Main applications of hybrid PET‐MRI contrast agents: a review

Abstract

In medical imaging, the continuous quest to improve diagnostic performance and optimize treatment strategies has led to the use of combined imaging modalities. Positron emission tomography (PET) and computed tomography (CT) is a hybrid imaging existing already for many years. The high spatial and contrast resolution of magnetic resonance imaging (MRI) and the high sensitivity and molecular information from PET imaging are leading to the development of this new hybrid imaging along with hybrid contrast agents. To create a hybrid contrast agent for PET-MRI device, a PET radiotracer needs to be combined with an MRI contrast agent. The most common approach is to add a radioactive isotope to the surface of a small superparamagnetic iron oxide (SPIO) particle. The resulting agents offer a wide range of applications, such as pH variation monitoring, non-invasive angiography and early imaging diagnosis of atherosclerosis. Oncology is the most promising field with the detection of sentinel lymph nodes and the targeting of tumor neoangiogenesis. Oncology and cardiovascular imaging are thus major areas of development for hybrid PET-MRI imaging systems and hybrid contrast agents. The aim is to combine high spatial resolution, high sensitivity, morphological and functional information. Future prospects include the use of specific antibodies and hybrid multimodal PET-MRI-ultrasound-fluorescence imaging with the potential to provide overall pre-, intra- and postoperative patient care.

Simultaneous in vivo PET/MRI using fluorine-18 labeled Fe3O4@Al(OH)3 nanoparticles: comparison of nanoparticle and nanoparticle-labeled stem cell distribution

“…Overcoming disadvantages of single modality imaging may also require the use of dual contrast agents in multimodal approaches, e.g., simultaneously acquired PET/MRI. Combining PET and MRI not only provides anatomical images with great soft tissue contrast (MRI), but also highly sensitive and specific functional, cellular (PET and MRI), and molecular images with low background (PET) depending on the radiotracer used [25,26]. While the time period that a tracer can be followed in vivo using PET is restricted and depends on the radionuclide's half-life, MRI allows long-term detection of dual contrast agents.…”

Multimodal Magnetic-Plasmonic Nanoparticles for Biomedical Applications

“…Importantly, all of these steps and processes can be monitored by MRI, CT (computed tomography) and other imaging techniques potentially allowing full control over the medical procedures [10][11][12]. New multimodal magnetic nanostructures have also found applications in molecular-imaging [13,14], as PET-MRI (positron emission tomography-magnetic resonance imaging) contrast agents [15], thermal therapy [16,17] targeted drug delivery and many others [18]. Our review will focus only of the recent developments of magnetic-plasmonic nanocomposites and their biological applications.…”

Novel therapeutic targets for cancer metastasis

“…Conventional imaging technologies used for detection, diagnosis, triaging and prognosis of organ cancers and tumor metastasis include ultrasound (US) and computed tomography (CT) [55,56]. However, because these tools lack the fine resolution to image small primary lesions at the microscopic level, researchers use other methods such as spinning disk confocal fluorescence microscopy, magnetic resonance imaging (MRI), positron emission tomography (PET) and MRI-PET hybrids [57]. These are noninvasive, in vivo imaging tools that use either radioisotopes, contrasting agents, or a combination radiolabelledcontrast agent to generate bright images with high sensitivity [12,[56][57][58][59].…”