莊小芳, 孫 潔, 王曉波, 王 燕, 吳琦琦, 王曉忠
(1 新疆維吾爾自治區(qū)中醫(yī)醫(yī)院 肝病科, 烏魯木齊 830000;2 新疆烏魯木齊市中醫(yī)醫(yī)院 老年病科, 烏魯木齊 830000)
瞬時彈性成像技術(shù)診斷非酒精性脂肪性肝病的性能評估
莊小芳1, 孫 潔2, 王曉波1, 王 燕1, 吳琦琦1, 王曉忠1
(1 新疆維吾爾自治區(qū)中醫(yī)醫(yī)院 肝病科, 烏魯木齊 830000;2 新疆烏魯木齊市中醫(yī)醫(yī)院 老年病科, 烏魯木齊 830000)
目的探討瞬時彈性成像技術(shù)在非酒精性脂肪性肝病(NAFLD)患者診斷中的應用價值。方法納入2016年6月-2016年12月新疆維吾爾自治區(qū)中醫(yī)醫(yī)院無脂肪肝患者29例,NALFD患者92例,采集患者的一般資料,計算BMI,進行血常規(guī)、肝功能、血脂、血清胰島素、AFP檢測,并行肝臟CT、FibroTouch檢測;以肝/脾CT比值為診斷標準繪制受試者工作特征曲線(ROC曲線),應用ROC曲線判斷受控衰減參數(shù)(CAP)診斷NAFLD的能力,計算ROC曲線下面積(AUC),其診斷有效性檢測采用Z檢驗,并利用約登指數(shù)確定最佳截斷值。符合正態(tài)分布的計量資料2組間比較采用t檢驗,多組間比較采用單因素方差分析,進一步兩兩比較采用LSD-t檢驗;非正態(tài)分布的計量資料2組間比較采用Mann-WhitneyU檢驗,多組間比較采用Kruskal-WallisH檢驗。計數(shù)資料組間比較采用χ2檢驗。結(jié)果無脂肪肝組以及不同程度NAFLD組患者的年齡、ALT、AST、血清胰島素、脂肪衰減、肝臟硬度比較,差異均有統(tǒng)計學(P值均<0.05)。重度NAFLD組年齡明顯低于無脂肪肝組(P<0.001)。CAP在無脂肪肝組與不同程度NAFLD組間比較,差異均有統(tǒng)計學意義(P值均<0.001),但中度及重度NAFLD組之間CAP比較,差異無統(tǒng)計學意義(P=0.127)。無脂肪肝組分別與中度、重度NAFLD組的肝臟硬度值比較,差異均有統(tǒng)計學意義(P值分別為0.034、<0.001),但中度與重度脂肪肝組間比較,差異無統(tǒng)計學意義(P=0.327)。無脂肪肝組分別與各程度NAFLD組比較ALT和AST水平差異均有統(tǒng)計學意義(P值均<0.001),且重度NAFLD組的ALT、AST水平均高于輕度NAFLD組(P值均=0.001)。無脂肪肝組分別與各程度NAFLD組比較,胰島素水平差異均有統(tǒng)計學意義(P值均<0.05),但不同程度NAFLD組之間胰島素水平差異無統(tǒng)計學意義(P值均>0.05)。CAP診斷輕度、中度、重度NALFD的最佳cut-off值分別是244 dB/m、272 dB/m、272 dB/m,AUC及其95%可信區(qū)間分別為0.778(0.663~0.894)、0.893(0.809~0.976)、0.942(0.886~0.998),P值均<0.001。結(jié)論瞬時彈性成像技術(shù)可作為無創(chuàng)性診斷NAFLD的可靠手段,CAP可定量準確評估NALFD程度,對NALFD的分級診斷有較好的應用價值,能有效地區(qū)分輕度和中度以上NALFD;但難以區(qū)分中度和重度NALFD。
非酒精性脂肪性肝??; 彈性成像技術(shù); 診斷
非酒精性脂肪性肝病(NAFLD)是指除外酒精和其他明確的肝損傷因素所致的,以彌漫性肝細胞大泡性脂肪變?yōu)榕R床病理綜合征的獲得性代謝應激性肝損傷[1]。主要表現(xiàn)為肝臟脂肪過量堆積,并伴胰島素抵抗,組織學存在5%以上的肝脂肪變性[2]。現(xiàn)NAFLD已成為世界公共衛(wèi)生問題,平均患病率達24.4%,我國患病率達15%~20%[3-4]。NAFLD的演變包括單純性非酒精性脂肪肝,以及由其進展而來的非酒精性脂肪性肝炎、肝硬化,甚至肝癌。因此,對NAFLD的早期診斷和治療,對判斷預后有一定指導意義。目前,除肝活組織檢查外,對NAFLD的診斷及程度評估主要依靠影像學檢查。臨床常用的影像學檢查方法有B超、CT、具有化學位移成像的MRI、氫質(zhì)子磁共振波譜分析(1H-MRS)及瞬時彈性成像技術(shù)。本文主要以CT為診斷標準評估瞬時彈性成像技術(shù)對NAFLD的診斷價值。
1.1 研究對象 納入2016年6月-2016年12月于新疆維吾爾自治區(qū)中醫(yī)醫(yī)院體檢人員,包括NAFLD患者和健康對照者。NAFLD診斷符合《非酒精性脂肪性肝病診療指南(2010年修訂版)》[5]。排除標準:(1)年齡<18歲;(2)飲酒量男性超過30 g/d,女性超過20 g/d;(3)孕婦;(4)病毒性肝炎、藥物性肝炎、自身免疫性肝炎、代謝性肝病、肝癌、失代償性肝病、艾滋病。
1.2 研究方法
所有入選對象均行肝臟CT檢查及瞬時彈性成像檢測(采用FibroTouch檢測),并計算BMI,進行血常規(guī)、肝功能、血脂、血清胰島素、AFP檢查。
1.2.1 脂肪肝CT診斷標準 取門靜脈主干入肝的層面,測肝、脾CT值。按肝、脾CT值的比值,分為無脂肪肝(比值≥1.0),輕度脂肪肝(0.7<比值<1.0),中度脂肪肝(0.5<比值≤0.7)和重度脂肪肝(比值≤0.5)[5]。
1.2.2 血樣采集方法 采集患者的空腹靜脈血,檢測肝功能及其他相關生化指標。肝功能采用全自動生化分析儀及其配套試劑檢測。整個操作過程均嚴格按照試劑盒說明書與儀器的操作手冊進行。
1.2.3 肝臟瞬時彈性掃描 采用FibroTouch-B型(無錫海斯凱爾醫(yī)學技術(shù)有限公司)測量患者肝臟硬度值及受控衰減參數(shù)(controlled attenuation parameter, CAP),具體方法參照FibroTouch用戶操作手冊。
2.1 NALFD組與對照組基線情況 共入組121例研究對象,年齡18~25歲。其中無脂肪肝組29例(24.0%),NALFD組92例(76.0%)[輕度NALFD組33例(27.3%),中度NALFD組31例(25.6%),重度NALFD組28例(23.1%)]。2組間肝臟硬度、ALT、AST、胰島素水平比較,差異均有統(tǒng)計學意義(P值均<0.05),2組間性別、年齡及BMI比較差異均無統(tǒng)計學意義(P值均>0.05)(表1)。
2.2 不同程度NAFLD之間檢測指標比較 比較無脂肪肝組以及不同程度NAFLD相關檢測指標,提示NAFLD程度與年齡、CAP、肝臟硬度值、ALT、AST、血清胰島素水平有關。重度NAFLD組年齡均值明顯低于無脂肪肝組(P<0.001)。CAP在無脂肪肝組與不同程度NAFLD組間比較,差異均有統(tǒng)計學意義(P值均<0.001),可鑒別無脂肪肝、輕度及中度以上NAFLD;但中度及重度NAFLD組之間CAP比較,差異無統(tǒng)計學意義(P=0.127)。無脂肪肝組分別與中度、重度NAFLD組肝臟硬度值比較,差異均有統(tǒng)計學意義(P=0.034,P<0.001),但中度與重度脂肪肝組間比較,差異無統(tǒng)計學意義(P=0.327)。無脂肪肝組與各程度NAFLD組間ALT和AST的水平比較,差異均有統(tǒng)計學意義(P值均<0.001),且重度NAFLD組的ALT、AST水平均高于輕度NAFLD組(P值均=0.001)。無脂肪肝組與各程度NAFLD組胰島素水平比較,差異均有統(tǒng)計學意義,但不同程度NAFLD組之間胰島素水平差異無統(tǒng)計學意義(P值均>0.05)(表2)。
2.3 CAP值對各級NAFLD的診斷性能比較 以肝、脾CT比值為診斷標準,以無脂肪肝組作為對照,通過ROC曲線評估CAP對不同程度NAFLD的診斷性能。結(jié)果顯示,當截斷值為244 dB/m時,診斷輕度NAFLD的AUC為0.778,靈敏度為0.879,特異度為0.621;當截斷值為272 dB/m時,可診斷為中度以上NAFLD,但相對于中度NAFLD(AUC 0.893,靈敏度0.867,特異度 0.828),CAP對重度NAFLD診斷的準確性更高(AUC 0.942,靈敏度 0.964,特異度 0.828)(表3,圖1~3)。
表1 無脂肪肝組與NAFLD組基線情況比較
注:HGB,糖化血紅蛋白;CHOL,總膽固醇;FBG,空腹血糖
表2 無脂肪肝組和不同NAFLD組之間相關檢測指標比較
注:1)與無脂肪肝組比較,P<0.05; 2)與輕度NAFLD組比較,P<0.05; 3)與中度NAFLD組比較,P<0.05
表3 CAP對不同程度NAFLD的診斷價值比較
注:95%CI,95%可信區(qū)間;Z=AUC面積差/標準誤
圖1 CAP診斷輕度NAFLD的ROC曲線
圖2 CAP診斷中度NAFLD的ROC曲線
圖3 CAP診斷重度NAFLD的ROC曲線
據(jù)統(tǒng)計,25%的脂肪肝患者肝纖維化程度逐漸進展,6%的患者最終進展至肝硬化[6],對于NAFLD的早期篩查診斷至關重要。肝活組織檢查雖為診斷NAFLD的金標準,由于其有創(chuàng)性、存在抽樣誤差,同時難以重復評價,臨床應用存在局限性,故臨床多以影像學檢查評估脂肪肝病變程度。
B超具有安全、無創(chuàng)的特點,其診斷脂肪肝的靈敏度可達60%~94%,特異度66%~97%[7],但當肝脂肪變程度<30%時超聲難以檢出,且操作者主觀性判斷,存在一定診斷誤差,同時難以區(qū)分非酒精性脂肪性肝炎和單純性非酒精性脂肪肝,不能有效判斷肝組織學病變程度。MRI可較好地評估肝脂肪變性程度,并和病理檢查有很好的相關性,能檢測出低至3%的肝脂肪變性,靈敏度和特異度分別為76.7%~90.0%和87.1%~91.0%[8]。1H-MRS與CT對肝臟脂肪含量的檢測具有高度的相關性,并且兩者均與組織學評分關聯(lián)良好[9]。Baneriee等[10]報道,肝組織學和1H-MRS比較,NAFLD患者脂肪變性Brunt≥1,1H-MRS診斷靈敏度為80%,特異度為100%,對于重度脂肪變性Brunt>2的患者,其靈敏度為100%,特異度為97%。由于上述檢查價格昂貴,臨床尚不能廣泛用于評估肝臟脂肪變性。CT對脂肪肝診斷,靈敏度可達82%,特異度100%[11],比B超更具優(yōu)勢。然而CT具有輻射性,短期重復檢查難度大,且不適用于孕婦及兒童患者,臨床用于脂肪肝篩查及治療評估存在困難。瞬時彈性成像具有快速、精確性高、重復性好等優(yōu)點,對肝纖維化程度可瞬時、客觀、有效、定量評估,大大減少了肝穿刺的必要性,已廣泛應用于多種慢性肝病肝纖維化程度的評估[12]。以瞬時彈性成像為基礎的CAP是一種特定用于評估脂肪肝的新型工具,在初期臨床試驗中提示有良好診斷價值[13]。國內(nèi)已有研究[14]結(jié)果證明CAP能夠識別超過5%的肝臟脂肪變性,并認為CAP能夠替代普通超聲檢查用于脂肪肝的流行病學調(diào)查。目前臨床多用FibroScan或FibrTouch進行檢測。
本研究數(shù)據(jù)結(jié)果顯示,重度NAFLD組患者平均年齡偏低,呈年輕化趨勢?;€數(shù)據(jù)顯示,無脂肪肝組及各級NAFLD組BMI均值均>25 kg/m2,但BMI與NAFLD程度無統(tǒng)計學差異。結(jié)合新疆地域特點及高脂高鹽飲食習慣,冬季時間長,戶外活動時間短,導致脂肪的過度堆積,全身體脂分布異常,而非單純肝臟脂肪過度沉積所致。隨著NAFLD程度加重,ALT、AST、胰島素水平呈上升趨勢,提示NAFLD的發(fā)生與發(fā)展與上述因素密切相關,胰島素抵抗存在于NAFLD發(fā)生發(fā)展的整個過程,在輕度與重度NAFLD之間,ALT、AST水平的升高,間接反映肝脂肪變性的炎癥狀態(tài),并存在代謝應激性肝損傷,提示可能進展為非酒精性脂肪性肝炎。另外,識別和定量肝纖維化分期具有重要臨床意義,肝纖維化程度可作為疾病診斷及隨訪過程病情評估的重要指標之一。而NAFLD預后取決于肝組織學特征,是否存在非酒精性脂肪性肝炎,伴或不伴肝纖維化[15-16]。本研究應用FibroTouch進行纖維化及CAP檢測,結(jié)果提示FibroTouch對中到重度肝脂肪變診斷性能較高,對輕度肝脂肪變的診斷性能較低,且誤診率較高。CAP作為診斷脂肪肝的新技術(shù),可鑒別中度以上肝脂肪變,但對于中度及重度肝脂肪變的區(qū)分,仍存在一定的局限性,與相關學者[14,17-19]研究結(jié)果一致,考慮與BMI和皮膚至肝包膜距離等因素相關。相對于中度NAFLD,CAP對重度NAFLD診斷的準確性更高。
瞬時彈性成像可作為無創(chuàng)性診斷NAFLD的可靠手段,CAP可定量準確評估脂肪肝程度,對NAFLD的分級診斷有較好的應用價值。然而,由于樣本量少及性別偏倚,且相關技術(shù)尚無標準化規(guī)范,無統(tǒng)一界值提供臨床參考,數(shù)據(jù)結(jié)果仍有待大樣本高質(zhì)量臨床研究進行分析,并可針對特殊脂肪肝人群(合并慢性乙型肝炎、慢性丙型肝炎、酒精性脂肪肝、代謝綜合征、兒童、青少年等)進行深入分析,以探討不同人群肝脂肪病變特點。本研究提示,CAP區(qū)分中度及重度NAFLD存在局限性,在臨床研究中,可考慮增大樣本量,調(diào)整數(shù)據(jù)均衡性,進一步聯(lián)合瞬時彈性成像及多個相關生物學標志物建立診斷模型,以提高診斷肝脂肪變的準確性,預測疾病危險因素,評估疾病發(fā)展及預后。
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Performanceoftransientelastographyindiagnosisofnonalcoholicfattyliverdisease
ZHUANGXiaofang,SUNJie,WANGXiaobo,etal.
(DepartmentofHepatology,TraditionalChineseMedicineHospitalofXinjiangUygurAutonomousRegion,Urumqi830000,China)
ObjectiveTo investigate the value of transient elastography (TE) in the diagnosis of nonalcoholic fatty liver disease (NAFLD).MethodsA total of 21 patients without fatty liver disease and 92 patients with NAFLD, who visited Traditional Chinese Medicine Hospital of Xinjiang Uygur Autonomous Region from June to December, 2016, were enrolled. Their general information was collected and body mass index (BMI) was calculated. Routine blood test, liver function evaluation, and measurement of blood lipid, serum insulin, and alpha-fetoprotein were performed, and liver CT and FibroTouch were performed. The receiver operating characteristic (ROC) curve was plotted with liver/spleen CT ratio as diagnostic criteria, and the ROC curve was used to evaluate the ability of controlled attenuation parameter (CAP) to diagnose NAFLD. The area under the ROC curve (AUC) was calculated, theZtest was used to evaluate diagnostic effectiveness, and Youden index was used to determine the optimal cut-off value. Thet-test was used for comparison of normally distributed continuous data between two groups; a one-way analysis of variance was used for comparison between multiple groups, and the least significant differencet-test was used for further comparison between any two groups. The Mann-WhitneyUtest was used for comparison of non-normally distributed continuous data between two groups, and the Kruskal-WallisHtest was used for comparison between multiple groups. The chi-square test was used for comparison of categorical data between groups.ResultsThere were significant differences in age, alanine aminotransferase (ALT), aspartate aminotransferase (AST), serum insulin, fat attenuation, and liver stiffness measurement (LSM) between the patients without fatty liver disease and those with varying degrees of NAFLD (allP<0.05). The severe NAFLD group had a significantly lower mean age than the non-fatty liver disease group (P<0.001). There was a significant difference in CAP between the non-fatty liver disease group and the groups with varying degrees of NAFLD (allP<0.001), while there was no significant difference in CAP between the moderate and severe NAFLD groups (P=0.127). There was a significant difference in LSM between the non-fatty liver disease group and the moderate NAFLD group (P=0.034), as well as between the non-fatty liver disease group and the severe NAFLD group (P<0.001), while there was no significant difference between the moderate and severe NAFLD groups (P=0.327). There were significant differences in the levels of ALT and AST between the non-fatty liver disease group and the groups with varying degrees of NAFLD (allP<0.001), and the severe NAFLD group had significantly higher levels of ALT and AST than the mild NAFLD group (bothP=0.001). There was a significant difference in the level of insulin between the non-fatty liver disease group and the groups with varying degrees of NAFLD, while there was no significant difference between the groups with varying degrees of NAFLD (allP>0.05). The optimal cut-off values of CAP for the diagnosis of mild, moderate, and severe NAFLD were 244 dB/m, 272 dB/m, and 272 dB/m, respectively, with AUC of 0.778 (95% confidence interval [CI]: 0.663-0.894), 0.893 (95%CI: 0.809-0.976), and 0.942 (95%CI: 0.886-0.998) (allP<0.001).ConclusionTE is a reliable noninvasiveness method for the diagnosis of NAFLD. CAP can accurately and quantitatively evaluate the degree of NAFLD and effectively differentiate mild NAFLD from moderate or severe NAFLD and thus has a good value in the grading of NAFLD. But it is difficult to differentiate moderate NAFLD from severe NAFLD.
nonalcoholic fatty liver disease; elasticity imaging techniques;diagnosis
R575.5
A
1001-5256(2017)12-2366-06
10.3969/j.issn.1001-5256.2017.12.022
2017-08-14;修回日期:2017-08-29。 基金項目:新疆維吾爾自治區(qū)科技援疆計劃(2016E02067) 作者簡介:莊小芳(1981-),女,主治醫(yī)師,主要從事中西醫(yī)結(jié)合肝病研究。 通信作者:王燕,電子信箱:112200141@qq.com。
引證本文:ZHUANG XF, SUN J, WANG XB, et al. Performance of transient elastography in diagnosis of nonalcoholic fatty liver disease[J]. J Clin Hepatol, 2017, 33(12): 2366-2371. (in Chinese)
莊小芳, 孫潔, 王曉波, 等. 瞬時彈性成像技術(shù)診斷非酒精性脂肪性肝病的性能評估[J]. 臨床肝膽病雜志, 2017, 33(12): 2366-2371.
(本文編輯:朱 晶)