Basically, the right lung has three lobes — upper, middle, and lower. The left lung has two lobes — upper and lower.
This is the basic lung diagram. In the lungs, blood comes and takes oxygen while carbon dioxide is removed. The oxygen we breathe enters the blood through the alveoli. After that, oxygen goes into the blood and carbon dioxide comes out.
Let me show the heart diagram once.
When deoxygenated blood comes from the body, it enters the right atrium through the inferior vena cava and superior vena cava. Blood from the upper body comes through the superior vena cava and blood from the lower body comes through the inferior vena cava. After entering the right atrium, the deoxygenated blood moves into the right ventricle.
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From the right ventricle, blood goes into the pulmonary artery. In the human body, the pulmonary artery is the only artery that carries deoxygenated blood. All other arteries usually carry oxygenated blood.
The deoxygenated blood goes to the lungs through the pulmonary artery. In the lungs, air comes through the bronchi into the alveoli. Gas exchange happens there, and oxygenated blood returns to the heart through the pulmonary veins and enters the left atrium.
From there, blood goes to different parts of the body including the brain, limbs, and abdomen.
Whenever a patient becomes sick, the effect is often first visible in the lungs. That is why doctors first perform an X-ray to identify the problem. Many diseases first affect the lungs.
There are many lung diseases, and learning thorax CT helps in understanding them better. Sometimes you may need to decide whether contrast is required before the radiologist advises it.
One common disease is COPD — Chronic Obstructive Pulmonary Disease. Many pulmonary patients come with COPD. Emphysema is a type of COPD. In emphysema, dark black spots appear in the lungs. Small damaged air spaces gradually become larger over time.
The lung is like a balloon. When lung tissue gets damaged, excess air gets trapped inside damaged areas. This condition is called emphysema. Air trapping and chronic bronchitis are commonly associated with COPD.
Another disease is ILD — Interstitial Lung Disease. In ILD, fibrosis develops in the lung tissue. The alveoli become damaged and oxygen-carbon dioxide exchange slows down. Because of this, the patient develops breathing difficulty.
This is an example of ILD where a large portion of the lungs is affected.
Tuberculosis (TB) is also very common in India. In early TB, the disease spreads gradually in multiple areas. Unlike some infections that remain localized, TB slowly spreads throughout the lungs.
In advanced TB, lung tissue becomes damaged. After treatment, scars remain in the affected areas of the lungs.
In CT scans, trauma patients may develop pneumothorax. Due to injury, air enters around the lungs and the lung collapses partially. This causes breathing difficulty and may become serious.
Pneumothorax can also happen after procedures like biopsy. If there is damage in the alveoli, air leaks and accumulates around the lungs.
Pleural effusion means fluid collection around the lungs.
Hemothorax occurs after injury when bleeding accumulates around the lungs. Blood appears denser and brighter than normal fluid on CT scan. Severe trauma can cause both pneumothorax and hemothorax together.
Lung masses or tumors appear as denser and brighter areas compared to normal lung tissue. If a suspicious mass is seen, contrast CT should usually be advised because tumors enhance differently than normal tissue.
Biopsy is performed by inserting a biopsy needle to collect tissue samples for laboratory testing to identify the tumor type.
Tumors may occur near the lungs, heart, or mediastinum. Tumors usually have higher density than normal tissue because they are abnormal growths.
Lung nodules are small rounded lesions. They may indicate early disease. Nodules are usually small and round, while tumors are larger and more irregular with non-sharp edges.
Metastatic lung disease means cancer has spread to the lungs. In metastatic disease, multiple abnormal areas appear throughout the lungs.
Contrast is often advised for nodules as well because enhancement patterns help identify whether they are benign or malignant.
Pleural effusion means fluid collects around the lungs, while pulmonary edema means fluid accumulates inside lung tissue itself.
Pulmonary edema damages lung tissue and fills the lungs with fluid, while pleural effusion collects outside the lungs in the pleural space.
Another trauma case showed multiple rib fractures with air entering the muscles. This is called subcutaneous emphysema.
Hemorrhage inside lung tissue may rapidly progress into hemothorax after injury, which is why trauma patients should reach the hospital quickly.
The speaker also discussed a kidney case. In kidney infection, the normal sharp outline becomes hazy. The patient’s creatinine level was high, so contrast could not be given because contrast may worsen kidney problems.
The patient also had a pacemaker.
That’s all for today’s class. More detailed videos and additional cases will be discussed in future sessions.
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