MR parameters for imaging titanium spinal instrumentation.

The presence of stainless steel implants along a spinal column causes extreme distortion of data collected by magnetic resonance (MR) imaging. The recent availability of titanium alloy spinal instrumentation systems suggests that MR imaging evaluation of the instrumented spine may now be feasible. The objective of this study was to perform MR imaging examinations on spines implanted with titanium alloy instrumentation and to determine the parameters that yield the highest quality images with the least amount of artifact. A titanium pedicle screw construct was implanted into the lumbar spine of two fresh human cadaveric specimens. Sequential spin echo MR scans were performed using various TE and TR ratios on each intact specimen. The resultant images were quantitatively graded for clarity of adjacent soft tissue and osseous structures. Excellent T1- and T2-weighted images with well-defined neural structures were obtained with minimal artifact. The optimal T1-weighted image was obtained with TE = 16 and TR = 500-600, whereas the optimal T2-weighted image was obtained with TE = 60 and TR = 1,300-1,600. By using appropriate settings, high-quality MR scans in both the T1- and T2-weighted modes can be obtained with minimal metal artifact.