CT arthrography shows promise for SLAP tear detection

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Type IV SLAP lesion correctly diagnosed in 23-year-old woman. H=humeral head. Axial multidetector CT arthrograms shows anterior-to-posterior extension of contrast medium (arrowheads) into superior labrum. Arrow=metal anchoret, C=coracoid process, G=glenoid labrum. Image and caption courtesy of the Radiological Society of North America.
CT arthrography may offer comparable sensitivity and specificity as MR arthrography for the detection of repeat superior labral anterior-to-posterior (SLAP) tears, according to a retrospective analysis published this month in Radiology.

A multinational team from the Mayo Clinic in Rochester, Minn., the Istituto Clinico Humanitas in Milan, Italy, the Istituto Clinico Citta di Brescia in Brescia, Italy, and the University of Parma in Parma, Italy, reviewed the findings of patients who underwent multidetector CT arthrography between April 2003 and December 2007 at a tertiary-care center and subsequently underwent conventional arthroscopy within 30 days.

The cohort was comprised of patients who had previously undergone shoulder surgery and were clinically suspected of having a recurrent tear.

“Inclusion criteria were prior surgical repair of SLAP lesions, placement of some type of metallic implant as part of the repair, and clinical findings suggestive of recurrent SLAP tear,” the authors wrote.

The clinicians reviewed the charts of 45 consecutive patients who fulfilled these criteria.

“Because our institution has a large referral base of professional athletes, all of the patients in the study were professional athletes (volleyball, basketball, baseball, rugby),” the authors wrote. “There were no patients at our institution who met the inclusion criteria and were not professional athletes.”

All patients were injected with iodixanol (Vispaque 320, Amersham Health) contrast material into the glenohumeral joint and were imaged with a 16-slice CT system (Sensation 16, Siemens Healthcare). All images were downloaded to a Siemens’ Volume Zoom Wizard workstation for application of advanced visualization technology and review.

Two musculoskeletal radiologists created multiplanar reformatted images, including coronal and transverse reformatted images of the joints, at the workstation. They then reviewed all the imaging studies independently and categorized the depicted SLAP lesions.

Arthroscopic examinations of the shoulder were performed by one of two orthopedic surgeons less than 30 days after multidetector CT arthrography and was used as the reference standard for determining shoulder abnormalities.

“Multidetector CT arthrography had very good sensitivity (95 percent) and specificity (88 percent) for the detection of recurrent SLAP tears in professional athletes who had previously undergone surgical repair of SLAP tears,” the authors wrote.

The researchers noted that the high sensitivity they observed is comparable with the reported sensitivity of MR arthrography.

“However, MR imaging has some disadvantages compared with CT,” the authors noted. MR examinations take longer to perform; are performed with a smaller bore gantry, which might not accommodate some patients; and cannot be performed owing to claustrophobia in 1 percent to 2 percent of patients. Also, MR imaging is more prone to yield metallic artifacts, which may be substantive postoperatively in patients with metallic clips and anchors.”

Although the patient population of professional athletes was highly selective and specific, the researchers expressed confidence in their CT arthrography results.

“Overall, the results in our study suggest that multidetector CT arthrography is robust for the detection and classification of recurrent SLAP tears,” they concluded.