Introduction
Image-guided transthoracic needle biopsy (TNB), which is typically performed using computed tomographic (CT) guidance under local anesthesia and conscious sedation, is a minimally invasive procedure that can provide a definitive cytologic, histologic, or microbiologic diagnosis in 90% of patients with localized thoracic lesions. The decision to perform TNB in lieu of alternative invasive diagnostic procedures or imaging follow-up, particularly for indeterminate lung lesions, is usually made following a multidisciplinary review of relevant clinical, laboratory, imaging, and pathologic material and requires consideration of local expertise, the availability of alternative invasive diagnostic procedures, including bronchoscopy and video-assisted thoracic surgery (VATS), and the needs of the referring physician and patient.
Interventional radiologists also play an important role in the management of intrathoracic air and fluid collections, using cross-sectional imaging to guide catheter placement and monitor response to drainage, and in control of massive hemoptysis by embolization of bronchial or systemic arteries. More recently, CT-guided thermal ablation of early-stage lung cancer and limited pulmonary metastatic disease has shown efficacy as a minimally invasive alternative to surgical management and external beam radiation therapy in select patients with stage IA lung cancer or those with limited pulmonary metastases.
Transthoracic Needle Biopsy
Indications and Contraindications
The most common indication for TNB is the diagnosis of a solitary pulmonary nodule ( Fig. 19-1 ). Additional indications include diagnosis of a mediastinal mass, enlarged hilar or mediastinal lymph node, chest wall mass, or pleural mass or thickening. Most often the primary diagnostic concern is malignancy, but the diagnosis of opportunistic lung infection producing focal lung lesions in immunocompromised patients is an additional indication for image-guided TNB. In these latter patients, the retrieval of material for microbiologic stains and cultures rather than cytologic analysis for malignancy is the primary purpose for TNB. In selected patients with known non–small cell lung cancer (NSCLC) based on cytologic analysis from prior biopsy, core tissue TNB can be performed for immunohistochemical analysis (e.g., breast cancer metastases assessed for the presence of estrogen and progesterone receptors) or molecular testing (e.g., epidermal growth factor receptor or echinoderm microtubule-associated protein-like 4–anaplastic lymphoma kinase [ EML4-ALK ] rearrangement quantification) to help guide therapy. Occasionally a lesion thought likely to be benign based on clinical and imaging analysis is sampled using TNB to provide a definitive benign diagnosis.
The only absolute contraindication to TNB is the inability of a patient to cooperate for safe and successful sampling of the thoracic lesion in question. Most adults, even those with compromised pulmonary function, can undergo successful image-guided TNB using local anesthesia and either conscious sedation or monitored anesthesia care. For sampling of small lesions (<15 mm in diameter), the patient must be able to hold his or her breath when instructed to allow the operator to position the needle accurately within the lesion for successful retrieval of cytologic material. For larger lesions, particularly those at the lung periphery and those in the upper lobes that are less subject to craniocaudal motion during normal breathing, breath-holding is less important and TNB can be safely performed in most such patients without the need for the patient to respond to verbal commands. TNB can be performed selectively in patients receiving general anesthesia and endotracheal intubation when necessary. Even patients with severe dyspnea—who are unable to lie recumbent for CT-guided or fluoroscopically guided biopsy and cannot hold their breath—can undergo successful ultrasonographically guided TNB in the sitting position if the lesion to be sampled in the lung or pleura provides an adequate intercostal acoustic window to allow real-time visualization and biopsy. As with superior mediastinal lesions, an ultrasonographically guided suprasternal approach with the patient in the sitting position can be used.
Bleeding diatheses are only a relative contraindication to TNB and if identified can usually be corrected before the procedure. Although no objective data exist showing an increased risk for bleeding from TNB in patients with abnormal clotting parameters, such as elevated international normalized ratio higher than 1.5 or a platelet count lower than 50,000 cells/µL, most operators and published guidelines recommend preprocedure correction of abnormal bleeding parameters. Patients receiving antiplatelet agents, including aspirin and/or clopidogrel (Plavix) for prophylaxis after myocardial infarction, stroke, or recent coronary artery stent placement, who require TNB should have an assessment of the relative risks and benefits of discontinuing these agents compared with the potential bleeding complications induced by TNB. Published guidelines recommend discontinuing antiplatelet agents at least 5 days before TNB. Those patients who are considered to be at risk for thrombosis if anticoagulation or antiplatelet agents are withdrawn before biopsy can be bridged to receive intravenous heparin, which can be discontinued several hours before TNB, thereby providing a brief periprocedural window without anticoagulation. For large mediastinal masses or large peripheral lung or pleural/chest wall lesions, aspiration biopsy can be safely performed while the patient remains on anticoagulation or antiplatelet agents. If core tissue biopsy is required, typically for the diagnosis of an anterior mediastinal mass such as lymphoma or thymic neoplasm or for molecular analysis of NSCLC (adenocarcinomas), antiplatelet agents should ideally be discontinued for 7 days before biopsy. Patients who have had a prior pneumonectomy are at greater risk for respiratory compromise should they develop bleeding or pneumothorax from lung biopsy. However, because these complications can usually be anticipated and managed successfully, prior pneumonectomy does not preclude TNB for evaluation of a suspicious lesion in the residual lung.
Patient-Lesion Selection and Preprocedure Clinical and Imaging Evaluation
The decision to perform a TNB for diagnosis follows a thorough imaging evaluation and clinical assessment of the patient; typically this includes a consultation with a pulmonologist or oncologist who interviews and examines the patient to determine the clinical likelihood of malignancy after a suspicious thoracic lesion has been identified. For patients younger than 35 years without significant risk factors for malignancy who have focal lung lesions, imaging follow-up is almost invariably employed because the likelihood of malignancy in such patients is very low. Conversely, for patients with localized lesions who have a high prebiopsy likelihood of lung cancer, direct referral for surgical consultation is reasonable and more cost-effective, because the result of TNB will be unlikely to obviate resection of the lesion. Nevertheless, biopsy of likely malignant nodules can be of utility in patients who are poor surgical candidates, in whom the lesion is not amenable to VATS resection for intraoperative frozen section diagnosis, and in those with a history of prior malignancy in whom metastatic disease is a consideration and a TNB diagnosis of metastatic disease would not lead to surgical metastasectomy. For anterior mediastinal masses, core biopsy is almost always necessary for the initial diagnosis of lymphoma, particularly if diagnosis would preclude unnecessary sternotomy and resection, because these lesions are treated with radiation therapy and/or systemic chemotherapy.
It is important to determine the following before the procedure: (1) if TNB will alter the therapeutic approach to the lesion in question and (2) if a patient with suspected malignancy would opt for treatment based upon the results of the procedure should it yield malignant material. It is reasonable to refer patients with a high likelihood of NSCLC directly to VATS with sublobar or wedge resection for initial diagnosis because this procedure may provide both diagnostic material and definitive treatment, particularly for smaller, peripheral lung lesions likely to reflect adenocarcinoma as determined by thin-section CT analysis. In patients with stage I NSCLC who are older than 75 years, segmentectomy or extended wedge resection may be offered as an effective and potentially beneficial alternative to lobectomy, particularly if the patients have indolent (i.e., ground-glass or subsolid) lesions or significant medical comorbidities such as severe chronic obstructive pulmonary disease.
All patients referred for image-guided TNB should have a recent (optimally within 4 weeks of the procedure) thin-section (<2 mm slice thickness) CT examination of the lesion to be sampled. For TNB of mediastinal masses, enlarged mediastinal nodes, or pleural and chest wall masses, a recent contrast-enhanced CT or magnetic resonance imaging study helps determine the vascularity of the lesion and its proximity to critical vascular structures.
Informed consent is obtained on arrival to the radiology department for all patients undergoing TNB by either the individual performing the procedure or a health care professional who is able to describe the procedure accurately and answer questions for the patient and accompanying family members. The informed consent should include a detailed explanation of the TNB procedure itself, the expected length of time in the department (typically 1 hour for the procedure and 3 hours of postprocedure observation), and the benefits of the image-guided transthoracic approach compared with alternative noninvasive diagnostic options, including the option of not undergoing any further diagnostic procedures, once the risks and benefits of TNB have been described. The published incidence of TNB-induced pneumothorax (approximately 20%), chest tube insertion (3%), and hemoptysis (5%) are provided before the patient signs the printed consent form.
Choice of Imaging Guidance
Although TNB can be performed under fluoroscopic, CT, or ultrasonographic guidance, most operators use CT guidance exclusively or for the majority of their procedures. CT provides rapid and precise information regarding lesion and needle location. It is the only imaging modality that allows access to small, central lesions and safe access to enlarged mediastinal nodes ( Fig. 19-2 ). The ability to visualize intervening structures allows the operator to avoid bullae or large vessels in the projected needle path. Precise needle tip localization allows for a more confident assessment of adequacy of needle placement, particularly within small lesions or those with a necrotic or cavitary center. Complications such as bleeding or pneumothorax are readily identified and expeditiously managed.
Fluoroscopy can be used for biopsy of lesions that are easily seen radiographically. Ideally a biplane or C-arm unit that allows orthogonal views to be obtained during needle placement without rolling the patient from the recumbent position helps assess the accuracy of needle placement into the lesion. Radiation dose to the patient from fluoroscopically guided TNB is generally lower than from CT-guided TNB. Because most radiologists currently performing TNB have been trained to use CT for abdominal and pelvic image guided interventions, most radiologists use CT to perform TNB.
Ultrasonography can be used to guide TNB in select cases. Its primary advantage is real-time visualization during administration of local anesthesia, needle placement into the lesion, and lesion sampling, particularly automated core needle biopsy for histologic analysis. Intervening vascular structures are easily identified using Doppler so that they may be avoided. Although the technique is operator dependent, most radiologists have experience with diagnostic ultrasound probes and biopsy techniques that are easily applied to TNB. The use of ultrasonography to guide TNB is limited to lesions with an adequate acoustic window, such as anterior mediastinal masses and peripheral lung lesions with a broad pleural contact between the lesion and the chest wall ( Fig. 19-3 ).
Procedure
For CT-guided TNB the patient is placed recumbent and positioned to provide the shortest distance from the anticipated skin puncture site to the lesion, typically with the skin puncture site nondependent, allowing a vertical needle trajectory (see Fig. 19-1 ). For those patients unable to lie prone for the procedure because of breathing difficulties, the patient can be placed in the lateral decubitus position and a posterior puncture performed with the needle horizontally oriented. Most patients receive conscious sedation with relatively short-acting and readily reversible analgesic and amnestic agents, such as fentanyl and midazolam (Versed), respectively; if necessary, though, occasional patients require monitored anesthesia care or general anesthesia. For TNB performed using conscious sedation, a dedicated interventional radiology nurse administers the medications and monitors the patient’s oxygen saturation, heart rate, respiratory rate, and level of responsiveness throughout the procedure. Ideally the patient should be able to cooperate with consistent breath-holding, which is necessary to position the biopsy needle accurately into small lesions for successful sampling; this is particularly important for lesions near the diaphragm, which show significant craniocaudal movement during even tidal breathing.
Once the patient has been properly positioned, a scout view (a planar image of the thorax analogous to a frontal radiograph that is used to plan for the axial scans) is obtained at functional residual capacity. All scans obtained through the region of interest are likewise obtained at normal end-expiration, which is a comfortable and reproducible lung volume for the patient to achieve, even when sedated. For TNB of small lung nodules, a reconstructed scan thickness of no greater than half of the diameter of the lesion should be obtained for identifying and marking the needle puncture site. This provides a detailed view of the ribs and intercostal space, helps visualize the anticipated needle path and any intervening large vessels or bullae to be avoided, and minimizes partial volume averaging when assessing the position of the needle tip relative to the lesion being sampled. Thin sections are particularly important when sampling lesions with subsolid attenuation, because it is important to identify any solid components within the lesion to target for TNB to provide a more confident cytologic diagnosis of malignancy. Once the thin sections encompassing the lesion have been obtained, an electronic grid is superimposed on the image at the desired level for needle entry at the technologist’s console. This grid has major axes that mark the central meridian of the gantry in the coronal (x-axis) and sagittal (y-axis) planes and accurately correspond to laser lights on the CT gantry that project onto the patient’s skin at the chosen axial level. Measurements are then made on the console from the axis closest to the desired entry point, and using a ruler on the patient’s skin, this point is marked on the skin with an indelible marker.
The area is then prepared and draped with a sterilizing solution such as povidone-iodine (Betadine) or, for those with iodine allergies, chlorhexidine gluconate (Hibiclens). Local 2% lidocaine is administered subcutaneously to the entry site and deeper, approaching the pleural surface, because the parietal pleura is heavily innervated and is best anesthetized before transpleural placement of the biopsy needle. We and most operators employ a coaxial needle approach, with an outer thin-walled guide needle 18- or 19-gauge in diameter placed through the chest wall and neighboring pleura and positioned with its tip at the edge of the lesion. Samples are obtained by placing a thin 20- to 22-gauge aspiration or core needle through the outer coaxial guide needle. Patient breath-holding during needle placement and repositioning at the same end-expiratory volume as directed for the preliminary scans is key to accurate needle placement. Rapid assessment of needle position following advancement and repositioning can be obtained by repeated axial images through the region or by using CT fluoroscopy, which allows the operator to obtain several quick contiguous low-dose thin-section images through the lesion and needle without having to leave the room.
Once the guide needle is properly positioned at the edge of the lesion to be sampled, aspiration biopsy is performed by using a rapid, rotatory, and to-and-fro motion with the inner needle attached to a syringe with suction applied. The needle-syringe combination is removed and handed to a cytotechnologist who expresses the contents onto a glass slide and then fixes the slide in alcohol. The slides are then stained using toluidine blue O and examined with a microscope kept in an adjoining area. Additional aspiration samples are typically obtained for immunocytochemical analysis, cell block, or stains and cultures when necessary. Core tissue biopsy specimens can be obtained using 20-gauge or larger automated cutting needles and are reserved for situations when histologic analysis is deemed necessary ( Table 19-1 ).
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It is our practice to have a cytopathologist attend each image-guided biopsy procedure performed in the radiology department to provide a rapid interpretation of aspirated material using light microscopy. This feedback helps guide the radiologist to obtain additional aspirated specimens for culture or immunocytochemical analysis or to perform core needle biopsy for histologic analysis. Ideally the pathologist responsible for processing and interpreting the specimens obtained from the biopsy procedure is consulted before the biopsy; this allows for review of existing pathologic specimens that help in the interpretation of the biopsy specimen. If a core biopsy for histologic material is anticipated, as for a mediastinal mass, or if cultures are likely to be obtained, the pathologist or cytotechnologist can bring the appropriate materials to the site of the biopsy in the radiology department to process the specimens. CytoLyt solution should be used to preserve cellular material for cell block, and Roswell Park Memorial Institute medium is used for flow cytometry when lymphoma is a diagnostic consideration and core needle biopsy is not possible. Culture medium should be used for processing aspirates for microbiologic stains and cultures, even when infection is remotely suspected.
The initial approach to the pathologic evaluation of a TNB specimen obtained from a lung nodule or mass is to determine whether the lesion represents a small cell lung cancer (SCLC) or an NSCLC. This distinction is typically made on the basis of light microscopic examination of the stained specimen. In the majority of biopsy specimens showing an epithelial malignancy, additional immunocytochemical tests performed on aspirated specimens are needed for definitive determination of the primary site of disease. Immunocytochemistry involves the binding of monoclonal or polyclonal antibodies to specific antigens within tumor cells that render these antigenic proteins visible under light microscopy. The technique is versatile, because it can be performed on cytologic material obtained fixed on slides, on a cell block, or on histologic specimens that are embedded in paraffin. By using positive and negative controls and assessing for nuclear, cytoplasmic, or membranous staining, the pathologist can incorporate the results of the immunocytochemical stains into the diagnostic algorithm to render an impression regarding the specific cause of the sampled lesion.
Neuroendocrine markers, including chromogranin, synaptophysin, and CD56, are used to help confirm the diagnosis of small cell carcinoma, typical and atypical carcinoid tumors, and large cell neuroendocrine carcinoma. The markers most often used to determine the primary site of adenocarcinoma include thyroid transcription factor 1 (positive in lung and thyroid carcinoma) ( Fig. 19-4 ), cytokeratin 7 and 20 (positive in lung and colorectal carcinoma, respectively, and helpful in distinguishing the two), CDX2 (positive in colorectal carcinoma) ( Fig. 19-5 ), and estrogen receptors and HER2neu (positive in some breast carcinomas). Increasingly, core specimens for EGFR and ALK mutational analysis in patients with NSCLC thought to reflect adenocarcinoma should be obtained in patients who might benefit from such information ( Fig. 19-6 ).
Postprocedure Patient Management
Once the biopsy has been completed, the patient is monitored and precautions are instituted to minimize delayed complications. Typically, patients are kept recumbent, ideally with the biopsy side down) in an effort to reduce the likelihood of air leak from the lung puncture site and to decrease the likelihood that any alveolar hemorrhage induced by the biopsy will be aspirated into the uninvolved lung and produce respiratory compromise. After the biopsy has been completed, the coaxial needle is withdrawn and the patient is immediately moved by radiology personnel from the biopsy table to a stretcher with the biopsy side placed dependently; this avoids straining that would produce an increase in intrathoracic pressure that would promote air leak. Some radiologists inject autologous blood clot or saline upon withdrawal of the outer guide needle of a coaxial system in an attempt to seal the visceral pleural surface to prevent an air leak and pneumothorax following the biopsy. The patient receives supplemental oxygen as a precaution while recovering from conscious sedation and also to help promote resorption of any pneumothorax.
An upright chest radiograph is obtained 2 to 3 hours following the completion of the biopsy to assess for intraparenchymal or pleural hemorrhage and to exclude a pneumothorax. If no pneumothorax is detected, the patient can be safely discharged to home. If a small (<2 cm from chest apex to pleural line of upper lobe) pneumothorax is present and the patient is asymptomatic, the patient can be discharged safely if the pneumothorax was detected on CT during the biopsy. Otherwise, the patient is observed for an additional 2 hours to confirm that the pneumothorax is stable; if it enlarges, a pleural drainage catheter is placed under fluoroscopic or CT guidance, and the patient is admitted for observation and management. Any symptomatic, moderate-sized (2 to 4 cm), large (>4 cm), or enlarging pneumothorax is evacuated, and the patient is admitted for management. Select patients who undergo evacuation of a biopsy-induced pneumothorax with a catheter attached to a Heimlich valve can be safely managed on an outpatient basis, provided they have family or friends who can monitor them and if they live within short distance of a health care facility that can assess and manage them should their shortness of breath redevelop. Patients undergoing catheter drainage have underwater seal and suction until the pneumothorax has resolved and no air leak can be demonstrated, at which time the catheter can be safely removed.
Results
TNB has proven highly sensitive for the cytologic diagnosis of malignancy, with sensitivities exceeding 90% in the largest series published. The distinction between NSCLC and SCLC is made with high accuracy (>85%). A variety of factors have been shown to affect sensitivity, including the patient’s ability to lie still and cooperate sufficiently, the presence of underlying emphysema, operator experience, lesion size and location, lesion density, and availability of expert cytopathologic analysis; all these factors affect the TNB success rate. Even for lesions smaller than 10 mm, the sensitivity rate of TNB is high. Certain lesions, particularly large mediastinal lymphomas, such as nodular sclerosing Hodgkin lymphoma, and certain forms of non-Hodgkin lymphoma that contain significant fibrosis, localized fibrous tumors of pleura, and neurogenic lesions can be more difficult to diagnose cytologically; core needle biopsies are typically obtained for definitive diagnosis of these lesions. TNB samples of subsolid adenocarcinomas can be difficult to distinguish cytologically from atypia or adenomatous hyperplasia, although our experience suggests that the yield of TNB from these lesions is similar to that for solid nodules.
Precise cytologic diagnosis of benign pulmonary lesions, such as granulomas, is more difficult than that of malignant lesions because their relatively small size and typically hypocellular, fibrotic matrix makes retrieval of diagnostic material from TNB difficult. Core needle biopsy as an adjunct to cytologic analysis alone can increase the diagnostic yield from TNB of benign lesions to approximately 80%. Pulmonary hamartomas, particularly those with a significant cartilaginous component, can be difficult to aspirate, and core needle biopsy may be necessary for these lesions. Nevertheless, a skilled cytopathologist can make the diagnosis of a pulmonary hamartoma if provided adequate cytologic material ( Fig. 19-7 ).
The diagnostic yield of TNB for infection is somewhat lower than for malignancy. However, TNB can identify the causative microorganisms producing focal lesions in 80% of immunocompromised patients with suspected lung infection.
Complications
The most common complications of TNB include pneumothorax and bleeding. Pneumothorax develops in approximately 20% of patients undergoing TNB, of whom 3% require catheter or tube drainage. Factors that may be associated with an increased rate of TNB-induced pneumothorax include operator inexperience, advanced patient age, smaller lesion size, greater lesion depth from the pleural surface, the presence of underlying emphysema or obstructive lung disease, larger outer coaxial needle diameter, prolonged needle dwell time, and greater obliquity of the angle between the biopsy needle and the transgressed visceral pleural surface.
Hemorrhage ( eFig. 19-1 ) with or without hemoptysis develops in approximately 5% of patients undergoing TNB but is rarely the cause of prolonged observation, hospitalization, or need for transfusion. Biopsy-induced hemorrhage can preclude successful completion of TNB if it leads to intractable coughing or if blood at the biopsy site in the lung obscures the lesion being sampled, thereby rendering further attempts at accurate sampling impossible.
Rare complications of TNB include hemothorax from intercostal artery damage (see eFig. 19-1 ), air embolism ( eFig. 19-2 ), malignant seeding of the biopsy path, and, rarely, death.
Catheter Drainage of Intrathoracic Collections
Image-guided catheter or tube drainage of intrathoracic collections is an effective, minimally invasive method for treating a spectrum of intrapleural and intrapulmonary collections (see additional discussion in Chapter 79 ). This section will review the common indications, imaging considerations, catheter placement, and postprocedure management of intrathoracic collections with a review of complications and results in selected patients.
Parapneumonic Effusions—Empyema
Intrapleural collections amenable to image-guided drainage include a wide spectrum of common causes of pleural effusions (see additional discussion in Chapter 80 ). Selected patients with complicated parapneumonic effusions, defined as those unlikely to resolve spontaneously with treatment of the underlying pulmonary infection, or frank empyema can benefit from image-guided drainage, thereby avoiding prolonged hospitalization and open surgical drainage and/or decortication procedures ( Table 19-2 ).
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According to the American College of Chest Physicians consensus statement on the medical and surgical management of parapneumonic effusions, the anatomy of infected pleural fluid collections, the presence or absence of bacteria within the parapneumonic effusion, and pleural fluid chemistry have prognostic utility for predicting patient morbidity and mortality. Ultrasonography can detect very small parapneumonic effusions and helps guide safe, diagnostic sampling of these collections when necessary. Ultrasonographic findings that predict the likelihood of successful catheter or tube drainage, corresponding to early exudative stage parapneumonic collections, include small- to moderate-sized free-flowing, nonloculated collections lacking internal echoes or septations. Alternatively, ultrasonographically detected septations within complicated parapneumonic collections and empyemas make it more likely that a longer duration of chest tube drainage and longer hospital stay will be necessary.
Because these collections are likely to require fibrinolytics (see subsequent discussion) and ultimately surgical intervention, primary surgical treatment may be warranted in this subgroup of patients. Analysis of the entire extent of the pleural fluid collection and characterization of underlying lung and adjacent chest wall disease is best demonstrated on contrast-enhanced multidetector CT, which provides axial, sagittal, and coronal reformatted images that offer important information when considering therapeutic options for parapneumonic effusions. Similarly, early-stage exudative or fibrinopurulent effusions characterized on CT as dependent meniscoid or unilocular collections are best suited to small-bore image-guided catheter placement, with case series reporting success rates as high as 93%. The presence of enhancing visceral and parietal pleural layers encompassing a loculated pleural fluid collection is relatively specific for the presence of an empyema, although the identification of this split pleura sign does not preclude successful catheter drainage. Selected patients with unilocular empyemas or multiloculated collections who are poor surgical candidates for open management of infected pleural collections can be successfully managed with one or more image-guided catheters, either as definitive therapy or as a bridge to definitive surgical treatment.
After ultrasonographic localization for small-bore image-guided catheter treatment of parapneumonic effusions, we prefer a trocar catheter placement technique using a 14- or 16-French drainage catheter) for free-flowing or unilocular, nonseptated parapneumonic collections that have an adequate area of contact with the costal pleural surface and sufficient width to allow safe placement of the sharp-tipped trocar-catheter combination into the dependent part of the collection ( Fig. 19-8 ). For treatment of frank empyemas or large collections with ultrasonographically or CT-detected septations in nonsurgical patients, we prefer a large 28-French tube placed using a Seldinger technique, which involves placement of an 18-gauge needle followed by a guidewire and sequential dilation to 30-French diameter before tube insertion. If necessary, multiple catheters or tubes can be employed to drain different locules within the chest as depicted on CT, particularly for those patients felt to be poor candidates for primary surgical drainage.
