行评分,分别为0分(正常)、1分(轻度)、2分(中度)、3分(重度).采用Spearman相关或偏相关分析评价肠壁MTR与各组织学评分的相关性,采用单因素方差分析比较4组不同纤维化程度肠壁MTR的差异,采用ROC评估MTR诊断肠壁纤维化的效能,采用独立样本t检验比较纯炎症组和混合炎症纤维化组肠壁MTR的差异.结果 31例共纳入62个肠壁全层标本,纯炎症标本9个,混合炎症纤维化标本53个.无纤维化患者肠壁MTR为(21.45±2.65)%,轻度、中度、重度纤维化患者的MTR分别为(30.88±6.14)%、(35.14±4.31)%、(39.44±4.17)%,差异有统计学意义(F=38.397,P<0.01).肠壁MTR与纤维化评分具有较好的相关性(r=0.681,P<0.01).MTR鉴别中、重度纤维化和无轻度纤维化具有高准确性,ROC下面积为0.905,以MTR=31.50%为阈值,诊断的敏感度为93.6%,特异度为80.0%.纯炎症组肠壁MTR为(21.45±2.65)%,混合炎症纤维化肠壁MTR为(36.28±5.21)%,混合组肠壁MTR高于纯炎症组,差异有统计学意义(t=-13.052,P<0.01).肠壁MTR和Ⅰ型胶原蛋白评分呈轻度正相关(r=0.325,P=0.044);肠壁MTR和炎症评分不具有相关性(r=-0.024,P=0.857).结论 MTI可定量评估CD患者的肠道纤维化,并可鉴别纯炎症和混合炎症纤维化CD.

abstractsObjective To assess the diagnostic value of magnetization transfer MRI (MTI) for bowel inflammation and fibrosis in humans with Crohn disease (CD). Methods From July 2014 through April 2017, 31 patients with a confirmed diagnosis of CD were prospectively recruited from the First Affiliated Hospital of Sun Yat Sen University. They were scheduled for elective surgery due to bowel obstruction and other complications, and underwent preoperative MR enterography (MRE) and MTI within 15 days of surgery. All cases had available intestinal specimens identified on MRE and resected bowel segments for region by region matching. All patients underwent breath hold conventional MRE and MTI examinations, and then the magnetization transfer ratios (MTRs) of pathological bowel segments were measured. Using region by region correlation between MTI and surgical specimen, the bowel segments were resected to stain with HE for evaluating bowel inflammation, Masson for bowel fibrosis, and typeⅠcollagen staining for the deposition of typeⅠcollagen within the bowel walls. The histologic sections from the most severe areas were scored as 0 (normal), 1 (mild), 2 (moderate) and 3 (severe). The correlations between MTR and histologic scores were analyzed by using Spearman rank correlation or partial correlation. The differences in MTR among different grades of bowel fibrosis were analyzed by one way ANOVA. The efficacy of MTR for predicting bowel fibrosis was evaluated by receiver operating characteristic curves analysis. The difference in MTRs between purely inflammatory bowel walls and mixed fibrotic and inflammatory bowel walls was analyzed by Student s t test. Results Sixty two resected bowel specimens from 31 patients including 9 purely inflammatory bowel walls and 53 mixed fibrotic and inflammatory bowel walls were obtained in this study. There were significant differences in MTR among non fibrotic [(21.45 ± 2.65)%], mildly [(30.88 ± 6.14)%], moderately [(35.14 ± 4.31)%] and severely [(35.14 ± 4.31)%] fibrotic walls (F=38.397,P<0.01). MTRs strongly correlated with fibrosis scores (r=0.681, P<0.01). High accuracy of MTRs was shown (curve under area=0.905, P<0.01) for differentiating moderately severely fibrotic from non fibrotic and mildly fibrotic bowel walls. Using MTR of 31.50% as a cutoff value, the sensitivity and specificity were 93.6% and 80.0%, respectively. The MTRs of purely inflammatory bowel walls [(21.45 ± 2.65)%] were significantly higher than that of mixed fibrotic and inflammatory [(36.28±5.21)%] bowel walls (t=-13.052,P<0.01). MTRs correlated with the scores of type Ⅰ collagen (r=0.325, P=0.044) but did not correlate with inflammation scores (r=-0.024, P=0.857). Conclusions MTI enables quantitative evaluation of bowel fibrosis in patients with CD and can be used to differentiate purely inflammatory CD from mixed fibrotic and inflammatory CD.