Published online before print June 13, 2002, 10.1148/radiol.2242011424
(Radiology 2002;224:603-608.)
© RSNA, 2002
Peripheral Pulmonary Diseases: Evaluation with Endobronchial US— Initial Experience1
Shigenari Omori, MD,
Yuichi Takiguchi, MD, PhD,
Kenzo Hiroshima, MD, PhD,
Nobuhiro Tanabe, MD, PhD,
Koichiro Tatsumi, MD, PhD,
Hiroshi Kimura, MD, PhD2,
Keiichi Nagao, MD, PhD and
Takayuki Kuriyama, MD, PhD
1 From the Department of Respirology (B2), Graduate School of Medicine, (S.O., Y.T., N.T., K.T., H.K., T.K.), Department of Basic Pathology (B3), Graduate School of Medicine, (K.H.), and Health Sciences Center (K.N.), Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba 260-8670, Japan. Received August 24, 2001; revision requested October 11; revision received November 21; accepted January 7, 2002. Supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan. Address correspondence to Y.T. (e-mail: yuichi@med.m.chiba-u.ac.jp).
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ABSTRACT
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Endobronchial ultrasonography (US) with 4.5-F small-caliber US probes, combined with bronchoalveolar lavage technique, was evaluated in autopsied lungs and 22 patients with various pulmonary interstitial or alveolar diseases. Several different echoic patterns were found that may reflect changes due to pathologic alteration of lung parenchyma. This technique may have potential for evaluation and diagnosis of peripheral lung diseases.
© RSNA, 2002
Index terms: Lung, diseases, 60.203, 60.22, 60.323, 60.791, 60.792 • Lung, interstitial disease, 60.213 • Lung, US, 60.12981 • Ultrasound (US), endoscopic, 60.12981
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INTRODUCTION
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Ultrasonographic (US) examinations for thoracic diseases are divided into two approaches: percutaneous and endoscopic. Well-documented diseases and conditions for which conventional percutaneous US is useful for evaluation and diagnosis include mediastinal tumor (1), pleural effusion (2), pulmonary consolidation (3,4), pulmonary tuberculosis (5), and tumor invasion of the pleura or chest wall (6,7). Pulmonary lesions, including lung cancers not adjacent to the chest wall, however, have never been successfully investigated with US, to our knowledge, because lung tissue contains a large amount of air, which reflects virtually all the sound energy from the first sound-tissue interface, precluding penetration and, thus, imaging of the lung parenchyma. Therefore, clinical application of percutaneous US for thoracic diseases has been limited to lesions adjacent to the chest wall or diaphragm.
The earlier development of endoscopic US was combined with the gastroscope. Then, this technique was combined with the bronchoscope, which has expanded the clinical relevance of US to evaluation and guidance for fine-needle aspiration of mediastinal or hilar lymph nodes (8–11). In addition, the recently developed small-caliber US probes have enabled extension of the clinical use of US to tracheal and bronchial lesions. Guided by a fiberoptic bronchoscope, a small-caliber probe can be successfully introduced into the trachea and bronchus for assessment and diagnosis of endobronchial lesions or tumor metastasis to mediastinal or hilar lymph nodes. This procedure is sometimes combined with echo-guided fine-needle aspiration (12–19). This combined procedure was then further applied to the diagnosis of peripherally located nodular lung lesions (14).
Despite these improvements, the pulmonary parenchyma has never been an object of study with US, to our knowledge, because of its air content, except for some specific conditions such as atelectatic lung or pulmonary consolidation (3,4), in which air does not exist. The aim of the present study was to evaluate visualization of diffuse or localized peripheral pulmonary lesions by combining endobronchial US with bronchoalveolar lavage (BAL).
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Materials and Methods
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Our study was carried out in two stages: an initial in vitro stage and subsequent clinical experience.
In Vitro: Sponges and Autopsied Lungs
To examine the possibility that small-caliber US probes could make diagnostic images of human alveoli, a plastic sponge and a vegetable sponge were first imaged (Fig 1). On the basis of visual inspection of the images of air-filled sponges, the approximate sizes of the majority of the pores in the plastic sponge and vegetable sponge were from 100 to 200 µm and from 0.5 to 5 mm, respectively.
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Figure 1a. Macroscopic close-up view of (a, b) sponges and (c, d) their US images. The sponges were soaked in water to expel the air. The plastic sponge (a) and vegetable sponge (b) were distinctly different with respect to their pore size. The resultant US images of the plastic sponge (c) and vegetable sponge (d) displayed different echoic patterns. The bars in a-d represent 1 mm.
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Figure 1b. Macroscopic close-up view of (a, b) sponges and (c, d) their US images. The sponges were soaked in water to expel the air. The plastic sponge (a) and vegetable sponge (b) were distinctly different with respect to their pore size. The resultant US images of the plastic sponge (c) and vegetable sponge (d) displayed different echoic patterns. The bars in a-d represent 1 mm.
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Figure 1c. Macroscopic close-up view of (a, b) sponges and (c, d) their US images. The sponges were soaked in water to expel the air. The plastic sponge (a) and vegetable sponge (b) were distinctly different with respect to their pore size. The resultant US images of the plastic sponge (c) and vegetable sponge (d) displayed different echoic patterns. The bars in a-d represent 1 mm.
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Figure 1d. Macroscopic close-up view of (a, b) sponges and (c, d) their US images. The sponges were soaked in water to expel the air. The plastic sponge (a) and vegetable sponge (b) were distinctly different with respect to their pore size. The resultant US images of the plastic sponge (c) and vegetable sponge (d) displayed different echoic patterns. The bars in a-d represent 1 mm.
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Formalin-fixed approximately 1-cm-thick slices of autopsied lungs were also imaged. The lung slices had been soaked in formalin until the examinations. The specimens consisted of autopsied lungs from two patients with normal lung, two patients with pulmonary emphysema, and two patients with marked honeycomb lesions due to interstitial pneumonia.
Patients
Twenty-two patients (eight men and 14 women; age range, 25–70 years; mean age, 51 years) with diffuse or localized infiltrative pulmonary lesions who required evaluation with BAL gave their written informed consent to participate in this study. This study complied fully with institutional regulations. Final diagnoses for these patients were obtained by means of complete clinical evaluation, including clinical history; extensive serologic and immunologic examinations, such as measurements of immunoglobulins, C-reactive protein, and autoantibodies; BAL; fluoroscopy-guided transbronchial lung biopsy in all cases; and video-assisted thoracotomy biopsy when necessary. The patients and their diagnoses are listed in Table 1.
Equipment and Techniques
The US system (SSD-550; Aloka, Tokyo, Japan), equipped with a 4.5-F intravascular echo sensor (MP-PN-06L; Aloka) that is covered with a sterile water-filled 6-F sheath tube (ST-06L; Aloka), was used throughout this study. The technical parameters of the system were determined in preliminary studies (data not shown) as follows: frequency, 20 MHz; gain, 30; sensitivity time control, 30; speed, 15 frames per second (high density); and contrast, high. Typical images were recorded with a film recorder.
For observation of the sponges and autopsied lungs, the materials were soaked in water (for the sponges) or normal saline (for the autopsied lungs), and the US probe was inserted into one of the tiny holes of the sponges or small bronchi of the autopsied lung slices. For microscopic examinations of the autopsied lungs, marking pins were inserted into the exact points where US images were evaluated to allow hematoxylin-eosin–stained slides to be made from the corresponding locations. Thus, one to three regions were examined in each autopsied lung slice.
For the 22 patients, bronchoscopic examinations were carried out under mild sedation and regional anesthesia according to the standard procedures of our department. The single-channel fiberoptic bronchoscope (BF type 30; Olympus, Tokyo, Japan) was used in this study because its forceps channel is wide enough for passage of the US probes. On completion of tracheobronchial inspection and routine BAL, which consisted of instillation of 150 mL of sterile normal saline in three fractions and recovery of as much fluid as possible after each fraction, an additional injection of 50 mL of saline followed by insertion of a small-caliber US probe through the same forceps channel and the same bronchus were performed. US images were recorded at two or three different points of the same bronchus, from a proximal to a distal portion. The location of the probe was monitored with fluoroscopy (Fig 2). This additional procedure after routine BAL usually lasted no more than several minutes in each case.
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Figure 2. Fluoroscopic image obtained during the endobronchial US procedure. A small-caliber US probe was guided through the forceps channel of a bronchoscope to reach a subpleural lung region. The circumjacent lung was radiopaque (arrows) because of the preceding BAL procedure.
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After US observation, the remaining saline was aspirated, and additional procedures such as transbronchial lung biopsy were performed according to the clinical indications. Chest computed tomography (CT) was performed with an electron-beam CT scanner (Somatom Plus 4; Siemens Medical Systems, Munich, Germany) with 10- or 2-mm collimation, depending on clinical indication, at 10-mm intervals. The CT scans were acquired and viewed at window settings of 1,500 HU for window width and -600 HU for window level. In all the patients, CT scans were obtained as part of the routine clinical treatment protocol of patients with diffuse or localized peripheral lung diseases at our institution.
All US observations in the sponges, autopsied lungs, and patients were carried out by one of two authors (S.O., Y.T.), both pulmonologists.
Image Analysis
The two reviewers evaluated the recorded images independently by means of visual inspection. If there were differences between the two, discussion between them was held to reach consensus results. In case of disagreement after the discussion, the opinion of S.O. overrode that of Y.T.. Thus, a final decision was made in all cases.
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Results
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US Evaluation of Sponges and Autopsied Lungs
US images of two different types of sponges, in terms of their pore size, demonstrated distinct echoic patterns (Fig 1). That is, the image of a plastic sponge revealed a relatively fine granular appearance, whereas that of a vegetable sponge revealed a coarse and patchy granular appearance.
The US images of the autopsied lungs with normal, emphysematous, and honeycomb structures also appeared different from each other, and specimens with similar pathologic findings always related to similar US images. Microscopic views of typical pathologic findings and their corresponding US images are presented (Fig 3). The image of the normal lung showed a relatively regular and fine granular hyperechoic pattern, that of the emphysematous lung demonstrated a relatively loose and coarse granular hyperechoic pattern, and that of the honeycomb lung displayed a gross patchy combination of hyper- and hypoechoic pattern. These three echoic patterns resembled the hematoxylin-eosin–stained histologic findings from regions close to the areas where the US images were obtained.
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Figure 3a. US images and their corresponding photomicrographs of autopsied lungs. The autopsied lungs were from patients with (a) normal, (b) emphysematous, and (c) honeycomb lung. The lungs were fixed in formalin before being cut into 1-cm-thick samples. The samples were removed from formalin and soaked in normal saline. A small-caliber US probe was inserted into one of the small bronchi to obtain the US images. The point where an image was recorded was marked with a pin, and that part was excised for microscopic examination. The US images appeared different among the three lung tissue patterns. The bars in a-c represent 1 mm. (Hematoxylin-eosin stain; original magnification, x2.5.)
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Figure 3b. US images and their corresponding photomicrographs of autopsied lungs. The autopsied lungs were from patients with (a) normal, (b) emphysematous, and (c) honeycomb lung. The lungs were fixed in formalin before being cut into 1-cm-thick samples. The samples were removed from formalin and soaked in normal saline. A small-caliber US probe was inserted into one of the small bronchi to obtain the US images. The point where an image was recorded was marked with a pin, and that part was excised for microscopic examination. The US images appeared different among the three lung tissue patterns. The bars in a-c represent 1 mm. (Hematoxylin-eosin stain; original magnification, x2.5.)
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Figure 3c. US images and their corresponding photomicrographs of autopsied lungs. The autopsied lungs were from patients with (a) normal, (b) emphysematous, and (c) honeycomb lung. The lungs were fixed in formalin before being cut into 1-cm-thick samples. The samples were removed from formalin and soaked in normal saline. A small-caliber US probe was inserted into one of the small bronchi to obtain the US images. The point where an image was recorded was marked with a pin, and that part was excised for microscopic examination. The US images appeared different among the three lung tissue patterns. The bars in a-c represent 1 mm. (Hematoxylin-eosin stain; original magnification, x2.5.)
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Patients
Endobronchial US evaluation of the 22 patients revealed a range of US appearances of different conditions. The findings at endobronchial US appear to be divisible into six echoic patterns (Table 2, patterns A–F), which are shown in Figure 4 together with corresponding CT scans in typical cases. Pattern A was most often encountered in lungs in which no lesion was identified on CT images. Pattern B was identified in only some but not all of the patients with interstitial pneumonia of either origin. Pattern C was identified in two patients with idiopathic pulmonary fibrosis, one patient with organizing pneumonia, two patients with lymphangitic carcinomatosis, and one patient with pulmonary dissemination of cancer. Pattern D was identified only in one patient with honeycomb lung. Pattern E was identified in two patients with pulmonary alveolar proteinosis and one patient with bronchiolitis obliterans organizing pneumonia (BOOP). Pattern F was also identified in one patient with BOOP and in two patients with lymphangitic carcinomatosis, in whom the findings were observed at the relatively proximal parts of the bronchus.
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Figure 4a. Six tentative echoic patterns (Table 1, patterns A-F) depicted on endobronchial US scans (left) obtained in the 22 patients with various interstitial and alveolar pulmonary diseases and their corresponding transverse CT images (right). The US images represent transverse planes to the inserted bronchi. Among the six patterns, (a) pattern A (patient 5), characterized by a uniformly diffuse fine granular pattern, was considered the normal echoic pattern because it was most frequently observed in normal appearing areas at CT; (b) pattern B (patient 14) is similar to pattern A except that this pattern contained a diffuse dense hyperechoic region at the inner field (arrows); (c) pattern C (patient 8) is characterized by nodular hyperechoic regions (*) scattered in a field with a fine granular pattern and a relatively hypoechoic field (arrows) when compared with patterns A and B at its center; (d) pattern D (patient 10) is a gross patchy combination of hyperechoic (arrows) and hypoechoic (*) pattern; (e) pattern E (patient 20) consisted mainly of a patchy hyperechoic (arrows) pattern; and (f) pattern F (patient 17) features a hypoechoic central ring (arrows), a hyperechoic middle ring (*), and a fine granular pattern (arrowheads) at the outermost ring. The bars on the US images represent 1 mm.
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Figure 4b. Six tentative echoic patterns (Table 1, patterns A-F) depicted on endobronchial US scans (left) obtained in the 22 patients with various interstitial and alveolar pulmonary diseases and their corresponding transverse CT images (right). The US images represent transverse planes to the inserted bronchi. Among the six patterns, (a) pattern A (patient 5), characterized by a uniformly diffuse fine granular pattern, was considered the normal echoic pattern because it was most frequently observed in normal appearing areas at CT; (b) pattern B (patient 14) is similar to pattern A except that this pattern contained a diffuse dense hyperechoic region at the inner field (arrows); (c) pattern C (patient 8) is characterized by nodular hyperechoic regions (*) scattered in a field with a fine granular pattern and a relatively hypoechoic field (arrows) when compared with patterns A and B at its center; (d) pattern D (patient 10) is a gross patchy combination of hyperechoic (arrows) and hypoechoic (*) pattern; (e) pattern E (patient 20) consisted mainly of a patchy hyperechoic (arrows) pattern; and (f) pattern F (patient 17) features a hypoechoic central ring (arrows), a hyperechoic middle ring (*), and a fine granular pattern (arrowheads) at the outermost ring. The bars on the US images represent 1 mm.
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Figure 4c. Six tentative echoic patterns (Table 1, patterns A-F) depicted on endobronchial US scans (left) obtained in the 22 patients with various interstitial and alveolar pulmonary diseases and their corresponding transverse CT images (right). The US images represent transverse planes to the inserted bronchi. Among the six patterns, (a) pattern A (patient 5), characterized by a uniformly diffuse fine granular pattern, was considered the normal echoic pattern because it was most frequently observed in normal appearing areas at CT; (b) pattern B (patient 14) is similar to pattern A except that this pattern contained a diffuse dense hyperechoic region at the inner field (arrows); (c) pattern C (patient 8) is characterized by nodular hyperechoic regions (*) scattered in a field with a fine granular pattern and a relatively hypoechoic field (arrows) when compared with patterns A and B at its center; (d) pattern D (patient 10) is a gross patchy combination of hyperechoic (arrows) and hypoechoic (*) pattern; (e) pattern E (patient 20) consisted mainly of a patchy hyperechoic (arrows) pattern; and (f) pattern F (patient 17) features a hypoechoic central ring (arrows), a hyperechoic middle ring (*), and a fine granular pattern (arrowheads) at the outermost ring. The bars on the US images represent 1 mm.
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Figure 4d. Six tentative echoic patterns (Table 1, patterns A-F) depicted on endobronchial US scans (left) obtained in the 22 patients with various interstitial and alveolar pulmonary diseases and their corresponding transverse CT images (right). The US images represent transverse planes to the inserted bronchi. Among the six patterns, (a) pattern A (patient 5), characterized by a uniformly diffuse fine granular pattern, was considered the normal echoic pattern because it was most frequently observed in normal appearing areas at CT; (b) pattern B (patient 14) is similar to pattern A except that this pattern contained a diffuse dense hyperechoic region at the inner field (arrows); (c) pattern C (patient 8) is characterized by nodular hyperechoic regions (*) scattered in a field with a fine granular pattern and a relatively hypoechoic field (arrows) when compared with patterns A and B at its center; (d) pattern D (patient 10) is a gross patchy combination of hyperechoic (arrows) and hypoechoic (*) pattern; (e) pattern E (patient 20) consisted mainly of a patchy hyperechoic (arrows) pattern; and (f) pattern F (patient 17) features a hypoechoic central ring (arrows), a hyperechoic middle ring (*), and a fine granular pattern (arrowheads) at the outermost ring. The bars on the US images represent 1 mm.
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Figure 4e. Six tentative echoic patterns (Table 1, patterns A-F) depicted on endobronchial US scans (left) obtained in the 22 patients with various interstitial and alveolar pulmonary diseases and their corresponding transverse CT images (right). The US images represent transverse planes to the inserted bronchi. Among the six patterns, (a) pattern A (patient 5), characterized by a uniformly diffuse fine granular pattern, was considered the normal echoic pattern because it was most frequently observed in normal appearing areas at CT; (b) pattern B (patient 14) is similar to pattern A except that this pattern contained a diffuse dense hyperechoic region at the inner field (arrows); (c) pattern C (patient 8) is characterized by nodular hyperechoic regions (*) scattered in a field with a fine granular pattern and a relatively hypoechoic field (arrows) when compared with patterns A and B at its center; (d) pattern D (patient 10) is a gross patchy combination of hyperechoic (arrows) and hypoechoic (*) pattern; (e) pattern E (patient 20) consisted mainly of a patchy hyperechoic (arrows) pattern; and (f) pattern F (patient 17) features a hypoechoic central ring (arrows), a hyperechoic middle ring (*), and a fine granular pattern (arrowheads) at the outermost ring. The bars on the US images represent 1 mm.
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Figure 4f. Six tentative echoic patterns (Table 1, patterns A-F) depicted on endobronchial US scans (left) obtained in the 22 patients with various interstitial and alveolar pulmonary diseases and their corresponding transverse CT images (right). The US images represent transverse planes to the inserted bronchi. Among the six patterns, (a) pattern A (patient 5), characterized by a uniformly diffuse fine granular pattern, was considered the normal echoic pattern because it was most frequently observed in normal appearing areas at CT; (b) pattern B (patient 14) is similar to pattern A except that this pattern contained a diffuse dense hyperechoic region at the inner field (arrows); (c) pattern C (patient 8) is characterized by nodular hyperechoic regions (*) scattered in a field with a fine granular pattern and a relatively hypoechoic field (arrows) when compared with patterns A and B at its center; (d) pattern D (patient 10) is a gross patchy combination of hyperechoic (arrows) and hypoechoic (*) pattern; (e) pattern E (patient 20) consisted mainly of a patchy hyperechoic (arrows) pattern; and (f) pattern F (patient 17) features a hypoechoic central ring (arrows), a hyperechoic middle ring (*), and a fine granular pattern (arrowheads) at the outermost ring. The bars on the US images represent 1 mm.
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Discussion
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By expelling air from air-filled sponges, autopsied lungs, and in vivo pulmonary parenchyma of patients, we successfully obtained echoic US images for evaluation. Air was expelled by soaking sponges in water and autopsied lungs in normal saline. For patients, the same effect was achieved by instilling normal saline in the peripheral pulmonary area by using the BAL technique. In addition, we found several different sonographic appearances in a range of disorders.
We acknowledge that our interpretation of the relationship between the echoic patterns and corresponding pulmonary disorders is speculative at this time since our study is preliminary. Because we used a transducer with a frequency of 20 MHz, the minimum resolvable size is approximately 77 µm. It is likely that the actual resolvable size is larger, perhaps much larger, given the difficulties in producing a transducer to meet the physical requirements imposed on it for catheter use. On the other hand, a normal alveolus is usually smaller than 200 µm. These facts suggest that the echoic patterns of the plastic sponge and peripheral pulmonary regions consisting of normal-sized alveoli might represent speckle patterns rather than direct US reflections of their fine structure. In contrast, the pore size of the vegetable sponge and the sizes of air spaces and interstitial septa of the autopsied honeycomb lungs are obviously much larger, and their echoic images might indeed contain direct reflections of these anatomic structures. By continuing this line of speculation, the echoic images obtained in this study, both in vitro and in vivo, likely represented mixtures of speckles and direct reflections of the peripheral pulmonary structures, and the different echoic patterns might be attributed to degrees of disease-related structural alterations of these peripheral areas. Clearly, further investigations are needed to compare the echoic patterns and pathologic findings in large patient populations.
Although we tentatively demonstrated as many as six patterns, some of them possibly represented slight variations in the other patterns (eg, pattern B might not be separable from pattern A because of their close resemblance). In addition, some of the patterns may simply be combinations of other patterns: Pattern C might be a mixture of patterns E and F. It is also entirely conceivable that further studies may reveal additional echo patterns. In addition, variability in the BAL technique may influence endobronchial US findings.
The extra requirements for endobronchial US after simple BAL consisted of only a 50-mL-larger saline injection followed by insertion of the US probe to the same bronchus.
By considering the clinical application of endobronchial US in the evaluation of pulmonary interstitial or alveolar diseases, the technique has shortcomings and possibilities. First, only a narrow area of the lung is imaged at a time. Therefore, it might be difficult to evaluate a more widespread condition. Second, because endobronchial US has to be inevitably accompanied by BAL, it may not be suitable for frequent repetition. Third, although findings at endobronchial US do not seem to have high disease specificity, and it cannot be used by itself for prospective diagnosis, it may deliver some potential benefits when combined with other established and currently used imaging techniques, such as conventional CT and thin-section CT (20,21). Fourth, endobronchial US may be useful in monitoring the locations for BAL or transbronchial lung biopsy. Bronchoscopists would be able to confirm that BAL was actually being performed at a lesion of interest by acquiring additional endobronchial US scans in the same bronchus. The additional imaging can then be followed by transbronchial lung biopsy in the same bronchus. More studies that focus on a comparison of endobronchial US images with pathologic and BAL findings, together with CT findings, seem warranted.
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ACKNOWLEDGMENTS
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We thank Dr Osamu Okada in our department for supplying the equipment for this study. Invaluable support from other physicians (Drs Nobuyuki Chatani, Akira Suda, Hiroshi Miyazawa, Takaaki Sugimoto, Reiko Watanabe, Tetsuro Moriya, and Masato Shingyoji), who were in charge of the patients, and secretarial help by Chieko Handa-Miyagi are also appreciated.
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FOOTNOTES
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2 Current address: Department of Internal Medicine II, Nara Medical University, Nara, Japan. 
Abbreviations: BAL = bronchoalveolar lavage,
BOOP = bronchiolitis obliterans organizing pneumonia
Author contributions: Guarantor of integrity of entire study, Y.T.; study concepts, Y.T., T.K.; study design, S.O., Y.T.; literature research, S.O., Y.T.; clinical studies, S.O., Y.T., H.K.; experimental studies, S.O., Y.T., K.H., H.K.; data acquisition, S.O., Y.T., K.H.; data analysis/interpretation, all authors; manuscript preparation, S.O., Y.T.; manuscript definition of intellectual content and editing, Y.T.; manuscript revision/review, Y.T., K.H., N.T., K.T., H.K., K.N., T.K.; manuscript final version approval, all authors.
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C.-H. Kuo, S.-M. Lin, H.-C. Chen, C.-L. Chou, C.-T. Yu, and H.-P. Kuo
Diagnosis of Peripheral Lung Cancer With Three Echoic Features Via Endobronchial Ultrasound
Chest,
September 1, 2007;
132(3):
922 - 929.
[Abstract]
[Full Text]
[PDF]
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T.-Y. Chao, C.-H. Lie, Y.-H. Chung, J.-L. Wang, Y.-H. Wang, and M.-C. Lin
Differentiating peripheral pulmonary lesions based on images of endobronchial ultrasonography.
Chest,
October 1, 2006;
130(4):
1191 - 1197.
[Abstract]
[Full Text]
[PDF]
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E. Kikuchi, K. Yamazaki, N. Sukoh, J. Kikuchi, H. Asahina, M. Imura, Y. Onodera, N. Kurimoto, I. Kinoshita, and M. Nishimura
Endobronchial ultrasonography with guide-sheath for peripheral pulmonary lesions
Eur. Respir. J.,
October 1, 2004;
24(4):
533 - 537.
[Abstract]
[Full Text]
[PDF]
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T.J. Shaw, S.L. Wakely, C.R. Peebles, R.L. Mehta, J.M. Turner, S.J. Wilson, and P.H. Howarth
Endobronchial ultrasound to assess airway wall thickening: validation in vitro and in vivo
Eur. Respir. J.,
June 1, 2004;
23(6):
813 - 817.
[Abstract]
[Full Text]
[PDF]
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J.-B. Liu and B. B. Goldberg
Catheter-Based Intraluminal Sonography
J. Ultrasound Med.,
February 1, 2004;
23(2):
145 - 160.
[Full Text]
[PDF]
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TOP
ABSTRACT
INTRODUCTION
