scholarly journals Dimensions and Forms of Artefacts in 1.5T and 3T MRI Caused by Cochlear Implants

2021 ◽  
Author(s):  
Timo Maria Gottfried ◽  
Daniel Dejaco ◽  
Natalie Fischer ◽  
Veronika Innerhofer ◽  
Lejo Chacko ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Cochlear Implants ◽  
Standard Treatment ◽  
Resonance Imaging ◽  
3T Mri ◽  
Mri Scans ◽  
Void Area ◽  
Signal Void ◽  
Shape And Size

Abstract Introduction:Cochlear implantation is a standard treatment option due to expanding indicationsCranial magnetic resonance imaging (cMRI) has become a widespread diagnostic tool. Therefore, an increased number of cochlear implant (CI) users are undergoing cMRI scans.This study aimed to investigate the issue of the CI magnet impacting MRI quality and artifacts.Material and Methods:1.5T and 3T MRI scans with 4 defined sequences (T2-TSE, T2-TIRM, T1-3D-MPRAGE, and TDI) were performed on a phantom with a CI (Synchrony® System by MEDEL Austria®) in place. The resulting MRI artifacts were retrospectively compared to MRI artifacts observed in patients with a CI. All images were transferred to Amira® and visualized by manual segmentation.Results:Usable image quality was achieved in three sequences(T2-TSE, T2-TIRM and T1-mprage). Observed artifacts differed in shape and size depending on the sequence. Maximum diameters of fully extinguished areas ranged from 58x108x98 mm to 127x123x153 mm. Image distortions were larger.Conclusion:MRI artifacts caused by the Synchrony® system are asymmetric with varying shape, depending on the sequence. The phantom artefacts are similar to those in CI users. Considering the observed asymmetry, the hypothesis of varying implantation locations resulting in varying positions of the signal void area needs to be further investigated.

scholarly journals Magnetic resonance imaging (MRI) scans in patients with dorsal root ganglion stimulation

Pain Practice ◽  
2021 ◽  
Author(s):  
Marco Reining ◽  
Dirk Winkler ◽  
Joachim Boettcher ◽  
Juergen Meixensberger ◽  
Michael Kretzschmar
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Dorsal Root Ganglion ◽  
Dorsal Root ◽  
Resonance Imaging ◽  
Mri Scans ◽  
Magnetic Resonance Imaging Mri

scholarly journals Safety aspects of the PiCCO thermodilution-cardiac output catheter during magnetic resonance imaging at 3 Tesla

2021 ◽  
Author(s):  
Marieke Voet ◽  
Christiaan G. Overduin ◽  
Ernst L. Stille ◽  
Jurgen J. Fütterer ◽  
Joris Lemson
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cardiac Output ◽  
Magnetic Resonance ◽  
Critically Ill ◽  
Cardiac Output Monitoring ◽  
Measured Temperature ◽  
Resonance Imaging ◽  
Worst Case ◽  
Thermodilution Cardiac Output ◽  
3T Mri

AbstractThermodilution cardiac output monitoring, using a thermistor-tipped intravascular catheter, is used in critically ill patients to guide hemodynamic therapy. Often, these patients also need magnetic resonance imaging (MRI) for diagnostic or prognostic reasons. As thermodilution catheters contain metal, they are considered MRI-unsafe and advised to be removed prior to investigation. However, removal and replacement of the catheter carries risks of bleeding, perforation and infection. This research is an in vitro safety assessment of the PiCCO™ thermodilution catheter during 3 T Magnetic Resonance Imaging (3T-MRI).  In a 3T-MRI environment, three different PiCCO™ catheter sizes were investigated in an agarose-gel, tissue mimicking phantom. Two temperature probes measured radiofrequency-induced heating; one at the catheter tip and one at a reference point. Magnetically induced catheter dislocation was assessed by visual observation as well as by analysis of the tomographic images. For all tested catheters, the highest measured temperature increase was 0.2 °C at the center of the bore and 0.3 °C under “worst-case” setting for the tested MRI pulse sequences. No magnetically induced catheter displacements were observed. Under the tested circumstances, no heating or dislocation of the PiCCO™ catheter was observed in a tissue mimicking phantom during 3T-MRI. Leaving the catheter in the critically ill patient during MRI investigation might pose a lower risk of complications than catheter removal and replacement.

scholarly journals Predictors of Spondylolysis on Magnetic Resonance Imaging in Adolescent Athletes With Low Back Pain

2021 ◽  
Vol 9 (4) ◽  
pp. 232596712199546
Author(s):  
Takuji Yokoe ◽  
Takuya Tajima ◽  
Hiroshi Sugimura ◽  
Shinichirou Kubo ◽  
Shotarou Nozaki ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Low Back Pain ◽  
Back Pain ◽  
Magnetic Resonance ◽  
Neurological Symptoms ◽  
Low Back ◽  
Resonance Imaging ◽  
Advanced Imaging ◽  
Adolescent Athletes ◽  
Mri Scans

Background: Spondylolysis and undiagnosed mechanical low back pain (UMLBP) are the main causes of low back pain (LBP) in adolescent athletes. No studies have evaluated the difference in clinical and radiographic factors between these 2 conditions. Furthermore, it remains unclear which adolescent athletes with LBP should undergo advanced imaging examination for spondylolysis. Purpose: To compare the clinical and radiographic factors of adolescent athletes with spondylolysis and UMLBP who did not have neurological symptoms or findings before magnetic resonance imaging (MRI) evaluation and to determine the predictors of spondylolysis findings on MRI. Study Design: Cohort study, Level of evidence, 3. Methods: The study population included 122 adolescent athletes aged 11 to 18 years who had LBP without neurological symptoms or findings and who underwent MRI. Of these participants, 75 were ultimately diagnosed with spondylolysis, and 47 were diagnosed with UMLBP. Clinical factors and the following radiographic parameters were compared between the 2 groups: spina bifida occulta, lumbar lordosis (LL) angle, and the ratio of the interfacet distance of L1 to that of L5 (L1:L5 ratio, %). A logistic regression analysis was performed to evaluate independent predictors of spondylolysis on MRI scans. Results: Significantly more athletes with spondylolysis were male (82.7% vs 48.9%; P < .001), had a greater LL angle (22.8° ± 8.1° vs 19.3° ± 8.5°; P = .02), and had a higher L1:L5 ratio (67.4% ± 6.3% vs 63.4% ± 6.6%; P = .001) versus athletes with UMLBP. A multivariate analysis revealed that male sex (odds ratio [OR], 4.66; P < .001) and an L1:L5 ratio of >65% (OR, 3.48; P = .003) were independent predictors of positive findings of spondylolysis on MRI scans. Conclusion: The study findings indicated that sex and the L1:L5 ratio are important indicators for whether to perform MRI as an advanced imaging examination for adolescent athletes with LBP who have no neurological symptoms and findings.

scholarly journals Magnetic resonance imaging in the diagnosis of white matter signal abnormalities

2018 ◽  
Vol 31 (4) ◽  
pp. 362-371 ◽  
Author(s):  
Ravi Datar ◽  
Asuri Narayan Prasad ◽  
Keng Yeow Tay ◽  
Charles Anthony Rupar ◽  
Pavlo Ohorodnyk ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
White Matter ◽  
Magnetic Resonance ◽  
Tertiary Care ◽  
Diagnostic Utility ◽  
Care Hospital ◽  
Resonance Imaging ◽  
Clinical Tool ◽  
Diagnostic Challenge ◽  
Mri Scans

Background White matter abnormalities (WMAs) pose a diagnostic challenge when trying to establish etiologic diagnoses. During childhood and adult years, genetic disorders, metabolic disorders and acquired conditions are included in differential diagnoses. To assist clinicians and radiologists, a structured algorithm using cranial magnetic resonance imaging (MRI) has been recommended to aid in establishing working diagnoses that facilitate appropriate biochemical and genetic investigations. This retrospective pilot study investigated the validity and diagnostic utility of this algorithm when applied to white matter signal abnormalities (WMSAs) reported on imaging studies of patients seen in our clinics. Methods The MRI algorithm was applied to 31 patients selected from patients attending the neurometabolic/neurogenetic/metabolic/neurology clinics at a tertiary care hospital. These patients varied in age from 5 months to 79 years old, and were reported to have WMSAs on cranial MRI scans. Twenty-one patients had confirmed WMA diagnoses and 10 patients had non-specific WMA diagnoses (etiology unknown). Two radiologists, blinded to confirmed diagnoses, used clinical abstracts and the WMSAs present on patient MRI scans to classify possible WMA diagnoses utilizing the algorithm. Results The MRI algorithm displayed a sensitivity of 100%, a specificity of 30.0% and a positive predicted value of 74.1%. Cohen’s kappa statistic for inter-radiologist agreement was 0.733, suggesting “good” agreement between radiologists. Conclusions Although a high diagnostic utility was not observed, results suggest that this MRI algorithm has promise as a clinical tool for clinicians and radiologists. We discuss the benefits and limitations of this approach.

Safety Issues in Magnetic Resonance Imaging Scan with Retention of Olympus Long Clips in the Gastrointestinal Tract

2021 ◽  
Vol 17 ◽  
Author(s):  
Cheng-Yi Wang ◽  
Wei-Chou Chang ◽  
Hsin-Hung Huang ◽  
Wei-Kuo Chang ◽  
Yu-Lueng Shih ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Magnetic Resonance Imaging Scan ◽  
Resonance Imaging ◽  
Endoscopic Clip ◽  
Serious Adverse Event ◽  
Safety Issues ◽  
Endoscopic Clips ◽  
Mri Scans ◽  
Magnetic Resonance Imaging Mri

Objective: Not all endoscopic clips are compatible with magnetic resonance imaging (MRI). The aim of this study is to investigate the safety of MRI-incompatible endoscopic clips in patients undergoing MRI scans. Methods: We retrospectively reviewed the medical records of patients who had received endoscopic clip placement of Olympus Long Clip MRI-incompatible clips and then had undergone MRI scans within two weeks in our hospital between 2014 and 2019. Results: A total of 44,292 patients had undergone an MRI examination at our hospital. Only 15 patients had MRI scans within two weeks after the endoscopic clip placement. Their median age was 65.5 years, and 12 of the 15 patients were men. At the time of the clip placement and MRI scan, four patients were taking anti-coagulation or anti-platelet agents. The indication for endoscopic clip placement of the 15 patients was mucosal/submucosal defect or hemorrhage and colonic perforation. Endoscopic clips were placed in the colon of 14 patients and in the stomach of only one patient for gastric hemorrhage. One patient experienced clip migration and three displayed artifacts in abdominal images. No patient complications of mortality, hemorrhage, or organ perforation occurred. Conclusion: No serious adverse event occurred during MRI scans of patients with MRI-incompatible clips in this study, suggesting that MRI-incompatible clips may be safe to use in MRI scans. However, this does not guarantee the safety of the Long Clip for MRI scans, as further tests are needed to verify that this clip is safe for use during MRI.

Magnetic Resonance Imaging to Investigate the Clinical Applicability of the Medial Femoral Trochlea Osteochondral Flap Within the Wrist

Hand ◽  
2022 ◽  
pp. 155894472110643
Author(s):  
Jimmy H. Daruwalla ◽  
Jan Skrok ◽  
Mitchell A. Pet ◽  
Aviram M. Giladi ◽  
James P. Higgins
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Sagittal Plane ◽  
Convex Surface ◽  
Radius Of Curvature ◽  
Resonance Imaging ◽  
Femoral Trochlea ◽  
Average Ratio ◽  
Mri Scans ◽  
Magnetic Resonance Imaging Mri

Background: The medial femoral trochlea (MFT) osteochondral flap is employed for reconstruction of unsalvageable scaphoid proximal pole nonunions. The convex surface of the cartilage-bearing proximal trochlea is used to replace the similarly contoured proximal scaphoid and articulate with the concave scaphoid fossa of the radius. A magnetic resonance imaging (MRI) comparison of the shape of the MFT as it relates to the native proximal scaphoid has not been previously performed. Our study aimed to quantifiably compare the shape of the MFT, proximal scaphoid, and scaphoid fossa. Methods: Using imaging processing software, we measured radius of curvature of the articular segments in MRI scans of 10 healthy subjects’ wrists and knees. Results: Compared with the scaphoid fossa, average ratio of the radius of circumference of the proximal scaphoid was 0.79 and 0.78 in the coronal and sagittal planes, respectively. Compared with the scaphoid fossa, average ratio of the radius of circumference of the MFT was 0.98 and 1.31 in the coronal and sagittal planes, respectively. The radius of curvature of the MFT was larger than the proximal scaphoid, in the coronal and sagittal planes. In the coronal plane, the MFT radius of curvature is nearly identical to the scaphoid fossa, a closer match than the scaphoid itself. In the sagittal plane, the radius of curvature of the MFT was larger than the radius of curvature of the scaphoid fossa. Conclusions: Our data suggest that the radius of curvature, in the sagittal and coronal planes, of the MFT and proximal scaphoid is disparate.

Transient splenial lesion of corpus callosum: A window to many diagnoses

2021 ◽  
Vol 12 (3) ◽  
pp. 114-120
Author(s):  
Fathima Hana Maqsood ◽  
Adarsh Kibballi Madhukeshwar ◽  
Abdul Rasheed Valiyapalathingal ◽  
Vinayaka U.S ◽  
Devadas Acharya ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Corpus Callosum ◽  
Frequent Occurrence ◽  
Resonance Imaging ◽  
Time Intervals ◽  
3T Mri ◽  
Splenial Lesion ◽  
Clinical Conditions

Transient splenial lesions (TSL) are not of frequent occurrence and are usually observed with other diseases. The mechanism of TSL development still unclear despite of various theories put forward. These are secondary lesions and their diagnosis is of importance to associate them with clinical conditions. Magnetic resonance imaging is the modality of diagnosing TSL and 3T MRI was used in this study. The study includes 10 cases of TSL with varied disease etiologies like migraine, trauma, infection, demyelination etc. All the cases had follow-up imaging which showed resolution of the lesions after varied time intervals. An attempt to correlate the various theories with each type of disease is done in this study.

Clinical Application of 7T Magnetic Resonance Imaging in Patients with Focal Cortical Dysplasia IIa and Epilepsy

2020 ◽  
pp. 1-9
Author(s):  
Tinghong Liu ◽  
Huilou Liang ◽  
Jianfei Cui ◽  
Kaibao Sun ◽  
Shaohui Zhang ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
White Matter ◽  
Magnetic Resonance ◽  
Focal Cortical Dysplasia ◽  
Cortical Dysplasia ◽  
Preoperative Imaging ◽  
Seizure Freedom ◽  
Resonance Imaging ◽  
3T Mri ◽  
Strength Grade

<b><i>Background:</i></b> Focal cortical dysplasia (FCD) is one of the most important pathogenic findings in patients with extratemporal lobe epilepsy. Magnetic resonance imaging (MRI)-negative is the most important negative factor to predict postoperative seizure freedom; however, FCD-I and part of FCD-IIa are MRI-negative on routine MRI. <b><i>Objectives:</i></b> To explore the diagnostic values of 7T MRI and its new scan sequences in epilepsy patients with FCD-IIa. <b><i>Methods:</i></b> To include patients with focal seizure and suspicious focal abnormal imaging on 3T MRI during preoperative evaluation and perform a 7T MRI scan with white matter-suppressed (WMS) and gray-white matter tissue border enhancement (GWBE) sequences, resective epilepsy surgery, and postoperative pathological finding of FCD-IIa. The preoperative qualitative and localization significance of 7T MRI and 3T MRI in lesions with FCD-IIa was compared, and then, the imaging characteristics of lesions with FCD-IIa on 7T MRI were analyzed. <b><i>Results:</i></b> Ten cases were enrolled in this study. Seven tesla MRI presented high spatial resolutions and a high signal-to-noise ratio. WMS and GWBE could selectively suppress the signal of special tissue and improved the possibility of FCD findings. FCD-IIa showed abnormal thickness of gray matter and a blurring border and was hypointense on 7T MRI compared with 3T MRI. Seven patients showed improvement in the qualitative diagnosis strength grade of FCD, and 6 subjects showed improvement in the localization strength grade of the lesion border after careful reading of the 7T MR images. Significant differences were found in the qualitative diagnosis of FCD (<i>p</i> &#x3c; 0.05) and localization of the lesion border (<i>p</i> &#x3c; 0.05) between the neuroimaging diagnoses based on 3T MRI and the findings based on 7T MRI. <b><i>Conclusion:</i></b> 7T MRI with WMS and GWBE sequences shows application value in the preoperative imaging diagnosis of lesions with FCD-IIa in epilepsy patients.

scholarly journals Three-Tesla Magnetic Resonance Imaging of Patients With Deep Brain Stimulators: Results From a Phantom Study and a Pilot Study in Patients

Neurosurgery ◽  
2020 ◽  
Author(s):  
Benjamin Davidson ◽  
Fred Tam ◽  
Benson Yang ◽  
Ying Meng ◽  
Clement Hamani ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Mri ◽  
Phantom Study ◽  
Voltage Amplitude ◽  
Resonance Imaging ◽  
Safety Testing ◽  
3T Mri ◽  
Activated State ◽  
Deep Brain

Abstract BACKGROUND Deep brain stimulation (DBS) is a standard of care treatment for multiple neurologic disorders. Although 3-tesla (3T) magnetic resonance imaging (MRI) has become the gold-standard modality for structural and functional imaging, most centers refrain from 3T imaging in patients with DBS devices in place because of safety concerns. 3T MRI could be used not only for structural imaging, but also for functional MRI to study the effects of DBS on neurocircuitry and optimize programming. OBJECTIVE To use an anthropomorphic phantom design to perform temperature and voltage safety testing on an activated DBS device during 3T imaging. METHODS An anthropomorphic 3D-printed human phantom was constructed and used to perform temperature and voltage testing on a DBS device during 3T MRI. Based on the phantom assessment, a cohort study was conducted in which 6 human patients underwent MRI with their DBS device in an activated (ON) state. RESULTS During the phantom study, temperature rises were under 2°C during all sequences, with the DBS in both the deactivated and activated states. Radiofrequency pulses from the MRI appeared to modulate the electrical discharge from the DBS, resulting in slight fluctuations of voltage amplitude. Six human subjects underwent MRI with their DBS in an activated state without any serious adverse events. One patient experienced stimulation-related side effects during T1-MPRAGE scanning with the DBS in an ON state because of radiofrequency-induced modulation of voltage amplitude. CONCLUSION Following careful phantom-based safety testing, 3T structural and functional MRI can be safely performed in subjects with activated deep brain stimulators.

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