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Objectives: In patients with stable ischemic heart disease, there is no evidence for the effect of revascularization treatment timing on the need for repeat procedures. We aimed to determine if repeat revascularizations differed among patients who received coronary artery bypass graft surgery after the time recommended by physicians compared with those who had timely percutaneous coronary intervention. Methods: We identified 25,520 British Columbia residents 60 years or older who underwent first-time nonemergency revascularization for angiographically proven, stable left main or multivessel ischemic heart disease between January 1, 2001, and December 31, 2016. We estimated unadjusted and adjusted cumulative incidence functions for repeat revascularization, in the presence of death as a competing risk, after index revascularization or last staged percutaneous coronary intervention for patients undergoing delayed coronary artery bypass grafting compared with timely percutaneous coronary intervention. Results: After adjustment with inverse probability of treatment weights, at 3 years, patients who underwent delayed coronary artery bypass grafting had a statistically significant lower cumulative incidence of a repeat revascularization compared with patients who received timely percutaneous coronary intervention (4.84% delayed coronary artery bypass grafting, 12.32% timely percutaneous coronary intervention; subdistribution hazard ratio, 0.16, 95% CI, 0.04-0.65). Conclusions: Patients who undergo delayed coronary artery bypass grafting have a lower cumulative incidence of repeat revascularization than patients who undergo timely percutaneous coronary intervention. Patients who want to wait to receive coronary artery bypass grafting will see the benefit of lower repeat revascularization over percutaneous coronary intervention unaffected by a delay in treatment.
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PURPOSE: QSM provides insight into healthy brain aging and neuropathologies such as multiple sclerosis (MS), traumatic brain injuries, brain tumors, and neurodegenerative diseases. Phase data for QSM are usually acquired from 3D gradient-echo (3D GRE) scans with long acquisition times that are detrimental to patient comfort and susceptible to patient motion. This is particularly true for scans requiring whole-brain coverage and submillimeter resolutions. In this work, we use a multishot 3D echo plannar imaging (3D EPI) sequence with shot-selective 2D CAIPIRIHANA to acquire high-resolution, whole-brain data for QSM with minimal distortion and blurring. METHODS: To test clinical viability, the 3D EPI sequence was used to image a cohort of MS patients at 1-mm isotropic resolution at 3 T. Additionally, 3D EPI data of healthy subjects were acquired at 1-mm, 0.78-mm, and 0.65-mm isotropic resolution with varying echo train lengths (ETLs) and compared with a reference 3D GRE acquisition. RESULTS: The appearance of the susceptibility maps and the susceptibility values for segmented regions of interest were comparable between 3D EPI and 3D GRE acquisitions for both healthy and MS participants. Additionally, all lesions visible in the MS patients on the 3D GRE susceptibility maps were also visible on the 3D EPI susceptibility maps. The interplay among acquisition time, resolution, echo train length, and the effect of distortion on the calculated susceptibility maps was investigated. CONCLUSION: We demonstrate that the 3D EPI sequence is capable of rapidly acquiring submillimeter resolutions and providing high-quality, clinically relevant susceptibility maps.
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Encéfalo , Imagen Eco-Planar , Imagenología Tridimensional , Esclerosis Múltiple , Humanos , Imagenología Tridimensional/métodos , Esclerosis Múltiple/diagnóstico por imagen , Encéfalo/diagnóstico por imagen , Imagen Eco-Planar/métodos , Adulto , Masculino , Femenino , Algoritmos , Persona de Mediana Edad , Mapeo Encefálico/métodos , Procesamiento de Imagen Asistido por Computador/métodos , Interpretación de Imagen Asistida por Computador/métodosRESUMEN
Isolated REM sleep behavior disorder (iRBD) is an early stage of synucleinopathy with most patients progressing to Parkinson's disease (PD) or related conditions. Quantitative susceptibility mapping (QSM) in PD has identified pathological iron accumulation in the substantia nigra (SN) and variably also in basal ganglia and cortex. Analyzing whole-brain QSM across iRBD, PD, and healthy controls (HC) may help to ascertain the extent of neurodegeneration in prodromal synucleinopathy. 70 de novo PD patients, 70 iRBD patients, and 60 HCs underwent 3 T MRI. T1 and susceptibility-weighted images were acquired and processed to space standardized QSM. Voxel-based analyses of grey matter magnetic susceptibility differences comparing all groups were performed on the whole brain and upper brainstem levels with the statistical threshold set at family-wise error-corrected p-values <.05. Whole-brain analysis showed increased susceptibility in the bilateral fronto-parietal cortex of iRBD patients compared to both PD and HC. This was not associated with cortical thinning according to the cortical thickness analysis. Compared to iRBD, PD patients had increased susceptibility in the left amygdala and hippocampal region. Upper brainstem analysis revealed increased susceptibility within the bilateral SN for both PD and iRBD compared to HC; changes were located predominantly in nigrosome 1 in the former and nigrosome 2 in the latter group. In the iRBD group, abnormal dopamine transporter SPECT was associated with increased susceptibility in nigrosome 1. iRBD patients display greater fronto-parietal cortex involvement than incidental early-stage PD cohort indicating more widespread subclinical neuropathology. Dopaminergic degeneration in the substantia nigra is paralleled by susceptibility increase, mainly in nigrosome 1.
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Enfermedad de Parkinson , Trastorno de la Conducta del Sueño REM , Sinucleinopatías , Humanos , Trastorno de la Conducta del Sueño REM/diagnóstico por imagen , Sinucleinopatías/complicaciones , Sinucleinopatías/patología , Encéfalo/diagnóstico por imagen , Encéfalo/patología , Sustancia Negra/diagnóstico por imagen , Sustancia Negra/patología , Enfermedad de Parkinson/complicaciones , HierroRESUMEN
Intraductal T2 mapping based on a catheter receiver is proposed as a method of visualizing the extent of intraductal and periductal cholangiocarcinoma (CCA). Compared to external receivers, internal receivers provide locally enhanced signal-to-noise ratios by virtue of their lower field-of-view for body noise, allowing smaller voxels and higher resolution. However, inherent radial sensitivity variation and segmentation for patient safety both distort image brightness. We discuss simulated T2 weighted images and T2 maps, and in vitro images obtained using a thin film catheter receiver of a freshly resected liver specimen containing a polypoid intraductal tumor from a patient with CCA. T2 mapping provides a simple method of compensating non-uniform signal reception patterns of catheter receivers, allowing the visualization of tumor extent without contrast enhancement and potentially quantitative tissue characterization. Potential advantages and disadvantages of in vivo intraductal imaging are considered.
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Four years after the first case of COVID-19, the world is still determining how best to prevent and control the long-term effects of SARS-CoV-2 infection. Non-pharmaceutical interventions (NPIs) were employed at the start of the pandemic as the only available options, prior to effective vaccines and antiviral agents. The World Health Organization recommended dual vaccination for 70% worldwide as the threshold for a return to "normal" community life. Immunization rates needed to increase in all global regions, irrespective of socioeconomic status, necessitating more equitable access. During the pandemic, wealthier countries hoarded vaccine supplies even when their citizens were immunized. This highlights the already enormous difficulties in healthcare provision faced by low-income sub-Saharan African countries, which remain at risk as industrialized nations have progressed to a post-pandemic era. Thus, in addition to redoubling vaccination efforts public health policymakers should consider ongoing and future use of NPIs. In this narrative account, we advocate that various NPI practices should not be shelved; rather, more research is needed to evaluate their impact in parallel with booster vaccination. This especially applies to so-called "long COVID". Lessons learned from implementing best practices in resource-limited settings should be incorporated into preparedness guidelines for future infectious disease outbreaks.
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Introduction: Chronic rhinosinusitis causes severe symptoms that can affect patient quality of life. Endoscopic sinus surgery can be effective in improving symptoms, although surgical outcomes can be compromised post-operatively, and revision surgery is required in a proportion of patients. This study compares outcomes and healthcare resource use in patients undergoing sinus surgery with or without Chitogel as a post-operative dressing. Methods: A retrospective cohort study was conducted using deidentified audit data from adult patients with severe chronic rhinosinusitis, who underwent endoscopic sinus surgery between January 2016 and December 2021. Patients in the intervention group received Chitogel as a post-operative dressing, and control patients received standard best-practice care. Cox Proportional Hazards survival analysis was used to compare revision surgery rates and time to revision between treatment groups. The rate of revision surgery was used to estimate potential health sector savings associated with use of Chitogel following surgery compared to the control arm, considering initial treatment costs and the cost of revision surgery. Results: Over 18-24 months, patients treated with Chitogel demonstrated significantly lower rates of revision surgery (p = 0.035), and a trend towards decreased use of post-operative steroids, compared to control. Potential health sector savings due to reduced rates of revision surgery following use of Chitogel are estimated as NZ $753,000 per 100 patients. Conclusion: Severe chronic rhinosinusitis patients treated with Chitogel had lower rates of revision surgery within the first 18-24 months post-operative. These findings suggest that use of Chitogel can improve long-term patient outcomes and should improve health system efficiency.
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The commonly heard aphorism about history repeating itself suggests an endless cycle of recurring events. However, George Santayana offered a similar sentiment when he said, "Those who do not learn from history are doomed to repeat it". This emphasises that the responsibility for the recurrence of events lies not with history itself, but with humanity. It underscores that if we desire change, it is our responsibility to initiate it, rather than attributing it to external forces such as fate, luck, or time. With this thought in mind, here we offer a narrative view from sub-Saharan Africa, focusing primarily on our own experiences in Nigeria and Uganda, on what harsh lessons can be learnt from the COVID-19 pandemic regarding emergency preparedness to respond effectively to the next major infectious disease outbreak. Four strategies are suggested, the implementation of which may contribute substantially to safeguarding against an experience similar to the catastrophic public health, social and economic costs borne by African nations during COVID-19 and in its immediate aftermath.
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Introduction: Magnetic resonance elastography (MRE) is a non-invasive method to quantify biomechanical properties of human tissues. It has potential in diagnosis and monitoring of kidney disease, if established in clinical practice. The interplay of flow and volume changes in renal vessels, tubule, urinary collection system and interstitium is complex, but physiological ranges of in vivo viscoelastic properties during fasting and hydration have never been investigated in all gross anatomical segments simultaneously. Method: Ten healthy volunteers underwent two imaging sessions, one following a 12-hour fasting period and the second after a drinking challenge of >10 mL per kg body weight (60-75 min before the second examination). High-resolution renal MRE was performed using a novel driver with rotating eccentric mass placed at the posterior-lateral wall to couple waves (50 Hz) to the kidney. The biomechanical parameters, shear wave speed (cs in m/s), storage modulus (Gd in kPa), loss modulus (Gl in kPa), phase angle (Υ=2πatanGlGd) and attenuation (α in 1/mm) were derived. Accurate separation of gross anatomical segments was applied in post-processing (whole kidney, cortex, medulla, sinus, vessel). Results: High-quality shear waves coupled into all gross anatomical segments of the kidney (mean shear wave displacement: 163 ± 47 µm, mean contamination of second upper harmonics <23%, curl/divergence: 4.3 ± 0.8). Regardless of the hydration state, median Gd of the cortex and medulla (0.68 ± 0.11 kPa) was significantly higher than that of the sinus and vessels (0.48 ± 0.06 kPa), and consistently, significant differences were found in cs, Υ, and Gl (all p < 0.001). The viscoelastic parameters of cortex and medulla were not significantly different. After hydration sinus exhibited a small but significant reduction in median Gd by -0.02 ± 0.04 kPa (p = 0.01), and, consequently, the cortico-sinusoidal-difference in Gd increased by 0.04 ± 0.07 kPa (p = 0.05). Only upon hydration, the attenuation in vessels became lower (0.084 ± 0.013 1/mm) and differed significantly from the whole kidney (0.095 ± 0.007 1/mm, p = 0.01). Conclusion: High-resolution renal MRE with an innovative driver and well-defined 3D segmentation can resolve all renal segments, especially when including the sinus in the analysis. Even after a prolonged hydration period the approach is sensitive to small hydration-related changes in the sinus and in the cortico-sinusoidal-difference.
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BACKGROUND: Podcasts have proven to be a successful alternative source of educational material for students. Given the ability to listen to podcasts 24/7 and while on the go, this technology has the potential to provide informative and educational material to a large number of people at any given time. Podcasts are usually freely available on commonly used mobile devices, such as smartphones, laptops, and tablets. OBJECTIVE: This paper describes the impact of health-related podcasts as an intervention tool to support the knowledge and awareness of nursing students on a given topic. METHODS: Pre- and postpodcast questionnaires will gather data regarding the participants' knowledge and awareness of two topics-gestational diabetes and mental health. This intervention will be tested on general nursing undergraduate students. The total number of students (N=2395) from the participating universities are broken down as follows: (1) University College Cork (n=850) and the University of Galway (n=450) in Ireland, (2) Mzuzu University in Malawi (n=719), and (3) University of Fort Hare in South Africa (n=376). RESULTS: The study received ethical approval from the University College Cork Ethics Committee (2022-027A1). The approval obtained from University College Cork sufficed as ethics coverage for the University of Galway in Ireland. Ethics approval was also received from the Mzuzu University Research Ethics Committee (ID MZUNIREC/DOR/23/28) and the Inter-Faculty Research Ethics Committee of the University of Fort Hare (ID CIL002-21). Data collection is currently underway and will continue until the end of February 2024. The quantitative and qualitative data are expected to be analyzed in March 2024. CONCLUSIONS: Results from this study will allow for an investigation into the impact of podcasts in different settings: a high-income country (Ireland), an upper-middle-income country (South Africa), and a low-to-middle-income country (Malawi). The data gathered from this feasibility study will provide more clarity on the potential utility of podcasts as an intervention tool. We will gather data regarding listener demographics (eg, country of residence, age, gender, and year of study). INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/50735.
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This article provides recommendations for implementing QSM for clinical brain research. It is a consensus of the International Society of Magnetic Resonance in Medicine, Electro-Magnetic Tissue Properties Study Group. While QSM technical development continues to advance rapidly, the current QSM methods have been demonstrated to be repeatable and reproducible for generating quantitative tissue magnetic susceptibility maps in the brain. However, the many QSM approaches available have generated a need in the neuroimaging community for guidelines on implementation. This article outlines considerations and implementation recommendations for QSM data acquisition, processing, analysis, and publication. We recommend that data be acquired using a monopolar 3D multi-echo gradient echo (GRE) sequence and that phase images be saved and exported in Digital Imaging and Communications in Medicine (DICOM) format and unwrapped using an exact unwrapping approach. Multi-echo images should be combined before background field removal, and a brain mask created using a brain extraction tool with the incorporation of phase-quality-based masking. Background fields within the brain mask should be removed using a technique based on SHARP or PDF, and the optimization approach to dipole inversion should be employed with a sparsity-based regularization. Susceptibility values should be measured relative to a specified reference, including the common reference region of the whole brain as a region of interest in the analysis. The minimum acquisition and processing details required when reporting QSM results are also provided. These recommendations should facilitate clinical QSM research and promote harmonized data acquisition, analysis, and reporting.
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Encéfalo , Procesamiento de Imagen Asistido por Computador , Consenso , Procesamiento de Imagen Asistido por Computador/métodos , Encéfalo/diagnóstico por imagen , Encéfalo/metabolismo , Cabeza , Imagen por Resonancia Magnética/métodos , Algoritmos , Mapeo Encefálico/métodosRESUMEN
PURPOSE: Subject movement during the MR examination is inevitable and causes not only image artifacts but also deteriorates the homogeneity of the main magnetic field (B0 ), which is a prerequisite for high quality data. Thus, characterization of changes to B0 , for example induced by patient movement, is important for MR applications that are prone to B0 inhomogeneities. METHODS: We propose a deep learning based method to predict such changes within the brain from the change of the head position to facilitate retrospective or even real-time correction. A 3D U-net was trained on in vivo gradient-echo brain 7T MRI data. The input consisted of B0 maps and anatomical images at an initial position, and anatomical images at a different head position (obtained by applying a rigid-body transformation on the initial anatomical image). The output consisted of B0 maps at the new head positions. We further fine-trained the network weights to each subject by measuring a limited number of head positions of the given subject, and trained the U-net with these data. RESULTS: Our approach was compared to established dynamic B0 field mapping via interleaved navigators, which suffer from limited spatial resolution and the need for undesirable sequence modifications. Qualitative and quantitative comparison showed similar performance between an interleaved navigator-equivalent method and proposed method. CONCLUSION: It is feasible to predict B0 maps from rigid subject movement and, when combined with external tracking hardware, this information could be used to improve the quality of MR acquisitions without the use of navigators.
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Encéfalo , Imagen por Resonancia Magnética , Humanos , Estudios Retrospectivos , Imagen por Resonancia Magnética/métodos , Encéfalo/diagnóstico por imagen , Movimiento (Física) , Movimiento , Procesamiento de Imagen Asistido por Computador/métodos , ArtefactosRESUMEN
BACKGROUND: Most ultrasound-based methods for assessing liver fibrosis still need further validation with liver biopsy used as gold standard to assess their accuracy. AIMS: To assess accuracy of three shear wave elastography (SWE) methods: 1) Philips Elast Point Quantification (ElastPQTM), 2) Siemens Virtual TouchTM Quantification (VTQ) acoustic radiation force impulse (ARFI), and 3) transient elastography (TE) measured by Echosens FibroscanTM. METHODS: 160 patients underwent liver stiffness measurements (LSM) with three SWE methods immediately prior to liver biopsy. RESULTS: The number of LSM required for reliable studies could be reduced to 6 for ElastPQ and to 7 for VTQ from standard recommendations of 10. Significant fibrosis and interquartile range/median (IQR/M)> 30 were independent predictors for lower reliability for detection of liver fibrosis. Ordinal logistic regression corrected for age showed that there was a significant interaction between steatosis (p = 0.008) and lobular inflammation (p = 0.04) and VTQ (ARFI) and between lobular inflammation and TE (p = 0.006). CONCLUSIONS: We showed variations in SWE measurements using different ARFI technologies. TE and ElastPQ achieved good diagnostic performance, whereas VTQ showed lower diagnostic accuracy. The number of measurements required for reliable studies can be reduced to 6 for ElastPQ and to 7 for VTQ, which have important clinical implications.
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Diagnóstico por Imagen de Elasticidad , Hepatopatías , Humanos , Diagnóstico por Imagen de Elasticidad/métodos , Reproducibilidad de los Resultados , Hepatopatías/diagnóstico , Hígado/diagnóstico por imagen , Hígado/patología , Cirrosis Hepática/diagnóstico por imagen , Cirrosis Hepática/patología , Biopsia , Inflamación/patologíaRESUMEN
Although the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) primarily attacks the respiratory system, other organs, such as the liver, are also affected. In this overview, the effects of SARS-CoV-2 infection on the liver in both healthy people and in those with pre-existing liver disease are documented; the relationship between coronavirus disease 19 (COVID-19) vaccination and liver injury is examined; the mechanism of SARS-CoV-2-associated liver injury is explored; and the long-term consequences of COVID-19 are delineated, both in people with and without pre-existing liver disease.
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BACKGROUND: Screening for opisthorchiasis, a parasitic worm infection affecting many millions of people in Southeast Asia, has traditionally relied on faecal egg examination such as the formalin-ethyl acetate concentration technique (FECT) and Kato-Katz method. Although the urinary enzyme-linked immunosorbent assay (ELISA) has been used more recently, we developed a urinary antigen-based rapid diagnostic test (RDT) to simplify diagnosis and as a point-of-care testing (POCT) and field applications for surveillance and control of opisthorchiasis. METHODS: A urinary Opisthorchis viverrini (OV)-RDT was developed using immunochromatographic methodology with a specific monoclonal antibody against OV. The diagnostic performance of the urinary OV-RDT was compared to that of quantitative faecal FECT and urinary antigen ELISA (n = 493). Cross-reactivities of urinary OV-RDT with other helminthiases coexisted with O. viverrini were determined (n = 96). A field trial in the application of urinary OV-RDT was compared with urinary antigen ELISA at baseline screening and assessment of drug treatment outcomes in opisthorchiasis (n = 1629). The McNemar chi-square, Kruskal-Wallis and Cohen's kappa coefficient (κ-value) tests were used for statistical analyses. RESULTS: Urinary OV-RDT had sensitivity of 94.2% and specificity of 93.2%, compared to faecal FECT. Urinary OV-RDT had high diagnostic agreement (Kappa = 0.842-0.874, P < 0.001) and quantitative correlation with urinary antigen ELISA (Kruskal-Wallis tests = 316.2, P < 0.0001) and faecal FECT (Kruskal-Wallis tests = 362.3, P < 0.0001). The positive rates by OV-RDT, ELISA and FECT were 48.9%, 52.5% and 49.3%, respectively. Cross-reactions of urinary OV-RDT with other helminthiases were few (2%). Field trials of urinary OV-RDT yielded comparable prevalence of O. viverrini between urinary OV-RDT (53.2%) and urinary antigen ELISA (54.0%). OV screening showed high diagnostic agreement (kappa > 0.8, P < 0.0001) between urinary OV-RDT and urinary antigen ELISA. The cure rates of opisthorchiasis at 1 month post-praziquantel treatment determined by urinary OV-RDT (86.6%) and urinary antigen ELISA (80.5%) were similar (P > 0.05). CONCLUSIONS: The urinary OV-RDT test has high potential as a new tool for screening and evaluating treatment outcomes in opisthorchiasis. The ease of sample collection and simplicity of urinary OV-RDT may facilitate mass screening, control and elimination of opisthorchiasis, thereby contributing to a reduction in the disease burden in Southeast Asia.
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Opistorquiasis , Opisthorchis , Animales , Humanos , Opistorquiasis/diagnóstico , Opistorquiasis/tratamiento farmacológico , Opistorquiasis/epidemiología , Prueba de Diagnóstico Rápido , Sensibilidad y Especificidad , Praziquantel/uso terapéutico , Tailandia/epidemiologíaRESUMEN
Hepatocellular carcinoma (HCC) is the main liver malignancy and has a high mortality rate. The discovery of novel biomarkers for early diagnosis, prognosis, and stratification purposes has the potential to alleviate its disease burden. Mass spectrometry (MS) is one of the principal technologies used in metabolomics, with different experimental methods and machine types for different phases of the biomarker discovery process. Here, we review why MS applications are useful for liver cancer, explain the MS technique, and briefly summarise recent findings from metabolomic MS studies on HCC. We also discuss the current challenges and the direction for future research.
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Quantitative Susceptibility Mapping has the potential to provide additional insights into neurological diseases but is typically based on a quite long (5-10 min) 3D gradient-echo scan which is highly sensitive to motion. We propose an ultra-fast acquisition based on three orthogonal (sagittal, coronal and axial) 2D simultaneous multi-slice EPI scans with 1 mm in-plane resolution and 3 mm thick slices. Images in each orientation are corrected for susceptibility-related distortions and co-registered with an iterative non-linear Minimum Deformation Averaging (Volgenmodel) approach to generate a high SNR, super-resolution data set with an isotropic resolution of close to 1 mm. The net acquisition time is 3 times the volume acquisition time of EPI or about 12 s, but the three volumes could also replace "dummy scans" in fMRI, making it feasible to acquire QSM in little or No Additional Time for Imaging (NATIve). NATIve QSM values agreed well with reference 3D GRE QSM in the basal ganglia in healthy subjects. In patients with multiple sclerosis, there was also a good agreement between the susceptibility values within lesions and control ROIs and all lesions which could be seen on 3D GRE QSMs could also be visualized on NATIve QSMs. The approach is faster than conventional 3D GRE by a factor of 25-50 and faster than 3D EPI by a factor of 3-5. As a 2D technique, NATIve QSM was shown to be much more robust to motion than the 3D GRE and 3D EPI, opening up the possibility of studying neurological diseases involving iron accumulation and demyelination in patients who find it difficult to lie still for long enough to acquire QSM data with conventional methods.
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Imagen Eco-Planar , Humanos , Imagen Eco-Planar/métodos , Ganglios Basales/diagnóstico por imagenRESUMEN
BACKGROUND: Currently, two major magnetic resonance (MR) vendors provide commercial 7T scanners that are approved by the Food and Drug Administration (FDA) for clinical application. There is growing interest in ultrahigh-field MRI because of the improved clinical results in terms of morphological detail, as well as functional and metabolic imaging capabilities. MATERIALS AND METHODS: The 7T systems benefit from a higher signal-to-noise ratio, which scales supralinearly with field strength, a supralinear increase in the blood oxygenation level dependent (BOLD) contrast for functional MRI and susceptibility weighted imaging (SWI), and the chemical shift increases linearly with field strength with consequently higher spectral resolution. RESULTS: In multiple sclerosis (MS), 7T imaging enables visualization of cortical lesions, the central vein sign, and paramagnetic rim lesions, which may be beneficial for the differential diagnosis between MS and other neuroinflammatory diseases in challenging and inconclusive clinical presentations and are seen as promising biomarkers for prognosis and treatment monitoring. The recent development of high-resolution proton MR spectroscopic imaging in clinically reasonable scan times has provided new insights into tumor metabolism and tumor grading as well as into early metabolic changes that may precede inflammatory processes in MS. This technique also improves the detection of epileptogenic foci in the brain. Multi-nuclear clinical applications, such as sodium imaging, have shown great potential for the evaluation of repair tissue quality after cartilage transplantation and in the monitoring of newly developed cartilage regenerative drugs for osteoarthritis. CONCLUSION: For special clinical applications, such as SWI in MS, MR spectroscopic imaging in tumors, MS and epilepsy, and sodium imaging in cartilage repair, 7T may become a new standard.
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The boundaries between tissues with different magnetic susceptibilities generate inhomogeneities in the main magnetic field which change over time due to motion, respiration and system instabilities. The dynamically changing field can be measured from the phase of the fMRI data and corrected. However, methods for doing so need multi-echo data, time-consuming reference scans and/or involve error-prone processing steps, such as phase unwrapping, which are difficult to implement robustly on the MRI host. The improved dynamic distortion correction method we propose is based on the phase of the single-echo EPI data acquired for fMRI, phase offsets calculated from a triple-echo, bipolar reference scan of circa 3-10 s duration using a method which avoids the need for phase unwrapping and an additional correction derived from one EPI volume in which the readout direction is reversed. This Reverse-Encoded First Image and Low resoLution reference scan (REFILL) approach is shown to accurately measure B0 as it changes due to shim, motion and respiration, even with large dynamic changes to the field at 7 T, where it led to a > 20% increase in time-series signal to noise ratio compared to data corrected with the classic static approach. fMRI results from REFILL-corrected data were free of stimulus-correlated distortion artefacts seen when data were corrected with static field mapping. The method is insensitive to shim changes and eddy current differences between the reference scan and the fMRI time series, and employs calculation steps that are simple and robust, allowing most data processing to be performed in real time on the scanner image reconstruction computer. These improvements make it feasible to routinely perform dynamic distortion correction in fMRI.