Use Of Functional Imaging Techniques Research Articles

New Enclosure for in vivo Medical Imaging of Zebrafish With Vital Signs Monitoring.

Lately, the use of zebrafish has gained increased interest in the scientific community as an animal model in preclinical research. However, there is a lack of in vivo imaging tools that ensure animal welfare during acquisition procedures. The use of functional imaging techniques, like Positron Emission Tomography (PET), in zebrafish is limited since it requires the animal to be alive, representing a higher instrumentation complexity when compared to morphological imaging systems. In the present work, a new zebrafish enclosure was developed to acquire in vivo images while monitoring the animal’s welfare through its heartbeat. The temperature, dissolved oxygen, and pH range in a closed aquatic environment were tested to ensure that the conditions stay suitable for animal welfare during image acquisitions. The developed system, based on an enclosure with a bed and heartbeat sensors, was tested under controlled conditions in anesthetized fishes. Since the anesthetized zebrafish do not affect the water quality over time, there is no need to incorporate water circulation for the expected time of PET exams (about 30 min). The range of values obtained for the zebrafish heart rate was 88–127 bpm. The developed system has shown promising results regarding the zebrafish’s heart rate while keeping the fish still during the long imaging exams. The zebrafish enclosure ensures the animal’s well-being during the acquisition of in vivo images in different modalities (PET, Computer Tomography, Magnetic Resonance Imaging), contributing substantially to the preclinical research.

Functional and anatomical imaging in pediatric oncology: which is best for which tumors.

Functional imaging techniques are playing an increasingly important role in the management of pediatric cancer. Technological advances have pushed the development of hybrid imaging techniques, including positron emission tomography (PET)/CT, PET/MR and single-photon emission computed tomography (SPECT)/CT. Together with an increasing need to identify surrogate biomarkers for response to novel therapies, the use of functional imaging techniques, which had been reserved primarily for lymphoma patients, is now being recognized as standard of care for the management of many other pediatric solid tumors. The purpose of this review is to summarize recent data describing the use of functional and metabolic imaging strategies for the staging and response assessment of common pediatric solid tumors, and to offer some guidance as to which techniques are most appropriate for which tumor types.

Imaging in myeloma with focus on advanced imaging techniques.

In recent years, there have been major advances in the imaging of myeloma with whole body MRI incorporating diffusion-weighted imaging, emerging as the most sensitive modality. Imaging is now a key component in the work-up of patients with a suspected diagnosis of myeloma. The International Myeloma Working Group now specifies that more than one focal lesion on MRI or lytic lesion on whole body low-dose CT or fludeoxyglucose (FDG) PET/CT fulfil the criteria for bone damage requiring therapy. The recent National Institute for Health and Care Excellence myeloma guidelines recommend imaging in all patients with suspected myeloma. In addition, there is emerging data supporting the use of functional imaging techniques (WB-DW MRI and FDG PET/CT) to predict outcome and evaluate response to therapy. This review summarises the imaging modalities used in myeloma, the latest guidelines relevant to imaging and future directions.

Network Imaging in Parkinsonian and Other Movement Disorders: Network Dysfunction and Clinical Correlates.

Parkinson's disease (PD) is classically defined as a disease of progressive dopaminergic dysfunction, thus explaining many of the levodopa-responsive motor features. However, even early in the disease, non-motor symptoms can appear, affecting sleep, cognition, and behavior. This implies the involvement of more widespread circuitry beyond the basal ganglia. In addition, the varied clinical presentation and the clinical overlap between PD and other diseases of dopamine degeneration (referred to as atypical parkinsonian syndromes), particularly early in the disease, have complicated diagnosis, treatment, and clinical trials. The increased use of functional imaging techniques, which can identify and quantify widespread functional networks, has provided insights into understanding these disorders beyond dopaminergic degeneration. In this chapter, we summarize such work as it relates to pathophysiology, diagnosis, progression, and treatment of parkinsonian disorders. We also briefly highlight findings in another neurodegenerative disorder, Huntington's disease.

Whole-body MRI in paediatric oncology.

Imaging plays a crucial role in the diagnosis and follow-up of paediatric malignancies. Until recently, computed tomography (CT) has been the imaging technique of choice in children with cancer, but nowadays there is an increasing interest in the use of functional imaging techniques like positron emission tomography and single-photon emission tomography. These later techniques are often combined with CT allowing for simultaneous acquisition of image data on the biological behaviour of tumour, as well as the anatomical localisation and extent of tumour spread. Because of the small but not negligible risk of radiation induced secondary cancers and the significantly improved overall survival rates of children with cancer, there is an increasing interest in the use of alternative imaging techniques that do not use ionising radiation. Magnetic resonance imaging (MRI) is a radiation-free imaging tool that allows for acquiring images with a high spatial resolution and excellent soft tissue contrast throughout the body. Moreover, recent technological advances have resulted in fast diagnostic sequences for whole-body MR imaging (WB-MRI), including functional techniques such as diffusion weighted imaging. In this review, the current status of the technique and major clinical applications of WB-MRI in children with cancer will be discussed.

Fatigue in patients with multiple sclerosis--pathogenesis, clinical picture, diagnosis and treatment

Fatigue is a frequent and restricting symptom of multiple sclerosis (MS). Starting from its pathogenetic mechanisms, the article develops an approach to the differential diagnosis of fatigue in MS patients. Over the past years, the use of functional imaging techniques has given important information on the mechanisms of this highly variable clinical picture. Considering our improved understanding of the interdependency of immune pathology and the clinical presentation of neuropsychological disorders, the relationship between immunomodulatory treatments and fatigue is receiving increased attention. Therefore, this article not only reports on the most recent data on pharmacological, physical and psychological interventions in the symptomatic treatment of fatigue, but also puts a special accent on data concerning the interactions between the rapidly growing number of immunomodulatory treatments in MS.

Corticospinal tract mapping in children with ruptured arteriovenous malformations using functionally guided diffusion-tensor imaging

Arteriovenous malformations (AVMs) can lead to distortion or reorganization of functional brain anatomy, making localization of eloquent white matter tracts challenging. To improve the accuracy of corticospinal tract (CST) mapping, recent studies have examined the use of functional imaging techniques to help localize cortical motor activations and use these as seed points to reconstruct CSTs using diffusion-tensor imaging (DTI). The authors examined the role of pretreatment functionally guided DTI CST mapping in 3 children with ruptured AVMs. In 2 patients, magnetoencephalography motor activations were adjacent to the nidus and/or hemorrhagic cavity. However, in 1 child, functional MRI motor activations were detected in both hemispheres, suggestive of partial transfer of cortical motor function. In all children, quantitative analysis showed that fractional anisotropy values and fiber density indices were reduced in the CSTs of the hemisphere harboring the AVM compared with the unaffected side. In 2 children, CST caliber was slightly diminished, corresponding to no motor deficit in 1 patient and a temporary motor deficit in the other. In contrast, 1 child demonstrated marked reduction and displacement of the CSTs, correlating with severe motor deficit. Preoperative motor tractography data were loaded onto the intraoperative neuronavigation platform to guide complete resection of the AVM in 2 cases without permanent neurological deficits. These preliminary results confirm the feasibility of CST mapping in children with ruptured AVMs using functionally guided DTI tractography. Prospective studies are needed to assess the full value of this technique in the risk stratification, prognosis, and multimodality management of pediatric AVMs.

AGENT-BASED SOCIAL PSYCHOLOGY: FROM NEUROCOGNITIVE PROCESSES TO SOCIAL DATA

Moral Foundation Theory states that groups of different observers may rely on partially dissimilar sets of moral foundations, thereby reaching different moral valuations. The use of functional imaging techniques has revealed a spectrum of cognitive styles with respect to the differential handling of novel or corroborating information that is correlated to political affiliation. Here we characterize the collective behavior of an agent-based model whose inter individual interactions due to information exchange in the form of opinions are in qualitative agreement with experimental neuroscience data. The main conclusion derived connects the existence of diversity in the cognitive strategies and statistics of the sets of moral foundations and suggests that this connection arises from interactions between agents. Thus a simple interacting agent model, whose interactions are in accord with empirical data on conformity and learning processes, presents statistical signatures consistent with moral judgment patterns of conservatives and liberals as obtained by survey studies of social psychology.

Advanced Contrast-Enhanced MR Imaging of the CNS

One of the most frequent uses of magnetic resonance imaging (MRI) since its introduction has been in the assessment of the CNS for neoplasm. In recent years there has been a substantial improvement in the MR protocol for tumors that includes the use of functional imaging techniques. As shown in multiple experimental and clinical studies an optimized use of high quality contrast media and the introduction of these functional MRI methods has improved the detection and delineation of CNS tumors. This results not only in more confident diagnoses, but also in a substantially improved differential diagnostic process. The article reviews and summarizes the technical advances in functional techniques and their impact on the assessment of cerebral pathologies, namely brain tumors, and gives practical information on how to optimize sequence parameters to achieve the optimal tissue and pathology contrast.

Relationship between structural changes and hyperpolarized gas magnetic resonance imaging in chronic obstructive pulmonary disease using computational simulations with realistic alveolar geometry

Both the development of accurate models of lung function and their quantitative validation can be significantly enhanced by the use of functional imaging techniques. The advent of hyperpolarized noble gas magnetic resonance imaging (MRI) technology has increased the amount of local, functional information we can obtain from the lung. In particular, application of (3)He to measure apparent diffusion coefficients has enabled some measure of lung microstructure and airspace size within the lung. Models mimicking image acquisition in hyperpolarized gas MRI can improve understanding of the relationship between image findings and lung structure, and can be used to improve the definition of imaging protocols. In this paper, we review the state of the art in hyperpolarized gas MRI modelling. We also present our own results, obtained using a Monte Carlo approach and a realistic alveolar sac geometry, which has previously been applied in functional lung studies. In this way, we demonstrate the potential for models combining lung function and image acquisition, which could provide valuable tools in both basic studies and clinical practice.

Aspects radiologiques des métastases des cancers urologiques

Metastases from cancers in urology do not exhibit specific radiological patterns that would allow identification of the primary site. Their detection relies upon usual imaging techniques, and mainly contrast-enhanced Computed Tomography (CT) that allows the study of the thorax, the abdomen and the pelvis. Ultrasound imaging, and the up-to-date contrast-enhanced ultrasound imaging, as well as Magnetic Resonance Imaging are used in addition to CT in case of contra indication of iodinated contrast agents or for targeted indications (focal liver lesion characterization, MR lymphography for lymph node metastases...). PET CT is playing an increasing role but its performances remain limited for the detection of urological metastases. New anti-angiogenic drugs are questioning the traditional evaluation of the therapeutic response based on RECIST criteria. They require more and more the use of functional imaging techniques, such as MRI or CT dynamic studies as well as contrast-enhanced ultrasound.

Functional imaging of the human trigeminal system: opportunities for new insights into pain processing in health and disease.

Peripheral inflammation or nerve damage result in changes in nervous system function, and may be a source of chronic pain. A number of animal studies have indicated that central neural plasticity, including sensitization of neurons within the spinal cord and brain, is part of the response to nervous system insult, and can result in the appearance of altered sensation, including pain. It cannot be assumed, however, that data obtained from animal models unambiguously reflects CNS changes that occur in humans. Currently, the only noninvasive approach to determining objective changes in neural processing and responsiveness within the CNS in humans is the use of functional imaging techniques. It is now possible to use functional magnetic resonance imaging (fMRI) to measure CNS activation in the trigeminal ganglion, spinal trigeminal nucleus, the thalamus, and the somatosensory cortex in healthy volunteers, in a surrogate model of hyperalgesia, and in patients with trigeminal pain. By offering a window into the temporal and functional changes that occur in the damaged nervous system in humans, fMRI can provide both insight into the mechanisms of normal and pathological pain and, potentially, an objective method for measuring altered sensation. These advances are likely to contribute greatly to the diagnosis and treatment of clinical pain conditions affecting the trigeminal system (e.g., neuropathic pain, migraine).

Radiologic diagnostics of dementia

Dementia is one of the most common diseases in the elderly population and is getting more and more important with the ageing of the population. A radiologic structural examination with CT or MRI is meanwhile a standard procedure in the diagnostic work up of patients with dementia syndrome. Radiology enables an early diagnosis and a differential diagnosis between different causes of dementia. Because structural changes occur only late in the disease process, a more detailed structural analysis using volumetric techniques or the use of functional imaging techniques is mandatory. These days, structural imaging uses MRI which enables to detect early atrophic changes at the medial temporal lobe with focus on the amygdala hippocampal complex. These changes are also present in the normal ageing process. In patients with Alzheimer's disease, however, they are more rapid and more pronounced. The use of functional imaging methods such as perfusion MRI, diffusion MRI or fMRI allow new insights into the pathophysiologic changes of dementia. The article gives an overview of the current status of structural imaging and an outlook into the potential of functional imaging methods. Detailed results of structural and functional imaging are presented in other articles of this issue.