Biomedical Engineering Reference
In-Depth Information
tumor destruction of 24-342% volumetric increase (median 32%) compared to
a decrease of 76-88% for treated with RF alone.
236
In the combination ther-
apy group, increased diameter of the treatment effect for multiple tumor types,
improved completeness of tumor destruction particularly adjacent to intratu-
moral vessels, and increased treatment effect including the peritumoral liver
parenchyma (suggesting a contribution to achieving an adequate ablative mar-
gin) were observed.
7.6 NMS AS CONTRAST AGENTS
The recent advances in instrumentation and molecular profiling of diseases
have motivated the development of specific contrast agents to facilitate the non-
invasive detection and visualization of morphological and biochemical changes
that influence disease and/or its response to therapy.
3
The advances in this
area has been focused largely in oncology, from the identification of specific
molecular pathways associated with tumorigenesis to the clinical monitoring of
cancer biomarkers before and after treatment. The discovery and integration of
new and improved highly specific contrast agents with existing conventional as
well as upcoming diagnostic imaging techniques can have a major impact on
the detection, diagnosis, and decision making for personalized molecular-based
treatment.
Today, molecular specific imaging in the clinics is already in practice.
3
Magnetic resonance imaging (MRI), positron emission tomography (PET), and
single photon emission computed tomography (SPECT) are some of the first
clinical imaging modalities capable of generating images with molecular speci-
ficity.
3
These technologies take advantage of the use of different exogenously
administered contrast agents to monitor and collect information about tissue
anatomy, physiology, and metabolism. New improved and specific contrast
agents for these and other imaging techniques are continually being introduced
to enhance clinical care. Probably this century's most promising platform for
clinical imaging techniques are NMs which offer high contrast, tunable size,
shape, and surface properties, ease of integrating multiple functionalities, and
long circulation times.
237,238
Various NMs including superparamagnetic materi-
als, metal NPs, dendrimers, polymers, liposomes, and more are currently being
developed for a wide range of clinical indications. These different platforms
offer varying degrees in bioavailability, pharmacokinetics, toxicity, immunoge-
nicity, and specificity. Hence, it is more than likely that a variety of different and
specialized NMs platforms will be suited for targeting different diseases and
processes. A number of NMs based contrast agents are already in the market
and additional products are currently undergoing clinical testing or entering the
pipeline.
3
The nanoparticle-based contrast agents developments were initially focused
to compete with gadolium (Gd) based contrast agents for MRI.
3
Today, the SPI-
ONs based contrast agents are already in clinical use.
3
