Superparamagnetic iron oxide-enhanced low-field MRI of liver tumors.

Abstract

Background: The advantages of low-field MRI are that there is little image
distortion, specific absorption rate can be kept low, and electron return effect
can be suppressed, so it can be used not only for interventional radiology, but
also for radiation therapy. The purpose of this study was to investigate the
visibility of superparamagnetic iron oxides (SPIO)-enhanced low-field MRI for
hepatic malignancy.
Materials and Methods: We retrospectively extracted 15 hepatic tumors from
10 patients who underwent SPIO-enhanced MRI at both 0.2T and 1.5T for MRI-
guided biopsy or radiofrequency ablation. Tumor-to-liver (T/L) signal intensity
ratio (SIR), as well as the SIRs of the aorta-to-background (A/B) and the spleen-
to-background (S/B) were calculated and compared between 0.2T and 1.5T
MRI using 2D fast low angle shot sequence.
Results: The mean values of T/L SIRs at 0.2T and 1.5T were 4.04 ± 1.96 and
5.08 ± 2.19 (mean ± standard deviation [SD]), respectively (p = 0.18). The mean
values of A/B SIRs at 0.2T and 1.5T were 174.70 ± 42.89 and 380.36 ±139.18
(mean ± SD), respectively (p < 0.01). The mean values of S/B SIRs at 0.2T and
1.5T were 93.58 ±48.13 and 197.28 ± 96.96 (mean ± SD), respectively (p <
0.01).
Conclusion: Malignant tumors of the liver were clearly visualized on 0.2T low-
field MRI after SPIO administration and are comparable to 1.5T high-field MRI.