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Biomedical subjects

Kristina Szabo

Publications and source records attributed to Kristina Szabo.

12 recordsLinked to original sources

Vascular diagnosis and acute stroke: what, when and why not?

Even within the 3-hour time window, the less the delay to thrombolysis, the more likely it is to be effective. Delays caused by unnecessary examinations based on physicians' uncertainty about the relevance of vascular diagnostics must be overcome if acute therapy is to be administered efficiently. Only defined information concerning inclusion and exclusion criteria, a CT or preferably an MRI of the brain and limited additional data should be achieved prior to treatment and as quickly as possible, preferably within 1 h. All other information is to be gathered after the start of treatment, to assess the possible etiology of stroke, to classify the prognosis, and to recognize the possible need for early intervention such as in carotid stenosis. A primary diagnostic approach with MRI-guided treatment decision should be limited to cases with uncertain or 3- to 9-hour time window to improve selection of patients potentially at benefit from specific treatment and stroke unit/ICU care.

Acute Disease↗

Multiparametric MRI and ultrasound findings in patients with internal carotid artery dissection.

In this study, clinical, MRI, and ultrasound findings in 33 patients with 37 MRI-confirmed internal carotid artery dissections (ICADs) were investigated. In 24 of 37 (64.9%) diffusion-weighted MRI (DWI) revealed acute ischemic brain lesions. ICADs with subsequent DWI lesions usually had a concentric position of the mural hematoma (14 of 24; 58.3%). In contrast, ICADs without DWI lesions (13 of 37; 35.1%) demonstrated an eccentric position of the mural hematoma (10 of 13; 76.9%), sometimes without ultrasound abnormality (5 of 13; 38.5%), while nonischemic clinical signs were frequent (11 of 13; 84.6%). A hemodynamic stroke pattern with comparatively large ischemic lesions along the hemodynamic risk zones was noted in 7 of 24 patients (29.2%).

Brain↗

Diffusion-weighted and perfusion MRI demonstrates parenchymal changes in complex partial status epilepticus.

Diffusion-weighted MRI (DWI) and perfusion MRI (PI) have been mainly applied in acute stroke, but may provide information in the peri-ictal phase in epilepsy patients. Both transient reductions of brain water diffusion, namely a low apparent diffusion coefficient (ADC), and signs of hyperperfusion have been reported in experimental and human epilepsy case studies. We studied 10 patients with complex partial status epilepticus (CPSE) with serial MRI including DWI and PI. All patients showed regional hyperintensity on DWI, and a reduction of the ADC in (i) the hippocampal formation and the pulvinar region of the thalamus (six out of 10 patients), (ii) the pulvinar and cortical regions (two out of 10), (iii) the hippocampal formation only (one out of 10), and (iv) the hippocampal formation, the pulvinar and the cortex (one out of 10). In all patients a close spatial correlation of focal hyperperfusion with areas of ADC/DWI change was present. In two patients hyperperfusion was confirmed in additional SPECT (single photon emission computed tomography) studies. All patients received follow-up MRI examinations showing partial or complete resolution of diffusion and perfusion abnormalities depending on the length of the follow-up interval. The clinical course, EEG and SPECT results all indicate that MRI detected changes related to prolonged epileptic activity. Combined PI and DWI can visualize haemodynamic and tissue changes after CPSE in the hippocampus, thalamus and affected cortical regions.

Adult↗

Multiplanar transcranial ultrasound imaging: standards, landmarks and correlation with magnetic resonance imaging.

The purpose of this study was to define a standardized multiplanar approach for transcranial ultrasound (US) imaging of brain parenchyma based on matched data from 3-D US and 3-D magnetic resonance imaging (MRI). The potential and limitations of multiple insonation planes in transverse and coronal orientation were evaluated for the visualization of intracranial landmarks in 60 healthy individuals (18 to 83 years old, mean 41.4 years) with sufficient temporal bone windows. Landmarks regularly visualized even in moderate sonographic conditions with identification rates of >75% were mesencephalon, pons, third ventricle, lateral ventricles, falx, thalamus, basal ganglia, pineal gland and temporal lobe. Identification of medulla oblongata, fourth ventricle, cerebellar structures, hippocampus, insula, frontal, parietal and occipital lobes was more difficult (<75%). We hypothesize that multiplanar transcranial US images, with standardized specification of tilt angles and orientation, not only allow comparison with other neuroimaging modalities, but may also provide a more objective framework for US monitoring of cerebral disease than freehand scanning.

Adolescent↗

Characterization of carotid artery plaques using real-time compound B-mode ultrasound.

BACKGROUND AND PURPOSE: Real-time compound ultrasound imaging is a new technique for improving the image quality of B-mode scanning. We investigated the value of this method for the characterization of atherosclerotic plaques in the internal carotid artery. METHODS: Thirty-two patients (22 men, 10 women; mean age, 75 years) with plaques of the internal carotid artery as identified by high-resolution B-mode scanning were investigated with real-time compound ultrasound imaging with the use of a 5- to 12-MHz dynamic range linear transducer on a duplex scanner. Two independent observers rated plaque morphology according to a standardized protocol. RESULTS: The majority of plaques was classified as predominantly echogenic and as plaques of irregular surface, whereas ulcerated plaques were rarely observed. The interobserver agreement for plaque surface characterization was good for both compound ultrasound (kappa=0.72) and conventional B-mode (kappa=0.65). For the determination of plaque echogenicity, the reproducibility of compound ultrasound (kappa(w)=0.83) was even higher than that of conventional B-mode ultrasound (kappa(w)=0.74). According to a semiquantitative analysis, real-time compound ultrasound was rated superior in the categories plaque texture resolution, plaque surface definition, and vessel wall demarcation. Furthermore, there was a significant reduction of acoustic shadowing and reverberations. CONCLUSIONS: Real-time compound ultrasound is a suitable technique for the characterization of atherosclerotic plaques, showing good general agreement with high-resolution B-mode imaging. This advanced technique allows reduction of ultrasound artifacts and improves the assessment of plaque texture and surface for enhanced evaluation of carotid plaque morphology.

Aged↗

Diffusion-weighted MRI for the "small stuff": the details of acute cerebral ischaemia.

Diffusion-weighted MRI (DWI) has already had a substantial effect on the diagnosis of patients with ischaemic stroke. It provides in vivo pathological information and allows the differentiation of acute stroke from chronic stroke and from non-specific white-matter lesions. The high contrast of the acute DWI lesion against the dark background facilitates the detection of lesions even when they are 1 mm or less in diameter. Small lesions, which are undetectable by other means, include small lacunar infarcts, punctate cortical infarcts, and DWI bright dots in patients with transient ischaemic attacks (TIA). The latter constitute remnants or "footprints" of recent ischaemia and confirm the clinical TIA syndrome as ischaemic. Because of these attributes, DWI not only confirms the clinical diagnosis, but also facilitates the recognition of certain patterns of ischaemia, thereby providing clues to the underlying aetiology. DWI is becoming an important technique for optimum management of patients.

Brain↗

Diffusion and perfusion MRI for the assessment of carotid atherosclerosis.

Atherosclerotic disease of the extracranial vessels is a frequent cause of cerebral ischemia and stroke. Many natural history studies and prospective treatment trials with large patient samples have focused on optimal patient assessment in regard to medical or interventional measures. Clinical decision making nowadays is largely based on the identification, visualization, and grading of the local stenosis, and the identification of neurologic symptoms related to carotid artery stenosis. MRI already has contributed considerably as many surgeons no longer require preoperative conventional contrast angiography but may use the combination of duplex ultrasound studies and MRA for visualization of the pathology. Besides MRA improvements, DWI and PWI are increasingly used in addition to conventional MR contrasts (PD, T2-, T1-weighted MRI) in attempts to gather information on tissue status and the pathophysiology of hemodynamic compromise and cerebral ischemia in patients with carotid artery stenosis. Obtaining background information using this array of MR data may eventually become a basis for optimal risk-benefit assessment in patients with carotid artery stenosis.

Arteriosclerosis↗

Inflammatory leukocyte infiltration in focal cerebral ischemia: unrelated to infarct size.

OBJECTIVE: An inflammatory host response in the ischemically injured brain is well documented. However, its pathophysiological relevance is uncertain. We investigated whether inflammatory leukocyte response in the ischemic brain alters infarct size. METHODS: The cellular inflammatory response to cerebral ischemia in Wistar-derived rats induced by the transient occlusion of the middle cerebral artery with a thread was pharmacologically upmodulated by lipopolysaccharide (LPS) or downmodulated by continuous infusion of carboxylated sialyl Lewis(x) (sLex). The effects of such experimental modulation of focal cerebral leukocyte recruitment on the extent of the resulting infarction were assessed. RESULTS: Compared to control treatments, LPS strongly enhanced (540.5 +/- 504.8 vs. 94.6 +/- 60.6, p < 0.01) and sLex decreased (32.8 +/- 29.1 vs. 97.0 +/- 49.7, p < 0.05) the numbers of neutrophils at the investigated sites in cerebral ischemia. Unexpectedly, despite such marked experimental modulation of leukocyte infiltration in the ischemic brain, the extent of the resulting cerebral infarction (percent of total hemisphere) remained unchanged under these different conditions (54.5 +/- 10.8 vs. 53.0 +/- 19.1, n.s. and 50.3 +/- 18.0 vs. 57.2 +/- 10.0, n.s., respectively). CONCLUSIONS: The striking dissociation between the massively altered inflammatory leukocyte infiltration in the ischemic brain and the unchanged infarct outcome indicates that intracerebral inflammatory leukocyte recruitment is not a major pathogenic factor in the development of ischemic tissue damage.

Animals↗