During the physical examination process, people often encounter various examination equipment, and when some people undergo lung examinations, doctors usually recommend CT scans. Many people may wonder why magnetic resonance imaging is not chosen. So, this article will lead you to understand why magnetic resonance imaging is not chosen for lung examination.
What is magnetic resonance examination?
Magnetic resonance imaging (MRI) is a diagnostic method that converts signals generated by resonance with hydrogen protons in the body through computer processing. The images obtained through magnetic resonance imaging clearly display the relationship between the lesion and surrounding important tissues, providing a good foundation for the diagnosis and treatment of the disease.
What diseases are mainly examined by MRI?
Magnetic resonance imaging examination for damage to the heart, large blood vessels, and lung mediastinum; Check for neurological damage, including tumors, infarctions, cerebral hemorrhage, congenital malformations, infections, etc; Especially spinal injuries, such as spinal tumors, atrophy, deformation, traumatic intervertebral disc injuries, etc; The diagnosis of diseases such as abdominal, pelvic, biliary, and urethral examinations is significantly better than CT. Research on diseases such as the brain and spinal cord is currently the most effective imaging technique. Early detection of tumors, cerebral infarction, cerebral hemorrhage, brain abscess, cysticercosis, and congenital cerebrovascular malformations can effectively detect conditions such as syringomyelia, sclerosis, and spinal stenosis.
For displaying intervertebral disc dislocation, degeneration, etc., the compression of nerve roots by intervertebral disc dislocation can also be clearly displayed. MRI can be used to depict clear images of the ventricles, interventricular septum, heart valves, and myocardium. Therefore, MRI examination is suitable for congenital heart disease and various cardiomyopathy. Checking for tumors in the uterus, ovaries, bladder, and prostate can stage the cancer and clearly display tumors in the liver and pancreas.
Why choose CT instead of MRI for lung examination?
Medical research has shown that lung CT examination can be chosen for lung examination, while MRI examination is not as effective as lung CT in diagnosing lung tissue lesions. Magnetic resonance imaging is a non radiative imaging examination that uses magnetic field spin imaging. Compared to CT or chest X-ray, magnetic resonance imaging is a relatively safe and radiation free examination. However, precisely because of the imaging principle of magnetic resonance imaging, which utilizes magnetic field spin activity, magnetic resonance examination is often used for solid organs with vascular systems, such as the brain, spine, liver, cardiovascular system, lymphatic system, etc., and has high diagnostic value. For organs with poor resolution, it is easy to produce artifacts. Therefore, magnetic resonance imaging is generally not used for lung examination. Of course, if used to distinguish whether lung tissue lesions have invaded adjacent vascular systems or to determine the presence of mediastinal metastases, MRI can be performed to clarify. So MRI can examine the lungs, but it cannot be used as a routine examination.
What is CT?
CT is an X-ray examination. The full name of CT is X-ray computed tomography. Computer tomography was designed by British electronic engineer Hounsfield in 1969. Compared with X-ray examination, CT can display a cross-section of a part of the human body. CT scanning is equivalent to X-ray scanning at different levels in the same area, which is then processed by a computer to obtain reconstructed images. The results indicate that sectional anatomical images have better density resolution than X-ray images. CT can enable doctors to see areas that cannot be seen by ordinary X-ray techniques, thereby detecting minor injuries. The scope of human body examination has significantly expanded, and the detection rate and diagnostic accuracy of lesions have improved. Effectively expanding the scope of human research and promoting the development of medical imaging.
CT scan of the lungs
CT scan of the lungs is a common examination method. When you seek medical attention due to cough, chest tightness, chest pain, and other reasons, the doctor will request a lung CT scan. Lung CT can scan the entire lung, chest wall, mediastinum, as well as the upper abdomen, showing partial liver and stomach. In addition, lung CT can be divided into two types: chest CT plain scan and chest enhanced CT. Enhanced CT requires injecting contrast agents into blood vessels to observe the heart and large blood vessels, in order to check blood supply. Therefore, in addition to examining the lungs, lung CT can also examine the entire chest.
Let's talk about what lung CT can check in detail:
(1) Double lungs and trachea
The CT scan of the lungs can check whether there are abnormalities in the lungs, trachea and pleura on both sides, such as pneumonia, pulmonary nodules, cancer, lung abscesses, bullae, pneumothorax, pleural effusion, pleuritis, tuberculosis, bronchiectasis, etc. Almost all lung diseases can be detected through lung CT scans. In fact, chest CT can also observe whether there is lymph node metastasis, including lymph nodes in the lungs and mediastinum.
(2) The large blood vessels of the heart
CT scan of the lungs can show whether there are any problems with the structure of the heart, whether the heart has grown, whether the myocardium has thickened, whether there are abnormalities in ventricular aneurysms, large blood vessels, pulmonary arteries, aorta, and whether there are vascular aneurysms, arterial dissections, arteriosclerosis, and so on. Special coronary CT can also see whether the coronary artery supplying the heart has atherosclerosis, arterial stenosis and the severity of stenosis, which is to judge whether there is coronary heart disease and whether coronary stents need to be placed. Coronary CT can partially replace coronary angiography.
(3) Esophageal
Chest CT can also detect problems in the esophagus, such as foreign objects in the esophagus, such as fishbones and chicken bones. Inspect esophageal diverticulum, esophageal cancer, etc. to understand the degree of tumor invasion of the esophagus, lymph node metastasis, and invasion of large blood vessels.
(4) Ribs and spine
Chest CT of bones, including ribs and thoracic vertebrae. You can observe whether there are rib cartilage tumors in the ribs, and also observe whether there are space occupying lesions and fractures in the thoracic spine.
(5) Breast and chest wall
Chest CT can see whether there are lesions in the breast and chest wall, roughly observe whether there are calcifications, tumors, breast cancer, breast prostheses, etc., but color ultrasound and mammography are preferred for breast cancer screening. You can also see whether there are lumps on the chest wall, etc.
(6) Mediastinum
The entire chest can be divided into the chest, lungs, and mediastinum. In addition to the trachea, esophagus, large blood vessels, and heart, chest CT can also detect other mediastinal issues such as thymoma, retrosternal goiter, teratoma, dermoid cyst, ganglioneuroma, etc.
In addition to these, chest CT can also show the diaphragm, upper abdomen, partial stomach, and liver. Therefore, chest CT can provide more information than regular chest X-rays, especially for early diagnosis of cancer, which is very beneficial. High resolution chest CT can detect lung nodules with a diameter less than 3mm, therefore, it is the main means of diagnosing early cancer and screening for cancer.
Finally, the above are the main introductions to why MRI examination is not chosen in lung examination. For lung examination, CT scan of the lungs is usually chosen. Because the lungs are gas containing organs, CT has significant advantages in imaging, and can better present lesions within the lung parenchyma, such as lung markings, nodules, inflammatory shadows, and emphysema, through lung CT.