Merging images with different central frequencies reduces banding artifacts in balanced steady-state free precession magnetic resonance cisternography.

PURPOSE

The aim of this study was to evaluate the utility of merged balanced steady-state free precession (bSSFP) magnetic resonance cisternography images.

MATERIALS AND METHODS

Twenty ears of 10 healthy volunteers (six men, four women; mean age ± standard deviation, 26.7 ± 1.6 yr) and 10 patients (two men, eight women; mean age, 46.3 ± 10.9 yr) with neoplasm around the sella turcica were included. Two different devices (A and B) were used to confirm the versatility of our method for MR devices with different local magnetic field homogeneity. Images with different central frequencies (±10, ±20, ±30, ±40, and ±50 Hz) were merged with the maximum magnitude of corresponding pixels from the images acquired using both devices. Two neuroradiologists visually graded the image quality of 11 sites in the inner ear and three sites around the sella turcica (scale: 0-2) and compared the quality with that of the corresponding basic image (0 Hz).

RESULTS

The image quality was better in merged images of the vestibule, superior semicircular canal (SCC), posterior SCC, and horizontal SCC (P = 0.005 to 0.020 mainly at ±40 and ±50 Hz on devices A and B), as well as in merged images of the sella turcica and right cavernous sinus (±50 Hz, P = 0.003 and 0.020 on device B, respectively), than it was in the corresponding basic images.

CONCLUSIONS

The maximum magnitude merging of images with different central frequencies makes it possible to reduce banding artifacts on bSSFP images without the need for special pulse sequences and image processing programs.