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Imaging examinations are essential during physical examinations and are often the first choice when there is discomfort in a certain part of the body.

Ultrasound,CT, X-ray,MRI…There are many types of imaging examinations, which sometimes overlap, and diseases in different parts of the body actually have the best options when it comes to examination and diagnosis.

If you go to the hospital for a check-up when you feel unwell, how should you choose different parts of your body?

◉CT examination: the first choice for brain diseases

CT examination can detect most brain diseases, including congenital brain development and intracranial abnormalities, brain tumors, cerebrovascular diseases, craniocerebral trauma, etc.

However, the value of CT is limited for certain brain degenerative diseases, smaller lesions such as pituitary microadenomas and small metastases, and various diseases within the spinal canal (including the spinal cord).

◉MRI (Magnetic Resonance Imaging): A Complement to CT

MRI can be used as the first choice examination for acute cerebral infarction, brain metastasis, etc., and is an important supplement to CT examination. For intraspinal diseases that cannot be detected by CT, MRI is the first choice examination technology.

◉Vascular ultrasound: the first choice for vascular examination

The smoothness of the blood vessel wall, the degree of intimal thickening and plaques can be observed, but the diagnosis of acute cerebrovascular disease is still the first choice for cranial CT examination to diagnose whether there is cerebral hemorrhage. After excluding cerebral hemorrhage, MRI can be selected to diagnose whether there is new cerebral infarction.

◉X-ray: the first choice for bone and joint diseases

Because many bone and joint diseases, such as inflammation and early tumors, have X-ray manifestations that appear later than pathological changes and clinical symptoms, the initial examination may be negative, and regular follow-up or further CT or MRI examinations are required.

◉CT examination: Differentiating soft tissue diseases

CT is another important examination for bone, joint, and soft tissue diseases, and it is easier to distinguish between lesions such as cancellous bone and cortical bone destruction, dead bone, calcification, and ossification.

◉MRI: Better than CT

Since the density of soft tissues such as muscles, blood vessels, nerves, and joint capsules is not very different, X-rays cannot distinguish them, and MRI is significantly better than X-rays and CT. Therefore, MRI is preferred when tumors, necrosis, hemorrhage, and edema are suspected.

◉Cardiac ultrasound: good at observing structural lesions

Cardiac color ultrasound can display the heart structure and movement status in real time and dynamically, and perform analysis to understand the heart condition, but it is difficult to clearly display the coronary arteries.

◉CTA (Coronary CT Angiography): Diagnosis of coronary heart disease

As an invasive technique, coronary angiography is the gold standard for diagnosing coronary heart disease. It can observe soft plaques and calcifications on the coronary artery walls, as well as the range and degree of coronary artery stenosis, and provide treatment plans.

◉X-ray: Lung examination

X-ray examination is the first choice for routine physical examinations, general respiratory diseases or preoperative routine examinations for people under 40 years old. However, lung tissue is easily overlapped and blocked, and X-ray radiation dose is small and density resolution is low, making it difficult to detect certain small lung lesions or lesion details, which can easily lead to missed diagnosis.

◉CT examination: nodules, tumors related

If X-rays reveal abnormalities, further chest CT examination is required; chest CT examination may be the first choice for reexamination of small lung nodules, screening of people at high risk of lung cancer, searching for primary lung lesions after metastases are discovered, and staging of lung cancer patients, etc., to provide richer lesion information.

◉Gastroscopy and colonoscopy: the gold standard for diagnosing digestive tract diseases

For digestive tract diseases such as the esophagus, stomach, and intestines, endoscopic examinations such as gastroscopy and colonoscopy are the gold standard for diagnosis.

◉X-ray: Acute abdomen

X-ray is the first choice for acute abdomen caused by the digestive tract. It can be diagnosed quickly, but it is difficult to determine the cause.

◉CT scan: digestive tract tumors

CT scans are fast and cause little interference with gastrointestinal motility. They can clearly display the digestive tract wall, the outside of the lumen, and the surrounding organ structures, and can provide more information for diseases such as digestive tract tumor staging, acute abdomen, and mesenteric lesions.

◉Ultrasound: Relatively common

The liver, pancreas and spleen are solid organs, while the biliary system is a hollow organ. Ultrasound is one of the most commonly used devices for examining lesions in these areas.

Ultrasound can accurately distinguish between cystic and solid lesions; enhanced ultrasound examination can reflect the blood supply of the lesion to a certain extent; color Doppler ultrasound can observe the blood flow speed and direction in the blood vessels within the lesion and surrounding areas.

◉CT or MRI: Further clarification

If ultrasound finds pancreatic abnormalities, CT or MRI examinations are required to clarify the nature, extent and secondary changes of the lesion. The disadvantage of ultrasound is that it is not very accurate in judging the blood supply and qualitative diagnosis of lesions, and it is difficult to find lesions with a diameter of less than 1 cm.

◉Ultrasound: high stone detection rate

Ultrasound can detect and diagnose most urinary system lesions and has a high detection rate for stones, but it is difficult to diagnose smaller lesions (small stones or small tumors, etc.) and ureteral lesions without obstruction.

◉CT: the most important and most commonly used

When going to the radiology department for an examination, patients are asked to take off necklaces, earrings, hairpins, etc., and are sometimes asked "Are you wearing makeup?" Why are there so many rules for imaging examinations?

The Radiology Department is responsible for X-ray, CT, MRI and other examination items. It has many equipment and requirements, each of which is for the protection of patients.

For example, during an MRI scan, the cylinder-like device is actually an oversized strong magnet that emits high-energy radio frequency pulses, like a giant magnet;

Brooches, hairpins, etc. can be sucked into the center of the magnetic field at high speed and turned into sharp weapons in seconds, which can damage the machine at the least and threaten the patient's life at the worst.

Although X-ray and CT examinations are non-magnetic, it is also required that metal should not be worn. Otherwise, abnormal images with metal foreign bodies as the core will remain on the image, namely "metal artifacts", which will not only obscure normal human tissues, but also form large shadows, making the image impossible to observe.

If the examination is of the cranial and brain systems, in addition to not allowing the wearing of jewelry such as hairpins and earrings, the examinee may also be told to try to keep his or her face free of makeup.

This is because some cosmetics, nail polish, sunscreen, and hair wax contain metal components that can react with magnetic fields or directly interfere with imaging results.

In addition, the high-energy radio frequency pulses of magnetic resonance can produce a thermal effect. In addition to heating necklaces, bracelets, earrings, magnetic therapy underwear and other objects, the pigments used in tattoos, eyebrow tattoos, and eyeliner tattoos can also heat up.(Containing metal components)This is no exception, especially for large-area tattoos, which can cause skin irritation or even burns, so be sure to inform your doctor in advance.

In fact, except for imaging examinations such as CT and MRI, clinical advice is that it is best not to wear makeup during physical examinations.

Because many diseases can be detected through abnormalities in facial skin, lips, nails, etc., makeup will change the true state of the face while changing the skin color, affecting the diagnosis of the disease. ▲

Editor of this issue:Xu Menglian