An active learning approach to education in MRI technology for the biomedical engineering curriculum

It is challenging to give students an intuitive understanding of the basic magnetic resonance phenomenon and a sample of the many MRI techniques. Whereas compact mathematical descriptions of MRI techniques can be made, students are typically left with no intuitive understanding unless the common sense expressed in the math is in focus. Unfortunately, the nuclear dynamics happen in four dimensions, and are therefore not well suited for illustration on blackboard. 3D movies are more appropriate, but they do not encourage active learning. The typical solution employed by educators is hand waving (literally), since arm motions can to a limited extent be used to illustrate nuclear dynamics. Many students find this confusing, however, and students who do not grasp the meaning during lectures, are left in a bad position. For this reason, educational software was developed over the last decade (the Bloch Simulator). It is freely available and can be run directly from the software homepage that also links to YouTube software presentations aimed at educators and students who have already gotten a first introduction to MRI concepts. The software is mainly aimed at educators for interactive demonstration of MRI techniques but can also be used for student exercises which may significantly improve the understanding of MRI concepts. The presentation demonstrates software made for the first few minutes of MRI education but focuses mostly on the educational value of the more advanced Bloch Simulator. It is explored how, and to what extent, active learning based on the software may improve student understanding. An interactive teaching session on advanced topics (pulse types, the Fourier relationship, selectivity) was evaluated using pre- and post-lecture anonymous questionnaires. These are challenging and significant subjects, and it was hypothesized that the approach may improve student understanding considerably. Though rigorous testing of the benefit over traditional teaching was not within the scope of the project, indications of improved skills were found, and the student satisfaction was excellent

MRI safety in practice: The EU directive on work in electromagnetic fields – practical and clinical aspects

The current paper addresses the practical consequences of the EU directive 2004/40/EC passed in 2004 concerning protection of workers from electromagnetic fields (EMF). These consequences were evaluated in detail only after the directive was passed, and they were found to be severe. Consequently, the directive has not yet been implemented fully in the EU member state's legislation, and a revision is expected before this happens in October 2013, the latest. The revised directive is expected to be based on revised recommendations of the International Commission on Non-Ionizing Radiation Protection (ICNIRP), and may in other ways limit the detrimental consequences for MRI, but this is uncertain. Hence the presented summary of consequences is based mainly on the current directive, representing a realistic worst-case scenario, except for a static field limit that will likely be introduced in a revised directive. An estimated 5-8% of current examinations will be severely affected. The inadvertent effects include reduced access to interventional MRI, and to procedures involving personnel in the scanner rooms during scanning, e.g paediatric examinations, and scanning conducted under anaesthesia. Other consequences are increased use of alternative imaging modalities including X-ray based techniques, hindered development of improved MRI techniques, and general consequences of increased complexity and cost

Oplæg til gymnasie-øvelse i Magnetisk Resonans

Nærværende oplæg giver inspiration til et fysisk/kemisk gymnasie-forløb omhandlende magnetisk resonans (MR), som er et fænomen, der anvendes i medicinsk diagnostik og forskning (MR-skanning) og kemisk analyse (NMR-spektroskopi). Disse fascinerende metoder er baseret på brug af magnetisme, radiobølger, kernefysik og gyro-mekanik, men er grundlæggende ikke mere komplicerede end at de kan forstås intuitivt af elever med klassisk mekanisk intuition og et basalt kendskab til elektromagnetisme

MR-skanning ved 7 tesla feltstyrke etableres i Danmark

Igennem længere tid har en bred kreds af forskere og klinikere på hospitaler og universiteter [1] forsøgt at rejse de nødvendige midler til at etablere ultrahøjfelts MR-skanning i Danmark. I juni 2010 udløstes jubel, da “the John and Birthe Meyer Foundation” meget generøst bevilgede 38,6 Mkr til indkøb af en human MR-skanner med en feltstyrke på 7 tesla. Dette svarer til cirka 140 tusind gange jordens magnetfelt hvilket mere end fordobler hospitalernes hidtil kraftigste felter. Bevillingen supplerede offentlig støtte på 27,4 Mkr fra Forsknings- og Innovationsstyrelsens infrastrukturmidler, og dermed er den nødvendige kapital til etablering af en 7T facilitet ved MR-forskningscentret på Hvidovre Hospital tilvejebragt. Ultimo 2011 kan brugere af MR-skanning i Danmark se frem til væsentligt forbedrede undersøgelser på en række områder, og nye typer målinger, som ikke er mulige ved lavere felt. Med fokus på tekniske forhold beskrives her de unikke muligheder og udfordringer, som skanning ved 7T feltstyrke afstedkommer. Der tages udgangspunkt i en kort generel beskrivelse af MR

Introduction to Magnetic Resonance Imaging Techniques

It is quite possible to acquire images with an MR scanner without understanding the principles behind it, but choosing the best parameters and methods, and interpreting images and artifacts, requires understanding. This text serves as an introduction to magnetic resonance imaging techniques. It is aimed at beginners in possession of only a minimal level of technical expertise, yet it introduces aspects of MR that are typically considered technically challenging. The notes were written in connection with teaching of audiences with mixed backgrounds

The Bloch Simulator and Viewer - Free, interactive MRI visualisation

The Bloch Simulator is 3D graphical software for visualising spin physics and MRI techniques. It provides demonstrations and exploration of otherwise abstract concepts involved in MRI. It is useful for students and teachers alike and is available online at no cost. Phenomena such as precession, resonance, excitation, inhomogeneity and relaxation can be demonstrated. Likewise, rotating frames, weightings, spoilers, spin-echoes, simulated echoes and more can be explored. Finally, MR imaging concepts can be demonstrated, e.g., how the similarity between induced phase roll patterns and the structures of the imaged object is reflected in the MR signal

MRI in Severe Traumatic Brain Injury: Micro- and Macrostructural Changes

The principal aim of the present PhD project was to study quantitatively the long-term microand macrostructural brain changes in survivors from severe traumatic brain injury (TBI). A total of 31 patients admitted for early rehabilitation following severe TBI were included and underwent magnetic resonance imaging (MRI), including Diffusion Tensor Imaging (DTI), at mean 8 weeks post-injury. Follow-up MRI at mean 12 months post-injury was acquired in 25 of the patients. For comparison, healthy matched controls were scanned twice with a similar time interval. Clinical rating during rehabilitation and at 1-year follow-up was performed by experienced staff. Two papers make up the basis of this thesis. Paper I considers the DTI results. This MRI modality was chosen in order to evaluate diffusional changes in brain tissue, potentially useful for characterising the extent of microscopic white matter injury, as well as for tracking microstructural changes during recovery. Using a region-of-interest approach, four white matter regions were studied with additional regions in grey matter and CSF. At the initial scan, patients had abnormal fractional anisotropy (FA) in all white matter regions, which in the cerebral peduncle correlated with 1-year outcome, suggesting that DTI may have prognostic value. At follow-up, FA had partly normalised in some white matter regions, but deviated even more from normal values in other regions. Although these longitudinal findings warrant cautious interpretation, they might indicate microstructural reorganization. Paper II describes a study on the macrostructural brain changes during recovery. Global and regional brain volume changes between the two scan time points were investigated using voxelwise analyses. Despite remarkable clinical improvement in most patients, they all exhibited continued brain volume loss during the scan interval. Global volume change correlated with clinical injury severity, functional status at both scans, and with 1-year outcome. The areas which underwent the most change were structures particularly susceptible to traumatic axonal injury and consequent Wallerian degeneration, indicating that the long-term atrophy is attributable to consequences of axonal injury. Together, these MRI analyses complemented each other in the quantitative assessment of structural brain changes following severe TBI. Applied in the late subacute/early chronic phase of TBI, DTI may capture biological severity at the microstructural level and provide prognostic information. Serial application of the MRI techniques applied in this study enables the monitoring of the extent and distribution of micro- and macrostructural changes during TBI rehabilitation

Introduktion til teknikken bag MR-skanning

Man kan optage billeder med en MR-skanner uden at forstå princippet bag, men det kræver forståelse at opsøge de rette parametre og målemetoder, og at fortolke billeder og artefakter. Teksten her udgør en introduktion til teknikken bag magnetisk resonans (MR) skanning. Dele er møntet på begyndere med et minimum af teknisk baggrund, mens andre dele sigter lidt højere. Dette afspejler, at noterne er skrevet i forbindelse med undervisning af personer med blandet baggrund

Motion correction of Single Voxel Spectroscopy by Independent Component Analysis applied to spectra from non-anesthetized pediatric subjects

For Single Voxel Spectroscopy (SVS), the acquisition of the spectrum is typically repeated n times and then combined with a factor in order to improve the Signal-to-Noise Ratio (SNR). In practice the acquisitions are not only affected by random noise, but also by physiological motion and subject movements. Since the influence of physiological motion such as cardiac and respiratory motion on the data is limited, it can be compensated for without data-loss. Individual acquisitions hampered by subject movements on the other hand need to be rejected, if no correction or compensation is possible. If the individual acquisitions are stored, it is possible to identify and reject the motion-disturbed acquisitions before averaging. Several automatic algorithms were investigated using a dataset of spectra from non-anesthetized infants with a gestational age of 40 weeks. Median filtering removed most subject movement artifacts, but at the cost of increased sensitivity to random noise. Neither Independent Component Analysis (ICA) nor outlier identification with multiple comparisons has this problem. These two algorithms are novel in this context. The peak height values of the metabolites were increased compared to the mean of all acquisitions for both methods, although primarily for the ICA method

NORdic trial of oral Methylprednisolone as add-on therapy to Interferon beta-1a for treatment of relapsing-remitting Multiple Sclerosis (NORMIMS study): a randomised, placebo-controlled trial

Treatment of relapsing-remitting multiple sclerosis with interferon beta is only partly effective, and new more effective and safe strategies are needed. Our aim was to assess the efficacy of oral methylprednisolone as an add-on therapy to subcutaneous interferon beta-1a to reduce the yearly relapse rate in patients with relapsing-remitting multiple sclerosis. Methods: NORMIMS (NORdic trial of oral Methylprednisolone as add-on therapy to Interferon beta-1a for treatment of relapsing-remitting Multiple Sclerosis) was a randomised, placebo-controlled trial done in 29 neurology departments in Denmark, Norway, Sweden, and Finland. We enrolled outpatients with relapsing-remitting multiple sclerosis who had had at least one relapse within the previous 12 months despite subcutaneous interferon beta-1a treatment (44 microg three times per week). We randomly allocated patients by computer to add-on therapy of either 200 mg methylprednisolone or matching placebo, both given orally on 5 consecutive days every 4 weeks for at least 96 weeks. The primary outcome measure was mean yearly relapse rate. Primary analyses were by intention to treat. This trial is registered, number ISRCTN16202527. Findings: 66 patients were assigned to interferon beta and oral methylprednisolone and 64 were assigned to interferon beta and placebo. A high proportion of patients withdrew from the study before week 96 (26% [17 of 66] on methylprednisolone vs 17% [11 of 64] on placebo). The mean yearly relapse rate was 0.22 for methylprednisolone compared with 0.59 for placebo (62% reduction, 95% CI 39-77%; p<0.0001). Sleep disturbance and neurological and psychiatric symptoms were the most frequent adverse events recorded in the methylprednisolone group. Bone mineral density had not changed after 96 weeks. Interpretation: Oral methylprednisolone given in pulses every 4 weeks as an add-on therapy to subcutaneous interferon beta-1a in patients with relapsing-remitting multiple sclerosis leads to a significant reduction in relapse rate. However, because of the small number of patients and the high dropout rate, these findings need to be corroborated in larger cohorts