Mesothelioma Diagnosis / Test – Magnetic Resonance Imaging (MRI) Scan

5 months ago

Mesothelioma is not always an easy disease to diagnosis, especially if the patient is unclear about his or her past exposure to asbestos.

An x-ray is almost always the first step towards making the diagnosis, but an x-ray – the least sophisticated form of diagnostic imaging available – is often not precise enough to make a definitive determination

Mesothelioma Diagnosis - MRI Scan

What Is an MRI ( Magnetic Resonance Imaging )?

Magnetic Resonance Imaging, originally known as Nuclear Magnetic Resonance Imaging, is a medical imaging technique that provides very detailed images of any part of the body.

By use of a powerful magnetic field, the MRI clearly shows the contrast of different soft tissues in the body. By changing exam parameters, the MRI can cause these tissues to take on different appearances. When this occurs, the radiologist who is observing the MRI can simply tell whether something inside the body is abnormal by the way it appears on the screen.

Unlike other diagnostic procedures, the MRI does not rely on radiation, making it an even safer procedure than most. Instead, when the body is inside the machine, radio waves redirect the axes of spinning protons, which are the nuclei of hydrogen atoms, in a strong magnetic field. This field is produced by allowing an electrical current to pass through wire coils inside the machine. Other coils that encircle the body send and receive radio waves, producing signals that are received by a computer. The signals generate images that each show a thin "slice" of the body. These images are then interpreted by a radiologist experienced in reading MRI results.

The MRI is even more accurate than the CT scan and provides extremely clear pictures. The test is especially accurate for detecting tumors in or around the lungs, and is thus often used for diagnosing mesothelioma. The MRI is particularly superior to a CT scan in discerning a tumor’s invasion through the diaphragm (the muscle below the lung cage that enables breathing) or through the mediastinum (the region in the chest between the lungs and behind the breast bone where the heart, major blood vessels, nerve tissue, and lymph glands are congregated).

MRI scans operate with radio waves and strong magnets rather than x-rays. The energy from the radio waves is absorbed by the body and then released in a pattern that varies depending on the type of tissue or disease being studied. The pattern of radio waves given off by the tissues is translated by a computer into a very detailed image of the scanned portion of the body. The MRI not only produces cross sectional slices of the body the way a CT scanner does, it also generates slices that run parallel to the length of the body.

How MRI ( Magnetic Resonance Imaging ) works ?

MRI (Magnetic Resonance Imaging ) Scan

The body is largely composed of water molecules which each contain two hydrogen nuclei or protons. When a person goes inside the powerful magnetic field of the scanner, the magnetic moments of these protons align with the direction of the field.

A radio frequency electromagnetic field is then briefly turned on, causing the protons to alter their alignment relative to the field. When this field is turned off the protons return to the original magnetization alignment. These alignment changes create a signal which can be detected by the scanner. The frequency at which the protons resonate depends on the strength of the magnetic field. The position of protons in the body can be determined by applying additional magnetic fields during the scan which allows an image of the body to be built up. These are created by turning gradient coils on and off which creates the knocking sounds heard during an MRI scan.

Diseased tissue, such as tumors, can be detected because the protons in different tissues return to their equilibrium state at different rates. By changing the parameters on the scanner this effect is used to create contrast between different types of body tissue.

Contrast agents may be injected intravenously to enhance the appearance of blood vessels, tumors or inflammation. Contrast agents may also be directly injected into a joint in the case of arthrograms, MRI images of joints. Unlike CT, MRI uses no ionizing radiation and is generally a very safe procedure. Patients with some metal implants, cochlear implants, and cardiac pacemakers are prevented from having an MRI scan due to effects of the strong magnetic field and powerful radio frequency pulses.

MRI is used to image every part of the body, and is particularly useful for neurological conditions, for disorders of the muscles and joints, for evaluating tumors, and for showing abnormalities in the heart and blood vessels.

Still, MRI scans tend to be a little more uncomfortable than CT scans. For the MRI, the patient lies absolutely still on a table that moves into the tube-shaped MRI machine, which directs radio waves towards the body. The patient will hear loud clicking and other noises during the procedure, but these sounds are harmless and are no indication of a problem. Most facilities will offer earplugs to block out the noise and many will provide headphones with music to mask the noise. The procedure lasts longer than a CT scan — usually from 30 to 90 minutes. If the patient has a fear of closed-in spaces, some facilities may offer a sedative before the test. All that said, many patients become so relaxed that they actually fall asleep during the test.

What are the benefit using MRI Scan ?

There are many benefits to undergoing MRI in the diagnosis of mesothelioma and other diseases. First of all, it does not expose patients to radiation as do other diagnostic procedures and the contrast dye used in MRIs is much safer than that used for CT scans. Furthermore, it is the most likely of all imaging tests to identify abnormalities and focal lesions on soft-tissue structures of the body, including the heart, liver, and other organs.

Risks are relatively few and are rarely reported. The only real risk, which is slight, could be an adverse reaction to the contrast dye that is sometimes used during the MRI procedure.

Source: Asbestos.com