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N. Kurimoto



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    SC19 - Interventional Pulmonology in Diagnosis and Treatment of Thoracic Malignancies (ID 343)

    • Event: WCLC 2016
    • Type: Science Session
    • Track: Pulmonology
    • Presentations: 1
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      SC19.01 - Diagnosis of Lung Cancer: Multimodal Devices for Peripheral Pulmonary Lesions (ID 6677)

      16:00 - 16:20  |  Author(s): N. Kurimoto

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      Abstract:
      When bronchoscopy is performed for peripheral pulmonary lesions (PPLs), a radial ultrasonic probe can be inserted from the working channel of the bronchoscope to reach the PPL[1]. We began using this technique of endobronchial ultrasonography (EBUS) in 1994. EBUS using a guide sheath (GS) also began in 1996[2]. We would like to explain the technique and advantages of diagnosing PPLs using EBUS, GS, Navigation, and etc. 1) Radial ultrasonic miniature-probe A radial probe emits US while being rotated 360°; the reflected US waveform is rendered as an image. The radial probe scans from the bronchial lumen to provide a short-axis image of the bronchial and para-bronchial tissue. 2) Analyzing the internal structure of peripheral pulmonary lesions with a radial mini-probe EBUS imaging before surgery has been compared with histopathologic findings of surgically resected tissue to determine the internal structures of PPLs that can be depicted by EBUS[3]. PPLs can be classified as heterogeneous or homogeneous based on irregularities in brightness within lesions seen on EBUS. Internal structures within peripheral lesions that can be identified by EBUS include patent blood vessels, patent bronchi, hemorrhage, calcification, dilated bronchi, necrosis, and small amounts of air in alveoli. 3) EBUS using a guide sheath (EBUS-GS)[ 1, 2] The GS-covered probe is advanced to the PPL, then after confirmation by EBUS that the lesion has been reached, the probe is removed before inserting the brush and biopsy forceps through the GS that is held in place in the lesion. This technique enables cytology and biopsy to be performed several times with minimal risk of bleeding. 4) Insertion of the bronchoscope (saline immersion technique) After observing the bronchial lumen, the bronchoscope should be advanced while visualizing the branches to the bronchus near the peripheral lesion. Upon reaching a position where further advancement is not possible, flushing of 1-ml saline (total 5-10 ml) several times is performed through the working channel of the bronchoscope; this is done to fill the bronchus, remove any sputum, and visualize the lumen. The GS-covered probe is then inserted from the working channel into the bronchus. In cases of ground glass nodule (GGN), we do not perform the saline immersion technique. Because the saline immersion technique will occur EBUS images of hyperechoic points which resemble EBUS image of GGN. 5) EBUS visualization The operator advances the US probe from the working channel of the 4-mm bronchoscope towards the periphery and stops when some resistance is felt. The duration of X-ray fluoroscopy should be limited as much as possible; also, an iris of the fluoroscopy machine should be used for fluoroscopy. Scanning while pulling back the probe from the distal site to the proximal site reduces strain on the probe and provides clear EBUS images. We have reported that EBUS imaging of PPLs can be used to diagnose and assess the degree of differentiation between benign and malignant lesions[3]. PPLs are classified as type I if the internal echoes are homogeneous, type III if the internal echoes are heterogeneous, and type II if there are mainly hyperechoic lines and dots near the probe. About 92% of type I lesions were benign, whereas 99% of type II and type III lesions were malignant. The positional relationship between the probe and a PPL is classified as "within" (probe placement within a lesion), when the 360° area around the probe is entirely surrounded by the lesion; and "adjacent to" (probe is in contact with a lesion) when a lesion is depicted, but the 360° area around the probe is not entirely surrounded by the lesion. Higher diagnostic yields have also been reported for lesions with a positive bronchus sign on computed tomography. Minezawa et al.[4] reported that the CT bronchus sign was a significant predictive factor for successful bronchoscopic diagnosis in the multivariate analysis. We believe that bronchoscopists should trace the accurate bronchus leading to the PPL on CT axial images. When the lesion located in the middle lobe, the lingular segment, or bilateral lower lobes, we inverse CT axial images right to left, or left to right for watching the bronchus from the cranial site. When the lesion located in the right upper lobe, we rotate CT axial images counterclockwise 90 degrees. When the lesion located in the left superior segment, we rotate CT axial images clockwise 90 degrees. While tracing the bronchus on CT images, we could draw the illustration of the bronchus leading to PPLs. We usually use virtual bronchoscopic navigation (VBN) and compare the hand-written illustration of the bronchus leading to PPLs. Asano et al.[5 ]reported that the diagnostic yield by EBUS-GS and VBN was between 63.3 and 84.4% in reports on VBN for PPLs searched in PubMed as of November 2013. When the ultrasonic probe advanced to the different bronchus a little far from the target lesion, EBUS image is invisible. In this case, we should change the direction of the tip of the bronchoscope using the up and down lever of the bronchoscope under fluoroscopy. We select the direction of the tip of the bronchoscope for facing the target lesion, and pull back and push the probe/GS for trying to insert the target lesion. When the ultrasonic probe advanced to the bronchus adjacent to the target lesion, EBUS image is called as “adjacent to”. In this case, we could change the direction of the tip of the bronchoscope using the up and down lever of the bronchoscope under the EBUS image. We use the up or down lever of the bronchoscope for changing the position of the probe and GS (probe/GS) to be close to the target lesion on EBUS image. Then we keep the same angle of the tip of the bronchoscope, and pull back and push the probe/GS for trying to insert the target lesion. 6) Cytology and tissue biopsy from the guide sheath The GS tip is placed within or adjacent to the PPL before passing the brush and biopsy forceps through the GS. References Kurimoto N, Fielding D, Musani A. Endobronchial Ultrasonography. 2011, Willy Blackwell Kurimoto N, Miyazawa T, Okimasa S, Maeda A, Oiwa H, Miyazu Y, Murayama M. Endobronchial ultrasonography using a guide sheath increases the ability to diagnose peripheral pulmonary lesions endoscopically. CHEST 2004; 126: 959-65. Kurimoto N, Murayama M, Yoshioka S, Nishisaka T. Analysis of the internal structure of peripheral pulmonary lesions using endobronchial ultrasonography. CHEST 2002; 122: 1887-94 Minezawa T, Okamura T, Yatsuya H, et al. Bronchus sign on thin-section computed tomography is a powerful predictive factor for successful transbronchial biopsy using endobronchial ultrasound with a guide sheath for small peripheral lung lesions: a retrospective observational study. BMC Med Imaging. 2015 21; 15:21 Asano F, Eberhardt R, Herth F. Virtual Bronchoscopic Navigation for Peripheral Pulmonary Lesions. Respiration 2014; 88: 430-440

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