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MR lymphography with iron oxide particles: dose-response studies and pulse sequence optimization in rabbits
B Hamm1, M Taupitz, P Hussmann
1Department of Radiology, Klinikum Steglitz, Freie Universität Berlin, Germany.
AJR. American Journal of Roentgenology
|January 1, 1992
Summary
Superparamagnetic iron oxide (SPIO) particles optimize MR lymphography. Optimal contrast enhancement of normal lymph nodes with SPIO occurs at 0.2-1.0 mumol Fe using proton density-weighted spin-echo sequences.
Area of Science:
- Biomedical Imaging
- Nanotechnology
- Radiology
Background:
- Superparamagnetic iron oxide (SPIO) particles show potential as MR contrast agents for lymphography.
- Detailed investigations into SPIO's effect on normal lymph node MR imaging and optimal dosing are lacking.
Purpose of the Study:
- To investigate the dose-response relationship of SPIO in MR lymphography.
- To optimize pulse sequences for enhanced MR imaging of normal lymph nodes using SPIO.
Main Methods:
- MR imaging of rabbit iliac lymph nodes at 1.5 T using 12 spin-echo (SE) and gradient-echo (GRE) sequences.
- SPIO administered at five different doses (0.02-2.0 mumol Fe) via femoral lymph vessel injection.
- Determined the dose causing half maximal signal intensity reduction (ED50) and qualitative image assessment.
Main Results:
- Doses of 0.2-1.0 mumol Fe achieved complete signal loss in lymph nodes.
- Proton density-weighted SE sequences (ED50, 0.132 mumol Fe) provided sharp lymph node demarcation.
- GRE and T2-weighted SE sequences showed greater signal loss but poorer anatomic resolution.
- Underdosing resulted in focal signal loss; overdosing caused image distortion.
Conclusions:
- Optimal SPIO contrast enhancement for normal lymph nodes is achieved with doses of 0.2-1.0 mumol Fe.
- Proton density-weighted SE sequences are recommended for SPIO-enhanced MR lymphography.
- These findings provide a basis for developing noninvasive MR lymphography techniques.