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Imaging of osseous and cartilaginous intraarticular bodies in the knee: comparison of MR imaging and MR arthrography with CT and CT arthrography in cadavers.

PURPOSE
To compare magnetic resonance (MR) imaging and MR arthrography with computed tomography (CT) and CT arthrography in the detection of intraarticular bodies in the knee.


MATERIALS AND METHODS
Cuboid (3- or 6-mm-long sides) osseous and cartilaginous bodies were implanted in 16 cadaveric knee specimens. MR imaging was performed with T1-weighted spin-echo (SE), T2-weighted SE, proton-density-weighted SE, gradient recalled acquisition in the steady state (GRASS), and spoiled GRASS sequences. MR arthrography was performed in two phases with saline and 2 mmol/L gadopentetate dimeglumine. CT and CT arthrography were performed in the transaxial plane.


RESULTS
MR arthrography yielded the highest accuracy for the detection of osseous and cartilaginous bodies combined (92%) and was significantly (P < .01) better than MR imaging (57%-70%), CT arthrography (80%), and CT (74%). Accuracy of CT arthrography was significantly better than that of MR imaging and that of CT. Accuracy of saline-enhanced MR arthrography was significantly inferior (P < .001) to that of gadolinium-enhanced MR arthrography.


CONCLUSION
MR arthrography is the best imaging technique for detection of individual intraarticular bodies. CT arthrography is the second most accurate method. Spoiled GRASS and T2-weighted SE sequences are the most accurate at MR imaging. The presence of intraarticular fluid and performance of saline-enhanced MR arthrography improve detectability of intraarticular bodies.