chest CT scan

CT examination of the chest is a method of examining the chest by X-ray computed tomography (CT). Chest wall examination can find asbestos lung with pleural thickening not visible on the chest radiograph; if pleural effusion or mass is found in pleural effusion, it is helpful for the diagnosis of metastatic tumor and mesothelioma; can be identified according to the CT value of pleural mass Encapsulated effusion, localized mesothelioma and extrapleural lipoma; can be diagnosed by CT enhancement of chest wall hemangioma; it can well show rib fracture and rib destruction. Basic Information Specialist Category: Respiratory Examination Category: CT Applicable gender: whether men and women apply fasting: fasting Tips: Fasting for more than 6 hours before the examination, except for myocardial imaging examination. Pediatric or critically ill patients should be accompanied by medical staff. The micro-radiopharmaceutical used for diagnosing injections has no health effects on you and the surrounding people, but if you are pregnant or breast-feeding, please tell your doctor. Normal value There are more CT layers in the normal chest, and the images represented by each layer structure are different. If there is no abnormality, the doctor will write a plain lung window in the report to show that the lungs have clear texture, no abnormal distribution, and no exudation or space-occupying lesions in the lung parenchyma. The mediastinal window showed no enlargement of the two hilars, tracheobronchial patency, enhanced vascular and fat clearance, and no enlarged lymph nodes in the mediastinum. There were no abnormalities in the soft tissue of the pleura, ribs and chest wall. Clinical significance Chest wall It can be found that the asbestos lung can not be displayed on the chest radiograph with pleural thickening, and if the pleural effusion or mass is found in the pleural effusion, it is helpful for the diagnosis of metastatic tumor and mesothelioma. The CT value of the pleural mass can be used to identify the encapsulation. Fluid, localized mesothelioma and extrapleural lipoma can be diagnosed by CT enhancement, which can show rib fracture and rib destruction. 2. Lung It is valuable for the early diagnosis of peripheral lung cancer. It is helpful to diagnose central lung cancer when the main bronchus, lung bronchus and segmental bronchi stenosis or truncation. High-resolution CT (HRCT) may show diffuse interstitial that chest radiograph cannot show. Qualitative lesions are helpful for early diagnosis and differential diagnosis, as well as pulmonary blebs, bronchiectasis, and small tuberculosis voids that cannot be shown on the chest radiograph. Mediastinum It can be found that the enlarged lymph nodes that can not be found on the chest radiograph can help the qualitative diagnosis of the mediastinal mass according to the CT value and location of the mass; it can also be used to identify fatty, cystic and solid masses, and the enhanced scan can diagnose pulmonary aneurysms. And aortic aneurysm. 4. CT angiography It can be used for pulmonary angiography and has a good display of pulmonary artery branches above the sub-segment and can be used for the diagnosis of pulmonary embolism. 5.CT simulation endoscope The segmental bronchus and sub-segmental bronchus can be displayed without damage. The lesion can be observed from the distal end of the bronchial cavity and the narrow end of the stenosis. At the same time, the anatomical structure of the extraluminal can be displayed in multiple directions, and the tumor can be accurately positioned and determined. In general, chest CT scans have the following meanings: 1. Contribute to the qualitative diagnosis of the findings of X-ray chest radiography: (1) Identify the mass as cystic, substantial, fatty or calcified. (2) Determine the location and extent of the mass and identify the anatomical association between the mass and the mediastinum. 2. According to clinical needs, the hidden pathogens not found in X-ray films can be detected: (1) Finding the presence or absence of micrometastases can show the presence, location, size and number of tumors in order to formulate treatment plans. (2) CT guided percutaneous biopsy, so that some tumors can be diagnosed by histology. (3) X-ray chest radiograph and fiberoptic bronchoscopy negative, and tumor cells are positive, CT should be used to identify the intratumoral tumor source. 3. CT degree and morphology of bronchial infiltration and stenosis are inferior to X-ray tomography, and second to bronchography. 4. The discovery, localization and quantitative diagnosis of the source are reliable; the qualitative diagnosis of the solid mass is not accurate enough, and the source of the diameter below 1.5CM cannot be displayed. Precautions 1. Fasting for more than 6 hours before the examination, except for myocardial imaging examination. 2, please pay attention to diabetic patients, explain the diabetes condition to the central medical staff at the time of appointment. 3. The micro-radioactive drugs used for diagnosis and injection have no health effects on you and the surrounding people, but if you are pregnant or breast-feeding, please tell your doctor. 4, the patient must make an appointment in advance before the examination, because it can not be checked on time, please call 24 hours in advance to cancel the inspection or re-appointment time, so as not to cause drug waste. 5, children or critically ill patients should be accompanied by medical staff. 6. Bring all medical information (including medical records, laboratory results, ultrasound, ECT, CT, MRI, pathology, surgery or treatment) to the PET/CT Center on the day of the examination. Inspection process Position, breathing Routine in the supine position, arms raised on both sides of the head. Breathing should be held during scanning to avoid artifacts caused by breathing activity. Generally, deep inhalation is used to close the air. In order to make each scan time in the same respiratory phase, it is necessary to train the patient to grasp the breathing depth before scanning, and obtain a good fit of the patient. Sometimes in order to avoid the effects of blood fall in the back lung tissue to show the lesion, or to understand the fluidity of the pleural effusion, identify the effusion, you can use the prone position examination. 2. Scanning range, layer thickness and layer spacing selection The scope of the scan routinely includes the tip of the lung to the base of the lung to avoid missing lesions, typically with a continuous scan of 10 mm layer thickness and 10 mm layer spacing. A layer thickness of 5 mm or less may be used for the hilar or smaller lesions in the lung. Scanning with the same thickness and layer thickness of the same thickness does not miss the inspection organization. However, if the patient's breathing depth is not well controlled, the scanning level may be discontinuous and the inspection scope may be missed. Volumetric scanning of spiral CT avoids this phenomenon. It is generally scanned with a layer thickness of 10 mm per second and a bed speed of 20 mm per second (ie pitch=1). When the image is reconstructed, adjacent layers can partially overlap each other as needed, so that partial volume effects can be avoided and missing lesions can be avoided. High-resolution CT (HRCT), as a supplement to conventional CT, has received extensive attention in the use of chest X-ray examinations in recent years. Because it can clearly show the fine structure of lung tissue, it is mainly used for the diagnosis and identification of diffuse lesions. The basic technical conditions for achieving high-resolution lung CT are: thin-layer scanning, layer thickness 1mm to 1.5mm, using a high spatial resolution algorithm (bone reconstruction algorithm), using a 512 × 512 matrix, while using high kV and high mA Reduce image noise. The scope of the HRCT scan should be based on clinical needs. For focal lesions found in conventional CT, such as bronchoconstriction, obstruction, bronchiectasis, etc., 3 to 4 layers of HRCT can be added to the lesion, with a layer spacing of 3 mm to 5 mm or 1 cm to show the details of the lesion. Diffuse pulmonary disease should be from the aortic arch plane to the right iliac crest, with a layer thickness of 1mm ~ 1.5mm, 3cm ~ 4cm layer scan, which can show the lesions of the upper, middle and lower lung fields. 3. Scan time Short-time scanning should be used, generally 2s to 4s, and the scanning time of the new CT machine can be shortened to 1s or less. The scan time of the spiral CT is related to the set scan range. If the patient's lung function is good, the whole chest scan can be completed at one breath. If the patient can't hold the breath for a long enough time, the chest scan range can be divided into two parts, and the breath check can be completed in two breaths. However, it should be noted that the two scan ranges set should be partially overlapped to avoid the omission of the inspection site due to inconsistent breathing depth during the two breath holdings. 4. Contrast examination The purpose of contrast enhancement is to increase the contrast between the lesion and surrounding normal tissue. Because the chest has a good natural contrast, it generally does not require contrast enhancement, but for the display of vascular lesions in the chest, identify the mass in the mediastinum or enlarge the lymph nodes and large blood vessels, understand the relationship between the lesion and the blood vessels, and show the atelectasis. The size and extent of the mass can be enhanced by contrast enhancement. Generally, the bolus injection method (bolusinjection) or the rapid intravenous drip method can be used to obtain a better enhancement effect. 5. Window technology Because the structure of the chest is complex, the range of CT values ​​is wide, and the density difference between the lung tissue and the chest wall and the mediastinum is large. Therefore, two different window width window positions are required to observe the lung field and the mediastinum, that is, the lung window and the mediastinum window. . The window width of the lung window is usually 1000Hu~1500Hu, and the window position is -400Hu~-700Hu, which is suitable for displaying lung parenchyma. The window used for the mediastinum window is 300 Hu to 500 Hu, and the window position is 30 Hu to 60 Hu, which is suitable for displaying the structure in the mediastinum. High resolution CT generally uses a lung window. Not suitable for the crowd A woman who is pregnant or breastfeeding. Adverse reactions and risks May cause an allergic reaction.