Jonathan R Polimeni

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Verified

Jonathan verified their affiliation via an institutional email.

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• Ph.D.
• Professor (Associate) at Stanford University

Sleep entails significant changes in cerebral hemodynamics and metabolism. Yet, the way these processes evolve throughout wakefulness and sleep and their spatiotemporal dependence remain largely unknown. Here, by integrating a novel functional PET technique with simultaneous EEG-fMRI, we reveal a tightly coupled temporal progression of global hemod...

In functional magnetic resonance imaging (fMRI), neural activity is inferred from the associated hemodynamic response. However, the degree to which hemodynamics can track dynamic changes in neuronal activity, and thus the ultimate temporal resolution of fMRI, remains unknown. To evaluate the detectability of stimulus-driven high-frequency blood oxy...

In graph theory, “multilayer networks” represent systems involving several interconnected topological levels. One example in neuroscience is the stratification of connections between different cortical depths or “laminae,” which is becoming noninvasively accessible in humans using ultrahigh-resolution functional MRI (fMRI). Here, we applied a multi...

Over the past two decades, rapid advancements in magnetic resonance technology have significantly enhanced the imaging resolution of functional Magnetic Resonance Imaging (fMRI), far surpassing its initial capabilities. Beyond mapping brain functional architecture at unprecedented scales, high-spatial-resolution acquisitions have also inspired and...

The ability to detect fast responses with functional MRI depends on the speed of hemodynamic responses to neural activity, because hemodynamic responses act as a temporal low-pass filter which blurs rapid changes. However, the shape and timing of hemodynamic responses are highly variable across the brain and across stimuli. This heterogeneity of re...

Purpose To overcome the major challenges in diffusion MRI (dMRI) acquisition, including limited SNR, distortion/blurring, and susceptibility to motion artifacts. Theory and Methods A novel Romer‐EPTI technique is developed to achieve SNR‐efficient acquisition while providing distortion‐free imaging, minimal spatial blurring, high motion robustness...

Functional Positron Emission Tomography (fPET) with (bolus plus) constant infusion of [18F]-fluorodeoxyglucose FDG), known as fPET-FDG, is a recently introduced technique in human neuroimaging, enabling the detection of dynamic glucose metabolism changes within a single scan. However, the statistical analysis of fPET-FDG data remains challenging be...

Purpose To develop a single‐shot SNR‐efficient distortion‐free multi‐echo imaging technique for dynamic imaging applications. Methods Echo planar time‐resolved imaging (EPTI) was first introduced as a multi‐shot technique for distortion‐free multi‐echo imaging. This work aims to develop single‐shot EPTI (ss‐EPTI) to achieve improved robustness to...

Macrovascular biases have been a long-standing challenge for functional magnetic resonance imaging (fMRI), limiting its ability to detect spatially specific neural activity. Recent experimental studies, including our own, found substantial resting-state macrovascular blood-oxygenation level-dependent (BOLD) fMRI contributions from large veins and a...

Purpose Echo planar time‐resolved imaging (EPTI) is a new imaging approach that addresses the limitations of EPI by providing high‐resolution, distortion‐ and T2/T2*$$ {\mathrm{T}}_2^{\ast } $$ blurring–free imaging for functional MRI (fMRI). However, as in all multishot sequences, intershot phase variations induced by physiological processes can i...

Advances in the spatiotemporal resolution and field-of-view of neuroimaging tools are driving mesoscale studies for translational neuroscience. On October 10, 2023, the Center for Mesoscale Mapping (CMM) at the Massachusetts General Hospital (MGH) Athinoula A. Martinos Center for Biomedical Imaging and the Massachusetts Institute of Technology (MIT...

Magnetic resonance angiography (MRA) performed at ultra-high magnetic field provides a unique opportunity to study the arteries of the living human brain at the mesoscopic level. From this, we can gain new insights into the brain's blood supply and vascular disease affecting small vessels. However, for quantitative characterization and precise repr...

Magnetic resonance angiography (MRA) performed at ultra-high magnetic field provides a unique opportunity to study the arteries of the living human brain at the mesoscopic level. From this, we can gain new insights into the brain's blood supply and vascular disease affecting small vessels. However, for quantitative characterization and precise repr...

United States (US) Special Operations Forces (SOF) are frequently exposed to explosive blasts in training and combat, but the effects of repeated blast exposure (RBE) on SOF brain health are incompletely understood. Furthermore, there is no diagnostic test to detect brain injury from RBE. As a result, SOF personnel may experience cognitive, physica...

Macrovascular biases have been a long-standing challenge for fMRI, limiting its ability to detect spatially specific neural activity. Recent experimental studies, including our own (Huck et al., 2023; Zhong et al., 2023), found substantial resting-state macrovascular BOLD fMRI contributions from large veins and arteries, extending into the perivasc...

The ability to detect fast responses with functional MRI depends on the speed of hemodynamic responses to neural activity, because hemodynamic responses act as a temporal low-pass filter smoothing out rapid changes. However, hemodynamic responses (their shape and timing) are highly variable across the brain and across stimuli. This heterogeneity of...

Background: Previous case reports suggested co-localization of tau but not β-Amyloid with cortical superficial siderosis (cSS) in cerebral amyloid angiopathy (CAA). We thus hypothesized that the tau load represents a continuum with amyloid accumulation in the disease cascade and that the tau load would be higher in lobes with cSS and intracerebral...

Purpose: To overcome the major challenges in diffusion MRI acquisition, including low SNR, distortion/blurring, and motion vulnerability. Methods: A novel Romer-EPTI technique is developed to provide high SNR, sharp spatial resolution, high motion-robustness, images free from distortion and slab-boundary artifacts, and simultaneous multi-TE imaging...

Purpose: To develop EPTI, a multi-shot distortion-free multi-echo imaging technique, into a single-shot acquisition to achieve improved robustness to motion and physiological noise, increased temporal resolution, and high SNR efficiency for dynamic imaging applications. Methods: A new spatiotemporal encoding was developed to achieve single-shot EPT...

Neuroimaging studies of the functional organization of human auditory cortex have focused on group-level analyses to identify tendencies that represent the typical brain. Here, we mapped auditory areas of the human superior temporal cortex (STC) in 30 participants by combining functional network analysis and 1-mm isotropic resolution 7T functional...

In graph theory, "multilayer networks" represent systems involving several interconnected topological levels. A neuroscience example is the hierarchy of connections between different cortical depths or "lamina". This hierarchy is becoming non-invasively accessible in humans using ultra-high-resolution functional MRI (fMRI). Here, we applied multila...

To increase granularity in human neuroimaging science, we designed and built a next-generation 7 Tesla magnetic resonance imaging scanner to reach ultra-high resolution by implementing several advances in hardware. To improve spatial encoding and increase the image signal-to-noise ratio, we developed a head-only asymmetric gradient coil (200 mT m⁻¹...

United States Special Operations Forces (SOF) personnel are frequently exposed to explosive blasts in training and combat. However, the effects of repeated blast exposure on the human brain are incompletely understood. Moreover, there is currently no diagnostic test to detect repeated blast brain injury (rBBI). In this "Human Performance Optimizati...

Speech and language processing involve complex interactions between cortical areas necessary for articulatory movements and auditory perception and a range of areas through which these are connected and interact. Despite their fundamental importance, the precise mechanisms underlying these processes are not fully elucidated. We measured BOLD signal...

In this editorial we introduce a new non-profit open access journal, Imaging Neuroscience. In April 2023, editors of the journals NeuroImage and NeuroImage:Reports resigned, and a month later launched Imaging Neuroscience. NeuroImage had long been the leading journal in the field of neuroimaging. While the move to fully open access in 2020 represen...

BACKGROUND: The association between brain regions involved in speech production and those that play a role in speech perception is not yet fully understood. We compared speech production related brain activity with activations resulting from perceptual categorization of syllables using high field 7 Tesla functional magnetic resonance imaging (fMRI)...

Diffusion MRI is a useful neuroimaging tool for non-invasive mapping of human brain microstructure and structural connections. The analysis of diffusion MRI data often requires brain segmentation, including volumetric segmentation and cerebral cortical surfaces, from additional high-resolution T1-weighted (T1w) anatomical MRI data, which may be una...

Background Cerebral Amyloid Angiopathy (CAA) is a cerebral small vessel disease that can lead to microstructural disruption of white matter (WM), which can be measured by the Peak Width of Skeletonized Mean Diffusivity (PSMD). We hypothesized that PSMD measures would be increased in patients with CAA compared to healthy controls (HC), and increased...

The characterization of cortical myelination is essential for the study of structure-function relationships in the human brain. However, knowledge about cortical myelination is largely based on post-mortem histology, which generally renders direct comparison to function impossible. The repeating pattern of pale-thin-pale-thick stripes of cytochrome...

Background and Purpose: We aimed to compare the amyloid load and degree of microstructural injury among Cerebral Amyloid Angiopathy (CAA) patients with either higher lobar cerebral microbleed (CMB) counts or higher cortical superficial siderosis (cSS) extent against CAA patients with lower hemorrhagic load. Methods: The study included 38 cognitivel...

Purpose To achieve high‐resolution multishot echo‐planar imaging (EPI) for functional MRI (fMRI) with reduced sensitivity to in‐plane motion and between‐shot phase variations. Methods Two‐dimensional radiofrequency pulses were incorporated in a multishot EPI sequence at 7T which selectively excited a set of in‐plane bands (shutters) in the phase e...

Brain motion interferes with functional magnetic resonance imaging (fMRI) by causing a variety of signal artifacts whose characteristics depend on the kind of motion, the pulse sequence used, and when and how the motion occurred. In task fMRI, motion artifact uncorrelated with the task design degrades statistical power by introducing noise, causing...

Neural network (NN) based approaches for super-resolution MRI typically require high-SNR high-resolution reference data acquired in many subjects, which is time consuming and a barrier to feasible and accessible implementation. We propose to train NNs for Super-Resolution using Noisy Reference data (SRNR), leveraging the mechanism of the classic NN...

T1 relaxation times of the 14 T1 phantom spheres that make up the standard ISMRM/NIST system phantom are being reported at 7 T. T1 values of six out of the 14 T1 spheres at 7 T (with T1 > 270 ms) have been reported previously but to the best of our knowledge, not all the T1s of the 14 T1 spheres at 7 T have been reported before. Given the increasin...

Accurate spatial alignment of MRI data acquired across multiple contrasts in the same subject is often crucial for data analysis and interpretation, but can be challenging in the presence of geometric distortions that differ between acquisitions. It is well known that single-shot echo-planar imaging (EPI) acquisitions suffer from distortion in the...

Awakening from sleep reflects a profound transformation in neural activity and behavior. The thalamus is a key controller of arousal state, but whether its diverse nuclei exhibit coordinated or distinct activity at transitions in behavioral arousal state is unknown. Using fast fMRI at ultra-high field (7 Tesla), we measured sub-second activity acro...

Purpose To implement a method for real‐time field control using rapid FID navigator (FIDnav) measurements and evaluate the efficacy of the proposed approach for mitigating dynamic field perturbations and improving T2*$$ {\mathrm{T}}_2^{\ast } $$‐weighted image quality. Methods FIDnavs were embedded in a gradient echo sequence and a subject‐specifi...

Invasive neurophysiological studies in nonhuman primates have shown different laminar activation profiles to auditory vs. visual stimuli in auditory cortices and adjacent polymodal areas. Means to examine the underlying feedforward vs. feedback type influences noninvasively have been limited in humans. Here, using 1‐mm isotropic resolution 3D echo‐...

White matter lesions (WML) have been linked to cognitive decline in aging as well as in Alzheimer’s disease. While hypoperfusion is frequently considered a cause of WMLs due to the resulting reduction in oxygen availability to brain tissue, such reductions could also be caused by impaired oxygen exchange. Here, we tested the hypothesis that venous...

Recent studies have reported functional MRI (fMRI) activation within cerebral white matter (WM) using blood-oxygenation-level-dependent (BOLD) contrast. Many blood vessels in WM run parallel to the fibre bundles, and other studies observed dependence of susceptibility contrast-based measures of blood volume on the local orientation of the fibre bun...

Emerging evidence suggests that repeated blast exposure (RBE) is associated with brain injury in military personnel. United States (U.S.) Special Operations Forces (SOF) personnel experience high rates of blast exposure during training and combat, but the effects of low-level RBE on brain structure and function in SOF have not been comprehensively...

Objective: Recent data suggest that cerebral amyloid angiopathy (CAA) causes haemorrhagic lesions in cerebellar cortex as well as subcortical cerebral atrophy. However, the potential effect of CAA on cerebellar tissue loss and its clinical implications have not been investigated. Methods: Our study included 70 non-demented patients with probable...

The pial arterial vasculature of the human brain is the only blood supply to the neocortex, but quantitative data on the morphology and topology of these mesoscopic arteries (diameter 50-300µm) remains scarce. Because it is commonly assumed that blood flow velocities in these vessels are prohibitively slow, non-invasive time-of-flight MRI angiograp...

The characterization of cortical myelination is essential for the study of structure-function relationships in the human brain. However, knowledge about cortical myelination is largely based on post mortem histology, which shows conflicting results depending on the staining method used, and generally renders direct comparison to function impossible...

Ultra‐high Field (≥7T) functional magnetic resonance imaging (UHF‐fMRI) provides opportunities to resolve fine‐scale features of functional architecture such as cerebral cortical columns and layers, in vivo. While the nominal resolution of modern fMRI acquisitions may appear to be sufficient to resolve these features, several common data preprocess...

Understanding how and why MR signals and their associated relaxation rates vary with cortical depth could ultimately enable the noninvasive investigation of the laminar architecture of cerebral cortex in the living human brain. However, cortical gray matter is typically only a few millimeters thick, making it challenging to sample many cortical dep...

Diffusion tensor magnetic resonance imaging (DTI) is a widely adopted neuroimaging method for the in vivo mapping of brain tissue microstructure and white matter tracts. Nonetheless, the noise in the diffusion-weighted images (DWIs) decreases the accuracy and precision of DTI derived microstructural parameters and leads to prolonged acquisition tim...

Background: Cerebral amyloid angiopathy (CAA) causes impaired vascular reactivity to physiologic stimuli that mediates CAA-related white matter hyperintensities (WMH) but its relationship to microstructural changes has not yet been tested. We hypothesized that the degree of vascular dysfunction would be associated with alterations in white matter m...

We postulated that vascular dysfunction mediates the relationship between amyloid load and white matter hyperintensities (WMH) in cerebral amyloid angiopathy (CAA). Thirty-eight cognitively healthy patients with CAA (mean age 70 ± 7.1) were evaluated. WMH was quantified and expressed as percent of total intracranial volume (pWMH) using structural M...

Strong gradient systems can improve the signal-to-noise ratio of diffusion MRI measurements and enable a wider range of acquisition parameters that are beneficial for microstructural imaging. We present a comprehensive diffusion MRI dataset of 26 healthy participants acquired on the MGH-USC 3 T Connectome scanner equipped with 300 mT/m maximum grad...

Accurate spatial alignment of MRI data acquired across multiple contrasts in the same subject is often crucial for data analysis and interpretation, but can be challenging in the presence of geometric distortions that differ between acquisitions. It is well known that single-shot echo-planar imaging (EPI) acquisitions suffer from distortion in the...

The moment of awakening from sleep reflects a profound transformation in neural activity and behavior. The thalamus is a key controller of arousal state, but whether its diverse nuclei exhibit coordinated or distinct activity at transitions in behavioral arousal state is not known. Using fast fMRI at ultra-high field (7 Tesla), we measured sub-seco...

The noise in diffusion-weighted images (DWIs) decreases the accuracy and precision of diffusion tensor magnetic resonance imaging (DTI) derived microstructural parameters and leads to prolonged acquisition time for achieving improved signal-to-noise ratio (SNR). Deep learning-based image denoising using convolutional neural networks (CNNs) has supe...

We tested how a stimulus gestalt, defined by the neuronal interaction between local and global features of a stimulus, is represented within human primary visual cortex (V1). We used high-resolution fMRI, which serves as a surrogate of neuronal activation, to measure co-fluctuations within subregions of V1 as (male and female) subjects were present...

Purpose To test an integrated “AC/DC” array approach at 7T, where B0 inhomogeneity poses an obstacle for functional imaging, diffusion‐weighted MRI, MR spectroscopy, and other applications. Methods A close‐fitting 7T 31‐channel (31‐ch) brain array was constructed and tested using combined Rx and ΔB0 shim channels driven by a set of rapidly switcha...

Spin-echo (SE) BOLD fMRI has high microvascular specificity, and thus provides a more reliable means to localize neural activity compared to conventional gradient-echo BOLD fMRI. However, the most common SE BOLD acquisition method, SE-EPI, is known to suffer from T2′ contrast contamination with undesirable draining vein bias. To address this, in th...

Recent studies have demonstrated that fast fMRI can track neural activity well above the temporal limit predicted by the canonical hemodynamic response model. While these findings are promising, the biophysical mechanisms underlying these fast fMRI phenomena remain underexplored. In this study, we discuss two aspects of the hemodynamic response, co...

The pial arterial vasculature of the human brain is the only blood supply to the neocortex, but quantitative data on the morphology and topology of these mesoscopic arteries (diameter 50–300 µm) remains scarce. Because it is commonly assumed that blood flow velocities in these vessels are prohibitively slow, non-invasive time-of-flight magnetic res...

Fast fMRI enables the detection of neural dynamics over timescales of hundreds of milliseconds, suggesting it may provide a new avenue for studying subsecond neural processes in the human brain. The magnitudes of these fast fMRI dynamics are far greater than predicted by canonical models of the hemodynamic response. Several studies have established...

Limited detection power has been a bottleneck for subject-specific functional MRI (fMRI) studies; however, the higher signal-to-noise ratio afforded by ultra-high magnetic fields (≥7 Tesla) provides levels of sensitivity and resolution needed to study individual subjects. What may be surprising is that higher imaging resolution may provide both hig...

Background and purpose: Age-related macular degeneration is associated with reduced perfusion of the eye; however, the role of altered blood flow in the upstream ophthalmic or internal carotid arteries is unclear. We used ultra-high-field MR imaging to investigate whether the diameter of and blood flow in the ophthalmic artery and/or the ICA are a...

The pial arterial vasculature of the human brain is the only blood supply to the neocortex, but quantitative data on the morphology and topology of these mesoscopic vessels (diameter 50-300 μm) remains scarce. Because it is commonly assumed that blood flow velocities in these vessels are prohibitively slow, non-invasive time-of-flight MRI angiograp...

Spin-echo (SE) BOLD fMRI has high microvascular specificity, but its most common acquisition method, SE-EPI, suffers from T2' contrast contamination with undesirable draining vein bias. To address this, in this study, we extended a recently developed multi-shot EPI technique, Echo-Planar Time-resolved Imaging (EPTI), to laminar SE-fMRI at 7T to obt...

We present a whole-brain in vivo diffusion MRI (dMRI) dataset acquired at 760 μm isotropic resolution and sampled at 1260 q-space points across 9 two-hour sessions on a single healthy participant. The creation of this benchmark dataset is possible through the synergistic use of advanced acquisition hardware and software including the high-gradient-...

Purpose Most voxels in white matter contain multiple fiber populations with different orientations and levels of myelination. Conventional T1 mapping measures 1 T1 value per voxel, representing a weighted average of the multiple tract T1 times. Inversion‐recovery diffusion‐weighted imaging (IR‐DWI) allows the T1 times of multiple tracts in a voxel...

Background: We hypothesized that Peak Width of Skeletonized Mean Diffusivity (PSMD), an automated marker of cerebral microangiopathy representing microstructural disruption of white matter (WM), would be increased in patients with cerebral amyloid angiopathy (CAA) compared to healthy controls (HCs) and increased PSMD would be associated with lower...

Background: Cerebral amyloid angiopathy (CAA) is associated with white matter hyperintensities (WMH) but the physiopathological mechanisms remain unclear. We hypothesized that the relationship between vascular amyloid load and WMH is mediated by vascular dysfunction. Methods: The study cohort included 38 non-demented probable CAA patients who under...

Background: The mechanisms linking cerebral amyloid angiopathy (CAA) to enlarged perivascular spaces in centrum semiovale (CSO-EPVS) and whether other Alzheimer’s Disease (AD) pathologies might affect CSO-EPVS are unclear. We hypothesized that amyloid but not tau load would independently correlate with CSO-EPVS in CAA. Methods: Fifty prospectively...

Automatic cerebral cortical surface reconstruction is a useful tool for cortical anatomy quantification, analysis and visualization. Recently, the Human Connectome Project and several studies have shown the advantages of using T1-weighted magnetic resonance (MR) images with sub-millimeter isotropic spatial resolution instead of the standard 1-milli...

Background: Recent data show that cerebral amyloid angiopathy (CAA) might cause hemorrhagic lesions in cerebellar cortex as well as cerebral atrophy. However, the potential effect of CAA on cerebellar tissue loss and its clinical implications have not been investigated. Methods: We compared cerebellar volumes in 70 nondemented patients with probabl...

High-resolution diffusion tensor imaging (DTI) is beneficial for probing tissue microstructure in fine neuroanatomical structures, but long scan times and limited signal-to-noise ratio pose significant barriers to acquiring DTI at sub-millimeter resolution. To address this challenge, we propose a deep learning-based super-resolution method entitled...

Objective: We aimed to analyze the relationship of lacunes with cortical cerebral microinfarcts (CMI), to assess their association with vascular dysfunction and to evaluate their effect on the risk of incident intracerebral hemorrhage (ICH) in cerebral amyloid angiopathy (CAA). Methods: The count and topography of lacunes (deep/lobar), CMIs and...

Recent developments in optical microscopy, applicable for large-scale and longitudinal imaging of cortical activity in behaving animals, open unprecedented opportunities to gain a deeper understanding of neurovascular and neurometabolic coupling during different brain states. Future studies will leverage these tools to deliver foundational knowledg...

Functional MRI (fMRI) represents a key application of neuroimaging at ultra-high field strengths, because the dramatic increase in fMRI sensitivity with field strength enables new classes of experiments not possible at conventional field strengths. Recent insights indicate that, although fMRI tracks neural activity indirectly through measuring the...

Identifying a structural brain lesion on MRI has important implications in epilepsy and is the most important correlate to seizure freedom after surgery in patients with drug-resistant focal onset epilepsy. However, at conventional magnetic field strengths (1.5 and 3T) only around 60-85% of MRI examinations reveal such lesions. Over the last decade...

The fMRI community has made great strides in decoupling neuronal activity from other physiologically induced T2* changes, using sensors that provide a ground-truth with respect to cardiac, respiratory, and head movement dynamics. However, blood oxygenation level-dependent (BOLD) time-series dynamics are also confounded by scanner artifacts, in comp...

We present a whole-brain in vivo diffusion MRI (dMRI) dataset acquired at 760 μm isotropic resolution and sampled at 1260 q-space points across 9 two-hour sessions on a single healthy subject. The creation of this benchmark dataset is possible through the synergistic use of advanced acquisition hardware and software including the high-gradient-stre...

Purpose To develop a method for slice‐wise dynamic distortion correction for EPI using rapid spatiotemporal B0 field measurements from FID navigators (FIDnavs) and to evaluate the efficacy of this new approach relative to an established data‐driven technique. Methods A low‐resolution reference image was used to create a forward model of FIDnav sig...

Automatic cerebral cortical surface reconstruction is a useful tool for cortical anatomy quantification, analysis and visualization. Recently, the Human Connectome Project and several studies have shown the advantages of using T 1 -weighted magnetic resonance (MR) images with sub-millimeter isotropic spatial resolution instead of the standard 1-mil...

Accurate and automated reconstruction of the in vivo human cerebral cortical surface from anatomical magnetic resonance (MR) images facilitates the quantitative analysis of cortical structure. Anatomical MR images with sub-millimeter isotropic spatial resolution improve the accuracy of cortical surface and thickness estimation compared to the stand...

Purpose The goal of this study was to measure diffusion signals within the cerebral cortex using the line‐scan technique to achieve extremely high resolution in the radial direction (ie, perpendicular to the cortical surface) and to demonstrate the utility of these measurements for investigating laminar architecture in the living human brain. Meth...

We demonstrate that non-rigid deformations of, e.g., the mouth introduce bias in the vNav-based detection of brain motion, which causes artifacts. We present real-time brain extraction for vNavs and show that these artifacts can be removed by brain-masked registration.

Purpose To alleviate the spatial encoding limitations of single‐shot echo‐planar imaging (EPI) by developing multi‐shot segmented EPI for ultra‐high‐resolution functional MRI (fMRI) with reduced ghosting artifacts from subject motion and respiration. Theory and Methods Segmented EPI can reduce readout duration and reduce acceleration factors, howe...

Purpose To alleviate the spatial encoding limitations of single-shot EPI by developing multi-shot segmented EPI for ultra-high-resolution fMRI with reduced ghosting artifacts from subject motion and respiration. Methods Segmented EPI can reduce readout duration and reduce acceleration factors, however, the time elapsed between segment acquisitions...