Magnetic nanoparticle imaging by means of minimum norm estimates from remanence measurements.
In magnetic nanoparticle imaging, magnetic nanoparticles are coated and functionalized to bind to specific targets. After measuring their magnetic relaxation or remanence, their distribution can be determined by means of inverse methods. The reconstruction algorithm presented in this paper includes first a dipole fit using a Levenberg-Marquardt optimizer to determine the reconstruction plane. Secondly, a minimum norm estimate is obtained on a regular grid placed in that plane. Computer simulations involving different parameter sets and conditions show that the used approach allows for the reconstruction of distributed sources, although the reconstructed shapes are distorted by blurring effects. The reconstruction quality depends on the signal-to-noise ratio of the measurements and decreases with larger sensor-source distances and higher grid spacings. In phantom measurements, the magnetic remanence of nanoparticle columns with clinical relevant sizes is determined with two common measurement systems. The reconstructions from these measurements indicate that the approach is applicable for clinical measurements. Our results provide parameter sets for successful application of minimum norm approaches to Magnetic Nanoparticle Imaging.
Baumgarten
Daniel
D
Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, P.O. Box 100565, 98684 Ilmenau, Germany. daniel.baumgarten@tu-ilmenau.de
Liehr
Mario
M
Wiekhorst
Frank
F
Steinhoff
Uwe
U
Münster
Peter
P
Miethe
Peter
P
Trahms
Lutz
L
Haueisen
Jens
J
D000465:Algorithms; D003198:Computer Simulation; D004568:Electrodiagnosis / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008280:Magnetics / Q000379:methods*; D053758:Nanoparticles; D019047:Phantoms, Imaging