How MRI Scans Work

VISUALISATION IN MEDICINE HOW MRI SCANS WORK Invented by Raymond Damadian - United States in1977 MRI Scan uses Magnetic Resonance Imaging (MRI) is an imaging technique used in medical settings to produce high quality images of the inside of the human body, like detailed pictures of organs, soft tissue, bone and virtually all internal body structures. MRI Scanner Patient Motorised Table Computer A Step by Step Guide The Inner Workings Radio Frequency Transmitter & Receiver Hydrogen Protons Sends and receives radio signals Water makes up 60-70% of the human body Water = molecules of Hydrogen and Oxygen atoms (H,O) The protons in Hydrogen atoms naturally spin on a variety of axes Main Magnetic Coil Creates a uniform magnetic field The Main Magnetic Coil X Magnetic Coils Create a varying magnetic field from left to right • The main magnetic coil creates a uniform magnetic field around the patient • The spinning Hydrogen protons in the patient's body will align with the magnetic field Y Magnetic Coils Create a varying magnetic field from O to bottom Z Magnetic Coils The Radio Signal Transmitter Create a varying magnetic field from head to toe The radio transmitter sends out radio wave pulses of varying frequencies When the frequency of the radio wave matches the frequency at which the proton is spinning, the proton absorbs the energy of the radio wave The additional energy causes the proton to tilt out of alignment with the magnetic field Output Uses The Radio Signal Receiver Differences in tissue type are shown Used to detect: as differences in colour contrast • When the pulse of the radio wave ends, the proton returns to alignment with the magnetic field, and emits a (resonant) signal of the same frequency as the radio signal it absorbed The resonant signal is picked up by the radio receiver The computer maps the location data and tissue type data to produce an image of the body Haemorrhages • Tumours Cysts Brain Infections Torn Ligaments And other Pathologies The X,Y and Z Magnetic Coils The resonant frequency of the atom depends on the type of atom (i.e. Hydrogen), the surrounding atoms (i.e. the type of tissue), and the strength of the magnetic field The X,Y and Z magnetic coils create a second magnetic field of varying intensity on top of the static magnetic field Because resonant frequency is proportional to the strength of the field, protons in different locations will then have different resonant frequencies The level of detail from an MRI scan is far higher than a CT scan or X-ray. Because radio waves have much less energy than X-rays, they are a non-iodising form of radiation, which makes an MRI much safer than X-rays and CT scans. 6. The Computer MRI stands for Magnetic Resonance Imaging, and uses information contained within the resonant signals to create an image of the patient's body The computer matches incoming resonant frequencies to the location of the individual protons Hydrogen protons in different kinds of tissue emit response signals of a different length, e.g. the response signal from bone is different from blood, which is different from the heart etc. Associated Risks There is no evidence that the magnetic waves used in MRI scans pose any health risks. However, accidents have previously occurred where unsecured metal objects in the scanning room have been drawn to the magnetic field of the MRI scanner and caused projectile injury. Strict protocols are in place by most health organisations to ensure this doesn't happen. Cancerous tissue emits a signal of greater length than non-cancerous tissue The computer matches the length of the signal to tissue type Sources http://www.cis.rit.edu/htbooks/mri/inside.htm http://web.mit.edu/invent/a-winners/a-damadian.html http://www.beyonddiscovery.org/content/view.article.asp?a=129 http://invigorate.royalsociety.org/ks4/a-window-on-the-brain/the-science-behind-the-scenes.aspx http://dev.ersnet.org/uploads/Document/8d/WEB_CHEMIN_2563_ I194523150.pdf http://www.nlm.nih.gov/medlineplus/ency/article/003335.htm http://commons.wikimedia.org/wiki/File:MRI_head_side.jpg Graphic Created by Acclarent UK http://www.balloonsinuplasty.co.uk/about-acclarent/ Original URL http://www.balloonsinuplasty.co.uk/visualisation-in-medicine/ VISUALISATION IN MEDICINE HOW MRI SCANS WORK Invented by Raymond Damadian - United States in1977 MRI Scan uses Magnetic Resonance Imaging (MRI) is an imaging technique used in medical settings to produce high quality images of the inside of the human body, like detailed pictures of organs, soft tissue, bone and virtually all internal body structures. MRI Scanner Patient Motorised Table Computer A Step by Step Guide The Inner Workings Radio Frequency Transmitter & Receiver Hydrogen Protons Sends and receives radio signals Water makes up 60-70% of the human body Water = molecules of Hydrogen and Oxygen atoms (H,O) The protons in Hydrogen atoms naturally spin on a variety of axes Main Magnetic Coil Creates a uniform magnetic field The Main Magnetic Coil X Magnetic Coils Create a varying magnetic field from left to right • The main magnetic coil creates a uniform magnetic field around the patient • The spinning Hydrogen protons in the patient's body will align with the magnetic field Y Magnetic Coils Create a varying magnetic field from O to bottom Z Magnetic Coils The Radio Signal Transmitter Create a varying magnetic field from head to toe The radio transmitter sends out radio wave pulses of varying frequencies When the frequency of the radio wave matches the frequency at which the proton is spinning, the proton absorbs the energy of the radio wave The additional energy causes the proton to tilt out of alignment with the magnetic field Output Uses The Radio Signal Receiver Differences in tissue type are shown Used to detect: as differences in colour contrast • When the pulse of the radio wave ends, the proton returns to alignment with the magnetic field, and emits a (resonant) signal of the same frequency as the radio signal it absorbed The resonant signal is picked up by the radio receiver The computer maps the location data and tissue type data to produce an image of the body Haemorrhages • Tumours Cysts Brain Infections Torn Ligaments And other Pathologies The X,Y and Z Magnetic Coils The resonant frequency of the atom depends on the type of atom (i.e. Hydrogen), the surrounding atoms (i.e. the type of tissue), and the strength of the magnetic field The X,Y and Z magnetic coils create a second magnetic field of varying intensity on top of the static magnetic field Because resonant frequency is proportional to the strength of the field, protons in different locations will then have different resonant frequencies The level of detail from an MRI scan is far higher than a CT scan or X-ray. Because radio waves have much less energy than X-rays, they are a non-iodising form of radiation, which makes an MRI much safer than X-rays and CT scans. 6. The Computer MRI stands for Magnetic Resonance Imaging, and uses information contained within the resonant signals to create an image of the patient's body The computer matches incoming resonant frequencies to the location of the individual protons Hydrogen protons in different kinds of tissue emit response signals of a different length, e.g. the response signal from bone is different from blood, which is different from the heart etc. Associated Risks There is no evidence that the magnetic waves used in MRI scans pose any health risks. However, accidents have previously occurred where unsecured metal objects in the scanning room have been drawn to the magnetic field of the MRI scanner and caused projectile injury. Strict protocols are in place by most health organisations to ensure this doesn't happen. Cancerous tissue emits a signal of greater length than non-cancerous tissue The computer matches the length of the signal to tissue type Sources http://www.cis.rit.edu/htbooks/mri/inside.htm http://web.mit.edu/invent/a-winners/a-damadian.html http://www.beyonddiscovery.org/content/view.article.asp?a=129 http://invigorate.royalsociety.org/ks4/a-window-on-the-brain/the-science-behind-the-scenes.aspx http://dev.ersnet.org/uploads/Document/8d/WEB_CHEMIN_2563_ I194523150.pdf http://www.nlm.nih.gov/medlineplus/ency/article/003335.htm http://commons.wikimedia.org/wiki/File:MRI_head_side.jpg Graphic Created by Acclarent UK http://www.balloonsinuplasty.co.uk/about-acclarent/ Original URL http://www.balloonsinuplasty.co.uk/visualisation-in-medicine/ VISUALISATION IN MEDICINE HOW MRI SCANS WORK Invented by Raymond Damadian - United States in1977 MRI Scan uses Magnetic Resonance Imaging (MRI) is an imaging technique used in medical settings to produce high quality images of the inside of the human body, like detailed pictures of organs, soft tissue, bone and virtually all internal body structures. MRI Scanner Patient Motorised Table Computer A Step by Step Guide The Inner Workings Radio Frequency Transmitter & Receiver Hydrogen Protons Sends and receives radio signals Water makes up 60-70% of the human body Water = molecules of Hydrogen and Oxygen atoms (H,O) The protons in Hydrogen atoms naturally spin on a variety of axes Main Magnetic Coil Creates a uniform magnetic field The Main Magnetic Coil X Magnetic Coils Create a varying magnetic field from left to right • The main magnetic coil creates a uniform magnetic field around the patient • The spinning Hydrogen protons in the patient's body will align with the magnetic field Y Magnetic Coils Create a varying magnetic field from O to bottom Z Magnetic Coils The Radio Signal Transmitter Create a varying magnetic field from head to toe The radio transmitter sends out radio wave pulses of varying frequencies When the frequency of the radio wave matches the frequency at which the proton is spinning, the proton absorbs the energy of the radio wave The additional energy causes the proton to tilt out of alignment with the magnetic field Output Uses The Radio Signal Receiver Differences in tissue type are shown Used to detect: as differences in colour contrast • When the pulse of the radio wave ends, the proton returns to alignment with the magnetic field, and emits a (resonant) signal of the same frequency as the radio signal it absorbed The resonant signal is picked up by the radio receiver The computer maps the location data and tissue type data to produce an image of the body Haemorrhages • Tumours Cysts Brain Infections Torn Ligaments And other Pathologies The X,Y and Z Magnetic Coils The resonant frequency of the atom depends on the type of atom (i.e. Hydrogen), the surrounding atoms (i.e. the type of tissue), and the strength of the magnetic field The X,Y and Z magnetic coils create a second magnetic field of varying intensity on top of the static magnetic field Because resonant frequency is proportional to the strength of the field, protons in different locations will then have different resonant frequencies The level of detail from an MRI scan is far higher than a CT scan or X-ray. Because radio waves have much less energy than X-rays, they are a non-iodising form of radiation, which makes an MRI much safer than X-rays and CT scans. 6. The Computer MRI stands for Magnetic Resonance Imaging, and uses information contained within the resonant signals to create an image of the patient's body The computer matches incoming resonant frequencies to the location of the individual protons Hydrogen protons in different kinds of tissue emit response signals of a different length, e.g. the response signal from bone is different from blood, which is different from the heart etc. Associated Risks There is no evidence that the magnetic waves used in MRI scans pose any health risks. However, accidents have previously occurred where unsecured metal objects in the scanning room have been drawn to the magnetic field of the MRI scanner and caused projectile injury. Strict protocols are in place by most health organisations to ensure this doesn't happen. Cancerous tissue emits a signal of greater length than non-cancerous tissue The computer matches the length of the signal to tissue type Sources http://www.cis.rit.edu/htbooks/mri/inside.htm http://web.mit.edu/invent/a-winners/a-damadian.html http://www.beyonddiscovery.org/content/view.article.asp?a=129 http://invigorate.royalsociety.org/ks4/a-window-on-the-brain/the-science-behind-the-scenes.aspx http://dev.ersnet.org/uploads/Document/8d/WEB_CHEMIN_2563_ I194523150.pdf http://www.nlm.nih.gov/medlineplus/ency/article/003335.htm http://commons.wikimedia.org/wiki/File:MRI_head_side.jpg Graphic Created by Acclarent UK http://www.balloonsinuplasty.co.uk/about-acclarent/ Original URL http://www.balloonsinuplasty.co.uk/visualisation-in-medicine/ VISUALISATION IN MEDICINE HOW MRI SCANS WORK Invented by Raymond Damadian - United States in1977 MRI Scan uses Magnetic Resonance Imaging (MRI) is an imaging technique used in medical settings to produce high quality images of the inside of the human body, like detailed pictures of organs, soft tissue, bone and virtually all internal body structures. MRI Scanner Patient Motorised Table Computer A Step by Step Guide The Inner Workings Radio Frequency Transmitter & Receiver Hydrogen Protons Sends and receives radio signals Water makes up 60-70% of the human body Water = molecules of Hydrogen and Oxygen atoms (H,O) The protons in Hydrogen atoms naturally spin on a variety of axes Main Magnetic Coil Creates a uniform magnetic field The Main Magnetic Coil X Magnetic Coils Create a varying magnetic field from left to right • The main magnetic coil creates a uniform magnetic field around the patient • The spinning Hydrogen protons in the patient's body will align with the magnetic field Y Magnetic Coils Create a varying magnetic field from O to bottom Z Magnetic Coils The Radio Signal Transmitter Create a varying magnetic field from head to toe The radio transmitter sends out radio wave pulses of varying frequencies When the frequency of the radio wave matches the frequency at which the proton is spinning, the proton absorbs the energy of the radio wave The additional energy causes the proton to tilt out of alignment with the magnetic field Output Uses The Radio Signal Receiver Differences in tissue type are shown Used to detect: as differences in colour contrast • When the pulse of the radio wave ends, the proton returns to alignment with the magnetic field, and emits a (resonant) signal of the same frequency as the radio signal it absorbed The resonant signal is picked up by the radio receiver The computer maps the location data and tissue type data to produce an image of the body Haemorrhages • Tumours Cysts Brain Infections Torn Ligaments And other Pathologies The X,Y and Z Magnetic Coils The resonant frequency of the atom depends on the type of atom (i.e. Hydrogen), the surrounding atoms (i.e. the type of tissue), and the strength of the magnetic field The X,Y and Z magnetic coils create a second magnetic field of varying intensity on top of the static magnetic field Because resonant frequency is proportional to the strength of the field, protons in different locations will then have different resonant frequencies The level of detail from an MRI scan is far higher than a CT scan or X-ray. Because radio waves have much less energy than X-rays, they are a non-iodising form of radiation, which makes an MRI much safer than X-rays and CT scans. 6. The Computer MRI stands for Magnetic Resonance Imaging, and uses information contained within the resonant signals to create an image of the patient's body The computer matches incoming resonant frequencies to the location of the individual protons Hydrogen protons in different kinds of tissue emit response signals of a different length, e.g. the response signal from bone is different from blood, which is different from the heart etc. Associated Risks There is no evidence that the magnetic waves used in MRI scans pose any health risks. However, accidents have previously occurred where unsecured metal objects in the scanning room have been drawn to the magnetic field of the MRI scanner and caused projectile injury. Strict protocols are in place by most health organisations to ensure this doesn't happen. Cancerous tissue emits a signal of greater length than non-cancerous tissue The computer matches the length of the signal to tissue type Sources http://www.cis.rit.edu/htbooks/mri/inside.htm http://web.mit.edu/invent/a-winners/a-damadian.html http://www.beyonddiscovery.org/content/view.article.asp?a=129 http://invigorate.royalsociety.org/ks4/a-window-on-the-brain/the-science-behind-the-scenes.aspx http://dev.ersnet.org/uploads/Document/8d/WEB_CHEMIN_2563_ I194523150.pdf http://www.nlm.nih.gov/medlineplus/ency/article/003335.htm http://commons.wikimedia.org/wiki/File:MRI_head_side.jpg Graphic Created by Acclarent UK http://www.balloonsinuplasty.co.uk/about-acclarent/ Original URL http://www.balloonsinuplasty.co.uk/visualisation-in-medicine/ VISUALISATION IN MEDICINE HOW MRI SCANS WORK Invented by Raymond Damadian - United States in1977 MRI Scan uses Magnetic Resonance Imaging (MRI) is an imaging technique used in medical settings to produce high quality images of the inside of the human body, like detailed pictures of organs, soft tissue, bone and virtually all internal body structures. MRI Scanner Patient Motorised Table Computer A Step by Step Guide The Inner Workings Radio Frequency Transmitter & Receiver Hydrogen Protons Sends and receives radio signals Water makes up 60-70% of the human body Water = molecules of Hydrogen and Oxygen atoms (H,O) The protons in Hydrogen atoms naturally spin on a variety of axes Main Magnetic Coil Creates a uniform magnetic field The Main Magnetic Coil X Magnetic Coils Create a varying magnetic field from left to right • The main magnetic coil creates a uniform magnetic field around the patient • The spinning Hydrogen protons in the patient's body will align with the magnetic field Y Magnetic Coils Create a varying magnetic field from O to bottom Z Magnetic Coils The Radio Signal Transmitter Create a varying magnetic field from head to toe The radio transmitter sends out radio wave pulses of varying frequencies When the frequency of the radio wave matches the frequency at which the proton is spinning, the proton absorbs the energy of the radio wave The additional energy causes the proton to tilt out of alignment with the magnetic field Output Uses The Radio Signal Receiver Differences in tissue type are shown Used to detect: as differences in colour contrast • When the pulse of the radio wave ends, the proton returns to alignment with the magnetic field, and emits a (resonant) signal of the same frequency as the radio signal it absorbed The resonant signal is picked up by the radio receiver The computer maps the location data and tissue type data to produce an image of the body Haemorrhages • Tumours Cysts Brain Infections Torn Ligaments And other Pathologies The X,Y and Z Magnetic Coils The resonant frequency of the atom depends on the type of atom (i.e. Hydrogen), the surrounding atoms (i.e. the type of tissue), and the strength of the magnetic field The X,Y and Z magnetic coils create a second magnetic field of varying intensity on top of the static magnetic field Because resonant frequency is proportional to the strength of the field, protons in different locations will then have different resonant frequencies The level of detail from an MRI scan is far higher than a CT scan or X-ray. Because radio waves have much less energy than X-rays, they are a non-iodising form of radiation, which makes an MRI much safer than X-rays and CT scans. 6. The Computer MRI stands for Magnetic Resonance Imaging, and uses information contained within the resonant signals to create an image of the patient's body The computer matches incoming resonant frequencies to the location of the individual protons Hydrogen protons in different kinds of tissue emit response signals of a different length, e.g. the response signal from bone is different from blood, which is different from the heart etc. Associated Risks There is no evidence that the magnetic waves used in MRI scans pose any health risks. However, accidents have previously occurred where unsecured metal objects in the scanning room have been drawn to the magnetic field of the MRI scanner and caused projectile injury. Strict protocols are in place by most health organisations to ensure this doesn't happen. Cancerous tissue emits a signal of greater length than non-cancerous tissue The computer matches the length of the signal to tissue type Sources http://www.cis.rit.edu/htbooks/mri/inside.htm http://web.mit.edu/invent/a-winners/a-damadian.html http://www.beyonddiscovery.org/content/view.article.asp?a=129 http://invigorate.royalsociety.org/ks4/a-window-on-the-brain/the-science-behind-the-scenes.aspx http://dev.ersnet.org/uploads/Document/8d/WEB_CHEMIN_2563_ I194523150.pdf http://www.nlm.nih.gov/medlineplus/ency/article/003335.htm http://commons.wikimedia.org/wiki/File:MRI_head_side.jpg Graphic Created by Acclarent UK http://www.balloonsinuplasty.co.uk/about-acclarent/ Original URL http://www.balloonsinuplasty.co.uk/visualisation-in-medicine/ VISUALISATION IN MEDICINE HOW MRI SCANS WORK Invented by Raymond Damadian - United States in1977 MRI Scan uses Magnetic Resonance Imaging (MRI) is an imaging technique used in medical settings to produce high quality images of the inside of the human body, like detailed pictures of organs, soft tissue, bone and virtually all internal body structures. MRI Scanner Patient Motorised Table Computer A Step by Step Guide The Inner Workings Radio Frequency Transmitter & Receiver Hydrogen Protons Sends and receives radio signals Water makes up 60-70% of the human body Water = molecules of Hydrogen and Oxygen atoms (H,O) The protons in Hydrogen atoms naturally spin on a variety of axes Main Magnetic Coil Creates a uniform magnetic field The Main Magnetic Coil X Magnetic Coils Create a varying magnetic field from left to right • The main magnetic coil creates a uniform magnetic field around the patient • The spinning Hydrogen protons in the patient's body will align with the magnetic field Y Magnetic Coils Create a varying magnetic field from O to bottom Z Magnetic Coils The Radio Signal Transmitter Create a varying magnetic field from head to toe The radio transmitter sends out radio wave pulses of varying frequencies When the frequency of the radio wave matches the frequency at which the proton is spinning, the proton absorbs the energy of the radio wave The additional energy causes the proton to tilt out of alignment with the magnetic field Output Uses The Radio Signal Receiver Differences in tissue type are shown Used to detect: as differences in colour contrast • When the pulse of the radio wave ends, the proton returns to alignment with the magnetic field, and emits a (resonant) signal of the same frequency as the radio signal it absorbed The resonant signal is picked up by the radio receiver The computer maps the location data and tissue type data to produce an image of the body Haemorrhages • Tumours Cysts Brain Infections Torn Ligaments And other Pathologies The X,Y and Z Magnetic Coils The resonant frequency of the atom depends on the type of atom (i.e. Hydrogen), the surrounding atoms (i.e. the type of tissue), and the strength of the magnetic field The X,Y and Z magnetic coils create a second magnetic field of varying intensity on top of the static magnetic field Because resonant frequency is proportional to the strength of the field, protons in different locations will then have different resonant frequencies The level of detail from an MRI scan is far higher than a CT scan or X-ray. Because radio waves have much less energy than X-rays, they are a non-iodising form of radiation, which makes an MRI much safer than X-rays and CT scans. 6. The Computer MRI stands for Magnetic Resonance Imaging, and uses information contained within the resonant signals to create an image of the patient's body The computer matches incoming resonant frequencies to the location of the individual protons Hydrogen protons in different kinds of tissue emit response signals of a different length, e.g. the response signal from bone is different from blood, which is different from the heart etc. Associated Risks There is no evidence that the magnetic waves used in MRI scans pose any health risks. However, accidents have previously occurred where unsecured metal objects in the scanning room have been drawn to the magnetic field of the MRI scanner and caused projectile injury. Strict protocols are in place by most health organisations to ensure this doesn't happen. Cancerous tissue emits a signal of greater length than non-cancerous tissue The computer matches the length of the signal to tissue type Sources http://www.cis.rit.edu/htbooks/mri/inside.htm http://web.mit.edu/invent/a-winners/a-damadian.html http://www.beyonddiscovery.org/content/view.article.asp?a=129 http://invigorate.royalsociety.org/ks4/a-window-on-the-brain/the-science-behind-the-scenes.aspx http://dev.ersnet.org/uploads/Document/8d/WEB_CHEMIN_2563_ I194523150.pdf http://www.nlm.nih.gov/medlineplus/ency/article/003335.htm http://commons.wikimedia.org/wiki/File:MRI_head_side.jpg Graphic Created by Acclarent UK http://www.balloonsinuplasty.co.uk/about-acclarent/ Original URL http://www.balloonsinuplasty.co.uk/visualisation-in-medicine/ VISUALISATION IN MEDICINE HOW MRI SCANS WORK Invented by Raymond Damadian - United States in1977 MRI Scan uses Magnetic Resonance Imaging (MRI) is an imaging technique used in medical settings to produce high quality images of the inside of the human body, like detailed pictures of organs, soft tissue, bone and virtually all internal body structures. MRI Scanner Patient Motorised Table Computer A Step by Step Guide The Inner Workings Radio Frequency Transmitter & Receiver Hydrogen Protons Sends and receives radio signals Water makes up 60-70% of the human body Water = molecules of Hydrogen and Oxygen atoms (H,O) The protons in Hydrogen atoms naturally spin on a variety of axes Main Magnetic Coil Creates a uniform magnetic field The Main Magnetic Coil X Magnetic Coils Create a varying magnetic field from left to right • The main magnetic coil creates a uniform magnetic field around the patient • The spinning Hydrogen protons in the patient's body will align with the magnetic field Y Magnetic Coils Create a varying magnetic field from O to bottom Z Magnetic Coils The Radio Signal Transmitter Create a varying magnetic field from head to toe The radio transmitter sends out radio wave pulses of varying frequencies When the frequency of the radio wave matches the frequency at which the proton is spinning, the proton absorbs the energy of the radio wave The additional energy causes the proton to tilt out of alignment with the magnetic field Output Uses The Radio Signal Receiver Differences in tissue type are shown Used to detect: as differences in colour contrast • When the pulse of the radio wave ends, the proton returns to alignment with the magnetic field, and emits a (resonant) signal of the same frequency as the radio signal it absorbed The resonant signal is picked up by the radio receiver The computer maps the location data and tissue type data to produce an image of the body Haemorrhages • Tumours Cysts Brain Infections Torn Ligaments And other Pathologies The X,Y and Z Magnetic Coils The resonant frequency of the atom depends on the type of atom (i.e. Hydrogen), the surrounding atoms (i.e. the type of tissue), and the strength of the magnetic field The X,Y and Z magnetic coils create a second magnetic field of varying intensity on top of the static magnetic field Because resonant frequency is proportional to the strength of the field, protons in different locations will then have different resonant frequencies The level of detail from an MRI scan is far higher than a CT scan or X-ray. Because radio waves have much less energy than X-rays, they are a non-iodising form of radiation, which makes an MRI much safer than X-rays and CT scans. 6. The Computer MRI stands for Magnetic Resonance Imaging, and uses information contained within the resonant signals to create an image of the patient's body The computer matches incoming resonant frequencies to the location of the individual protons Hydrogen protons in different kinds of tissue emit response signals of a different length, e.g. the response signal from bone is different from blood, which is different from the heart etc. Associated Risks There is no evidence that the magnetic waves used in MRI scans pose any health risks. However, accidents have previously occurred where unsecured metal objects in the scanning room have been drawn to the magnetic field of the MRI scanner and caused projectile injury. Strict protocols are in place by most health organisations to ensure this doesn't happen. Cancerous tissue emits a signal of greater length than non-cancerous tissue The computer matches the length of the signal to tissue type Sources http://www.cis.rit.edu/htbooks/mri/inside.htm http://web.mit.edu/invent/a-winners/a-damadian.html http://www.beyonddiscovery.org/content/view.article.asp?a=129 http://invigorate.royalsociety.org/ks4/a-window-on-the-brain/the-science-behind-the-scenes.aspx http://dev.ersnet.org/uploads/Document/8d/WEB_CHEMIN_2563_ I194523150.pdf http://www.nlm.nih.gov/medlineplus/ency/article/003335.htm http://commons.wikimedia.org/wiki/File:MRI_head_side.jpg Graphic Created by Acclarent UK http://www.balloonsinuplasty.co.uk/about-acclarent/ Original URL http://www.balloonsinuplasty.co.uk/visualisation-in-medicine/