免疫抑制宿主肺部感染CT表现：临床与动物实验研究
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摘要
第一部分动物实验免疫抑制兔肺部真菌感染薄层CT对照研究
【研究背景】
近年来,深部真菌感染的发病率呈上升趋势,特别是在免疫抑制人群中,如干细胞移植、实体器官移植、肿瘤放化疗患者等,其中白念珠菌、曲霉菌及隐球菌为最常见的三种深部致病真菌。早期诊断及治疗有助于提高患者生存率,但实验室检查费时且阳性率偏低,CT检查特别是薄层CT的广泛应用使得肺部病灶尽早发现成为可能,但肺部各种炎症特异性征象少,定性诊断较困难,尤其是真菌性肺炎的影像研究受限于临床病例数而无法广泛开展。动物模型的建立是研究各种疾病诊断和治疗的先决条件,本研究通过建立免疫抑制兔肺部感染白念珠菌、曲霉菌及隐球菌模型,行CT检查动态观察肺部病变进展,分析比较三类真菌性肺炎的影像学征象并与病理对照,以提高诊断正确性。
【目的】
比较免疫抑制兔肺部感染白念珠菌、曲霉菌、隐球菌的薄层CT表现,以期获得特征性诊断征象,提高诊断正确性。
【材料和方法】
新西兰大白兔72只分三批分别接种白念珠菌ATCC10235标准株、熏烟色曲霉菌及新生隐球菌H99A标准株。菌株由第二军医大学附属长征医院皮肤科真菌实验室提供,每批兔随机分为实验组和对照组。除外实验前试验麻药死亡5例,最终白念珠菌实验组17只,对照组5只;熏烟色曲霉菌实验组17只,对照组5只;新生隐球菌实验组19只,对照组4只。
根据文献建立免疫抑制兔肺部感染白念珠菌及曲霉菌模型,免疫抑制兔肺部感染新生隐球菌模型国内外文献未有记载,基本参照白念珠菌模型操作步骤。各实验组及对照组均于接种前及接种后2、4、6、8、10、12、14日行CT扫描,所有CT片均由两位主治以上影像科医师共同阅片分析。本研究所用诊断标准取自人类肺部感染诊断标准,并根据本实验具体操作部分修改。影像学统计结果录入Excel 2007,三种真菌性肺炎的CT征象及病灶分布比较采用SPSS进行x~2检验及Fisher's确切检验,P值小于0.05视为有统计学意义。
【结果】
1、三种真菌性肺炎的胸部CT表现
14例明确诊断为肺部白念珠菌感染的CT表现多样,磨玻璃影(10/14)与实变(8/14)最为多见(表5),两者常伴随出现。其它征象包括血管支气管束增粗3例,结节1例,网格或线样影1例,病灶累及双肺7例。磨玻璃影及实变影是15例熏烟曲霉菌最常见CT表现(表5),分别见13例及4例,其它征象包括血管支气管束增粗4例,网格或线样影2例,双肺受累9例,结节未见显示。16例确诊为肺部隐球菌感染中10例为磨玻璃影,5例见实变,3例血管支气管束增粗,结节、网格或线样影及气胸各1例,病灶累及双肺6例。
2、三种真菌性肺炎胸部CT征象比较
磨玻璃影在三类真菌性肺炎中均可见,其中自念珠菌肺炎14例中10例;曲霉菌肺炎15例中13例,隐球菌肺炎16例中10例。实变为三类真菌性肺炎中最常见CT征象,其中白念珠菌肺炎14例中见8例;熏烟色曲霉菌肺炎15例中见4例,隐球菌肺炎16例中见5例。总之,磨玻璃影及实变是这三种免疫抑制状态下真菌性肺炎的主要CT征象,常为两肺多发病灶,并可伴随血管支气管束增粗、结节及网格或线样影出现。但这些征象均无统计学差异。
3、三种真菌性肺炎病灶分布比较
白念珠菌肺炎、曲霉菌肺炎及隐球菌肺炎同时累及两肺比例较高,总体近一半比例,其中曲霉菌肺炎最多见,隐球菌肺炎最少,但无统计学差异。虽然熏烟曲霉菌肺炎及隐球菌肺炎累及中叶的病灶较白念珠菌肺炎多,但统计学亦显示无差异。三种真菌性肺叶在其余上、下各肺叶累及例数以及超过一叶肺累及例数上均无统计学差异。
【结论】
白念珠菌、曲霉菌及隐球菌三种真菌在免疫抑制兔肺部感染模型的薄层CT上表现相似,以实变与磨玻璃影为主,可伴随血管支气管束增粗、结节及网格或线样影出现,各征象无统计学差异。
第二部分肾移植术后肺部感染CT表现
【研究背景】
肾移植术已成为晚期肾脏疾病的重要治疗手段,肺部感染为肾移植术后最主要的感染并发症,是造成肾移植受者死亡的主要原因,早期诊断及治疗对于提高肾移植术后的长期生存率具有重要意义。胸部CT,特别是薄层扫描以及各种后处理技术的应用对于早期发现病灶有明显临床意义。但由于行肾移植术的患者数量有限,且病原体有时难以明确,有关肾移植后肺部感染的影像学表现缺少大样本量研究资料。
【目的】
分析肾移植术后肺部感染CT图像,获得不同病原体肺部感染的特征性CT表现。
【材料和方法】
检索2000年5月—2008年2月长征医院病历,收集肾移植术后肺部感染446例进行回顾性分析,其中行胸部CT扫描并于一周内明确诊断的有121例。肺部感染诊断依据包括下呼吸道临床症状、CT肺部感染表现、微生物学检验或病理检查阳性、或临床试验治疗有效。使用CT扫描仪包括:Marconi Mx8000型4层螺旋CT仪,TOSHIBA Aquilion 16层螺旋CT,LightSpeed VCT64层扫描仪。患者平静呼吸下屏气,自肺尖扫描至肺底。部分图像行多平面重建(MPR)、最大密度投影(MIP)、最小密度投影(mIP)以及容积重建(VR)。所有CT片均由两位影像科医师共同阅片,分析征象包括:磨玻璃影,网格或线样影,结节,实变,树芽征,血管支气管束增粗,胸腔积液,胸膜增厚,肺气囊,淋巴结肿大等;同时判断磨玻璃影、网格或线样影、结节的分布特征。临床及影像学结果录入Excel 2007,采用SPSS进行x~2检验及Fisher's确切检验,P值小于0.05视为有统计学意义。
【结果】
一、肾移植术后肺部感染基本情况
1、年度感染情况
2001至2006年各年份肾移植后肺部感染发生例数大致相仿,2007年增加较明显。每年7—8月以及2—3月为肺部感染好发季节。
2、肺部感染发生时间
446例肾移植患者术后1个月内发病65例(14.6%),1—3个月发病147例(32.9%),3—6个月发病91例(20.4%),6—12个月23例(5.2%),1年以上120例(26.9%)。肾移植后肺部感染好发时间为术后2—4月,高峰为术后3个月左右。446例中38人因肺部感染死亡,死亡率8.5%。
121例行胸部CT扫描者中男性93例,女性28例,年龄14—71岁,平均42.7岁,肺部感染发生时间从术后10—4522 d不等,1个月内发病者7例,1—3个月发病36例,3—6个月发病19例,6—12个月8例,1年以上51例。移植术后1个月内细菌感染比例高;第2～6个月细菌、混合感染以及病毒感染为主;1年以后真菌、结核杆菌感染率明显增加,细菌、病毒、混合感染数量较稳定。
3、肺部感染病原体
按病原体出现频次分析发现121例肺部感染中89例临床明确病原体诊断,细菌(28%)和混合感染(28%)最为常见,真菌(7%)、结核(6%)感染次之,病毒感染(4%)最少。单纯细菌感染和混合感染中含细菌感染者共计65例,约占肾移植术后明确病原体感染的2/3,其中革兰氏阴性杆菌、葡萄球菌、链球菌为常见致病菌,革兰氏阴性杆菌比例最高。病毒感染均为巨细胞病毒。真菌病原体主要为白念珠菌和霉菌。
二、肾移植术后肺部感染CT表现
1、不同病原体感染的胸部CT表现
7例结核感染者中6例胸部CT异常;树芽征为最常见表现(n=4);4例多发小结节中3例为小叶中心结节,1例为随机分布结节,磨玻璃影3例;实变2例;血管支气管束增粗2例;胸腔积液3例:网格或线样影2例;1例纵隔淋巴结肿大,内部有坏死。
细菌感染34例,其中磨玻璃影24例,20例为弥漫型,4例为局灶型。结节23例,14例为小叶中心结节,9例为随机分布结节;大于1cm结节1例,其余直径均小于1cm;1例直径5mm结节伴晕征。网格或线样影20例,其中17例弥漫型;16例网格或线样影主要累及双下肺;20例网格或线样影中11例伴随磨玻璃影出现,4例伴实变,5例同时伴磨玻璃影和实变影。实变11例,大部分累及下肺。
病毒感染:5例巨细胞病毒感染胸部CT均为异常,其中磨玻璃影4例均合并其它表现:网格或线样影2例,结节2例,血管支气管束增粗2例;网格或线样影3例均为弥漫分布;多发小结节2例,结节直径均小于1cm。合并细菌和/或真菌感染的巨细胞肺炎12例,9例见弥漫磨玻璃影;网格或线样影10例,多发9例,中下肺野居多;结节8例;实变4例,血管支气管束增粗4例。无论是单独巨细胞病毒感染或是与其它病原体共同感染,其影象学表现均以弥漫性磨玻璃影为主,并合并网格或线样影、多发小结节等多种表现。
9例真菌感染中网格或线样影最常见,其中2例合并磨玻璃影;多发结节4例,1例熏烟色曲霉菌感染见2枚直径大于1cm结节,伴晕征;磨玻璃影3例中2例为弥漫型。实变2例;胸膜增厚6例;血管支气管束增粗4例。1例白念珠菌和曲霉菌二重感染见弥漫分布磨玻璃影合并网格或线样影及多发小叶中心结节,伴双侧胸膜增厚。
混合感染包括细菌二重感染、真菌二重感染、细菌、真菌、病毒混合感染。CT表现为磨玻璃样影、网格或线样影、结节、实变、空洞、胸膜增厚等征象混合存在。
2、肺部感染的各种CT征象
树芽征见于4例肺结核(P=0.049)、2例真菌感染、1例巨细胞病毒感染、5例细菌感染、1例混合感染中。
磨玻璃影在各类感染中均可见,其中巨细胞病毒5例中见4例,均为弥漫型分布;细菌感染24例,其中弥漫型20例;混合感染20例中17例为弥漫型;真菌感染3例均为弥漫型;结核3例中仅1例为弥漫型,其余2例为局灶型。
结节在34例细菌感染中出现23例,其中14例为小叶中心结节,9例随机分布;肺结核中4例,其中3例小叶中心结节,1例随机分布;混合感染中结节19例,其中13例随机分布结节,小叶中心型及淋巴管周围分布各3例;真菌感染中结节4例,2例小叶中心结节,随机分布及淋巴管周围分布各1例;巨细胞病毒感染5例中结节2例,小叶中心及随机分布各1例。
网状或线样影在各型感染中出现机率均较高,混合感染中23例:20例为弥漫型,3例局灶型;真菌感染6例以及巨细胞病毒感染3例均为弥漫型;细菌感染20例中17例为弥漫型,肺结核3例中2例弥漫型,1例为局灶型。
实变于细菌感染中表现为单发8例,多发3例;斑片和节段性分布分别为7例和3例。混合感染中多发病灶7例,单发1例;斑片和节段性分布各5例。肺结核中2例多发,斑片和节段性分布各1例;真菌感染中斑片样2例,单发与多发病灶各1例;病毒感染5例中未见实变征象
其余CT表现包括:血管支气管束增粗,胸腔积液,胸膜增厚,心包积液,肺气囊,在各类感染中均无统计学差异(所有P＞0.05)。
【结论】
细菌为肾移植术后肺部感染最常见病原体,混合感染比例高,机遇性感染较少。术后2—4月为肺部感染好发时期,其中术后3个月为高峰期;移植后1个月内细菌感染比例高;第2～6个月细菌、混合感染以及病毒感染为主;1年以后真菌、结核杆菌感染率明显增加,细菌、病毒、混合感染数量较稳定。肾移植后肺部感染的CT表现多样,特征性征象少,磨玻璃影、网格或线样影以及多发小结节易出现于各类感染中;各病原体胸部CT表现均为各种征象混合存在,除“树芽征”在结核中出现频率较高,其它征象均无统计学差异;大于1cm的结节伴晕征提示曲霉菌感染可能,同时行增强扫描后处理重建获得血管闭塞或受侵信息有助于曲霉菌早期诊断;CMV感染弥漫型磨玻璃影多见,真菌感染网格或线样影多见;细菌、混合感染、真菌感染实变相对较多,两下肺背侧节段性实变可转化为线样影、磨玻璃影逐渐消散,系炎症好转表现;炎症所致胸膜肥厚有一定诊断价值;多层CT各种后处理重建(MPR、MIP、mIP、VR)有助于显示肺部感染所致实质、气道、血管改变,特别是MPR、MIP对于实变的判定、MIP对于多发小结节、树芽征的显示及定性有重要意义。肾移植术后肺部CT后处理重建应广泛应用于临床,与轴位图像互为补充。
Part one Comparison with Thin-Section CT Findings of Candida albicans pneumonia,Aspergillus fumigates pneumonia and Cryptococcus neoformans pneumonia in persistently neutropenic rabbits
【Background】
The incidence of fungal infection increased in the past few years,and occured most commonly after bone marrow and solid organ transplantation and in patients with AIDS. CT examination,especially thin-section CT and postprocessing techniques may show pulmonary abnormalities,which is superior to radiography in depicting the pattern and extent of abnormalities.But most clinic studies have been limited to a relatively small number of patients,little information is available about CT features that may allow distinction among the various types of fungal infections.
【Objective】
To compare thin-section CT findings of C albicans pneumonia with those of A fumigates pneumonia and C neoformans pneumonia in persistently neutropenic rabbits.
【Methods】
A total of 72 healthy New Zealand White rabbits were used for all experiments.10~8 blastoconidia of C albicans ATCC10235;C neoforman H99A and 10~7 A fumigates obtained from departmrnt of dermatology of Changzheng hospital were inoculated in persistently neutropenic rabbits.C albicans group(n=19),control group(n=3);A fumigates group(n=19),control group(n=3);C neoformans group(n=19),and control group(n=3) were eventually used except five death before the experiment.C albicans and A fumigates models have especially been predictive of the clinical outcomes of treatments with antifungal agents in neutropenic hosts,but C neoforman pneumonia in persistently neutropenic rabbits were not recorded from the literature,and we operated in the same way with C albicans model.The diagnostic approach was based on the Clinical Pulmonary Infection Score,modified for use in rabbits.Thin-section CT scan was performed before inoculation and at 2、4、6、8、10、12、14d after inoculation respectively.CT scans of each rabbit were retrospectively and independently assessed by two chest radiologists for the pattern of the pulmonary abnormalities(ground-glass attenuation(GGO),consolidation, nodules,reticular or linear opacity,thickening of the bronchovascular bundles,pleural effusion),and the distribution of the lesion(unilateral or bilateral;upper,middle or lower lung lobes;more than one lobe involved).Consensus was reached for disagreements.CT data were entered into a spreadsheet(Excel 2007,Microsoft).Statistical analysis was performed using the x~2 test and the Fisher's exact test,a P value of less than 0.05 was considered statistically significant.
【Results】
1,Thin-Section CT findings for each type of pneumonia
The CT manifestations were variable in neutropenic rabbits with C albicans pneumonia,consolidation(10/14) and ground-glass attenuation(8/14) were the most common findings,bronchovascular bundle thickening(3/14),nodule(2/14),and reticular or linear opacity(1/14) followed.Bilateral lung involvement was demonstrated in four cases.
GGO(11/15) and consolidation(9/15) were the most common findings in neutropenic rabbits with A fumigates pneumonia.Bronchovascular bundle thickening was seen in four rabbits,and reticular or linear opacity was seen in two.Bilateral lung involvement was seen in nine cases,but nodules were not observed in any case with A fumigates pneumonia.
16 rabbits had C neoformans pneumonia.14 of these cases had consolidation,and associated with ground-glass attenuation in 12 cases;ground-glass attenuation was seen in 13 cases.Three cases had bronchovascular bundle thickening,and nodular opacities, pneumothorax,reticular or linear opacity were respectively seen in one rabbit.Bilateral lung involvement was seen in about half of the patients with C neoformans pneumonia,
3、Comparison of Thin-Section CT Findings In brief,ground-glass attenuation and air-space consolidation were the most common findings in neutropenic rabbits with these three fungal pneumonias,and occasionally associated with bronchovascular bundle thickening,nodules and reticular or linear opacity. There was no stastistically significant difference in the prevalence of these CT patterns.
4、Comparison of frequency of Lobe Involvement
Although the presence of pulmonary lesion in middle lobes was higher in rabbits with A fumigates pneumonia and C neoformans pneumonia than in that with C albicans pneumonia,the difference was not statistically significant The frequency of involvement in other lobes and the frequency of involvement in more than one lobe were not statistically different between the three kinds of pneumonia.
【Conclusion】
C albicans pneumonia demonstrates a wide spectrum of thin-section CT findings that are similar to those of A fumigates and C neoformans;ground-glass attenuation and air-space consolidation are the most common findings,and usually associated with other findings,including bronchovascular bundle thickening,nodules and reticular or linear opacity;the difference of all the CT findings is not statistically significant.
Part Two Pulmonary infections after kidney transplantation:Analysis of CT appearance in 121 Patients
【Background】
Pulmonary infections are a common cause of morbidity and mortality after kidney transplantation.Pathogens include bacteria,fungi,virus,and so on.Early and accurate diagnosis is clinically important,but difficult.CT examination,especially thin-section CT and postprocessing Techniques may show pulmonary abnormalities in patients with normal findings on radiographs and is superior to radiography in depicting the pattern and extent of abnormalities.Several studies have described the thin-section CT manifestations of pulmonary infections in kidney transplant patients.These studied have been limited to a relatively small number of patients and have focused mainly on the description of specific infections,few information is available about CT features that may allow distinction among the various types of infections.
【Objective】
The purpose of this study was to review the CT findings in patients with pulmonary infection after kidney transplantation and to determine distinguishing features among various types of infection。
【Methods】
The patients were selected by a review of the medical records at our institution from May 2000 to February 2008 and came from a population Of 446 patients who had been proven pulmonary infection after kidney transplantation.We identified 121 patients who had undergone thin-section CT of the chest and proven diagnosis within 1 week of the CT scans.The Pulmonary infiltration was considered to be infectious when there was clinical suspicion of a lower respiratory tract infection,the.presence of radiologic findings,a microbial agent isolated in respiratory and/or nonrespiratory samples,or improvement after specific treatment.
Marconi MxS000(Siemens,Erlangen,Germany),Toshiba Aquilion(Toshiba Medical Systems,Tokyo,Japan),or Lightspeed VCT(General Electric Medical Systems, Milwaukee,WI) were used.The lungs were scanned at end-inspiration from the apex of the lung to the diaphragm.Postprocessing tools,including multiplanar reconstruction (MPR),maximum intensity projection(MIP) and minimum intensity projection(mIP),and volume rendering(VR),were used in some cases.The images were interpreted independently by two radiologists,who were blinded to the findings of other imaging modalities and the final diagnosis.The following CT findings were evaluated:pattern of the pulmonary abnormalities(GGO,reticular or linear opacity,air-space consolidation, nodules,tree-in-bud pattern,bronchovascular bundle thickening,pleural effusion,pleural thickening,and lymphadenopathy);distribution of the lesion(GGO,nodules,reticular or linear opacity).The clinical and CT data were entered into a spreadsheet(Excel 2007, Microsoft).Statistical analysis was performed using the x~2 test and the Fisher's exact test, a P value of less than 0.05 was considered statistically significant.
【Results】
一、Distributions of pulmonary infections in Kidney Transplant Recipients
1、Time distributions:The incidence of pulmonary infections almost the same from 2001 to 2006,and have obviously increase in 2007.July to august and February to march were the most common season for these patients.
2、Time Course:Pulmonary infections were diagnosed in 446 cases,which are more likely to occur in the time period between 2 and 4 months posttransplantation,with a peak incidence in the 3 months after the procedure.65(14.6%) episodes occurred in the first 30 days,147(32.9%) cases in the time period between 1 and 3 months,91(20.4%) cases between 3 and 6 months,23(5.2%) cases between 6 and 12 months,120(26.9%) cases after 12 months of transplantation,the mortality rate was 8.5%.In the first month after procedure,bacterial pathogens were predominately.One to 6 months following transplant, bacterial、virus(CMV) and mixed infection are seen commonly.After 12 months of transplantation,bacterial、virus(CMV) and mixed infection remains a concern but mycobacterial and fungal infections should be considered as potential causes for infiltrates.
The study group(121 cases) was composed of 28 females and 93 males who ranged in age from 14 to 71 years(mean age 42.7 years).Pulmonary infection Occured from 10 to 4522 days posttransplantation,7 episodes occurred in the first 30 days,36 cases in the time period between 1 and 3 months posttransplantation,19 cases in the time period between 3 and 6 months posttransplantation,8 cases between 6 and 12 months posttransplantation, 51 cases after 12 months of transplantation.
3、Infectious Etiologies:In the 121 patients enrolled as having pneumonia,89 patients had a definite etiologic diagnosis.Bacterial(28%) and mixed infections(28%) were the most common causes of pneumonia,followed by fungi(7%),TB(6%) and CMV(4%). More than 2/3rd of pulmonary infections in kidney transplant recipients can be attributed to bacterial organisms,Staphylococcus,Streptococcus pneumonia,and Gram-negative bacilli were the most common bacterial pathogens.All the virus pneumonia was caused by CMV.Candida albicans and Aspergillus were the most common fungal pathogens.
二、CT Appearance in Kidney Transplant Recipients
1,CT findings of the various infections
Pulmonary tuberculosis was diagnosed in 7 patients,and abnormalities were shown in 6 patients.Tree-in-bud pattem(n=4) was the most common finding in these patients.Small nodules were seen in 4 patients,GGO was seen in three patients,consolidation was seen in two,pleural effusion was seen in three,reticular or linear opacity in two,and mediastinal lymphadenopathy in one.
34 cases had bacterial pneumonia.24 of these patients had GGO,twenty of which were diffuse,and four,focal.23 cases had nodular opacities,including 14 patients with centrilobular nodules and nine with random nodules;22 patients with small nodules and one with large nodules;One surround by halo sign.Reticular or linear opacity was seen in 20 patients,seventeen of which were diffuse,and three,patchy.Reticular or linear opacity was involved mainly the lower lung zone in 16 patients,associated with ground-glass attenuation in 11 cases;with consolidation in 4 cases,and both in five.Consolidation was seen in 11 patients and involved mainly the lower lung zone.
CMV pneumonia:all 5 patients with CMV pneumonia had abnormal findings on CT scans.GGO was seen in 4 of 5 patients.These areas were all diffuse.In all four cases, ground-glass attenuation was associated with other abnormalities,including reticular or linear opacity(n=2),small nodules(n=2).Reticular or linear opacity were identified in 3 of 5 patients.These areas were all diffuse too.Multiple nodules were identified in 2 of 5 patients.All nodules were smaller than 10mm in diameter.Overall,the major of 5 patients with CMV pneumonia and 12 patients with mixed CMV pneumonia had GGO combined with reticular or linear opacity,nodules,tree-in-bud patterns.
Fungal pneumonia:Reticular or linear opacity was the most common finding in these nine patients and associated with ground-glass opacities in two cases.GGO was seen in three patients,diffuse in two cases and focal in one.four cases had nodular opacities.Two large nodules surrounded by halo sign were seen in one patient with Aspergillus organisms. Air-space consolidation was seen in two patients,pleural thickening was seen in six patients,thickening of the bronchovascular bundle was seen in four patients,and tree-in-bud pattern was seen in two.
For mixed infections,the CT manifestations were variable,which consisted of reticular or linear opacity,GGO,nodules,consolidation,pleural effusion,thickening of the bronchovascular bundles,or a combination of these patterns.
2,comparison of the CT findings of the various infections
Tree-in-bud pattern was seen in 4 of 7 patients with tuberculosis,5 of 34 patients with bacterial pneumonia,2 of 9 patients with fungal pneumonia,2 of 5 patients with CMV pneumonia,1 of 34 patients with mixed infections.Tree-in-bud pattern(P=0.049) was significantly more frequent in patients with tuberculosis than in those with bacterial pneumonia.
GGO was present in 24 of 34 patients with bacterial pneumonia,diffuse in 20 cases and focal in four.4 of 5 patients with CMV pneumonia and 3 of 9 patients with fungal pneumonia were diffuse.20 of 34 patients with mixed infection,diffuse in 17 cases and focal in three.3 of 7 patients with pulmonary tuberculosis,diffuse in one case and focal in two.
Nodules were present in 23 of 34 patients with bacterial pneumonia,centrilobular in 14 cases and random in 9.4 of 7 patients with pulmonary tuberculosis,centrilobular in three cases and random in one.19 of 34 patients with mixed infection,random in 13 cases.4 of 9 patients had fungal pneumonia.2 of 5 patients had CMV pneumonia.
Reticular or linear opacity was present in 23 of 34 patients with mixed infection, diffuse in 20 cases and focal in three.3 of 5 patients with CMV pneumonia and 6 of 9 patients with fungal pneumonia were all diffuse.20 of 34 patients had bacterial pneumonia, diffuse in 17 and focal in 3.3 of 7 patients had tuberculosis.
Air-space consolidation was present in 2 of 7 patients with tuberculosis and 2 of 9 patients with fungal pneumonia,11 of 34 patients with bacterial pneumonia,focal in 8 cases and multifocal in three,patchy in seven and Segmental in three.7 of 34 patients with mixed infection,focal in one case and multifocal in seven,patchy in five cases and Segmental in five.Consolidation was not present in patient with CMV pneumonia.
There was no stastistically significant difference in the prevalence of the CT patterns including GGO,reticular or linear opacity,nodules,air-space consolidation,pleural effusion,bronchovascular bundle thickening,Tree-in-bud pattern,and pleural thickening, among tuberculosis,bacterial,viral,fungal,mixed infections(all P＞0.05).
【Conclusion】
Our study shows that bacterial infection is the commonest cause of post kidney transplant pulmonary infection and more than 1/4rd of pulmonary infections can be attributed to multiple organisms.Pulmonary infections are more likely to occur in the time period between 2 and 4 months posttransplantation,with a peak incidence in the 3 months. In the first month after procedure,bacterial pathogens were predominately.One to 6 months following transplant,bacterial,virus(CMV) and mixed infection are commonly observed.After 12 months of transplantation,bacterial、virus(CMV) pneumonia and mixed infection remains a concern but mycobacterial and fungal infections should be considered as potential causes for infiltrates.The CT manifestations consist of reticular or linear opacity,GGO,nodules,consolidation,pleural effusion,bronchovascular bundle thickening,or a combination of these patterns;Tree-in-bud pattern were significantly more frequent in patients with tuberculosis than in those with bacterial pneumonia.Other CT patters are not helpful in distinguish among the various types of infection seen in kidney transplant recipients.The presence of large nodules surrounded by halo sign is most suggestive of Aspergillus infection.MDCT angiography has been shown to be a feasible technique to depict directly vessel occlusion in the setting of suspected fungal infections, especially for early diagnosis of angioinvasive pulmonary Aspergillosis in renal transplant recipients.Ground-glass attenuation is commonly seen in CMV pneumonia,and Reticular or linear opacity is common observed in fungal infection.Air-space consolidation is relatively common seen in bacterial,fungal and mixed pneumonia than other pathogens. Segmental consolidation in posterior of lower lung zone may gradually vanished by reversion to linear opacity,GGO.Pleural thickening is a valuable sign to judge the pulmonary infection.MDCT allows contiguous visualization of the lung parenchyma,the blood vessels and the airways.Postprocessing tools,including MPR,MIP,mIP,and VR, are used to help quantify the various patterns(MIP permits the detection and characterization of micronodules and tree-in-bud pattern;quantification the extent of air-space consolidation),assess the distribution and extent of these signs to help differentiate different type infections.
【研究背景】
近年来,深部真菌感染的发病率呈上升趋势,特别是在免疫抑制人群中,如干细胞移植、实体器官移植、肿瘤放化疗患者等,其中白念珠菌、曲霉菌及隐球菌为最常见的三种深部致病真菌。早期诊断及治疗有助于提高患者生存率,但实验室检查费时且阳性率偏低,CT检查特别是薄层CT的广泛应用使得肺部病灶尽早发现成为可能,但肺部各种炎症特异性征象少,定性诊断较困难,尤其是真菌性肺炎的影像研究受限于临床病例数而无法广泛开展。动物模型的建立是研究各种疾病诊断和治疗的先决条件,本研究通过建立免疫抑制兔肺部感染白念珠菌、曲霉菌及隐球菌模型,行CT检查动态观察肺部病变进展,分析比较三类真菌性肺炎的影像学征象并与病理对照,以提高诊断正确性。
【目的】
比较免疫抑制兔肺部感染白念珠菌、曲霉菌、隐球菌的薄层CT表现,以期获得特征性诊断征象,提高诊断正确性。
【材料和方法】
新西兰大白兔72只分三批分别接种白念珠菌ATCC10235标准株、熏烟色曲霉菌及新生隐球菌H99A标准株。菌株由第二军医大学附属长征医院皮肤科真菌实验室提供,每批兔随机分为实验组和对照组。除外实验前试验麻药死亡5例,最终白念珠菌实验组17只,对照组5只;熏烟色曲霉菌实验组17只,对照组5只;新生隐球菌实验组19只,对照组4只。
根据文献建立免疫抑制兔肺部感染白念珠菌及曲霉菌模型,免疫抑制兔肺部感染新生隐球菌模型国内外文献未有记载,基本参照白念珠菌模型操作步骤。各实验组及对照组均于接种前及接种后2、4、6、8、10、12、14日行CT扫描,所有CT片均由两位主治以上影像科医师共同阅片分析。本研究所用诊断标准取自人类肺部感染诊断标准,并根据本实验具体操作部分修改。影像学统计结果录入Excel 2007,三种真菌性肺炎的CT征象及病灶分布比较采用SPSS进行x~2检验及Fisher's确切检验,P值小于0.05视为有统计学意义。
【结果】
1、三种真菌性肺炎的胸部CT表现
14例明确诊断为肺部白念珠菌感染的CT表现多样,磨玻璃影(10/14)与实变(8/14)最为多见(表5),两者常伴随出现。其它征象包括血管支气管束增粗3例,结节1例,网格或线样影1例,病灶累及双肺7例。磨玻璃影及实变影是15例熏烟曲霉菌最常见CT表现(表5),分别见13例及4例,其它征象包括血管支气管束增粗4例,网格或线样影2例,双肺受累9例,结节未见显示。16例确诊为肺部隐球菌感染中10例为磨玻璃影,5例见实变,3例血管支气管束增粗,结节、网格或线样影及气胸各1例,病灶累及双肺6例。
2、三种真菌性肺炎胸部CT征象比较
磨玻璃影在三类真菌性肺炎中均可见,其中自念珠菌肺炎14例中10例;曲霉菌肺炎15例中13例,隐球菌肺炎16例中10例。实变为三类真菌性肺炎中最常见CT征象,其中白念珠菌肺炎14例中见8例;熏烟色曲霉菌肺炎15例中见4例,隐球菌肺炎16例中见5例。总之,磨玻璃影及实变是这三种免疫抑制状态下真菌性肺炎的主要CT征象,常为两肺多发病灶,并可伴随血管支气管束增粗、结节及网格或线样影出现。但这些征象均无统计学差异。
3、三种真菌性肺炎病灶分布比较
白念珠菌肺炎、曲霉菌肺炎及隐球菌肺炎同时累及两肺比例较高,总体近一半比例,其中曲霉菌肺炎最多见,隐球菌肺炎最少,但无统计学差异。虽然熏烟曲霉菌肺炎及隐球菌肺炎累及中叶的病灶较白念珠菌肺炎多,但统计学亦显示无差异。三种真菌性肺叶在其余上、下各肺叶累及例数以及超过一叶肺累及例数上均无统计学差异。
【结论】
白念珠菌、曲霉菌及隐球菌三种真菌在免疫抑制兔肺部感染模型的薄层CT上表现相似,以实变与磨玻璃影为主,可伴随血管支气管束增粗、结节及网格或线样影出现,各征象无统计学差异。
第二部分肾移植术后肺部感染CT表现
【研究背景】
肾移植术已成为晚期肾脏疾病的重要治疗手段,肺部感染为肾移植术后最主要的感染并发症,是造成肾移植受者死亡的主要原因,早期诊断及治疗对于提高肾移植术后的长期生存率具有重要意义。胸部CT,特别是薄层扫描以及各种后处理技术的应用对于早期发现病灶有明显临床意义。但由于行肾移植术的患者数量有限,且病原体有时难以明确,有关肾移植后肺部感染的影像学表现缺少大样本量研究资料。
【目的】
分析肾移植术后肺部感染CT图像,获得不同病原体肺部感染的特征性CT表现。
【材料和方法】
检索2000年5月—2008年2月长征医院病历,收集肾移植术后肺部感染446例进行回顾性分析,其中行胸部CT扫描并于一周内明确诊断的有121例。肺部感染诊断依据包括下呼吸道临床症状、CT肺部感染表现、微生物学检验或病理检查阳性、或临床试验治疗有效。使用CT扫描仪包括:Marconi Mx8000型4层螺旋CT仪,TOSHIBA Aquilion 16层螺旋CT,LightSpeed VCT64层扫描仪。患者平静呼吸下屏气,自肺尖扫描至肺底。部分图像行多平面重建(MPR)、最大密度投影(MIP)、最小密度投影(mIP)以及容积重建(VR)。所有CT片均由两位影像科医师共同阅片,分析征象包括:磨玻璃影,网格或线样影,结节,实变,树芽征,血管支气管束增粗,胸腔积液,胸膜增厚,肺气囊,淋巴结肿大等;同时判断磨玻璃影、网格或线样影、结节的分布特征。临床及影像学结果录入Excel 2007,采用SPSS进行x~2检验及Fisher's确切检验,P值小于0.05视为有统计学意义。
【结果】
一、肾移植术后肺部感染基本情况
1、年度感染情况
2001至2006年各年份肾移植后肺部感染发生例数大致相仿,2007年增加较明显。每年7—8月以及2—3月为肺部感染好发季节。
2、肺部感染发生时间
446例肾移植患者术后1个月内发病65例(14.6%),1—3个月发病147例(32.9%),3—6个月发病91例(20.4%),6—12个月23例(5.2%),1年以上120例(26.9%)。肾移植后肺部感染好发时间为术后2—4月,高峰为术后3个月左右。446例中38人因肺部感染死亡,死亡率8.5%。
121例行胸部CT扫描者中男性93例,女性28例,年龄14—71岁,平均42.7岁,肺部感染发生时间从术后10—4522 d不等,1个月内发病者7例,1—3个月发病36例,3—6个月发病19例,6—12个月8例,1年以上51例。移植术后1个月内细菌感染比例高;第2～6个月细菌、混合感染以及病毒感染为主;1年以后真菌、结核杆菌感染率明显增加,细菌、病毒、混合感染数量较稳定。
3、肺部感染病原体
按病原体出现频次分析发现121例肺部感染中89例临床明确病原体诊断,细菌(28%)和混合感染(28%)最为常见,真菌(7%)、结核(6%)感染次之,病毒感染(4%)最少。单纯细菌感染和混合感染中含细菌感染者共计65例,约占肾移植术后明确病原体感染的2/3,其中革兰氏阴性杆菌、葡萄球菌、链球菌为常见致病菌,革兰氏阴性杆菌比例最高。病毒感染均为巨细胞病毒。真菌病原体主要为白念珠菌和霉菌。
二、肾移植术后肺部感染CT表现
1、不同病原体感染的胸部CT表现
7例结核感染者中6例胸部CT异常;树芽征为最常见表现(n=4);4例多发小结节中3例为小叶中心结节,1例为随机分布结节,磨玻璃影3例;实变2例;血管支气管束增粗2例;胸腔积液3例:网格或线样影2例;1例纵隔淋巴结肿大,内部有坏死。
细菌感染34例,其中磨玻璃影24例,20例为弥漫型,4例为局灶型。结节23例,14例为小叶中心结节,9例为随机分布结节;大于1cm结节1例,其余直径均小于1cm;1例直径5mm结节伴晕征。网格或线样影20例,其中17例弥漫型;16例网格或线样影主要累及双下肺;20例网格或线样影中11例伴随磨玻璃影出现,4例伴实变,5例同时伴磨玻璃影和实变影。实变11例,大部分累及下肺。
病毒感染:5例巨细胞病毒感染胸部CT均为异常,其中磨玻璃影4例均合并其它表现:网格或线样影2例,结节2例,血管支气管束增粗2例;网格或线样影3例均为弥漫分布;多发小结节2例,结节直径均小于1cm。合并细菌和/或真菌感染的巨细胞肺炎12例,9例见弥漫磨玻璃影;网格或线样影10例,多发9例,中下肺野居多;结节8例;实变4例,血管支气管束增粗4例。无论是单独巨细胞病毒感染或是与其它病原体共同感染,其影象学表现均以弥漫性磨玻璃影为主,并合并网格或线样影、多发小结节等多种表现。
9例真菌感染中网格或线样影最常见,其中2例合并磨玻璃影;多发结节4例,1例熏烟色曲霉菌感染见2枚直径大于1cm结节,伴晕征;磨玻璃影3例中2例为弥漫型。实变2例;胸膜增厚6例;血管支气管束增粗4例。1例白念珠菌和曲霉菌二重感染见弥漫分布磨玻璃影合并网格或线样影及多发小叶中心结节,伴双侧胸膜增厚。
混合感染包括细菌二重感染、真菌二重感染、细菌、真菌、病毒混合感染。CT表现为磨玻璃样影、网格或线样影、结节、实变、空洞、胸膜增厚等征象混合存在。
2、肺部感染的各种CT征象
树芽征见于4例肺结核(P=0.049)、2例真菌感染、1例巨细胞病毒感染、5例细菌感染、1例混合感染中。
磨玻璃影在各类感染中均可见,其中巨细胞病毒5例中见4例,均为弥漫型分布;细菌感染24例,其中弥漫型20例;混合感染20例中17例为弥漫型;真菌感染3例均为弥漫型;结核3例中仅1例为弥漫型,其余2例为局灶型。
结节在34例细菌感染中出现23例,其中14例为小叶中心结节,9例随机分布;肺结核中4例,其中3例小叶中心结节,1例随机分布;混合感染中结节19例,其中13例随机分布结节,小叶中心型及淋巴管周围分布各3例;真菌感染中结节4例,2例小叶中心结节,随机分布及淋巴管周围分布各1例;巨细胞病毒感染5例中结节2例,小叶中心及随机分布各1例。
网状或线样影在各型感染中出现机率均较高,混合感染中23例:20例为弥漫型,3例局灶型;真菌感染6例以及巨细胞病毒感染3例均为弥漫型;细菌感染20例中17例为弥漫型,肺结核3例中2例弥漫型,1例为局灶型。
实变于细菌感染中表现为单发8例,多发3例;斑片和节段性分布分别为7例和3例。混合感染中多发病灶7例,单发1例;斑片和节段性分布各5例。肺结核中2例多发,斑片和节段性分布各1例;真菌感染中斑片样2例,单发与多发病灶各1例;病毒感染5例中未见实变征象
其余CT表现包括:血管支气管束增粗,胸腔积液,胸膜增厚,心包积液,肺气囊,在各类感染中均无统计学差异(所有P＞0.05)。
【结论】
细菌为肾移植术后肺部感染最常见病原体,混合感染比例高,机遇性感染较少。术后2—4月为肺部感染好发时期,其中术后3个月为高峰期;移植后1个月内细菌感染比例高;第2～6个月细菌、混合感染以及病毒感染为主;1年以后真菌、结核杆菌感染率明显增加,细菌、病毒、混合感染数量较稳定。肾移植后肺部感染的CT表现多样,特征性征象少,磨玻璃影、网格或线样影以及多发小结节易出现于各类感染中;各病原体胸部CT表现均为各种征象混合存在,除“树芽征”在结核中出现频率较高,其它征象均无统计学差异;大于1cm的结节伴晕征提示曲霉菌感染可能,同时行增强扫描后处理重建获得血管闭塞或受侵信息有助于曲霉菌早期诊断;CMV感染弥漫型磨玻璃影多见,真菌感染网格或线样影多见;细菌、混合感染、真菌感染实变相对较多,两下肺背侧节段性实变可转化为线样影、磨玻璃影逐渐消散,系炎症好转表现;炎症所致胸膜肥厚有一定诊断价值;多层CT各种后处理重建(MPR、MIP、mIP、VR)有助于显示肺部感染所致实质、气道、血管改变,特别是MPR、MIP对于实变的判定、MIP对于多发小结节、树芽征的显示及定性有重要意义。肾移植术后肺部CT后处理重建应广泛应用于临床,与轴位图像互为补充。
Part one Comparison with Thin-Section CT Findings of Candida albicans pneumonia,Aspergillus fumigates pneumonia and Cryptococcus neoformans pneumonia in persistently neutropenic rabbits
【Background】
The incidence of fungal infection increased in the past few years,and occured most commonly after bone marrow and solid organ transplantation and in patients with AIDS. CT examination,especially thin-section CT and postprocessing techniques may show pulmonary abnormalities,which is superior to radiography in depicting the pattern and extent of abnormalities.But most clinic studies have been limited to a relatively small number of patients,little information is available about CT features that may allow distinction among the various types of fungal infections.
【Objective】
To compare thin-section CT findings of C albicans pneumonia with those of A fumigates pneumonia and C neoformans pneumonia in persistently neutropenic rabbits.
【Methods】
A total of 72 healthy New Zealand White rabbits were used for all experiments.10~8 blastoconidia of C albicans ATCC10235;C neoforman H99A and 10~7 A fumigates obtained from departmrnt of dermatology of Changzheng hospital were inoculated in persistently neutropenic rabbits.C albicans group(n=19),control group(n=3);A fumigates group(n=19),control group(n=3);C neoformans group(n=19),and control group(n=3) were eventually used except five death before the experiment.C albicans and A fumigates models have especially been predictive of the clinical outcomes of treatments with antifungal agents in neutropenic hosts,but C neoforman pneumonia in persistently neutropenic rabbits were not recorded from the literature,and we operated in the same way with C albicans model.The diagnostic approach was based on the Clinical Pulmonary Infection Score,modified for use in rabbits.Thin-section CT scan was performed before inoculation and at 2、4、6、8、10、12、14d after inoculation respectively.CT scans of each rabbit were retrospectively and independently assessed by two chest radiologists for the pattern of the pulmonary abnormalities(ground-glass attenuation(GGO),consolidation, nodules,reticular or linear opacity,thickening of the bronchovascular bundles,pleural effusion),and the distribution of the lesion(unilateral or bilateral;upper,middle or lower lung lobes;more than one lobe involved).Consensus was reached for disagreements.CT data were entered into a spreadsheet(Excel 2007,Microsoft).Statistical analysis was performed using the x~2 test and the Fisher's exact test,a P value of less than 0.05 was considered statistically significant.
【Results】
1,Thin-Section CT findings for each type of pneumonia
The CT manifestations were variable in neutropenic rabbits with C albicans pneumonia,consolidation(10/14) and ground-glass attenuation(8/14) were the most common findings,bronchovascular bundle thickening(3/14),nodule(2/14),and reticular or linear opacity(1/14) followed.Bilateral lung involvement was demonstrated in four cases.
GGO(11/15) and consolidation(9/15) were the most common findings in neutropenic rabbits with A fumigates pneumonia.Bronchovascular bundle thickening was seen in four rabbits,and reticular or linear opacity was seen in two.Bilateral lung involvement was seen in nine cases,but nodules were not observed in any case with A fumigates pneumonia.
16 rabbits had C neoformans pneumonia.14 of these cases had consolidation,and associated with ground-glass attenuation in 12 cases;ground-glass attenuation was seen in 13 cases.Three cases had bronchovascular bundle thickening,and nodular opacities, pneumothorax,reticular or linear opacity were respectively seen in one rabbit.Bilateral lung involvement was seen in about half of the patients with C neoformans pneumonia,
3、Comparison of Thin-Section CT Findings In brief,ground-glass attenuation and air-space consolidation were the most common findings in neutropenic rabbits with these three fungal pneumonias,and occasionally associated with bronchovascular bundle thickening,nodules and reticular or linear opacity. There was no stastistically significant difference in the prevalence of these CT patterns.
4、Comparison of frequency of Lobe Involvement
Although the presence of pulmonary lesion in middle lobes was higher in rabbits with A fumigates pneumonia and C neoformans pneumonia than in that with C albicans pneumonia,the difference was not statistically significant The frequency of involvement in other lobes and the frequency of involvement in more than one lobe were not statistically different between the three kinds of pneumonia.
【Conclusion】
C albicans pneumonia demonstrates a wide spectrum of thin-section CT findings that are similar to those of A fumigates and C neoformans;ground-glass attenuation and air-space consolidation are the most common findings,and usually associated with other findings,including bronchovascular bundle thickening,nodules and reticular or linear opacity;the difference of all the CT findings is not statistically significant.
Part Two Pulmonary infections after kidney transplantation:Analysis of CT appearance in 121 Patients
【Background】
Pulmonary infections are a common cause of morbidity and mortality after kidney transplantation.Pathogens include bacteria,fungi,virus,and so on.Early and accurate diagnosis is clinically important,but difficult.CT examination,especially thin-section CT and postprocessing Techniques may show pulmonary abnormalities in patients with normal findings on radiographs and is superior to radiography in depicting the pattern and extent of abnormalities.Several studies have described the thin-section CT manifestations of pulmonary infections in kidney transplant patients.These studied have been limited to a relatively small number of patients and have focused mainly on the description of specific infections,few information is available about CT features that may allow distinction among the various types of infections.
【Objective】
The purpose of this study was to review the CT findings in patients with pulmonary infection after kidney transplantation and to determine distinguishing features among various types of infection。
【Methods】
The patients were selected by a review of the medical records at our institution from May 2000 to February 2008 and came from a population Of 446 patients who had been proven pulmonary infection after kidney transplantation.We identified 121 patients who had undergone thin-section CT of the chest and proven diagnosis within 1 week of the CT scans.The Pulmonary infiltration was considered to be infectious when there was clinical suspicion of a lower respiratory tract infection,the.presence of radiologic findings,a microbial agent isolated in respiratory and/or nonrespiratory samples,or improvement after specific treatment.
Marconi MxS000(Siemens,Erlangen,Germany),Toshiba Aquilion(Toshiba Medical Systems,Tokyo,Japan),or Lightspeed VCT(General Electric Medical Systems, Milwaukee,WI) were used.The lungs were scanned at end-inspiration from the apex of the lung to the diaphragm.Postprocessing tools,including multiplanar reconstruction (MPR),maximum intensity projection(MIP) and minimum intensity projection(mIP),and volume rendering(VR),were used in some cases.The images were interpreted independently by two radiologists,who were blinded to the findings of other imaging modalities and the final diagnosis.The following CT findings were evaluated:pattern of the pulmonary abnormalities(GGO,reticular or linear opacity,air-space consolidation, nodules,tree-in-bud pattern,bronchovascular bundle thickening,pleural effusion,pleural thickening,and lymphadenopathy);distribution of the lesion(GGO,nodules,reticular or linear opacity).The clinical and CT data were entered into a spreadsheet(Excel 2007, Microsoft).Statistical analysis was performed using the x~2 test and the Fisher's exact test, a P value of less than 0.05 was considered statistically significant.
【Results】
一、Distributions of pulmonary infections in Kidney Transplant Recipients
1、Time distributions:The incidence of pulmonary infections almost the same from 2001 to 2006,and have obviously increase in 2007.July to august and February to march were the most common season for these patients.
2、Time Course:Pulmonary infections were diagnosed in 446 cases,which are more likely to occur in the time period between 2 and 4 months posttransplantation,with a peak incidence in the 3 months after the procedure.65(14.6%) episodes occurred in the first 30 days,147(32.9%) cases in the time period between 1 and 3 months,91(20.4%) cases between 3 and 6 months,23(5.2%) cases between 6 and 12 months,120(26.9%) cases after 12 months of transplantation,the mortality rate was 8.5%.In the first month after procedure,bacterial pathogens were predominately.One to 6 months following transplant, bacterial、virus(CMV) and mixed infection are seen commonly.After 12 months of transplantation,bacterial、virus(CMV) and mixed infection remains a concern but mycobacterial and fungal infections should be considered as potential causes for infiltrates.
The study group(121 cases) was composed of 28 females and 93 males who ranged in age from 14 to 71 years(mean age 42.7 years).Pulmonary infection Occured from 10 to 4522 days posttransplantation,7 episodes occurred in the first 30 days,36 cases in the time period between 1 and 3 months posttransplantation,19 cases in the time period between 3 and 6 months posttransplantation,8 cases between 6 and 12 months posttransplantation, 51 cases after 12 months of transplantation.
3、Infectious Etiologies:In the 121 patients enrolled as having pneumonia,89 patients had a definite etiologic diagnosis.Bacterial(28%) and mixed infections(28%) were the most common causes of pneumonia,followed by fungi(7%),TB(6%) and CMV(4%). More than 2/3rd of pulmonary infections in kidney transplant recipients can be attributed to bacterial organisms,Staphylococcus,Streptococcus pneumonia,and Gram-negative bacilli were the most common bacterial pathogens.All the virus pneumonia was caused by CMV.Candida albicans and Aspergillus were the most common fungal pathogens.
二、CT Appearance in Kidney Transplant Recipients
1,CT findings of the various infections
Pulmonary tuberculosis was diagnosed in 7 patients,and abnormalities were shown in 6 patients.Tree-in-bud pattem(n=4) was the most common finding in these patients.Small nodules were seen in 4 patients,GGO was seen in three patients,consolidation was seen in two,pleural effusion was seen in three,reticular or linear opacity in two,and mediastinal lymphadenopathy in one.
34 cases had bacterial pneumonia.24 of these patients had GGO,twenty of which were diffuse,and four,focal.23 cases had nodular opacities,including 14 patients with centrilobular nodules and nine with random nodules;22 patients with small nodules and one with large nodules;One surround by halo sign.Reticular or linear opacity was seen in 20 patients,seventeen of which were diffuse,and three,patchy.Reticular or linear opacity was involved mainly the lower lung zone in 16 patients,associated with ground-glass attenuation in 11 cases;with consolidation in 4 cases,and both in five.Consolidation was seen in 11 patients and involved mainly the lower lung zone.
CMV pneumonia:all 5 patients with CMV pneumonia had abnormal findings on CT scans.GGO was seen in 4 of 5 patients.These areas were all diffuse.In all four cases, ground-glass attenuation was associated with other abnormalities,including reticular or linear opacity(n=2),small nodules(n=2).Reticular or linear opacity were identified in 3 of 5 patients.These areas were all diffuse too.Multiple nodules were identified in 2 of 5 patients.All nodules were smaller than 10mm in diameter.Overall,the major of 5 patients with CMV pneumonia and 12 patients with mixed CMV pneumonia had GGO combined with reticular or linear opacity,nodules,tree-in-bud patterns.
Fungal pneumonia:Reticular or linear opacity was the most common finding in these nine patients and associated with ground-glass opacities in two cases.GGO was seen in three patients,diffuse in two cases and focal in one.four cases had nodular opacities.Two large nodules surrounded by halo sign were seen in one patient with Aspergillus organisms. Air-space consolidation was seen in two patients,pleural thickening was seen in six patients,thickening of the bronchovascular bundle was seen in four patients,and tree-in-bud pattern was seen in two.
For mixed infections,the CT manifestations were variable,which consisted of reticular or linear opacity,GGO,nodules,consolidation,pleural effusion,thickening of the bronchovascular bundles,or a combination of these patterns.
2,comparison of the CT findings of the various infections
Tree-in-bud pattern was seen in 4 of 7 patients with tuberculosis,5 of 34 patients with bacterial pneumonia,2 of 9 patients with fungal pneumonia,2 of 5 patients with CMV pneumonia,1 of 34 patients with mixed infections.Tree-in-bud pattern(P=0.049) was significantly more frequent in patients with tuberculosis than in those with bacterial pneumonia.
GGO was present in 24 of 34 patients with bacterial pneumonia,diffuse in 20 cases and focal in four.4 of 5 patients with CMV pneumonia and 3 of 9 patients with fungal pneumonia were diffuse.20 of 34 patients with mixed infection,diffuse in 17 cases and focal in three.3 of 7 patients with pulmonary tuberculosis,diffuse in one case and focal in two.
Nodules were present in 23 of 34 patients with bacterial pneumonia,centrilobular in 14 cases and random in 9.4 of 7 patients with pulmonary tuberculosis,centrilobular in three cases and random in one.19 of 34 patients with mixed infection,random in 13 cases.4 of 9 patients had fungal pneumonia.2 of 5 patients had CMV pneumonia.
Reticular or linear opacity was present in 23 of 34 patients with mixed infection, diffuse in 20 cases and focal in three.3 of 5 patients with CMV pneumonia and 6 of 9 patients with fungal pneumonia were all diffuse.20 of 34 patients had bacterial pneumonia, diffuse in 17 and focal in 3.3 of 7 patients had tuberculosis.
Air-space consolidation was present in 2 of 7 patients with tuberculosis and 2 of 9 patients with fungal pneumonia,11 of 34 patients with bacterial pneumonia,focal in 8 cases and multifocal in three,patchy in seven and Segmental in three.7 of 34 patients with mixed infection,focal in one case and multifocal in seven,patchy in five cases and Segmental in five.Consolidation was not present in patient with CMV pneumonia.
There was no stastistically significant difference in the prevalence of the CT patterns including GGO,reticular or linear opacity,nodules,air-space consolidation,pleural effusion,bronchovascular bundle thickening,Tree-in-bud pattern,and pleural thickening, among tuberculosis,bacterial,viral,fungal,mixed infections(all P＞0.05).
【Conclusion】
Our study shows that bacterial infection is the commonest cause of post kidney transplant pulmonary infection and more than 1/4rd of pulmonary infections can be attributed to multiple organisms.Pulmonary infections are more likely to occur in the time period between 2 and 4 months posttransplantation,with a peak incidence in the 3 months. In the first month after procedure,bacterial pathogens were predominately.One to 6 months following transplant,bacterial,virus(CMV) and mixed infection are commonly observed.After 12 months of transplantation,bacterial、virus(CMV) pneumonia and mixed infection remains a concern but mycobacterial and fungal infections should be considered as potential causes for infiltrates.The CT manifestations consist of reticular or linear opacity,GGO,nodules,consolidation,pleural effusion,bronchovascular bundle thickening,or a combination of these patterns;Tree-in-bud pattern were significantly more frequent in patients with tuberculosis than in those with bacterial pneumonia.Other CT patters are not helpful in distinguish among the various types of infection seen in kidney transplant recipients.The presence of large nodules surrounded by halo sign is most suggestive of Aspergillus infection.MDCT angiography has been shown to be a feasible technique to depict directly vessel occlusion in the setting of suspected fungal infections, especially for early diagnosis of angioinvasive pulmonary Aspergillosis in renal transplant recipients.Ground-glass attenuation is commonly seen in CMV pneumonia,and Reticular or linear opacity is common observed in fungal infection.Air-space consolidation is relatively common seen in bacterial,fungal and mixed pneumonia than other pathogens. Segmental consolidation in posterior of lower lung zone may gradually vanished by reversion to linear opacity,GGO.Pleural thickening is a valuable sign to judge the pulmonary infection.MDCT allows contiguous visualization of the lung parenchyma,the blood vessels and the airways.Postprocessing tools,including MPR,MIP,mIP,and VR, are used to help quantify the various patterns(MIP permits the detection and characterization of micronodules and tree-in-bud pattern;quantification the extent of air-space consolidation),assess the distribution and extent of these signs to help differentiate different type infections.
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75.Reichenberger F,Habicht JM,Gratwohl A,et al.Diagnosis and treatment of invasive pulmonary aspergillosis in neutropenic patients[J].Eur Respir,2001,19(1):743-755.
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82. Lee SA. A Review of Pneumocystis Pneumonia[J]. J Pharm Pract, 2006, 19(2): 5-9.
83. Hoang LMN, Maguire JA, Matthay R, et al. Cryptococcus neoformans infections at Vancouver Hospital and Health Sciences Centre (1997 - 2002): epidemiology, microbiology and histopathology[J]. Med. Microbiol, 2004, 53(9): 935-940.
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86. Lee FYW, Mossad SB, Adal KA. Pulmonary Mucormycosis: The Last 30 Years[J]. Arch Intern Med, 1999,159:1301 - 1309.
87. Spellberg B, Edwar J, Ibrahim A. Novel Perspectives on Mucormycosis: Pathophysiology, Presentation, and Management[J]. Clin Microbiol Rev, 2005, 18(7): 556-569.
88. Vogl TJ, Hinrichs T, Jacobi V, et al. Computed tomographic appearance of pulmonary mucormycosis[J]. Rofo, 2000, 172(7): 604-608.
89. Carol A. Kauffman. Fungal Infections [J]. Proc Am Thorac Soc, 2006, 3:35-40.