Room: Exhibit Hall | Forum 8
Purpose: This study aims at identifying, classifying and measuring the frequency the different artifacts that show up in the images of the Sagittal T1 Fluid Attenuated Inversion Recovery (FLAIR) sequence.
Methods: 100 subjects underwent brain MRI examination, which was performed using a 1.5 Tesla MRI scanner. The following sequences were applied in every subject: Axial T1 Flair, Axial T2 weighted imaging, Diffusion Weighted Imaging, 2D Multiple Echo Recombined Gradient Echo, Sagittal T1 Flair, Coronal T2 Turbo Spin Echo, Spin Echo T1 weighted imaging and 3D Fast Spoiled Gradient-echo. In these images, we observed the following categories of artifacts: a) ghost artifacts, b1) aliasing behind the occipital bone, b2) aliasing inside the sphenoid cavity, c) susceptibility artifacts and d) pulsation artifacts. In order to recognize and verify the artifacts, we used not only the Sagittal T1 FLAIR sequence, but also sagittal reconstructions from the three-dimensional Fast Spoiled Gradient-echo sequence and all the other routine sequences.
Results: Aliasing artifacts and especially aliasing of nose are presented in 30% of the cases. In 45% of these cases the uncommon aliasing artifacts, which took place into the brain parenchyma (sphenoid cavity, subarachnoid bay or pituitary) originated from nose. In 15% of the subjects, ghost artifacts are presented, which stem from the nose, the orbits or other pulsating structures (pulsation artifacts) or even from fat tissue. Moreover, susceptibility artifacts comprise 10% of all the artifacts.
Conclusion: We suggest the application of Sagittal SE or TSE sequences in MRI examination of brain, trying to include the nose in the square of FOV. If we do not like to change the dimension of phase codification, we have to check very carefully the region of the sphenoid cavity and the parallel axis to insure that there are not aliasing artifacts, which are projected in the FOV.