What are the differences between a normal chest X-ray and an abnormal chest X-ray?

From a clinical perspective, some patients with lung or heart discomfort will choose to take a chest X-ray for examination, but they will not look at the results themselves after they come out. They need to see a professional doctor to determine the final condition. Experts say that in order to correctly distinguish between normal chest X-rays and abnormal chest X-rays, one can start from several aspects, such as counting the ribs, judging the lung texture, mediastinum and hilum, heart, diaphragm and costophrenic angle, and nipple position.

1. Count the ribs

Counting ribs is the basis of reading X-rays. Using ribs as landmarks, the ribs in a normal chest X-ray are counted from the upper back to the lower front. The first rib and clavicle form a quasi-circular translucent area, which is also the area where the apex of the lung is located. Comparison between the two sides is helpful in discovering lesions at the apex of the lung.

2. Determine lung texture

One side of the lung field is divided into three equal parts from the hilum to the periphery of the lung, called the inner, middle and outer zones of the lung respectively. Under normal circumstances, the inner and middle zones of the lung have lung texture, while the outer zone does not. If lung texture appears in the outer zone, it means that the lung texture has increased. Conversely, if the transparency of the inner and middle zones increases, the lung texture has decreased. The distinction between the inner, middle and outer zones of the lungs also has another meaning, which is to judge the lung compression in emphysema. Generally speaking, the inner, middle and outer zones of the lungs account for 60%, 30% and 10% of the lung volume respectively.

3. Mediastinum and hilum

In front of the hilum, it is at the level of the second to fourth intercostal spaces; posteriorly, it is at the level of the spinous processes of the fourth to sixth thoracic vertebrae, and on the vertical line at the midpoint of the line connecting the posterior median line and the medial edge of the scapula. What is the significance of this? For example: in fibrocavitary pulmonary tuberculosis, there is "hilar hanging". If you know the position of the normal hilum, it is easy to determine whether it is hilar hanging. Regarding the mediastinum, the main thing to do is to determine whether there is displacement.

4. Heart

There are five to eight thoracic vertebrae behind the heart and two to six ribs in front of the heart. The aortic knot is the place where the aortic arch turns from right to left and protrudes from the left edge of the sternum. It is level with the second costal cartilage of the left chest. The pulmonary artery segment is located below the aortic junction and is very meaningful in determining pulmonary hypertension.

5. Diaphragm and costophrenic angle

Generally, the right costal diaphragm is at the level between the front end of the fifth rib and the front end of the sixth rib. Due to the presence of the liver on the right side, the right diaphragm is usually one to two centimeters higher than the left side. Significance: Changes in chest or abdominal pressure can change the position of the diaphragm. For example, the diaphragm can be lowered in case of pneumothorax; paralyzed phrenic nerve can cause paradoxical breathing. The normal costophrenic angle is sharp. If the costophrenic angle becomes blunt, there is fluid or blood in the chest cavity.

6. Nipple Position

This is also a problem we often encounter. Male nipples are generally located between the fifth ribs, while female nipples may be located lower. Asymmetrical nipple shadows on both sides can easily be misdiagnosed as nodular lesions.