Diagnostics is the field of medicine, which studies the signs of illness, the methods and principles of diagnosis. Modern medicine knows the possibility of diagnosis, such as:

• X-ray;
• Ultrasound;
• CT - Computer tomography;
• MRI - Magnetic-Resonance imaging;

X-ray

An X-ray test uses small doses of X-rays, which are a type of high-energy (ionizing) radiation.  X-rays are the oldest and most frequently used form of medical imaging.

Ordinary X-ray test can be used for diagnosingdisease and abnormalities of bones, teeth, joints, lung, gastroenterologysystem or breast (mammography).

The test is easy, quick, painless and relatively cheap. On the other hand, an ordinary X-ray has limited use. More sophisticated iodine-based and barium contrast X-rays, or other imaging techniques may be needed for detailed or further estimation of certain body parts.

The dose of X-ray radiation used during the test is always kept to the minimum needed to obtain a good picture of the particular body part being checked. However pregnant women should not have an X-ray test, as there is a small risk that X-rays may cause an abnormality to the fetus.

Ultrasound scan

An ultrasound scan is a very commonly held test, which uses high-frequency in audible sound waves to create images of organs and structures inside your body. As it uses sound waves and not radiation, it is thought to be very safe. 

The scan is painless and takes about 15-45 minutes, depending on which parts of the body are being examined. A record of the results of the test can be made as still pictures or as a video recording.

It can help to determine the size, shape and consistency of internal organs such as liver, pancreas, gallbladder, thyroid gland, ovaries, testes, uterus and other; it helps to determine structures and abnormalities of joints, muscles, tendons. Ultrasound test is routinely held during pregnancy for monitoring the growth of unborn child. Doppler ultrasound scans are used to listen to the heartbeat of fetus and to visualize the blood flow in arteries or veins of extremities (upper or lower) for diagnosing if patient might have deep vein thrombosis, peripheral arterial disease, injury of blood vessels following trauma.

Duplex ultrasound combines traditional ultrasound with Doppler ultrasound.

If patient needs internal biopsy, a procedure in which a sample of tissue is taken, the biopsy needle can be guided to the right place by ultrasound scan.

In some situations, a clearer picture can be obtained from an ultrasound transducer that is within the body: swallowed into the esophagus, placed in the vagina or rectum.

Ultrasound scans are painless and safe. They have not been found to cause any problems or complications.

Computed tomography

A CT scan is a sophisticated X-ray test, which produces multiple images of the inside of the body. It can give quite detailed picture of body's soft tissues, internal organs, blood vessels, brain and bones. 

The cross-sectional images generated during a CT scan can be reformatted in multiple planes, and can even generate three-dimensional images. These images can be viewed on a computer monitor, printed on film or transferred to a CD or DVD.

Using specialized equipment and expertise to create and interpret CT scans of the body, radiologist can more easily diagnose problems such as cardiovascular, inflammatory, infectious disease, musculoskeletal disorders, internal bleeding, trauma, cancer and etc.

In addition, CT examination is used to:

• Guide biopsies and other interventional procedures such as abscess drainages and minimally invasive tumor treatments;
• Plan for and assess the results of surgery, such as organ transplants or gastric bypass;
• Stage, plan and properly administer radiation treatments for tumors as well as monitor response to chemotherapy;
• Measure bone mineral density for the detection of osteoporosis;

CT scanning is fast, painless, noninvasive and accurate. It's is cheaper and less sensitive to patient movement than MRI.

Some risk you should take into consideration:

• During CT scan you get small amount of radiation, so it is not recommended for pregnant woman;
• Because children are more sensitive to radiation, they should have a CT exam only if it is essential for making a diagnosis and should not have repeated CT exams unless absolutely necessary;
• If you need to get intravenous contrast during the CT scan it isabsolutelynecessary to check renal function;

Magnetic-resonance imaging

An MRI scan is a painless and safe imaging method, which uses a strong magnetic field and radio waves to create picture soft body's soft tissues, internal organs, blood vessels, brain and joints. It may be safely used for fetal diagnostic;

Unlike CT scan that takes approximately couple minutes, MRI scan can take 20-45 minutes during which you need to lay motionlessly. Another embarrassment with MRI scans compared with CT scans is relative noise.

An MRI scan can create clear pictures of most parts of the body. So, it is useful for all sorts of reasons where other tests (such as X-rays) do not give enough information required.

As the MRI scanner uses an extremely strong magnet people with certain types of medical implant cannot be scanned. This is because the magnet can potentially move medical devices with metal in them, or affect their function.

Before the scan you have to fill in a safety questionnaire.

Because of the strong magnetic field pregnant women should not have this exam in the first three to four months of pregnancy unless the potential benefit from the MRI exam is assumed to outweigh the potential risks.

If you have claustrophobia (fear of enclosed spaces) or anxiety, you may want to ask your physician for a prescription for a mild sedative prior to your scheduled examination.

Infants and young children usually require sedation or anesthesia to complete an MRI exam without moving. Whether a child requires sedation depends on the child's age, intellectual development and the type of exam. Moderate and conscious sedation can be provided at many facilities. A physician or nurse specializing in sedation or anesthesia for children will be available during the exam for your child's safety.

In most cases, an MRI exam is safe for patients with metal implants, except for a few types. People with the following implants cannot be scanned and should not enter the MRI scanning area:

• Cochlear (ear) implant;
• Some types of clips used for brain aneurysms;
• Some types of metal coils placed within blood vessels;
• Nearly all cardiac defibrillators and pacemakers;
• Implanted medicine infusion ports;