胆管内乳头状肿瘤的动态增强CT表现

Dynamic contrast-enhanced CT appearances of the intraductal papillary neoplasms of the bile duct

目的探讨胆管内乳头状肿瘤CT动态增强的表现及其病理基础。方法回顾性分析16例经手术病理证实的胆管内乳头状肿瘤患者资料，所有患者术前均行CT平扫及动态增强扫描，分析其CT征象并与手术病理对照。其中12例共38个病灶（非癌变组4例17个病灶、癌变组8例21个病灶）可清晰显示，测量各扫描期肿瘤的CT值及平扫胆管内胆汁的CT值。搜集近期行腹部CT检查表现正常的40名受检者作为正常对照组和40例胆结石患者作为胆石症组，测量其平扫胆管内胆汁的CT值，用于和胆管内乳头状肿瘤比较。非癌变和癌变胆管内乳头状肿瘤组织各期相CT值比较采用独立样本￡检验，远端胆管扩张情况的比较采用Fisher确切概率法，和正常对照组及胆石症患者的平扫胆汁CT值比较采用秩和检验。结果16例中，肿瘤位于肝左叶者8例，肝右叶者1例，左、右叶均受累者1例，肝门部1例，胆总管3例，肝右叶及胆总管均受累者2例。胆管内肿瘤呈乳头状11例、扁平状3例，两种形态并存者1例，1例CT未发现明确肿瘤组织，仅见胆道系统扩张和胆管结石。非癌变胆管内乳头状肿瘤平扫、动脉期、门静脉期CT值分别为（25．8±8．0）、（37．7±10．3）和（51．7±17．1）HU，癌变胆管内乳头状肿瘤CT值分别为（38．4±10．2）、（56．6±18．0）和（68．4±13．4）HU，癌变肿瘤CT值高于非癌变肿瘤，差异均有统计学意义（t值分别为-3．510、-3．549和-3．767，P值均〈0．01）。胆管内乳头状肿瘤患者平扫胆汁CT值（中位值为5．8HU）高于正常对照组（中位值为0．4HU）和胆管结石患者（中位值为2．4HU），差异均有统计学意义（Z值分别为3．854和2．765，P值均〈0．01）。16例均见肿瘤近端胆管扩张，11例合并远端胆管扩张，癌变肿瘤远端胆管扩张〉100％者7例，多于非癌变组2例，但差异无统计学意义（P〉0．05）。6例合并结石，其中3例结石位于病变区域，3例结石距病变部位较远。结论胆管内乳头状肿瘤常见于肝左叶，多呈乳头状；CT平扫肿瘤密度偏低，动态增强后呈轻、中度进行性延迟强化，癌变的肿瘤组织CT值高于未癌变者；肿瘤近、远端胆管均可扩张；胆汁的CT值比正常人及胆结石患者稍高；可合并肿瘤区域或非肿瘤区域的胆管结石。

Objective To analyze the dynamic contrast-enhanced CT appearances of intraductal papillary neoplasms of the bile duct and improve its diagnostic accuracy. Methods Sixteen patients with intraductal papillary neoplasms of the bile duct confirmed histopathologically after surgical operation underwent dynamic contrast-enhanced multi-detector row CT scans. All imaging data were reviewed and analyzed retrospectively in correlation with surgical and pathological findings. CT values of 38 well-visualized lesions in 12 of the 16 patients at the pre-contrast phase, arterial phase and venous phase were measured. Four of the 12 patients with 17 lesions had benign tumors, and 8 of the 12 patients with 21 lesions had malignant tumors. Comparisons of CT values at the three phases between the two groups were carried out using independent sample t test. The bile CT values were measured in these 12 cases,40 normal volunteers, and 40 subjects with bile duct stones, and the Wilcoxon signed-rank test was applied to compare the bile CTvalues between tumor group and the normal group and between tumor group and the bile duct stone group. The diameters of the bile ducts proximal to and distal to tumors were also measured, and Fisher exact method was carried to analyze the data. Results Lesions located at the left lobe in 8 out of the 16 patients, the right lobe in 1 case, both the left and right lobes in 1 case, the hepatic hilum in 1 case,the common bile duct in 3 cases, and both the right lobe and the common bile duct in 2 cases. Eleven lesions appeared as papillary masses,3 as flat masses, 1 as mixed papillary and flat masses. In one case, tumor mass could not be definitely visualized, and only dilated bile ducts and stones were demonstraled. The mean CT values of the benign tumors were （25.8 ±8.0）, （37.7 ±10. 3 ） and （51.7± 17. 1 ） HU respectively at pre-contrast phase,arterial phase,and venous phase,and the malignant tumors were （38. 4 ± 10. 2）, （56. 6 ± 18. 0） and （68.4 ± 13.4） HU respectively. The CT values of malignant tumors were higher than the benign tumors at all three phases（t = - 3. 510, - 3. 549 and - 3. 767,P 〈 0. 01 ）. The median bile CT value was 5.8 HU in intraductal papillary neoplasms ,0. 4 HU in the normal control group, and 2. 4 HU in the group with bile duct stones, the median CT value of tumor group was higher than either the normal group or the group with bile duct stones （Z = 3. 854 and 2. 765,P 〈0. 01 ）. All the patients showed proximal bile ducts dilatation,and 11 patients exhibited additional distal bile ducts dilatation. Proximal bile duct dilatation of more than 100% was seen in 7 cases in the malignant group, whereas only 2 patients in the benign group, but there was no significant difference （ P 〉 0. 05 ）. Bile duct stones were noted in six cases, three at the tumor area, and the remaining three away from tumor. Conclusions Intraductal papillary neoplasms of the bile duct involve the left lobe more frequently. At pre-contrast CT, the tumor density is low. On dynamic contrast-enhanced CT, tumors show mild to moderate enhancement with gradual delayed enhancement. Malignant tumors show higher CT values than benign ones. Both proximal and distal bile ducts may be dilated. The CT values of the bile in the tumor group are mildly higher than either the normal control group or the group with bile duct stones. Bile duct stones can be noted at or away from the tumor area.