含气腔型浸润性肺小腺癌的CT表现与病理分型的对照研究

A comparative analysis of CT features and pathological types of small lung invasive adenocarcinoma with air-containing space

目的探讨含气腔型浸润性肺小腺癌的CT表现及其与病理分型之间的关系,同时探讨气腔形成的可能机制。方法回顾性分析2012年1月至2017年12月经温州医科大学附属第一医院手术病理证实的50例含气腔型浸润性肺小腺癌患者的影像和病理资料,CT图像分析包括肿瘤及其气腔的影像学特征,病理切片分析包括肿瘤病理亚型及分化程度。肿瘤及气腔CT征象与病理分型之间的比较采用χ^2检验或Fisher确切概率法;结节大小、空泡最大径等计量资料的差异性比较采用方差分析(正态分布)或Kruskal-Wallis秩和检验(非正态分布)。采用Spearman秩相关分析结节密度与病理亚型及分化程度之间的相关性。结果(1)肿瘤CT表现:肿瘤以周围型病变(46/50)多见,多表现为亚实性结节(37/50),瘤-肺界面常清晰(46/50)。肿瘤常伴有分叶征(37/50)、毛刺征(27/50)、空气支气管征(43/50)、胸膜凹陷征(36/50)等恶性征象。结节长短径均值范围7.50~18.12 mm,平均(12.91±2.85)mm。结节密度CT值范围-657.00~73.00 HU,平均(-213.88±206.16)HU。(2)气腔CT表现:气腔以单发(37/50)多见,且以偏心(29/37)分布为主;气腔最大径范围1.00~16.00 mm,平均为(4.23±3.14)mm;≤5 mm气腔35例(70%),>5 mm气腔15例(30%)。(3)CT表现与病理分型对照分析:结节密度、气腔个数、结节密度类型在不同病理亚型中的差异有统计学意义(P<0.05),其中结节密度与病理亚型呈正相关(r=0.371,P=0.008)。结节密度、结节短径、结节密度类型、毛刺征、胸膜凹陷征在肿瘤不同分化程度间的差异有统计学意义(P<0.05),结节密度与肿瘤分化程度呈负相关(r=-0.451,P=0.001)。结论浸润性肺小腺癌中含气腔型检出率为12.7%,多表现为周围型亚实性结节,其CT表现与病理分型之间存在一定的相关性;气腔形成的可能机制为单向活瓣引起的远端支气管扩张,肿瘤破坏肺泡结构所致。

Objective To evaluate the CT features of small lung invasive adenocarcinoma with air-containing space and its relationship with pathological types, and to explore the pathological basis of air-containing space. Methods CT and pathological data of fifty patients with surgically proven lung invasive adenocarcinoma with air-containing space in our hospital from January 2012 to December 2017 were retrospectively reviewed. CT image analysis included image features of tumor and air-containing space. Pathological analysis included pathological subtype, differentiation degree. CT features of tumor and air-containing space were compared with regard to pathological types using chi-square test or Fisher exact text. Analysis of variance was used to compare quantitative data satisfying normal distribution, while those data not satisfying normal distribution were compared with Kruskal-Wallis test. In addition, Spearman correlation was used to analyze the correlation between nodule density and pathological types. Results (1) CT features of tumors: Tumors were predominantly located in peripheral lungs (46/50). Most of the tumors were subsolid nodules (37/50). Tumor-lung interface was generally clear (46/50). Tumors are often accompanied by malignant signs such as lobulation (37/50), spicule sign (27/50), air bronchogram sign (43/50), and pleural indentation (36/50). The mean diameter of nodules ranged from 7.50 mm to 18.12 mm, with an average of (12.91±2.85)mm. The nodule density ranged from-657.00 to 73.00 HU with an average of (-213.88±206.16) HU.(2) CT features of air-containing space: Air-containing spaces were commonly solitary (37/50) and were found to be mainly in an eccentric distribution (29/37). The maximum diameter of air-containing space ranged from 1.00 to 16.00mm, and the average diameter was (4.23±3.14)mm. Air-containing spaces less than 5mm were found in 35 cases (70%), and air-containing spaces more than 5mm were found in 15 cases.(3) Comparison of CT features and corresponding pathological types: Nodule density, number of air-containing space, and type of nodule density in different pathological types were statistically different (P<0.05). There was a correlation between nodule density and pathological subtypes (r=0.371, P=0.008). Differences of nodule density, short-dimension of nodule, type of nodule density, spicule sign, pleural indentation among different tumor differentiation degrees were significant (P<0.05). The degree of tumor differentiation was negatively correlated with nodule density (r=-0.451, P=0.001). Conclusion The detection rate of air-containing space in lung invasive adenocarcinomas is 12.7%. Most small lung invasive adenocarcinomas with air-containing space are presented as peripheral subsolid nodule, and there is a certain correlation between their CT features and pathological types. The pathological basis of air-containing space was supposed to be dilated distal bronchiole induced by check-valve mechanism and destruction of alveolar structure by tumor.