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ORIGINAL ARTICLE
Year : 2019  |  Volume : 21  |  Issue : 1  |  Page : 57-62

Correlation between the probability of malignancy and maximum standard uptake values of mediastinal lymph nodes on 18F-FDG positron emission tomography scan sampled by endobronchial ultrasound-guided-transbronchial needle aspiration:A retrospective analysis


University of Health Sciences Dr. Suat Seren Chest Diseases and Surgery Education and Training Hospital, Izmir, Turkey

Date of Submission17-Dec-2017
Date of Decision07-Apr-2018
Date of Acceptance02-May-2018
Date of Web Publication30-Apr-2019

Correspondence Address:
Yelda Varol
University of Health Sciences Dr. Suat Seren Chest Diseases and Surgery Education and Training Hospital, Izmir
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ejop.ejop_64_18

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  Abstract 


INTRODUCTION: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is frequently used as an important initial investigation for diagnosing and staging for both suspected malignant and benign mediastinal lesions for the last 10 years.
AIM: We aimed to analyze the correlation between probability of malignity by EBUS-TBNA and maximum standard uptake value (SUVmax) obtained by 18F-labeled fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET CT).
METHODS: This is a retrospective study using hospitals' database records. Demographic features of the patients, characteristics of the biopsied lymph nodes (LNs), PET-CT results, and SUVmax are obtained from hospital database system.
RESULTS: A total of 322 patients underwent EBUS-TBNA for a final diagnosis. The mean age was 59.4 years. The most common final diagnosis was nonsmall cell lung cancer. When we compared the average SUVmax, as the SUVmax increased, the probability of malignity increased significantly (P < 0.001). We studied a Youden index for SUVmax and the cutoff point for SUVmax was 9 for 54.39% sensitivity and 79.1% specificity.
CONCLUSION: Our study in a real-life setting showed that EBUS-TBNA is effective in diagnosing patients who had mediastinal LNs suspected of malignancy. We also showed that as the SUVmax increased, the probability of malignancy increased. We believe that more data are needed from a larger number of patients from different centers.

Keywords: Endobronchial ultrasound, lung cancer, positron emission tomography-computed tomography, staging


How to cite this article:
Cirak AK, Deniz S, Varol Y, Vayisoglu G, Tekgül S, Alizoroglu D, Yalniz E. Correlation between the probability of malignancy and maximum standard uptake values of mediastinal lymph nodes on 18F-FDG positron emission tomography scan sampled by endobronchial ultrasound-guided-transbronchial needle aspiration:A retrospective analysis. Eurasian J Pulmonol 2019;21:57-62

How to cite this URL:
Cirak AK, Deniz S, Varol Y, Vayisoglu G, Tekgül S, Alizoroglu D, Yalniz E. Correlation between the probability of malignancy and maximum standard uptake values of mediastinal lymph nodes on 18F-FDG positron emission tomography scan sampled by endobronchial ultrasound-guided-transbronchial needle aspiration:A retrospective analysis. Eurasian J Pulmonol [serial online] 2019 [cited 2019 Sep 19];21:57-62. Available from: http://www.eurasianjpulmonol.com/text.asp?2019/21/1/57/257455




  Introduction Top


Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is usually used as an important first choice investigation for diagnosing suspected malignant and benign mediastinal lesions.[1],[2] The diagnostic yield of EBUS-TBNA for the detection of malignity for mediastinal enlargements has sensitivity between 88% and 93%.[3] There are some studies examining the relationship between EBUS-TBNA diagnostic utility and computed tomography (CT) staging, positron emission tomography-CT (PET-CT) node maximum standard uptake value (SUVmax), and node size calculated by EBUS.[2],[4]

Although the size of lymph nodes (LNs) has been shown to be an important predictor of LN metastases, EBUS-TBNA had a sensitivity of 35%, a negative predictive value of 88%, and an accuracy of 88%, in particular small nodes below 10 mm in size.[4],[5] Further, as shown in literature, PET scanning for mediastinal staging of lung cancer only has 74% sensitivity and 85% specificity.[6]

Therefore, the aim of our study was to plan a retrospective analysis of EBUS-TBNA in a real-life setting in patients whom were referred with suspected mediastinal lesions to a Chest Diseases Hospital containing an EBUS-TBNA center between December 1, 2012, and January 1, 2016. We aimed to analyze the correlation between probability of malignity by EBUS-TBNA and SUVmax obtained by 18F-labeled fluorodeoxyglucose (18F-FDG) PET CT.


  Methods Top


Subject selection

A retrospective analysis of 322 consecutive EBUS-TBNA patients whom were referred to our hospital between December 1, 2012, and January 1, 2016, was performed. Cases were referred for the diagnosis of mediastinal LN enlargements detected on CT scanning. Cases also referred for nodes with an elevated SUVmax on PET scanning in which there was a suspicion of malignity based on radiological assessment. All cases of lung cancer, including nonsmall and small cell lung cancer (NSCLC and SCLC) were included. The study was approved by the local institutional review board. The study had been approved by the Ethic Committee of our Hospital's Ethics Committee on November 11, 2017, and the protocol number was 49109414/806.02.02/7826. No written informed consent was taken from patients because of the study's retrospective design. Demographic data, if exists, sites of primary malignancies and tuberculosis (TB) history, CT and PET findings, EBUS findings, stations of aspirated LNs, cytological and histological findings, and final diagnoses were recorded and used from our database.

Radiological evaluation

As this is a real-life study and undergoing EBUS-TBNA was a part of the ongoing standard of care for patients, no specific radiological intervention was made to any patients. Therefore, not all the patients had undergone PET-CT. The indication of EBUS-TBNA in enrolled patients was an LN with a short-axis diameter of >10 mm on the thorax CT. Further, EBUS-TBNA was performed if the LNs had a high FDG uptake on PET-CT scans. PET-CT was performed according to the patients' routine oncological evaluation. The FDG uptake on PET-CT was considered positive if the SUVmax was ≥2.5.

The endobronchial ultrasound-guided transbronchial needle aspiration procedure

One trained primary operator in the endoscopy unit performed EBUS-TBNA with patients in supine position under conscious sedation (midazolam and fentanyl), through the oral route using a convex Probe Ultrasound Bronchoscope (7.5 MHz, BF-UC160F; Olympus Optical Co., Tokyo, Japan). The new international LN map proposed by the International Association for the Study of Lung Cancer was used to determine the LN stations.[7] If there are multiple suspected LNs, the decision of choosing the LN to puncture depends on the physician's judgment based on findings from the CT or PET-CT scans. Each target nodal station was punctured at least three times with a dedicated 22-gauge needle (NA-201SX-4022, Olympus). The aspirate was then blown onto a glass slide by pushing air using a 20-mL syringe. Aspirated material was also obtained for cell block and Mycobacterium and bacterial cultures.

Pathological examination

Some amount of the aspirate was smeared onto glass slides during the procedure; slides were air-dried and fixed immediately with 95% alcohol. They stained with hematoxylin and eosin. The rest of the aspirate was placed into a mixture of formalin and alcohol to obtain a cell block for histological examination.

Mycobacterial cultivation and identification

Fine-needle aspiration biopsy specimens were transported to the microbiology laboratory immediately. The samples were suspended in 1 mL of Middlebrook 7H9 medium and vortexed in the laboratory. The suspensions were then digested and decontaminated by Mycoprosafe (Salubris AS, Istanbul, Turkey) decontamination kit. Mycobacterial cultivation was performed by both MGIT 960 system (BD Biosciences, Sparks, MD, USA) according to the manufacturer's recommendations[8] and Lowenstein–Jensen slants (Salubris AS). An acid-fast smear preparation by Kinyoun staining was also applied to each processed specimen. Differentiation of Mycobacterium tuberculosis and nontuberculous mycobacteria was performed by both conventional methods[9] and BD immunochromatographic tests (BD Biosciences, Sparks, MD, USA). M. tuberculosis H37Ra was used as the control strain in all cultivation and identification methods.

Final diagnosis

The final diagnosis was obtained from our database. Patients had a diagnosis of malignity if EBUS-TBNA-aspirated materials contained malignant cells. Diagnosis of TB was made according to the following criteria: granulomatous inflammation and the presence of acid-fast bacilli on microscopy or a positive culture for M. tuberculosis. Diagnosis of sarcoidosis was considered according to these three criteria: compatible clinical and radiographic manifestations, exclusion of other diseases that may present similarly, histopathologic detection of noncaseating granulomas.

Statistical analysis

Data were analyzed with MedCalc software version 12.7.7 (MedCalc Software bvba, Ostend, Belgium; http://www.medcalc.org; 2013). The mean, standard deviation, median, minimum value, and maximum values of the continuous variables were given. Since continuous variables were not the normally distributed, it was performed by nonparametric tests. Mann–Whitney U-test was used in independent groups. Nominal variables were presented with their frequencies and percentages. Receiver operating characteristic (ROC) curve was used for the determination of cutoff value for obtaining the best sensitivity and specificity of SUVmax between benign and malign lesions. The level of statistical significance was determined as P < 0.05.


  Results Top


In our study, 322 patients underwent EBUS-TBNA for a final diagnosis. There was a male preponderance (230, 71.4%), with an average age of 59 years (range 16–86). Of the 322 patients referred, 182 were subsequently diagnosed with lung cancer (56.4%): 33 (10.2%) SCLC and 149 (46.2%) NSCLC, and 18 (5.5%) extra thoracic cancer [Table 1]. 59 (18.3%) patients were diagnosed with sarcoidosis and 9 (2.7%) with TB. Fifty-one patients either had a diagnosis of reactive LN or anthrocosic LNs. Three patients could not have a diagnosis with EBUS-TBNA alone but needed mediastinoscopy.
Table 1: The distribution of final diagnosis obtained by endobronchial ultrasound-guided transbronchial needle aspiration

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A total of 511 nodal stations were sampled in benign lesions. The nodal stations sampled were 2R, 2 L, 4R, 4 L, 7, 10, and 11. A total of 191 nodal stations were sampled in malignant lesions. The nodal stations sampled were 4R, 4 L, 7, 10 and 11. In both benign and malignant groups, the most frequent biopsied station was 7. The distribution of LN stations according to malignity is summarized in [Table 2]. Of the 182 NSCLC patients, 65 patients diagnosed as lung adenocarcinomas, 67 squamous cell carcinoma, and 17 without differentiation. Majority of the cancer patients were stage 4 [Table 1]. A total of 124 LNs which are punctured by EBUS-TBNA have a SUVmax. Fifty-seven of the malignant lesions and 67 of the benign lesions which are proven by EBUS-TBNA cytology have a SUVmax.
Table 2: The distribution of the malignant and benign lymph nodes according to the lymph node map stations

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According to the PET-CT SUVmax, the highest SUVmax was in the station 10 [Table 3]. The average median SUVmax for benign lesions was 5.6 (2.4–23.4), and the average median SUVmax for malignant lesions was 9.5 (3–38.2) [Table 4]. When we compared the average SUVmax, as the SUVmax increased, the probability of malignity increased significantly (P < 0.001). When we made an ROC curve, the predictive value was 68% for EBUS-TBNA (P < 0.05) [Figure 1]. This value is the power of determining the malignity in the whole LNs which are punctured and also have SUVmax in study population. We studied a Youden index for SUVmax and this index determined the SUVmax as 9 for 54.39% sensitivity and 79.1% specificity. The SUVmax is correlated with the diagnosis.
Table 3: The average maximum standard uptake values according to the lymph nodes biopsied by endobronchial ultrasound-guided transbronchial needle aspiration

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Table 4: The average maximum standard uptake values of the benign and malignant lymph nodes punctured by endobronchial ultrasound guided transbronchial needle aspiration

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Figure 1: The median maximum standard uptake values of the benign and malignant lymph nodes

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  Discussion Top


Our study showed that EBUS-TBNA is frequently used to confirm the diagnosis in patients which have suspected mediastinal LN enlargements, avoiding unnecessary invasive techniques in the majority of the cases. None of our patients required overnight admission. This finding supports the study demonstrating that EBUS-TBNA is well tolerated under conscious sedation in outpatient clinics.[10] Further, we showed that as the SUVmax increased, the probability of malignity increased significantly.

EBUS-TBNA for diagnosis of malignity in the mediastinal nodes is a very effective, and this technique has low (about 1%) rate of complications.[11],[12],[13],[14],[15] In diagnosing and staging of NSCLC, reports from different centers show considerable variation of EBUS-TBNA diagnostic utility (71%–99%),[15],[16],[17],[18],[19] with sensitivity (46%–97%) and negative predictive value (60%–99%).[20] Further, in patients previously treated with neoadjuvant therapy, EBUS-TBNA has a high diagnostic accuracy rate.[21] In our study, only three patients needed mediastinoscopy for diagnosis. 56.4% of the cases diagnosed and staged by EBUS-TBNA not requiring invasive techniques. Majority of our cases were NSCLC as expected. Further, in 18 cases, metastasis from extrathoracic malignity to mediastinal LNs was obtained by EBUS-TBNA without difficulty.

Patients with a diagnosis of granulomatous inflammation by pathology were often being prescribed diagnostic anti-TB therapy due to the prevalence of TB.[22],[23] However, after anti-TB treatment, such patients should clinically improve. It should also be kept in mind that there is different final diagnosis with granulomatous inflammation obtained by EBUS-TBNA. TB is most common cause of infectious granulomas, but it is not the only reason. In our study, nine patients had a diagnosis of TB according to the following criteria: granulomatous inflammation and the presence of acid-fast bacilli on microscopy, or a positive culture for M. tuberculosis.

In our study, the average median SUVmax for benign lesions was 5.6, and the average median SUVmax for malignant lesions was 9.5. These findings show that benign lesions could also have high SUVmax as expected. However, when we compared the average SUVmax, as the SUVmax increased, the probability of malignity increased significantly. In addition, when we made an ROC curve comparing the probability of malignity and SUVmax, the predictive value was 68%. A value of 9 for SUVmax was determined for 54.39% sensitivity and 79.1% specificity.

There were studies showing that EBUS-TBNA may be helpful in determining lymphoma with a sensitivity range from 76% to 90.9%; however, new studies showed that reactive LN diagnosed by EBUS-TBNA may have a final diagnosis as lymphoma by thoracotomy.[24],[25],[26] More biopsy specimens, using flow cytometry and immunohistology, may help increase the diagnostic utility of EBUS-TBNA for lymphoma. In our study, although we use cell blocks during the EBUS-TBNA which can increase the diagnostic utility of the procedure, none of the patients diagnosed as lymphoma by EBUS-TBNA.[27]

The limitations of our study are its observational, single–center, and retrospective study design. Cases which diagnosed malignant with EBUS-TBNA were not confirmed by invasive surgical sampling. However, as this is a real-life study, in the literature, false-positive malignity results have rarely been observed following TBNA and EBUS-TBNA.[28],[29],[30] Not all the patients had PET-CT results and the number of PET-CT nodal SUVmax data was limited by incomplete reporting and lack of availability of all PET scans which were performed in different centers.


  Conclusion Top


Our study in a real-life setting showed that EBUS-TBNA is safe and effective in diagnosing patients who had mediastinal LNs suspected of malignity. We also showed that as the SUVmax increased, the probability of malignity increased. We believe that more data are needed from a larger number of patients from different centers.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Medford AR, Bennett JA, Free CM, Agrawal S. Mediastinal staging procedures in lung cancer: EBUS, TBNA and mediastinoscopy. Curr Opin Pulm Med 2009;15:334-42.  Back to cited text no. 1
    
2.
Medford AR, Bennett JA, Free CM, Agrawal S. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA): Applications in chest disease. Respirology 2010;15:71-9.  Back to cited text no. 2
    
3.
Low A, Medford AR. Endobronchial ultrasound-guided transbronchial needle aspiration. Rev Recent Clin Trials 2013;8:61-71.  Back to cited text no. 3
    
4.
Wang L, Wu W, Hu Y, Teng J, Zhong R, Han B, et al. Sonographic features of endobronchial ultrasonography predict intrathoracic lymph node metastasis in lung cancer patients. Ann Thorac Surg 2015;100:1203-9.  Back to cited text no. 4
    
5.
Shingyoji M, Nakajima T, Yoshino M, Yoshida Y, Ashinuma H, Itakura M, et al. Endobronchial ultrasonography for positron emission tomography and computed tomography-negative lymph node staging in non-small cell lung cancer. Ann Thorac Surg 2014;98:1762-7.  Back to cited text no. 5
    
6.
Silvestri GA, Gould MK, Margolis ML, Tanoue LT, McCrory D, Toloza E, et al. Noninvasive staging of non-small cell lung cancer: ACCP evidenced-based clinical practice guidelines (2nd edition). Chest 2007;132:178S-201S.  Back to cited text no. 6
    
7.
Goldstraw P, Crowley J, Chansky K, Giroux DJ, Groome PA, Rami-Porta R, et al. The IASLC lung cancer staging project: Proposals for the revision of the TNM stage groupings in the forthcoming (seventh) edition of the TNM classification of malignant tumours. J Thorac Oncol 2007;2:706-14.  Back to cited text no. 7
    
8.
Tortoli E, Cichero P, Piersimoni C, Simonetti MT, Gesu G, Nista D, et al. Use of BACTEC MGIT 960 for recovery of mycobacteria from clinical specimens: Multicenter study. J Clin Microbiol 1999;37:3578-82.  Back to cited text no. 8
    
9.
Koneman EW, Allen SD, Janda WM, Schreckenberger PC, Winn WC. Mycobacteria. In: Color Atlas and Textbook of Diagnostic Microbiology. 4th ed. Philadelphia, PA, USA: J. B. Lippincott Company; 1992. p. 703-55.  Back to cited text no. 9
    
10.
Jeyabalan A, Medford AR. Endobronchial ultrasound-guided transbronchial needle aspiration: Patient satisfaction under light conscious sedation. Respiration 2014;88:244-50.  Back to cited text no. 10
    
11.
Eapen GA, Shah AM, Lei X, Jimenez CA, Morice RC, Yarmus L, et al. Complications, consequences, and practice patterns of endobronchial ultrasound-guided transbronchial needle aspiration: Results of the AQuIRE registry. Chest 2013;143:1044-53.  Back to cited text no. 11
    
12.
Gu P, Zhao YZ, Jiang LY, Zhang W, Xin Y, Han BH, et al. Endobronchial ultrasound-guided transbronchial needle aspiration for staging of lung cancer: A systematic review and meta-analysis. Eur J Cancer 2009;45:1389-96.  Back to cited text no. 12
    
13.
Varela-Lema L, Fernández-Villar A, Ruano-Ravina A. Effectiveness and safety of endobronchial ultrasound-transbronchial needle aspiration: A systematic review. Eur Respir J 2009;33:1156-64.  Back to cited text no. 13
    
14.
Micames CG, McCrory DC, Pavey DA, Jowell PS, Gress FG. Endoscopic ultrasound-guided fine-needle aspiration for non-small cell lung cancer staging: A systematic review and metaanalysis. Chest 2007;131:539-48.  Back to cited text no. 14
    
15.
Lee BE, Kletsman E, Rutledge JR, Korst RJ. Utility of endobronchial ultrasound-guided mediastinal lymph node biopsy in patients with non-small cell lung cancer. J Thorac Cardiovasc Surg 2012;143:585-90.  Back to cited text no. 15
    
16.
Yasufuku K, Pierre A, Darling G, de Perrot M, Waddell T, Johnston M, et al. Aprospective controlled trial of endobronchial ultrasound-guided transbronchial needle aspiration compared with mediastinoscopy for mediastinal lymph node staging of lung cancer. J Thorac Cardiovasc Surg 2011;142:1393-400.e1.  Back to cited text no. 16
    
17.
Tian Q, Chen LA, Wang RT, Yang Z, An Y. The reasons of false negative results of endobronchial ultrasound-guided transbronchial needle aspiration in the diagnosis of intrapulmonary and mediastinal malignancy. Thorac Cancer 2013;4:186-90.  Back to cited text no. 17
    
18.
Nakajima T, Yasufuku K, Saegusa F, Fujiwara T, Sakairi Y, Hiroshima K, et al. Rapid on-site cytologic evaluation during endobronchial ultrasound-guided transbronchial needle aspiration for nodal staging in patients with lung cancer. Ann Thorac Surg 2013;95:1695-9.  Back to cited text no. 18
    
19.
Figueiredo VR, Cardoso PF, Jacomelli M, Demarzo SE, Palomino AL, Rodrigues AJ, et al. Endobronchial ultrasound-guided transbronchial needle aspiration for lung cancer staging: Early experience in Brazil. J Bras Pneumol 2015;41:23-30.  Back to cited text no. 19
    
20.
Silvestri GA, Gonzalez AV, Jantz MA, Margolis ML, Gould MK, Tanoue LT, et al. Methods for staging non-small cell lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest 2013;143:e211S-50S.  Back to cited text no. 20
    
21.
Cetinkaya E, Usluer O, Yılmaz A, Tutar N, Çam E, Özgül MA, et al. Is endobronchial ultrasound-guided transbronchial needle aspiration an effective diagnostic procedure in restaging of non-small cell lung cancer patients? Endosc Ultrasound 2017;6:162-7.  Back to cited text no. 21
[PUBMED]  [Full text]  
22.
Sun J, Teng J, Yang H, Li Z, Zhang J, Zhao H, et al. Endobronchial ultrasound-guided transbronchial needle aspiration in diagnosing intrathoracic tuberculosis. Ann Thorac Surg 2013;96:2021-7.  Back to cited text no. 22
    
23.
Ministry of Health. Bureau of Disease Control and Prevention, Bureau of Medical Administration, Chinese Center for Disease Control and Prevention. Chinese Tuberculosis Control Program Implementation Guidance. Beijing: Peking Union Medical College Press; 2009. p. 1.  Back to cited text no. 23
    
24.
Kheir F, Itani A, Assasa O, Alraiyes AH. The utility of endobronchial ultrasound-transbronchial needle aspiration in lymphoma. Endosc Ultrasound 2016;5:43-8.  Back to cited text no. 24
[PUBMED]  [Full text]  
25.
Steinfort DP, Conron M, Tsui A, Pasricha SR, Renwick WE, Antippa P, et al. Endobronchial ultrasound-guided transbronchial needle aspiration for the evaluation of suspected lymphoma. J Thorac Oncol 2010;5:804-9.  Back to cited text no. 25
    
26.
Marshall CB, Jacob B, Patel S, Sneige N, Jimenez CA, Morice RC, et al. The utility of endobronchial ultrasound-guided transbronchial needle aspiration biopsy in the diagnosis of mediastinal lymphoproliferative disorders. Cancer Cytopathol 2011;119:118-26.  Back to cited text no. 26
    
27.
Demirci NY, Dikmen AU, Abdullayeva Z, Öztürk C. Contribution of cell blocks obtained through endobronchial ultrasound-guided transbronchial needle aspiration for the determination of lung cancer subtypes. Clin Respir J 2018;12:1623-7.  Back to cited text no. 27
    
28.
Cropp AJ, DiMarco AF, Lankerani M. False-positive transbronchial needle aspiration in bronchogenic carcinoma. Chest 1984;85:696-7.  Back to cited text no. 28
    
29.
Schenk DA, Chasen MH, McCarthy MJ, Duncan CA, Christian CA. Potential false positive mediastinal transbronchial needle aspiration in bronchogenic carcinoma. Chest 1984;86:649-50.  Back to cited text no. 29
    
30.
Sanz-Santos J, Andreo F, Serra P, Llatjós M, Castellà E, Astudillo J, et al. False positive endobronchial ultrasound-guided real-time transbronchial needle aspiration secondary to bronchial carcinoma in situ at the point of puncture: A case report. J Cardiothorac Surg 2012;7:74.  Back to cited text no. 30
    


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