Number Of Magnetic Resonance Imaging Research Articles

Deep Learning Accelerated Image Reconstruction of Fluid-Attenuated Inversion Recovery Sequence in Brain Imaging: Reduction of Acquisition Time and Improvement of Image Quality

Fluid-attenuated inversion recovery (FLAIR) imaging is playing an increasingly significant role in the detection of brain metastases with a concomitant increase in the number of magnetic resonance imaging (MRI) examinations. Therefore, the purpose of this study was to investigate the impact on image quality and diagnostic confidence of an innovative deep learning-based accelerated FLAIR (FLAIRDLR) sequence of the brain compared to conventional (standard) FLAIR (FLAIRS) imaging. Seventy consecutive patients with staging cerebral MRIs were retrospectively enrolled in this single-center study. The FLAIRDLR was conducted using the same MRI acquisition parameters as the FLAIRS sequence, except for a higher acceleration factor for parallel imaging (from 2 to 4), which resulted in a shorter acquisition time of 1:39minute instead of 2:40minutes (-38%). Two specialized neuroradiologists evaluated the imaging datasets using a Likert scale that ranged from 1 to 4, with 4 indicating the best score for the following parameters: sharpness, lesion demarcation, artifacts, overall image quality, and diagnostic confidence. Additionally, the image preference of the readers and the interreader agreement were assessed. The average age of the patients was 63±11years. FLAIRDLR exhibited significantly less image noise than FLAIRS, with P-values of<.001 and<.05, respectively. The sharpness of the images and the ability to detect lesions were rated higher in FLAIRDLR, with a median score of 4 compared to a median score of 3 in FLAIRS (P-values of<.001 for both readers). In terms of overall image quality, FLAIRDLR was rated superior to FLAIRS, with a median score of 4 vs 3 (P-values of<.001 for both readers). Both readers preferred FLAIRDLR in 68/70 cases. The feasibility of deep learning FLAIR brain imaging was shown with additional 38% reduction in examination time compared to standard FLAIR imaging. Furthermore, this technique has shown improvement in image quality, noise reduction, and lesion demarcation.

Microstructural white matter biomarkers of symptom severity and therapy outcome in catatonia: Rationale, study design and preliminary clinical data of the whiteCAT study

The number of magnetic resonance imaging (MRI) studies on neuronal correlates of catatonia has dramatically increased in the last 10 years, but conclusive findings on white matter (WM) tracts alterations underlying catatonic symptoms are still lacking. Therefore, we conduct an interdisciplinary longitudinal MRI study (whiteCAT) with two main objectives: First, we aim to enroll 100 psychiatric patients with and 50 psychiatric patients without catatonia according to ICD-11 who will undergo a deep phenotyping approach with an extensive battery of demographic, psychopathological, psychometric, neuropsychological, instrumental and diffusion MRI assessments at baseline and 12 weeks follow-up. So far, 28 catatonia patients and 40 patients with schizophrenia or other primary psychotic disorders or mood disorders without catatonia have been studied cross-sectionally. 49 out of 68 patients have completed longitudinal assessment, so far. Second, we seek to develop and implement a new method for semi-automatic fiber tract delineation using active learning. By training supportive machine learning algorithms on the fly that are custom tailored to the respective analysis pipeline used to obtain the tractogram as well as the WM tract of interest, we plan to streamline and speed up this tedious and error-prone task while at the same time increasing reproducibility and robustness of the extraction process. The goal is to develop robust neuroimaging biomarkers of symptom severity and therapy outcome based on WM tracts underlying catatonia. If our MRI study is successful, it will be the largest longitudinal study to date that has investigated WM tracts in catatonia patients.

One-stop prostate MRI biopsy service improving the turnaround times from MRI referral to biopsy

Background: Prostate cancer is the most common cancer in men in the UK, with steady increase in the number of magnetic resonance imaging (MRI) referrals and biopsies. In the traditional pathway, there can be substantial delay from referral to biopsy. In our hospital, the interval between MRI and biopsy is between three to eight weeks. This affects the 31/62-day targets of cancer diagnosis and treatment. We introduced a one-stop clinic, the first in Scotland, to reduce the turnaround times.

Need for and predictability of magnetic resonance imaging examinations in patients with implanted neurostimulators

HintergrundBei steigender Zahl von Magnetresonanztomographie(MRT)-Untersuchungen in der deutschen Gesamtbevölkerung gibt es keine Daten zum Untersuchungsbedarf von Patienten mit implantiertem Neurostimulator in Deutschland. Publizierte Daten aus den USA legen einen hohen Bedarf nahe. Die eingeschränkte MRT-Zulassung der Implantate ist in der täglichen Praxis ein häufiges Problem.ZielIm Fokus steht der MRT-Bedarf dieser Schmerzpatienten und die Vorhersagbarkeit zum Zeitpunkt der Implantation.Material und MethodenEs erfolgte eine retrospektive Auswertung der Datenbank unseres Klinikinformationssystems. Gesucht wurden alle im Zeitraum November 2011 bis März 2019 in unserem Klinikum angeforderten MRT-Untersuchungen für Patienten mit implantiertem Neurostimulator. Zudem erfolgte ein Abgleich mit den im gleichen Zeitraum durchgeführten Implantationen derartiger Stimulationssysteme.ErgebnisseEs konnten 171 durchgeführte MRT-Untersuchungen und 22 Anforderungen ohne nachfolgende Untersuchung ausgewertet werden. Bei 83 von 294 Patienten, die in unserem Zentrum mit implantierten Neurostimulatoren versorgt wurden, erfolgte mindestens eine MRT-Untersuchung in unserem Klinikum. Wir beobachten eine stetig steigende Nachfrage. In 111 von 171 durchgeführten Untersuchungen (65 %) bestand kein Zusammenhang zwischen der zur Implantation führenden Indikation und der Indikation für die MRT. Eine Vorhersagbarkeit konnte nur bei 43 von 193 MRT-Anforderungen (22 %) unterstellt werden.DiskussionPatienten mit implantiertem Neurostimulator haben auch in Deutschland einen hohen Bedarf an MRT-Diagnostik, welcher zum Zeitpunkt der Implantation nicht vorhersagbar ist. Daher sollten ausschließlich MRT-taugliche Systeme implantiert werden. Die Industrie ist aufgefordert, die Implantate und deren Zulassungen an den Bedarf anzupassen.

Magnetic Resonance Imaging in Patients With Hearing Implants - Follow-up on Prevalence and Complications.

To examine the number of magnetic resonance imaging (MRI) examinations performed in patients with hearing implants and to quantify side effects or complications related to this procedure. Questionnaire. Tertiary referral center, academic hospital. One thousand four hundred sixty-onepatients with an implanted hearing system. Patients were asked to complete a questionnaire either during a visit to the clinic (304) or by mail contact (1,157) between February 2018 and March 2019. Number of examinations by means of MRI per patient and number of side effects or complications. A total of 711 questionnaires were returned. After excluding nonvalid information on the questionnaire, 12.8% of patients were identified who had undergone an MRI after having received their hearing implant. Within this group of 91 patients, the most common precaution undertaken was a head bandage (69%). Side effects were mainly pain (37%), followed by anxiety (15%) and tinnitus (9%). The MRI had to be aborted in 14% and dislocation of the magnet occurred in 7% of examinations. Our data indicate that patients undergoing hearing implant surgery need better information about the limitations and requirements of MRI. The occurrence of side effects is likely as only half of the patients in our study group were completely free of symptoms. Dislocation of the implant magnet was observed in several cases, hence patients and physicians need to be educated about this potential complication.

The data representativeness criterion: Predicting the performance of supervised classification based on data set similarity.

In a broad range of fields it may be desirable to reuse a supervised classification algorithm and apply it to a new data set. However, generalization of such an algorithm and thus achieving a similar classification performance is only possible when the training data used to build the algorithm is similar to new unseen data one wishes to apply it to. It is often unknown in advance how an algorithm will perform on new unseen data, being a crucial reason for not deploying an algorithm at all. Therefore, tools are needed to measure the similarity of data sets. In this paper, we propose the Data Representativeness Criterion (DRC) to determine how representative a training data set is of a new unseen data set. We present a proof of principle, to see whether the DRC can quantify the similarity of data sets and whether the DRC relates to the performance of a supervised classification algorithm. We compared a number of magnetic resonance imaging (MRI) data sets, ranging from subtle to severe difference is acquisition parameters. Results indicate that, based on the similarity of data sets, the DRC is able to give an indication as to when the performance of a supervised classifier decreases. The strictness of the DRC can be set by the user, depending on what one considers to be an acceptable underperformance.

CBIR aided classification using extreme learning machine with probabilistic scaling in MRI brain image

Abstract An enormous number of magnetic resonance imaging (MRI) brain images were produced in hospitals and several MRI centers. To exploit the diagnosis in MRI brain image, “content-based image retrieval (CBIR)” system is accessed in the MRI brain image database. In this paper, a content-based MRI brain image retrieval system is presented, which is helpful in the medical field to seek a diagnosis in an MRI brain image that is similar to the example given. This paper consists of preprocessing, feature extraction, feature selection, similarity measure, and classification. In the preprocessing phase, the Wiener filter is used to remove the unwanted pixels from an MRI brain image. In the second phase, the features related to MRI brain image are extracted using characteristics of shape, margin, and density of the MRI. In the third stage, the features of MRI brain image were reduced using principal component analysis. CBIR classification is used in this method to gain effectual results. In the first stage, retrieval images are obtained using similarity measures using the similarity between the query image features and the derived trained image features. Finally, the classification stage is an extreme learning machine with probabilistic scaling used to classify the obtained retrieval output image and the query image. The result demonstrates that the proposed CBIR approach is robust and effectual compared with other latest work.

Damage Mechanisms to Oligodendrocytes and White Matter in Central Nervous System Injury: The Australian Context.

Traumatic brain injury (TBI) and spinal cord injury (SCI) present a significant contribution to the global disease burden. White matter tracts are susceptible to both the physical forces of trauma and cascades of pathological secondary degeneration. Oligodendrocytes, the myelinating cells of the central nervous system (CNS), and their precursors are particularly vulnerable cell populations and their disruption results in a loss of white matter, dysmyelination, and poor myelin repair. White matter aberrations in TBI and SCI can be visualized in vivo using a number of magnetic resonance imaging (MRI)-based modalities. Recent advances in diffusion MRI allow researchers to investigate subtle abnormalities in white matter microstructure and connectivity, resting state networks, and metabolic perturbations associated with injury. Damage to oligodendroglia underlies white matter aberrations and occurs as a result of glutamate excitotoxicity, intracellular calcium ion (Ca2+) overload, and oxidative damage to lipids, proteins, and DNA. Structural changes to myelin include myelin decompaction, loosening of myelin lamellae, and disruption to the node of Ranvier complex. Neuronal and functional loss accompany dysmyelination together with an increase in astro- and microgliosis. Remyelination is often partial, and more work is needed to understand deficits in remyelination post-injury to develop strategies to both protect and repair myelin and thereby preserve function. This review covers disruptions to oligodendrocyte function and white matter tract structure in the context of TBI and SCI, with an emphasis on Australian contributions in recognition of the International Neurotrauma Symposium held in Melbourne, Australia in 2020.

Descriptive Analysis of an Interdisciplinary Musculoskeletal Program.

Interdisciplinary musculoskeletal programs address comorbidities confounding musculoskeletal conditions and serve as an alternative to the single provider model. Descriptive analysis of an interdisciplinary musculoskeletal program. Retrospective descriptive analysis of patients enrolled in an interdisciplinary musculoskeletal program. Retrospective subanalysis: cohort of patients enrolled in interdisciplinary program with low back pain compared to historical cohort of patients in a single provider clinic. Academic interdisciplinary musculoskeletal health program. Patients referred to program with at least one follow-up visit over a 2-year period. Interdisciplinary musculoskeletal program involving physiatry, pain anesthesia, nutrition, psychology, rheumatology, sleep medicine, nursing, and physical therapy. Patient Specific Functional Scale (PSFS), Oswestry Low Back Disability Index (ODI), number of magnetic resonance imaging (MRI) scans, computed tomography (CT) scans, opioid prescriptions; Press Ganey scores. One hundred and seventy-three patients were enrolled and had at least one follow-up visit. Twenty-four percent of patients with any musculoskeletal complaint demonstrated clinically significant improvements in total PSFS. Mean improvement in PSFS was + 0.864 (SD 1.94), which was a statistically significant improvement (P = .0005), but not clinically significant. Magnetic resonance imaging was ordered for 5% of patients, and no computed tomography scans were ordered. Six percent of patients received opioid prescriptions. Press Ganey scores: 96% responded favorably in regard to physician communication quality, 86% of patients responded favorably for access to care, and 78% responded favorably for care coordination. 27.8% of patients with low back pain in the interdisciplinary program achieved a significant decrease in their ODI, compared to 26.6% in the single provider clinic (P = .87). Interdisciplinary musculoskeletal programs are a promising model to improve the functioning of patients with musculoskeletal pain and decrease downstream utilization. These programs may be more appropriate for patients at higher risk of developing chronic pain.

Implant clarification : Management in clinical practice

The increasing number of magnetic resonance imaging (MRI) examinations and the increasing number of medical implants lead to an ever-increasing expenditure in implant research, which as a consequence is becoming more time and resource consuming. This review article provides guidelines for optimized implant clarification in clinical practice by means of patient interrogation and the incorporation of implant databases. The technical background of implant interactions is discussed and an outlook on new integrated MRI safety systems is given. The optimization of the implant clarification process integrated into the clinical workflow avoids undesired MRI interactions and enables a safe and economic working procedure for patients.

Disease Knowledge Transfer across Neurodegenerative Diseases.

We introduce Disease Knowledge Transfer (DKT), a novel technique for transferring biomarker information between related neurodegenerative diseases. DKT infers robust multimodal biomarker trajectories in rare neurodegenerative diseases even when only limited, unimodal data is available, by transferring information from larger multimodal datasets from common neurodegenerative diseases. DKT is a joint-disease generative model of biomarker progressions, which exploits biomarker relationships that are shared across diseases. Our proposed method allows, for the first time, the estimation of plausible multimodal biomarker trajectories in Posterior Cortical Atrophy (PCA), a rare neurodegenerative disease where only unimodal MRI data is available. For this we train DKT on a combined dataset containing subjects with two distinct diseases and sizes of data available: 1) a larger, multimodal typical AD (tAD) dataset from the TADPOLE Challenge, and 2) a smaller unimodal Posterior Cortical Atrophy (PCA) dataset from the Dementia Research Centre (DRC), for which only a limited number of Magnetic Resonance Imaging (MRI) scans are available. Although validation is challenging due to lack of data in PCA, we validate DKT on synthetic data and two patient datasets (TADPOLE and PCA cohorts), showing it can estimate the ground truth parameters in the simulation and predict unseen biomarkers on the two patient datasets. While we demonstrated DKT on Alzheimer's variants, we note DKT is generalisable to other forms of related neurodegenerative diseases. Source code for DKT is available online: https://github.com/mrazvan22/dkt.

Vitamin D for the management of multiple sclerosis.

This review is an update of a previously published review, "Vitamin D for the management of multiple sclerosis" (published in the Cochrane Library; 2010, Issue 12). Multiple sclerosis (MS) is characterised by inflammation, demyelination, axonal or neuronal loss, and astrocytic gliosis in the central nervous system (CNS), which can result in varying levels of disability. Some studies have provided evidence showing an association of MS with low levels of vitamin D and benefit derived from its supplementation. To evaluate the benefit and safety of vitamin D supplementation for reducing disease activity in people with MS. We searched the Cochrane Multiple Sclerosis and Rare Diseases of the CNS Specialized Register up to 2 October 2017 through contact with the Information Specialist with search terms relevant to this review. We included references identified from comprehensive electronic database searches and from handsearches of relevant journals and abstract books from conferences. We included randomised controlled trials (RCTs) and quasi-RCTs that compared vitamin D versus placebo, routine care, or low doses of vitamin D in patients with MS. Vitamin D was administered as monotherapy or in combination with calcium. Concomitant interventions were allowed if they were used equally in all trial intervention groups. Two review authors independently extracted data and assessed the methodological quality of studies, while another review author sorted any disagreements. We expressed treatment effects as mean differences (MDs) for continuous outcomes (Expanded Disability Status Scale and number of magnetic resonance imaging (MRI) gadolinium-enhancing T1 lesions), as standardised MDs for health-related quality of life, as rate differences for annualised relapse rates, and as risk differences (RDs) for serious adverse events and minor adverse events, together with 95% confidence intervals (CIs). We identified 12 RCTs enrolling 933 participants with MS; 464 were randomised to the vitamin D group, and 469 to the comparator group. Eleven trials tested vitamin D₃, and one trial tested vitamin D₂. Vitamin D₃ had no effect on the annualised relapse rate at 52 weeks' follow-up (rate difference -0.05, 95% CI -0.17 to 0.07; I² = 38%; five trials; 417 participants; very low-quality evidence according to the GRADE instrument); on the Expanded Disability Status Scale at 52 weeks' follow-up (MD -0.25, 95% CI -0.61 to 0.10; I² = 35%; five trials; 221 participants; very low-quality evidence according to GRADE); and on MRI gadolinium-enhancing T1 lesions at 52 weeks' follow-up (MD 0.02, 95% CI -0.45 to 0.48; I² = 12%; two trials; 256 participants; very low-quality evidence according to GRADE). Vitamin D₃ did not increase the risk of serious adverse effects within a range of 26 to 52 weeks' follow-up (RD 0.01, 95% CI -0.03 to 0.04; I² = 35%; eight trials; 621 participants; low-quality evidence according to GRADE) or minor adverse effects within a range of 26 to 96 weeks' follow-up (RD 0.02, 95% CI -0.02 to 0.06; I² = 20%; eight trials; 701 participants; low-quality evidence according to GRADE). Three studies reported health-related quality of life (HRQOL) using different HRQOL scales. One study reported that vitamin D improved ratings on the psychological and social components of the HRQOL scale but had no effects on the physical components. The other two studies found no effect of vitamin D on HRQOL. Two studies reported fatigue using different scales. One study (158 participants) reported that vitamin D₃ reduced fatigue compared with placebo at 26 weeks' follow-up. The other study (71 participants) found no effect on fatigue at 96 weeks' follow-up. Seven studies reported on cytokine levels, four on T-lymphocyte proliferation, and one on matrix metalloproteinase levels, with no consistent pattern of change in these immunological outcomes. The randomised trials included in this review provided no data on time to first treated relapse, number of participants requiring hospitalisation owing to progression of the disease, proportion of participants who remained relapse-free, cognitive function, or psychological symptoms. To date, very low-quality evidence suggests no benefit of vitamin D for patient-important outcomes among people with MS. Vitamin D appears to have no effect on recurrence of relapse, worsening of disability measured by the Expanded Disability Status Scale (EDSS), and MRI lesions. Effects on health-related quality of life and fatigue are unclear. Vitamin D₃ at the doses and treatment durations used in the included trials appears to be safe, although available data are limited. Seven ongoing studies will likely provide further evidence that can be included in a future update of this review.

Brain morphologic changes in early stages of psychosis: Implications for clinical application and early intervention.

To date, a large number of magnetic resonance imaging (MRI) studies have been conducted in schizophrenia, which generally demonstrate gray matter reduction, predominantly in the frontal and temporo-limbic regions, as well as gross brain abnormalities (e.g., a deviated sulcogyral pattern). Although the causes as well as timing and course of these findings remain elusive, these morphologic changes (especially gross brain abnormalities and medial temporal lobe atrophy) are likely present at illness onset, possibly reflecting early neurodevelopmental abnormalities. In addition, longitudinal MRI studies suggest that patients with schizophrenia and related psychoses also have progressive gray matter reduction during the transition period from prodrome to overt psychosis, as well as initial periods after psychosis onset, while such changes may become almost stable in the chronic stage. These active brain changes during the early phases seem to be relevant to the development of clinical symptoms in a region-specific manner (e.g., superior temporal gyrus atrophy and positive psychotic symptoms), but may be at least partly ameliorated by antipsychotic medication. Recently, increasing evidence from MRI findings in individuals at risk for developing psychosis has suggested that those who subsequently develop psychosis have baseline brain changes, which could be at least partly predictive of later transition into psychosis. In this article, we selectively review previous MRI findings during the course of psychosis and also refer to the possible clinical applicability of these neuroimaging research findings, especially in the diagnosis of schizophrenia and early intervention for psychosis.

Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences.

As the number of magnetic resonance imaging (MRI) scanners and patients with medical implants is constantly growing, radiologists increasingly encounter metallic implant-related artifacts in MRI, resulting in reduced image quality. Therefore, the MRI suitability of implants in terms of artifact volume, as well as the development of pulse sequences to reduce image artifacts, are becoming more and more important. Here, we present a comprehensive protocol which allows for a standardized evaluation of the artifact volume of implants on MRI. Furthermore, this protocol can be used to analyze the vulnerability of different pulse sequences to artifacts. The proposed protocol can be applied to T1- and T2-weighted images with or without fat-suppression and all passive implants. Furthermore, the procedure enables the separate and three-dimensional identification of signal loss and pile-up artifacts. As previous investigations differed greatly in evaluation methods, the comparability of their results was limited. Thus, standardized measurements of MRI artifact volumes are necessary to provide better comparability. This may improve the development of the MRI suitability of implants and better pulse sequences to finally improve patient care.

Cytokine Response, Tract-Specific Fractional Anisotropy, and Brain Morphometry in Post-Stroke Cognitive Impairment

Post-stroke cognitive impairment is a clinically heterogeneous condition and its types have a different course and prognosis. The aim of the present study is to address the roles of inflammation, white matter pathology, and brain atrophy in different neuropsychological types of cognitive impairment in the acute period of ischemic stroke. In 92 patients, we performed an assessment of the cognitive status and measured concentrations of cytokines (interleukin [IL]-1β, IL-6, tumor necrosis factor-alpha, IL-10) in liquor and serum, as well as a number of magnetic resonance imaging (MRI) morphometric parameters and fractional anisotropy. The control group consisted of 14 individuals without cerebrovascular disease. All patients had a higher level of IL-10 in serum than the control group. Patients with dysexecutive cognitive impairment had a higher concentration of IL-1β and IL-10 in liquor, IL-6 level in serum, and a lower fractional anisotropy of the ipsilateral thalamus than patients with normal cognition. Patients with mixed cognitive impairment were characterized by a lower fractional anisotropy of contralateral fronto-occipital fasciculus, compared with patients with dysexecutive cognitive impairment. Patients with both dysexecutive and mixed cognitive deficit had a wide area of leukoaraiosis and a reduced fractional anisotropy of the contralateral cingulum, compared with patients without cognitive impairment. Also, we found numerous correlations between cognitive status and levels of cytokines, MRI morphometric parameters, and fractional anisotropy of certain regions of the brain. The concentrations of cytokines in serum and cerebrospinal fluid studied in combination with MRI morphometric parameters and fractional anisotropy appear to be informative biomarkers of clinical types of post-stroke cognitive impairment.

Risk stratification of patients with suspected TIA or minor stroke in the initial triage: The combat-TIA study

Background: People with transient ischemic attack (TIA) are at high risk of early stroke, which can be as high as 3.5% within 48 hours and 5.2% within 7 days. Urgent assessment and intervention reduces the risk of stroke after TIA. Japan has the highest number of magnetic resonance imaging (MRI) units in the world and citizens can freely access any hospital.

Structural Brain Network Changes across the Adult Lifespan.

A number of magnetic resonance imaging (MRI) studies have shown age-related alterations in brain structural networks in different age groups. However, the specific age-associated changes in brain structural networks across the adult lifespan is underexplored. In the current study, we performed a multivariate independent component analysis (ICA) to identify structural brain networks based on covariant gray matter volume and then investigated the age-related trajectories of structural networks over the adult lifespan in 536 healthy subjects aged 20–86 years. Twenty independent components (ICs) were extracted in the ICA, and statistical analyses between age and ICA weights revealed 16 age-related ICs across the adult lifespan. Most of the trajectories of ICA weights demonstrated significant linear decline tendencies, and the corresponding structural networks primarily included the anterior and posterior dorsal attention networks, the ventral and posterior default mode networks, the auditory network, five cerebellum networks and the hippocampus-related network with the most significant decreased tendency among all ICs (p of age = 1.11E-77). Only the temporal lobe-related network showed a significant quadratic tendency with age (p of age2 = 5.66E-06). Our findings not only provide insight into the patterns of the age-related changes of structural networks but also provide a foundation for understanding abnormal aging.

Assessment of the Accuracy of Optical Shape Sensing for Needle Tracking Interventions

Accurate needle guidance is essential for a number of magnetic resonance imaging (MRI)-guided percutaneous procedures, such as radiofrequency ablation (RFA) of metastatic liver tumors. A promising technology to obtain real-time tracking of the shape and tip of a needle is by using high-frequency (up to 20 kHz) fiber Bragg grating (FBG) sensors embedded in optical fibers, which are insensitive to external magnetic fields. We fabricated an MRI-compatible needle designed for percutaneous procedures with a series of FBG sensors which would be tracked in an image-guidance system, allowing to display the needle shape within a navigation image. A series of phantom experiments demonstrated needle tip tracking errors of 1.05 ± 0.08 mm for a needle deflection up to 16.82 mm on a ground-truth model and showed nearly similar accuracy to electromagnetic (EM) tracking (i.e., 0.89 ± 0.09 mm). We demonstrated feasibility of the FBG-based tracking system for MRI-guided interventions with differences under 1 mm between tracking systems. This study establishes the needle tracking accuracy of FBG needle tracking for image-guided procedures.

Design considerations and experimental results for MRI systems using HTS magnets

An increasing number of magnetic resonance imaging (MRI) systems using high temperature superconductors (HTS) magnets have been designed and constructed, with detailed results of their performance now available. Features of REBCO and BSCCO conductors are described as they pertain to use in high homogeneity magnets, with emphasis placed on the practical use of these conductors in magnets. Methods of coil winding are discussed, in particular the differences between pancake and layer winding techniques. Design considerations for HTS magnets are presented in light of the difficulties presented by quench in these magnets, but also in terms of the features of HTS magnets afforded by their high operating temperatures, namely robust cryogen free operation and the potential to use unshielded gradient coils. Drawing on two example MRI systems, namely a 3 T BSCCO brain imaging magnet developed in Japan and a 1.5 T REBCO orthopaedic imaging system developed in New Zealand, the report details real-world stability and homogeneity of HTS-MRI systems, in particular with regards to the screening current effects observed in these systems. It is concluded that, apart from conductor cost, there are currently no technical obstacles to use of HTS-MRI systems.

ADHD and Cerebellar Vermis Tumor: DTI Analysis of an Incidental Finding

The increase in number of magnetic resonance imaging (MRI) scans for investigation of neurological diseases in childhood and adolescence leads to increase of incidental findings of central nervous system (CNS) tumors in these stages of life. Among MRI techniques, diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) have been increasingly used in brain studies. These images are based on random motion of water molecules in the body, which can change depending on constitution and geometry of biological tissues, as well as the existence of pathologies. This paper reports the use of DTI and DWI to evaluation of a CNS tumor incidentally detected in a patient diagnosed previously with Attention Deficit Hyperactivity Disorder (ADHD). He was diagnosed at age 9 and has been treated with medicines and psycho-pedagogical therapies. At age 15 a MRI detected a cerebellar vermis tumor with a volume of 2 cm 3 . Due to parental decision, the patient did not undergo any surgical intervention. During the follow-up period we did not observe significant changes in tumor size or diffusion directions in the tumor and surrounding brain tissues. The main brain tracts presented normal diffusion patterns, both in terms of size and geometry. The DTI analysis showed that lesion was quite homogeneous and isotropic, with no significant restriction of diffusion. There also were no significant diffusion pattern changes in other regions of the brain which possibly could be related to ADHD. So, given the characteristics of lesion and the patient's clinical symptoms, it cannot be directly related to ADHD.