Reducing metallic artefacts in post-operative spinal imaging: slice encoding for metal artefact correction with dual-source parallel radiofrequency excitation MRI at 3.0 T

Abstract

To compare the effects of metal artefacts and acquisition time among slice encoding for metal artefact correction (SEMAC), SEMAC with dual-source parallel radiofrequency (SEMAC-DSPRF) transmission and fast spin echo (FSE) images using 3.0-T MRI. The signal-to-noise ratio (SNR) was calculated in a phantom study using a pedicle screw. A total of 16 patients who underwent spinal surgery using pedicle screws were included in the clinical study. T1 weighted FSE, SEMAC and SEMAC-DSPRF images were obtained. Four imaging findings (visibility of the dural sac, neural foramens, bone-implant interface and overall artefacts) were evaluated by using five-point scales independently by two observers. The mean scan time was recorded. The mean SNR was 71.2, 25.7 and 28.4 for FSE, SEMAC and SEMAC-DSPRF images, respectively. FSE images were ranked lower than SEMAC and SEMAC-DSPRF images, and ranking of SEMAC and SEMAC-DSPRF images did not differ statistically for all four imaging findings. The mean scan time was 9 min 51 s and 6 min 31 s for SEMAC and SEMAC-DSPRF images, respectively. SEMAC can reduce metallic artefacts and improve the visualisation of anatomical structures around metal implants. An additional DSPRF technique can reduce the acquisition time of SEMAC images without the loss of SNR and image quality. This study demonstrates that the use of the DSPRF transmission technique can reduce the acquisition time of SEMAC images without loss of image quality in patients with metal implants.