RESUMO
A new migration assay, the time-lapse individual cell migration assay (TIM-assay), was developed, which allows the observation of cells over 24 h under controlled conditions. Using this technique, the migratory behavior of 8 human glioblastoma cell lines in vitro was studied. Special features are simultaneous documentation of migratory parameters of individual cells, i.e., migration velocities and migration paths of individual cells. Migration velocity for cell populations of the same cell line ranged from 0 to 24 microm/h. The migration paths were examined for being directional. Two thirds of all cells showed directional migration. Migration paths were further classified according to visual judgements for being linear, oscillating or mixed. The migration index had a mean of 91%. The presented TIM-assay allows the assessment of several new parameters. that may be useful to identify subgroups of gliomas with different biological characteristics.
Assuntos
Neoplasias Encefálicas/patologia , Movimento Celular , Glioma/patologia , Microscopia de Vídeo/métodos , Adulto , Idoso , Feminino , Homeostase , Humanos , Concentração de Íons de Hidrogênio , Cinética , Masculino , Invasividade Neoplásica , Concentração Osmolar , Temperatura , Células Tumorais CultivadasRESUMO
For application in magnetic resonance (MR) guided stereotactic neurosurgery, two methods for transformation of MR-image coordinates in stereotactic, frame-based coordinates exist: the direct stereotactic fiducial-based transformation method and the indirect anatomical landmark method. In contrast to direct stereotactic MR transformation, indirect transformation is based on anatomical landmark coregistration of stereotactic computerized tomography and non-stereotactic MR images. In a patient study, both transformation methods have been investigated with visual inspection and mutual information analysis. Comparison was done for our standard imaging protocol, including t2-weighted spin-echo as well as contrast enhanced t1-weighted gradient-echo imaging. For t2-weighted spin-echo imaging, both methods showed almost similar and satisfying performance with a small, but significant advantage for fiducial-based transformation. In contrast, for t1-weighted gradient-echo imaging with more geometric distortions due to field inhomogenities and gradient nonlinearity than t2-weighted spin-echo imaging, mainly caused by a reduced bandwidth per pixel, anatomical landmark transformation delivered markedly better results. Here, fiducial-based transformation yielded results which are intolerable for stereotactic neurosurgery. Mean Euclidian distances between both transformation methods were 0.96 mm for t2-weighted spin-echo and 1.67 mm for t1-weighted gradient-echo imaging. Maximum deviations were 1.72 mm and 3.06 mm, respectively.
Assuntos
Algoritmos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Técnicas Estereotáxicas , Técnica de Subtração , Cirurgia Assistida por Computador/métodos , Humanos , Neuronavegação/métodos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
PURPOSE: To assess the capability of the computer assisted detection (CAD) system to classify calcifications that are histologically verified as malignant and benign or are proven benign by magnification and follow up mammography. MATERIALS AND METHODS: Three groups of microcalcifications (MC) with and without associated masses were enrolled in the study. The cancer group included 141 screen-detected breast cancer cases. One benign group comprised 109 cases with histologically benign specimens obtained through a minimally invasive breast biopsy. A second benign group included 72 lesions with MC that appeared benign on magnification/compression views and were confirmed to be benign on follow-up mammograms over a period of at least 1.5 years. All mammograms were evaluated with a CAD system (Second Look version 3.5, CADx Medical Systems, Canada). RESULTS: CAD correctly detected 125 of 141 (89 %) cancer cases. Of the 16 false negative cases, CAD marked the location of the MC (which were associated with malignant mass) with a mass mark in 12 cases. For benign cases, CAD did not correctly mark the microcalcifications in 59 of the 109 lesions confirmed benign histologically (54.1 %) and in 39 of the 72 lesions established benign mammographically (54.2 %). Adenosis introduced the highest rate of falsely marked microcalcifications (62 %). CONCLUSION: Due to its limited specificity, CAD can still not be recommended for the primary classification of microcalcifications as malignant or benign. Nevertheless, the low false negative rate and rather high detection rate of malignant findings indicate some value of CAD for an independent second reading.
Assuntos
Doenças Mamárias/diagnóstico por imagem , Neoplasias da Mama/diagnóstico por imagem , Mamografia , Interpretação de Imagem Radiográfica Assistida por Computador , Adenocarcinoma/diagnóstico por imagem , Adenocarcinoma Mucinoso/diagnóstico por imagem , Biópsia , Mama/patologia , Doenças Mamárias/patologia , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/diagnóstico por imagem , Carcinoma Lobular/diagnóstico por imagem , Carcinoma Papilar/diagnóstico por imagem , Diagnóstico Diferencial , Feminino , Fibroadenoma/diagnóstico por imagem , Doença da Mama Fibrocística/diagnóstico por imagem , Fibrose/diagnóstico por imagem , Humanos , Hiperplasia , Papiloma/diagnóstico por imagem , Estudos RetrospectivosRESUMO
In placebo-controlled trials, the overall incidence of nonconvulsive status epilepticus was no higher in the tiagabine-treated group than in the placebo-group. Case reports of nonconvulsive status epilepticus under tiagabine suggested a specific role of dose levels, since in these patients symptoms occurred mostly at 40 mg/day or higher. We report a case of complex partial status epilepticus in a patient receiving a low dose of tiagabine and review all 11 case reports of nonconvulsive status epilepticus in patients on tiagabine, with regard to daily doses. Our analysis suggests an individual risk threshold of unknown aetiology.
Assuntos
Anticonvulsivantes/efeitos adversos , Epilepsia Parcial Complexa/tratamento farmacológico , Ácidos Nipecóticos/efeitos adversos , Estado Epiléptico/induzido quimicamente , Adulto , Anticonvulsivantes/administração & dosagem , Relação Dose-Resposta a Droga , Quimioterapia Combinada , Eletroencefalografia/efeitos dos fármacos , Potenciais Evocados/efeitos dos fármacos , Humanos , Masculino , Ácidos Nipecóticos/administração & dosagem , Estado Epiléptico/diagnóstico , TiagabinaRESUMO
Patients with primary orthostatic tremor (OT) experience a disabling sense of unsteadiness but rarely fall. In order to study the relationship between the development of subjective unsteadiness, objective unsteadiness and tremor, we recorded standing under four conditions (eyes open or closed, feet together or apart) in six patients with OT. Subjective unsteadiness was indicated by the patients on a four-point scale using a hand-held slider. Objective unsteadiness was assessed by measuring the path lengths of the centre of foot pressure and body motion at the level of the cervical spine. Tremor was measured by surface electromyography from leg and paraspinal muscles. OT patients were objectively more unsteady than controls. Objective unsteadiness also increased disproportionately in patients when standing with eyes closed. These findings suggest that balance control in OT is abnormal and shows increased visual dependence. Subjective unsteadiness increased from mild to severe over seconds to minutes. The increase was faster when standing with eyes closed or feet together. However, although escalating subjective unsteadiness was paralleled by an increase in leg tremor, there were no comparable changes in either paraspinal tremor or objective unsteadiness during the course of a stand. We conclude that there is a dissociation between subjective and objective unsteadiness. This implies that subjective unsteadiness does not arise simply from an awareness of increased body sway. We postulate that the sensation of unsteadiness arises from a tremulous disruption of proprioceptive afferent activity from the legs. This disturbance gives rise to increased co-contracting drive to the leg muscles in order to stiffen the joints and increase stability. Since muscle activity remains tremor-locked, the tremulous proprioceptive feedback is increased, which then further increases the sensation of unsteadiness, and so on in a vicious circle of escalating activity.
Assuntos
Tontura/fisiopatologia , Equilíbrio Postural , Tremor/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Tontura/complicações , Eletromiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Postura , Tremor/complicações , Vertigem/etiologiaRESUMO
Visuomotor rotation (VMR) is a variant of the classic mental rotation paradigm. Subjects perform a center-out arm reaching movement, with the instruction to point clockwise or anticlockwise away from the direction of a reaction signal by a prespecified amount. Like classic mental rotation (MR) tasks, there is a linear relationship between reaction time (RT) and required angle of rotation (angular disparity). Although functional imaging studies have consistently demonstrated parietal activations centered around the intraparietal sulcus during MR tasks, the involvement of parietal cortex in VMR has not been investigated. The aim of the present experiments was to test in human subjects whether VMR also involves activity in parietal areas. We used short trains of transcranial magnetic stimulation (TMS) to produce a temporary "virtual lesion" of the posterior parietal cortex (PPC) around the intraparietal sulcus during the reaction period of a VMR task. Four pulses of 20-Hz rTMS were applied to the left PPC, right PPC, or vertex (control condition) 100 ms after the presentation of an instruction cue. Reaction times (RTs) were evenly prolonged by right or left parietal TMS compared with vertex stimulation, but only for large angles of rotation, and without affecting the spatial accuracy of the final response. A control experiment showed that parietal rTMS did not impair visual perception or the ability to judge the size of visual angles. The data thus provide evidence for bilateral involvement of the PPC in VMR that increases with processing demands.
Assuntos
Atenção/fisiologia , Imaginação/fisiologia , Magnetismo , Orientação/fisiologia , Lobo Parietal/fisiologia , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Adulto , Análise de Variância , Mapeamento Encefálico , Feminino , Humanos , MasculinoRESUMO
Bilateral striopallidodentate calcinosis, also known as Fahr's disease, is characterized by symmetric calcifications of the basal ganglia, thalami, dentate nuclei of the cerebellum and white matter of the cerebral hemispheres. Besides the common idiopathic etiology of bilateral intracerebral calcinosis, alterations of calcium metabolism are present in rare cases, which are especially caused by hormonal dysfunction of the parathyroids. Advanced imaging techniques, such as CT and MRI, demonstrate increasing relevance regarding diagnosis of bilateral striopallidodentate calcinosis. Intracranial calcifications are routinely observed with high sensitivity by CT. On MR images calcifications exhibit different signal intensities, which depend on the stage of the disease, differences in calcium metabolism and the compound of these calcifications. Application of a new high-resolution, susceptibility-weighted MR sequence allows detailed visualization of the intracerebral calcifications in Fahr's disease. Further diagnostic methods and important aspects regarding clinical manifestation of bilateral striopallidodentate calcinosis are also discussed.
Assuntos
Doenças dos Gânglios da Base/diagnóstico , Calcinose/diagnóstico , Imageamento por Ressonância Magnética/métodos , Doenças Neurodegenerativas/diagnóstico , Diagnóstico Diferencial , HumanosRESUMO
The study was performed to compare whole-body short time inversion recovery (STIR) MR imaging and (99m)Tc-methylene diphosphonate planar scintigraphy in the examination of children with suspected multifocal skeletal malignant lesions. Sixteen patients with known or suspected malignant skeletal disease underwent both whole-body STIR MR imaging and bone scintigraphy. The lesions were described and numbered according to scintigraphic evaluation criteria. Thus, 16 regions were analyzed in each patient for the comparison between the two modalities. Histology was proven in the primary malignant regions. Follow-up MRIs were registered. Scintigraphy and MRI follow-up were evaluated as gold standard. A total of 139 different lesions was observed by both modalities. Baseline whole-body MRI revealed 119 bone lesions in 256 possible sites (46.5%); scintigraphy revealed only 58 lesions (22.6%). Congruence was observed in only four patients (25%). According to the location of the lesion, correlation was observed in 39/139 lesions (28%). In all, 57.5% of the lesions were detected only by MRI and 14.5% of the lesions were detected only by scintigraphy. Whole-body MRI was more sensitive (P<0.001). Of all lesions numbered which could be separated in the initial MRI, whole-body MRI detected 178 lesions in the patients. The results suggest that whole-body MRI using a STIR sequence is an effective radiation free method for examination of children with suspected multifocal bone lesions. MRI showed more lesions than conventional (99m)Tc-methylene diphosphonate scintigraphy. Therefore, whole-body MRI may be feasible as a screening modality for metastatic and skip lesions in osteosarcoma, PNET, Ewing sarcoma and Langerhans cell histiocytosis in children.
Assuntos
Neoplasias Ósseas/diagnóstico , Adolescente , Adulto , Neoplasias Ósseas/diagnóstico por imagem , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Imageamento por Ressonância Magnética , Masculino , Compostos Radiofarmacêuticos , Medronato de Tecnécio Tc 99m , Tomografia Computadorizada de EmissãoRESUMO
It is occasionally necessary to repeat diffusion weighted imaging (DWI) after giving intravenous contrast medium (CM). However, the effects of CM on DWI and apparent diffusion coefficients (ADC) have not been fully examined. The aim of this prospective study was to investigate whether there are any diagnostically significant differences between echo-planar imaging (EPI)-DWI before and after intravenous CM. EPI-DWI was acquired twice in 203 consecutive patients before and after i.v. CM. Three blinded readers rated the diagnostic image quality. Quantitative ADC calculations were performed before and after CM in all 72 patients with lesions sufficiently large for quantification, and in 72 normal brain regions. Of the 203 patients, 127 had abnormalities on MRI, including ischaemic stroke (52), bleeding (nine), brain tumour with disturbed blood-brain barrier (BBB) (18) and other lesions (48). There were no significant signal differences on isotropic DWI before and after CM, even in lesions with definite disturbance of the BBB. No statistically significant difference between ADC of lesions and contralateral normal brain was observed.
Assuntos
Isquemia Encefálica/patologia , Neoplasias Encefálicas/patologia , Imagem Ecoplanar , Hemorragias Intracranianas/patologia , Adulto , Idoso , Barreira Hematoencefálica , Meios de Contraste/administração & dosagem , Meios de Contraste/farmacocinética , Feminino , Gadolínio DTPA/administração & dosagem , Gadolínio DTPA/farmacocinética , Humanos , Infusões Intravenosas , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Estudos Prospectivos , Reprodutibilidade dos Testes , Método Simples-CegoRESUMO
OBJECTIVE: To evaluate the reproducibility of imaging and analysis for bone mineral density (BMD) determination using digital computer-assisted X-ray radiogrammetry (DXR; Pronosco X-posure, version V.2, Sectra Pronosco, Denmark); to verify potential factors that influence BMD extrapolation such as tube voltage, film-focus distance (FFD), film quality and brand (Kodak T-MAT-Plus, Konika SRH, Agfa Scopix), imaging technology (conventional, digital), imaging system (Kodak, Agfa) and exposure level (mAs); and to clarify whether DXR analysis based on printouts of digital images is comparable to analysis of conventional images. DESIGN AND PATIENTS: The hand of a cadaver was X-rayed using varied parameters: 4-8 mAs, 40-52 kV, 90-130 cm FFD. Radiographs under standardised conditions were performed 10 times using a conventional machine (Philips Super 80 CP) and the printouts of a digital system (Digital Diagnost Philips Optimus) for the analysis of reproducibility. One image was scanned and analysed 10 times additionally for imaging reproducibility. RESULTS: Reliability error of the system for the imaging process using conventional radiographs-rays was 0.49% (standard conditions: 6 mAs, 40 kV, 1 m FFD), using printouts of digital images was 2.89% (4 mAs, 42 kV, 1 m FFD) and regarding the analysis process was 0.22%. BMD calculation is not affected by alterations in FFD (precision error 1.21%), mAs (0.83%) or film quality/brand (0.38%), but differs significantly depending on tube voltage (2.70%). The system was not able to analyse conventional images with tube voltages of 49/52 kV. CONCLUSION: DXR technology is stable with most of the tested parameters. Normative data should exclusively be used for calculations using similar tube voltage or correction factors. All other parameters had no significant influence on the BMD calculation. Reproducibility is high. For technical reasons it is not recommended to use the printouts of digital images for BMD determination.