In recent years, the incidence of idiopathic interstitial lung fibrosis (now called idiopathic interstitial pneumonia) has tended to increase, firstly, because of atmospheric pollution, the increase in smokers, the rampant viral abuse of antibiotics, etc., and secondly, because of the improvement in the standard of medicine and the national standard of living, the increased awareness of health care, and the increased rate of consultation. There is also a lack of awareness of idiopathic interstitial pneumonia among some health care workers, especially primary health care workers, and a lack of understanding of the consensus reached by the American Thoracic Society and the European Respiratory Society on idiopathic interstitial pneumonia after 2002, so that it is often confused with chronic diseases such as bronchiectasis, tuberculosis, and chronic bronchitis in clinical practice, and some radio and television advertisements do not distinguish between right and wrong, and the concepts are Some radio and TV commercials are so confusing that they make people laugh and cry. So the majority of people do not know the truth, blind treatment and blind medication, resulting in drug-related lung injury more serious, a waste of money, delayed treatment, damage to the body. Therefore, the author writes an article to analyze the difference between fibrosis of idiopathic interstitial pneumonia and fibrosis of bronchial dilatation, and to prompt the majority of medical patients to correctly diagnose the disease in order to prescribe the right medicine. Bronchiectasis is the destruction of medium-sized bronchial wall muscles and elastic tissues caused by chronic inflammation of the bronchi and surrounding tissues, which are replaced by fibrous connective tissue, resulting in stiffening of the bronchial walls and enlargement of the lumen, creating irreversible expansion and deformation. Idiopathic interstitial lung fibrosis is a disease of unknown cause characterized by diffuse alveolitis and disruption of alveolar structure, ultimately leading to fibrosis of the lung tissue due to an abnormal inflammatory response and excessive repair, resulting in collagen deposition and excessive proliferation of fibroblasts forming fibrotic changes. These two diseases have similarities in imaging manifestations and how to differentiate them, briefly summarized: First, due to different lesion sites, bronchiectasis lesions show distribution along the lung texture on CT, with a more pronounced directionality, and because the lesions are in the medium-sized airways, they generally do not involve the near pleura; more in the lower lobe than in the upper lobe, with the left lower lobe being the most common, and bronchiectasis due to tuberculosis is generally found in the The right upper lobe or the posterior left upper apical segment of the nodule-prone area. Idiopathic interstitial pulmonary fibrosis is dominated by alveolar lesions, or terminal airways, close to the pleura, including interlobular cleft pleura. The pathological changes are mostly bilateral and diffuse, relatively symmetric, and unilateral distribution is rare. The lesions are mostly distributed in the basal, peripheral or subpleural areas. The pathological changes of bronchial dilatation are abnormal enlargement of the bronchial lumen, thickening of the wall, relatively coarse fibrous stripe-like high-density shadow seen in the film, and sometimes fluid planes are visible in the enlarged lumen due to more secretions, such as the presence of typical cystic dilatation of the bronchus, which can present changes such as grape sign and ring sign, while columnar dilatation appears as a typical double-track sign; because the early pathological changes of bronchial dilatation Since the early pathological changes of bronchiectasis are a large number of lymphocytes in the bronchial wall and alveoli, the changes seen at this stage may not be typical of bronchiectasis, but only show local inflammatory exudative changes along the bronchial distribution, which need to be noted. Idiopathic interstitial pulmonary fibrosis due to fibrosis of the alveolar and fine bronchial walls, thickening, edema or fibrosis of the lobular septa, visible as line shadows with disorganized distribution, no clear direction, relatively fine, or grid shadows, and advanced fibrosis showing typical cystic shadows or honeycomb-like changes. If the alveolar cavity is filled with inflammatory cells and inflammatory secretions, and the alveolar wall is significantly thickened, small nodular shadows can be formed, and fusion can form lamellar shadows. If it is in the exudative stage, the lesion will appear as a ground glass shadow. Clinically, it is possible to reverse the disease with symptomatic medication in this stage. However, because the bronchial wall itself does not have obvious inflammatory edema and structural changes caused by it, the wall of this bronchial dilatation is thinner and the boundary is clearer, and because the distribution and degree of fibrotic lesions are different, the pull on the airway is not uniform, so the lumen of this kind of bronchial dilatation is more clear than that of the bronchus. The lumen of this bronchiectasis is not as regular as that of bronchiectasis. In 2009, the European Respiratory Society graded the high-resolution CT performance of IPF, and those who do not conform to IPF: predominantly upper middle lobe, predominantly peribronchial vascular, solid bronchopulmonary segments, excessive ground glass-like changes, diffuse micronodules, multiple cystic changes (away from cellular lung). Fourth, in addition to imaging, a comprehensive and exact understanding of the condition is also the focus: 1. Medical history: Most patients with bronchiectasis have a history of measles, whooping cough or bronchopneumonia that persists in childhood, and later often have recurrent infections of the respiratory tract, and such recurrent infections contribute to the onset and development of the disease. Bronchiectasis due to congenital developmental defects and genetic factors is less common. Bronchiectasis generally has a long history, with a slow onset and gradual exacerbation, and infection is the causative factor. The causes of interstitial lung fibrosis are complex and include inhalation of various dusts, toxic gases, environmental pollutants such as gasoline, smoke, animal fur, etc. It can also be secondary to diseases of the immune system and overuse of certain drugs such as chemotherapeutic agents. A significant number of cases have no clear cause and are called idiopathic interstitial lung fibrosis (idiopathic interstitial pneumonia). Repeated infections can aggravate the progression of the disease. 2. Symptoms: The typical symptoms of bronchiectasis are chronic cough, coughing up large amounts of purulent sputum and recurrent hemoptysis. It usually does not lead to severe hypoxemia unless combined with severe infection. Idiopathic interstitial pulmonary fibrosis typically presents with progressive dyspnea, irritating dry cough, coughing sputum and fever when combined with infection, but generally rarely with chest pain and hemoptysis. 3, signs: bronchiectasis signs are not specific, but persistent fixed wet in any part of the lung may suggest bronchiectasis (this wet rales are relatively turbid), and some patients (1/3) may have pestle-like fingers (toes). Idiopathic pulmonary interstitial fibrosis may be heard with a characteristic inspiratory phase wet velcro rhotic sound, or “tweed chain” sound. Due to the different pathogenesis and pathological characteristics of the two, there is a fundamental difference in treatment principles, and a rapid and accurate clinical judgment is needed to target the medication according to various means. Two cases are attached below in the hope that they may have some implications for clinical diagnosis and treatment: Case 1 Female, 50 years old, with recurrent cough and sputum for 8 years, aggravated for 1 month. On examination: mild cyanosis of the lips and mouth, jugular venous anger, large to medium blistering sounds in the left upper lung, wet rales in the left lower lung, and no obvious Velcro rales. He was diagnosed with interstitial pulmonary fibrosis and was treated mainly with Cordyceps preparations to control the disease and antibiotics when the symptoms worsened, with acceptable results, and no history of hormone application. He was diagnosed with bronchiectasis with infection and chronic bronchitis. The dorsal segment of the lower lobe of the left lung, the lingual segment of the left lung, the posterior segment of the upper lobe of the right lung, and the dorsal segment of the lower lobe of the right lung showed cystic shadow and dotted high-density shadow. A lamellar high-density shadow was seen in the lateral segment of the right middle lobe near the pleura, and a bronchial inflation sign was seen inside. The medial segment of the right middle lobe of the lung and the hilum showed cluster-like changes, as mentioned before, the grape sign or ring sign, with thicker walls, and scattered cystic shadows in the peripheral parts of the dorsal segment of the right lower lobe. Case 1 summary: The main lesions in the whole film are distributed in the middle and upper lung lobes, with less involvement in the lower lobe, along the bronchovascular distribution, involving the lung segments, with no obvious pleural-based lesions. From the imaging features, the diagnostic criteria for interstitial lung fibrosis were not met. Case 2: The patient was a 60-year-old male with recurrent cough and wheezing for more than 10 years, with little or no sputum of white color and viscous quality, and progressive worsening of wheezing. On examination: low breath sounds, velcro rales could be detected in both lower lungs. He was diagnosed with idiopathic pulmonary interstitial fibrosis, and his symptoms worsened after every respiratory tract infection. Honeycomb-like changes were seen in the upper lobe of both lungs, with the pleura as the base, especially on the left side. In the lower lobe of both lungs, the lung texture was thickened and disorganized, with diffuse fibrous striated shadow and localized latticework, and the lesions were mainly in the peripheral parts of both lungs and at the base, with a more symmetrical bilateral distribution. Case 2 summary: The lesions in the whole film were mainly in the lower lobe of both lungs, with pleura as the base and symmetrical distribution bilaterally, showing fine fibrous streak-like high-density shadow with cystic and lattice-like pattern. The lesions in the upper lobes of both lungs were honeycomb-like, but there was a more obvious difference with the bronchial dilated cystic lesions, with dense and disorganized fibrous stripe-like shadow, no obvious dilated bronchial lumen was seen, and the whole lesion was drier and slightly wrinkled. These are the author’s insights into the clinical diagnosis of bronchiectasis and idiopathic interstitial lung fibrosis, especially the differential diagnosis of imaging, which I hope will be helpful for clinical work.