Current status and future perspectives of PET/MRI hybrid imaging

Abstract

The success of hybrid PET/CT imaging over the last decade was mainly based on the complementary information it provided. The integration of a primarily morphologic technique such as CT with a functional modality like PET enabled the better and more accurate characterization and localization of in vivo processes. It appears therefore natural to believe that the recent development of combined PET/MRI devices would represent the next step in hybrid imaging by capturing the unique characteristics offered by MRI. By combining the exquisite anatomical and functional information offered by MRI with metabolic data from PET imaging, a new era of exciting new research and clinical possibilities seems to be unfolding.While the full scope of PET/MRI applications remains to be defined, the recent initial experience has shown advances in protocol design, image reconstruction, data processing, and image interpretation. Despite these promising results suggest that the medical community could now focus in an optimization and standardization of the patient workflow for developing new clinical indications, incomplete resolution of attenuation correction protocols and the search for the incremental value of PET/MRI when compared to the current standard of care PET/CT still need to be entirely sort out.This concurrent imaging protocol facilitates the MR acquisition of not only morphological information but also pathophysiological data. When combined with the biochemical, metabolic, and kinetic biodistribution changes provided by PET, this synergy of added functional information could surpass what PET/CT has currently to offer. Multiple efforts are underway to gather the required prospective instrumentation and clinical data to delineate the most cost-effective applications of this new technology. The available data show that PET/MRI is clinically feasible and performs as well as PET/CT in most types of cancer. However, in the majority of PET/MRI clinical researches, MRI images were used to provide anatomic details for PET signal, rather than focusing on the potential synergy between the capabilities of functional MRI and molecular PET [1].In addition, given the potential for technological development, efforts should also be made by researchers to compare the diagnostic performance of the two hybrid imaging technologies and their influence on further clinical management, in particular by fully exploring the potential of PET/MRI.Although there is still a lack of clearly defined PET/MRI key applications, there are some obvious advantages on using PET/MRI over PET/CT that cannot be unnoticed: there are all the clinical cases where patients need to perform both PET and MRI studies for the evaluation of their disease. The opportunity of performing both examinations in the same study session is a clear benefit in term of patient convenience, being easier than having to go for a PET and MR separately, and much less time-consuming. Another great advantage of PET/MR with respect to PET/ CT is that patients have much less radiation exposure: M...

Cellular Neural Networks Templates Learning Approach Based on Mutual Information and Firefly Algorithm for X-Ray Images de-noising

“…For each repetition, the worst solution was identified after ranking as shown in Algorithm(3). Remaining candidates were led by the mean position obtained from (16) where σ denotes a random value obtained by logistic map as shown as follow:…”

“…𝑔 𝑏𝑒𝑠𝑡 ′ = 𝑚𝑒𝑎𝑛(𝑔 𝑏𝑒𝑠𝑡 + 𝑆 𝑏𝑒𝑠𝑡 ) + σ 2 (16) Where 𝑓 𝑖 (𝑡 + 1) represents the step movement of firefly 𝑗 towards the optimal region using ( 14) with a brighter attractiveness, and 𝑔 𝑏𝑒𝑠𝑡 ′ represents the better offspring solutions of the mean of the leader and the alternative fireflies as shown in (15). The variables 𝜎 1 and 𝜎 2 are two random variables set by the normal distribution.…”

“…The variables 𝜎 1 and 𝜎 2 are two random variables set by the normal distribution. The step of the firefly was calculated, as shown in (16). Where 𝐶 𝑘 denotes the chaotic variable in the step movement and 𝜀 represents the randomized vector pre-defined in the firefly algorithm.…”

Continuing Nuclear Data Research for Production of Accelerator-Based Novel Radionuclides for Medical Use: A Mini-Review

“…Bimodal imaging involves a combination of two organimaging techniques, for example, PET and magnetic resonance imaging (MRI) (for review cf [22]). From the viewpoint of PET, the major focus is on the elements Mn and Gd which are important contrast agents in MRI.…”