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Abdominal MR angiography performed using blood pool contrast agents: comparison of a new superparamagnetic iron oxide
C Nolte-Ernsting1, G Adam, A Bücker
1Department of Diagnostic Radiology, University of Technology, Aachen, Germany.
Objective:
We evaluated and compared two different experimental blood pool contrast agents for abdominal MR angiography in an animal model.
Materials And Methods:
In seven pigs, coronal T1-weighted three-dimensional fast field-echo images were obtained on a conventional 1.5-T MR imaging system before and after i.v. injection of the ultrasmall superparamagnetic iron oxide agent FeO-BPA. In another seven pigs, MR angiograms were acquired using the gadolinium polymer WIN 22181. Enhanced images were obtained 5-210 min after injection of FeO-BPA and 1-120 min after injection of WIN 22181.
Results:
Both blood pool agents yielded detailed angiograms of the abdominal vascular tree when imaging lasted 2 min. In-plane running vessels were imaged without saturation effects and with equivalent maximum signal-to-noise ratios. Half the maximum signal-to-noise ratio was reached 150 min after injection of FeO-BPA, whereas this interval was approximately 70 min for the gadolinium polymer. Because of these different imaging half-life periods, the effective diagnostic window provided by FeO-BPA was six to eight times longer than that of WIN 22181. In the liver, the vascular T1 shortening and the parenchymal T2* effect of FeO-BPA complemented each other, resulting in an optimal contrast-to-noise ratio significantly higher than that achieved with WIN 22181. This "double-contrast effect" in the liver was especially helpful when obtaining detailed MR portograms.
Conclusion:
The blood pool agents FeO-BPA and WIN 22181 can be used to produce high-quality abdominal MR angiograms on standard MR imaging equipment. The contrast-to-noise ratio of hepatic vessels is best on iron oxide-enhanced images because of a T1-T2* synergistic effect in the liver. The longer diagnostic window provided by FeO-BPA coupled with the option of in-plane imaging suggests the usefulness of FeO-BPA in future MR imaging-guided vascular interventions.
Insights
Iron oxide (FeO-BPA) and gadolinium polymer (WIN 22181) agents provide detailed abdominal MR angiography. FeO-BPA offers a longer diagnostic window and superior liver imaging contrast for potential MR imaging-guided interventions.
Area of Science:
- Radiology
- Medical Imaging
- Vascular Imaging
Background:
- Blood pool contrast agents are crucial for Magnetic Resonance (MR) angiography.
- Evaluating novel agents is essential for improving diagnostic capabilities.
Purpose of the Study:
- To compare the efficacy of two experimental blood pool contrast agents, FeO-BPA (iron oxide) and WIN 22181 (gadolinium polymer), for abdominal MR angiography in an animal model.
- To assess image quality, diagnostic window, and contrast enhancement in the liver.
Main Methods:
- Coronal T1-weighted 3D fast field-echo MR images were acquired in pigs after intravenous injection of FeO-BPA or WIN 22181.
- Imaging was performed at various time points post-injection to evaluate dynamic contrast behavior.
- Signal-to-noise ratios and contrast-to-noise ratios were analyzed.
Main Results:
- Both agents produced detailed abdominal angiograms within a 2-minute imaging time.
- FeO-BPA demonstrated a significantly longer imaging half-life (150 min) compared to WIN 22181 (70 min), resulting in a 6-8 times longer diagnostic window.
- FeO-BPA achieved a superior contrast-to-noise ratio in the liver due to a synergistic T1-T2* effect, enhancing MR portography.
Conclusions:
- Both FeO-BPA and WIN 22181 are effective for high-quality abdominal MR angiography on standard equipment.
- FeO-BPA offers advantages for liver imaging and MR portography due to its T1-T2* synergistic effect.
- The extended diagnostic window and in-plane imaging capability of FeO-BPA suggest its utility in future MR imaging-guided vascular interventions.