Evaluation of metal artifacts in clinical MR images of patients with total hip arthroplasty using different metal artifact-reducing sequences
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To evaluate the distortion and artifact area of metal in MR images and to compare artifact reduction using different metal artifact-reducing sequences in patients with metal-on-metal (MoM) and non-MoM total hip prostheses.
Materials and methods
Thirty-six MoM and 15 non-MoM prostheses were examined in a 1.5-T MR scanner using T1-weighted (T1-w) sequences: turbo spin echo (TSE) high-readout bandwidth (hiBW), T1-w; TSE view angle tilting (VAT), T1-w; TSE VAT + slice encoding for metal artifact correction (SEMAC); short tau inversion recovery (STIR) hiBW or matched RF pulses (mRFp). Distortion was quantified using a new method measuring the acetabular roof angle (ARA). The artifact area was defined in the mid-coronal plane of the artifact.
The T1 VAT + SEMAC sequence showed the least distortion compared to T1 VAT and T1-hiBW (150°, 127° and 102°, p < 0.001, in MoM; 152°, 143° and 128°, p ≤ 0.014, in non-MoM). The artifact area was smaller in MoM prostheses using the T1 VAT sequence compared to T1 hiBW and T1 VAT + SEMAC (2506 mm2, 3160 mm2 and 3214 mm2, p < 0.001) and smaller in non-MoM prostheses using T1 VAT compared to T1-hiBW (4296 mm2 and 4831 mm2, p = 0.041). STIR-mRFp substantially reduced the artifact size compared with STIR-hiBW (MoM 4559 mm2 and 6323 mm2; non-MoM 5625 mm2 and 8764 mm2, p < 0.001).
Metal artifacts in MR imaging examinations of hip prostheses can be evaluated for distortion using a distortion angle (ARA) and the degree of signal artifact as determined by measuring the largest cross-sectional artifact area. T1 VAT + SEMAC showed the least distortion; T1 VAT and STIR-mRFp were most efficient for reduction of the artifact area.
KeywordsMR imaging Metal artifact-reducing sequences (MARS) Metal artifact Hip Hip prosthesis Artifact measurement Image distortion
Conflicts of interest
None of the authors has a financial interest.