Lung Cancer Imaging by James G. Ravenel

Author:James G. Ravenel
Language: eng
Format: epub
Publisher: Springer New York, New York, NY

Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration

EBUS-TBNA is a promising modality for mediastinal staging. Initially, EBUS was performed by introducing a catheter with an ultrasound transducer at the tip of the catheter through the working channel of the bronchoscope (radial ultrasound probe). The lymph node was localized with the probe, and the catheter was then withdrawn. The lymph node would then be sampled with TBNA without visualization. More recently, a bronchoscope with a convex ultrasound probe has been developed allowing real-time ultrasound-guided TBNA (linear ultrasound scope, Fig. 8.2) [38]. EBUS-TBNA is performed under local anesthesia and conscious sedation in an outpatient setting. A 22-gauge TBNA needle equipped with an internal sheath is inserted through the working channel of the bronchoscope. The inner diameter of the needle allows the sample of histological cores in some cases. Doppler examination may be used immediately before the biopsy in order to avoid unintended puncture of vessels between the wall of the bronchi and the lesion. Under real-time ultrasonic guidance, the needle is placed in the lesion and suction is applied by a syringe. The needle is moved back and forth inside the lesion. Finally, the needle is retrieved and the internal sheath and the catheter are removed. The aspirated material is smeared onto glass slides, air-dried, and fixed in 95 % alcohol. Dried smears can be evaluated in real time by an on-site cytopathologist to confirm adequate cell material, and in a substantial number of cases, a preliminary diagnosis can be made. Histological specimens obtained are fixed in formalin before being sent to the pathology department. EBUS-TBNA can be used to sample the highest mediastinal (station 1), the upper paratracheal (station 2R, 2L), the lower paratracheal (station 4R, 4L), the subcarinal (station 7), as well as the hilar (station 10), the interlobar (station 11), and the lobar (station 12) lymph nodes (Fig. 8.1). A pooled analysis of 12 studies using EBUS for mediastinal staging showed a weighted sensitivity of 93 % (range 79–99 %), false-negative rate of 9 % (range 1–37 %), and specificity of 100 % [39]. The studies using EBUS involved patients with lymph node enlargement, which is consistent with a disease prevalence of approximately 70 %. In 2006, Herth et al. evaluated the performance of EBUS-TBNA in patients with lung cancer and a radiographically normal mediastinum [40]. That study showed an unexpected detection rate of 17 % in 119 lymph nodes 5–10 mm in size. In one out of six patients, a futile thoracotomy was averted using EBUS. This was followed by a study evaluating the accuracy of EBUS-TBNA for staging mediastinal lymph nodes in patients with lung cancer without enlarged lymph nodes on CT and no detectable PET activity in the mediastinum. There was a 9 % prevalence of mediastinal lymph node metastases. The sensitivity, specificity, and negative predictive value were 89 %, 100 %, and 99 %, respectively [41].

Fig. 8.2Convex probe endobronchial ultrasound. (a) The tip of the convex probe endobronchial ultrasound (Olympus XBF-UC260F-OL8, Olympus, Tokyo, Japan) has a linear curved array ultrasonic transducer of 7.

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