A 3D dual-echo spiral sequence for simultaneous dynamic susceptibility contrast and dynamic contrast-enhanced MRI with single bolus injection.

Purpose: Perfusion MRI reveals important tumor physiological and pathophysiologic information, making it a critical component in managing brain tumor patients. This study aimed to develop a dual-echo 3D spiral technique with a single-bolus scheme to simultaneously acquire both dynamic susceptibility contrast (DSC) and dynamic contrast-enhanced (DCE) data and overcome the limitations of current EPI-based techniques.

Methods: A 3D spiral-based technique with dual-echo acquisition was implemented and optimized on a 3T MRI scanner with a spiral staircase trajectory and through-plane SENSE acceleration for improved speed and image quality, in-plane variable-density undersampling combined with a sliding-window acquisition and reconstruction approach for increased speed, and an advanced iterative deblurring algorithm.

Rapid -weighted MRI using multishot EPI with retrospective motion and phase correction in the emergency department.

Purpose: Brain MRI is increasingly used in the emergency department (ED), where -weighted MRI is an essential tool for detecting hemorrhage and stroke. The goal of this study was to develop a rapid -weighted MRI technique capable of correcting motion-induced artifacts, thereby simultaneously improving scan time and motion robustness for ED applications.

Methods: A 2D gradient-echo (GRE)-based multishot EPI (msEPI) technique was implemented using a navigator echo for estimating motion-induced errors.

Spiral inflow MRA with sliding-slice localized quadratic encoding.

Purpose: This work proposes a 2D/3D hybrid inflow MRA technique for fast scanning and high SNR and contrast-to-noise (CNR) efficiencies.

Methods: Localized quadratic (LQ) encoding was combined with a sliding-slice spiral acquisition. Inflow MRAs around the circle of Willis and the carotid bifurcations were collected on four healthy volunteers.

Evaluation of axial gradient Echo spiral MRI of the spine at 1.5 T.

Axial gradient echo T2*-weighed MRI of the spine is a valuable diagnostic tool with several advantages over axial T2-weighted TSE MRI, but it suffers from a low signal-to-noise ratio (SNR) and inconsistent image quality. This work investigates the potential of spiral MRI to reduce artifacts and produce improved SNR and image quality in axial T2*-weighted gradient echo MRI of the spine of pediatric patients. For the purposes of image quality evaluation, 15 pediatric patients were recruited among those scheduled for a routine spine or brain exam at 1.

Improving the image quality of 3D FLAIR with a spiral MRI technique.

Purpose: Fluid-attenuated inversion recovery (FLAIR) nulls the CSF signal and is widely used in neuro MRI exams. A 3D scan can provide high SNR, contiguous coverage, and reduced sensitivity to through-plane CSF flow. In this work, a 3D spiral FLAIR technique is proposed to improve the image quality of conventional 3D Cartesian FLAIR.

Correction of B eddy current effects in spiral MRI.

Purpose: B eddy currents are a subtle but important source of artifacts in spiral MRI. This study illustrates the importance of addressing these artifacts and presents a system response-based eddy current correction strategy using B eddy current phase measurements on a phantom.

Methods: B and linear eddy current system response measurements were estimated from phantom-based measurement and used to predict residual eddy current effects in spiral acquisitions.

Prospective motion correction using coil-mounted cameras: Cross-calibration considerations.

Purpose: Optical prospective motion correction substantially reduces sensitivity to motion in neuroimaging of human subjects. However, a major barrier to clinical deployment has been the time-consuming cross-calibration between the camera and MRI scanner reference frames. This work addresses this challenge.

Prospective motion correction using inductively coupled wireless RF coils.

Purpose: A novel prospective motion correction technique for brain MRI is presented that uses miniature wireless radio-frequency coils, or "wireless markers," for position tracking.

Methods: Each marker is free of traditional cable connections to the scanner. Instead, its signal is wirelessly linked to the MR receiver via inductive coupling with the head coil.

Prospective active marker motion correction improves statistical power in BOLD fMRI.

Group level statistical maps of blood oxygenation level dependent (BOLD) signals acquired using functional magnetic resonance imaging (fMRI) have become a basic measurement for much of systems, cognitive and social neuroscience. A challenge in making inferences from these statistical maps is the noise and potential confounds that arise from the head motion that occurs within and between acquisition volumes. This motion results in the scan plane being misaligned during acquisition, ultimately leading to reduced statistical power when maps are constructed at the group level.

Diffusion tensor imaging (DTI) with retrospective motion correction for large-scale pediatric imaging.

Purpose: To develop and implement a clinical DTI technique suitable for the pediatric setting that retrospectively corrects for large motion without the need for rescanning and/or reacquisition strategies, and to deliver high-quality DTI images (both in the presence and absence of large motion) using procedures that reduce image noise and artifacts.

Materials And Methods: We implemented an in-house built generalized autocalibrating partially parallel acquisitions (GRAPPA)-accelerated diffusion tensor (DT) echo-planar imaging (EPI) sequence at 1.5T and 3T on 1600 patients between 1 month and 18 years old.

Combined prospective and retrospective correction to reduce motion-induced image misalignment and geometric distortions in EPI.

Despite rigid-body realignment to compensate for head motion during an echo-planar imaging time-series scan, nonrigid image deformations remain due to changes in the effective shim within the brain as the head moves through the B(0) field. The current work presents a combined prospective/retrospective solution to reduce both rigid and nonrigid components of this motion-related image misalignment. Prospective rigid-body correction, where the scan-plane orientation is dynamically updated to track with the subject's head, is performed using an active marker setup.

Echo-planar imaging with prospective slice-by-slice motion correction using active markers.

Head motion is a fundamental problem in functional magnetic resonance imaging and is often a limiting factor in its clinical implementation. This work presents a rigid-body motion correction strategy for echo-planar imaging sequences that uses micro radiofrequency coil "active markers" for real-time, slice-by-slice prospective correction. Before the acquisition of each echo-planar imaging-slice, a short tracking pulse-sequence measures the positions of three active markers integrated into a headband worn by the subject; the rigid-body transformation that realigns these markers to their initial positions is then fed back to dynamically update the scan-plane, maintaining it at a fixed orientation relative to the head.

Prospective real-time correction for arbitrary head motion using active markers.

Patient motion during an MRI exam can result in major degradation of image quality, and is of increasing concern due to the aging population and its associated diseases. This work presents a general strategy for real-time, intraimage compensation of rigid-body motion that is compatible with multiple imaging sequences. Image quality improvements are established for structural brain MRI acquired during volunteer motion.