Quantification of magnetic nanocomposites through cross-calibration of MR and X-ray imaging.
Measurement Systems
Final Report Abstract
A preliminary study of a long-term phantom for MRI and X-Ray imaging of body tissues enriched with magnetic nanocomposites has shown that PG is suitable for 3-dimensional and quantitative imaging of tissues after, for example, magnetically assisted cancer treatments. These phantoms consist of an elastomer with different concentrations of multi-core magnetic nanocomposites. For this a novel matrix material has been tested to embed magnetic composites and consequently create a long-term stable phantom for biological tissue enriched with magnetic composites for XCT and MRI. This tissue substitute material is a synthetic thermoplastic (PermaGel=PG), which is stable at room temperature over several years. The main purpose of this material based on white mineral oil is to serve for ballistic experiments. But in the presented first trial it has been found as an acceptable phantom system for XCT and MRI examination. It was possible to suspend a particular biocompatible magnetic nanocomposite in PG; thereby magnetite concentrations from 0 mg/ml to 6.91 mg/ml were reached. The created phantom is a stack of three PG-MNC-cylinders which are separated by blank PG. The resulting phantom was examined with several measuring techniques to understand their behaviour and test their suitability as a long-term phantom for XCT and MRI. The phantoms were examined with NMR relaxometer Bruker minispec mq 60 to obtain R1 and R2 relaxation rates; with SQUID and chemical digestion with a subsequent ICP-MS to verify the magnetic component content and visualised 3-dimensionaly with XµCT and 9.4 T MRI. R2 values from NMR-Relaxometry had shown a strong linear correlation (R = 0.994) with magnetite concentrations between 0 mg/ml up to 4.5 mg/ml. For the XµCT-apparatus, a sensitivity range from 0.723 mg/ml to 6.91 mg/ml has been found. For MRI, both the SSE and MSME data produced strong linear correlations (R = 0.990 and 0.991, respectively) over magnetite concentrations between 0 and 1.435 mg/ml. As expected, high-field MRI has better sensitivity for nanoparticles with low to moderate magnetite concentrations, while XµCT performs best with moderate to high magnetite concentrations. The common detection range of 9.4 T MRI and XµCT for magnetite in these PG and PG-MNC phantoms lies between 0.723 mg/ml and 1.435 mg/ml.
