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MRI Procedures and Anatomy of Upper Extremity Questions and Answers
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MRI Procedures and Anatomy of Upper Extremity
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MRI Procedures and Anatomy of UpperExtremity
T/F The SNR of the shoulder is largely dependent on the quality and type of coil used. -
answer True--dedicated shoulder coils return a much higher and uniform signal than a
surface coil.
How and why is using a dedicated shoulder coil beneficail for the image? - answer-
Increase in SNR
-thinner slices and finer matrices can be used to achieve good spatial resolution w/o
increasing scan time
Angling more than 45 degrees on a shoulder can make some systems dow what to an
image? - answercause coronal/oblique to be seen as a sagittal/oblique and alter the
image to make a right shoulder look like a left and vice versa.
What are the pulse sequences of choice when scanning a shoulder? - answerSE/FSE
An MRI of the shoulder, what pulse sequences are useful to visualize joint fluid? -
answerCoherent GRE and STIR
To reduce phase ghosting during a shoulder MRI, where should pre-satruation bands
(sat bands) be placed? - answerInferior and medial to the shoulder
What are the main sources of artifacts during a shoulder MRI? - answerPatient
movement and flow motion from subclavian vessels
In a shoulder MRI, what minimizes flow artifact but increases signal in vessels and the
minimum TE so it isnt beneficial in T1 sequences---but it effectively increases the
contrast of synovial fluid in T2 and T2* images? - answerGMN=gradient moment nulling
If too much obliquity is used in the coronal oblique and axial imaging of a shoulder--it
can cause some systems to do what? causing? unless this is used? - answer-
automatically swap the direction of phase and frequency
-causing aliasing
-unless oversampling is used
On an MRI of the shoulder, what can cause some systems to see a coronal/oblique as a
sagittal/oblique and alter the image to make a right shoulder look like a left and vice
versa? - answerAngling more than 45 degrees
, To minimize aliasing on shoulders, how should phase encodings run on axials and
sagittal/obliques? and this way on coronal/obliques? - answer-Anterior-Posterior on
axials and sagittal/obliques
-Superior-Inferior on coronal/obliques
On a shoulder, what can be used to minimize artifact from the medial edges of the coil?
- answerSpatial pre-saturation pulses
What phenomena causes and increased signal intensity in tendons in a shoulder in
short TE sequences when tendons are oriented at an angle of _______ degrees to the
main field? - answer-Magic Angle
-55 degrees
If the phenomenon of Magic Angle occurs during a shoulder exam, what does it do to
tendons and why? Why is this a disadvantage? - answer-Normally tendons produce
little to no signal, but at an angle of 55 degrees to main field--this causes an increase in
signal intensity of tendons
-It happens because at this angle the T2 relaxation time increases causing high signal
intensity when using short TE.
-Disadvantage is misdiagnosis--because it can mimic pathology such as tendonitis in
normal tendons.
What are 2 types of abnormalities seen on a shoulder arthrogram, that cause 95% of
anterior instability--and leads to multidirectional instability? - answer-Bony Bankart
Lesion
-Labral Bankart
What 4 muscles connect together in the shoulder to make up the rotator cuff? -
answer1. Supraspinatus muscle
2. Infraspinatus muscle
3. Teres minor muscle
4. Subscapularis muscle
What is the purpose of the 4 muscles that make up the rotator cuff? - answerThese
muscles together stabalize the upper arm bone to the shoulder sockey and allow the
wide ROM in the shoulder.
What is the ratio of saline to contrast in an arthrogram exam of the shoulder? Where is
this solution injected? - answer1:100----in the joint capsule of shoulder
Arthrography of the shoulder is used to diagnose what kinds of problems? - answer-
rotator cuff tears
-glenoid labral disruption
-chondral defects
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