Transthoracic Needle Biopsy (TNB)

Transthoracic needle biopsy (TNB) is a safe rapid method used to achieve definitive diagnosis for most thoracic lesions, ^[1] whether the lesion is located in the pleura, the lung parenchyma, or the mediastinum. Diffuse disease and solitary lesions are equally approachable. Most TNBs are performed on an outpatient basis by using local anesthesia with or without conscious sedation. Virtually any location in the chest can be safely accessed by means of TNB. These percutaneous techniques are discussed in this article.

This article addresses biopsy of lesions that require transthoracic needle placement. Biopsy of the chest wall, ribs, and thoracic spine is included in Percutaneous Needle Technique Musculoskeletal Biopsy.

Klein et al reported computed tomography-guided TNB (CT-TNB) as a safe and accurate technique in the pathologic diagnosis of sarcoidosis, particularly when core tissue specimens are obtained. ^[2] The authors studied the records of 41 biopsies in 41 patients (1997-2007) of enlarged mediastinal lymph nodes for sarcoidosis. Core needle biopsy was shown to have a significantly higher yield than fine-needle aspiration cytology (96% vs 78%). ^[2]

Similarly, Kallenberg et al found that TNB is a safe diagnostic procedure in patients with hematologic malignancies and has the potential of making specific diagnoses with minimal morbidity. ^[3] In 53 patients with hematologic malignancies who underwent TNB during 1999-2007, the most common underlying hematologic malignancy was non-Hodgkin lymphoma (20 patients). Lesions were most frequently located in the left upper lobe (16); 33 lesions were pleural based; and 9 had cavitation. TNB established specific diagnoses in 22 patients (malignancies in 12; infections in 10). Sensitivity for malignancy was 50.0%, sensitivity for infection was 40.0%, and there were no false-positive results. Complications included self-limited small-volume hemoptysis in one patient and pneumothoraces in eight patients, one of whom required chest tube placement. The results of TNB led to changes in antimicrobial therapy for 8 of the 22 patients with specific diagnoses. ^[3]

In a more recent retrospective study (2012-2016) of 227 patients who underwent 223 CT-guided percutaneous TNB (PTNB) for pulmonary lesions, risk factors for hemoptysis during the procedure included lesions being subsolid and lesion depths more than 1 cm. ^[4] However, transversal through the central part of the lesion using PTNB was not a risk factor for procedure-related hemoptysis.

In a study of 105 patients, Tuna et al concluded that CT-guided biopsy is a safe and easy procedure that provides an accurate diagnosis of benign and malignant lung lesions without resulting in a meaningful increase in complications. ^[5]  Similar data were reported from a 2017 meta-analysis that evaluated complication rates of CT-guided transthoracic lung biopsies comprising data from 8,133 core biopsies procedures and 4,630 fine-needle aspiration (FNA) procedures. ^[6]  Minor complications were more common and more frequent in CT-guided core lung biopsies than FNA, but the rate of major complications was not only low but similar between the two procedures. Although no significant risk factors for complications were identified for core biopsies, those for FNA complications were smaller nodule diameter, larger needle diameter, and increased traversed lung parenchyma. ^[6]

Transthoracic needle biopsy (TNB) is performed most often to document metastatic, inoperable, or recurrent neoplastic disease or to obtain material for culture in patients in whom infection is suspected.

In contrast, many physicians believe that TNB is never indicated in patients with a resectable solitary pulmonary nodule (SPN). The argument against TNB is as follows: if an SPN is malignant, it must be removed. If TNB fails to reveal a malignancy, the SPN still must be removed under the presumption of a false-negative biopsy result. Because either result leads to surgery, subjecting the patient TNB is unnecessary.

This argument may have made sense in the early days of cytopathology, when a specific benign diagnosis was rarely achieved. However, such reasoning carries little weight today. For a patient who is a good surgical candidate and who is at high risk for lung cancer, surgery is the appropriate first step if the patient develops a new resectable mass with imaging characteristics typical of primary lung cancer. However, many, if not most, patients presenting with a SPN do not fit this description. Specimens obtained during percutaneous TNB do not help in diagnosing benign solitary pulmonary nodules.

When a bronchogenic neoplasm is suspected, biopsy of the lesion is often needed to determine the cell type before the course of treatment is planned. This is particularly true in small cell carcinomas, for which surgery is not the primary treatment. When surgery is contraindicated for other reasons, such as poor pulmonary function, extensive pulmonary emphysema, or previous pneumonectomy, chemotherapy and/or radiation therapy cannot be started until proof of malignancy is established by means of biopsy of the lesion. The same need to establish the cell type exists when a thoracic metastatic lesion occurs in a patient who has more than 1 primary neoplasm.

The coauthor uses a 21- or 19.5-gauge needle (EZ-EM, Inc., Westbury, NY), which often yields a core of tissue that allows for histopathologic analysis. The large needle improves the yield in the definitive diagnosis of a hamartoma, granuloma, carcinoid, lymphoma, or any lesion for which a fragment of tissue rather than just a few cells is necessary to establish a diagnosis. (Hamartoma a common benign tumor of the lung that appears as a solitary pulmonary nodule. Hamartoma is readily diagnosed by means of TNB.)

Malignant lesions are differentiated from benign lesions by using TNB in as many as 90% of all cases. ^[7] The exact cell type of the lesion is determined less frequently than this, with concordance of only 73.6% between specimen analysis of tissue retrieved with TNB and tissue retrieved with thoracotomy. ^[8]

TNB alters the course of therapy. ^{[9, 10]} Most common benign causes of SPN can be diagnosed with the help of TNB. ^[9] With the dissemination of low-dose CT to screen for lung cancer, additional patients are required to undergo biopsy of an indeterminate SPN. Most lesions may be due to benign causes, such as granulomatous, inflammatory, or fungal disease. When results of positron emission tomography (PET) or conservative follow-up studies are inconclusive or when clinicians wish to prevent unnecessary surgical intervention in this relatively low-risk population, biopsy can be offered as an alternative. In such cases, the diagnostic yield for benign disease should be maximized by using the appropriate technique and needle.

With the advent of PET-CT and combined PET, a new group of lesions are being examined with biopsy. PET images are used to target the exact location of biopsy to the site of metabolic activity, especially in suspected recurrences, treated neoplasms, or large lesions with necrosis. Lesions that are morphologically too small or initially thought to be benign but that have substantial metabolic activity may be successfully evaluated with biopsy by using preprocedural PET images as guides. In the patient with high risk of postbiopsy complications, a positive PET study may obviate tissue confirmation before treatment.

Contraindications include uncorrectable bleeding disorders and a patient's inability to cooperate during the procedure.

Although advanced chronic obstructive pulmonary disease (COPD) and deep lesions correspond to increased rates of pneumothorax, these are not contraindications.

Development of a pneumothorax necessitating chest-tube placement is uncommon.

As with fluoroscopy, the prone and supine positions are usually easy for a patient to assume and maintain. It is more difficult for patients to hold completely still if they are in an oblique position, but the use of bolsters can help stabilize their position.

The decubitus position occasionally helps the clinician stay in an extrapleural location because the dependent hemithorax is compressed. If a pulmonary abscess is suspected, the decubitus position can help prevent flooding the contralateral lung with infected material during the procedure.

Laboratory studies

Obtain the prothrombin time (PT) and an international normalized ratio (INR) in patients with known or suspected liver disease, in patients with known liver metastasis, or in patients receiving therapy with warfarin (Coumadin).

Obtain activated partial thromboplastin time (aPTT) in patients receiving heparin.

Obtain CBC counts in patients with a high risk of bleeding to determine their baseline hemoglobin concentration. Also obtain a CBC count in patients in whom thrombocytopenia is suspected.

Imaging studies

Obtain 2-view chest radiographs and CT scans even if the lesion will be sampled by using fluoroscopic guidance.

Chest CT scans help in determining the depth of the lesion, the 3-dimensional relationship of the lesion with adjacent structures, and the safest route of approach. In general, the route closest to the skin and through the fewest pleural fissures is preferred. The risk of pneumothorax increases as increasing numbers of fissures are transgressed.

For small lesions, a comparison of CT scans with the fluoroscopic views obtained during the procedure confirms that the faint shadow depicted on the monitor is the lesion to be aspirated.

CT scans also are valuable for detecting additional pulmonary nodules or hilar or mediastinal adenopathy.

Transthoracic needle biopsy procedure

Preprocedural details

Written informed consent is obtained, including consent for possible chest-tube placement. Most procedures are performed safely with local anesthesia alone. The patient should be informed and educated about the procedure, its benefits, and its risks. This information diminishes any apprehension or anxiety the patient may have and helps improve patient-physician cooperation and interaction during the procedure.

The patient should be able to follow breathing instructions, and he or she should be acutely aware of any breathing difficulty or pain. If conscious sedation must be used, patients are assessed for sedation per institutional guidelines. An intravenous (IV) line is placed to deliver sedatives and resuscitation medications as needed. Sedation should be tailored to the needs of each patient, and it should account for the possible deleterious effects of decreased respiratory drive. Most patients can tolerate TNB well when given midazolam (Versed) 1-2 mg IV and fentanyl 50-100 mcg IV throughout the examination.

Pulse oximetry, blood pressure, and heart rate are monitored, and a nurse who is given no other responsibilities administers the sedatives. Oxygen and tubing for oxygen delivery should be available, as are the reversal agents naloxone hydrochloride (Narcan) and flumazenil (Romazicon). A chest-tube insertion kit should be readily available in the biopsy suite. If CT is used during biopsy of a small nodule and if repeated breath holding is necessary, sedation may interfere with the examination. Once sedated, the patient may no longer be able to repetitively suspend his or her respiration in a similar fashion for imaging, needle placement, and confirmational imaging. This problem is not an issue the real-time methods of fluoroscopy, CT fluoroscopy, or ultrasonography are used.

Imaging guidance

Before the advent of CT scanning, fluoroscopy was the method of choice for guiding transthoracic biopsies. Units with C-arms or biplane capabilities offer the best choice for a quick, easy, and accurate procedure. CT (and the less commonly used sonography) has gradually replaced fluoroscopy, not necessarily because they are a better method but because they are widely available. As discussed later, the use of ultrasonography to guide biopsy has limitations. However, in developing countries where fluoroscopic and CT units are scarce, the use of ultrasound machines to guide biopsy may be the only alternative, especially if nodules or masses are in the chest wall or peripheral pleura.

Transthoracic needle biopsy (TNB) can be performed under fluoroscopic guidance in most lesions that can be demonstrated on chest radiographs. In the author's experience, the smaller the lesion, the more likely the biopsy will yield diagnostic material when fluoroscopy versus conventional static CT is used. If CT-fluoroscopy is available to the operator, the likelihood of obtaining diagnostic material is best. Considerations to address with the various TNB guidance methods are discussed below.

Fluoroscopic guidance versus CT guidance

Fluoroscopy is preferred in most patients with pulmonary parenchymal lesions if CT-fluoroscopy is unavailable. The smaller the lesion, the more likely it is that TNB performed under fluoroscopic guidance will successfully lead to diagnosis. Except in the CT-fluoroscopic technique, CT cannot compete with fluoroscopy in TNB of lung nodules.

Despite the low level of technology, fluoroscopy can be superior to CT in guiding TNB in several ways. Note the following:

• Fluoroscopy allows real-time tracking of the lesion as it moves with patient respiration.

• Because the lesion usually moves when the needle encounters it, real-time imaging helps ensure that the needle remains in the lesion or that it reenters the lesion as it is aspirated.

• A route that avoids the ribs and transverse processes can be selected easily.

• If the patient develops a pneumothorax and if the lesion must be aspirated additional times because the initial sample is inadequate, the approach can be adjusted rapidly to account for changes in the position of the lesions. With CT, rescanning the entire region is necessary to find the new position of the lesion, which may change rapidly.

CT is superior to fluoroscopy in guiding TNB in the following situations:

• For mediastinal lesions, as CT allows discrimination between the lesion and the adjacent mediastinal structures

• For small hilar lesions that cannot be differentiated from hilar structures under fluoroscopy

• For many lesions of the chest wall

• For small nodules that are not well visualized with fluoroscopy

Fluoroscopy approaches

Posterior approach: The author prefers the posterior approach for fluoroscopy because the posterior ribs are revealed and readily avoided and because the patient cannot see the needle entering the chest.

Anterior approach: Patients are usually most comfortable lying supine. The patient can easily get on and off the table from the supine position. The patient is also in position for rapid chest-tube placement if it is needed.

Lateral or oblique approach: Any position that is not perpendicular to the floor can cause problems. Experience and a good C-arm or biplane fluoroscopic unit helps greatly. This approach can be difficult to use if the fluoroscope cannot be positioned obliquely, as in a basic radiography-fluoroscopy room. Moving the patient into an oblique position with the needle in place is not a good option because the movement of the muscles of the chest wall and the upper extremities deflect the needle.

CT-guided TNB

Verification that the needle is in the lesion is most readily and convincingly documented with CT. However, the needle can become dislodged from the lesion between the time the confirmation image is acquired and the time the specimen is obtained. Dislodgement can occur because of patient respiratory motion or because of the operator's motion during aspiration. In the author's experience, dislodgement is not an issue with pleural-based masses, mediastinal lesions, large parenchymal masses, and it is most likely to occur when a small, firm parenchymal nodule is sampled. ^{[2, 11, 12, 13, 14]}

Thoracic-cage considerations

A rib or transverse process that appears to be in the way of needle advancement might be volume averaging on the section and not a true obstacle. Thin collimation can reveal what really lies ahead of the needle, but additional imaging is required because patient motion and respiratory variation are exaggerated. If the needle does encounter bone, the osseous structure can usually be avoided with slight manual displacement of the needle along with the superficial soft tissues of the needle track. Recall that the neurovascular structures are inferior to the posterior ribs; therefore, do not slip in under a posterior rib.

Ultrasonography-guided TNB

Biopsy of a chest-wall or a pleural-based lesion is often simply and rapidly performed under ultrasonography guidance, which avoids exposing the patient and operator to ionizing radiation. If the lesion is in the chest wall, it is often readily depicted on sonograms. Pleural-based lesions are depicted even more readily than chest-wall lesions because acoustic reflection of the lung flanks the mass.

For peripheral pulmonary lesions that are 80 mm or more from the chest wall, endobronchial ultrasonography with a guide sheath (EBUS-GS) may be a safer technique than CT-guided transthoracic needle aspiration (CT-TNA), albeit with a slightly lower diagnostic rate. ^[15] For lesions 80 mm or closer to chest wall, CT-TNA has a higher diagnostic rate than EBUS-GS but it is also associated with a greater risk of complications such as pneumothorax and intrapulmonary hemorrhage. ^[15]

CT-fluoroscopically–guided TNB

CT-fluoroscopic guidance is reported to be a reliable and effective method, and it is becoming a popular technique as scanners with this capability become widely available. CT-fluoroscopy has replaced fluoroscopic guidance as the method of choice for guidance at the author's institution.

For TNB of large pulmonary masses and for mediastinal or hilar lesions, CT-fluoroscopy can substantially reduce procedure time. Although small pulmonary nodules can be readily targeted with CT-fluoroscopy, it is still difficult to verify that the needle remains within the moving nodule as it is aspirated. The problem is due to the need to move the patient in and out of the imaging plane, which requires 1 hand, while simultaneously aspirating with and controlling the biopsy needle, which often requires 2 hands. In this situation, manual core biopsy (eg, with a Temno core gun; Bauer Medical International, Santo Domingo, Dominica Republic) can be definitive because the coring device can be demonstrated in position through the lesion before it is fired.

A potential disadvantage of CT-fluoroscopy is exposure of the patient and operator to high doses to radiation. To minimize operator exposure, an approach that incorporates caudal-to-cranial or cranial-to-caudal angulation is best. The ribs make selecting such an approach in the thorax is made difficult.

Machines capable of CT-fluoroscopy are often the best and fastest scanners in the department. It may be difficult to justify interrupting the throughput of patients for diagnostic scans to perform a procedure that is often just as easily performed by using a less expensive piece of equipment. As CT-fluoroscopy capable machines became ubiquitous, they replaced fluoroscopy as the method of choice.

Vendors have yet to create an operator-friendly way of moving the patient in and out of the field. A rocking foot pedal may be extremely useful. For now, the present authors disarticulate a sterile 20-mL syringe and use the outer section as a sterile cover over the tiny handle that is used to move the patient in and out of the beam. This technique occupies 1 hand, making it more difficult to perform biopsy than it would be if the table could be controlled with a foot.

Transthoracic needle biopsy techniques

Coaxial or single needles can be used; either type is acceptable. Radiologists performing TNB should be familiar with both techniques. To perform TNB in a patient with a lung nodule, the author uses a 22-gauge Chiba needle. The needle is typically 10-15 cm long, and the depth of placement is determined on CT scans, even if fluoroscopy is used for guidance.

In many patients, the coaxial technique is best. The coaxial technique involves placement of the guide needle into position near or within the mass. A second device is placed through the guide needle to obtain tissue. The device used to obtain tissue may be an aspirating or cutting needle or a core gun. A typical coaxial setup includes an 18-gauge Chiba needle as the guide needle and a 22-gauge Chiba needle for fine-needle aspiration (FNA) or a 20-gauge gun to obtain a core (see image below).

Advantages of the coaxial method are summarized as follows:

• Although detailed imaging is needed to place the guide needle, the rest of the biopsy can be performed with little or no additional imaging.

• Both aspirates and cores can be obtained through the same access.

• The guide needle can be used to obtain a final, large-volume aspirate at the end of the procedure or to place a blood patch as the needle is withdrawn.

Disadvantages of the coaxial technique include the creation of a large defect in the pleura and the risk that room air can be sucked into the chest through the outer needle when the inner needle is placed or removed.

Indications for using the coaxial method are as follows:

• If infection is considered more likely than neoplasm (Large volumes can be obtained.)

• If the patient is returning for a second FNA because analysis of the specimen obtained on the first attempt was nondiagnostic (Use the coaxial approach with the intent to obtain 20-gauge cores.)

• If placement of the needle is demanding and require extensive imaging time ^[16]

• If the lesion is believed to have a tissue type that requires a core specimen for diagnosis, such as sarcoma or hemangiopericytoma

• If the intention is to treat the lesion by using intratumoral injection after a biopsy sample is obtained, as with intratumoral gene therapy

• If the lesion is in the mediastinum, particularly if a trans-sternal approach is used

Regardless of the technique used to image or approach the lesion, the most critical member of successful TNB team is the cytopathologist. The radiologist and the cytopathologist form a team. Coordinate with the cytopathologist so that the specimen can be received and analyzed as soon as it is removed from the chest. An insufficient sample results in a repeated pass if possible. Additional tissue can complement a specimen that is almost diagnostic. The radiologist's impression may help the cytopathologist in narrowing the diagnosis.

Advanced techniques

Trans-sternal approach

If a mass in the mediastinum can be aspirated without transgressing the pleura, the risk of pneumothorax diminishes to zero. Anterior mediastinal masses can often be accessed when the approach is through the sternum and avoids the pleura.

Tips for using the trans-sternal approach include the following:

• Use an 18-gauge Chiba needle as a guide needle. The Chiba needle appears blunt, but it passes through the sternum with relatively little pressure applied while drilling.

• The guide needle jumps forward when the anterior cortex is breached. When the guide needle encounters the posterior cortex, check its position to ensure that the angle is correct (see image below). Correcting the angle after the posterior cortex is crossed is difficult. The parallelogram of the sternum locks the guide needle in position. (This is true of any transosseous approach.)

  Transthoracic needle biopsy (TNB). Computed tomography scan obtained during trans-sternal coaxial fine-needle aspiration (FNA) of prevascular adenopathy. The path of the needle should be checked before the posterior cortex is penetrated.

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• The periosteum on the far side of the posterior cortex is innervated. Be prepared to administer additional local anesthetic through the guide needle when it reaches the periosteum.

• Sensing the crossing of the posterior cortex is difficult because no give is felt as when the needle crosses the anterior cortex. Therefore, it is imperative to watch the depth of the guide needle to avoid going too deep. In addition, the patient feels pain when the innervated periosteum of the posterior sternal cortex is reached.

• After the guide needle is in the anterior mediastinum, use a curved 22-gauge Chiba needle to aspirate coaxially (see first image below). The patient may develop a pneumomediastinum but not a pneumothorax (see second image below).

  Transthoracic needle biopsy (TNB). Computed tomography scan obtained during trans-sternal coaxial fine-needle aspiration (FNA) of prevascular adenopathy. After the guide is in place, FNA and core samples can be rapidly obtained by means of a coaxial method. The image shows a slightly curved 22-gauge Chiba needle placed coaxially through the 18-gauge Chiba needle that was used to breech the sternum. By curving the 22-gauge tip, the FNA needle can be steered. Also, turning the hub during aspiration swings the tip through an arc; this maneuver allows the clinician to sample a volume of tissue greater than that obtained when the tip is straight.

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  Transthoracic needle biopsy (TNB). Computed tomography scan obtained during trans-sternal coaxial fine-needle aspiration (FNA) of prevascular adenopathy. Note that air can collect harmlessly in the anterior mediastinum during this approach, but it will not cause a pneumothorax.

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• Placing the needle through bone does not cause any more pain than placing it through soft tissue.

• Despite the lack of pain, use sedation because watching a needle being drilled through one's own sternum can be an unpleasant experience for patients.

• Although the procedure may appear to be painful, patients do not have any more pain with trans-sternal needle biopsy than with any other kind of biopsy procedure. Remember to use local anesthetic at both the superficial and deep periosteal layers of the sternum.

Transvenous approach

A right paratracheal node is usually posterior to the superior vena cava (SVC). A 22-gauge needle may be placed safely through the SVC to reach the node.

Tips for using the transvenous approach include the following:

• Use the coaxial technique. Place the tip of the 18-gauge guide needle just anterior to the SVC.

• Minimize the number of transvenous passes.

• Combine the trans-sternal with the transvenous approach if needed to keep the track within the mediastinum (see image below).

  Transthoracic needle biopsy (TNB). Computed tomography scan obtained during trans-sternal transcaval coaxial fine-needle aspiration (FNA) of a right paratracheal adenopathy. For this approach, an 18-gauge guide is placed through the sternum but not through the superior vena cava (SVC). A 22-gauge Chiba needle is posteriorly advanced through the SVC into the nodes. Expect a tiny, insignificant amount of bleeding into the mediastinum. As long as the patient has normal coagulation parameters, no bleeding problem should ensue. Remember that the first aortograms were performed in similar fashion by passing an 18-gauge needle directly into the ascending aorta.

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• Widen the mediastinum temporarily by injecting sterile isotonic sodium chloride solution. This method can increase the likelihood of keeping the needle track extrapleural. ^[17]

• Place the patient in the decubitus position to widen the extrapleural window (see image below). This positioning technique is especially useful for patients undergoing biopsy of an adrenal mass.

  Transthoracic needle biopsy (TNB). With the patient prone, the route is narrowed. The margin of safety can be improved by placing the patient in the left lateral decubitus position. Clinical tip: When a procedure is performed with the patient in the prone position, note that the patient's left side is on the right, as shown on this prone image. Be sure to check the position of the liver and spleen. Computed tomography technicians are often confused when a patient is positioned prone, and with a keystroke, they can flip the image back and forth. Ensure that the correct side is being addressed.

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Postoperative details

If the pleura is crossed

If the needle crossed or is suspected to have crossed the pleura, keep the patient recumbent after TNB. Slide the patient from the procedure table onto a gurney. Do not allow the patient to get up and ambulate or to sit in a wheelchair. As long as the patient is stable, do not rush to perform postprocedural chest radiography. Wait 30 minutes with the patient quietly relaxing on the bed. After 30 minutes, the postprocedural chest radiograph can be obtained. If no pneumothorax is present, the patient can begin to ambulate, eat a meal, and move around the hospital.

A chest radiograph is obtained after 3 hours to exclude a delayed pneumothorax. The patient is discharged home if the delayed image shows no pneumothorax.

If the patient develops a pneumothorax during TNB or if the first post-TNB chest radiograph demonstrates a pneumothorax, assess the patient's oxygen saturation and vital signs. If the vital signs are deteriorating or if the patient is complaining of heaviness in the chest or shortness of breath, treat the pneumothorax. If the patient is asymptomatic and if his or her vital signs are stable, have the patient rest quietly, breathing 2 L of oxygen given by nasal canula for 1 hour. Then, obtain a chest radiograph and look for signs of worsening or a stable, improving, or resolved pneumothorax. Patients with an unstable or symptomatic pneumothorax are treated with placement of a chest tube.

An asymptomatic, stable, or resolving pneumothorax is not drained. In patients with such a finding, obtain another chest radiograph 4 hours after biopsy. If the patient remains asymptomatic and if the pneumothorax is stable or resolving, discharge the patient. If otherwise, place a chest tube.

If the pleura is not crossed

If the needle does not cross the pleura, such as during mediastinal or pleural-based TNB, a follow-up chest radiograph is not needed. Discharge the patient after 30 minutes of observation.

A flowchart can be used to time chest radiography and to aid in patient disposition (see first image below). All chest radiographs must be obtained by using the same technique. The current author prefers the upright anteroposterior view with full expiration. The flowchart appears complex. In basic terms, if the patient develops an unstable or symptomatic pneumothorax, placement of a chest tube is warranted (see second image below).

In general, computed tomography (CT)-guided transthoracic needle biopsy (TNB) is a safe procedure that provides improved accuracy (97.6%) of preoperative tissue diagnosis for peripheral lung nodules than transthoracic needle aspiration (TNA) and in obtaining suitable tissue samples for molecular testing in suspected lung adenocarcinomas. ^[18]

Percutaneous CT-guided lung biopsy can be performed in patients with mild to moderated pulmonary hypertension without a significant in complications such as hemorrhage, moderate hemoptysis, pneumothorax, chest tube placement, and hemothorax. ^[19]

Pneumothorax

Complications are rare with TNB as long as pneumothorax is considered part of the procedure. Obtain consent for chest-tube placement while consent for the TNB is obtained, and explain that the chest tube can be omitted most of the time. Pneumothorax only occurs in 20-33% of patients undergoing TNB; this rate is interesting given that a needle is purposefully passed into the lung.

The pneumothorax is symptomatic or unstable in only approximately 20% of patients. Symptoms usually develop slowly, and the radiologist has plenty of time to calmly place a small-bore chest tube. However, the problem must be considered serious. On occasion, a patient quickly becomes gravely ill. This situation occurs in patients with little pulmonary reserve and severe chronic obstructive pulmonary disease. Of patients with TNB-induced pneumothoraces, only 1 in 5 require chest-tube placement. Therefore, only 1 in 15-25 patients who undergo TNB receive a chest tube. ^[20]

A study of 15,865 adults who had TNB of a pulmonary nodule found a 15% risk of pneumothorax with 6.6% of all biopsies requiring a chest tube. Patients aged 60 to 69 years, smokers, and those with chronic obstructive pulmonary disease had higher risk for complications. ^[21]

One relatively recent technique that has been described is the rapid needle-out patient-rollover time after transthoracic biopsy. In a study of 201 patients, this approach reduced the rate of overall pneumothorax as well as pneumothorax requiring a drainage cathether. ^[22]  However, in a larger series of 1191 patients, although this approach significantly reduced the rate of pneumothorax requiring a drainage catheter, it did not reduce the overall pneumothorax rate. ^[23]

Hemorrhage

Caution patients not to be alarmed if they cough up a teaspoonful, or even a tablespoonful, of blood. This small-volume hemoptysis is considered normal.

On the contrary, clinically significant bleeding can be a complication of TNB; however, this is rare (1 in 5300 patients undergoing TNB). ^{[4, 7]}

Needle-track seeding

Any biopsy can potentially seed the needle tract with malignant cells. During TNB, seeding occurs rarely, but is an argument against using TNB in an operable lesion with features suggestive of malignancy. ^{[7, 20, 24]}

Air embolism

A rare but potentially serious complication of TNB is air embolism to the systemic arterial tree. ^[25] Air embolism occurs when a fistula is created between a pulmonary vein and an airway. Air bubbles into the pulmonary vein, returns to the left atrium, and exits the heart by means of the aorta. The coronary and intracranial arteries may be embolized, with subsequent stroke or myocardial infarction. Recovery is possible if the patient is placed into a hyperbaric chamber to reduce the size of the bubble.

An air embolus can potentially be aspirated by using an angiographic microcatheter; however, to the author's knowledge, this has not been reported. The risk of air embolism is believed to increase in TNB of central lesions compared with TNB of peripheral lesions.