What are Medical Imaging Techniques (X Rays, CT Scan, MRI Scan and Ultra Sound Scanning) ??

Why do Physicians require Medical Imaging Techniques?

Physicians many a times cannot diagnose the diseases simply by the history and clinical symptoms. It is necessary for them to go further to study the condition of the internal organs and investigate them to accurately diagnose the disease. This is also needed to carry surgical procedures on the organ.

The organs can be studied by means of imaging. The images of the organ to be studied will be made on a photographic film or on the computer screen to facilitate a detailed study and to pin point the cause of the disease.

There are several methods if imaging techniques by which the organs can be studied.

Selection of the technique depends on the type of organ to be investigated.

They are:

1. Plain ‘X’ rays.
2. Contrast ‘X’ Rays.
3. C.T. Scan. ( Computer Assisted Tomography)
4. MRI ( Magnetic Resonance Imaging)
5. Ultra sound scanning.

1. Plain ‘X’ Rays:

This is the basic investigative procedure very use full to study the condition of bones and some soft tissues like breasts. It is the most non invasive procedure and can be completed in 10-15 minutes. This is carried out by a radiologist using ‘X’ rays. These are also known as Roentgen rays with a small wave length with high energy. The ‘X’ rays can penetrate all soft tissues in the body and cannot pass through the hard tissues like bone, tumors etc.

Therefore they create images on the photographic film when they are passed through the body. The hard structures like bones appear white on the film and softer tissues appear black or grey depending on their transmission level. For taking an ‘X’ ray photograph the patient will be asked to lie down on a table and the film will be placed just below the part to be investigated. ‘X’ rays are beamed for a fraction of a second and the image is obtained on the film.

2.Contrast ‘X’ rays:

Plain ‘X’ Rays cannot take images of soft tissues like blood vessels and intestines. To study these organs a contrast substance is introduced into them so that they are visible. The ‘X’ rays are absorbed by the contrast media making the part appearing as white. The contrast media varies with the organ to be studied. These contrast ‘X’ Rays are used to study the condition of the blood vessels, intestines and urinary system.

Blood vessels:

To study the blood vessels a catheter is passed through the blood vessel and pushed to the site of study till the tip of the catheter reaches the point where the dye is pushed. With the help of the dye the blood vessels are clearly seen as white on the photographic film or on the computer screen. Angiography is done similarly to study the blockages in the coronary blood vessels.

Gastro Intestinal System:

Contrast ‘X-rays are also used to study upper gastro intestinal tract and the colon. Barium sulphate is used as a contrast media to study. Barium sulphate is a chalky liquid does not absorb from the intestines and as such when ‘X’ Rays are beamed through the gastrointestinal tract they appear white clearly. Now a day more sophisticated methods like endoscopy is replacing this technique.

Urinary System:

Contrast ‘X’ Rays are also used for studying problems in the urinary system also. When a dye is injected into the blood stream it gets concentrated in the kidneys first and latter excreted out through urine. Therefore the urinary system can be studied. The dye can also be injected into the bladder directly by a urinary catheter and the bladder can be studied. However latest methods like endoscopy, cystoscopy are replacing this method.

3. CT.Scan (Computer assisted tomography):

It is a modern imaging system and the images are sent to the computer where they are analyzed in detail. That means in this system a computer and ‘X’ Rays are used in conjunction to study in a detailed manner. An ‘X’ Ray tube and an ‘x’ ray detector is used simultaneously in opposite angles and they rotate around the part under study and take several images and forward them into the computer. The data can be stored or printed on a photographic film.

The images obtained are very clear enabling to study the problems accurately. CT scans are used to study the problems in the brain like cancer, tumors, and blocks causing strokes, spinal cord, Chest, abdomen or pelvis. When compared to other methods CT scans are more expensive and are not available in small towns and in villages.

4.MRI (Magnetic Resonance Imaging):

It is another sophisticated medical imaging technology in which the images are more clear and in a detailed manner. Magnetic radio waves are used instead of ‘X’ Rays. Therefore it is a safe system.

The data is analyzed by the computer. Although the CT scans and MRI are similar, MRI images are clearer and tissues like tumors and cancers are clearly visible. Though highly expensive it is more sophisticated and very accurate and safest method.

5.Ultra Sound Scanning:

As the name itself implies sound waves are used in this process to make the images. High frequency sound waves not audible to human ears are used instead radiation waves. Therefore this is also a safe method even for pregnant women. The waves can pass through the deeper tissues and can create pictures. The instrument creates the sound waves is called a Transducer. When it is pressed on the skin the sound waves are produced and pass the tissues underneath. The waves while passing when obstructed by tissues and get reflected. The reflected waves are again received by the transducer and fed to the computer.

The computer analyzes the data. The transducers are available in different models suitable either for external or internal use. Internal transducers are used to study the female reproductive organs like uterus, ovaries and fallopian tubes. In males commonly used to study the prostate gland. The images can be seen on the computer screen. It can also be used to study the movement of the fetus and abnormalities. By moving the transducer the image can be seen continuously. Almost all the internal organs can be studied with this method. It is not an expensive like CT scan or MRI and available even in rural areas and in small towns.