MRI may determine severity, location of abnormalities in shoulder instability
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WAIKOLOA, Hawaii — MRI can be used to determine the chronicity, severity and location of abnormalities in patients with traumatic shoulder instability, according to a presenter at Orthopedics Today Hawaii.
With labral tear as the “hallmark of instability on MRI,” previously published research has shown 1.5 or 3 Tesla MRI alone provides good sensitivity and specificity for identifying labral tears, while MR arthrography provides slightly better sensitivity and specificity and is typically added for equivocal findings on standard MRI or postoperative settings, according to Pamela J. Lund, MD. She said 3 Tesla MRI and MR arthrography provide better sensitivity and specificity compared with standard MRI.
“Remember, according to the literature, low field, less than 0.5 Tesla, open MRIs are not going to give you good sensitivity for labral tears, so be aware of that when you’re looking at your MRI studies,” Lund said in her presentation, here.
Use a dedicated shoulder coil
Lund said it is important for surgeons to obtain high-field MRIs when possible. She added that she likes to use a dedicated shoulder coil that transmits and receives signals with an expected total scan time of 15 to 20 minutes.
Source: Pamela J. Lund, MD
“We do fluid- and fat-sensitivity sequences, as we do in all our MRI studies,” Lund said.
In patients with shoulder instability undergoing an arthrogram, Lund said she obtains an abduction external rotation (ABER) view, which provides long axis optimal images of the anterior-inferior labrocapsular complex and shows the biceps labral complex in the overhead “functional” shoulder position.
“We also do an oblique view if the patient cannot perform the ABER with a recent dislocation,” she said.
Imaging for bipolar bone loss
The published literature has shown both CT and MRI scans are accurate for assessing patients with both glenoid bone loss and Hill-Sachs lesions, also known as bipolar bone loss, according to Lund.
“For measuring glenoid bone loss, you can pick your poison,” Lund said. “Some of these methods, of course, use the opposite shoulder for superimposing requiring superimposition of the right and left glenoids on one another and many are CT techniques using radiation, so those are not as easy to use practically. Soterios Gyftopoulos, MD, and colleagues found that bipolar bone loss can be accurately evaluated on MRI using the on-track off-track method.
According to Lund, "When you’re doing the bipolar type of measurements, you’re going to be using the combining measurements of the Hill-Sachs interval and best fit circle and the surface area method for glenoid bone loss.”
- Reference:
- Lund PJ. Shoulder MRI interpretation: Traumatic and atraumatic instability. Presented at: Orthopedics Today Hawaii. Jan. 9-13, 2022; Waikoloa, Hawaii.
- For more information:
- Pamela J. Lund, MD, can be reached at SimonMed Imaging, 9201 E. Mountain View Road, Suite 137, Scottsdale, AZ 85258; email: plund@simonmed.com.
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