3T MRI alone outperformsenhanced MR arthrography

A Duke University study has established that unenhanced 3T MR imaging can deliver the same diagnostic accuracy as contrast-enhanced 3T MR arthrography of the shoulder, but without the associated pain, radiation, and risk of adverse contrast reactions.

The combined MRI-arthrography exam of suspicious shoulder labrum injury relies on fluoroscopy as well as iodine and gadolinium contrast media. Though considered highly accurate and efficacious, MR arthrography may be too resource-intensive to remain desirable in today’s busy radiology practice.

The added radiation and use of contrast are also of concern to patients, said principal investigator Dr. Jeffrey Browne. Three-T MR without intra-articular contrast injection can turn an invasive exam into a speedier noninvasive one, according to Browne, who was a musculoskeletal radiology fellow at Duke during the study. He is now a radiologist at Raleigh Radiology in North Carolina.

“Patients who are reluctant to undergo an arthrogram now have the option of undergoing a noninvasive exam while still allowing the radiologist to make an accurate diagnosis,” Browne told Diagnostic Imaging.

Thirty-five patients with shoulder pain were given both unenhanced 3T MR and contrast-enhanced 3T MR arthrography. Results were subjected to blind interpretation by three experienced musculoskeletal radiologists.

Nonenhanced and contrastenhanced 3T MR detected 27 and 31 labral tears, respectively. Arthrography detected 18 tears that were later confirmed by arthroscopic surgery in 14 of 15 patients.

The sensitivity for nonenhanced and enhanced MR at 3T was identical at 78%, while their specificity rates were 67% for the nonenhanced and 100% for the enhanced studies. The sensitivity for each portion of the labrum was also identical on both MR techniques: superior 67%, anterior 100%, and posterior 86%.

Interpretations of nonenhanced and enhanced MR on 11 of the patients who received arthroscopy matched surgical results. Tears in four patients with discordant findings were found inconsistently on either technique. None of the differences between the two 3T MR techniques for the diagnosis of labral pathology were statistically significant.

Preliminary findings were reported at the 2008 American Roentgen Ray Society meeting.

-By H.A. Abella