Progress in atherosclerotic plaque imaging

Cardiovascular diseases are the primary cause of mortality in the industrialized world,and arterial obstruction, triggered by rupture-prone atherosclerotic plaques,lead to myocardial infarction and cerebral stroke.Vulnerable plaques do not necessarily occur with flow-limiting stenosis,thus conventional luminographic assessment of the pathology fails to identify unstable lesions.In this review we discuss the currently available imaging modalities used to investigate morphological features and biological characteristics of the atherosclerotic plaque. The different imaging modalities such as ultrasound, magnetic resonance imaging,computed tomography, nuclear imaging and their intravascular applications are illustrated,highlighting their specific diagnostic potential.Clinically available and upcoming methodologies are also reviewed along with the related challenges in their clinical translation,concerning the specific invasiveness, accuracy and cost-effectiveness of these methods.

Magnetically-coated silica nanospheres for dual-mode imaging at low ultrasound frequency

AIM: To experimentally investigate the acoustical behavior of different dual-mode nanosized contrast agents(NPCAs) for echographic medical imaging at low ultrasound(US) frequency. METHODS: We synthesized three different nanosized structures:(1) Pure silica nanospheres(SiNSs);(2) FePt-iron oxide(FePt-IO)-coated SiNSs; and(3) IOcoated SiNSs, employing three different diameter of SiNS-core(160, 330 and 660 nm). Tissue mimicking phantoms made of agarose gel solution containing 5 mg of different NPCAs in 2 mL-Eppendorf tubes, were insonified by a commercial echographic system at three different low US pulse values(2.5, 3.5 and 4.5 MHz). The raw radiofrequency signal, backscattered from each considered NPCA containing sample, has been processed in order to calculate the US average backscatter intensity and compare the acoustic behavior of the different NPCA types. RESULTS: The highest US contrast was exhibited by pure SiNSs; FePt-IO-coated SiNSs acoustical behavior followed a similar trend of pure SiNSs with a slight difference in terms of brightness values. The acoustic response of the examined NPCAs resulted function of both SiNS diameter and US frequency. Specifically, higher US frequencies determined higher value of the backscatter for a given SiNS diameter. Frequencydependent enhancement was marked for pure SiNSs and became less remarkable for FePt-IO-coated SiNSs, whereas IO-coated SiNSs resulted almost unaffected by such frequency variations. Pure and FePt-IO-coated SiNSs evidenced an image backscatter increasing with the diameter up to 330 nm. Conversely, among the types of NPCA tested, IO-coated SiNSs showed the lowest acoustical response for each synthesized diameter and employed US frequency, although a diameter-dependent raising trend was evidenced. CONCLUSION: The US characterization of magnetically covered SiNS shows that FePt-IO, rather than IO, was the best magnetic coating for realizing NPCAs suitable for dual mode imaging of deep organs, combining US and magnetic resonance imaging.

Echographic imaging of tumoral cells through novel nanosystems for image diagnosis

Since the recognition of disease molecular basis,it has become clear that the keystone moments of medical practice,namely early diagnosis,appropriate therapeutic treatment and patient follow-up,must be approached at a molecular level.These objectives will be in the near future more effectively achievable thanks to the impressive developments in nanotechnologies and their applications to the biomedical field,starting-up the nanomedicine era.The continuous advances in the development of biocompatible smart nanomaterials,in particular,will be crucial in several aspects of medicine.In fact,the possibility of manufacturing nanoparticle contrast agents that can be selectively targeted to specific pathological cells has extended molecular im-aging applications to non-ionizing techniques and,at the same time,has made reachable the perspective of combining highly accurate diagnoses and personalized therapies in a single theranostic intervention.Main developing applications of nanosized theranostic agents include targeted molecular imaging,controlled drug release,therapeutic monitoring,guidance of radiationbased treatments and surgical interventions.Here we will review the most recent findings in nanoparticles contrast agents and their applications in the field of cancer molecular imaging employing non-ionizing techniques and disease-specific contrast agents,with special focus on recent findings on those nanomaterials particularly promising for ultrasound molecular imaging and simultaneous treatment of cancer.