Results
Overall, artifacts were larger on 3T than 1.5T and sequence-reliant. Artifacts were most pronounced on DWI and FL_3D sequences, least pronounced on T2 TIRM with TV and BU producing largest artifacts across all sequences.
Artifact size ranged from 5.7mm x 8.5 mm to 13.4mm x 17.7mm (area between 40.3mm2 to 188mm2) at 1.5T and 6.6mm x 8.2mm to 17.7mm x 20.7mm (area between 45.3mm2 to 306mm2) at 3T. The intra-rater agreement for the obtained artifact was high, with an ICC for the artifact area of 94.8% (95% CI: 89.1 – 97.2%), for the transversal extent of the artifact of 94.5% (95% CI: 87.1 – 97.2%) and for the longitudinal extent of 90.7% (95% CI: 85% - 94.3%). The reproducibility of the artifact size between repeated acquisitions of the same phantoms was between 70.0% and 91.4%. Inter-rater agreement for the artifact area was 85.7% (95% CI: 69.9 – 92.5%), 90.6% (95% CI: 84.8 – 94.2%) for the longitudinal extent and 80.4% (95% CI: 55.2 – 90.2%) for the transversal extent.
For a detailed overview of artifact sizes, please refer to Figs. 3, 4 and 5.
Fig 3: Comparison of artifact area between 1.5T and 3T for the different clips and sequences. For the shown boxplots, data of all measurements for each clip and field strength were pooled. Measurements at 1.5T and 3T were always performed at the same day. The results of these individual measurements are indicated as blue circles. Same day measurements are connected as dotted lines.
Fig 4: Comparison of artifact area between 1.5T and 3T for the different clips and diffusion sequences. For the shown boxplots, data of all measurements for each clip and field strength were pooled. Measurements at 1.5T and 3T were always performed at the same day. The results of these individual measurements are indicated as blue circles. Same day measurements are connected as dotted lines.
Fig 5: Comparison of artifact area between DWI and ADC images for the different clips. For the shown boxplots, data of all measurements for each clip and field strength were pooled. Measurements at 1.5T and 3T were always performed at the same day. The results of these individual measurements are indicated as blue circles. Same day measurements are connected as dotted lines.
