This is a video of a CT-guided transthoracic percutaneous fine needle aspiration. The aspiration will be performed on a tumor suspect lesion in the mid lobe of a patients right lung. The procedure start by taking a CT-scan of the area. Based on the CT images a puncture canal is planned. The radiographer measures and marks the correct puncture point on the patient. It is beneficial to puncture only one lobe of the lungs. The patient’s thorax is disinfected and covered with a sterile surgical drape. Local anasthesia is administered. The needle is inserted a few centimeters deep, and some anasthetic is injected. A new CT scan is done, to check that the needle is aimed in the correct direction. The needle is pushed deeper, and the direction is controled again with a CT scan. This is repeated until the needle reaches the plura, which is visible here. The rest of the anasthetic is injected and the needle is removed. A small insition is made in the skin, with a scalpel. An introducer needle, with a sharp pointed trocar, is inserted in the incision. The same method is used to insert this needle as with the anasthesia. The introducer is gradually inserted, and the direction is controlled using CT. The needle is pushed through the plura and in to the lesion, which is visible here. The sharp pointed trocar is removed from the introducer, and the aspiration needle is incerted. The radiologist uses a syringe to aspirate, and simultaniously move the needle up and down in the lesion. This is the needle in the lesion after aspiration. There is some bleeding. The aspiration material is carefully placed on a slide. Another slide is used to smear the material. The material is collected with the slide on one end, and then smeared out with one quick constant movement. The material is dried under a fan before staining. The slide is dipped five times in a fixation fluid with methanol. Then three times in the first staining bath, and six times in the second staining bath. before rinsing in two baths of pure water. Immidiatly after stianing, the specimen is viewed under a microscope, with a 10 or 20 magnification lens.