Evaluating magnetic resonance brain images performed with 1.5T and 3T scanners, in a state general hospital in Malta

Abstract

Purpose: Magnetic resonance imaging (MRI) scanners with an increased field strength produce scans with an improved image quality, however this is limited by the presence of artefacts which tend to increase as well. The aim of this study was to evaluate the image quality of scans obtained with a 1.5T and 3T scanners, in a state general hospital in Malta. Objectives The first objective was to statistically compare the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), on all sequences included in the local routine MR brain scanning protocol, for a 1.5T and 3T scanner (phase 1). The second objective was to review the image quality of scans of certain sequences, based on the results of phase 1 (phase 2). Methodology: This study adopted a prospective, cross-sectional, quantitative and a nonexperimental research design. Ten normal MRI brain scans taken on each scanner, were included. For phase 1, the SNR and CNR for each sequence, of each brain scan, were calculated and analysed statistically. Based on these results, the Axial T2 weighted (W) and fluid low attenuation inversion recovery (FLAIR) sequences were chosen to be reviewed in phase 2 by two radiologists, using visual grading analysis (VGA). The presence of artefacts was also assessed. Results: Results from phase 1 indicated that SNR and CNR on scans produced by the 3T scanner were superior, with the exception of the CNR of the 3DT1W sequence. Statistical significant results were obtained for the Axial T2W and FLAIR sequences (p<0.05). Results from phase 2 indicated that for the VGA section, 3T scanner was superior to the 1.5T scanner (AUC>0.5). Artefacts were potentially more common on the 1.5T scanner, however the statistical difference was not significant overall (p>0.05). Conclusions: The results obtained from both phases of this study indicated that the 3T scanner has a superior image quality when compared to the 1.5T scanner. The potential increase in artefacts on the 1.5T scanner contradicted the majority of the reviewed literature, however the difference was still not significant.