ISSN 1004-4140
CN 11-3017/P

IgG4相关硬化性胆管炎初诊患者CT和MRI表现与血清IgG4水平升高相关性研究

董力宁, 闫威, 张洁, 杨大为, 刘朋, 徐辉, 杨正汉, 王振常, 靳二虎

董力宁, 闫威, 张洁, 等. IgG4相关硬化性胆管炎初诊患者CT和MRI表现与血清IgG4水平升高相关性研究[J]. CT理论与应用研究, 2023, 32(2): 231-239. DOI: 10.15953/j.ctta.2022.158.
引用本文: 董力宁, 闫威, 张洁, 等. IgG4相关硬化性胆管炎初诊患者CT和MRI表现与血清IgG4水平升高相关性研究[J]. CT理论与应用研究, 2023, 32(2): 231-239. DOI: 10.15953/j.ctta.2022.158.
DONG L N, YAN W, ZHANG J, et al. A Study of the Correlations between CT and MRI Findings and Elevated Serum IgG4 Levels in Newly-diagnosed Patients with IgG4-related Sclerosing Cholangitis[J]. CT Theory and Applications, 2023, 32(2): 231-239. DOI: 10.15953/j.ctta.2022.158. (in Chinese).
Citation: DONG L N, YAN W, ZHANG J, et al. A Study of the Correlations between CT and MRI Findings and Elevated Serum IgG4 Levels in Newly-diagnosed Patients with IgG4-related Sclerosing Cholangitis[J]. CT Theory and Applications, 2023, 32(2): 231-239. DOI: 10.15953/j.ctta.2022.158. (in Chinese).

IgG4相关硬化性胆管炎初诊患者CT和MRI表现与血清IgG4水平升高相关性研究

基金项目: 北京市医院管理中心临床医学发展专项(定量影像研究(ZYLX202101))。
详细信息
    作者简介:

    董力宁: 女,首都医科大学附属北京友谊医院放射科住院医师,主要从事腹部疾病影像诊断,E-mail:liningdln@126.com

    靳二虎: 男,医学博士,首都医科大学附属北京友谊医院放射科主任医师、教授、博士研究生导师,主要从事医学影像诊断相关的临床、教学和科研工作,专业特长是腹盆部疾病影像诊断,E-mail:erhujin@263.net

    通讯作者:

    靳二虎*,

  • 中图分类号: R  814;R  445

A Study of the Correlations between CT and MRI Findings and Elevated Serum IgG4 Levels in Newly-diagnosed Patients with IgG4-related Sclerosing Cholangitis

  • 摘要: 目的:观察IgG4相关硬化性胆管炎(IgG4-SC)的CT和MRI表现,探究初诊患者影像特征与血清IgG4、IgG水平的关系。方法:总结50例IgG4-SC初诊患者的临床、实验室及影像资料,通过MRCP观察病变分型、管腔狭窄形态与扩张程度;增强MRI和CT观察管壁增厚、强化模式及合并其他IgG4-RD的数量,分析基线血清IgG4及IgG水平与胆管病变和合并其他IgG4-RD数量的相关性。结果:初诊41例MRCP见Ⅰ型IgG4-SC 28例,Ⅱa型11例,Ⅲ型、Ⅳ型各1例;肝外胆管狭窄端呈漏斗状37例、截断状4例,狭窄段均为长狭窄(≥1.0 cm),其中1例胰腺段狭窄伴憩室样外凸;狭窄上游胆管扩张37例,不扩张4例。初诊42例增强MRI/CT均显示肝外胆管壁连续性增厚,15例见肝内胆管壁弥漫性增厚,管壁增厚呈向心性。50例IgG4-SC均合并AIP,其他受累器官还包括肾19例、涎腺7例、腹膜后纤维化5例、肝4例、肺4例、前列腺2例、硬化性纵隔炎2例、胆囊壁增厚20例及上腹部淋巴结肿大15例。基线血清IgG4、IgG水平升高与合并其他IgG4-RD的数量呈正相关,而与胆管壁厚度、狭窄段长度不相关。结论:胆管局限性狭窄伴上游胆管扩张或不扩张以及管壁弥漫性增厚是IgG4-SC初诊患者的特征性MRI和CT表现。基线血清IgG4及IgG水平升高与胆管病变的严重程度无关,而与合并其他IgG4-RD的数量有关。
    Abstract: Objective: To observe the CT and MRI findings in newly diagnosed patients with IgG4-related sclerosing cholangitis (IgG4-SC) and explore their correlations with serum IgG4 and IgG levels. Methods: The clinical, laboratory, and imaging data of 50 newly diagnosed IgG4-SC patients were retrospectively summarized. The type of lesions, shape of lumen stenosis, degree of dilatation of the diseased bile ducts on MRCP, characteristics and enhancement patterns of the thickened bile duct walls, and the number of other coexisting IgG4-RDs on enhanced MRI and CT were observed. Subsequently, the correlations of the patients' baseline serum IgG4 and IgG levels with the severity of bile duct lesions and the number of other coexisting IgG4-RDs were analyzed. Results: Forty-one patients underwent MRCP examinations, and the following types of IgG4-SC were identified: type Ⅰ in 28 cases, type Ⅱa in 11, type Ⅲ in 1, and type Ⅳ in 1. Extrahepatic bile duct stenosis was funnel-shaped in 37 cases and truncated in 4 cases. Moreover, all the stenotic segments were long (≥1.0 cm) and one diverticulum-like outpouching was seen in the pancreatic segment stenosis. Upstream bile ducts of the stenosis showed dilatation in 37 cases, while the other 4 cases did not show this. Contrast-enhanced MRI and CT examinations showed continuous thickening of the extrahepatic bile duct walls in 42 cases, and diffuse thickening of the intrahepatic bile duct walls was simultaneously observed in 15 cases among them. The thickness of the bile duct walls was uniformly concentric. Meanwhile, other accompanying IgG4-RDs included AIP in 50 cases, kidney involvement in 19, salivary gland involvement in 7, retroperitoneal fibrosis in 5, liver involvement in 4, lung involvement in 4, prostate involvement in 2, sclerosing mediastinitis in 2, thickened gallbladder wall (without stones) in 20, and enlarged upper abdominal lymph nodes in 15 cases. Moreover, higher baseline serum IgG4 and IgG levels were positively correlated with the number of other coexisting IgG4-RDs, but not with the bile duct wall thickness and stenotic segment length. Conclusions: Localized stenosis of the bile ducts with dilatation or non-dilation of the upstream bile ducts, as well as diffuse thickening of the bile duct walls, are the MRI and CT features of newly diagnosed patients with IgG4-SC. Furthermore, higher baseline serum IgG4 and IgG levels are not related to the severity of the diseased bile ducts but are related to the number of other coexisting IgG4-RDs.
  • 距骨骨软骨损伤(osteochondral lesion of talus,OLT)系发生在距骨穹隆,累及软骨和软骨下骨的病变,是踝关节最常见的损伤之一。临床上可无症状,或者表现为脚踝疼痛,活动时加重,疼痛位置与OLT位置没有必然关系。OLT病情进展的危险因素直接影响临床治疗手段,危险因素包括MRI上损伤深度、关节软骨下囊肿形成、骨髓水肿程度[1]。通常采用Hepple等[2]改良的MRI分期标准如下,Ⅰ期:关节软骨损伤;ⅡA期:关节软骨损伤伴软骨下隐匿性骨折,MRI显示周围骨髓水肿;ⅡB期关节软骨损伤伴软骨下隐匿性骨折,不伴周围骨髓水肿;Ⅲ期骨软骨块分离,无移位;Ⅳ期骨软骨块分离,有移位;Ⅴ期关节软骨下囊肿形成。由于MRI分辨率较高,能显示软骨及软骨下骨髓水肿等改变,使MRI成为诊断OLT的最常用的影像手段。MRI上发现骨髓水肿,是早期诊断OLT和疗效评估的依据。但MRI检查时间长,层间距较厚,禁忌症多,并且对OLT骨质囊变及骨折的显示不如CT。双能CT(dual-energy CT,DECT)兼备常规CT的优势,不仅辐射剂量较常规CT小,更重要的是能显示脊柱及四肢骨的骨髓水肿[3]。DECT虚拟去钙(virtual non-calcium,VNCA)技术利用两种不同的X射线能谱采集两组数据集,使用三物质分离算法,经后处理去除钙元素,生成彩色编码的VNCA图像,可以显示异常的骨髓水肿,对异常骨髓进行定性及定量分析。Ⅰ期患者通常保守治疗就能恢复,但是ⅡA期患者需要定期复查,防止病情进展进展,必要时可早期干预,鉴于目前ⅡA期患者发病率较高,所以影像诊断ⅡA期对于OLT的临床转归非常重要[4]

    迄今为止尚无DECT应用于OLT的文献报道。本研究旨在探讨DECT对OLT及ⅡA期的诊断价值。

    本研究通过医院伦理委员会批准,所有纳入研究的患者均签署知情同意书。纳入标准:①临床上踝关节后足跟对齐情况、稳定性、运动范围及美国足踝骨科协会量表评分[5]符合OLT表现;②MRI图像有典型明确的OLT影像表现,并可以根据Hepple改良的MRI分期标准进行分级;③无踝关节手术史;④无急性外伤或踝关节骨折。

    根据上述纳入标准,纳入2023年1月至2023年12月河北省人民医院骨科接诊,经临床及MRI检查确诊为OLT的患者共30例,男14例,女16例,年龄18~70岁,平均年龄为(42±16)岁。所有纳入的患者均进行患侧踝关节MRI检查及双侧踝关节DECT检查,两种检查间隔时间在24 h内。

    所有患者均使用第3代双源双能CT(somatom Definition Force,Siemens Healthineers)进行扫描。该设备有两套X线球管,A球管:管电压80 kV,管电流150 mA;B球管:管电压Sn 150 kV,管电流100 mA,准直器0.6 mm,螺距0.7,重建层厚3.0 mm。使用自动管电流调制技术(CARE DOSE 4 D)。患者仰卧位,双脚跟并拢,足先进的方式,扫描范围自胫骨下段至跟骨下缘。一次DECT扫描后,得到80 kV,Sn 150 kV和0.5系数融合图,0.5系数融合图与单能120 kV的加权图像相近,可以作为常规CT分析使用。将其发送至工作站(Syngo Via DECT,VB10)进行处理。VNCA技术选择“Bone Marrow”后处理功能,形成VNCA彩色编码的图像。

    采用GE1.5 MRI(Signa Excitehdx;GE Healthcare),使用踝关节专用表面线圈,扫描范围同CT。包括的序列有:矢状位快速自旋回波T1 WI序列(TR580 ms,TE11.8 ms,FOV18×18 mm;矩阵288×224,层厚3.0 mm,层间距1.0 mm),冠状位脂肪抑制T2 WI序列(fat saturation T2 weighted image,FS-T2 WI),(TR 3560 ms,TE 68.5 ms,FOV17×17 mm;矩阵288×192,层厚3.0 mm,层间距1.0 mm),轴位T2 WI(TR 3240 ms,TE 63.0 ms,FOV15×15 mm;矩阵320×192,层厚4.0 mm,层间距1.0 mm)。

    为方便记录病变的区域及范围,将距骨穹隆表面划为九宫格分区[6]图1)。DECT三维重建,利用轴位的分区进行矢状位及冠状位的定位。MRI同样根据轴位,使用定位线对矢状位及冠状位进行病灶定位。采用Hepple等改良的MRI分期标准。为方便研究、比较,我们将阴性的区域,定为0期。

    图  1  距骨骨软骨的九宫格分区(上面观)
    Figure  1.  Nine-grid partitioning of the talar osteochondral surface (superior view)

    本研究由4名骨科经验丰富的放射科主治医生A、B、C和D,分别对MRI及DECT图像进行分期。A医生对30例MRI图像进行诊断及分期。B医生和C医生,在不知MRI结果的情况下,对0.5系数DECT融合图和VNCA图像进行视觉评估分期。DECT图像评估时,首先观察0.5系数融合图及其三维重建图像,对OLT进行Ⅰ、Ⅱ、Ⅳ、Ⅳ、Ⅴ的大体分期,再观察VNCA图像,把Ⅱ期分为ⅡA期和ⅡB期,有骨髓异常信号为ⅡA期,无骨髓异常信号为ⅡB期。在VNCA图像上,观察关节软骨下的骨髓,正常骨髓颜色为蓝紫色,异常的骨髓区域,表现为边缘模糊的绿色(图2)。

    图  2  患者女62岁,诊断为OLT
    Figure  2.  The patient is a 62 year-old female diagnosed with an osteochondral lesion of the talus

    D医生对照MRI的T2 WI序列,使用VNCA技术对ⅡA期相应病变区域进行定量评估。在VNCA图像上找到相应的异常区域,避开骨皮质下2 mm区域,手动画感兴趣区(region of interest,ROI),面积为0.2 cm2,同一区域进行至少两次测量,取平均CT值。在VNCA图像上找正常骨髓区域(同一患者同侧距骨),避开骨皮质下2 mm区域(减少骨皮质对病变的干扰),手动画ROI,面积为0.2 cm2,进行至少两次测量,取平均CT值。

    利用SPSS 26.0统计软件分析。以MRI结果为标准,分别评估医生B和医生CDECT分级结果与MRI分期结果的一致性,及两名医生之间DECT分期结果的一致性。当0.80<Kappa≤1时,表示两结果具有高度一致性;当0.60<Kappa≤0.80时,两结果一致性好;当0.40<Kappa≤0.60时,两结果具有中等一致性;当0.20<Kappa≤0.40时,表示两结果一致性尚可,当Kappa≤0.20时,两结果一致性差。

    以MRI为诊断标准,分别计算B医生和C医生的DECT分期结果的敏感性、特异性、准确性、阳性预测值(positive predictive value,PPV)、阴性预测值(negative predictive value,NPV)和一致性;两名医生DECT结果之间的一致性。B医生和C医生使用虚拟去钙技术视觉评估ⅡA的敏感性、特异性;对比MRI结果,B医生和C医生视觉评估ⅡA的一致性;两名医生之间的一致性。

    D医生在VNCA图像上ⅡA期病灶区测得的CT值及对照组CT值,进行正态性检验,若数据符合正态性分布,则对这组数据使用独立样本T检验,若数据不符合正态性分布,则使用Mann-Whitney U检验。使用受试者工作(receiver operating characteristic,ROC)曲线对这组数据进行分析,计算曲线下面积(areas under the curve,AUC),计算ⅡA期病变区与正常区骨髓CT值的最佳截断值,及此时的敏感性、特异性。

    总共收录30个踝关节,270个区域。

    A医生MRI评估结果如下,164个0期区域,5个Ⅰ期区域,89个ⅡA期区域,4个ⅡB期区域,5个Ⅲ期区域,2个Ⅳ期区域,1个Ⅴ期区域。

    B医生DECT评估结果如下,158个0期区域,0个Ⅰ期区域,85个ⅡA期区域,16个ⅡB期区域,5个Ⅲ期区域,2个Ⅳ期区域,4个Ⅴ期区域(表1)。

    表  1  B医生DECT分区结果与MRI结果计数
    Table  1.  Counts of dual energy computed tomography (DECT) staging results and magnetic resonance imaging (MRI) results performed by Doctor B
    分区 0 IⅤ ⅡA ⅡB DECT Total
    0 151 0 0 0 3 10 0 164
    5 0 0 0 0 0 0 5
    0 0 5 0 0 0 0 5
    0 0 0 2 0 0 0 2
    0 0 0 0 1 0 0 1
    ⅡA 2 0 0 0 0 75 12 89
    ⅡB 0 0 0 0 0 0 4 4
    MRI Total 158 0 5 2 4 85 16 270
    下载: 导出CSV 
    | 显示表格

    C医生DECT评估结果如下,158个0期区域,0个Ⅰ期区域,86个ⅡA期区域,15个ⅡB期区域,5个Ⅲ期区域,2个Ⅳ期区域,4个Ⅴ期区域(表2)。

    表  2  C医生DECT分区结果与MRI结果计数
    Table  2.  Counts of dual energy computed tomography (DECT) staging results and magnetic resonance imaging (MRI) results performed by Doctor C
    分区 0 ⅡA ⅡB DECT Total
    0 150 0 0 0 3 11 0 164
    5 0 0 0 0 0 0 5
    0 0 5 0 0 0 0 5
    0 0 0 2 0 0 0 2
    0 0 0 0 1 0 0 1
    ⅡA 3 0 0 0 0 75 11 89
    ⅡB 0 0 0 0 0 0 4 4
    MRI Total 158 0 5 2 4 86 15 270
    下载: 导出CSV 
    | 显示表格

    以MRI为参考标准,B医生和C医生运用DECT评估OLT结果的敏感性、特异性、准确性、阳性预测值、阴性预测值分别为84%,91%、89%、83%、90%和85%、89%、88%、83%、91%。B医生和C医生的DECT结果与MRI结果Kappa值分别为0.771和0.758;B医生和C医生的DECT结果Kappa值为0.886。

    对比MRI,B医生和C医生使用虚拟去钙技术视觉评估ⅡA的敏感性、特异性分别为85%、94%和84%、93%,对比MRI,B医生和C医生视觉评估ⅡA的Kappa值分别为0.807和0.801,B医生和C医生之间的Kappa值为0.889。

    在ⅡA期评估中,B医生和C医生的假阳性区域分别有10个和11个区域,其中区域并不完全相同。B医生假阴性区域有14个,其中12个区域因未发现骨髓异常,被诊断为ⅡB期,另2个区域,因未发现隐匿性骨折和骨髓异常,被诊断为0期;C医生假阴性14个,其中11个区域因未发现骨髓异常,被诊断为ⅡB期,另3个区域,因未发现隐匿性骨折和骨髓异常,被诊断为0期。

    以MRI为参考标准,总共有89个ⅡA期区域,D医生在VNCA图像上找出与T2 WI序列上相对应的骨髓水肿区域,测量得出89个异常CT值,对照组(在同一患者的同侧距骨上)测出89个正常骨髓区CT值。总共测出的178个CT值,经SPSS统计软件计算,病变区骨髓CT值(0.55±1.22)HU,对照组骨髓CT值(−48.30±1.24)HU(表3),病变区骨髓CT值与对照组CT值存在统计学差异(P<0.01)(图3)。病变区的CT值ROC曲线显示(图4),AUC值为0.987(95%置信区间:0.974−1.000),病变区骨髓CT值与对照组CT值的最佳截断值为−21.85 HU,此时的敏感性、特异性分别为92%和98.9%。

    表  3  在VNCA图像上,D医生测得的IIA期病变区CT值和对照组CT值
    Table  3.  Normal bone marrow computed tomography (CT) attenuation and Stage IIA lesion CT attenuation values measured on the virtual non-calcium images (VNCA) by Doctor D
    Normal bone marrow (none Edema) Stage IIA (with bone marrow edema) P
    CT value (0.55±1.22)HU (−48.30±1.24)HU <0.01
    下载: 导出CSV 
    | 显示表格
    图  3  D医生在VNCA图像上测得IIA期病灶区CT值与对照组CT值
    Figure  3.  The computed tomography (CT) attenuation values of Stage IIA lesion area and the normal bone marrow CT attenuation values on virtual non-calcium (VNCA) images performed by Doctor D
    图  4  D医生测量统计定量诊断IIA 的ROC曲线
    Figure  4.  Region under the curve (ROC) plot of the diagnostic value of dual energy computed tomography virtual non-calcium images for Stage IIA osteochondral lesion of the talus measured by Doctor D

    OLT主要影响距骨穹隆的软骨及软骨下骨,其病因多样,因人群而异[7]。儿童和年轻人中,病因包括局部缺血、次级关节下骺板异常软骨内骨化、重复性微创伤及遗传倾向,常表现为剥脱性骨软骨炎,特征是软骨退变与软骨下骨骨质分离,被视为非创伤性特发性现象。成年人中,OLT可归因于外伤、内分泌或代谢异常、维生素D缺乏及退行性关节疾病[8],其中外伤最为常见。外伤性距骨骨软骨损伤具有特定规律[9]:前外侧区域损伤通常由踝关节内翻和背伸暴力引起,形成浅而圆片状的损伤;后内侧区域损伤则因反复内翻、跖屈和外旋暴力所致,形成深而杯形的损伤。

    OLT的病理改变涉及距骨穹窿的软骨下骨[10]。外伤等因素可导致微骨折和骨挫伤,愈合不良后,液体间歇性地渗入软骨下骨,产生压力,引发骨坏死和骨吸收,形成溶解性病变和骨软骨碎片。液体压力减少时,骨吸收停止,周围发生骨重塑和过度成骨反应,导致修复困难[11]。软骨下骨板的损伤对软骨代谢至关重要,其退化会导致蛋白聚糖和糖蛋白流失,加剧软骨受损[13]。因此,早期检测软骨下骨板损伤对OLT的干预至关重要[14]。由于MRI的T2 WI序列能显示因液体压力导致的骨吸收、骨溶解和骨囊变的高信号[12],因此MRI为本病的主要影像检查手段。目前有关本病的MRI报道较多,而DECT用于OLT诊断迄今尚未见文献报道。

    常规CT使用多能谱射线,会产生射线硬化现象[15],导致物质真实的衰减系数与CT多能谱射线的衰减只是近似相等。相比之下,双能量CT(DECT)采用单一能谱的单色射线[16],其光子能量相同。DECT的虚拟非钙成分分析(VNCA)技术通过三物质分离技术[17],能分解每个体素的衰减为钙含量和虚拟去钙含量,生成钙图和VNCA图。VNCA图以彩色编码直接显示骨髓颜色变化,蓝紫色代表正常黄骨髓,绿色表示骨髓水肿或炎症[18]。在评估非创伤性骨髓水肿时,DECT使用50 HU截止值进行颜色编码图像可视化[19],有助于区分轻度和重度骨髓水肿[20],并通过调整叠加级别和阈值获得更清晰显示[21]

    文献[22]指出DECT在脊柱及四肢创伤性、非创伤性骨髓水肿及关节炎性病变诊断方面呈现出较高的应用价值。Foti等[23]等的综述显示,DECT对急性压缩骨折患者的急性骨髓水肿检查具有高度的敏感性(86.2%)、特异性(91.2%)和准确性(89.3%)。Wang等[24]研究认为DECT在膝关节和踝关节的骨软骨损伤诊断中表现非凡。对于创伤性及非创伤性损伤,尤其是骨关节炎伴疼痛时出现的典型骨髓水肿,DECT通过虚拟非钙成分分析(VNCA)技术能够清晰观察到软骨下不均匀、边界模糊的骨髓水肿[25]。尽管软骨下骨硬化可能导致一定的误诊或漏诊[26],但结合关节间隙变窄、关节炎、韧带及半月板损伤等影像学特征,有效的提高了DECT的诊断准确性。Jans等[27]的研究表明,VNCA技术在诊断外伤引起的距骨创伤性骨髓水肿方面,无论是定性(敏感性97.4%、特异性 86.9%、PPV88.2%、NPV97.1%、准确性95.5%)还是定量(敏感性98.00%、特异性90.31%、PPV91.00%、NPV92.31%和准确性96.83%)分析,均呈现出高度的敏感性、特异性和准确性。此外,也有文献报道,DECT在检测软骨下骨折及骨皮质受累方面较MRI更为准确[28],因其能较好的显示关节软骨下骨的小囊变、早期骨质硬化、坍塌骨质周围的骨髓水肿,从而有助于关节骨软骨损伤的分期评估[29]

    本研究结果显示,在OLT的ⅡB期、Ⅲ期、Ⅳ期、Ⅴ期的诊断中,DECT的诊断效能与MRI基本相仿。值得关注的是,在CT诊断的Ⅴ期病例中有3例MRI漏诊。笔者体会这可能与距骨关节面下囊性灶较小(直径均小于1.5 mm),常规CT对骨质的细小病灶显示及测量较扫描层厚较厚的MRI图像更具优势有关,此点与文献[30-31]报道相符。尽管本研究上述四期病例的样本量相对较少,但仍能说明DECT对OLT的诊断价值不容小觑。

    本研究结果还显示,对于OLT的ⅡA期,两名医生主观评估的敏感性、特异性分别为85%、94%和84%、93%,两名医生DECT评估结果对比MRI的Kappa值分别为0.807和0.801,两名医生之间的Kappa值为0.889,与Ren等[32]研究结果基本相符,而在诊断敏感性方面与longo[33]、何绪成等[34]研究结果相比较略低。我们认为,这与本研究纳入的OLT患者骨髓损伤程度较轻,病变范围相对较小,以及OLT的异常骨髓密度位于软骨下区域,易受到关节腔和关节面下骨质硬化的干扰[35],导致VNCA图像编码颜色发生变化,从而影响了DECT的检测效果有关。

    关于本研究ⅡA期诊断出现的假阳性(B医生约11.8%、C医生约12.8%)及假阴性(B医生约15.7%、C医生约15.7%)现象,同样值得关注。笔者分析前者可能与以下因素有关:①年轻患者的距骨可能含有较多不均匀分布的红骨髓,导致VNCA图像呈现相对高密度;②距骨穹隆的骨质硬化也可能使VNCA图像呈现高密度,进而引发假阳性。因此,在评估过程中,先查看DECT的0.5系数融合图以了解骨硬化部位,有助于减少误诊风险。后者形成的原因可能为:①异常骨髓病变范围较小,程度较轻,VNCA上未能显示。②轻度病变与正常骨髓颜色差距小,不同阅读者在识别时可能会有差异,在DECT 0.5系数融合图上,未发现阴性骨折。③患者年龄偏大,距骨骨皮质及其下方骨质有不同程度的骨质疏松、密度较低,导致特别轻微的骨小梁断裂未被发现而漏诊[36]

    本研究结果尚显示,OLTⅡA期骨髓异常区与正常骨髓区CT值具有显著统计学差异,前者CT值明显高于后者,最佳截断值为−21.85 HU,其敏感性、特异性分别为92%和98.9%,与Foti等[37]研究结果(截断值为−20 HU,敏感性88%,特异性86.6%)相仿。表明CT定量检测对OLTⅡA期骨髓水肿的诊断具有重要的佐证意义。然而,由于设备、扫描参数、检测位点、受检者年龄等因素影响[38],有研究[37-38]显示最佳截断CT值存在较大差异,需要在实际工作中予以甄别。

    本研究具有以下局限性:①所收集的病例以轻症患者为主,除ⅡA期外,其他四期的病例样本数偏少,未来需要收集更多其他各期病例,以更好的印证DECT对其他各期的诊断价值;②DECT对Ⅰ期仅软骨损伤的病例观察受限。由于VNCA技术不能很好的显示关节软骨,本研究5例Ⅰ期患者均出现假阴性结果。笔者赞同其原因可能与踝关节间隙较窄,关节软骨较薄有关[39]。期待通过优化检查方法,通过轴向牵引踝关节并行CT检查,以增宽关节间隙,再经特定软件处理及颜色编码,更好的显示关节软骨[40],从而使OLTⅠ期患者得到及时诊断与治疗。③本研究侧重于OLT的DECT分期及ⅡA期的诊断,以MRI作为评估骨髓水肿的金标准并与其进行对照分析,但MRI在OLT尤其是在Ⅰ期诊断的准确性并非100%,未来需要记录关节镜及手术结果加以对照。④本研究中使用的VNCA算法只与相同的供应商的特定后处理软件兼容,是否与其他制造商的DECT系统兼容尚未可知。

    综上研究表明,相较于MRI检查,DECT在OLT的诊断及分期上具备可行性。借助VNCA技术,能够识别OLT区域中的骨髓水肿,并对ⅡA期进行准确、量化的诊断评估,呈现出良好的诊断效能。然而,DECT在Ⅰ期的诊断上表现欠佳。本研究仅为初步探索,未来还需深入研究。期待DECT在OLT诊断领域为临床提供更多有价值的信息。

  • 图  1   初诊IgG4-SC患者MRCP分型表现

    (a)~(d)分别显示Ⅰ~Ⅳ型IgG4-SC。(a)图为Ⅰ型,胆总管下段狭窄(箭),其上游肝内外胆管扩张。(b)图为Ⅱa型,胆总管下段及肝内胆管多发狭窄(箭),狭窄上游肝内外胆管扩张。(c)图为Ⅲ型,胆总管下段和肝门部胆管狭窄(箭),其上游胆管扩张。(d)图为Ⅳ型,肝门部胆管狭窄(箭),肝内胆管梗阻性扩张。

    Figure  1.   MRCP classifications of IgG4-SC in newly diagnosed patients

    图  2   初诊IgG4-SC患者MRCP狭窄端及狭窄段形态

    (a)图显示肝外胆管狭窄端呈漏斗状(箭),狭窄段较长且管腔断续可见。(b)图显示狭窄端呈截断状,狭窄段管腔不可见(箭)。(c)图显示肝外胆管胰上段狭窄,管腔粗细不均(箭)。(d)图显示肝外胆管胰腺段狭窄伴邻近十二指肠侧憩室样外凸(箭)。

    Figure  2.   Morphologic patterns of the stenotic end and segment of IgG4-SC in newly diagnosed patients on MRCP

    图  3   51岁,男性,初诊IgG4-SC患者增强MRI表现

    (a)~(d)分别为轴面T1WI的蒙片、动脉期、门静脉期、延迟期图像,可见肝外胆管壁均匀向心性增厚及渐进性强化(箭),同时见胆囊壁增厚及异常强化。(e)为肝内胆管层面的轴面T1WI延迟期,(f)为冠状面T1WI延迟期,可见肝内、外胆管壁弥漫性增厚及明显强化(箭),肝内胆管扩张。

    Figure  3.   Contrast-enhanced MRI findings of IgG4-SC in a newly diagnosed 51-year-old male patient

    表  1   IgG4-SC患者血清IgG4、IgG升高与影像表现的相关性分析

    Table  1   Correlation analysis between elevated serum IgG4 and IgG levels and imaging findings in patients with IgG4-SC

    影像表现血清IgG4升高血清IgG升高
    rPrP
    肝外胆管狭窄段长度  -0.3480.070-0.0860.717
    管壁厚度MRI测量   0.2080.2710.2090.363
    管壁厚度CT测量    0.2470.4160.6550.078
    合并其他IgG4-RD的数量0.613*0.0000.524*0.003
     注:*为P<0.01,相关性显著。
    下载: 导出CSV
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出版历程
  • 收稿日期:  2022-08-04
  • 修回日期:  2022-09-11
  • 录用日期:  2022-09-12
  • 网络出版日期:  2022-09-27
  • 发布日期:  2023-03-30

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