[Von-Hippel-Lindau disease Type IIa with hypertensive crisis].
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Diagnosis, Differential↗
Biomedical subjects
F L Giesel
Publications and source records attributed to F L Giesel.
An optimized workflow for the integration of biological information into radiotherapy planning: experiences with T1w DCE-MRI.
Planning of radiotherapy is often difficult due to restrictions on morphological images. New imaging techniques enable the integration of biological information into treatment planning and help to improve the detection of vital and aggressive tumour areas. This might improve clinical outcome. However, nowadays morphological data sets are still the gold standard in the planning of radiotherapy. In this paper, we introduce an in-house software platform enabling us to combine images from different imaging modalities yielding biological and morphological information in a workflow driven approach. This is demonstrated for the combination of morphological CT, MRI, functional DCE-MRI and PET data. Data of patients with a tumour of the prostate and with a meningioma were examined with DCE-MRI by applying pharmacokinetic two-compartment models for post-processing. The results were compared with the clinical plans for radiation therapy. Generated parameter maps give additional information about tumour spread, which can be incorporated in the definition of safety margins.
Algorithms↗
[Unusual course of alpha-mannosidosis with symptoms of paranoid-hallucinatory psychosis].
We report the case of a 27-year-old female with recurrent paranoid-hallucinatory episodes who was initially diagnosed as suffering from schizophrenic psychosis. After 10 years of treatment under this diagnosis, alpha-mannosidosis was identified to be the underlying cause of her psychiatric symptoms. alpha-Mannosidosis is a rare autosomal recessive lysosomal storage disorder associated with decreased activity of the enzyme mannosidase. In the present case, diagnosis was made late in the illness after failure of a response to antipsychotic treatment and with the patient additionally showing progressive cognitive decline. Only after extensive investigation was the diagnosis made by showing decreased alpha-mannosidase enzyme activity in serum and blood leukocytes. This case demonstrates that an unusual clinical course or striking symptom patterns, especially in association with somatic comorbidity, in psychotic patients should lead to diagnostic consideration of inherited metabolic disease.
Adult↗
[Perfusion measurement using the T2* contrast media dynamics in neuro-oncology. Physical basics and clinical applications].
Perfusion imaging in the central nervous system (CNS) is mostly performed using the first-pass dynamic susceptibility-weighted contrast-enhanced (DSC) MRI. The first-pass of a contrast bolus in brain tissue is monitored by a series of T2*-weighted MR images. The susceptibility effect of the paramagnetic contrast agent leads to a signal loss that can be converted, using the principles of the indicator dilution theory, into an increase of the contrast agent concentration. From these data, parameter maps of cerebral blood volume (CBV) and flow (CBF) can be derived. Regional CBF and CBV values can be obtained by region-of-interest analysis. This review article describes physical basics of DSC MRI and summarizes the literature of DSC MRI in neurooncological issues.Studies, all with relatively limited patient numbers, report that DSC MRI is useful in the preoperative diagnosis of gliomas, CNS-lymphomas, and solitary metastases, as well as in the differentiation of these neoplastic lesions from infections and tumor-like manifestations of demyelinating disease. Additionally, DSC MRI is suitable for determining glioma grade and regions of active tumor growth which should be the target of stereotactic biopsy. After therapy, DSC MRI helps better assessing the tumor response to therapy, residual tumor after therapy, and possible treatment failure and therapy-related complications, such as radiation necrosis. The preliminary results show that DSC MRI is a diagnostic tool depicting regional variations in microvasculature of normal and diseased brains.
Algorithms↗
[Methodological principles for optimising functional MR experiments].
Functional magnetic resonance imaging (fMRI) is one of the most common methods for localising neuronal activity in the brain. Even though the sensitivity of fMRI is comparatively low, the optimisation of certain experimental parameters allows obtaining reliable results. In this article, approaches for optimising the experimental design, imaging parameters and analytic strategies will be discussed. Clinical neuroscientists and interested physicians will receive practical rules of thumb for improving the efficiency of brain imaging experiments.
Algorithms↗
[Working memory in healthy subjects and schizophrenics: studies using BOLD fMRT].
Functional magnetic resonance imaging uses the blood oxygen level-dependent effect (BOLD MRI) for noninvasive display of cerebral correlatives of cognitive function. The importance for the understanding of physiological and pathological processes is demonstrated by investigations of working memory in schizophrenics and healthy controls. Working memory is involved in processing rather than storage of information and therefore is linked to complex processes such as learning and problem solving. In schizophrenic psychosis, these functions are clearly restricted. Training effects in the working memory task follow an inverse U-shape function, suggesting that cerebral activation reaches a peak before economics of the brain find a more efficient method and activation decreases.
Brain↗
[MR-based methods of the functional imaging of the central nervous system].
This review presents the basic principles of functional imaging of the central nervous system utilizing magnetic resonance imaging. The focus is set on visualization of different functional aspects of the brain and related pathologies. Additionally, clinical cases are presented to illustrate the applications of functional imaging techniques in the clinical setting. The relevant physics and physiology of contrast-enhanced and non-contrast-enhanced methods are discussed. The two main functional MR techniques requiring contrast-enhancement are dynamic T1- and T2*-MRI to image perfusion. Based on different pharmacokinetic models of contrast enhancement diagnostic applications for neurology and radio-oncology are discussed. The functional non-contrast enhanced imaging techniques are based on "blood oxygenation level dependent (BOLD)-fMRI and arterial spin labeling (ASL) technique. They have gained clinical impact particularly in the fields of psychiatry and neurosurgery.
Animals↗
[Noninvasive measurement of relative cerebral blood flow with the blood bolus MRI arterial spin labeling: basic physics and clinical applications].
Knowledge of tumor blood flow is important for diagnosis and follow-up of brain tumors after therapy, especially to discriminate necrosis from tumor recurrence after radiation or chemotherapy. Meanwhile, perfusion and diffusion MRI, besides MR-angiography, are state of the art in stroke imaging. Until now, perfusion imaging was mostly performed using the first-pass dynamic susceptibility-weighted contrast-enhanced (DSC) MRI. The MRI-based arterial spin labeling technique (ASL) is a novel approach for measuring relative cerebral blood flow (rCBF) without using extrinsic contrast agents, by labeling spins of flowing arterial blood as intrinsic contrast agent. This article describes physical basics of ASL and shows clinical examples in neuroimaging such as in meningeoma, glioblastoma, oligodendroglioma, and cerebral ischemia, using the Q2TIPS ASL technique. Gray matter is clearly visible, while the observed white matter signal obtained by Q2TIPS is only slightly higher than background noise. Venous blood causes artefacts in the sagittal sinus and other large superficial veins in the subarachnoid space. Meningeoma and glioblastoma show elevated rCBF, whereas oligodendroglioma and cerebral ischemia have reduced rCBF values. Arterial-spin-labeling techniques are noninvasive tools for measuring rCBF within 5 min, using a standard MRI scanner.
Blood Flow Velocity↗
[Unilateral eyelid swelling after a simple nose blowing].
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Adult↗
[Physiological and technical limitations of functional magnetic resonance imaging (fMRI)--consequences for clinical use].
Functional magnetic resonance imaging (fMRI) is the most common noninvasive technique in functional neuroanatomy. The capabilities and limitations of the method will be discussed based on a short review of the current knowledge about the neurovascular relationship. The focus of this article is on current methodical and technical problems regarding fMRI-based detection and localization of neuronal activity. Main error sources and their influence on the reliability and validity of fMRI-methods are presented. Appropriate solution strategies will be proposed and evaluated. Finally, the clinical relevance of MR-based diagnostic methods are discussed.
Brain Diseases↗
[Functional magnetic resonance imaging and dementia].
Currently, different cerebral neuroimaging methods are being applied to varying questions in the diagnosis of dementia. In patients with manifest Alzheimer's disease a reduction of cortical perfusion and metabolism in temporal and temporoparietal regions has been demonstrated when compared to healthy controls on a diversity of memory tasks. Since differing levels of performance and varying degrees of cortical atrophy may influence functional results considerably, an understanding of the processes associated with normal ageing is perceived as prerequisite for studies applying functional neuroimaging. The integration of knowledge concerning neuropsychological and neurobiological alterations associated with healthy ageing allows hypotheses for the differentiation of pathological ageing processes to be phrased. In this connection non-invasive methods such as fMRI and ASL are of increasing importance.
Adult↗
Dynamic contrast-enhanced magnetic resonance imaging in oncology.
Dynamic contrast-enhanced MRI (DCE-MRI) is the acquisition of sequential images during the passage of a contrast agent within a tissue of interest. The current gadolinium chelate agents enable visualization of lesion vasculature and, due to their small size, can be used to assess vascular permeability. Recent studies demonstrated that the temporal evolution of gadolinium-induced signal intensity changes within a tumor reflects the angiogenic properties of the tumor. These can be quantified and are related to vascular density and other angiogenic characteristics of lesions, such as the level of vascular endothelial growth factor. DCE-MRI provides noninvasive characterization of antiangiogenic response of tumor during therapeutic intervention to monitor and predict response. This article reviews the fundamental pathophysiological basis of DCE-MRI and the technical aspects necessary for successful implementation DCE-MRI. The role of DCE-MRI in tumor detection, characterization, and therapy monitoring is reviewed.
Contrast Media↗
Bile-tagged 3d magnetic resonance colonography after exclusive intravenous administration of gadobenate dimeglumine, a contrast agent with partial hepatobiliary excretion.
RATIONALE AND OBJECTIVES: Imaging of the colon is an important diagnostic procedure. Endoscopic colonoscopy and x-ray barium enemas are currently the standard diagnostic procedures. Magnetic resonance (MR) and computed tomographic colonography have been recently introduced with true three-dimensional (3D) cross-sectional imaging. Up to now, all imaging techniques have required the use of oral and/or aboral contrast agents for luminal enhancement and commonly, a relaxation medication (glucagon or N-butylscopolamine). While performing several phase I, II, and III studies with a new partially hepatobiliary excreted gadolinium-based MR contrast agent, we noted substantial intraluminal enhancement within the colon and investigated its potential for imaging. METHODS: Three-dimensional MR angiographic techniques enable imaging of large volumes. We have used these sequences to detect contrast enhancement within the hepatobiliary and gastrointestinal systems. A 3D volume of 40 x 32 x 12 cm with 42 images was acquired under breath-hold. Six volunteers were studied according to the protocol. No bowel preparation was performed and no medication given. Subsequent follow-ups of the abdomen were performed at 1, 12, 24, 36, 48, 70, and 105 hours postinjection. Gadobenate dimeglumine at 0.1 mmol/kg body weight was given intravenously. Images were assessed quantitatively and by blinded reader analysis. RESULTS: Intense intraluminal contrast enhancement within the colon was seen within 24 hours in all subjects. The homogeneous enhancement was of sufficient intensity to enable 3D visualization and virtual endoscopy. The optimal time window for imaging was determined to be 16 to 50 hours postinjection. CONCLUSIONS: We report for the first time the feasibility of exclusively bile-tagged MR colonography with the use of only an intravenous MR contrast that exhibits partial hepatobiliary excretion. This new diagnostic procedure will enable not only morphological assessment of the colon but also functional and pathophysiological studies on the transport kinetics of bile and stool without any preparation of the patient.
Adult↗