3D MRI comparable to 2D for diagnosing meniscal knee injuries

Three-dimensional (3D) MRI is similar to 2D for diagnosing meniscus knee injuries, but may be able to cut down on image acquisition time, reported authors of a Nov. 20 study published in Radiology.

Three-dimensional MRI has shown to nearly eliminate the partial volume averaging effects which hamper 2D imaging, among other benefits. However, recent research has found 3D MRI can result in poor diagnostic performance for depicting knee joint problems, wrote Delaram Shakoor, of Johns Hopkins University in Baltimore, and colleagues.

Thirty-one studies consisting of 1,743 3D knee MRI exams were included alongside 23 additional 2D MRI studies. All were published between 1985 and 2017. Studies done prior to 2008 used gradient-echo (GRE) sequences, while those after 2011 utilized fast spin-echo (FSE).

Shakoor and colleagues found comparable results for sensitivity and specificity of 3D and 2D sequences performed with 3T MRI or lower. In 3D FSE, sensitivity and specificity were 90 percent and 91 percent, respectively. Those results were “comparable” to that of 3D GRE and 2D MRI. Shakoor et al. noted 3D FSE achieved a higher sensitivity (85 percent) than 3D GRE for imaging lateral meniscal injuries.

“Lateral meniscal injuries have been described to be more difficult to detect by using a conventional MRI protocol,” the authors wrote.  “Therefore, it can be assumed that the difference between resolution and contrast of GRE and 3D FSE sequences would have a greater impact on the sensitivity of MRI for the identification of lateral meniscal injuries."

After a sensitivity analysis, the team found a multiplanar reformatting sequence could improve the specificity of 3D sequences—similar to findings of prior studies. Overall, they decided more research would be needed to see if 3D MRI could fully replace its 2D counterpart.

“Although our meta-analysis shows promising results regarding the diagnostic performance of 3D sequences, further investigations are required to determine whether 3D sequences could replace 2D sequences in clinical practice for depicting other pathologic abnormalities of the knee joint,” the authors concluded.