This document provides an introduction to magnetic resonance imaging (MRI) technology. It discusses the basic principles of how MRI works, including how hydrogen nuclei respond to strong magnetic fields and radiofrequency pulses to produce images. The document outlines the main components of an MRI machine, including different types of coils used. It also covers the principles behind nuclear spin, magnetism, and how protons align in magnetic fields. Common uses of MRI in dentistry are described, such as for detecting infections, cysts, tumors, and temporomandibular joint disorders. Contrast agents used to improve tissue visibility are also mentioned.

1. ADVANCED IMAGING

2. Magnetic Resonance Imaging

3. INTRODUCTION to MRI
 Stands for Magnetic Resonance Imaging
 Latest non-invasive imaging modality that uses electrical
signals generated from response of hydrogen nuclei to strong
magnetic field & radiofrequency pulses to produce an image.
 Totally diff physical principle than CT
 Radiofrequency wave/ Pulse
 No X-Rays are used.
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4. INDICATIONS:
CONTRAINDICATIONS
Dental considerations
ADVANTAGES
DISADVANTAGES
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5. Parts of an MRI machine
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6. COILS:
A coil is used to create a magnetic field or to detect a
changing magnetic field by voltage induced in the
wire.
It is usually a physically small antenna.
The perfect coil produces a uniform magnetic field
without significant radiation.
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7. TYPES OF COILS
Gradient coils
Radiofrequency
coils
Shim coils
Used to produce controlled
variations in the main
magnetic field to provide
spatial localization of the
signals
To receive & or transmit the
RF signal of frequency range
of 3 - 300 MHz
Provide auxillary magnetic fields
in order to compensate for
inhomogeneities in the main
magnetic field of the MRI
machine
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8. Principles of MRI

9. NUCLEAR SPIN , MAGNETISM, MAGNETS
Atomic nuclei have a property called – NUCLEAR SPIN.
Human body is almost 70% of water, out of which
HYDROGEN is the major component.
Hydrogen nucleus has a solitary proton, its single moving
charge creates a MAGNETIC FIELD.
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10. Tightly bound hydrogen atoms, such as those present
in bone, do not align themselves with the external
magnetic field & do not produce a usable signal.
Loosely bound / mobile hydrogen atoms such as those
present in soft tissues & liquids tilt & align to produce
a detectable signal.
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12.  Spin up
 Spin down

13.  – precession.
 Larmor frequency.
Precession

14.  Radiofrequency pulse (RF pulse)

15. If the RF pulse is of sufficient intensity, it will rotate the net
tissue magnetization vector into the transverse plane (XY
plane) which is perpendicular to the longitudinal alignment
(Z plane) & cause all the protons to precess in phase.
This is called as 900 RF pulse or flip angle of 900.
If it is 1800 – 1800 RF pulse.

16. 90 degree RF pulse
180 degree RF pulse

17.  Relaxation include 2 independent processes:
 Spin lattice relaxation
 Spin spin relaxation

18. Spin lattice relaxation
T1 – time taken for 63% of the
nuclei to return to the lower
energy state following termination
of RF pulse

19.  Tissue with short T1 - intense MR signal, bright white.
 Long T1 - low-intensity signal, dark.

20. Spin spin relaxation
Rate of loss of transverse magnetization - T2 relaxation time.

21.  Used to improve the visibility of internal
body structures.
 Most commonly used - gadolinium-based.
 Gadolinium diethylene triamine penta
acetic acid.
Contrast enhancement

22. Intravascular
 Gadolinium (Gd)
 Iron oxide
 Manganese
Oral
 Barium sulfate
 Natural products;
 Blueberry & Green
tea

23. Applications in dentistry

24. Infections

25. Cyst

26. Dentigerous cyst

27. Tumor

28. Keratocystic Odontogenic Tumor:

29. TMJ disorders

30. Special MR techniques

31. MR Angiography

32. MR Sialography

33. THANK YOU….