Magnetic resonance imaging (MRI), also known as nuclear magnetic resonance imaging, is a technique for creating detailed images of the human body.
Working of an MRI Scan
The technique uses a very powerful magnet to align the nuclei of atoms inside the body, and a variable magnetic field that causes the atoms to resonate, a phenomenon called nuclear magnetic resonance. The nuclei produce their own rotating magnetic fields that a scanner detects and uses to create an image.
Need for an MRI Scan
An MRI scan can be used as an extremely accurate method of disease detection throughout the body. They may be done to provide more information about a problem seen on an X-ray, ultrasound, or CT scan.
Types of MRI
Technically known as cardiovascular magnetic resonance (CMR), it operates on the same principles as that of an MRI, but customized for use in ‘matters of the heart.’ Anatomy of the heart, cardiomyopathies, pericardial diseases, coronary artery disease, thrombus and ventricular disorders can be easily diagnosed using this technique. The CMR will be carried out in a fashion similar to the conventional MRI, but you may have to hold your breath for short periods of time when image will be recorded.
It has many advantages such as a clear image quality, accuracy, low-energy radiation and safety. Most importantly, it can be easily correlated with an ECG at the same time
Magnetic Resonance Angiography (MRA)
Angiography in general is a medical test which s used to diagnose abnormalities in blood vessels of the body, most commonly the arteries of the brain, legs, neck, chest, abdomen, pelvis and arms. An angiogram can be obtained using fluoroscopy, computed tomography or an MRI scan
Magnetic Resonance Venography (MRV)
MRV checks the flow of blood in veins accurately. Strokes, aneurysms, vascular disease or any obstruction in veins can be detected using this method. A contrast media (a dye that makes your blood vessels look opaque in the scan) may or may not be injected into the veins.
Diffusion is defined as the movement of molecules from a region of high concentration to a lower one. This principle is used to determine the direction of nerve fibres in the brain, especially white matter. Combined with diffused tensor imaging (DTI), diffusion can be studied in multiple directions to create a brain map showing connectivity in different regions of the brain. Stroke can be easily detected using this method.
Magnetic Resonance Spectroscopy
Also known as nuclear magnetic resonance spectroscopy (NMR), this technique operates by detecting changes in metabolites produced in response to certain diseases, especially that of the nervous system and muscular system. Where an MRI scan creates a 2D image of the concerned area, an MRS will supplement information using 1H signals to compare the chemical compositions of normal tissue versus abnormal tissues (tumors, stroke, epilepsy, etc.)