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Detection of focal liver lesions with superparamagnetic iron oxide: value of STIR and SE imaging
J T Halavaara1, A E Lamminen, S Bondestam
1Department of Radiology, Helsinki University Central Hospital, Finland.
Objective:
We assessed the value of superparamagnetic iron oxide (SPIO) particles on the detection of focal liver lesions by MRI.
Materials And Methods:
Twenty patients with one to five focal liver lesions, primarily detected with ultrasonography and/or contrast-enhanced CT, were evaluated further with unenhanced and iron oxide-enhanced MRI at 1.0 T. Superparamagnetic iron oxide particles were administered intravenously as a slow infusion. Then T1-, T2-, and proton density-weighted SE images were obtained. In addition, the performance of a short TI inversion recovery (STIR) sequence was evaluated.
Results:
The iron oxide contrast medium had marked effects on liver signal-to-noise (S/N) and tumor-to-liver contrast-to-noise (C/N) ratios but only minimal effects on tumor S/N ratios in cases of malignant tumor foci. Lesion-to-liver contrast, expressed as differences between the tumor and liver S/N ratios, improved very significantly after SPIO infusion with all four pulse sequences. Contrast enhancement of the liver parenchyma was best in T2-weighted SE images, but the tumor-to-liver C/N values were highest with the postcontrast STIR sequence. The SPIO enhancement revealed a number of additional focal lesions (31%), also foci under 1 cm in diameter. In three benign focal lesions, SPIO infusion produced a definite reduction in the S/N ratio of the lesions in contrast to the minimal change measured in malignant foci. The favorable performance of the STIR sequence contradicts the disappointing results previously obtained at 0.6 T.
Conclusion:
Superparamagnetic iron oxide is a promising new contrast medium for MR examinations of the liver, increasing the conspicuity and reducing the detectability threshold of focal hepatic lesions.
Insights
Superparamagnetic iron oxide (SPIO) particles significantly improve MRI detection of liver lesions. SPIO enhanced lesion-to-liver contrast and revealed more small lesions, aiding diagnosis.
Area of Science:
- Radiology
- Medical Imaging
- Hepatology
Background:
- Focal liver lesions require accurate detection for diagnosis and management.
- Magnetic Resonance Imaging (MRI) is a key modality for liver lesion evaluation.
- Superparamagnetic iron oxide (SPIO) particles offer unique contrast properties for MRI.
Purpose of the Study:
- To evaluate the diagnostic value of superparamagnetic iron oxide (SPIO) particles in detecting focal liver lesions using MRI.
- To assess the impact of SPIO on signal-to-noise (S/N) and contrast-to-noise (C/N) ratios in liver lesions.
Main Methods:
- Twenty patients with focal liver lesions underwent unenhanced and SPIO-enhanced MRI at 1.0 T.
- SPIO particles were administered intravenously.
- T1-, T2-, proton density-weighted SE, and STIR sequences were evaluated.
Main Results:
- SPIO significantly improved lesion-to-liver contrast across all pulse sequences.
- The STIR sequence yielded the highest tumor-to-liver C/N values post-SPIO.
- SPIO revealed additional lesions (31%), particularly those under 1 cm.
- Benign lesions showed a marked S/N reduction, unlike malignant foci.
Conclusions:
- Superparamagnetic iron oxide (SPIO) is a valuable contrast agent for liver MRI.
- SPIO enhances lesion conspicuity and lowers the detection threshold for focal hepatic lesions.
- The STIR sequence demonstrates superior performance with SPIO at 1.0 T for liver lesion detection.