A transthoracic needle aspiration (TTNA) is done to check if a growth in the lung is cancer. This abnormal growth, called a solitary pulmonary nodule (SPN), may be found during a chest X-ray or CT scan.

TTNA uses a long needle inserted through the chest wall between the ribs to take a tissue sample (biopsy). The needle usually is guided to the right spot in the lung with the help of a CT scan. A pathologist checks the sample under a microscope to see if it is cancer.