Although percutaneous needle biopsy of the lung can be performed with only local anesthesia, conscious sedation is useful because it allows patients to breathe regularly and remain motionless. It is particularly helpful in anxious patients and elderly patients (who have arthritic complaints and cannot lie still), for biopsies of small lesions in the lower lobes near the diaphragm, or for lesions near large central vessels. We routinely use midazolam and fentanyl in almost all of our biopsy cases.

CT is the technique of choice for guiding percutaneous needle biopsy of the lung because it allows clear visualization of pulmonary abnormalities and adjacent structures. Because of increased awareness of significant radiation exposure to the patient during CT-guided procedures [9], we have taken measures to reduce the radiation dose by decreasing the kVp and mAs during intraprocedural image acquisition, particularly after the initial scan to localize the lesion and plan the needle trajectory. Further dose reduction can be achieved by reducing the z-axis coverage to 5–7 slices at 2.5-mm intervals. CT fluoroscopy is increasingly used because of its advantage of real-time visualization during needle manipulation, particularly for difficult lesions [5]. The main disadvantage of CT fluoroscopy is radiation exposure to the operator. Ultrasound guidance can be used for peripheral lesions.

The patient is positioned in the supine or prone position to avoid crossing the interlobar fissure with the biopsy needle, thus reducing the risk of pneumothorax (Fig. 1A, 1B, 1C). When possible, the prone position is preferred because the posterior ribs move less than the anterior ribs, the posterior intercostal spaces are wider, prone positioning prevents the patient from visualizing the needle during the procedure, and the patient can recover in the more comfortable supine position. The oblique and decubitus positions are less stable than supine or prone positions but can be considered as an approach into a subpleural lesion in the lateral aspect of the lungs to avoid transgression of normal pulmonary parenchyma.

The lesion is localized and the access route is planned using CT images of 2- or 3-mm slice thickness. Care must be taken to avoid chest wall vessels, including the internal mammary, axillary, subclavian, and intercostal vessels, as well as central vessels (Fig. 2). The intercostal vessels are sometimes difficult to identify on unenhanced CT images, but they course along the inferior aspect of the ribs. Peripheral lesions can frequently be biopsied without traversing normal lung tissue to avoid pneumothorax. Large bullae should be avoided. The needle trajectory should be directed away from important structures, such as the aorta, heart, or large pulmonary arteries (Fig. 3). When performing percutaneous needle biopsy of the lung of a mixed-attenuation lesion, sampling of the solid portion is preferable. When the lesion contains central necrosis or cavitation, one should aim for the wall of the lesion (Fig. 4). When a lesion is located in the inferior portion of upper lobes, a posterior approach can sometimes still be used by angling of the CT gantry, which allows a superior needle entry point with caudal angulation of the needle over the major fissure (Fig. 5A, 5B). Similarly, gantry angulations allow needle entry at an intercostal space superior or inferior to a lesion when the needle path is otherwise obstructed by a rib.

Coaxial technique is preferred at our institution because it allows multiple samples to be taken with a single pleural puncture. The introducer, a 19-gauge ultrathin needle that accommodates a 20-gauge core biopsy needle, is carefully aligned by advancing it in small increments in the chest wall before puncturing the pleura. Once the introducer needle is satisfactorily aligned, a single deliberate puncture is made to advance the introducer well beyond the pleura into the lung. If adjustment is necessary, the introducer can be repositioned without exiting the lung, thus limiting the number of pleural punctures to one. The introducer should be advanced into the periphery of the lesion.

Once the position has been confirmed, the inner stylet of the introducer needle is removed. Drops of saline can be placed in the well of the introducer needle to form a water seal to prevent air from entering the needle. A 22-gauge Chiba needle attached to a 10-mL syringe can then be advanced through the introducer needle for aspiration by agitating the needle up and down through the lesion with a jabbing motion while applying suction (Fig. 6). The needle aspirate is then sprayed on the surface of a glass slide and handed rapidly to a cytotechnologist to avoid “air-drying” of aspirated cells. At our institution, the cytologist is available for rapid interpretation, which provides the radiologist with information regarding the cellularity of the sample and presence of malignant cells. If a specific diagnosis is not obtained, repeat aspiration or core biopsy is performed. The aspirated samples can be collected by pushing sterile normal saline solution through the Chiba needle into a container. This fluid can then be processed into a cell block for pathologic examination.

Core biopsies can be taken through the same introducer needle using a 20-gauge core biopsy needle with 1- or 2-cm needle throw. Studies have shown better diagnostic yield with core needle biopsy compared with fine-needle aspiration, particularly in establishing benign diagnoses such as hamartoma, granuloma, and sarcoidosis [10–13], without an excess of complications [10, 13]. Core biopsy samples are placed in formalin in most cases. In cases of suspected lymphoma, the samples are placed either in normal saline or RPMI solution (Roswell Park Memorial Institute) for flow cytometry. In cases in which infection is suspected, inflammatory cells are noted, or if a specific diagnosis is not made during rapid interpretation of cytology, a sample should be sent to microbiology.

Immediately after removal of the introducer needle, the patient is swiftly rolled onto the stretcher into a biopsy side-down position and transferred to the postprocedure care area. Talking, moving, and coughing are discouraged to prevent pneumothorax. Oxygen is administered at 2 L/s by nasal cannula. The patient's heart rate, respiratory rate, blood pressure, and oxygen saturation level are monitored during the 3-hour recovery period. Chest radiographs are usually obtained at 1 and 3 hours after the procedure to check for the presence of pneumothorax or hemorrhage.