共查询到20条相似文献,搜索用时 15 毫秒
1.
背景与目的:肺癌是目前发病率和死亡率较高的恶性肿瘤,其预后很大程度上取决于早期诊断和治疗,而放射影像学如X线平片和CT是发现和诊断肺癌最重要的手段之一.但是对于30mm以内肺周围孤立结节(solitary puhnonary nodules.SPN)的诊断较难.尤其对10mm以内SPN的影像诊断更难。本研究拟对CT影像学10mm以内SPN进行分析总结。方法:对CT影像学上直径〈10mm且最终通过各种方法获得病理学证据的102例SPN进行分析。比较良恶性病变的差异,总结小结节肺癌的影像学特征。结果:肺内〈10mm的SPN中,以良性病变为主,占64.7%。分别是炎性假瘤、良性肿瘤、结核等;原发性肺癌占24.5%,其中分期较晚肺癌(ⅡA期及以上)占5.9%,影像学上可藉边缘不齐、有毛刺衙、气管和血管受累、强化值羞异等特点与良性病变鉴别;肺转移癌占10.8%,其影像学表现与原发性肺癌相似,结论:肺内〈10mm的SPN中。以良性肿瘤为主。其次为肺癌。 相似文献
2.
98例肺部单发小结节的临床分析 总被引:2,自引:0,他引:2
目的:研究肺部单发小结节良恶性患者的临床表现和胸部CT特点。方法:分析98例肺部单发小结节患者的资料,对其临床表现和胸部CT特点进行数据资料统计,采用卡方分析,两组率的差异采用两组率比较的方法。结果:98例患者中,肺癌46例(46.9%),良性肿瘤14例(14.3%),结核球38例(38.8%),无任何症状查体发现小结节和仅伴有咳嗽咯痰症状者56例(57.1%),其中50%为I期肺癌患者。年轻,有长期发热、盗汗,胸背痛症状者提示结核;无任何症状、仅有咳嗽咳痰,痰中带血或咯血提示恶性肿瘤;胸部CT影像中良性肿瘤发生于中叶或舌叶的比率高(42.3%),结节边界清,密度均匀,恶性肿瘤多边界不清,密度不均,有毛刺,分叶,胸膜皱缩;结核出现于下叶的比率高,钙化多见。结论:加强肺癌高危人群的普查,筛查和监测是发现早期肺癌患者的途径,对发现的肺部小结节,结合临床表现和CT特点可以作出初步诊断,当结节直径>1cm,且不能判定良恶性时,可考虑手术探查。 相似文献
3.
15?mm以下周围型小肺癌的影像学检出和诊断 总被引:13,自引:0,他引:13
目的 评价胸部平片、常规CT(CCT)、螺旋CT(SCT)和高分辨率CT(HRCT)等各种影像学手段对15mm以下周围型小肺癌的检出和诊断能力。方法 回顾性分析59例经手术病理证实的15mm以下周围型小肺癌的临床表现及胸部平片、CCT、SCT和HRCT等的检查结果。因咳唔、咯血等症状就医发现5例,由健康体检发现37例,因其他疾病检查发现17例。病理Ⅰ期53例,Ⅱ期以上6例。结果 胸部平片的假阴性诊断率为47.5%,CCT的假阴性诊断率为17.6%,只有SCT可以检出全部病例而未发生漏诊。HRCT在显示肿瘤密度和各种征象细节的能力和准确性方面均优于胸部平片和CCT。15mm以下周围型小肺癌在HRCT征象方面与较大肺癌比较有明显差别。结论 SCT、HRCT是检出和诊断15mm以下周围型小肺癌的最佳影像学手段。应当提倡CT引导下的经皮肺穿刺活检技术。 相似文献
4.
肺癌胸膜种植转移的CT表现及其解剖分布 总被引:2,自引:0,他引:2
目的 总结胸膜种植转移的CT征象及其解剖分布。方法 回顾分析32例临床、病理确诊为原发性肺癌伴胸膜种植转移患者的CT表现。结果 本组患者的胸部CT征象主要表现为胸腔积液(24例)、脏层胸膜转移结节(10例)、壁层胸膜转移结节(16例)及胸膜增厚(3l例)。脏层胸膜转移结节中,分布于肺表面脏层胸膜9处,叶间胸膜l0处。壁层胸膜转移结节分布在膈胸膜、肋胸膜、纵隔胸膜、肺韧带,共45处。结节小至2—5mm的粟粒,大至5~10mm。胸膜增厚中因直接侵犯造成者10例,间接转移者2l例,后者中9例表现为增厚≤10mm,4例一侧胸膜环状增厚,5例纵隔胸膜增厚,3例肺韧带增厚。结论 肺癌胸膜转移最常见的CT征象为胸腔积液,其次为胸膜转移结节及胸膜增厚。转移结节最常分布在隔胸膜、肋胸膜,并可转移至肺韧带;早期表现为粟粒状,在肺窗容易发现。 相似文献
5.
Sugano M Shimizu K Nakano T Kakegawa S Miyamae Y Kaira K Araki T Kamiyoshihara M Kawashima O Takeyoshi I 《Oncology reports》2011,26(5):1205-1211
We examined the correlation between computed tomography (CT) findings and the incidence of epidermal growth factor receptor (EGFR) and KRAS mutations in lung adenocarcinoma. We analyzed the tumors of 136 patients with surgically resected primary lung adenocarcinoma. CT scans were evaluated for the presence of ground grass opacity (GGO), spiculation and the maximum diameter of the tumor was measured. SMart Amplification Process (ver. 2) was used to detect the presence of EGFR and KRAS mutations. EGFR and KRAS mutations were found in 56 (41.1%) and 25 (18.4%) of the 136 cases, respectively. Although no significant association was found between GGO and EGFR mutations (p=0.07), the EGFR mutation occurred more frequently in male patients with GGO than in those without GGO (p=0.04). The KRAS mutation occurred more frequently in patients whose tumor diameter was ≥ 31 mm than in those whose tumor diameter was <30 mm (p=0.003). Evaluation of CT findings may be helpful for determining the presence of EGFR and KRAS mutations, particularly when it is not possible to obtain a tumor specimen. 相似文献
6.
背景与目的:亚实性肺结节(subsolid pulmonary nodule,SSPN)作为一种特征性而非特异性的肺部病灶与早期肺癌关系密切,为探讨其对ⅠA期肺癌的诊断价值,本研究将分析不同性质SSPNs的CT诊断及鉴别诊断要点。方法:收集2008年4月—2014年4月在复旦大学附属肿瘤医院行CT引导Hookwire定位下胸腔镜手术(video assisted thoracic surgery,VATS)治疗的405例孤立性肺结节(solitary pulmonary nodule,SPN)患者的临床及影像学资料。根据磨玻璃影(ground-glass opacity,GGO)成分含量将SPNs分为单纯型磨玻璃影(pure ground-glass opacity,pGGO)、混合型磨玻璃影(mixed ground-glass opacity,mGGO)和实性结节(solid nodule,SN)3组,并统计各组恶性率。根据术后病理结果,再将SSPNs分为ⅠA期肺癌组和良性组,分析对比影响SSPN良、恶性的影像学特征。结果:共纳入405例SPN患者,其中SSPNs有367例(包括124例pGGOs和243例mGGOs),且在ⅠA期肺癌中的发生率明显高于良性组[95.9%(257/268) vs 80.3%(110/137),P<0.001]。SSPN的总恶性率为70.0%(257/367),且mGGO的恶性率(72.0%)要高于pGGO(66.1%)和SN(28.9%)。恶性SSPN多发生于中年女性肺上叶,且病灶边界不清、边缘毛刺、分叶和胸膜凹陷征的发生率高于良性组(P<0.05)。结论:SSPN是肺癌的重要征象,且以mGGO的恶性倾向最高。若中年女性伴有肺上叶的SSPN,且病灶边界不清、边缘出现毛刺、分叶或胸膜凹陷时,应高度怀疑恶性。 相似文献
7.
YuchengHan YueYuan JianguoChu 《中国肿瘤临床(英文版)》2004,1(2):96-100
OBJECTIVE To assess the value of chest X-ray film, conventional CT (CCT), Spiral CT (SCT) and high resolution CT (HRCT) for detection and diagnosis of small peripheral lung cancers less than 15 mm in diameter. METHODS Chest X-ray film, CCT, SCT and HRCT were taken in 59 cases of peripheral lung cancers less than 15 mm in diameter confirmed by pathological examination following an operation. The value of these procedures for diagnosis was analyzed retrospectively. RESULTS In 47% of chest X-ray films and 17% of CCT, small lung cancers were not detected. However no tumor escaped detection by SCT. HRCT was superior for showing density and detailed image signs compared to chest films and CCT. The HRCT features of small peripheral lung cancers were quite different from those of larger peripheral lung cancers. CONCLUSION The SCT is the best method for detection, and HRCT for diagnosis of small peripheral lung cancers less than 15 mm in diameter. CT guided percutaneous transthoracic needle biopsy should be advocated. 相似文献
8.
目的探讨低剂量螺旋CT联合肿瘤标志物癌胚抗原(CEA),鳞状上皮细胞癌相关抗原(SCC-Ag),胃泌素释放肽前体(ProGRP),神经特异性烯醇化酶(NSE)对良恶性孤立性肺结节的鉴别诊断价值。方法回顾性分析孤立性肺结节患者420例的临床资料,患者均有完整的低剂量螺旋CT及肿瘤标志物CEA、SCC-Ag、ProGRP、NSE检查结果和病理结果,以病理结果为金标准确定结节性质,比较良、恶性孤立性肺结节患者的低剂量螺旋CT的结节显示情况及肿瘤标志物CEA、SCC-Ag、ProGRP、NSE水平,比较低剂量螺旋CT和肿瘤标志物CEA、SCC-Ag、ProGRP、NSE单独检查及联合检查对良、恶性孤立性肺结节的检出率。结果病理结果提示420例孤立性肺结节患者中,良性287例,恶性133例。低剂量螺旋CT检查显示:良、恶性患者的结节直径、类型、结节形态、结节与肺的交界面、结节的边缘特征比较,差异均有统计学意义(P<0.05)。肿瘤标志物检查显示良性患者的血清CEA、SCC-Ag、ProGRP、NSE水平均显著低于恶性患者(P<0.05)。低剂量螺旋CT和肿瘤标志物联合检查对良、恶性孤立性肺结节的检出率均显著高于单独检查(P<0.05)。结论低剂量螺旋CT联合肿瘤标志物CEA、SCC-Ag、ProGRP、NSE对良恶性孤立性肺结节检出率高,并且对良、恶性结节具有鉴别诊断价值,可以为临床诊治工作提供指导信息。 相似文献
9.
目的探讨多层螺旋CT对同时多原发肺癌的诊断价值及其误诊原因。方法回顾性分析40例83个病灶同时多原发肺癌的CT征象及组织病理类型;分析X线胸片及CT漏误诊病变原因。结果同时多原发肺癌同侧肺发病率高于双侧肺(34∶6),周围型多见,占94%。组织学类型以腺癌最多见,占79.5%(66/83),腺癌中以女性发病更多见(55.2%)。周围型病灶边缘见毛刺者占76.9%(60/78),胸膜牵拉者占70.5%(55/78)。腺癌组和非腺癌组病灶的密度(非实性结节、部分实性结节、实性结节)、结节形态(圆形或类圆形、不规则形)、边缘分叶差异有统计学意义(P值均0.05)。CT第一诊断非恶性病灶共12个,术后均为腺癌,其中4个病灶随访3~6个月后复查,病灶增大,经手术病理证实。X线胸片漏诊周围型病灶24个(22个直径≤1.5cm;12个为非实性结节),均由胸部CT扫描检出。结论同时多原发肺癌不同癌灶大多具有原发肺癌的典型CT表现,并与其病理类型有一定关系。X线胸片漏诊率高,多层螺旋CT对检出小癌灶和非实性癌灶尤为重要。初次影像表现恶性征象不典型病灶,密切随诊非常重要。 相似文献
10.
For the early diagnosis of metastatic brain tumor, careful and long-term follow-up is important when the primary tumor has already been found. Metastatic brain tumor should be suspected whenever neurological symptoms develop in such a patient. In the cases of lung cancer or lung metastases, CT scan of brain should be taken even if the patients have no neurological symptoms, because lung cancer frequently metastasizes to the brain and other cancers metastasize to the brain via the lung. When the primary sites are unknown, primary brain tumors should be distinguished. Relatively rapid progression of symptoms including mental disturbance, multiple lesions on CT scan, lesions on chest X ray film, careful cerebral angiogram and MRI are helpful for the differential diagnosis. 相似文献
11.
目的:观察肺磨玻璃结节(GGN)的胸部CT征象,分析其在结节良恶性诊断中的价值。方法:回顾性分析2019年1月至2019年9月解放军总医院收治的65例具有GGN的CT影像征象的患者,根据病理结果分为良性组(26例)、恶性组(39例),收集整理相关临床及影像资料,分析良、恶性GGN不同CT影像特点及诊断价值。结果:良、恶性肺GGN在病变直径、形状、边界、分叶征、毛刺征、空泡征、支气管充气征、血管集束征、胸膜凹陷征和密度具有差异,差异有统计学意义(P<0.05)。 其中胸膜凹陷征的诊断灵敏度和特异度最高,分别为76.92%和73.08%;而粗糙边界的诊断灵敏度和特异度最低,分别为25.64%和26.92%。分叶征、胸膜凹陷征的AUC值分别为0.718、0.75,对恶性GGN有较高的预测价值。结论:肺GGN的胸部CT征象(病变直径、形状、边界、分叶征、毛刺征、空泡征、支气管充气征、血管集束征、胸膜凹陷征、密度)有助于鉴别诊断良、恶性肺GGN。 相似文献
12.
Boni G Bellina CR Grosso M Lucchi M Manca G Ambrogi MC Volterrani D Menconi G Melfi FM Gonfiotti A Davini F Angeletti CA Bianchi R Chella A 《Tumori》2000,86(4):364-366
Video-assisted thoracic surgery (VATS) is an interesting and emerging procedure for the diagnosis and treatment of peripheral pulmonary nodules. We developed a new radioguided surgical technique for the detection during VATS of pulmonary nodules smaller than 2 cm, situated deep in the lung parenchyma and neither visible nor palpable with endoscopic instruments. The procedure is divided into two phases. Two hours before surgery 0.3 ml of a solution composed of 0.2 mL of 99mTc-labeled human serum albumin microspheres (5-10 MBq) and 0.1 mL of non-ionic contrast is injected into the lesion under CT guidance. Then the patient is submitted to VATS. During thoracoscopy a collimated probe of 11 mm diameter connected to a gamma ray detector is introduced via an 11.5 mm trocar and the pleural surface of the suspected area is scanned. A hot spot indicates the presence of the radiolabeled nodule and hence the area to be resected. We treated 39 patients with small pulmonary nodules (mean size, 8.3 mm; range, 4-19 mm). The patients were 27 men and 12 women (mean age, 60.8 years; range, 13-80 years). Nineteen patients had a history of synchronous or metachronous malignancy. In all cases the nodule was detected and resected and the resection margins were pathologically free of tumor. Histological examination showed 21 benign and 18 malignant lesions (7 metastases and 11 primary lung cancers). Nine patients with a frozen section-based histopathological diagnosis of lung cancer without functional contraindications underwent a completion lobectomy by open surgery in the same surgical session. In conclusion, the radiolocalization of small pulmonary nodules by gamma probe during VATS is a safe and easy procedure, with fewer complications and a lower failure rate than other localization techniques. 相似文献
13.
Purpose To determine pulmonary metastasis, video assisted thoracoscopic surgery (VATS) was performed on the patients who had undergone
breast cancer surgery.
Patients and Methods p Nineteen patients with a history of breast cancer underwent VATS, because of subsequent abnormal pulmonary
shadows on chest computed tomograms (CT). All patients were suspected to have pulmonary metastasis from breast cancer.
Results The VATS procedure showed 10 (52%) patients to have pulmonary metastasis, but, 9 (48%) had primary lung cancers or benign
lesions. In the patients of pulmonary metastasis, 7 had nodular lesions (5 had a single nodule and 2 had two nodules with
a median diameter of 8.5 mm), and 3 patients had pleural dissemination. The follow-up period of the patients with pulmonary
metastasis ranged from 3 to 28 months. Three patients died of brain metastasis and respiratory failure, 3 suffered recurrence
and 4 were free from disease after VATS.
Conclusion VATS was useful for distinguishing small metastatic lesions from other diseases and a minimally invasive surgical approach
in the follow-up of breast cancer patients suspected of pulmonary metastasis. 相似文献
14.
目的探讨叶酸受体(FR)阳性循环肿瘤细胞(CTC)检测在肺部亚厘米结节(结节最大径≤10mm)良恶性诊断中的价值。方法选择2018年7月至12月首都医科大学宣武医院收治的胸部CT检查显示有最大径≤10 mm的肺小结节患者37例,包括术后病理诊断为早期肺腺癌22例、肺良性病变15例。患者术前均留取静脉血,应用新型配体靶向聚合酶链反应(LT-PCR)检测FR+CTC水平(以自定义的FU/3 ml为单位),应用酶联免疫吸附试验检测癌胚抗原(CEA)、神经元特异性烯醇化酶(NSE)、细胞角蛋白19片段CYFRA21-1、糖类抗原125(CA125)、CA199、胃泌素释放肽前体(pro-GRP)等肿瘤标志物水平。计量资料两组间比较采用t检验,以检测试剂盒说明书指定的CTC值8.70 FU/3 ml为临界值,应用二元logistic回归法分析肺结节为恶性的危险因素;采用kappa一致性检验分析以FR+CTC水平诊断与手术切除标本的病理结果诊断的一致性;绘制受试者工作特征曲线(ROC),评估各指标对肺部亚厘米结节良恶性的诊断效能。结果早期肺腺癌患者FR+CTC表达水平高于肺良性病变患者,差异有统计学意义[(11.0±3.0)FU/3 ml比(7.0±3.7)FU/3 ml,t=-3.327,P=0.001];FR+CTC水平与患者的年龄、性别、吸烟史均无相关性(均P>0.05)。经logistic回归分析显示,FR+CTC水平高为肺结节恶性的危险因素(OR=37.333,95%CI 3.994~349.010,P=0.002)。kappa一致性检验结果显示FR+CTC诊断肺亚厘米结节性质具有一定的准确性(κ=0.627,P<0.01)。ROC分析显示,FR+CTC作为诊断肺结节恶性的指标时,其诊断价值优于CEA、NSE、CYFRA21-1三者联合;FR+CTC的曲线下面积(AUC)为0.830(95%CI 0.639~0.968),诊断灵敏度为72.7%(95%CI 49.6%~88.4%),特异度为93.3%(95%CI 66.0%~99.7%);将FR+CTC、CEA、NSE、CYFRA21-1四者联合诊断肺癌时,AUC为0.776(95%CI 0.614~0.938),诊断灵敏度为86.4%,特异度为73.3%。结论FR+CTC检测对肺部亚厘米结节的良恶性诊断具有较高的价值。 相似文献
15.
孤立性肺结节的高分辨CT扫描(CT与病理对照) 总被引:2,自引:0,他引:2
目的对照高分辨CT扫描(HRCT)表现与病理的相互关系,比较HRCT与常规CT扫描(CCT)对提供肺小结节的诊断信息,提高其诊断和鉴别诊断的准确性。方法对直径≤3cm的73例(75个)良恶性结节做术前HRCT和CCT扫描,并与组织学做对照研究。结果小肺癌多呈球形(34/37例),有深分叶(28/37例)、锯齿征(33/37例)、细小毛剌(37/37例)、小泡征(19/37例)、支气管充气征(10/37例)。其病理基础为癌瘤外侵和间质纤维组织增生,肿瘤内残存正常肺组织和支气管。上述表现与良性病变有显著统计学差异。而结节内脂肪、卫星病灶、粗长毛刺、钙化、胸膜增厚粘连、浅分叶以良性为常见。与肺癌比较有显著统计学差异。HRCT在观察病变的轮廓、内部结构等方面明显优于CCT。结论HRCT有助于良恶性结节的诊断,应常规用于肺小结节的CT扫描 相似文献
16.
17.
肿瘤转移相关基因与周围型肺癌CT征象的关系研究 总被引:2,自引:0,他引:2
摘要目的:探讨VEGF和nm23-H1基因表达水平与周围型肺癌的病理生理学特征和CT征象之间的关系。方法:回顾性分析确诊的47例周围型肺癌患者CT表现.同时采用免疫组化方法(LSAB法)检测47例肺癌组织中的VEGF和nm23-H1表达水平。结果:1)VEGF、nm23-H1表达水平与原发肿瘤大小、淋巴结转移状态,pTNM分期均有密切关系(P<0.05)。2)VEGF与nm23-H1表达水平呈负相关(P<0.05)。3)VEGF基因的高表达和nm23-H1基因的低表达均与分叶征、纵隔淋巴结转移有关(P<0.05),且VEGF的高表达也与空洞征有关:二者表达水平与毛刺征、空泡征、胸膜凹陷征和支气管征均无关(P>0.05)。4)深分叶征、空泡征和支气管征与肿瘤大小有关(P<0.05),而与毛刺征、胸膜凹陷征和纵隔淋巴结转移均无关(P>0.05)。结论:VEGF过度表达和nm23-H1低表达均与周围型肺癌的分叶征、空洞坏死征和纵隔淋巴结转移有密切关系。 相似文献
18.
Shinji Shinohara Takeshi Hanagiri Masaru Takenaka Yasuhiro Chikaishi Soich Oka Hidehiko Shimokawa Makoto Nakagawa Hidetaka Uramoto Tomoko So Takatoshi Aoki Fumihiro Tanaka 《Radiology and oncology》2014,48(1):50-55
Background
This study retrospectively investigated the clinical significance of undiagnosed solitary lung nodules removed by surgical resection.Patients and methods
We retrospectively collected data on the age, smoking, cancer history, nodule size, location and spiculation of 241 patients who had nodules measuring 7 mm to 30 mm and a final diagnosis established by histopathology. We compared the final diagnosis of each patient with the probability of malignancy (POM) which was proposed by the American College of Chest Physicians (ACCP) guidelines.Results
Of the 241 patients, 203 patients were diagnosed to have a malignant lung tumor, while 38 patients were diagnosed with benign disease. There were significant differences in the patients with malignant and benign disease in terms of their age, smoking history, nodule size and spiculation. The mean value and the standard deviation of the POM in patients with malignant tumors were 51.7 + 26.1%, and that of patients with benign lesions was 34.6 + 26.7%. The area under the receiver operating characteristic (ROC) curve (AUC) was 0.67. The best cut-off value provided from the ROC curve was 22.6. When the cut-off value was set at 22.6, the sensitivity was 83%, specificity 52%, positive predictive value 90%, negative predictive value 36% and accuracy 77%, respectively.Conclusions
The clinical prediction model proposed in the ACCP guidelines showed unsatisfactory results in terms of the differential diagnosis between malignant disease and benign disease of solitary lung nodules in our study, because the specificity, negative predictive value and AUC were relatively low. 相似文献19.
背景与目的已有的研究证明:CT肺结节容积测量能够敏感反映结节容积的微小变化,在未定性肺结节的随访观察及良恶性鉴别方面具有重要应用前景。本研究旨在评估不同重建算法和层厚对CT肺结节容积测量的影响。方法对2009年12月-2011年8月在天津医科大学总医院行未定性肺结节CT随访研究的30例患者的CT图像进行后处理分析。共获取52个肺结节,应用3种不同的算法(骨密度算法、标准算法及肺算法)及层厚(0.625 mm、1.25 mm、2.5 mm)进行9次重建。由一位放射科医师应用肺结节容积分析软件进行容积测量。应用重复测量多元方差分析、相关分析及Bland-Altman法评价结节直径、算法、层厚对容积测量的影响。结果不同重建算法(F=13.6,P<0.001)、层厚(F=4.4,P=0.02)条件下测量所得的结节容积之间具有统计学差异。肺结节9次测量所得容积的变异系数和结节直径之间呈负相关(r=-0.814,P<0.001)。应用2.5mm层厚时,结节容积比1.25mm及0.625 mm层厚的一致性差,1.25 mm和0.625 mm层厚在采用骨算法时一致性最好。结论不同重建算法及层厚对肺结节容积测量有影响,尤其是直径较小的结节。在未定性肺结节尤其是肺小结节的随访过程中建议应用相同的重建参数。 相似文献
20.
随着胸部计算机断层扫描(computed tomography, CT)的广泛应用,以及肺癌高危人群筛查的逐渐开展,越来越多的“小肺癌”被发现及诊断。“小肺癌”具有的术中定位困难、侵袭性弱、近期和远期预后较好的特点为肺癌的外科治疗提出了新的挑战,本文着重从肺癌的筛查、小结节定位、肺叶切除与亚肺叶切除以及淋巴结清扫范围等方面对“小肺癌”带来的挑战进行探讨。 相似文献