Potential heating caused by intraparenchymal intracranial pressure transducers in a 3-tesla magnetic resonance imaging system using a body radiofrequency resonator: assessment of the Codman MicroSensor Transducer

2008 ◽  
Vol 109 (1) ◽  
pp. 159-164 ◽  
Author(s):  
Virginia F. J. Newcombe ◽  
Robert C. Hawkes ◽  
Sally G. Harding ◽  
Roslyn Willcox ◽  
Sarah Brock ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Intracranial Pressure ◽  
Mr Imaging ◽  
Imaging System ◽  
Resonance Imaging ◽  
Mr Conditional ◽  
Body Coil ◽  
Codman Microsensor ◽  
Head Coil

Magnetic resonance imaging and spectroscopy may provide important clinical information in the acute stages of brain injury. For this to occur it must be ensured that intracranial pressure (ICP) monitoring devices are safe to bring into the MR imaging suite. The authors tested a Codman MicroSensor ICP Transducer (Codman & Shurtleff, Inc.) within a 3-T MR imaging system using the transmit body coil and receive-only coils and the transmit-and-receive head coil. Extreme and rapid heating of 64°C was noted with the transducer wire in certain positions when using the transmit body coil and receive-only head coil. This is consistent with the phenomenon of resonance, and the probe was shown to have a distinct resonant response when coupled to HP 4195A Network Analyzer (Hewlett Packard). Coiling some of the transducer wire outside of the receive-only head coil reduced the generated current and so stopped the thermogenesis. This may be due to the introduction of a radiofrequency choke. The ICP transducer performed within clinically acceptable limits in both the static magnetic field and during imaging with high radiofrequency power when the excess wire was in this configuration. No heating was observed when a transmit-and-receive head coil was used. This study has shown when using a high-field magnet, the Codman ICP probe is MR conditional. That is, in the authors' system, it can be safely used with the transmit-and-receive head coil, but when using the transmit body coil the transducer wire must be coiled into concentric loops outside of the receive-only head coil.

scholarly journals The Safety of MR Conditional Cochlear Implant at 1.5 Tesla Magnetic Resonance Imaging System

2016 ◽  
Vol 72 (8) ◽  
pp. 674-680 ◽  
Author(s):  
Daisuke Takahashi ◽  
Akio Ogura ◽  
Norio Hayashi ◽  
Shinya Seino ◽  
Ryosuke Kawai ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Cochlear Implant ◽  
Imaging System ◽  
Magnetic Resonance Imaging System ◽  
Resonance Imaging ◽  
Mr Conditional

Interactive magnetic resonance imaging—guided management of intracranial cystic lesions by using an open magnetic resonance imaging system

2001 ◽  
Vol 95 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Spyros S. Kollias ◽  
René L. Bernays
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Mr Imaging ◽  
Real Time ◽  
Imaging System ◽  
Resonance Imaging ◽  
Content Type ◽  
Imaging Guidance ◽  
Brain Abscesses ◽  
Fine Print

Object. The authors present their experience with neurosurgical procedures requiring real-time imaging feedback such as aspiration of a cystic structure or abscess cavity, decompression of hydrocephalic ventricles, management of arachnoid cysts, and installation of permanent or temporary drainage conduits, in which interactive magnetic resonance (MR) imaging guidance was used to monitor structural alterations associated with the procedure. Methods. Drainage of eight intraparenchymal brain abscesses in seven patients, decompression of space-occupying cystic or necrotic brain tumors in four patients, and endoscopic management of hydrocephalus associated with arachnoid cysts in three patients were performed using MR imaging—guided frameless stereotaxy in an open-configuration 0.5-tesla superconducting MR imaging system. Intraoperative MR imaging guidance provided accurate information on the course of the surgical procedure and associated intraoperative changes in tissue position, such as the degree of cyst aspiration, the presence or absence of hemorrhage or induced swelling, and changes associated with decompression of adjacent brain parenchyma and the ventricular system. No clinically significant complications were encountered in any patient. There were no targeting errors, and procedural objectives were accomplished in all cases. Conclusions. Drainage of brain abscesses, punctures of cystic or necrotic intracranial lesions with subsequent aspiration, and management of hydrocephalus can be performed safely and accurately by monitoring the procedure using real-time MR imaging to obtain immediate feedback on associated dynamic tissue changes.

scholarly journals A Gadolinium(III) Complex Based on the Thymine Nucleobase with Properties Suitable for Magnetic Resonance Imaging

2021 ◽  
Vol 22 (9) ◽  
pp. 4586
Author(s):  
Marta Orts-Arroyo ◽  
Amadeo Ten-Esteve ◽  
Sonia Ginés-Cárdenas ◽  
Isabel Castro ◽  
Luis Martí-Bonmatí ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Mr Imaging ◽  
Lesion Detection ◽  
Resonance Imaging ◽  
X Ray Diffraction ◽  
Functional Images ◽  
High Relaxivity ◽  
Contrast Enhanced ◽  
Phantom Studies

The paramagnetic gadolinium(III) ion is used as contrast agent in magnetic resonance (MR) imaging to improve the lesion detection and characterization. It generates a signal by changing the relaxivity of protons from associated water molecules and creates a clearer physical distinction between the molecule and the surrounding tissues. New gadolinium-based contrast agents displaying larger relaxivity values and specifically targeted might provide higher resolution and better functional images. We have synthesized the gadolinium(III) complex of formula [Gd(thy)2(H2O)6](ClO4)3·2H2O (1) [thy = 5-methyl-1H-pyrimidine-2,4-dione or thymine], which is the first reported compound based on gadolinium and thymine nucleobase. 1 has been characterized through UV-vis, IR, SEM-EDAX, and single-crystal X-ray diffraction techniques, and its magnetic and relaxometric properties have been investigated by means of SQUID magnetometer and MR imaging phantom studies, respectively. On the basis of its high relaxivity values, this gadolinium(III) complex can be considered a suitable candidate for contrast-enhanced magnetic resonance imaging.

5377679 Magnetic resonance imaging system

1995 ◽  
Vol 13 (6) ◽  
pp. VI-VII
Author(s):  
Machida Yoshio ◽  
Hatanaka Masahiko ◽  
Kitane Shinichi
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Imaging System ◽  
Magnetic Resonance Imaging System ◽  
Resonance Imaging

scholarly journals Lhermitte–Duclos Disease: Incidental Finding in Traumatic Cerebral Hemorrhage

2021 ◽  
Author(s):  
Hemant Kumar Beniwal ◽  
Thatikonda Satish ◽  
Gollapudi Prakash Rao ◽  
Musali Siddartha Reddy ◽  
Srikrishnaaditya Manne
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Intracranial Pressure ◽  
Cerebellar Ataxia ◽  
Cerebral Hemorrhage ◽  
Incidental Finding ◽  
Cowden Syndrome ◽  
Young Female ◽  
Resonance Imaging ◽  
Increased Intracranial Pressure

AbstractLhermitte–Duclos disease, also known as dysplastic cerebellar gangliocytoma, is a rare hamartomatous tumor localized in cerebellum. An association with Cowden syndrome is observed in 50% of cases who present with symptoms of increased intracranial pressure and cerebellar ataxia. These patients have specific magnetic resonance imaging and histopathological findings. Surgical resection is the treatment of choice. Here, we report a case of a young female with traumatic frontal hemorrhage associated with Lhermitte–Duclos disease.

scholarly journals Migraine or idiopathic intracranial hypertension: Magnetic resonance venography and magnetic resonance imaging findings

2020 ◽  
Vol 33 (3) ◽  
pp. 244-251
Author(s):  
Aynur Guliyeva ◽  
Melda Apaydin ◽  
Yesim Beckmann ◽  
Gulten Sezgin ◽  
Fazil Gelal
Keyword(s):  
Magnetic Resonance Imaging ◽  
Optic Nerve ◽  
Magnetic Resonance ◽  
Intracranial Pressure ◽  
Pituitary Gland ◽  
Optic Nerve Sheath ◽  
Imaging Findings ◽  
Resonance Imaging ◽  
Chi Square ◽  
Nerve Sheath

Background Idiopathic intracranial hypertension (IIH) is a disease characterised by increased cerebral pressure without a mass or hydrocephalus. We aimed to differentiate migraine and IIH patients based on imaging findings. Results Patients with IIH ( n = 32), migraine patients ( n = 34) and control subjects ( n = 33) were evaluated. Routine magnetic resonance imaging, contrast-enhanced 3D magnetic resonance venography and/or T1-weighted 3D gradient-recalled echo were taken with a 1.5 T magnetic resonance scanner. Optic-nerve sheath distention, flattened posterior globe and the height of the pituitary gland were evaluated in the three groups. Transverse sinuses (TS) were evaluated with respect to score of attenuation/stenosis and distribution. Pearson chi-square, Fisher’s exact test and chi-square trend statistical analyses were used for comparisons between the groups. A p-value of <0.05 was considered statistically significant. Decreased pituitary gland height, optic-nerve sheath distention and flattened posterior globe were found to be statistically significant ( p < 0.001) in IIH patients. Bilateral TS stenosis was also more common in IIH patients than in the control group and migraine group ( p = 0.02). Conclusion Decreased pituitary gland height, optic-nerve sheath distention, flattened posterior globe, bilateral stenosis and discontinuity in TS are significant findings in differentiating IIH cases from healthy individuals and migraine patients. Bilateral TS stenosis may be the cause rather than the result of increased intracranial pressure. The increase in intracranial pressure, which is considered to be responsible for the pathophysiology of IIH, is not involved in the pathophysiology of migraine.

Pontine ataxic hemiparesis studied by a high-resolution magnetic resonance imaging system

1987 ◽  
Vol 21 (2) ◽  
pp. 204-207 ◽  
Author(s):  
Hidehiko Nabatame ◽  
Hidenao Fukuyama ◽  
Ichiro Akiguchi ◽  
Masakuni Kameyama ◽  
Kazumasa Nishimura ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Imaging System ◽  
Magnetic Resonance Imaging System ◽  
Resonance Imaging ◽  
Ataxic Hemiparesis

scholarly journals Numerical Analysis of a Flexible Dual Loop Coil and its Experimental Validation for pre-Clinical Magnetic Resonance Imaging of Rodents at 7 T

2016 ◽  
Vol 16 (6) ◽  
pp. 294-299 ◽  
Author(s):  
S. Solis-Najera ◽  
F. Vazquez ◽  
R. Hernandez ◽  
O. Marrufo ◽  
A.O. Rodriguez
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Imaging System ◽  
Ex Vivo ◽  
Small Animal ◽  
Magnetic Resonance Imaging System ◽  
External Diameter ◽  
Rf Coil ◽  
Resonance Imaging ◽  
Clinical Magnetic Resonance Imaging

Abstract A surface radio frequency coil was developed for small animal image acquisition in a pre-clinical magnetic resonance imaging system at 7 T. A flexible coil composed of two circular loops was developed to closely cover the object to be imaged. Electromagnetic numerical simulations were performed to evaluate its performance before the coil construction. An analytical expression of the mutual inductance for the two circular loops as a function of the separation between them was derived and used to validate the simulations. The RF coil is composed of two circular loops with a 5 cm external diameter and was tuned to 300 MHz and 50 Ohms matched. The angle between the loops was varied and the Q factor was obtained from the S11 simulations for each angle. B1 homogeneity was also evaluated using the electromagnetic simulations. The coil prototype was designed and built considering the numerical simulation results. To show the feasibility of the coil and its performance, saline-solution phantom images were acquired. A correlation of the simulations and imaging experimental results was conducted showing a concordance of 0.88 for the B1 field. The best coil performance was obtained at the 90° aperture angle. A more realistic phantom was also built using a formaldehyde-fixed rat phantom for ex vivo imaging experiments. All images showed a good image quality revealing clearly defined anatomical details of an ex vivo rat.

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