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Background: Ultrahigh-field (UHF) MRI advances towards clinical use. Patient compliance is generally high, but few large-scale studies have investigated the effects experienced in 7T MRI systems, especially considering peripheral nerve stimulation (PNS) and caregiving., Purpose: To evaluate the quantity, the intensity, and subjective experiences from short-term effects, focusing on the levels of comfort and compliance of subjects., Study Type: Prospective., Population: In all, 954 consecutive MRIs in 801 subjects for 3 years., Field Strength: 7T., Assessment: After the 7T examination, a questionnaire was used to collect data., Statistical Tests: Descriptive statistics, Spearman's rank correlation, Mann-Whitney U-test, and t-test., Results: The majority (63%) of subjects agreed that the MRI experience was comfortable and 93% would be willing to undergo future 7T MRI as a patient (5% undecided) and 82% for research purposes (12% undecided). The most common short-term effects experienced were dizziness (81%), inconsistent movement (68%), PNS (63%), headache (40%), nausea (32%), metallic taste (12%), and light flashes (8%). Of the subjects who reported having PNS (n = 603), 44% experienced PNS as "not uncomfortable at all," 45% as "little or very little uncomfortable," and 11% as "moderate to very much uncomfortable." Scanner room temperature was experienced more comfortable before (78%) than during (58%) examinations, and the noise level was acceptable by 90% of subjects. Anxiety before the examination was reported by 43%. Patients differed from healthy volunteers regarding an experience of headache, metallic taste, dizziness, or anxiety. Room for improvement was pointed out after 117 examinations concerning given information (n = 73), communication and sound system (n = 35), or nursing care (n = 15)., Data Conclusion: Subjectively reported effects occur in actively shielded 7T MRI and include physiological responses and individual psychological issues. Although leaving room for improvement, few subjects experienced these effects being so uncomfortable that they would lead to aversion to future UHF examinations., Level of Evidence: 1 TECHNICAL EFFICACY: Stage 5 J. Magn. Reson. Imaging 2020;52:1265-1276., (© 2020 The Authors. Journal of Magnetic Resonance Imaging published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.)

Purpose: To investigate if resting-state functional MRI (fMRI) reliably can serve as a complement to task-based fMRI for presurgical mapping of the sensorimotor cortex., Materials and Methods: Functional data were obtained in 10 healthy volunteers using a 3 Tesla MRI system. Each subject performed five bilateral finger tapping experiments interleaved with five resting-state experiments. Following preprocessing, data from eight volunteers were further analyzed with the general linear model (finger tapping data) and independent component analysis (rest data). Test-retest reliability estimates (hit rate and false alarm rate) for resting-state fMRI activation of the sensorimotor network were compared with the reliability estimates for task-evoked activation of the sensorimotor cortex. The reliability estimates constituted a receiver operating characteristics curve from which the area under the curve (AUC) was calculated. Statistical testing was performed to compare the two groups with respect to reliability., Results: The AUC was generally higher for the task experiments, although median AUC was not significantly different on a group level. Also, the two groups showed comparable levels of within-group variance., Conclusion: Test-retest reliability was comparable between resting-state measurements and task-based fMRI, suggesting that presurgical mapping of functional networks can be a supplement to task-based fMRI in cases where patient status excludes task-based fMRI., (Copyright © 2011 Wiley-Liss, Inc.)

Purpose: To evaluate artifact sizes at 3 T compared to at 1.5 T, and to evaluate the influence of scanning parameters with respect to artifact size on a 3-T magnetic resonance imaging (MRI) system., Materials and Methods: Two aneurysm clips and five shunt valves were imaged in a water phantom at 1.5 and 3 T. At 3 T the influence of bandwidth (spin echo (SE) images) and echo time (gradient echo (GRE) images) on artifact size (area and extension in two orthogonal directions) was investigated., Results: Artifact sizes increased substantially (typically 5-10 mm) at 3 T, compared to at 1.5 T, for implants entirely made of metallic materials, whereas the increase was the size less prominent (0-5 mm) for implants only partly containing metal. Artifact areas could be altered by changing the bandwidth or the echo time to about the same extent as it was affected by the increased field strength., Conclusion: Artifact sizes increase at 3 T, compared to at 1.5 T, depending on the type and composition of the implant, but can be substantially reduced by altering the imaging parameters. Optimization of imaging protocols to minimize artifacts is therefore important at higher field strengths., ((c) 2005 Wiley-Liss, Inc.)

Magnetic resonance imaging (MRI) safety was evaluated at 1.5 T in a covered nickel titanium stent-graft (Vanguard) used for endovascular treatment of abdominal aortic aneurysms (AAAs). Imaging artifacts were assessed on MRI with contrast-enhanced (CE) three-dimensional (3D) MR angiography (MRA) and spiral computed tomography (CT) in 10 patients as well as ex vivo. Velocity mapping was performed in the suprarenal aorta and femoral arteries in 14 patients before and after stent-graft placement. For comparison it was also performed in six healthy volunteers. No ferromagnetism or heating was detected. Metal artifacts caused minimal image distortion on MRI/MRA. The artifacts disturbed image evaluation on CT at the graft bifurcation and graft limb junction. No significant differences in mean flow were found in patients before and after stent-graft placement. Our study indicates that MRI at 1.5 T may be performed safely in patients with the (Vanguard) stent-graft. MRI/MRA provides diagnostic image information. Velocity mapping is not included in our routine protocol.