This document provides an overview of magnetic resonance imaging (MRI). It explains that MRI uses powerful magnets to produce detailed 3D anatomical images without radiation by detecting the energy released as protons in the body realign with the magnetic field. The document discusses the history of MRI's development, how MRI works, examples of its use in examining various parts of the human body like the brain and soft tissues, and some risks like exposure to strong magnetic fields.

1. NUCLEAR
PHYSICS
COURSE INSTRUCTOR : DR. WASEEM AHMAD
PRESENTED BY : MEHAK TARIQ
PRESENTATION ON : MAGNETIC RESONANCE
IMAGING

2. MAGNETIC RESONANCE IMAGING
• Magnetic Resonance Imaging (MRI) is a non-invasive imaging
technology that produces three dimensional detailed anatomical
images.
• It is often used for disease detection, diagnosis, and treatment
monitoring.
• It is based on sophisticated technology that excites and detects the
change in the direction of the rotational axis of protons found in
the water that makes up living tissues

3. HISTORY OF MRI
• Felix Bloch and Edward Purcell were awarded the 1952 Nobel
Prize in Physics for their discovery of nuclear magnetic
resonance (NMR) and subsequent researches. Although the term
NMR is still used in research environments, the term magnetic
resonance imaging (MRI) is preferred in clinical environments
to prevent patients associating the technique with ‘harmful
nuclear radiation’
• MR imaging was invented by Paul C. Lauterbur who developed
a mechanism to encode spatial information into an NMR signal
using magnetic field gradients in September 1971; he published

4. HOW DOES MRI WORK?
• MRIs employ powerful magnets which produce a strong
magnetic field that forces protons in the body to align with that
field.
• When a radiofrequency current is then pulsed through the
patient, the protons are stimulated, and spin out of equilibrium,
straining against the pull of the magnetic field.
• When the radiofrequency field is turned off, the
MRI sensors are able to detect the energy released as the
protons realign with the magnetic field.
• The time it takes for the protons to realign with the magnetic

5. • field, as well as the amount of energy released, changes depending on the
environment and the chemical nature of the molecules.
• Physicians are able to tell the difference between various types of tissues
based on these magnetic properties
• To obtain an MRI image, a patient is placed inside a large magnet and must
remain very still during the imaging process in order not to blur the image.
• Contrast agents (often containing the element Gadolinium) may be given to
a patient intravenously before or during the MRI to increase the speed at
which protons realign with the magnetic field.
• The faster the protons realign, the brighter the image.

6. MRI LOOKS
• The
traditional MRI unit is a
large cylinder-shaped tube
surrounded by a circular
magnet.
• You will lie on a table that
slides into the center of the
magnet.
• Some MRI units, called
short-bore systems, are
designed so that the
magnet does not

7. HUMAN BODY MRI

8. WORK IN HUMAN BODY

9. USES OF MRI
• The following are examples in which an MRI scanner would be
used:
• Anomalies of the brain and spinal cord. However, MRI is more
expensive than x-ray imaging or CT scanning.
• Tumors, in various parts of the body
• MRI scanners are particularly well suited to image the non-bony
parts or soft tissues of the body.
• One kind of specialized MRI is functional Magnetic Resonance
Imaging (fMRI.) This is used to observe brain structures and

10. • Breast cancer screening for women who face a high risk of breast
cancer
• Injuries or abnormalities of the joints, such as the back and knee
• Certain types of heart problems
• Diseases of the liver and other abdominal organs
• The evaluation of pelvic pain in women, with causes
including fibroids and endometriosis

11. ARE THERE RISKS?
• Although MRI does not emit the ionizing radiation that is found
in x-ray and CT imaging,
• It does employ a strong magnetic field.
• The magnetic field extends beyond the machine and exerts very
powerful forces on objects of iron, some steels, and other
magnetizable objects;
• It is strong enough to fling a wheelchair across the room.
• Patients should notify their physicians of any form of medical or
implant prior to an MR scan.

12. • Noise—loud noise commonly referred to as clicking and
beeping, as well as sound intensity up to 120 decibels in certain
MR scanners, may require special ear protection.