Monday, August 17, 2020

MRI Scan


Hi friends!!!


In our previous blog, we have discussed about audiometer and types of audiometric tests. Please check out for the link given below.


Audiometer


In today's blog we are going to discuss about MRI scan.


The introduction of Magnetic Resonance Imaging (MRI) scan has created a revolution in the field of diagnostic radiology. MRI is an important equipment to view soft tissues inside the body.  Therefore it is important for every healthcare professionals to know about Magnetic Resonance Imaging (MRI) scan. 


Let's get into the topic. 


WHAT IS MRI SCAN?


The Magnetic resonance imaging (MRI) scan uses a strong magnetic fields and radio waves to produce detailed cross sectional images of organs and soft tissues inside the body. MRI scanning is a non invasive and painless procedure. MRI scans does not use ionizing radiation like CT scans and X rays.


During MRI scan, the scanner produces loud noise due to electric current in the scanner coils turning on and off. Because of this, during MRI scan patients will be instructed to use earplugs or ear phone to prevent the hearing damage.


Typical MRI scan takes between 15-20 minutes. In some cases it may extend up to 1 hour based on the area of scanning and number of images required.



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HOW MRI SCAN WORKS?


MRI scan works based on the principle of alignment and realignment of protons in the hydrogen molecule due to magnetic fields. Most part of our human body is made up of water molecules. The water molecules consists of hydrogen and oxygen atoms.


MRI scan consists of powerful magnets which produces strong magnetic field. The magnetic field makes protons in the hydrogen molecule to align with the same direction of magnetic field. Then the radio frequency waves are passed on to the specific region of interest in the patient’s body.


These burst of radio waves disturbs the alignment of protons. When radio waves are turned off, these protons are again realigned to the direction of magnetic field. These realignment of protons produces radio signals, which are then received by the receivers.


The protons in different parts of body realign at different speeds and emits different levels of radio signals. The time it takes for the protons to realign and level of energy released depends on the environment and chemical mature of the proton molecule.


Contrast agents may be given to the patients before and during the MRI scan procedure to increase the speed of proton realignment. Faster the process of realignment, better will be the image quality.


Based on this, the MRI scan algorithm distinguishes the different tissues of the body and provide information on the location of the proton molecule. This is how MRI scan works.


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WHAT IS THE PREPARATION

BEFORE MRI SCAN?


During MRI scan patient’s will be asked to remove metals objects from the body such as jewellery, watches etc. Patient’s having implants like pacemakers, cochlear implant, artificial bone joint, artificial heart valves, vascular stents will not be allowed to undergo MRI scan.


Patient’s are provided with earphones to prevent hearing damage due to loud noise created during MRI scan procedure.


Sometimes, contrast agents will be given to improve the visibility of tissues.


DURING MRI SCAN


During MRI scan patient’s will be asked to remain still without any movement. Sometimes based on the requirement of area being imaged, patients are requested to hold their breath.


The technician and patients can communicate via two way intercom connection during MRI scan. The patient’s are provided with an alarm button to alert the technicians in case of discomfort.


AFTER MRI SCAN


If IV Catheter is used for contrast injection, it is removed after the MRI scan procedure. And patient’s will be given instructions to observe any allergic reaction due to contrast usage.


If sedation was given, patients are asked to wait for sometime until they gain their consciousness.


Image courtesy: wikimedia commons
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Now I hope you have acquired some knowledge about MRI scan and how MRI scan works. We will discuss in detail about MRI scan of various body parts and MRI scan with and without contrast in our next blog.


NOTE: Dear friends!!! ...Please do comment a topic related to Biomedical, so that we can discuss it in future blogs.


Check out for this blog about Computed Tomography and x ray.

Generations of CT Scanners

COMPUTED TOMOGRAPHY|TECHNOLOGY|ARTIFACTS

x ray machine working principle

components of x ray tube


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