Tuberculosis is a chronic infectious disease caused by mycobacterium tuberculosis, which is seriously harmful to health. among the legal infectious diseases, the number of patients is only second to viral hepatitis, which is still a serious public health problem. Tuberculosis bacteria can invade multiple organs of the human body, such as lungs, lymph nodes, pleura, bone joints, skin, meninges, kidneys, etc. Among them, tuberculosis is the most common, accounting for more than 80% of all types of tuberculosis.
1、 Symptoms of pulmonary tuberculosis: If coughing, expectoration for more than 2 weeks, hemoptysis or bloody sputum occur, be alert to pulmonary tuberculosis, which is a manifestation of tuberculosis bacteria damaging lung tissue. But if the condition is mild, the inflammatory exudate is not obvious, and the nervous system does not report to the cough center, coughing and expectoration will not occur.
In addition, tuberculosis may also be accompanied by symptoms such as chest tightness, chest pain, low-grade fever, night sweats, fatigue, decreased appetite, and weight loss.
Tuberculosis is the main cause of death from a single infectious disease in the world, especially in low - and middle-income countries. China is still one of the countries with high load of tuberculosis, and we should constantly focus on the prevention and control of tuberculosis. Below, we will focus on the CT characteristics of active tuberculosis, hoping to be helpful to friends.
2、 Judging whether tuberculosis is in an active phase
There are two important meanings in judging whether tuberculosis is in an active phase: whether to treat it or not and whether to stop taking medication.
Active tuberculosis is contagious and can cause sustained damage to lung tissue, requiring timely and standardized treatment; For patients whose treatment is about to end, the absorption of the lesion should also be evaluated to determine whether to discontinue the medication and complete the treatment.
Sputum smear examination is easy to operate and cost-effective, but has poor sensitivity; The sensitivity of sputum culture is high, which is the gold standard for laboratory diagnosis of tuberculosis, but the detection cycle is long; In recent years, the molecular biology diagnostic technology of tuberculosis etiology has made rapid progress, which has cleared the fog for many difficult cases. CT films are very important for the diagnosis of active pulmonary tuberculosis:
3. What are the signs of active pulmonary tuberculosis on CT films
1. Pulmonary tuberculosis causes necrosis and liquefaction of lung tissue. After sputum is coughed up through the bronchi, cavities are formed in the diseased lung lobes, and drainage bronchi are often visible. Due to tuberculous inflammation, the bronchial wall is thickened.
2. Multiple clusters of small nodules (fireworks sign), tree bud sign, centrilobular nodules, ground glass opacities, halo sign, pulmonary consolidation, nodules or masses with central necrosis, etc;
3. Lymph node enlargement and pleural effusion.
There are multiple black cavities, thickening of the draining bronchial wall, blurred nodular shadows, and pulmonary consolidation, which are typical active pulmonary tuberculosis. They are infectious, and a large number of tuberculosis bacilli can be found in sputum. It is important to maintain isolation from family members and avoid spitting on the ground.
These three situations are in the active stage, contagious, and require timely and standardized treatment for prevention.
Mycobacterium tuberculosis has strong survival ability and can survive for 6-8 months in dry sputum. It attaches to dust particles and can maintain infectivity for 8-10 days. However, it has weak resistance to dampness, heat, ultraviolet radiation, and ethanol. It can die within minutes of exposure to 75% alcohol in direct sunlight for 2-3 hours.
4、 What CT signs indicate that pulmonary tuberculosis is in a stable phase?
The occurrence of calcification in pulmonary tuberculosis nodules, residual cord shadows in the lungs, pleural calcification, long-term stable purifying cavities, or calcification of cavity contents, stable residual bronchial damage (such as bronchial torsion and dilation), etc., indicates that pulmonary tuberculosis is in a stable phase.
For some cases of pulmonary tuberculosis that cannot be determined whether it is active or not, PET-CT can be considered if conditions permit. It has unique value, especially in diagnosing subclinical tuberculosis patients, early recurrence of old pulmonary tuberculosis, evaluating treatment response, etc. It is very meaningful, but it is more expensive and not suitable for popularization.