scholarly journals Relationship between Diffusivity of Water Molecules Inside Hydrating Tablets and Their Drug Release Behavior Elucidated by Magnetic Resonance Imaging

2012 ◽  
Vol 60 (4) ◽  
pp. 536-542 ◽  
Author(s):  
Shingo Kikuchi ◽  
Yoshinori Onuki ◽  
Hideto Kuribayashi ◽  
Kozo Takayama
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Drug Release ◽  
Water Molecules ◽  
Release Behavior ◽  
Resonance Imaging ◽  
Drug Release Behavior

scholarly journals Eccentric magnetic microcapsules for MRI-guided local administration and pH-regulated drug release

RSC Advances ◽  
2018 ◽  
Vol 8 (73) ◽  
pp. 41956-41965
Author(s):  
Jingxian Huang ◽  
Wenwei Huang ◽  
Yin Chen ◽  
Yu Shrike Zhang ◽  
Jinshuang Zhong ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Drug Release ◽  
Local Administration ◽  
Resonance Imaging ◽  
Mri Guided

Uniform eccentric magnetic microcapsules for magnetic resonance imaging-guided local administration and pH-regulated drug release were developed.

Magnetic resonance imaging of high-intensity focused ultrasound-stimulated drug release from a self-reporting core@shell nanoparticle platform

2020 ◽  
Vol 56 (71) ◽  
pp. 10297-10300
Author(s):  
Chi-An Cheng ◽  
Wei Chen ◽  
Le Zhang ◽  
Holden H. Wu ◽  
Jeffrey I. Zink
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Drug Release ◽  
High Intensity ◽  
Focused Ultrasound ◽  
High Intensity Focused Ultrasound ◽  
Core Shell ◽  
Resonance Imaging

A self-reporting theranostic approach that controls and “images” drug release from nanoparticles using magnetic resonance imaging-guided high-intensity focused ultrasound is presented.

Early Detection of Response to Radiation Therapy in Patients With Brain Malignancies Using Conventional and High b-Value Diffusion-Weighted Magnetic Resonance Imaging

2003 ◽  
Vol 21 (6) ◽  
pp. 1094-1100 ◽  
Author(s):  
Yael Mardor ◽  
Raphael Pfeffer ◽  
Roberto Spiegelmann ◽  
Yiftach Roth ◽  
Stephan E. Maier ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Radiation Therapy ◽  
Magnetic Resonance ◽  
Tumor Response ◽  
Bound Water ◽  
Water Molecules ◽  
Resonance Imaging ◽  
Diffusion Weighted ◽  
Diffusion Parameters ◽  
Weighted Magnetic Resonance Imaging

Purpose: To study the feasibility of using diffusion-weighted magnetic resonance imaging (DWMRI), which is sensitive to the diffusion of water molecules in tissues, for detection of early tumor response to radiation therapy; and to evaluate the additional information obtained from high DWMRI, which is more sensitive to low-mobility water molecules (such as intracellular or bound water), in increasing the sensitivity to response. Patients and Methods: Standard MRI and DWMRI were acquired before and at regular intervals after initiating radiation therapy for 10 malignant brain lesions in eight patients. Results: One week posttherapy, three of six responding lesions showed an increase in the conventional DWMRI parameters. Another three responding lesions showed no change. Four nonresponding lesions showed a decrease or no change. The early change in the diffusion parameters was enhanced by using high DWMRI. When high DWMRI was used, all responding lesions showed increase in the diffusion parameter and all nonresponding lesions showed no change or decrease. Response was determined by standard MRI 7 weeks posttherapy. The changes in the diffusion parameters measured 1 week after initiating treatment were correlated with later tumor response or no response (P < .006). This correlation was increased to P < .0006 when high DWMRI was used. Conclusion: The significant correlation between changes in diffusion parameters 1 week after initiating treatment and later tumor response or no response suggests the feasibility of using DWMRI for early, noninvasive prediction of tumor response. The ability to predict response may enable early termination of treatment in nonresponding patients, prevent additional toxicity, and allow for early changes in treatment.

scholarly journals r1andr2Relaxivities of Dendrons Based on a OEG-DTPA Architecture: Effect of Gd3+Placement and Dendron Functionalization

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Peter Fransen ◽  
Daniel Pulido ◽  
Lorena Simón-Gracia ◽  
Ana Paula Candiota ◽  
Carles Arús ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Molecular Weight ◽  
Magnetic Resonance ◽  
Contrast Agents ◽  
Signal Intensity ◽  
Water Molecules ◽  
Rotational Axis ◽  
Resonance Imaging ◽  
Magnetic Resonance Imaging Contrast ◽  
Strategic Position

In magnetic resonance imaging, contrast agents are employed to enhance the signal intensity. However, current commercial contrast agents are hindered by a low relaxivity constant. Dendrimers can be employed to create higher molecular weight contrast agents which have an increased relaxivity due to a lower molecular rotation. In this study, dendrimers containing DTPA derivatives as cores and/or branching units were used to chelate gadolinium ions. Locating the gadolinium ions inside the dendrimers results in higher relaxivity constants, possibly because the paramagnetic center is closer to the rotational axis of the macromolecule. The highest gain in relaxivity was produced by decorating the dendron surface with peptide sequences, which could be explained by the presence of more second-sphere water molecules attracted by the peptides. These findings could contribute to the development of more effective contrast agents, either by placing the paramagnetic gadolinium ion in a strategic position or through functionalization of the dendron surface.

The use of magnetic resonance imaging to track controlled drug release and transport in the brain

1993 ◽  
Vol 11 (2) ◽  
pp. 247-252 ◽  
Author(s):  
Bradley Reisfeld ◽  
Stephen Blackband ◽  
Vince Calhoun ◽  
Stuart Grossman ◽  
Susan Eller ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Drug Release ◽  
Controlled Drug Release ◽  
Resonance Imaging ◽  
The Brain

scholarly journals Ammonium Bisphosphonate Polymeric Magnetic Nanocomplexes for Platinum Anticancer Drug Delivery and Imaging with Potential Hyperthermia and Temperature-Dependent Drug Release

2018 ◽  
Vol 2018 ◽  
pp. 1-14
Author(s):  
Rui Zhang ◽  
Benjamin Fellows ◽  
Nikorn Pothayee ◽  
Nan Hu ◽  
Nipon Pothayee ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Field ◽  
Drug Delivery ◽  
Magnetic Resonance ◽  
Drug Release ◽  
Aqueous Media ◽  
Potential Drug ◽  
Resonance Imaging ◽  
Temperature Dependent ◽  
Hyperthermia Treatment

Novel magnetite-ammonium bisphosphonate graft ionic copolymer nanocomplexes (MGICs) have been developed for potential drug delivery, magnetic resonance imaging, and hyperthermia applications. The complexes displayed relatively uniform sizes with narrow size distributions upon self-assembly in aqueous media, and their sizes were stable under simulated physiological conditions for at least 7 days. The anticancer drugs, cisplatin and carboplatin, were loaded into the complexes, and sustained release of both drugs was observed. The transverse NMR relaxivities (r2s) of the complexes were 244 s−1 (mM Fe)−1 which is fast compared to either the commercial T2-weighted MRI agent Feridex IV® or our previously reported magnetite-block ionomer complexes. Phantom MRI images of the complexes demonstrated excellent negative contrast effects of such complexes. Thus, the bisphosphonate-bearing MGICs could be promising candidates for dual drug delivery and magnetic resonance imaging. Moreover, the bisphosphonate MGICs generate heat under an alternating magnetic field of 30 kA·m−1 at 206 kHz. The temperature of the MGIC dispersion in deionized water increased from 37 to 41°C after exposure to the magnetic field for 10 minutes, corresponding to a specific absorption rate of 77.0 W·g−1. This suggests their potential as hyperthermia treatment agents as well as the possibility of temperature-dependent drug release, making MGICs more versatile in potential drug delivery applications.

scholarly journals Quantitation of slow drug release from an implantable and degradable gentamicin conjugate by in vivo magnetic resonance imaging.

1995 ◽  
Vol 39 (4) ◽  
pp. 839-845 ◽  
Author(s):  
R Weissleder ◽  
K Poss ◽  
R Wilkinson ◽  
C Zhou ◽  
A Bogdanov
Keyword(s):  
Magnetic Resonance Imaging ◽  
Polyethylene Glycol ◽  
Magnetic Resonance ◽  
Drug Release ◽  
Lethal Dose ◽  
Dimensional Structure ◽  
Therapeutic Drug ◽  
Resonance Imaging ◽  
Drug Concentrations

A biodegradable model hydrogel containing a covalently bound aminoglycoside in which drug release can be monitored by magnetic resonance imaging (MRI) in vivo was developed. The hydrogel consists of the bishydroxysuccinimide ester of polyethylene glycol disuccinate cross-linked albumin, to which gentamicin and Gd-diethylenetriaminepentaacetic acid are covalently attached in stochiometric quantities. MRI allowed us to depict the three-dimensional structure of implanted gels, to accurately calculate their volumes, and thus to calculate the concentration of hydrogel-bound gentamicin. The correlation coefficient for the concentration of released gentamicin and the hydrogel volume was 0.965. Free and hydrogel-released gentamicin conjugates had similar antibiotic efficacies when tested in microbiological agar diffusion assays. In vivo, hydrogel-released gentamicin had a longer half-life in plasma than unaltered gentamicin (5.6 versus 0.7 h), presumably because of residual bound polyethylene glycol residues. Hydrogel implants into rats resulted in a prolonged (7 to 10 days) release of gentamicin and a decreased 24-h mortality in mice infected with a lethal dose of Pseudomonas aeruginosa. The results indicate the feasibility of imaging and quantitating therapeutic drug concentrations in vivo by MRI.

scholarly journals Towards an image-guided restricted drug release in friendly implanted therapeutics

2018 ◽  
Vol 82 (3) ◽  
pp. 31401
Author(s):  
Adel Razek
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Drug Release ◽  
Minimally Invasive ◽  
Electromagnetic Compatibility ◽  
Resonance Imaging ◽  
Mr Image ◽  
Image Guided ◽  
Compatibility Analysis ◽  
Position Detection

This review aims to expose a possible therapeutics scheme of using active implants for restricted drug release accounting for friendly wellbeing and security of patient. The review of embedded therapeutics, regulated drug administration, minimally-invasive issues and governing non-ionizing position detection suggested a possible MR image-guided approach. The magnetic resonance imaging is then investigated and its environmental compatibility is explored through electromagnetic compatibility analysis for embedded therapeutics.

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