5 research outputs found
Analysis of the hyperthermia efficiency and MRI quality trade off in PMMA-based bone cements loaded with magnetic nanoparticles
No full textSummary form only given. In this work, T 1 -weighted images (MP-RAGE sequence) of cylindrical PMMA mixed with MNP (PMMA-MNP) samples have been carried out in agar gel phantoms with a Siemens 3T MR scanner. Two types of MNP were tested (iron oxide powder and ferrofluid suspension) with different concentrations. For every MRI session, 21 slices were selected centralized around the half length of the sample. The artifact caused by the magnetic nanoparticles was measured in each slice by fitting an ellipse to the disturbed area and subtracting the radius of the sample from the average of the major and minor ellipse radii. As a tool for the fitting, the images were masked with a threshold of 30% of their maximal value. Since each phantom was measured twice, this procedure led to a total of 42 values, indicating the spread of the artifact, for each MNP concentration. Boxplots of the measured artifact as function of MNP concentrations were depicted. Ferrofluid samples give rise to lower MRI artifacts compared to samples prepared with the iron oxide powder and having the same MNP concentration. Moreover, the values vary less between the slices for ferrofluid samples as can be seen by smaller interquartile ranges. Results demonstrate that both concentration and type of MNP affect the MRI behavior of PMMA-MNP samples. In this study, we provide a balance of the needed MNP concentration to have an efficient magnetic hyperthermia treatment with minimum artifact for the required quality of MRI in case of PMMA-based bone cements loaded with MNP
Experimental ex-vivo validation of PMMA-based bone cements loaded with magnetic nanoparticles enabling hyperthermia of metastatic bone tumors
No full textPercutaneous vertebroplasty comprises the injection of Polymethylmethacrylate (PMMA) bone cement into vertebrae and can be used for the treatment of compression fractures of vertebrae. Metastatic bone tumors can cause such compression fractures but are not treated when injecting PMMA-based bone cement. Hyperthermia of tumors can on the other hand be attained by placing magnetic nanoparticles (MNPs) in an alternating magnetic field (AMF). Loading the PMMA-based bone cement with MNPs could both serve vertebra stabilization and metastatic bone tumor hyperthermia when subjecting this PMMA-MNP to an AMF. A dedicated pancake coil is designed with a self-inductance of 10 mu H in series with a capacitance of 0.1 mu F that acts as resonant inductor-capacitor circuit to generate the AMF. The thermal rise is appraised in beef vertebra placed at 10 cm from the AMF generating circuit using optical temperatures sensors, i. e. in the center of thePMMA-MNPbone cement, which is located in the vicinity of metastatic bone tumors in clinical applications; and in the spine, which needs to be safeguarded to high temperature exposures. Results show a temperature rise of about 7 degrees C in PMMA-MNP whereas the temperature rise in the spine remains limited to 1 degrees C. Moreover, multicycles heating of PMMA-MNP is experimentally verified, validating the technical feasibility of having PMMA-MNP as basic component for percutaneous vertebroplasty combined with hyperthermia treatment of metastatic bone tumors
