Imagine this: you’re at the doctor and they just can’t seem to identify what is causing you pain. They know that something is wrong, but they just can’t see it from the outside. In this situation, a doctor might recommend an MRI, or a Magnetic Resonance Image. But how does this all-seeing machine (that can help to identify brain tumors, vascular anomalies, eye disorders, and pituitary gland diseases) really operate?
A woman prepares for an MR by situating herself on the patient table.
As shown in the diagram below, an MRI is an extremely large cylindrical tube, enclosed by a circular magnet. This superconducting magnet consists of many coils (winding of wire) through which an electric current is passed. Resistive, grandiant, and permanent magnets are all components of the MRI as well, but are each used to a lesser extent. Those who receive an MRI lie on an examination table that slides in and out of the machine and the center of the magnet.
The doctor will position the patient so that the body part they want to examine is in the isocenter of the magnetic field. As we learned in class, a current carrying wire creates the magnetic field (B). If the wire was visible, we could use the first right hand rule to find the magnetic field by pointing our right thumb in the direction of the current and then wrapping our fingers to find the direction of the magnetic field. They may inject the patient with a contrast (or dyes) to alter the local magnetic field in the area being examined.The MRI machine uses a magnatic field and radio waves to create a 3-D image of the body, the likes of which could not be duplicated using an X-Ray or a CT Scan.
The MRI above shows a foot that has been infected, and was later treated thanks to the images provided by MRI technology.
This magnetic field comes from an electic current that passes throuh the wire loops. During this process, coils in the magnet send and receive radio waves. In result, protons in the body begin to align themselves. Once these protons have been aligned, they absorb radio waves which spin (or precess) instantly. They then emit energy signals that are read by the coil. This information is sent to a computer, which generates these signals into a 3-D image that represents the area being examined.To see this process in action, watch the video below!
20 to 90 minutes later, the MRI will have commenced. But we wary though, you may be a little stiff. Afterall, even the slightest movement of the area being scanned can distort the MRI images. Yet the high cost and amount of time is well worth it; MRI’s provide a picture of your insides incomparable to that of any other machine.
Imagine this: you’re at the doctor and they just can’t seem to identify what is causing you pain. They know that something is wrong, but they just can’t see it from the outside. In this situation, a doctor might recommend an MRI, or a Magnetic Resonance Image. But how does this all-seeing machine (that can help to identify brain tumors, vascular anomalies, eye disorders, and pituitary gland diseases) really operate?
As shown in the diagram below, an MRI is an extremely large cylindrical tube, enclosed by a circular magnet. This superconducting magnet consists of many coils (winding of wire) through which an electric current is passed. Resistive, grandiant, and permanent magnets are all components of the MRI as well, but are each used to a lesser extent. Those who receive an MRI lie on an examination table that slides in and out of the machine and the center of the magnet.
The doctor will position the patient so that the body part they want to examine is in the isocenter of the magnetic field. As we learned in class, a current carrying wire creates the magnetic field (B). If the wire was visible, we could use the first right hand rule to find the magnetic field by pointing our right thumb in the direction of the current and then wrapping our fingers to find the direction of the magnetic field. They may inject the patient with a contrast (or dyes) to alter the local magnetic field in the area being examined.The MRI machine uses a magnatic field and radio waves to create a 3-D image of the body, the likes of which could not be duplicated using an X-Ray or a CT Scan.
This magnetic field comes from an electic current that passes throuh the wire loops. During this process, coils in the magnet send and receive radio waves. In result, protons in the body begin to align themselves. Once these protons have been aligned, they absorb radio waves which spin (or precess) instantly. They then emit energy signals that are read by the coil. This information is sent to a computer, which generates these signals into a 3-D image that represents the area being examined.To see this process in action, watch the video below!
20 to 90 minutes later, the MRI will have commenced. But we wary though, you may be a little stiff. Afterall, even the slightest movement of the area being scanned can distort the MRI images. Yet the high cost and amount of time is well worth it; MRI’s provide a picture of your insides incomparable to that of any other machine.
Works Cited:
http://www.radiologyinfo.org/en/info.cfm?pg=headmr
http://www.medicalnewstoday.com/articles/146309.php
http://science.howstuffworks.com/mri5.htm