scholarly journals Magnetic Colloidal Particles in Combinatorial Thin-Film Gradients for Magnetic Resonance Imaging and Hyperthermia

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Sumera Khizar ◽  
Nasir Mahmood Ahmad ◽  
Hassan Saleem ◽  
Muhammad Asif Hamayun ◽  
Sadia Manzoor ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Thin Film ◽  
Magnetic Resonance ◽  
Colloidal Particles ◽  
Aqueous Media ◽  
Research Work ◽  
Layer By Layer ◽  
Resonance Imaging ◽  
Signal Intensities ◽  
T2 Weighted Images

A stable oil-in-water (O/W) magnetic emulsion was prepared by the emulsification of organic ferrofluid in an aqueous media, and its theranostic applications were investigated. The synthesis and characterization of the organic ferrofluid were carried out comprising of superparamagnetic maghemite nanoparticles with oleic acid coating stabilized in octane. Both exhibit spherical morphology with a mean size of 6 nm and 200 nm, respectively, as determined by TEM. Thermogravimetric analysis was carried out to determine the chemical composition of the emulsion. The research work described here is novel and elaborates the fabrication of thin-film gradients with 5, 10, 15, and 20 bilayers by layer-by-layer technique using polydimethyl diallyl ammonium chloride (PDAC) and prepared magnetic colloidal particles. The thin-film gradients were characterized for their roughness, morphology, and wettability. The developed gradient films and colloids were explored in magnetic resonance imaging (MRI) and hyperthermia. T1- and T2-weighted images and their corresponding signal intensities were obtained at 1.5 T. A decreasing trend in signal intensities with an increase in nanoparticle concentration in colloids and along the gradient was observed in T2-weighted images. The hyperthermia capability was also evaluated by measuring temperature rise and calculating specific absorption rates (SAR). The SAR of the colloids at 259 kHz, 327 kHz, and 518 kHz were found to be 156 W/g, 255 W/g, and 336 W/g, respectively. The developed magnetic combinatorial thin-film gradients present a significant potential for the future efficient simultaneous diagnostic and therapeutic bioapplications.

scholarly journals pH Tunable Thin Film Gradients of Magnetic Polymer Colloids for MRI Diagnostics

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2116
Author(s):  
Sumera Khizar ◽  
Nasir M. Ahmad
Keyword(s):  
Magnetic Resonance Imaging ◽  
Thin Film ◽  
Magnetic Resonance ◽  
Biological Fluids ◽  
Point Of Care ◽  
Layer By Layer ◽  
Resonance Imaging ◽  
Polymer Colloids ◽  
Lab On Chip

Magnetic polymer colloids comprising of magnetite (Fe3O4) nanoparticles and Eudragit E100 were employed to fabricate thin film gradients and were investigated for in-vitro magnetic resonance imaging. Magnetic polymer colloids (MPC) and polyacrylic acid (PAA) with stimuli-responsive cationic and anionic functional groups respectively facilitate the formation of thin film gradients via layer by layer technique. The characteristics of films were controlled by changing the pH and level of the adsorbing solutions that lead to the development of gradient films having 5.5, 10.5 and 15.5 bilayers. Optical microscopy, scanning electron microscopy and magnetic force microscopy was carried out to determine the surface coverage of films. Surface wettability demonstrated the hydrophilicity of adsorbed colloids. The developed thin-film gradients were explored for in vitro magnetic resonance imaging that offers a point of care lab-on-chip as a dip-stick approach for ultrasensitive in-vitro molecular diagnosis of biological fluids.

scholarly journals Follow-up magnetic resonance imaging of Löffler endocarditis: a case report

2020 ◽  
Author(s):  
Shinya Ito ◽  
Akihiro Isotani ◽  
Kyohei Yamaji ◽  
Kenji Ando
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Corticosteroid Therapy ◽  
Cardiac Mri ◽  
High Intensity ◽  
Left Ventricular ◽  
Eosinophil Infiltration ◽  
Resonance Imaging ◽  
T2 Weighted Images

Abstract Background  Löffler endocarditis is a condition characterized by cardiac infiltration of eosinophils. Cardiac magnetic resonance imaging (MRI) is a modality for the diagnosis of myocardial damage. Case summary  This is the case of a 77-year-old man with acute decompensated heart failure who was admitted. Transthoracic echocardiography showed preserved left ventricular (LV) systolic function along with LV thrombi attached to the septo-apical wall and the posterior wall, consistent with Löffler endocarditis. Cardiac MRI revealed obliteration of the LV apex and partial filling of the LV cavity, as well as near circumferential subendocardial late gadolinium enhancement (LGE) in the mid- and apical segments. T2-weighted images showed a near circumferential high-intensity area of the LV subendocardial muscle in the mid- and apical segments. High-dose corticosteroids and intravenous heparin were initiated, followed by maintenance warfarin therapy. At 18 months, follow-up cardiac MRI revealed the disappearance of the LV thrombi, and a reduction of LGE, as well as high-intensity areas in the T2-weighted images. Discussion  The high-intensity area of T2-weighted images indicate the presence of subendocardial oedema. Eosinophil-mediated heart damage evolves through three stages: (i) acute necrotic, (ii) thrombotic, and (iii) fibrotic stages. Since the deposition of toxic eosinophil granule proteins and eosinophil infiltration injured the endocardium, the first-line treatment for Löffler endocarditis is corticosteroid therapy. In this case, LGE in the subendocardium and the high-intensity area in the T2-weighted images were reduced at 18 months. High-intensity areas of T2-weighted images in the acute phase might indicate the possibility of therapeutic response to corticosteroid therapy.

scholarly journals Glassy carbon microelectrodes minimize induced voltages, mechanical vibrations, and artifacts in magnetic resonance imaging

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Surabhi Nimbalkar ◽  
Erwin Fuhrer ◽  
Pedro Silva ◽  
Tri Nguyen ◽  
Martin Sereno ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Thin Film ◽  
Finite Element ◽  
Magnetic Resonance ◽  
Finite Element Modeling ◽  
Glassy Carbon ◽  
Resonance Imaging ◽  
Neural Probes ◽  
Element Modeling ◽  
Polymeric Substrates

AbstractThe recent introduction of glassy carbon (GC) microstructures supported on flexible polymeric substrates has motivated the adoption of GC in a variety of implantable and wearable devices. Neural probes such as electrocorticography and penetrating shanks with GC microelectrode arrays used for neural signal recording and electrical stimulation are among the first beneficiaries of this technology. With the expected proliferation of these neural probes and potential clinical adoption, the magnetic resonance imaging (MRI) compatibility of GC microstructures needs to be established to help validate this potential in clinical settings. Here, we present GC microelectrodes and microstructures—fabricated through the carbon micro-electro-mechanical systems process and supported on flexible polymeric substrates—and carry out experimental measurements of induced vibrations, eddy currents, and artifacts. Through induced vibration, induced voltage, and MRI experiments and finite element modeling, we compared the performances of these GC microelectrodes against those of conventional thin-film platinum (Pt) microelectrodes and established that GC microelectrodes demonstrate superior magnetic resonance compatibility over standard metal thin-film microelectrodes. Specifically, we demonstrated that GC microelectrodes experienced no considerable vibration deflection amplitudes and minimal induced currents, while Pt microelectrodes had significantly larger currents. We also showed that because of their low magnetic susceptibility and lower conductivity, the GC microelectrodes caused almost no susceptibility shift artifacts and no eddy-current-induced artifacts compared to Pt microelectrodes. Taken together, the experimental, theoretical, and finite element modeling establish that GC microelectrodes exhibit significant MRI compatibility, hence demonstrating clear clinical advantages over current conventional thin-film materials, further opening avenues for wider adoption of GC microelectrodes in chronic clinical applications.

scholarly journals Correlation of magnetic resonance imaging and post-ablation endoscopy to detect oesophageal thermal injury in patients after atrial fibrillation ablation: MRI-EDEL-study

EP Europace ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 1009-1016
Author(s):  
Philipp Halbfass ◽  
Lukas Lehmkuhl ◽  
Borek Foldyna ◽  
Artur Berkovitz ◽  
Kai Sonne ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Atrial Fibrillation ◽  
Magnetic Resonance ◽  
Predictive Value ◽  
Diagnostic Value ◽  
Resonance Imaging ◽  
Oesophageal Injury ◽  
Mri Sequences ◽  
Sensitivity Specificity ◽  
Signal Intensities

Abstract Aims  To correlate oesophageal magnetic resonance imaging (MRI) abnormalities with ablation-induced oesophageal injury detected in endoscopy. Methods and results  Ablation-naïve patients with atrial fibrillation (AF), who underwent ablation using a contact force sensing irrigated radiofrequency ablation catheter, received a cardiac MRI on the day of ablation, and post-ablation oesophageal endoscopy (OE) 1 day after ablation. Two MRI expert readers recorded presence of abnormal oesophageal tissue signal intensities, defined as increased oesophageal signal in T2-fat-saturated (T2fs), short-tau inversion-recovery (STIR), or late gadolinium enhancement (LGE) sequences. Oesophageal endoscopy was performed by experienced operators. Finally, we correlated the presence of any affection with endoscopically detected oesophageal thermal lesions (EDEL). Among 50 consecutive patients (age 67 ± 7 years, 60% male), who received post-ablation MRI and OE, complete MRI data were available in 44 of 50 (88%) patients. In OE, 7 of 50 (14%) presented with EDEL (Category 1 lesion: erosion n = 3, Category 2 lesion: ulcer n = 4). Among those with EDEL, 6 of 7 (86%) patients presented with increased signal intensities in all three MRI sequences, while only 2 of 37 (5%) showed hyperintensities in all three MRI sequences and negative endoscopy. Correspondingly, sensitivity, specificity, positive predictive value, and negative predictive value (NPV) for MRI (increased signal in T2fs, STIR, and LGE) were 86%, 95%, 75%, and 97%, respectively. Conclusion  Increased signal intensity in T2fs, STIR, and LGE represents independent markers of EDEL. In particular, the combination of all three has the highest diagnostic value. Hence, MRI may represent an accurate, non-invasive method to exclude acute oesophageal injury after AF ablation (NPV: 97%).

Magnetic Resonance Imaging and Cervical Spondylotic Myelopathy

Neurosurgery ◽  
1990 ◽  
Vol 26 (2) ◽  
pp. 217-227 ◽  
Author(s):  
Thomas F. Mehalic ◽  
Roger T. Pezzuti ◽  
Brett I. Applebaum
Keyword(s):  
Magnetic Resonance Imaging ◽  
Spinal Cord ◽  
Magnetic Resonance ◽  
Signal Intensity ◽  
Cervical Spondylotic Myelopathy ◽  
Pathological Condition ◽  
Prognostic Significance ◽  
Resonance Imaging ◽  
T2 Weighted Images

Abstract Nineteen patients were examined for cervical spondylotic myelopathy with magnetic resonance imaging. Pre- and postoperative magnetic resonance scans were obtained in most cases. Surgical confirmation of the pathological condition was obtained for all 19 patients. On the T2-weighted scans, there was increased signal intensity within the spinal cord at the point of maximal compression. The exact cause of the increased signal intensity on the T2-weighted images is not known, but is suspected to represent edema, inflammation, vascular ischemia, myelomalacia, or gliosis. The increased signal intensity diminished postoperatively in the patients who improved clinically, and remained the same or increased in those whose conditions remained unchanged or worsened after decompression. The authors suggest that these T2-weighted images carry prognostic significance.

scholarly journals Contrast Enhancement of the Brain by Folate-Conjugated Gadolinium–Diethylenetriaminepentaacetic Acid–Human Serum Albumin Nanoparticles by Magnetic Resonance Imaging

2012 ◽  
Vol 11 (4) ◽  
pp. 7290.2011.00047 ◽  
Author(s):  
Huedayi Korkusuz ◽  
Karsten Ulbrich ◽  
Verena Bihrer ◽  
Katerina Welzel ◽  
Valery Chernikov ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Human Serum Albumin ◽  
Serum Albumin ◽  
Contrast Agents ◽  
Diethylenetriaminepentaacetic Acid ◽  
Resonance Imaging ◽  
Mri Contrast ◽  
The Brain ◽  
Signal Intensities

Different from regular small molecule contrast agents, nanoparticle-based contrast agents have a longer circulation time and can be modified with ligands to confer tissue-specific contrasting properties. We evaluated the tissue distribution of polymeric nanoparticles (NPs) prepared from human serum albumin (HSA), loaded with gadolinium–diethylenetriaminepentaacetic acid (Gd-DTPA) (Gd-HSA-NP), and coated with folic acid (FA) (Gd-HSA-NP-FA) in mice by magnetic resonance imaging (MRI). FA increases the affinity of the Gd-HSA-NP to FA receptor–expressing cells. Clinical 3 T MRI was used to evaluate the signal intensities in the different organs of mice injected with Gd-DTPA, Gd-HSA-NP, or Gd-HSA-NP-FA. Signal intensities were measured and standardized by calculating the signal to noise ratios. In general, the NP-based contrast agents provided stronger contrasting than Gd-DTPA. Gd-HSA-NP-FA provided a significant contrast enhancement (CE) in the brain ( p = .0032), whereas Gd-DTPA or Gd-HSA-NP did not. All studied MRI contrast agents showed significant CE in the blood, kidney, and liver ( p < .05). Gd-HSA-NP-FA elicited significantly higher CE in the blood than Gd-HSA-NP ( p = .0069); Gd-HSA-NP and Gd-HSA-NP-FA did not show CE in skeletal muscle and gallbladder; Gd-HSA-NP, but not Gd-HSA-NP-FA, showed CE in the cardiac muscle. Gd-HSA-NP-FA has potential as an MRI contrast agent in the brain.

Aneurysmal bone cyst

1993 ◽  
Vol 83 (10) ◽  
pp. 595-597 ◽  
Author(s):  
RG Schmidt ◽  
YM Kabbani ◽  
DP Mayer
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Aneurysmal Bone Cyst ◽  
Signal Intensity ◽  
Bone Cyst ◽  
Bone Lesion ◽  
Resonance Imaging ◽  
Weighted Magnetic Resonance Imaging ◽  
Fluid Levels ◽  
T2 Weighted Images

Key findings that aid in the diagnosis of an aneurysmal bone cyst are: 1) typically the patients are young individuals less than 20 years old; 2) an expansile bone lesion is bordered by a thin, low signal intensity rim mass; 3) the lesion is inhomogenously increased in signal on T2-weighted images; and 4) multiple fluid-fluid levels are seen with the mass on T2-weighted magnetic resonance imaging scans.

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