Novel inductively coupled ear-bars (ICEs) to enhance restored fMRI signal from susceptibility compensation in rats

Abstract

Functional magnetic resonance imaging faces inherent challenges when applied to deep-brain areas in rodents, e.g. entorhinal cortex, due to the signal loss near the ear cavities induced by susceptibility artifacts and reduced sensitivity induced by the long distance from the surface array coil. Given the pivotal roles of deep brain regions in various diseases, optimized imaging techniques are needed. To mitigate susceptibility-induced signal losses, we introduced baby cream into the middle ear. To enhance the detection sensitivity of deep brain regions, we implemented inductively coupled ear-bars, resulting in approximately a 2-fold increase in sensitivity in entorhinal cortex. Notably, the inductively coupled ear-bar can be seamlessly integrated as an add-on device, without necessitating modifications to the scanner interface. To underscore the versatility of inductively coupled ear-bars, we conducted echo-planner imaging-based task functional magnetic resonance imaging in rats modeling Alzheimer’s disease. As a proof of concept, we also demonstrated resting-state-functional magnetic resonance imaging connectivity maps originating from the left entorhinal cortex—a central hub for memory and navigation networks-to amygdala hippocampal area, Insular Cortex, Prelimbic Systems, Cingulate Cortex, Secondary Visual Cortex, and Motor Cortex. This work demonstrates an optimized procedure for acquiring large-scale networks emanating from a previously challenging seed region by conventional magnetic resonance imaging detectors, thereby facilitating improved observation of functional magnetic resonance imaging outcomes.

A novel hybrid Wireless Integrated Sensing Detector for simultaneous EEG and MRI (WISDEM)

“…After the amplified images were aligned with the standard SIGMA brain atlas 67 , we calculated the correlation coefficient between the timedependent signal intensity of each pixel and the ideal stimulation function, thus identifying brain regions that were activated by forepaw stimulation. As shown in the color-coded activation map (Fig 4c) overlapped on the atlas 67 , the S1FP region had a BOLD modulation pattern with the same periodicity (15 s) as the stimulation epoch, which was highly consistent with previous results [68][69][70] using conventional surface coils. Within each epoch, the MR signal intensity had up to 1.5% modulation during the 4-s stimulation period before returning to the baseline level.…”