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[SPIO-enhanced MR angiography for the detection of venous thrombi in an animal model]
S A Schmitz1, J Hansel, S Wagner
1Abteilung für Radiologische Diagnostik, Universitäts-Klinikum Benjamin Franklin, Freie Universität Berlin. s.schmitz@medizin.fu-berlin.de
Purpose:
An animal model is used to investigate whether MR angiography combined with super-paramagnetic particles of iron oxide (SPIO) is suitable for detecting thromboses.
Methods:
42 rats in groups of 7 each were examined on days 1, 3, 5, 7, 9 and 11, respectively, after mechanical/chemical thrombus induction in a 1.5 Tesla magnet with a FISP sequence (TR/TE/FA 50 ms/6 ms/40 degrees). Imaging was performed before and up to 90 minutes after intravenous injection of 30 mumol FE/kg BW of the experimental SPIO (hydrodynamic diameter, 34 +/- 17 nm LLS; R1 and R2 relaxivity at 0.47 T, 31 and 57 L/(mmol*s)). MIP reconstructions of MR angiographies were submitted to consensus assessment by two examiners. using histology as the gold standard.
Results:
The image quality of MIP reconstructions was rated as good in 38 of 42 cases. With regard to thrombotic vessel occlusion, MR angiography coincided with histology in 17 of 42 cases and differed in 25, lumen narrowing being overestimated by MRI in 4 cases and underestimated in 21. In these 21 cases, the histologically observed recanalization could not be detected by MR angiography.
Conclusions:
SPIO-enhanced MR angiography achieves adequate vessel contrast and reliable thrombus detection in animal experiments. Partial volume effects prevent microscopically observed recanalization from being detected by clinical MRI.
Insights
Super-paramagnetic particles of iron oxide (SPIO)-enhanced MR angiography shows promise for detecting thromboses in animal models. However, it may miss microscopic recanalization due to partial volume effects.
Area of Science:
- Biomedical Imaging
- Vascular Biology
- Radiology
Background:
- Thrombosis detection remains a clinical challenge.
- Super-paramagnetic particles of iron oxide (SPIO) offer enhanced contrast in MRI.
- MR angiography (MRA) is a non-invasive imaging technique.
Purpose of the Study:
- To evaluate the efficacy of SPIO-enhanced MRA in detecting thromboses.
- To assess the suitability of this technique in an animal model.
Main Methods:
- A rat model with induced thrombi was used.
- Imaging was performed using a 1.5 Tesla MRI scanner with a FISP sequence.
- MR angiographies were acquired before and after SPIO injection, with histology as the gold standard.
Main Results:
- MIP reconstructions of MRA showed good image quality in most cases.
- MRA accurately detected thrombotic vessel occlusion in 17 out of 42 cases.
- MRA underestimated lumen narrowing in 21 cases, failing to detect histologically confirmed recanalization.
Conclusions:
- SPIO-enhanced MRA provides adequate vessel contrast and reliable thrombus detection in animal studies.
- Partial volume effects in clinical MRI can limit the detection of microscopic recanalization.