scholarly journals Magnetic Resonance Imaging Artifacts and Cochlear Implant Positioning at 1.5 T In Vivo

2018 ◽  
Vol 2018 ◽  
pp. 1-4 ◽  
Author(s):  
Dirk Schröder ◽  
Gloria Grupe ◽  
Grit Rademacher ◽  
Sven Mutze ◽  
Arneborg Ernst ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Cochlear Implant ◽  
Internal Auditory Canal ◽  
Resonance Imaging ◽  
Ear Canal ◽  
Cerebral Magnetic Resonance Imaging ◽  
Tertiary Referral Center ◽  
Weighted Sequences

Objective. Cerebral magnetic resonance imaging with the magnet of the cochlear implant receiver/stimulator in place causes artifacts and hinders evaluation of intracerebral structures. The aim of this study was to evaluate the internal auditory canal and the labyrinth in a 1.5T MRI with the magnet in place. Study Design. Observational study. Setting. Tertiary referral center. Subjects and Methods. The receiver/stimulator unit was placed and fixed onto the head of three volunteers at three different angles to the nasion–outer ear canal (90°–160°) and at three different distances from the outer ear canal (5–9 cm). T1 and T2 weighted sequences were conducted for each position. Results. Excellent visibility of the internal auditory canal and the labyrinth was seen in the T2 weighted sequences with 9 cm between the magnet and the outer ear canal at every nasion–outer ear canal angle. T1 sequences showed poorer visibility of the internal auditory canal and the labyrinth. Conclusion. Aftercare and visibility of intracerebral structures after cochlear implantation is becoming more important as cochlear implant indications are widened worldwide. With a distance of at least 9 cm from the outer ear canal the artifact induced by the magnet allows evaluation of the labyrinth and the internal auditory canal.

scholarly journals Evaluation of different magnetic resonance imaging contrast materials to be used as dummy markers in image-guided brachytherapy for gynecologic malignancies

2016 ◽  
Vol 49 (3) ◽  
pp. 165-169
Author(s):  
Camila Pessoa Sales ◽  
Heloisa de Andrade Carvalho ◽  
Khallil Chaim Taverna ◽  
Bruno Fraccini Pastorello ◽  
Rodrigo Augusto Rubo ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Water Solution ◽  
Contrast Material ◽  
Magnetic Resonance Images ◽  
Resonance Imaging ◽  
Dwell Position ◽  
Weighted Sequences

Abstract Objective: To identify a contrast material that could be used as a dummy marker for magnetic resonance imaging. Materials and Methods: Magnetic resonance images were acquired with six different catheter-filling materials-water, glucose 50%, saline, olive oil, glycerin, and copper sulfate (CuSO4) water solution (2.08 g/L)-inserted into compatible computed tomography/magnetic resonance imaging ring applicators placed in a phantom made of gelatin and CuSO4. The best contrast media were tested in four patients with the applicators in place. Results: In T2-weighted sequences, the best contrast was achieved with the CuSO4-filled catheters, followed by saline- and glycerin-filled catheters, which presented poor visualization. In addition (also in T2-weighted sequences), CuSO4 presented better contrast when tested in the phantom than when tested in the patients, in which it provided some contrast but with poor identification of the first dwell position, mainly in the ring. Conclusion: We found CuSO4 to be the best solution for visualization of the applicator channels, mainly in T2-weighted images in vitro, although the materials tested presented low signal intensity in the images obtained in vivo, as well as poor precision in determining the first dwell position.

Magnetic resonance imaging versus computed tomography in pre-operative evaluation of cochlear implant candidates with congenital hearing loss

2002 ◽  
Vol 116 (10) ◽  
pp. 804-810 ◽  
Author(s):  
Levent Sennaroglu ◽  
Isil Saatci ◽  
Ayse Aralasmak ◽  
Bulent Gursel ◽  
Ergin Turan
Keyword(s):  
Magnetic Resonance Imaging ◽  
Hearing Loss ◽  
Magnetic Resonance ◽  
Cochlear Implant ◽  
Sensorineural Hearing Loss ◽  
Internal Auditory Canal ◽  
Cochlear Nerve ◽  
Sensorineural Hearing ◽  
Congenital Hearing Loss ◽  
Resonance Imaging

Recent reports indicate that the cochlear nerve may be absent in some cases of congenital sensorineural hearing loss. The aim of this prospective study was to determine the incidence of cochlear nerve anomaly in cochlear implant candidates with congenital hearing loss using magnetic resonance imaging (MRI). Twenty-seven patients with congenital profound bilateral sensorineural hearing loss who were being evaluated for the cochlear implant procedure were studied.These patients had high-resolution computerized tomography (CT), through the petrous bone in axial sections. MRI examinations consisted of T1 and turbo spin echo (TSE) T2-weighted 3 mm axial images, and additional 3D Fourier Transform T2-weighted TSE sequences obtained on three different planes (axial, perpendicular and parallel to the internal auditory canal (IAC) i.e. oblique sagittal and coronal, respectively) for the purpose of cochlear nerve demonstration. Results showed that all of the 14 patients with normal CT of the temporal bone, had four distinct nerves in the distal part of the IAC on TSE-MRI. Thirteen patients demonstrated various bony malformations of the cochleovestibular system on CT. MRI revealed the absence of the cochleovestibular nerve in four patients where the IAC was very narrow or completely absent on CT. One patient with severe Mondini malformation who had an enlarged IAC demonstrated an isolated absent cochlear nerve.

scholarly journals Thickness of cerebral cortex measured using anatomical mesoscopic imaging and magnetic resonance imaging

Medicina ◽  
2008 ◽  
Vol 44 (2) ◽  
pp. 126
Author(s):  
Liuda Janauskaitë ◽  
Justina Kaèerauskienë ◽  
Ugnë Jaðinskaitë ◽  
Vytautas Gedrimas ◽  
Rimvydas Stropus
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cerebral Cortex ◽  
Magnetic Resonance ◽  
Magnetic Resonance Images ◽  
Imaging Method ◽  
Resonance Imaging ◽  
Cerebral Magnetic Resonance Imaging ◽  
Significant Difference ◽  
Age And Sex

Objective. Magnetic resonance imaging method opened up the possibility for in vivo examination of the anatomy of human brain. For this reason it is interesting and relevant to compare the knowledge accumulated over a number of years during the examination of the composition of dead brain to that obtained from magnetic resonance images. The aim of this study was to determine and compare the thickness of cerebral cortex in human of different age and sex, measured in different sites of the hemispheres when applying anatomical mesoscopic imaging and magnetic resonance imaging. Material and methods. The thickness of cerebral cortex was measured in symmetrical Brodmann’s areas of both hemispheres. The anatomical mesoscopic imaging technique was used for the examination of 2×2-cm cortex samples obtained during autopsy and fixed for 4 weeks in 10% paraformaldehyde. In these samples, cortex thickness was measured in sections perpendicular to the convolution, using an operative microscope, in a mesoscopic image at ×16 magnification and with an accuracy of 0.01 mm. Using cerebral magnetic resonance imaging, the thickness of cerebral cortex in live subjects was measured on T1-weighted images of patients examined at the Clinic of Radiology, Kaunas University of Medicine Hospital. The measured cortical field image was magnified to the smallest element of digital image – the pixel – and measured with an accuracy of 0.01 mm. Each of the two techniques was applied for the examination of 20 men and women who were divided into age groups of 20–60 years (n=10) and older than 60 years (n=10). Results and conclusions. Both examination methods yielded a statistically significant difference in the thickness of cerebral cortex between Brodmann’s areas 1, 4, and 19. No significant difference in cortex thickness was found between different age and sex groups; however, the findings showed that the difference in cortex thickness between the different age male groups was 4.6% and female – 1.6%. No significant difference using different techniques was found, but the cortex thickness in the fixed samples was reduced by 0.5 cm on average.

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