Evaluating amplified magnetic resonance imaging as an input for computational fluid dynamics models of the cerebrospinal fluid.

Computational models that accurately capture cerebrospinal fluid (CSF) dynamics are valuable tools to study neurological disorders and optimize clinical treatments. While CSF dynamics interrelate with deformations of the ventricular volumes, these deformations have been simplified and even discarded in computational models because of the lack of detailed measurements. Amplified magnetic resonance imaging (aMRI) enables visualization of these complex deformations, but this technique has not been used for predicting CSF dynamics.

Dynamic visualization of brain pulsations using amplified MRI: methodology and applications.

Brain pulsatility offers a compelling application in the study of cerebral biomechanics, particularly for mild traumatic brain injury (mTBI) and elevated intracranial pressure (ICP). In this study, we used amplified MRI to quantify brain tissue pulsations. Dynamic mode decomposition (DMD) processing was then applied to provide a spatio-temporal analysis of motion.

Exercise modulates brain pulsatility: insights from q-aMRI and MRI-based flow methods.

This study investigates intracranial dynamics following the Monro-Kellie doctrine, depicting how brain pulsatility, cerebrospinal fluid (CSF) flow and cerebral blood flow (CBF) interact under resting and exercise conditions. Using quantitative amplified magnetic resonance imaging (q-aMRI) alongside traditional MRI flow metrics, we measured and analysed blood flow, CSF dynamics and brain displacement in a cohort of healthy adults both at rest and during low-intensity handgrip exercise. Exercise was found to reduce pulsatility in CBF while increasing CSF flow and eliminating CSF regurgitation, highlighting a shift towards more sustained forward flow patterns (from cranial to spinal compartments).

Ultra-High Contrast (UHC) MRI of the Brain, Spinal Cord and Optic Nerves in Multiple Sclerosis Using Directly Acquired and Synthetic Bipolar Filter (BLAIR) Images.

In this educational review, the basic physics underlying the use of ultra-high contrast (UHC) bipolar filter (BLAIR) sequences, including divided subtracted inversion recovery (dSIR), is explained. These sequences can increase the contrast produced by small changes in T by a factor of ten or more compared with conventional IR sequences. In illustrative cases, the sequences were used in multiple sclerosis (MS) patients during relapse and remission and were compared with positionally matched conventional (T-weighted spin echo, T-FLAIR) images.

Log subtracted inversion recovery.

Magnetic resonance imaging (MRI) techniques have recently been developed for obtaining high T contrast images using inversion recovery (IR) images at two inversion times (TIs) rather than a single TI. They use simple mathematical operations - multiplication, addition, subtraction, division - to create images not attainable by conventional IR. The present study describes a novel two-point IR technique formed by the subtraction of log images.

Characterizing the Effect of Repetitive Head Impact Exposure and mTBI on Adolescent Collision Sports Players' Brain with Diffusion Magnetic Resonance Imaging.

Athletes in collision sports frequently sustain repetitive head impacts (RHI), which, while not individually severe enough for a clinical mild traumatic brain injury (mTBI) diagnosis, can compromise neuronal organization by transferring mechanical energy to the brain. Although numerous studies target athletes with mTBI, there is a lack of longitudinal research on young collision sport participants, highlighting an unaddressed concern regarding cumulative RHI effects on brain microstructures. Therefore, this study aimed to investigate the microstructural changes in the brains' of high school rugby players due to repeated head impacts and to establish a correlation between clinical symptoms, cumulative effects of RHI exposure, and changes in the brain's microstructure.

Validation of an ultrahigh contrast divided subtracted inversion recovery technique using a standard T phantom.

The divided subtracted inversion recovery (dSIR) is a high T contrast technique that shows changes in white matter in patients with traumatic brain injury and hypoxic injury. The changes can be explained by small differences in T; however, to date, there has been no independent validation of the technique using a standard reference. The present study develops the theory of the dSIR signal and performs validation using the NIST/ISMRM T phantom.

3D Quantitative-Amplified Magnetic Resonance Imaging (3D q-aMRI).

Amplified MRI (aMRI) is a promising new technique that can visualize pulsatile brain tissue motion by amplifying sub-voxel motion in cine MRI data, but it lacks the ability to quantify the sub-voxel motion field in physical units. Here, we introduce a novel post-processing algorithm called 3D quantitative amplified MRI (3D q-aMRI). This algorithm enables the visualization and quantification of pulsatile brain motion.

A computational fluid dynamics study to assess the impact of coughing on cerebrospinal fluid dynamics in Chiari type 1 malformation.

Chiari type 1 malformation is a neurological disorder characterized by an obstruction of the cerebrospinal fluid (CSF) circulation between the brain (intracranial) and spinal cord (spinal) compartments. Actions such as coughing might evoke spinal cord complications in patients with Chiari type 1 malformation, but the underlying mechanisms are not well understood. More insight into the impact of the obstruction on local and overall CSF dynamics can help reveal these mechanisms.

Ultra-High Contrast MRI: Using Divided Subtracted Inversion Recovery (dSIR) and Divided Echo Subtraction (dES) Sequences to Study the Brain and Musculoskeletal System.

Divided and subtracted MRI is a novel imaging processing technique, where the difference of two images is divided by their sum. When the sequence parameters are chosen properly, this results in images with a high T or T weighting over a small range of tissues with specific T and T values. In the T domain, we describe the implementation of the divided Subtracted Inversion Recovery Sequence (dSIR), which is used to image very small changes in T from normal in white matter.

Diagnosis of Delayed Post-Hypoxic Leukoencephalopathy (Grinker's Myelinopathy) with MRI Using Divided Subtracted Inversion Recovery (dSIR) Sequences: Time for Reappraisal of the Syndrome?

Delayed Post-Hypoxic Leukoencephalopathy (DPHL), or Grinker's myelinopathy, is a syndrome in which extensive changes are seen in the white matter of the cerebral hemispheres with MRI weeks or months after a hypoxic episode. T-weighted spin echo (T-wSE) and/or T-Fluid Attenuated Inversion Recovery (T-FLAIR) images classically show diffuse hyperintensities in white matter which are thought to be near pathognomonic of the condition. The clinical features include Parkinsonism and akinetic mutism.

Targeted magnetic resonance imaging (tMRI) of small changes in the T and spatial properties of normal or near normal appearing white and gray matter in disease of the brain using divided subtracted inversion recovery (dSIR) and divided reverse subtracted inversion recovery (drSIR) sequences.

This review describes targeted magnetic resonance imaging (tMRI) of small changes in the T and the spatial properties of normal or near normal appearing white or gray matter in disease of the brain. It employs divided subtracted inversion recovery (dSIR) and divided reverse subtracted inversion recovery (drSIR) sequences to increase the contrast produced by small changes in T by up to 15 times compared to conventional T-weighted inversion recovery (IR) sequences such as magnetization prepared-rapid acquisition gradient echo (MP-RAGE). This increase in contrast can be used to reveal disease with only small changes in T in normal appearing white or gray matter that is not apparent on conventional MP-RAGE, T-weighted spin echo (T-wSE) and/or fluid attenuated inversion recovery (T-FLAIR) images.

Roadmap for an imaging and modelling paediatric study in rural NZ.

Our study methodology is motivated from three disparate needs: one, imaging studies have existed in silo and study organs but not across organ systems; two, there are gaps in our understanding of paediatric structure and function; three, lack of representative data in New Zealand. Our research aims to address these issues in part, through the combination of magnetic resonance imaging, advanced image processing algorithms and computational modelling. Our study demonstrated the need to take an organ-system approach and scan multiple organs on the same child.