Evaluation of unenhanced axial T1W and T2W liver MR images acquired from institutions within the Republic of Ireland and the Kingdom of Saudi Arabia.

INTRODUCTION

This multi-site study evaluated two breath-hold sequences commonly utilised for liver MRI; non-enhanced T1W-3D-FS-GRE-TRA and T2W-2D-FSE-TRA sequences, using physical measurements of SNR and CNR, and observer perceptions' (Visual Grading Analysis: VGA).

METHODS

Liver MR image datasets (n = 168) from nine hospitals in the Kingdom of Saudi Arabia (KSA) and 11 hospitals in the Republic of Ireland were evaluated. Images were categorised into two groups per sequence, defined by slice thickness (T2W-2D-FSE, ≤5 mm vs ≥ 6 mm and T1W-3D-GRE-FS, ≤3 mm vs 4 mm). Images were evaluated using visual grading analysis VGA and physical measurements: SNR/CNR. Account was taken of varying patient sizes based on AP/transverse diameter measurements.

RESULTS

Physical image quality measurements (SNR/CNR) returned no significant findings across Irish and KSA hospitals, for both sequences, despite variations in acquisition parameters. Statistically significant differences were found for some scoring criteria based on the observers' perceptions including spleen parenchyma, and spatial resolution for the non-enhanced T1W-3D-FS-GRE-TRA images, with a preference for images acquired using thin slices (≤3 mm). In addition, statistically significant difference was found for the scoring criteria motion artefact for the axial T2W-2D-FSE-TRA images, with a preference for images acquired using thick slices (≥5 mm). Negligible correlation was noted between SNR/CNR and measured abdominal AP/transverse diameters.

CONCLUSION

Whilst variations in sequences rendered no statistical differences in SNR/CNR findings, significant differences in observer image criteria scores was noted. The importance of both physical measurements and observers' perceptions evaluation methods for quality assessment of MR images was demonstrated and optimisation of liver sequence parameters is warranted.