The hippocampus is a key component of emotional and memory circuits broadly connected throughout the brain. We tracked whole-brain connections white matter fibres from using ultra-high angular resolution diffusion MRI in both single 1150-direction dataset large normal cohort (n = 94; 391-directions). Using connectomic approach, we identified six dominant pathways terms strength, length anatomy, characterised them by their age gender variation. strongest individual connection was to...

Pancreatic diffusion-weighted imaging (DWI) has numerous clinical applications, but conventional single-shot methods suffer from off resonance-induced artifacts like distortion and blurring while cardiovascular motion-induced phase inconsistency leads to quantitative errors signal loss, limiting its utility. Multishot DWI (msDWI) offers reduced image relative increases sensitivity motion artifacts. Motion-compensated diffusion-encoding gradients (MCGs) reduce could improve robustness of...

Simultaneous Multi-Slice (SMS) magnetic resonance imaging (MRI) is a rapidly evolving technique for increasing speed. Controlled aliasing techniques utilize periodic undersampling patterns to help mitigate the loss in signal-to-noise ratio (SNR) SMS MRI. To evaluate performance of different patterns, quantitative description image SNR needed. Additionally, eddy current effects echo planar (EPI) lead slice-specific Nyquist ghosting artifacts. These artifacts cannot be accurately corrected...

Purpose To develop and validate a deep learning‐based reconstruction framework for highly accelerated two‐dimensional (2D) phase contrast (PC‐MRI) data with accurate precise quantitative measurements. Methods We propose modified DL‐ESPIRiT 2D PC‐MRI, comprised of an unrolled neural network architecture Complex Difference estimation (CD‐DL). CD‐DL was trained on 155 fully sampled PC‐MRI pediatric clinical datasets. The () retrospectively undersampled (6–11) reconstructed using parallel...

Abstract Phase‐contrast magnetic resonance imaging is subject to numerous sources of error, which decrease clinical confidence in the reported measures. This work outlines how stationary perivascular fat can impart a significant chemical shift induced phase‐contrast measurement error using computational simulations, vitro, and vivo experiments. does not subtract phase difference processing, but be minimized with proper parameter selection. The errors largely depend on both receiver bandwidth...

Diffusion MRI (dMRI) tractography is a uniquely powerful tool capable of demonstrating structural brain network abnormalities across range psychiatric disorders; however, it not currently clinically useful. This because limitations on sensitivity effectively restrict its application to scientific studies cohorts, rather than individual patients. Recent improvements in dMRI hardware, acquisition, processing and analysis techniques may, overcome these measurement limitations. We therefore...

The development and implementation of novel MRI pulse sequences remains challenging laborious. Gradient waveforms are typically designed using a combination analytical ad hoc methods to construct each gradient waveform axis independently. This strategy makes coding the sequence complicated, in addition being time inefficient. As consequence, nearly all commercial fail maximize use available hardware or efficiently mitigate physiological effects. results expensive systems that underperform...

Purpose To evaluate convex gradient optimization (CVX) for increased spatiotemporal resolution and improved accuracy phase‐contrast MRI (PC‐MRI). Methods A conventional flow‐compensated flow‐encoded (FCFE) PC‐MRI sequence was compared with a CVX using numerical simulations, flow phantom experiments, in vivo experiments. Flow measurements within the ascending aorta, main pulmonary artery, right/left arteries of normal volunteers (N = 10) were acquired at 3T analyzed FCFE either higher spatial...

Purpose To introduce and demonstrate a software library for time‐optimal gradient waveform optimization with wide range of applications. The enables direct on‐the‐fly design on the scanner hardware multiple vendors. Methods open‐source (GrOpt) toolbox was implemented in C both Matlab Python wrappers. waveforms to be generated based set constraints that define features encodings given acquisition. GrOpt routine is alternating direction method multipliers (ADMM). Additional enable error...

Purpose To investigate a novel phase‐contrast MRI velocity‐encoding technique for faster imaging and reduced chemical shift‐induced phase errors. Methods Velocity encoding with the slice select refocusing gradient achieves target moment by time shifting gradient, which enables use of minimum in‐phase echo (TE) Net forward flow was compared in 10 healthy subjects ( N = 10) within ascending aorta (aAo), main pulmonary artery (PA), right/left arteries (RPA/LPA) using conventional compensated...

Purpose To develop and evaluate a technique for accelerating phase contrast MRI (PC‐MRI) acquisitions without significant compromise in flow quantification accuracy. Methods PC‐MRI is commonly acquired using interleaved flow‐compensated (FC) flow‐encoded (FE) echoes. We hypothesized that FC data, which represent background phase, do not change significantly over time. Therefore, we proposed to undersample the data use an view sharing (FCVS) approach synthesize composite frame each...

To evaluate the use of pre-excitation gradients for eddy current-nulled convex optimized diffusion encoding (Pre-ENCODE) to mitigate current-induced image distortions in diffusion-weighted MRI (DWI).

Multi-shot DWI (msDWI) may be improved by M1 motion-compensation, but at a penalty of longer TE and lower SNR. DL-based denoising has recently emerged as an option for DWI, which could help offset this penalty. Here we assess the impact commercially available tool in setting motion-compensated msDWI.

Diffusion encoding gradients produce eddy currents that cause image distortions in DWI. Twice refocused spin-echo (TRSE) and current-nulled convex optimized diffusion (ENCODE) mitigate current-induced DWI, but at the expense of extending TE. Herein, we revise original ENCODE method by playing additional pre-excitation gradient lobes (Pre-ENCODE). Using simulations, phantom experiments, vivo imaging demonstrate Pre-ENCODE mitigates DWI with a shorter TE than TRSE ENCODE.

Multi-shot DWI reduces image distortion while increasing SNR. More recently, motion-compensated diffusion encoding has been shown to reduce artifacts and improve ADC consistency in single-shot DWI. Motion-compensated multi-shot pancreatic may also mitigate arising from shot-to-shot incoherence. Herein, we conducted a pilot study of the pancreas with without encoding. Image quality were scored by expert radiologists. values different anatomical segments computed. gradient increased...

We propose a physics-driven approach for prediction of eddy current-induced background phase offsets in 2D PC-MRI. The method leverages the applied gradient waveforms and circuit model to estimate system-dependent parameters that govern phase. aim is use these predict clinical acquisitions from pulse sequence information only. Our achieved an RMSE 1.05 cm/s adequate visual quality.

We have previously trained a deep learning-based (DL) reconstruction for 2D PC-MRI using fully-sampled (n=194) raw k-space pediatric datasets. This DL-based provided up to 9x undersampling with ≤5% error in accuracy and precision of peak velocity total flow. Herein, we analyze this adult volunteers (n=3) patients (n=8) show that our provides ~5% flow 7x undersampling.

The objective of this work was to control the total number collected diffusion weighted images (DWI) across several different acquisition schemes evaluate which combination directions and averages provides highest quality data. In vivo cDTI data in volunteers (N=5) using a series fixed duration protocols that span range signal averages. We found balancing (12-20) (5-3) allows for robust quantification mean diffusivity, fractional anisotropy, helix measurements scan time.

Diffusion-Weighted Imaging (DWI) allows for the detection of breast cancer without a contrast injection, while supine positioning may improve comfort and efficiency MRI screening exam. This work investigates multi-shot DWI breasts in versus prone positions, both asymptomatic volunteers patients with lesions. Supine outperformed based on an image quality observer study, receiving significantly higher ratings sharpness, aliasing, overall quality. Lesion Apparent Diffusion Coefficients (ADCs)...

Motivation: Eddy current-induced image distortions in DWI require either tedious image-based corrections or time inefficient pulse sequence acquisitions that increase the minimum echo (TEmin) and limit SNR. Goal(s): Pre-excitation gradients for eddy current-nulled convex optimized diffusion encoding (Pre-ENCODE) was used to mitigate without increasing TEmin. Approach: Simulations, phantoms, volunteer with monopolar (MONO), (ENCODE), Pre-ENCODE were evaluate TEmin, distortions, ADC. Results:...

Assessment of microcirculation is extremely important in skeletal muscle aging reasearch. While IVIM can provide valuable information on perfusion, this usually dominated by flow larger vessel, resulting limited sensitivity to microcirculation. In study we propose the use and non-flow-compensated diffusion encoding waveforms for muscle. Using approach show diffrences parameters between younger older adults, correlation difference age