http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120424/-/DC1.

Magnetic particle imaging has emerged as a new technique for the visualization and quantification of superparamagnetic iron oxide nanoparticles. It seems to be a very promising application for cardiovascular interventional radiology. A prerequisite for interventions is the artifact-free visualization of the required instruments and implants. Various commercially available catheters, guide wires, and a catheter experimentally coated with superparamagnetic iron oxide nanoparticles were tested regarding their signal characteristics using magnetic particle spectroscopy to evaluate their performance in magnetic particle imaging. The results indicate that signal-generating and non-signal-generating instruments can be distinguished. Furthermore, coating or loading non-signal-generating instruments with superparamagnetic iron oxide nanoparticles seems to be a promising approach, but optimized nanoparticles need yet to be developed.

No abstract

Purpose:To quantify the B1-field induced tissue warming on a 3T-whole-body scanner, to test whether the patient is able to sense the temperature change, and to evaluate whether the imaging procedure constitutes a significant cardiovascular stress. Materials and Methods:A total of 18 volunteers were divided into three equal groups for 3.0T MRI of the pelvis, the head, or the knee. An imaging protocol operating at first level mode was applied, allowing radio frequency (RF) irradiation up to the legal specific absorption rate (SAR) limits. An identical placebo protocol with active gradient switching but without RF transmission was used. Temperature changes were measured with a fiber-optic thermometer (FO) and an infrared camera (IR).Results: Temperature differences to the placebo were highest for imaging of the pelvis (FO: ⌬T ϭ 0.88 Ϯ 0.13°C, IR: ⌬T ϭ 1.01 Ϯ 0.15°C) as compared to the head (FO: ⌬T ϭ 0.46 Ϯ 0.12°C, IR: ⌬T ϭ 0.47 Ϯ 0.10°C) and the knee (FO: ⌬T ϭ 0.33 Ϯ 0.11°C, IR: ⌬T ϭ 0.37 Ϯ 0.09°C). The volunteers were able to discriminate between imaging and placebo for pelvic (P Ͻ 0.0001) and head (P ϭ 0.0005) imaging but not for knee imaging (P ϭ 0.209). No changes in heart rate or blood pressure were detected. Conclusion:The 3.0T MRI in the first operational mode may lead to measurable and perceptible thermal energy deposition. However, it may be regarded as safe concerning the thermoregulatory cardiovascular stress.

Magnetic particle imaging (MPI) has emerged as a new imaging method with the potential of delivering images of high spatial and temporal resolutions and free of ionizing radiation. Recent studies demonstrated the feasibility of differentiation between signal-generating and non-signal-generating devices in Magnetic Particle Spectroscopy (MPS) and visualization of commercially available catheters and guide-wires in MPI itself. Thus, MPI seems to be a promising imaging tool for cardiovascular interventions. Several commercially available catheters and guide-wires were tested in this study regarding heating. Heating behavior was correlated to the spectra generated by the devices and measured by the MPI. The results indicate that each instrument should be tested separately due to the wide spectrum of measured temperature changes of signal-generating instruments, which is up to 85°C in contrast to non-signal-generating devices. Development of higher temperatures seems to be a limitation for the use of these devices in cardiovascular interventions.