Magnetic Resonance Imaging

Magnetic Resonance Imaging


Musculoskeletal



Basic Information image



Overview and Goal(S)




Magnetic resonance imaging (MRI) produces images based on the magnetic properties of the hydrogen protons within the body.


MRI provides exquisite detail of the soft tissues. Osseous structures are also well visualized, particularly bone marrow and subchondral bone. However, due to the minimal resonance produced by normal cortical bone, periarticular proliferation and small osseous bodies can be easily overlooked compared with computed tomography (CT).


MRI differs from CT in that multiple scan planes are acquired rather than being reconstructed from a single axial plane. This leads to much longer scanning times.


The patient is placed within a relatively strong magnetic field (see “Equipment” below), aligning the hydrogen protons of the body.


A pulse sequence is applied to the anatomic area of interest, and the response of the protons to that pulse sequence produces an image. Within the pulse sequence, a radiofrequency (RF) pulse is introduced into the patient from a transmit coil, energizing the tissue. As the tissue reverts to its original state, RF energy is emitted from the patient and recorded by a receiving coil.


The differences in the magnetic properties of tissues are demonstrated by using multiple types of pulse sequence. By altering these parameters, the contrast of various tissues is altered, allowing differentiation of anatomic structures.


Spin-echo sequences use multiple introductions of RF signal that include a 180-degree rephasing pulse. This rephasing pulse corrects for magnetic susceptibility.


The most commonly used scanning sequences are:











Equipment, Anesthesia


Positioning:



Equipment:


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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Magnetic Resonance Imaging

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