Lainiala et al [39] found a higher sensitivity for detecting ARMD pseudotumors for studies performed within 3 months before revision surgery (88% sensitivity, 78% specificity), and a lower sensitivity for studies obtained >1 year before revision surgery (sensitivity 29%, specificity 97%). It was suggested that studies >1 year not be used for clinical decision making or planning revision surgery. Combined US and MARS-MRI studies: Comparison to surgical results suggests combining US and MARS-MRI improves accuracy. Small numbers of lesions detected on US are not visible on MRI, and some lesions seen on MRI are not apparent on US [41,52]. Wear: MRI is the most accurate imaging method for assessing wear induced synovitis [131]. Synovial characteristics may reflect the implant type and wear severity [9,142]. Osteolysis: As noted above, there are conflicting reports regarding the optimal study for detecting osteolysis. Walde et al [126] demonstrated in a cadaver model that MRI could detect osteolysis with greater sensitivity than CT. The sensitivity for detecting lesions was 51.7% for radiography, 74.7% for CT, and 95.4% for MRI. CT was more accurate; however, than MRI for measuring lesion volume [126]. Robinson et al [134]; however, demonstrated a reduced sensitivity (27%) and specificity (1%) of MARS-MRI in comparison with CT-MAR for detecting osteolysis associated with painful MoM hip prostheses. Morozov et al [143] evaluated 20 symptomatic patients with MoP prostheses with corrosion at the head-neck taper. Comparison of MRI and surgical findings found MRI to have limited sensitivity for either acetabular (11.1% sensitivity) or femoral (33.3% sensitivity) osteolysis [143]. There is insufficient literature documenting the additional benefit of MRI with IV contrast, relative to noncontrast MRI, in this population.
Imaging after Total Hip Arthroplasty PCAs. Lainiala et al [39] found a higher sensitivity for detecting ARMD pseudotumors for studies performed within 3 months before revision surgery (88% sensitivity, 78% specificity), and a lower sensitivity for studies obtained >1 year before revision surgery (sensitivity 29%, specificity 97%). It was suggested that studies >1 year not be used for clinical decision making or planning revision surgery. Combined US and MARS-MRI studies: Comparison to surgical results suggests combining US and MARS-MRI improves accuracy. Small numbers of lesions detected on US are not visible on MRI, and some lesions seen on MRI are not apparent on US [41,52]. Wear: MRI is the most accurate imaging method for assessing wear induced synovitis [131]. Synovial characteristics may reflect the implant type and wear severity [9,142]. Osteolysis: As noted above, there are conflicting reports regarding the optimal study for detecting osteolysis. Walde et al [126] demonstrated in a cadaver model that MRI could detect osteolysis with greater sensitivity than CT. The sensitivity for detecting lesions was 51.7% for radiography, 74.7% for CT, and 95.4% for MRI. CT was more accurate; however, than MRI for measuring lesion volume [126]. Robinson et al [134]; however, demonstrated a reduced sensitivity (27%) and specificity (1%) of MARS-MRI in comparison with CT-MAR for detecting osteolysis associated with painful MoM hip prostheses. Morozov et al [143] evaluated 20 symptomatic patients with MoP prostheses with corrosion at the head-neck taper. Comparison of MRI and surgical findings found MRI to have limited sensitivity for either acetabular (11.1% sensitivity) or femoral (33.3% sensitivity) osteolysis [143]. There is insufficient literature documenting the additional benefit of MRI with IV contrast, relative to noncontrast MRI, in this population.