From the Guidelines
Ultrasound-guided transthoracic needle biopsy (US-TTNB) is indicated for diagnosing peripheral lung lesions that are in contact with the pleura, chest wall masses, pleural-based lesions, and mediastinal masses that are accessible via the chest wall, as it provides high diagnostic yield with sensitivity ≥ 90% for peripheral nodules, especially when the lesion has pleural contact, minimizing the risk of pneumothorax 1. The main indications for US-TTNB include:
- Evaluation of suspicious pulmonary nodules or masses
- Assessment of metastatic disease
- Diagnosis of infectious processes like tuberculosis or fungal infections Contraindications to US-TTNB include:
- Severe pulmonary hypertension
- Bleeding diathesis (INR >1.5, platelet count <50,000/μL)
- Mechanical ventilation
- Severe emphysema or bullous disease along the needle path
- Suspected vascular lesions
- Inability of the patient to cooperate with breathing instructions or maintain position Relative contraindications include:
- A single functioning lung
- Severe COPD
- Previous pneumonectomy The procedure is preferred when the lesion has pleural contact, as this minimizes the risk of pneumothorax by reducing the amount of aerated lung traversed, and it offers advantages of real-time imaging, absence of radiation exposure, lower cost compared to CT-guided procedures, and the ability to perform the procedure at bedside for critically ill patients 1. However, its utility is limited to lesions with pleural contact, as ultrasound cannot penetrate air-filled lung tissue, and the diagnostic yield may be affected by nodule size, needle size, the number of needle passes, and the presence of on-site cytopathologic examination 1. It is essential to consider the patient's comorbidities, preferences, and the estimated pretest probability of malignancy when deciding on the procedure, and a multidisciplinary approach aligned with current guidelines is strongly encouraged 1. The most common complication of US-TTNB is pneumothorax, and rates vary in series based on technique and study design, with reported rates ranging from 9% to 54% 1. A negative biopsy result does not exclude malignancy, but US-TTNB is valuable when a definite benign diagnosis is confirmed, and a biopsy result can also be nonspecific benign or nondiagnostic, in which case continued surveillance or repeat biopsy need to be considered depending on clinical concern for malignancy and the patient’s comorbidities and preferences 1.
From the Research
Indications for Ultrasound-Guided Transthoracic Biopsy (US-TTNB)
- Peripheral lung lesions and pleural masses are suitable for US-TTNB, as stated in the study by 2
- Mediastinal lesions can also be diagnosed using US-TTNB, with a high diagnostic accuracy of 96% and sensitivity of 95%, as reported by 3
- US-TTNB can be used for lesions abutting the pleural surface, as mentioned in the study by 4
Contraindications for US-TTNB
- No specific contraindications are mentioned in the provided studies, but the study by 5 mentions that a systematic step-by-step guide for performing US-TTNB should be followed
- The study by 4 excludes lesions that are not suitable for image-guided transthoracic needle aspiration (TTNA), such as those that require fluoroscopic guidance or rapid on-site evaluation (ROSE)
Factors Affecting Diagnostic Yield
- The depth, width, and pleural contact of the lesion, as well as the number of biopsies, are key variables associated with diagnostic yield, as reported by 2
- Lesion size is also a factor, with smaller lesions (≤ 20 mm) having a higher risk of nondiagnostic biopsy results, as stated by 6
- The final diagnosis of benignity is also a risk factor for nondiagnostic biopsy results, as mentioned in the study by 6
Complications of US-TTNB
- Pneumothorax, hemoptysis, and sepsis are potential complications of US-TTNB, with pneumothorax being the most common, as reported by 2
- The risk of pneumothorax is associated with lesion depth, and the risk of sepsis is associated with the number of biopsies, as stated by 2
- The overall complication rate for US-TTNB is relatively low, with a pooled rate of 4.4% for pneumothorax, as reported by 4