MRI stands for Magnetic resonance imaging that is a radiological imaging technology which creates images of the body’s anatomy and physiological processes. Strong magnetic fields, magnetic field gradients and radio waves are used in MRI scanners to create images of the body’s organs. MRI scans do not employ X-rays or ionizing radiation, which sets them apart from CT and PET scans. MRI is a type of nuclear magnetic resonance (NMR) imaging technique that can also be employed in other NMR applications, such as NMR spectroscopy.
What is magnetic resonance imaging?
Magnetic Resonance Imaging (MRI) is a non-invasive imaging technique that creates comprehensive three-dimensional anatomy images. It’s frequently used to detect diseases, diagnose them and track their progress. It is based on cutting-edge technology that excites and detects changes in the rotational axis of protons in the water that makes up biological tissues.
An MRI scan creates a detailed cross-sectional image of interior organs and structures using a powerful magnet, radio waves and a computer. The scanner is usually shaped like a long tube with a table in the middle into which the patient can slide.
An MRI scan varies from CT scans as X-rays are used in CT scans but MRI scans do not use any ionizing radiation, which can be dangerous. MRI scanners are especially well adapted to image the non-bony portions of the body, such as soft tissues. They differ from computed tomography as they do not employ x-rays, which are harmful ionizing radiation. MRI images the brain, spinal cord, and nerves, as well as muscles, ligaments, and tendons, considerably more clearly than normal x-rays and CT.As a result, MRI is frequently used to image knee and shoulder problems.
MRI can distinguish between white and grey matter in the brain and can also be used to diagnose aneurysms and malignancies. MRI is the imaging modality of choice when frequent imaging is necessary for diagnosis or therapy, especially in the brain, because it does not use x-rays or other forms of radiation. But MRI is more costly than x-ray imaging or CT scanning. Functional Magnetic Resonance Imaging is one type of specialized MRI (fMRI.) This is used to look at brain structures and see which parts of the brain activate during different cognitive tasks.
What is MRI working principle?
Because of the unique make-up of the human body, MRI scanners are utilized as an imaging approach. Our bodies are completely made up of cells, each of which contains water. MRI produces detailed images from any part of the body by utilizing the body’s own magnetic properties. Because hydrogen nucleus is abundant in water and fat, it is employed for imaging. The hydrogen proton is analogous to the earth, which spins on its axis and has a north-south pole. In this way, it’s similar to a little bar magnet. These hydrogen proton bar magnets rotate in the body with their axes randomly aligned under normal circumstances.
The protons’ axes all line up when the body is placed in a high magnetic field, such as an MRI scanner. The magnetic vector created by this consistent alignment is aligned along the MRI scanner’s axis. MRI scanners come in different field strengths, usually between 0.5 and 1.5 tesla.
The magnetic vector is deflected when more energy is provided to the magnetic field in the form of radio waves. The element required (hydrogen in this case) and the strength of the magnetic field determine the radio wave frequency (RF) that causes the hydrogen nuclei to resonate. Using a series of gradient electric coils, the strength of the magnetic field may be changed electronically from head to toe, and by changing the local magnetic field in small increments, different slices of the body will resonate as different frequencies are applied.
When the radiofrequency source is turned off, the magnetic vector returns to its resting condition, which results in the emission of a signal (a radio wave). This signal is utilized to generate magnetic resonance images. The protons will gradually revert to their original state when the magnet is turned off by a process known as precession. Fundamentally, different tissue types within the body return at different speeds, and this is the moment at which the body’s many tissues may be visualized and distinguished. Receiver coils are placed around the bodily component in issue to act as aerials, allowing the transmitted signal to be detected more easily. The received signal’s intensity is then plotted on a grey scale, and cross sectional images are created.
MRI uses powerful magnets to create a strong magnetic field that compels protons in the body to align with it. The protons are activated and spin out of equilibrium, straining against the magnetic field’s pull, when a radiofrequency current is pulsed through the patient. The MRI sensors can detect the energy produced as the protons realign with the magnetic field when the radiofrequency field is switched off. The quantity of energy released and the time it takes for the protons to realign with the magnetic field vary, depending on the environment and the chemical makeup of the molecules. Physicians are able to tell the difference between various types of tissues based on these magnetic properties.
A patient is placed inside a huge magnet to obtain an MRI scan and must remain stationary during the imaging process to avoid blurring the image. To accelerate the speed at which protons realign with the magnetic field, contrast medications may be given intravenously to a patient before or during the MRI. The brighter the image, the faster the protons realign.
What is CT scan?
A computerized tomography scan (CT or CAT scan) creates cross-sectional images of the body using computers and rotating X-ray devices. These images contain more information than standard X-ray images. Soft tissues, blood veins, and bones in various regions of the body can be seen. The head, shoulders, spine, heart, belly, knee, and chest can all be visualized with a CT scan.
A CT scan requires lying down in a tunnel-like machine while the inside spins and takes a succession of X-rays from various angles. These photographs are then transferred to a computer, where they are merged to create images of body slices. They may also be combined to produce a 3-D image of a particular area of the body.
CT scan working principle
A CT scan involves the patient lying on a bed that moves slowly through the gantry as an x-ray tube rotates around them, blasting narrow beams of x-rays through the body. CT scanners use digital x-ray detectors instead of film, which are placed directly opposite the x-ray source. The detectors take up the x-rays as they leave the patient and send them to a computer.
As it moves through an arc, a CT scanner emits a series of narrow beams into the human body. An X-ray machine, on the other hand, sends only one radiation beam. Compared to an X-ray image, a CT scan produces a more detailed final image. The X-ray detector in a CT scanner can detect hundreds of different degrees of density. It has the ability to view tissues within a solid organ. This information is sent to a computer, which creates a 3-D cross-sectional image of the bodily component and presents it on the screen.
MRI vs CT scan
Despite the fact that the risks of ionizing radiation are now effectively regulated in most medical settings, an MRI may still be preferred over a CT scan. Without exposing the body to radiation, MRI is frequently used in hospitals and clinics for medical diagnosis, staging, and follow-up of disease. When compared to a CT scan, an MRI may provide different information. MRI scans may be associated with risks and discomfort. MRI scans take longer and are noisier than CT scans and they frequently require the participant to enter a tight and confining tube. Here are some points that will clear that is MRI better or CT scan.
- Usually MRI machines take a lot of time, however CT scans are faster. MRI is used when there is no emergency case to get detailed soft tissues look.
- MRI is much expensive than CT scan.
- CT scan can give you only brief information that is just used to diagnose the soft tissue problems but MRI can provide complete information about the fracture part of body.
- CT scans are quieter and more comfortable than MRI scans.
- CT scans expose patient to radiation while MRI doesn’t.
However, both are safe almost. The basic purpose of both techniques is to get the anatomy’s pictures for diagnosing diseases or other problems.