Reducing Metallic Artifacts in Postoperative Spinal Imaging: Usefulness of IDEAL Contrast-enhanced T1- and T2-weighted MR Imaging—Phantom and Clinical Studies

Abstract

To prospectively compare the effectiveness of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) T2-weighted and contrast material-enhanced T1-weighted magnetic resonance (MR) imaging with that of a conventional MR imaging protocol in minimizing metallic artifacts in phantoms and in patients with metallic hardware after spinal surgery. Institutional review board approval and informed consent were obtained for this study. Coronal T1- and T2-weighted MR images of six titanium alloy pedicle screws in an oil bath containing tubes filled with diluted gadolinium contrast medium were obtained with frequency-selective fat saturation (FSFS) and IDEAL. Axial T2-weighted and contrast-enhanced T1-weighted MR imaging of the spine was performed with FSFS and IDEAL at 22 lumbar levels in 19 patients. Two musculoskeletal radiologists qualitatively analyzed the images in terms of the visualization of paravertebral muscle and the spinal canal region, uniformity of fat saturation, and noise. The paired images were rated by using a five-point scale. For the quantitative study with phantoms, the short- and long-axis lengths of metallic artifacts were determined on signal intensity profiles. In the phantom study, metallic artifact size was markedly decreased in the IDEAL T2-weighted and contrast-enhanced T1-weighted images (P < .001). In the clinical study, IDEAL T2-weighted and contrast-enhanced T1-weighted images enabled significantly improved visualization of the dural sac (P < .001), spinal muscles (P < .05), uniformity of fat saturation (P < .001), and noise (P < .05). IDEAL T2-weighted and contrast-enhanced T1-weighted MR imaging examinations effectively reduce the degree of tissue-obscuring artifacts produced by spinal fixation hardware and improve image quality compared with FSFS T2-weighted and contrast-enhanced T1-weighted MR imaging. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101856/-/DC1.