  The use of engineered nanoscale magnetic materials in healthcare and
biomedical technologies is rapidly growing. Two examples which have recently
attracted significant attention are magnetic particle imaging (MPI) for
biological monitoring, and magnetic field hyperthermia (MFH) for cancer
therapy. Here for the first time, the capability of a Lissajous scanning MPI
device to act as a standalone platform to support the application of MFH cancer
treatment is presented. The platform is shown to offer functionalities for
nanoparticle localization, focused hyperthermia therapy application, and
non-invasive tissue thermometry in one device. Combined, these capabilities
have the potential to significantly enhance the accuracy, effectiveness and
safety of MFH therapy. Measurements of nanoparticle hyperthermia during
protracted exposure to the MPI scanner's 3D imaging field sequence revealed
spatially focused heating, with a maximum that is significantly enhanced
compared with a simple 1-dimensional sinusoidal excitation. The observed
spatial heating behavior is qualitatively described based on a phenomenological
model considering torques exerted in the Brownian regime. In-vitro cell studies
using a human acute monocytic leukemia cell line (THP-1) demonstrated strong
suppression of both structural integrity and metabolic activity within 24 h
following a 40 min MFH treatment actuated within the Lissajous MPI scanner.
Furthermore, reconstructed MPI images of the nanoparticles distributed among
the cells, and the temperature-sensitivity of the MPI imaging signal obtained
during treatment are demonstrated. In summary, combined Lissajous MPI and MFH
technologies are presented; demonstrating for the first time their potential
for cancer treatment with maximum effectiveness, and minimal collateral damage
to surrounding tissues.
