Interventional Techniques

Chapter 19 Interventional Techniques

Several interventional techniques are performed in thoracic radiology. The most important is percutaneous transthoracic needle biopsy (TNB) of lung and mediastinal lesions. Other interventional procedures that are mostly related to the pleura include drainage of fluid collections, catheter drainage of pneumothoraces, and sclerotherapy.



Transthoracic needle biopsies (Box 19-1) are performed most commonly for the diagnosis of an indeterminate solitary pulmonary nodule. Not all solitary pulmonary nodules that are suspect for bronchogenic carcinoma require biopsy. If the pretest probability is very high for lung cancer or a biopsy is unlikely to have any impact on management, TNB should not be performed. For example, if a patient presents with a long history of smoking and a new, irregular, spiculated nodule in the lung, the likelihood is extremely high that this represents a lung cancer, and it is reasonable to proceed directly to staging and resection. Other indications for TNB include undiagnosed mediastinal masses, a hilar mass when the bronchoscopy result is negative, single or multiple pulmonary nodules in a patient with a known extrathoracic malignancy or a suspicion of metastatic disease, and suspected infectious lesions manifesting as solitary nodules, masses, or very focal areas of consolidation, particularly in the immunocompromised host.

There are several diagnostic alternatives to TNB. The most important is bronchoscopy. However, bronchoscopy is preferred for central lesions, particularly if a prebronchoscopy CT scan shows evidence of endobronchial involvement. Transthoracic biopsy may be used to diagnose hilar masses when the result of bronchoscopy is negative and extraluminal compression of the airway is identified. Transbronchial needle aspiration (i.e., Wang needle) is primarily used to establish metastatic malignancy in mediastinal nodes for the purposes of staging lung cancer. A needle is inserted using the bronchoscope through the tracheal wall or carina to facilitate the biopsy of the nodes. In the absence of a visible endobronchial lesion, the diagnostic yield for bronchoscopy in peripheral nodules is low (in the range of 58% to 80%) and is lowest for nodules less than 2 cm in diameter. Video-assisted thoracoscopy enables the diagnosis of peripheral subpleural pulmonary lesions. However, this is an operative procedure that requires an inpatient stay and general anesthesia, and it is more expensive than bronchoscopy or transthoracic needle aspiration biopsy.


Most contraindications to TNB are relative rather than absolute (Box 19-2). The most important are bleeding diatheses. A prebiopsy prothrombin time (PT), partial thromboplastin time (PTT), and platelet count are recommended. A careful history of coagulation abnormalities or the ingestion of drugs such as aspirin, which may lead to abnormal platelet function, should be obtained. Patients with low platelet counts who require an emergent biopsy, such as an immunocompromised patient with pulmonary infection, can receive platelet transfusions. Biopsy of lesions that have a marked vascular supply should be avoided.

Another relative contraindication is pulmonary hypertension. Needle biopsy can be safely attempted in patients with mild pulmonary hypertension if the nodule is peripheral. In the case of deep nodules or hilar masses, it is not recommended. Other relative contraindications include mechanical ventilation, bullae, or severe emphysema in the path of the lesion to be biopsied, severe chronic obstructive pulmonary disease (COPD, defined by a forced expiratory volume in 1 second [FEV1] of less than 1 L), and intractable cough.

Patients should be cooperative and be able to maintain a certain position. Biopsies are performed with patients in the supine or prone position. The decubitus position is less preferable because it is difficult for the patients to maintain the position.


Technical Factors

The shortest, most vertical biopsy path should be chosen based on the prebiopsy CT scan (Fig. 19-5). Interlobar fissures, pulmonary vessels, bullae, and areas of severe emphysema should be avoided (see Fig. 19-1). Sometimes, this can be achieved by tilting the CT gantry (Fig. 19-6). Paraspinal and extrapleural saline injection creates safer access to paramediastinal lesions (Fig. 19-7). The patient is placed in a position that provides a safe approach—prone, supine, or occasionally, decubitus—as indicated. After a scanogram is performed, thin-section, 2- to 5-mm CT slices are obtained through the lesion with a localizing grid in place on the skin overlying the lesion. A desired skin puncture site is identified using the grid, and the patient is prepared and draped in a sterile manner. After the injection of local anesthesia, a small puncture is made in the skin and subcutaneous tissues with a scalpel.

An introducer 19-gauge spinal needle is advanced through the chest wall using intermittent CT scans to verify the position of the needle. When performing TNB, the introducer needle must be perfectly aligned with the lesion before the pleural puncture. It is difficult to reposition or reorient the path of the needle after the lung is entered. Attempting to do so often produces a pleural tear.

Although the biopsy needle may be introduced alone, we prefer a coaxial technique. The 19-gauge introducer spinal needle is placed through the skin and chest wall and through the pleura just adjacent to or into the lesion to be biopsied. A 21- or 22-gauge aspirating needle is then used for the biopsy, and it is placed by way of the introducer needle. Ultrathin, 19-gauge introducer needles can accommodate 20-gauge automatic biopsy devices for core specimens. The coaxial technique allows several specimens to be obtained with only one pleural puncture.

After the introducer needle has been correctly positioned immediately adjacent to or in the lesion, the stylet is removed, and the 21- or 22-gauge aspirating needle is placed through the introducer needle into the lesion. A 10-mL syringe is then attached to the thin needle, and using a series of up and down and rotatory motions, an aspirate is obtained. The specimen should be immediately placed on glass slides and fixed with a number of available quick stains. If a core biopsy is used, the tissue can be rinsed with formalin or saline. A small amount of saline is placed in the introducer needle before withdrawing the stylet to reduce the risk of air embolism and reduce friction between the needles. If the cytologist thinks the original pass with the aspirating needle is nondiagnostic or negative, additional samples may be taken, as well as core samples, using the coaxial technique. If inflammatory changes are present or there is a suspicion of active infection, specimens should be sent to the bacteriology laboratory.

Feb 28, 2016 | Posted by in RESPIRATORY IMAGING | Comments Off on Interventional Techniques
Premium Wordpress Themes by UFO Themes