Radiolabeled PET/MRI Nanoparticles for Tumor Imaging

Abstract

The development of integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) scanners opened a new scenario for cancer diagnosis, treatment, and follow-up. Multimodal imaging combines functional and morphological information from different modalities, which, singularly, cannot provide a comprehensive pathophysiological overview. Molecular imaging exploits multimodal imaging in order to obtain information at a biological and cellular level; in this way, it is possible to track biological pathways and discover many typical tumoral features. In this context, nanoparticle-based contrast agents (CAs) can improve probe biocompatibility and biodistribution, prolonging blood half-life to achieve specific target accumulation and non-toxicity. In addition, CAs can be simultaneously delivered with drugs or, in general, therapeutic agents gathering a dual diagnostic and therapeutic effect in order to perform cancer diagnosis and treatment simultaneous. The way for personalized medicine is not so far. Herein, we report principles, characteristics, applications, and concerns of nanoparticle (NP)-based PET/MRI CAs. modality allows gathering all the necessary morphological and functional information, the combination of two or more imaging techniques, also called multimodal imaging or hybrid imaging, can offer synergistic advantages over any modality alone [11], overcoming its drawbacks and strengthening the peculiarities. The traditional approach was directed to the integration of a structural imaging modality (CT, MRI) with a functional highly sensitive imaging modality (PET/SPECT). Thus, firstly, PET/CT and SPECT/CT were introduced in clinical settings. The first PET/CT scanner was developed in 1998 by Townsend and colleagues [12] and was commercialized in 2001. It consists of a PET component independent from CT, and a single bed moves axially into the scanner while the patient sequentially performs CT and PET scans [13]. To date, PET/CT scanners completely replaced standalone PET scanners [14], exploiting anatomical reference and attenuation estimation from CT data. The success of PET/CT scanners inspired the feasibility of a PET/MRI scanner [15]. Three different configuration options were developed over the years [16]: the first consists of a sequential acquisition, similarly to PET/CT, where the patient undergoes firstly a MRI scan and later a PET scan; even if the MRI and PET components must be minimally modified, two consecutive acquisitions are performed without simultaneity. Temporal mismatches between PET metabolic data and MRI morphological information such as patient motion are the main weak points [7]. Nearly 15 years ago, some researchers working in preclinical settings analyzed the possibility of integrating a modified PET scanner into an MRI system. In Tubingen, Germany, an MRI-compatible PET scanner was inserted into a 3T clinical MRI scanner [8]; this system is suitable for preclinical studies or human brain imaging. The third option considers a first fully integrated whole-body PET/MRI sys...

Imaging techniques in nanomedical research

“…In the last decades, in vivo imaging devices have become fundamental tools in basic sciences, in preclinical research and in modern drug development to visualize nanocomposites. The most suitable and commonly used techniques are magnetic resonance imaging (MRI), optical imaging (OI), positron emission tomography (PET), 15 computed tomography and ultrasonography, 16 and a number of recent articles focused on the visualization of nanoconstructs by these approaches in a biological environment.…”

Theranostic cancer applications utilized by nanoparticles offering multimodal systems and future insights

“…Nanoparticle-based cancer diagnostics employ various instrumental techniques utilizing optical, magnetic, radioactive and acoustic properties of carrier or contrast agent nanoparticles [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. These particles either have those properties intrinsically (material and shape dependent) or carry those molecules or other nanoparticles that embody them.…”

“…fluorodeoxyglucose) alone, they can be entrapped in a nanoparticle system so that this complex can be used as a more powerful contrast agent for Positron Emission Tomography (PET) where the signal intensities are enhanced by localizing more radioactive tracer molecules [15]. It is also possible that hybrid particle systems loaded with active tracer molecules can offer multimodal imaging systems such as PET/MRI [15][16][17]. Also, nanoparticles can be used as contrast agents for Computed Tomography (CT or CAT scan) imaging due to their strong X-ray attenuation that lead them to be displayed as bright images [26].…”

Preclinical Models: Boosting Synergies for Improved Translation

“…They also detail the genetic drift that these cells underwent as an adaptive response to in vitro and in vivo expansion. Cancer, and more specifically the usage of nanoparticles (NP) both for multimodal imaging and as contrast agents (CAs), is the topic of a review [8] which highlights the advantages of using NP-based PET/MRI multimodal imaging in tumor diagnosis and characterization. Additionally, these nanosystems can be applied to theranostics in the very prominent scenario of personalized medicine.…”

“…Good news from the field of skin regeneration: the work on bioengineered skin substitutes has been selected by the editorial board as the cover story of the issue of December 2019 (www.mdpi.com/2077-0383/8/12). The article, presented by a group active in the field of dermal substitutes [13] and three-dimensional tissue-like models [14], is focused on the analysis of the most Cancer, and more specifically the usage of nanoparticles (NP) both for multimodal imaging and as contrast agents (CAs), is the topic of a review [8] which highlights the advantages of using NP-based PET/MRI multimodal imaging in tumor diagnosis and characterization. Additionally, these nanosystems can be applied to theranostics in the very prominent scenario of personalized medicine.…”