Conventional magnetic resonance imaging may be an effective alternative to minimally-invasive magnetic resonance arthrography, according to investigators.
Although they found an increased accuracy for the detection and localization of labral tears with magnetic resonance (MR) arthrography when compared to magnetic resonance imaging (MRI), the differences were not statistically significant.
Colin D. Strickland, MD, presented the findings at the 2010 American Roentgen Ray Society Annual Meeting in San Diego.
“Conventional hip MRI and MR arthrogram studies revealed no significant difference between the two imaging techniques in the detection of labral tears for any of the three readers in our study group,” Strickland stated in an American Roentgen Ray Society (ARRS) press release.
A retrospective review
Strickland’s team performed a retrospective review, identifying 30 patients who underwent preoperative imaging with both conventional hip MRI – including small field-of-view images of the symptomatic side – and MR arthrography prior to hip arthroscopy. The median time between MRI and MR arthrography was 59 days, and the median time between MR arthrography and hip arthroscopy was 68 days.
The studies for each patient were independently reviewed by two musculoskeletal radiologists and one musculoskeletal radiology fellow for the presence and location of acetabular labral tears. The investigators then compared the results to arthroscopic findings for tear presence and location, with statistical analysis performed via the McNemar test.
All of the subjects had arthroscopically proven labral tears. Although MR arthrogram displayed slightly better performance than conventional hip MRI, no significant difference was revealed between the two imaging techniques regarding the detection of labral tears for any of the three readers.
The investigators found similar results regarding the detection of labral tears and saw no detected difference regarding the accuracy of the localization of tears to the correct quadrant of the acetabulum.
A possible alternative
According to Strickland, the results show that conventional MRI could possibly be an alternative — not a full replacement — for MR arthography.
“Minimally-invasive MR arthrography remains the preferred test for the evaluation of suspected hip labral tears,” Strickland stated. “However, our study suggests that conventional, noninvasive MRI may detect a large percentage of these tears.”
Strickland’s group stressed that further study was needed to determine whether conventional MRI is an acceptable alternative, especially in the evaluation of non-specific hip pain.
Strickland CD, Blankenbaker D, Davis K, et al. Is conventional MRI as accurate as MR arthrography of the hip? Presented at the 2010 American Roentgen Ray Society Annual Meeting. May 2-7, 2010. San Diego.
The authors raise an interesting point in that MRI may provide comparable and "sufficient" information regarding the status and location of labral tears in the hip when compared with MRA. MRI has the advantage of showing an effusion (which has clinical implications) and an effusion may outline the labrum quite well. MRA has the potential advantage of adding a local anesthetic with the contrast medium thereby providing additional clinical information based on the response to an injection challenge. I find this to be of value whenever it remains unclear that the causative pathology is intra-articular.
But in the many patients with classic radiographic findings for femoroacetabular impingement with chondrolabral dysfunction and a matching history and physical examination, I find MRI to be a practical alternative. Patient discomfort and potential iatrogenic damage from an intra-articular injection are avoided, as are possible adverse effects from the instillation of a local anesthetic agent.
Two other points merit consideration. Current MRI and MRA technology can detect labral tears much better than chondral pathology, yet the latter appears to be a more significant determinant of clinical outcomes. Moreover, we are seeing some recent studies detecting asymptomatic labral tears on MRI/MRA, so it behooves us to proceed with due caution as we interpret these findings. Brings us back to "treat the patient, not the
Dean K. Matsuda, MD
Director of Hip Arthroscopic Surgery
Co-Chair of Sports Medicine
Kaiser-Permanente WLA Medical Center
Los Angeles, Calif.