Pulmonary nodules, especially small pulmonary nodules, basically have no conscious symptoms, and patients do not come to see the doctor; detection depends mainly on physical examination or screening. Who should be screened? High-risk groups. Who are the high-risk groups? In Western countries, the high-risk group for lung cancer is long-term heavy smokers, which can be calculated by a formula. This is because there is a large difference in the incidence of lung cancer between men and women in developed western countries, smoking versus non-smoking. Therefore, smokers are considered to be the high-risk group for lung cancer, and rightly so. In China, however, the difference in lung cancer incidence rates between smokers and nonsmokers, men and women is small, and for nonsmokers, the incidence rate of lung cancer in women is also high, mainly due to the following reasons.
1, non-smokers are basically passive smokers, because your workplace and many public places and even home have people smoking, you simply can not avoid.
2, air pollution, we all live in the haze, everyone is inhaling PM 2.5, especially women, but also by the hazards of kitchen fumes. Therefore, I suggest that all people over 40 years old, regardless of gender, whether they smoke or not, should be screened for lung cancer.
What tool should be used for screening? There are many medical screening centers nowadays, but some still use chest X-ray to screen for lung cancer. This is the main reason for a large number of missed and misdiagnosed lung cancers, because lung cancers presenting as ground glass nodules (GGO) will all be missed by chest X-ray screening; lung cancers presenting as soft tissue nodules (solid nodules) will also be partially missed if they are small. Therefore, screening for lung cancer with chest radiographs must be stopped immediately, and the basic tool for screening lung cancer should only be CT or low-dose CT. Is it possible to screen for lung nodules or early lung cancer with PET-CT? PET-CT has many advantages, it can evaluate both the morphology and metabolism of the lesion, and it can scan from head to toe at one time, which is more convenient. However, if only screening for early stage lung cancer, PET-CT and normal CT are basically of the same value, because most early stage lung cancers appear as ground glass, and most of the metabolism of GGO is inactive, which mainly relies on CT at this time, so they are the same, and the charges are tens of times different.
Lung nodules detected by CT examination are both benign and malignant, more benign than malignant. Whereas many benign nodules do not require treatment, malignant lung nodules must be treated as early as possible. Therefore, a clear diagnosis must be made when a pulmonary nodule is found. If a benign nodule is misdiagnosed as malignant, the patient will suffer a knife or chemotherapy or radiation therapy for nothing, and the body will be severely damaged. If a malignant nodule is misdiagnosed as benign, it can be delayed from early to late stages and treatment opportunities are lost.
We have the ability to make a definitive diagnosis of the vast majority of pulmonary nodules because different pulmonary nodules, which grow differently, have different forms, as in everyone has a different look, and we can always find out the difference if we examine them carefully and look for them. However, the benign and malignant signs exhibited by these small nodules are very subtle, and it is necessary to adjust the scanning parameters and perform detailed computer post-processing for each patient to make the differentiation. The specific identification is based on the morphology, margins, density, internal structure, peripheral structural changes, small bronchial and small vascular changes within the nodule, and post-enhancement density changes of the nodule. Small nodules themselves are only the size of a soybean or even a green bean, and it is very difficult to distinguish these subtle structural differences among many different nodules. What to do? If the nodules are small, magnify them and look at them, but the magnification will distort the image and lead to blurring, then try to improve the resolution. There are 3 methods.
First, thin layer scanning, the thinner the layer thickness, the higher the spatial resolution, and only layer thickness less than 1 mm, the reconstructed image can achieve the effect of isotropic imaging.
Second is to reduce the scanning field (FOV), the smaller the FOV, the higher the resolution, under the premise of constant matrix.
Third, the scanning conditions are appropriately increased to improve the signal-to-noise ratio. The following were observed.
1, nodule morphology
(a) Nodules are viewed as a mass after magnification, and after reconstruction, they are observed from all aspects, like a ball placed in the hand and rolled to see that most lung cancers can be found to be lobulated, and benign nodules are mostly not lobulated.
2. Margins
Although ground glass nodules do not necessarily have burrs, their margins are often clear, or at least partially clear, even if the density is low, and the margins of infected lesions are often blurred or at least partially blurred
3.Internal structure
if the nodule is all ground glass density, most of them are benign, if partly ground glass density and partly soft tissue density, most of them are malignant, so it must be scanned in thin layers to look carefully for any soft tissue components, and there is also a kind of early lung cancer that shows granularity in cut surface.
4.Small airways within the nodules
can be narrowed and obstructed, but also not narrowed or even dilated. The most valuable sign is the limited thickening of small bronchial walls, and the imaging level is parallel to the bronchus, which is the most ideal observation.
5. adjacent pleural changes, lung cancer often causes pleural depression without thickening, and infection often leads to pleural thickening.
6, ground glass nodules with few soft tissue components, enhanced scanning and positron emission tomography (PET-CT) are not always helpful.
7, try to diagnose quickly without dynamic observation, because such small nodules observed for several years without change cannot exclude malignancy.
Finally, I would like to remind you that medicine needs theories, and diagnostic imaging physicians should have theoretical knowledge of both diagnostic imaging and clinical, experimental, anatomical and pathological theories, and mastering the above-mentioned articles may be of some help to young physicians. But by no means, you can accurately diagnose pulmonary nodules by memorizing these articles. It is difficult to make an accurate diagnosis of pulmonary nodules without carefully studying thousands of cases, because practical experience is more important for medical doctors, especially clinicians. It is extremely irresponsible to the patient to write a speculative and ambiguous report or to operate on a nodule without a clear diagnosis when you encounter it without careful examination and research.
The central idea of this paragraph is that we should and are capable of making a definitive diagnosis of most pulmonary nodules by noninvasive methods, primarily imaging, before treatment (including preoperative). The few that cannot be diagnosed definitively can be minimally invasive such as fibrinoscopy, percutaneous aspiration or thoracoscopy. It is also believed that surgery is the “ultimate method” for diagnosing pulmonary nodules. This was very popular in the 50s and 60s. In those days, if there was a lesion in the skull and the diagnosis was not clear, the skull was opened for investigation; if there was a lesion in the lung and the diagnosis was doubtful, the chest was opened for investigation; if there was something growing in the abdomen, the abdomen was opened for investigation. Because the examination technology was backward and the diagnosis level could not meet the clinical needs, “exploration” was a helpless action. Today, imaging technology has undergone a radical change, and we are fully capable of making a definitive diagnosis of pulmonary nodules using non-invasive methods. We must go forward and never go back. Of course, everything is not absolute. When individual patients cannot be diagnosed by non-invasive or minimally invasive methods, thoracoscopy or even open-chest exploration is not absolutely impossible, but it must be individual.
There is no uniform guideline in China for what kind of pulmonary nodules need to be followed up and how to follow up, but there is one in foreign countries. We do not reject what comes from abroad, we can learn from it, but we do not believe in it or copy it. For example, the Fleischner guidelines in the United States, which are currently popular in China, have six articles, one of which is not to treat nodules smaller than 5 mm, and the other five articles are to review them after 3 months and not to make a diagnosis immediately, which is obviously not suitable for our national situation. My approach is that for any patient with pulmonary nodules, we should make a clear diagnosis as soon as possible, suggest him to treat as soon as possible if it is definitely malignant, and tell him the clear result if it is definitely benign, so that he can be relieved from the panic and resume normal life and work as soon as possible. If the diagnosis is not clear from the imaging examination, we can suggest him to do minimally invasive examination such as tracheoscopy, percutaneous puncture or thoracoscopy, and the diagnosis can be clear in about one week. Those who are still unable to make a definite diagnosis will need to be followed up, so the number of people who need to be followed up is very small in my case. This is because we have the ability to make a quick and definitive diagnosis for the majority of patients with pulmonary nodules. There is simply no need to panic everyone who has a nodule for at least three months.
We must also have a tendency opinion for patients who need follow-up, and if the tendency is for infectious lesions, anti-infective treatment and a short review (2-4 weeks) may be given. Those who are inclined to benign lesions such as benign tumors and sarcoidosis may be scheduled for long interval follow-up of more than six months. Those with a clear tendency to malignancy are not followed up and are treated immediately.