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MRI is a well-developed medical imaging technology, being the imaging modality of choice for most soft tissue and functional imaging indications.
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The science and application of MRI continue to advance, with several recent developments having notable implications for the practice of dentistry.
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Although MRI has traditionally been considered prohibitively costly for use in routine dental practice, many of the recent technological advancements have the potential to greatly reduce the cost associated
MRI for Dental Applications
Section snippets
Key points
Established MRI techniques applied to dental indications
The first MRI was acquired by Lauterbur in 1973.4 With the evolution of the commercial medical MRI in the 1980s, several applications were performed in medical imaging (ie, cardiac, abdominal, cranial MRI).5 Broadly, in medicine, MRI is fast outpacing any other modality for in vivo displaying of soft tissues and function in the human body without any invasive procedure and ionizing radiation.6 Because of the inability of conventional MRI to image hard tissues, conventional MRI techniques in
A brief overview of MRI physics and stepwise description of how an MRI is obtained
Before recent developments in MRI research specific to dental imaging and as a matter of review are discussed, the following is a brief discussion of how diagnostic images are obtained using MRI.
The magnet
The largest component of a typical MRI scanner is the magnet itself, which is in essence a large insulated vessel containing wire windings and cryogen (ie, liquid helium) to enable a superconducting magnet. The manufacturing process for magnets with a small bore size requires less wire and cryogen and is therefore smaller, lighter, and cheaper. These smaller magnets facilitate the development of scanners that are dedicated in their purpose, such as dedicated head, knee, wrist, breast, or small
Body and surface coils
Clinical MRI scanners are built with large RF coils within the bore of the scanner to transmit radio waves that energize the tissue being imaged. These RF coils are typically referred to as body coils, because they are built to energize the entire body, regardless of the anatomy being imaged. To record the RF signal released by the patient, anatomy-specific receiver or surface coils are placed adjacent to the anatomy being imaged. Per the discussion earlier, MRI scanners that are anatomy
Gradient coils
Gradient coils are located in the body of the magnet proper. The function of these coils is to impart a small change or gradient within the main magnetic field in each of the 3 dimensions of the patient, referred to as x-, y-, and z-directions. While the magnet is scanning, these gradient coils will be used to rapidly alter the local magnetic field, with larger gradients producing a greater ability to record spatial information. The rapid changes in gradients are responsible for producing the
Pulse sequences
A pulse sequence is the code that instructs the MRI scanner in how to image the patient, similar to how software instructs a computer how to operate. Over time, new pulse sequences are developed to address new approaches to imaging, and clinically robust ones are continuously updated. Also similar to computer software, matching the software (ie, pulse sequence) and the hardware (ie, magnet and coil) with each other is critical to get maximal production and efficiency for a given MRI scanner.
Computing power and image reconstruction
In recent years, the computing power of personal computers built and priced for the consumer market have become adequate in handling most of the image reconstruction needs, thus decreasing the cost of MRI scanning systems. Only a few years ago MRI systems required expensive and purpose-built computer hardware to take the raw signals from the scanner and construct images from them. In addition, the algorithms for image reconstruction have improved, resulting in drastic reductions in time
Summary
In the last several years, major technological advancements involving multiple components of MRI have occurred. Together, they are enabling the hardware of MRI to become smaller, less complicated, cheaper, and tailored to acquiring images of teeth and supporting structures. Research investigating the clinical utility of this technology to address problems in dentistry is just now initiating, and consequently, the application of MRI in dentistry is feasible with potential yet to be explored.
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Disclosure: The authors have nothing to disclose.