April 23rd
Answers to questions about pulmonary nodules
Zhang Wei, radiology department, Jiangsu People's Hospital
Deputy chief physician and doctor of Radiology, the First Affiliated Hospital of Nanjing Medical University (Jiangsu People's Hospital). Member of neuroendocrine tumor Professional Committee of Jiangsu Research Hospital Association; engaged in image diagnosis and teaching scientific research since 2005, good at image diagnosis of respiratory system diseases, CT guided puncture biopsy and interventional treatment, and rich experience in the diagnosis of benign and malignant lung nodules and chest mediastinal lesions; in 2018, he was awarded the advanced individual of "three going to the countryside" in culture, technology and health of Jiangsu Province; He has been to Korea for exchange and study, and has participated in the national and North American annual radiology conference (RSNA) for many times. The first author has published more than 20 papers, 6 SCI papers and 1 professional book. Expert clinic time: Radiology Imaging expert clinic on Friday afternoon
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Top 1. What is pulmonary nodule? Is pulmonary nodule a disease?
Zhang Wei: pulmonary nodules refer to round or quasi round lesions in the lung. Those less than or equal to 3cm are called nodules, and those greater than 3cm are called masses. Pulmonary nodule is not the name of a disease, it is an image academic language, which can correspond to different diseases.
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Top2. What is the best examination method for pulmonary nodule screening?
Zhang Wei: common methods of pulmonary nodule screening include chest plain film and chest CT (as shown in the picture). Because of the overlap and low resolution of plain film examination, early lung lesions could not be detected. CT has a high resolution and is a spiral scan, just like cutting bread, which cuts the lung one by one, and can show very small, very light density early lesions. Therefore, CT is the best method for pulmonary nodule screening.
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Top 3. What is low dose CT? Is it safe?
Zhang Wei: the dose of CT radiation is always the most concerned topic. Many people are worried that doing CT will hurt their bodies. Let's first look at some common radiation doses. The radiation dose of a flight is about 0.03msv; the natural background radiation of each person is about 3mSv / year; the low dose of conventional chest CT radiation is about 7msv. So, what is low dose CT? It mainly refers to reducing the dose of CT radiation by reducing the kV and MAS of the ball tube. The decrease of radiation dose will lead to the decrease of image quality, which will affect the diagnosis. Therefore, the lower the radiation dose is, the better. The balance of radiation dose and image quality should be considered. In our hospital, the radiation dose of low-dose CT is about 1.5msv, which can reduce the radiation dose and ensure the image quality. So low dose CT is safe enough.
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Top 4. Why do so many people find lung nodules?
Zhang Wei: there are two main reasons: first, the incidence of pulmonary nodules is high. The lung is an organ connected with the outside world. The dust and microorganism in the air can enter the lung through the respiratory tract. The inflammatory cells in the body react and form pulmonary nodules (as shown in the figure). Secondly, the detection rate of pulmonary nodules is high. 1. Popularization of CT application and improvement of machine hardware conditions 2. Development of artificial intelligence software. Nowadays, the ability of computer-aided finding nodules is becoming stronger and stronger, which further improves the detection rate of pulmonary nodules. 3. The natural contrast of the lung is good (as shown in the figure). As we all know, the lung is full of air. The air on CT shows low density (black), while the nodule shows high density (white), so it is very easy to find the white nodule in the black gas.
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Top5. Why should we distinguish ground glass nodule, mixed ground glass nodule and solid nodule in CT report?
Zhang Wei: according to the different CT density, pulmonary nodules can be divided into three types: ground glass nodules, mixed ground glass nodules and solid nodules (as shown in the figure). Because the spectrum, diagnosis and follow-up time of three kinds of nodal diseases are different, CT reports need to be distinguished.
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Top 6. Is pulmonary nodule lung cancer?
Zhang Wei: pulmonary nodules are not the same as lung cancer. More than 90% of pulmonary nodules found in our physical examination are benign nodules, such as intrapulmonary lymph nodes, inflammatory granulomas, benign tumors, etc. However, the biological behavior of ground glass nodules, which are highly related to precancerous lesions, is very inert. 90% of the pure ground glass density nodules below 6 mm do not change in long-term follow-up, even if a few of them change in the follow-up process and then go to surgery will not affect the prognosis. Therefore, these nodules may be invasive cancer, and few need immediate surgical intervention. So when our physical examination found that pulmonary nodules do not need to panic, do not talk about the color change of nodules.
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Top 7. The size of pulmonary nodules has changed during the follow-up. What should we think about it?
Zhang Wei: Generally speaking, most of the changes of nodules are caused by various errors. The errors are caused by many factors, such as different scanning parameters of different machines, different inspiratory degrees of each examination, different measurement directions of different doctors' nodules, different measurement directions of the same doctor, etc. Therefore, we must exclude the above factors that may cause the error of nodule diameter, so as to make clear the change of nodule size in the true sense. Therefore, it is suggested that patients should follow up in the same hospital and in the same person as far as possible, so as to reduce the error as much as possible.
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Top8. How long does it take for patients with pulmonary nodules to have CT follow-up?
Zhang Wei: the follow-up time needs to be determined according to different situations. For example, for solid nodules that can be confirmed, it is recommended to follow up one year later; for solid or mixed solid nodules that cannot be determined the nature of the lesions, it is recommended to recheck every 1-3 months after oral antibiotics; for ground glass lesions, follow-up every 6-12 months is recommended. Therefore, the follow-up time of nodule needs the guidance of professional doctors, not too frequently, and never be indifferent.
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Top9. Why is it particularly difficult to diagnose pulmonary nodules with CT film in the hospital? How to solve it?
Zhang Wei: because the pulmonary nodules are usually small, often in a few millimeters, the film image of the hospital is too small, and it is difficult to find the nodules of a few millimeters like looking for a needle in a haystack. Even if it is barely found, because the layer thickness of the printed image is thick, it is impossible to accurately evaluate the density, shape and other details of the nodules, so the CT brought by the patients in the hospital can only be used as a reference. It is generally recommended that patients copy the thin-layer data of the local hospital electronic version, or reexamine CT in our hospital.
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Top 10. What is the application of CT puncture for pulmonary nodules?
Zhang Wei: first, the ground glass nodule that needs to be removed by surgery should be precisely located before operation. Under the guidance of CT, the wire hook was placed around the focus, and methylene blue staining was injected to facilitate the surgical resection (as shown in the figure). 2、 Biopsy of solid nodules. 1. For solid nodules that are difficult to be determined, the biopsy should be clear about the pathology; 2. For tumor patients who have no chance of surgery in the late stage, the biopsy should be clear about the pathology and gene detection results. 3、 It is not recommended for the biopsy of ground glass nodule, because the ground glass lesion is not dense enough, it is difficult to obtain the desired positive results by puncture, and it is also easy to have hemoptysis and other complications.