Citations

PurposeTo investigate the effect of the asymmetric gradient concomitant fields (CF) with zeroth and first‐order spatial dependence on fast/turbo spin‐echo acquisitions, and to demonstrate the effectiveness of their real‐time compensation.MethodsAfter briefly reviewing the CF produced by asymmetric gradients, the effects of the additional zeroth and first‐order CFs on these systems are investigated using extended‐phase graph simulations. Phantom and in vivo experiments are performed to corroborate the simulation. Experiments are performed before and after the real‐time compensations using frequency tracking and gradient pre‐emphasis to demonstrate their effectiveness in correcting the additional CFs. The interaction between the CFs and prescan‐based correction to compensate for eddy currents is also investigated.ResultsIt is demonstrated that, unlike the second‐order CFs on conventional gradients, the additional zeroth/first‐order CFs on asymmetric gradients cause substantial signal loss and dark banding in fast spin‐echo acquisitions within a typical brain‐scan field of view. They can confound the prescan correction for eddy currents and degrade image quality. Performing real‐time compensation successfully eliminates the artifacts.ConclusionsWe demonstrate that the zeroth/first‐order CFs specific to asymmetric gradients can cause substantial artifacts, including signal loss and dark bands for brain imaging. These effects can be corrected using real‐time compensation. Magn Reson Med 79:1354–1364, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

708 Background: In June 2015 Cancer Care Ontario convened an expert panel to determine if there is an optimum LV dose in 5FU-LV combinations for the treatment of CRC. This request arose out of observed variation in LV dosages between some cancer centers. The research question was effect of LV dose on overall survival (OS), progression free survival (PFS), disease free survival (DFS), response rate (RR) and adverse events/toxicity, given a constant dose of 5FU. Methods: A systematic search was conducted for guidelines (GL) and comparative trials; eligibility included English language, with > 30 patients, that examined different doses of LV where dose of 5FU was not varied. Assessment of studies for inclusion was completed by 4 reviewers. Results: We identified 5 GL, 0 systematic reviews and 12 trials that defined a LV dose in combination with 5FU. None of the GL informed an optimal dose of LV. RR was assessed in 10 trials; 4 showed trends to higher RR with higher LV dose, but differences were not statistically significant (SS) between arms. PFS or DFS was reported in 6 trials and was similar between arms. Time to recurrence reported in one trial that included bevacizumab (BV) was longer in the high dose LV group that was SS. OS was addressed in 10 studies: no difference found in 7 studies; in one RCT OS was longer with the higher dose LV 55 vs. 45 months (p not reported); in one retrospective study OS was 23 vs. 20 months in favor of high dose LV (p not reported); one study of LV and BV had longer OS vs. lower dose LV at 26 vs. 21 months (SS). Toxicity: higher dose LV was associated with greater toxicity in 3 of 4 studies that reported stomatis, and increased rates of diarrhea in 9 of 11 trials. Meta-analysis was not appropriate as studies were too heterogeneous. Conclusions: There is no convincing evidence to identify an optimum dose of LV to be used in 5-FU/LV combinations. Amongst studies that did show a difference the trend was improved survival in favor of the higher dose. Similarly, differences in toxicities when identified were consistently greater with the higher dose LV. The expert panel concludes that the existing literature provides insufficient data to suggest that chemotherapy protocols should deviate from standard protocol doses.

ObjectiveThis study aims to provide effect size estimates of the impact of two cognitive rehabilitation interventions provided to patients with mild cognitive impairment: computerized brain fitness exercise and memory support system on support partners' outcomes of depression, anxiety, quality of life, and partner burden.MethodsA randomized controlled pilot trial was performed.ResultsAt 6 months, the partners from both treatment groups showed stable to improved depression and anxiety scores, while partners in an untreated control group showed worsening depression and anxiety over 6 months. There were no statistically significant differences on quality of life or burden outcomes in this small pilot trial; however, effect sizes were moderate, suggesting that the sample sizes in this pilot study were not adequate to detect statistical significance.ConclusionEither form of cognitive rehabilitation may help partners' mood or anxiety, compared with providing no treatment. However, effect size estimates related to other partner outcomes (i.e., burden, quality of life) suggest that follow‐up efficacy trials will need sample sizes of at least 30–100 people per group to accurately determine significance. Copyright © 2017 John Wiley & Sons, Ltd.

Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimated electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.8 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r = 0.86) and depth (r = 0.88) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials.

ObjectivePatients with probable dementia with Lewy bodies (DLB) often have Alzheimer's disease (AD)‐related pathology. Our objective was to determine the pattern of positron emission tomography (PET) tau tracer AV‐1451 uptake in patients with probable DLB, compared to AD, and its relationship to β‐amyloid deposition on PET.MethodsConsecutive patients with clinically probable DLB (n = 19) from the Mayo Clinic Alzheimer's Disease Research Center underwent magnetic resonance imaging, AV‐1451, and Pittsburgh compound‐B (PiB) PET examinations. Age‐ and sex‐matched groups of AD dementia (n = 19) patients and clinically normal controls (n = 95) from an epidemiological cohort served as a comparison groups. Atlas‐ and voxel‐based analyses were performed.ResultsThe AD dementia group had significantly higher AV‐1451 uptake than the probable DLB group, and medial temporal uptake completely distinguished AD dementia from probable DLB. Patients with probable DLB had greater AV‐1451 uptake in the posterior temporoparietal and occipital cortex compared to clinically normal controls, and in probable DLB, the uptake in these regions correlated with global cortical PiB uptake (Spearman rho = 0.63; p = 0.006).InterpretationMedial temporal lobe AV‐1451 uptake distinguishes AD dementia from probable DLB, which may be useful for differential diagnosis. Elevated posterior temporoparietal and occipital AV‐1451 uptake in probable DLB and its association with global cortical PiB uptake suggest an atypical pattern of tau deposition in DLB. ANN NEUROL 2017;81:58–67