• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 18
  • 13
  • 3
  • 1
  • Tagged with
  • 45
  • 45
  • 45
  • 45
  • 14
  • 13
  • 13
  • 13
  • 13
  • 12
  • 10
  • 9
  • 5
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

MRI Contrast Agent Studies of Compartmental Differentiation, Dose-Dependence, and Tumor Characterization in the Brain: A Dissertation

Shazeeb, Mohammed S. 23 November 2010 (has links)
Magnetic resonance imaging (MRI) has increasingly become the preferred imaging modality in modern day research to study disease. MRI presents an imaging technique that is practically non-invasive and without any ionizing radiation. This dissertation presents the use of contrast agents in MRI studies to differentiate compartments, to study dose dependence of relaxation times, and to characterize tumors using signal amplifying enzymes in the brain. Differentiating compartments in the brain can be useful in diffusion studies to detect stroke at an early stage. Diffusion-weighted NMR techniques have established that the apparent diffusion coefficient (ADC) of cerebral tissue water decreases during ischemia. However, it is unclear whether the ADC change occurs due to changes in the intracellular (IC) space, extracellular (EC) space, or both. To better understand the mechanism of water ADC changes in response to ischemic injury, making IC and EC compartment specific measurements of water diffusion is essential. The first study was done where manganese (Mn2+) was used as an IC contrast agent. Mn2+ uptake by cells causes shortening of the T1 relaxation time of IC water. The relative difference in T1 relaxation times between the IC and EC compartments can be used to discriminate between the MR signals arising from water in the respective compartments. Mn2+ is also widely used in manganese-enhanced MRI (MEMRI) studies to visualize functional neural tracts and anatomy in the brain in vivo. In animal studies, the goal is to use a dose of Mn2+ that will maximize the contrast while minimizing its toxic effects. The goal of dose study was to investigate the MRI dose response of Mn2+ in rat brain following SC administration of Mn2+. The dose dependence and temporal dynamics of Mn2+ after SC injection can prove useful for longitudinal in vivo studies that require brain enhancement to persist for a long period of time to visualize neuroarchitecture like in neurodegenerative disease studies. Contrast agents, in addition to their use in compartmental differentiation and dose studies, can be used for imaging tumors. The last study in this dissertation focuses on imaging EGF receptors in brain tumors. We tested a novel pretargeting imaging approach that includes the administration of humanized monoclonal antibody (anti-EGFR mAb, EMD72000) linked to enzymes with complementing activities that use a low-molecular weight paramagnetic molecule (diTyr-GdDTPA) as a reducing substrate administered following the mAb conjugates. We analyzed the differential MR tumor signal decay in vivo using orthotopic models of human glioma. The patterns of MR signal change following substrate administration revealed differences in elimination patterns that allowed distinguishing between non-specific and specific modes of MR signal decay.
22

Supervised Learning for White Matter Bundle Segmentation

Bertò, Giulia 03 June 2020 (has links)
Accurate delineation of anatomical structures in the white matter of the human brain is of paramount importance for multiple applications, such as neurosurgical planning, characterization of neurological disorders, and connectomic studies. Diffusion Magnetic Resonance Imaging (dMRI) techniques can provide, in-vivo, a mathematical representation of thousands of fibers composing such anatomical structures, in the form of 3D polylines called streamlines. Given this representation, a task of invaluable interest is known as white matter bundle segmentation, whose aim is to virtually group together streamlines sharing a similar pathway into anatomically meaningful structures, called white matter bundles. Obtaining a good and reliable bundle segmentation is however not trivial, mainly because of the intrinsic complexity of the data. Most of the current methods for bundle segmentation require extensive neuroanatomical knowledge, are time consuming, or are not able to adapt to different data settings. To overcome these limitations, the main goal of this thesis is to develop a new automatic method for accurate white matter bundle segmentation, by exploiting, combining and extending multiple up-to-date supervised learning techniques. The main contribution of the project is the development of a novel streamline-based bundle segmentation method based on binary linear classification, which simultaneously combines information from atlases, bundle geometries, and connectivity patterns. We prove that the proposed method reaches unprecedented quality of segmentation, and that is robust to a multitude of diverse settings, such as when there are differences in bundle size, tracking algorithm, and/or quality of dMRI data. In addition, we show that some of the state-of-the-art bundle segmentation methods are deeply affected by a geometrical property of the shape of the bundles to be segmented, their fractal dimension. Important factors involved in the task of streamline classification are: (i) the need for an effective streamline distance function and (ii) the definition of a proper feature space. To this end, we compare some of the most common streamline distance functions available in the literature and we provide some guidelines on their practical use for the task of supervised bundle segmentation. Moreover, we investigate the possibility to include, in a streamline-based segmentation method, additional information to the typically employed streamline distance measure. Specifically, we provide evidence that considering additional anatomical information regarding the cortical terminations of the streamlines and their proximity to specific Regions of Interest (ROIs) helps to improve the results of bundle segmentation. Lastly, significant attention is paid to reproducibility in neuroscience. Following the FAIR (Findable, Accessible, Interoperable and Reusable) Data Principles, we have integrated our pipelines of analysis into an online open platform devoted to promoting reproducibility of scientific results and to facilitating knowledge discovery.
23

Avaliação de substância branca através de imagem por tensor de difusão em crianças  em risco e portadoras de transtorno bipolar / Evaluation of white matter using diffusion tensor imaging in children at-risk and with bipolar disorder

Teixeira, Ana Maria Aristimunho 21 September 2012 (has links)
O Transtorno de Humor Bipolar (THB) acomete até 3% dos adultos e os filhos desses pacientes constituem uma população em risco para o desenvolvimento de transtornos psiquiátricos. No entanto, faltam marcadores que permitam a identificação precoce dos indivíduos que apresentam maior vulnerabilidade para o desenvolvimento de psicopatologia. Estudos preliminares com Ressonância Magnética (RM) indicaram que alterações em substância branca estariam presentes não apenas em pacientes em episódio de alteração de humor, mas também em pacientes eutímicos e em seus familiares saudáveis, sugerindo que tais alterações poderiam constituir um endofenótipo potencial deste transtorno. A Imagem por Tensor de Difusão (Diffusion Tensor Magnetic Resonance Imaging - DT-MRI) é uma aquisição de RM que permite análise mais completa e detalhada das características da substância branca cerebral que a RM tradicional. A investigação de alterações na estrutura cerebral, particularmente de substância branca, de jovens portadores de THB não medicados e familiares saudáveis criteriosamente avaliados pode ajudar a elucidar a neurobiologia subjacente ao THB e, conseqüentemente, a identificar marcadores de vulnerabilidade ao transtorno. Objetivo: Avaliar se havia alterações em substância branca em crianças e adolescentes com THB e crianças e adolescentes filhos saudáveis de portadores de transtorno do humor bipolar quando comparados a controles saudáveis, utilizando a técnica de neuroimagem de DTMRI. Nossas hipóteses eram que jovens com THB e filhos de pacientes com THB, quando comparados a controles saudáveis, apresentariam (i) diminuição da fração de anisotropia (FA) e (ii) essas alterações seriam mais pronunciadas em crianças acometidas por THB do que em crianças saudáveis filhas de pacientes com THB. Métodos: Obtivemos imagens de DT-MRI de boa qualidade de 16 crianças e adolescentes com THB (média de idade ± D.P.= 12,7 ± 2,5 anos), 15 filhos saudáveis de pacientes com THB tipo I (média de idade ± D.P.= 13,5 ± 2,7 anos) e 15 controles saudáveis (média de idade ± D.P.= 13,5 ± 2,5 anos). Os diagnósticos foram formulados de acordo com os critérios do DSM-IV, usando as entrevistas Kiddie-SADS-PL (crianças) e Structured Clinical Interview for DSM-IV (adultos). A RM foi realizada em um scanner Philips 3,0 Tesla, com os seguintes parâmetros de aquisição: TR = 6106,0 ms, TE = 65,0ms, FOV = 224x224mm, espessura de corte = 2.0mm, sem gap, matriz de aquisição = 112x112 pixels e 3 médias, resultando em tamanho de voxel isotrópico = 2,0x2,0x2,0mm. As imagens de DTI foram pré-processadas com programas oriundos do FMRIB\'s software library (FSL), de acordo com o pipeline sugerido para o processamento de substância branca com Tract-Based Spatial Statistics (TBSS) e análise estatística com o programa Randomise (ambos integrantes do FSL). Resultados: Os grupos não diferiram em idade, gênero, grau de puberdade ou QI. Valores de FA de pacientes pediátricos com THB foram significativamente menores em relação aos de controles saudáveis (p < 0,05, corrigido para múltiplas comparações) em um cluster de 695 voxels no hemisfério direito que abrange a porção superiora da corona radiata e o corpo do corpo. Não houve diferença significativa entre pacientes com THB e filhos saudáveis de pacientes com THB, ou com filhos saudáveis de pacientes com THB e controles saudáveis. Discussão: Nossos dados corroboram a literatura de diminuição de FA em crianças e adolescentes com THB e avançam em mostrar esta alteração em pacientes não medicados. Mas nossos resultados não apoiam a hipótese de alterações em substância branca como endofenótipo de THB. Estudos de seguimento com amostras maiores e rigorosamente caracterizadas são necessários para se elucidar o papel das alterações em substância branca no THB. / Up to 3% of adults are affected with Bipolar Disorder (BD) and the offspring of these patients constitute a population at risk for the development of psychiatric disorders. Nevertheless, there are still no vulnerability markers to allow the early identification of those who are at greater risk of developing psychopathology among this population. Preliminary data indicate that white matter abnormalities may precede the disease onset and be present even in unaffected relatives - suggesting they could be further explored as an endophenotype for BD. Diffusion Tensor Magnetic Resonance Imaging (DTMRI) is an MRI acquisition that allows a thorough and detailed analysis of brain white matter characteristics. The investigation of white matter alterations in young, nonmedicated, BD patients and healthy relatives may help us understand the underlying neurobiology of BD. Objectives: evaluate white matter alterations in children at-risk and with BD using DT-MRI. Our hypothesis were that BD offspring, compared to healthy controls, would exhibit (i) reduced fractional anisotropy (FA) and (ii) these alterations would be more pronounced in children with BD than in those at-risk. Methods: We successfully scanned 16 BD patients (mean age ± S.D.= 12,7 ± 2,5 years) 15 healthy offspring with at least one parent with BD I diagnosis (mean age ± S.D.= 13,5 ± 2,7 years) and 15 healthy controls (mean age ± S.D.= 13,5 ± 2,5 years) with no history of psychiatric disorder in first-degree relatives. Psychiatric diagnosis were established according to the DSM-IV criteria, using the Kiddie-SADS-PL interview (children) and Structured Clinical Interview for DSM-IV (adults). The MRI was conducted at a 3.0 Tesla Philips scanner. Acquisition: the parameters were TR = 6106,0ms, TE = 65,0ms, FOV= 224x224mm, slice thickness = 2.0mm/no gap, matrix acquisition = 112x112 pixels, 3 averages, resulting in an isotropic voxel = 2,0x2,0x2,0 mm. DT-MRI images were preprocessed according to do FMRIB\'s software library\'s (FSL) pipeline for Tract-Based Spatial Statistics\' (TBSS) and Randomise analyses. Results: Groups did not differ in age, gender or pubertal status. Voxelwise analyses showed significant differences in FA values between BD patients and healthy controls (p < 0,05, FDR corrected for multiple comparisons) in a 695 voxels cluster comprising right corona radiata and corpus callosum . Discussion: This study was the first to evaluate a sample of non-medicated BD children and adolescents with DT-MRI and it corroborates extant literature data of lower FA in BD children compared to healthy controls. Nevertheless, our data do not support white matter alterations as an endophenotype for BD. More studies, with larger and well characterized samples are necessary to advance our understanding of the role of white matter alteration in BD.
24

Avaliação por ressonância magnética funcional da necrose coagulativa por ablação de radiofrequência nas metástases hepáticas colorretais / Functional magnetic resonance evaluation of coagulative necrosis radiofrequency ablation of colorectal liver metastases

Lia Roque Assumpção 16 July 2012 (has links)
A maioria dos pacientes que apresentam metástases hepáticas colorretais (MHCR) não são elegíveis para ressecção. Por isso, outras técnicas para se alcançar o controle locorregional da doença têm sido utilizadas. A Ablação por Radiofrequência (ARF) hepática tem sido empregada frequentemente para o tratamento desta condição devido às boas taxas de resposta, principalmente quando associada ao emprego de quimioterápicos modernos. Apesar da caracterização das MHCR no pré-operatório estar bem estabelecida, os parâmetros de ressonância magnética (RM) após ARF no período pós-cirúrgico requerem maior padronização objetiva. O coeficiente de difusão aparente de água (CDA) tem sido usado na RM como um parâmetro de isquemia e necrose. Entretanto, não está ainda bem definido seu papel e das imagens ponderadas de difusão (DWI) na avaliação da necrose coagulativa gerada pela ARF, especificamente em pacientes com MHCR. O objetivo deste estudo consiste em avaliar o espectro de mudança em RM funcional após a ARF de MHCR. Foi realizado estudo retrospectivo entre 2001 e 2006, avaliando 51 pacientes que foram submetidos à ARF por MHCR no Hospital Johns Hopkins (Baltimore, EUA) dos quais 16 preencheram os critérios de inclusão. Os critérios de inclusão foram: (1) apresentar MHCR tratada cirurgicamente com intenção curativa por ARF guiados por ultrassom per-operatório, e (2) ter uma RM anterior e imediatamente após a cirurgia (até 10 dias). As imagens de RMs antes e após a ablação hepática para MCHR foram identificadas e revistas. As imagens de RM de difusão e captação de contraste foram feitas numa unidade de 1.5 T. Imagens em T2 e T1 foram realizadas na presença e ausência de contraste venoso. Todos os exames tiveram a espessura de 4 a 6 mm e um intervalo de 2 mm, apresentando um angulo de rotação de 150. O índice de difusão foi determinado com um b-valor (intensidade do gradiente de difusão) de 500 seg/mm2. As análises de parâmetros para avaliar e comparar o pré e pós ARF através da RM funcional incluiram: (1) valores do mapa de CDA, (2) captação de contraste, (3) difusão e (4) mudança no tamanho da lesão. Em adição, a sobrevida mediana global e tempo para recorrência local foram calculados. As imagens foram avaliadas por um consenso de dois radiologistas/cirurgiões. Foram avaliados no total 65 lesões, com tamanho médio pré-ablação de 1,7 cm. Após ablação o tamanho médio da lesão aumentou para 3,5 cm (p<0,001). A captação de contraste nas fases arterial e venosa diminuíram significativamente após ARF (diminuição média 10% e 17,5%, respectivamente, p = 0,002 e <0,001). O valor médio do mapa de CDA da lesão foi de 2.79 x 10-3 mm2/seg pré-ARF, e após ARF diminui em média para 1.75 x 10-3 mm2/seg (p<0.001). A sobrevida mediana global foi de 34,7 meses. A ressonância magnética funcional através da captação de contraste e difusão pode prover uma estimativa subjetiva e objetiva da necrose coagulativa tissular e da desidratação celular na área ablada por radiofrequência. Quando combinada ao aumento no tamanho do tumor, podem atuar como um marcador adicional de resposta tumoral. / The majority of patients who have colorectal liver metastases (CLM) are not eligible for resection. Therefore other techniques to achieve locoregional control of the disease have been used. Liver radiofrequency ablation (RFA) have been more frequently used for treatment of this condition due to good response rates, particularly when associated to modern chemotherapy. Although characterization of CLM pre ablation are well established, parameters post RFA require more objective standardization. Apparent water diffusion coefficient (ADC) have been used as a necrosis and ischemic parameters in MR analyzes. Even though it is not yet well defined its rule and the diffusion weighted images (DWI) in evaluation of RFA generated coagulative necrosis, specifically in patients with CLM. The objective of this study is to analyze the spectrum of changes in functional MR after CLM RFA. A retrospective study was done between 2001 and 2006, where 51 patients were submitted to CLM RFA in Johns Hopkins Hospital (Baltimore, USA) and 16 fulfilled inclusion criteria. The inclusion criteria were: (1) to have CLM treated with curative intention on surgery guided by intra-operative ultra-sound (IOUS), and (2) to have an MR immediately and after (until 10 days) the RFA procedure. MR images before and after RFA were identified and reviewed. Contrasted and DWI MR Images were done in 1.5 T unit. T1 and T2 images were done with and without venous contrast. All of exams had 4 to 6 mm thickness, 2mm gap and a flip angle of 150. ADC was determined with a b-value of 500 sec/mm2 (intensity of diffusion gradient). Pre and post RFA functional MR analyzes included the following parameters: (1) ADC value, (2) contrast enhancement, (3) diffusion and (4) change in tumor size. In addition, survival and time to local recurrence were calculated. The images were reviewed by two radiologist/surgeon consensus. A total of 65 lesions were evaluated, with 1,7cm mean size pre RFA. After RFA the mean size increased to 3,5 cm(p<0,001). Arterial and venous contrast enhancement diminished significantly post RFA (lowered to mean 10% and 17,5%, respectively, p = 0,002 and p<0,001). Mean ADC lesion pre RFA was 2.79 x 10-3 mm2/sec, and pré-ARF, after RFA lowered to mean 1.75 x 10-3 mm2/sec (p<0.001). Median overall survival was 34,7 months. Functional MR through diffusion and contrast enhancement can provide coagulative necrosis and cellular dehydration subjective and objective estimation in the ablated area. When associated with increase in tumor size can act as an additional marker of tumor response.
25

Diffusion-weighted magnetic resonance imaging with readout-segmented echo-planar imaging

Frost, Stephen Robert January 2012 (has links)
Diffusion-weighted (DW) magnetic resonance imaging is an important neuroimaging technique that has successful applications in diagnosis of ischemic stroke and methods based on diffusion tensor imaging (DTI). Tensor measures have been used for detecting changes in tissue microstructure and for non-invasively tracing white matter connections in vivo. The most common image acquistion strategy is to use a DW single-shot echo-planar imaging (ss-EPI) pulse sequence, which is attractive due to its robustness to motion artefacts and high imaging speed. However, this sequence has limited achievable spatial resolution and suffers from geometric distortion and blurring artefacts. Readout-segmented echo-planar imaging (rs-EPI) is a DW sequence that is capable of acquiring high-resolution images by segmenting the acquisition of k- space into multiple shots. The fast, short readouts reduce distortion and blurring and the problem of artefacts due to motion-induced phase changes between shots can be overcome with navigator techniques. The rs-EPI sequence has two main shortcomings. (i) The method is slow to produce image volumes, which is limiting for clinical scans due to patient welfare and prevents us from acquiring very many directions in DTI. (ii) The sequence (like other diffusion techniques) is far from the optimum repetition time (TR) for acquiring data with the highest possible signal-to-noise ratio (SNR) in a given time. The work in this thesis seeks to address both of these important issues using a range of approaches. In Chapter 4 a partial Fourier extension is presented, which addresses point (i) by reducing the number of readout segments acquired and estimating the missing data. This allows reductions in scan time by approximately 40&percnt; and the reliability of the images is demonstrated in comparisons with the original images. The application of a simultaneous multi-slice scheme to rs-EPI, to address points (i) and (ii), is described in Chapter 5. Using the slice-accelerated rs-EPI sequence, tractography data were compared to ss-EPI data and high-resolution trace-weighted data were acquired in clinically relevant scan times. Finally, a 3D multi-slab extension that addresses point (i) is presented in Chapter 6. A 3D sequence could also allow higher resolution in the slice direction than 2D multi-slice methods, which are limited by the difficulties in exciting thin, accurate slices. A 3D version of rs-EPI was simulated and implemented and a k-space acquisition synchronised to the cardiac cycle showed substantial improvements in image artefacts compared to a conventional k-space acquisition.
26

Avaliação por ressonância magnética funcional da necrose coagulativa por ablação de radiofrequência nas metástases hepáticas colorretais / Functional magnetic resonance evaluation of coagulative necrosis radiofrequency ablation of colorectal liver metastases

Lia Roque Assumpção 16 July 2012 (has links)
A maioria dos pacientes que apresentam metástases hepáticas colorretais (MHCR) não são elegíveis para ressecção. Por isso, outras técnicas para se alcançar o controle locorregional da doença têm sido utilizadas. A Ablação por Radiofrequência (ARF) hepática tem sido empregada frequentemente para o tratamento desta condição devido às boas taxas de resposta, principalmente quando associada ao emprego de quimioterápicos modernos. Apesar da caracterização das MHCR no pré-operatório estar bem estabelecida, os parâmetros de ressonância magnética (RM) após ARF no período pós-cirúrgico requerem maior padronização objetiva. O coeficiente de difusão aparente de água (CDA) tem sido usado na RM como um parâmetro de isquemia e necrose. Entretanto, não está ainda bem definido seu papel e das imagens ponderadas de difusão (DWI) na avaliação da necrose coagulativa gerada pela ARF, especificamente em pacientes com MHCR. O objetivo deste estudo consiste em avaliar o espectro de mudança em RM funcional após a ARF de MHCR. Foi realizado estudo retrospectivo entre 2001 e 2006, avaliando 51 pacientes que foram submetidos à ARF por MHCR no Hospital Johns Hopkins (Baltimore, EUA) dos quais 16 preencheram os critérios de inclusão. Os critérios de inclusão foram: (1) apresentar MHCR tratada cirurgicamente com intenção curativa por ARF guiados por ultrassom per-operatório, e (2) ter uma RM anterior e imediatamente após a cirurgia (até 10 dias). As imagens de RMs antes e após a ablação hepática para MCHR foram identificadas e revistas. As imagens de RM de difusão e captação de contraste foram feitas numa unidade de 1.5 T. Imagens em T2 e T1 foram realizadas na presença e ausência de contraste venoso. Todos os exames tiveram a espessura de 4 a 6 mm e um intervalo de 2 mm, apresentando um angulo de rotação de 150. O índice de difusão foi determinado com um b-valor (intensidade do gradiente de difusão) de 500 seg/mm2. As análises de parâmetros para avaliar e comparar o pré e pós ARF através da RM funcional incluiram: (1) valores do mapa de CDA, (2) captação de contraste, (3) difusão e (4) mudança no tamanho da lesão. Em adição, a sobrevida mediana global e tempo para recorrência local foram calculados. As imagens foram avaliadas por um consenso de dois radiologistas/cirurgiões. Foram avaliados no total 65 lesões, com tamanho médio pré-ablação de 1,7 cm. Após ablação o tamanho médio da lesão aumentou para 3,5 cm (p<0,001). A captação de contraste nas fases arterial e venosa diminuíram significativamente após ARF (diminuição média 10% e 17,5%, respectivamente, p = 0,002 e <0,001). O valor médio do mapa de CDA da lesão foi de 2.79 x 10-3 mm2/seg pré-ARF, e após ARF diminui em média para 1.75 x 10-3 mm2/seg (p<0.001). A sobrevida mediana global foi de 34,7 meses. A ressonância magnética funcional através da captação de contraste e difusão pode prover uma estimativa subjetiva e objetiva da necrose coagulativa tissular e da desidratação celular na área ablada por radiofrequência. Quando combinada ao aumento no tamanho do tumor, podem atuar como um marcador adicional de resposta tumoral. / The majority of patients who have colorectal liver metastases (CLM) are not eligible for resection. Therefore other techniques to achieve locoregional control of the disease have been used. Liver radiofrequency ablation (RFA) have been more frequently used for treatment of this condition due to good response rates, particularly when associated to modern chemotherapy. Although characterization of CLM pre ablation are well established, parameters post RFA require more objective standardization. Apparent water diffusion coefficient (ADC) have been used as a necrosis and ischemic parameters in MR analyzes. Even though it is not yet well defined its rule and the diffusion weighted images (DWI) in evaluation of RFA generated coagulative necrosis, specifically in patients with CLM. The objective of this study is to analyze the spectrum of changes in functional MR after CLM RFA. A retrospective study was done between 2001 and 2006, where 51 patients were submitted to CLM RFA in Johns Hopkins Hospital (Baltimore, USA) and 16 fulfilled inclusion criteria. The inclusion criteria were: (1) to have CLM treated with curative intention on surgery guided by intra-operative ultra-sound (IOUS), and (2) to have an MR immediately and after (until 10 days) the RFA procedure. MR images before and after RFA were identified and reviewed. Contrasted and DWI MR Images were done in 1.5 T unit. T1 and T2 images were done with and without venous contrast. All of exams had 4 to 6 mm thickness, 2mm gap and a flip angle of 150. ADC was determined with a b-value of 500 sec/mm2 (intensity of diffusion gradient). Pre and post RFA functional MR analyzes included the following parameters: (1) ADC value, (2) contrast enhancement, (3) diffusion and (4) change in tumor size. In addition, survival and time to local recurrence were calculated. The images were reviewed by two radiologist/surgeon consensus. A total of 65 lesions were evaluated, with 1,7cm mean size pre RFA. After RFA the mean size increased to 3,5 cm(p<0,001). Arterial and venous contrast enhancement diminished significantly post RFA (lowered to mean 10% and 17,5%, respectively, p = 0,002 and p<0,001). Mean ADC lesion pre RFA was 2.79 x 10-3 mm2/sec, and pré-ARF, after RFA lowered to mean 1.75 x 10-3 mm2/sec (p<0.001). Median overall survival was 34,7 months. Functional MR through diffusion and contrast enhancement can provide coagulative necrosis and cellular dehydration subjective and objective estimation in the ablated area. When associated with increase in tumor size can act as an additional marker of tumor response.
27

Avaliação de substância branca através de imagem por tensor de difusão em crianças  em risco e portadoras de transtorno bipolar / Evaluation of white matter using diffusion tensor imaging in children at-risk and with bipolar disorder

Ana Maria Aristimunho Teixeira 21 September 2012 (has links)
O Transtorno de Humor Bipolar (THB) acomete até 3% dos adultos e os filhos desses pacientes constituem uma população em risco para o desenvolvimento de transtornos psiquiátricos. No entanto, faltam marcadores que permitam a identificação precoce dos indivíduos que apresentam maior vulnerabilidade para o desenvolvimento de psicopatologia. Estudos preliminares com Ressonância Magnética (RM) indicaram que alterações em substância branca estariam presentes não apenas em pacientes em episódio de alteração de humor, mas também em pacientes eutímicos e em seus familiares saudáveis, sugerindo que tais alterações poderiam constituir um endofenótipo potencial deste transtorno. A Imagem por Tensor de Difusão (Diffusion Tensor Magnetic Resonance Imaging - DT-MRI) é uma aquisição de RM que permite análise mais completa e detalhada das características da substância branca cerebral que a RM tradicional. A investigação de alterações na estrutura cerebral, particularmente de substância branca, de jovens portadores de THB não medicados e familiares saudáveis criteriosamente avaliados pode ajudar a elucidar a neurobiologia subjacente ao THB e, conseqüentemente, a identificar marcadores de vulnerabilidade ao transtorno. Objetivo: Avaliar se havia alterações em substância branca em crianças e adolescentes com THB e crianças e adolescentes filhos saudáveis de portadores de transtorno do humor bipolar quando comparados a controles saudáveis, utilizando a técnica de neuroimagem de DTMRI. Nossas hipóteses eram que jovens com THB e filhos de pacientes com THB, quando comparados a controles saudáveis, apresentariam (i) diminuição da fração de anisotropia (FA) e (ii) essas alterações seriam mais pronunciadas em crianças acometidas por THB do que em crianças saudáveis filhas de pacientes com THB. Métodos: Obtivemos imagens de DT-MRI de boa qualidade de 16 crianças e adolescentes com THB (média de idade ± D.P.= 12,7 ± 2,5 anos), 15 filhos saudáveis de pacientes com THB tipo I (média de idade ± D.P.= 13,5 ± 2,7 anos) e 15 controles saudáveis (média de idade ± D.P.= 13,5 ± 2,5 anos). Os diagnósticos foram formulados de acordo com os critérios do DSM-IV, usando as entrevistas Kiddie-SADS-PL (crianças) e Structured Clinical Interview for DSM-IV (adultos). A RM foi realizada em um scanner Philips 3,0 Tesla, com os seguintes parâmetros de aquisição: TR = 6106,0 ms, TE = 65,0ms, FOV = 224x224mm, espessura de corte = 2.0mm, sem gap, matriz de aquisição = 112x112 pixels e 3 médias, resultando em tamanho de voxel isotrópico = 2,0x2,0x2,0mm. As imagens de DTI foram pré-processadas com programas oriundos do FMRIB\'s software library (FSL), de acordo com o pipeline sugerido para o processamento de substância branca com Tract-Based Spatial Statistics (TBSS) e análise estatística com o programa Randomise (ambos integrantes do FSL). Resultados: Os grupos não diferiram em idade, gênero, grau de puberdade ou QI. Valores de FA de pacientes pediátricos com THB foram significativamente menores em relação aos de controles saudáveis (p < 0,05, corrigido para múltiplas comparações) em um cluster de 695 voxels no hemisfério direito que abrange a porção superiora da corona radiata e o corpo do corpo. Não houve diferença significativa entre pacientes com THB e filhos saudáveis de pacientes com THB, ou com filhos saudáveis de pacientes com THB e controles saudáveis. Discussão: Nossos dados corroboram a literatura de diminuição de FA em crianças e adolescentes com THB e avançam em mostrar esta alteração em pacientes não medicados. Mas nossos resultados não apoiam a hipótese de alterações em substância branca como endofenótipo de THB. Estudos de seguimento com amostras maiores e rigorosamente caracterizadas são necessários para se elucidar o papel das alterações em substância branca no THB. / Up to 3% of adults are affected with Bipolar Disorder (BD) and the offspring of these patients constitute a population at risk for the development of psychiatric disorders. Nevertheless, there are still no vulnerability markers to allow the early identification of those who are at greater risk of developing psychopathology among this population. Preliminary data indicate that white matter abnormalities may precede the disease onset and be present even in unaffected relatives - suggesting they could be further explored as an endophenotype for BD. Diffusion Tensor Magnetic Resonance Imaging (DTMRI) is an MRI acquisition that allows a thorough and detailed analysis of brain white matter characteristics. The investigation of white matter alterations in young, nonmedicated, BD patients and healthy relatives may help us understand the underlying neurobiology of BD. Objectives: evaluate white matter alterations in children at-risk and with BD using DT-MRI. Our hypothesis were that BD offspring, compared to healthy controls, would exhibit (i) reduced fractional anisotropy (FA) and (ii) these alterations would be more pronounced in children with BD than in those at-risk. Methods: We successfully scanned 16 BD patients (mean age ± S.D.= 12,7 ± 2,5 years) 15 healthy offspring with at least one parent with BD I diagnosis (mean age ± S.D.= 13,5 ± 2,7 years) and 15 healthy controls (mean age ± S.D.= 13,5 ± 2,5 years) with no history of psychiatric disorder in first-degree relatives. Psychiatric diagnosis were established according to the DSM-IV criteria, using the Kiddie-SADS-PL interview (children) and Structured Clinical Interview for DSM-IV (adults). The MRI was conducted at a 3.0 Tesla Philips scanner. Acquisition: the parameters were TR = 6106,0ms, TE = 65,0ms, FOV= 224x224mm, slice thickness = 2.0mm/no gap, matrix acquisition = 112x112 pixels, 3 averages, resulting in an isotropic voxel = 2,0x2,0x2,0 mm. DT-MRI images were preprocessed according to do FMRIB\'s software library\'s (FSL) pipeline for Tract-Based Spatial Statistics\' (TBSS) and Randomise analyses. Results: Groups did not differ in age, gender or pubertal status. Voxelwise analyses showed significant differences in FA values between BD patients and healthy controls (p < 0,05, FDR corrected for multiple comparisons) in a 695 voxels cluster comprising right corona radiata and corpus callosum . Discussion: This study was the first to evaluate a sample of non-medicated BD children and adolescents with DT-MRI and it corroborates extant literature data of lower FA in BD children compared to healthy controls. Nevertheless, our data do not support white matter alterations as an endophenotype for BD. More studies, with larger and well characterized samples are necessary to advance our understanding of the role of white matter alteration in BD.
28

Perinatal brain damage in very preterm infants:prenatal inflammation and neurologic outcome in children born term and preterm

Kaukola, T. (Tuula) 11 October 2005 (has links)
Abstract Despite improvements in peri- and neonatal care and an increase in the overall survival of very preterm infants, the incidence of neurologic sequelae has remained high. The pathogenesis of many brain imaging findings, such as white matter damage, WMD, is poorly understood. The factors predisposing to brain damage differ between term and preterm infants. More detailed information is needed of how brain imaging correlates with neurodevelopmental impairment after the neonatal period. The present study investigated the pre- and perinatal factors leading to brain damage and their effects on neurologic and neurodevelopmental outcome in very preterm children. We also analyzed the differences in umbilical cord serum cytokines in term and preterm children with cerebral palsy, CP. Furthermore, the correlations between the findings on diffusion-weighted imaging, DWI, measurements in brainstem auditory evoked potentials, and neurodevelopmental outcome were assessed. We demonstrated that pregnancies complicated by combined histologic chorioamnionitis and placental insufficiency independently predicted abnormal neurologic outcome at 2 years of corrected age. WMD additively predicted poor outcome. Isolated fetal inflammatory response, umbilical cord serum acute phase cytokines (IL-1α, IL-1β, IL-6, IL-8, TNF-α), did not associate with neurologic outcome in either term or preterm children. Instead, a cluster of cytokines different from acute phase cytokines were related to CP, and the protein profile differed between term and preterm children. Disturbed hemodynamics during the pre- and perinatal period affected outcome in very preterm infants. In severe placental insufficiency, fetal cardiac compromise associated with suboptimal neurodevelopmental outcome at 1 year of corrected age. In addition, several clinical factors characterising cardiorespiratory status after birth associated with abnormal neurologic outcome at 2 years of corrected age. We found the apparent diffusion coefficient, ADC, a quantitative measurement of water diffusion, in pons to correlate with the conduction rate of impulses travelling through the auditory tract. We also demonstrated a high value of ADC in corona radiata to associate with poor outcome in gross motor and eye-hand coordination skills at 2 years of corrected age. Both pre- and perinatal factors associate with later outcome in very preterm infants. An isolated fetal inflammatory response does not predict neurologic outcome. Findings on DWI in specific brain regions predict abnormal neurodevelopmental outcome. / Tiivistelmä Huolimatta vastasyntyneisyyskauden parantuneista hoitotuloksista ja että yhä useampi hyvin ennenaikaisena syntynyt lapsi jää eloon, heidän neurologisen vammautuneisuuden ilmaantuvuus on edelleen korkea. Monien aivojen kuvantamislöydösten, kuten valkean aineen vaurion, syntymekanismit tunnetaan huonosti. Aivojen vaurioitumiselle altistavat tekijät eroavat täysiaikaisena ja ennenaikaisena syntyneillä lapsilla. Tarvitaan myös aiempaa yksityiskohtaisempaa tietoa aivojen kuvantamislöydösten merkityksestä lasten vastasyntyneisyyskauden jälkeiseen kehitykseen. Tässä tutkimuksessa selvitettiin raskauden- ja syntymänaikaisia tekijöitä, jotka vaikuttavat aivojen vaurioitumiseen hyvin ennenaikaisena syntyneillä lapsilla sekä näiden tekijöiden merkitystä lasten neurologiseen kehitykseen. Tarkastelimme myös napaveren seerumin välittäjäaineiden, sytokiinien, eroavuuksia täysiaikaisena ja ennenaikaisena syntyneillä CP-lapsilla. Lisäksi selvitimme diffuusiomagneettitutkimus- ja aivorunkoherätevastelöydösten sekä neurologisen kehityksen välisiä yhteyksiä. Tämän tutkimuksen mukaan kohdunsisäinen tulehdus ja istukan vajaatoiminta yhtä aikaa esiintyessään ovat poikkeavan neurologisen kehityksen itsenäisiä riskitekijöitä lapsilla 2 vuoden korjatussa iässä tutkittuna. Valkoisen aivoaineen vaurio edelleen lisäsi näiden lasten huonon neurologisen kehityksen ennustetta. Raskauden kestosta riippumatta, sikiön tulehdusvastetta kuvaavat napaveren akuutin vaiheen tulehdusvälittäjäaineet (IL-1α, IL-1β, IL-6, IL-8, TNF- α) eivät vaikuttaneet lapsen neurologiseen kehitykseen. Sen sijaan, CP-lasten napaverestä löytyi erityinen joukko ei-akuutin vaiheen välittäjäaineita. Nämä valkuaisaineet erosivat toisistaan täysiaikaisena ja ennenaikaisena syntyneillä CP-lapsilla. Raskauden- ja syntymänaikaiset verenkierron häiriöt vaikuttivat hyvin ennenaikaisena syntyneiden lasten myöhempään kehitykseen. Vaikeassa istukan vajaatoiminassa sikiön sydämen toiminnan heikkeneminen liittyi lapsen suboptimaaliin neurologiseen kehitykseen 1 vuoden korjatussa iässä tutkittuna. Lisäksi useat syntymänjälkeiset keuhkojen ja verenkierron tilaa kuvaavat kliiniset tekijät liittyivät lapsen poikkeavaan neurologiseen kehitykseen 2 vuoden korjatussa iässä tutkittuna. Tutkimuksemme mukaan, veden diffuusiota määrällisesti kuvaava diffuusiokerroin, ADC, aivosillasta mitattuna, liittyi impulssien johtumisnopeutueen kuuloradastossa. Lisäksi korkea ADC-arvo aivojen sepelviuhkassa liittyi karkean motoriikan ja silmä-käsi-yhteistyötaitojen huonoon kehitykseen 2 vuoden korjatussa iässä tutkittuna. Sekä raskauden- että syntymänaikaiset tekijät vaikuttavat hyvin ennenaikaisena syntyneiden lasten myöhempään kehitykseen. Yksittäinen sikiön tulehdusvaste ei ennakoi lapsen neurologista kehitystä. Tiettyjen aivoalueiden diffuusiokuvantamislöydökset ennustavat lapsen poikkeavaa neurologista kehitystä.
29

Magnetnorezonantna sekvenca difuzionog kretanja u proceni metastatske invazije limfnih čvorova kod malignih tumora ženskih polnih organa / Diffusion-weighted magnetic resonance imaging for evaluation of malignant lymph node invasion in patients with female genital neoplasms

Basta Nikolić Marijana 15 September 2016 (has links)
<p>UVOD: Maligni tumori reproduktivnih organa nalaze se među vodećim uzrocima obolevanja i umiranja od malignih bolesti žena, kako u svetu, tako i u Srbiji. Jedan od najvažnijih puteva &scaron;irenja ovih bolesti je limfogeni, a konvencionalna radiolo&scaron;ka dijagnostika limfnih čvorova kod ovih pacijentkinja je neprecizna. Funkcionalna radiolo&scaron;ka dijagnostika, uključujući i magnentno rezonantnu sekvencu difuzionog kretanja (DWI) i iz nje izvedenu ADC mapu koja omogućava kvantitativnu analizu difuzionih osobina unutar limfnog čvora, daju obećavajuće rezultate u mogućnosti razlikovanja benignih od maligno izmenjenih limfnih čvorova male karlice i ingvinuma kod pacijentkinja obolelih od malignih tumora ženskih polnih organa. CILJ: Cilj studije je 1. utvrđivanje dijagnostičkih mogućnosti magnetnorezonantne sekvence difuzionog kretanja (DWI) u razlikovanju benignih od maligno izmenjenih limfnih čvorova male karlice i ingvinuma kod pacijentkinja obolelih od malignih tumora ženskih polnih organa, poređenjem preoperativno načinjenog magnetnorezonantnog pregleda i postoperativnog patohistolo&scaron;kog nalaza; 2. analiza povezanosti osobina metastatski izmenjenih limfnih čvorova na sekvenci difuzionog kretanja (DWI) i gradusa primarnog tumora, i 3. utvrđivanje uticaja tehničkih karakteristika sekvenci difuzinonog kretanja (DWI) na magnetnorezonantu procenu metastatske infiltracije karličnih i ingvinalnih limfnih čvorova i postoperativnog patohistolo&scaron;kog nalaza. MATERIJAL I METODE: Istraživanje je sprovedeno u periodu od 2013. do 2016.godine, kao prospektivna klinička studija u Centru za radiologiju, na Operativnom odeljenju Zavoda za ginekologiju, Klinike za ginekologiju i aku&scaron;erstvo i u Zavodu za patologiju Kliničkog Centra Vojvodine u Novom Sadu. Studija je obuhvatila 80 pacijentkinja obolelih od malignih tumora vulve, vagine, grlića materice, tela materice i jajnika. Na osnovu lokalizacije malignog tumora sve ispitanice su razvrstane u 5 grupa: grupa A- 3 žene obolele od carcinoma vulve, grupa B- 1 žena obolela od karcinoma vagine, grupa C-32 pacijentkinje obolele od karcinoma grlića materice, grupa D- 30 pacijentkinja obolelih od malignih tumora tela materice i grupa E- 14 žena obolelih od malignih tumora jajnika. Procena stadijuma bolesti definitivno je izvr&scaron;ena posle operacije na osnovu histopatolo&scaron;kog pregleda kompletnog hirur&scaron;kog materijala uključujući i pregled uklonjenih limfnih čvorova na osnovu aktuelne FIGO klasifikacije stadijuma bolesti zasebno za svaku pojedinačnu lokalizaciju malignog tumora. Svim pacijentkinjama je preoperativno načinjen magnetnorezonantni pregled male karlice na uređaju za magnetnu rezonancu 1.5 T General Electric Signa HDx u Centru za radiologiju, Kliničkog centra Vojvodine. Kod istih pacijentkinja naknadno je sprovedeno standardno hirur&scaron;ko lečenje po protokolu hirur&scaron;kog lečenja za dato maligno ginekolo&scaron;ko oboljenje sa karličnom i/ili ingvinalnom limfadenektomijom. Postoperativno je izvr&scaron;ena patohistolo&scaron;ka analiza hirur&scaron;ki uklonjenog materijala i limfnih čvorova razdvojenih po anatomskim grupama u karlici i ingvinalnoj regiji. REZULTATI: Ukupno 2320 limfnih čvorova je mapirano i patohistolo&scaron;ki pregledano kod 80 pacijenata. Metastaze u limfnim čvorovima patohistolo&scaron;ki su verifikovane kod 28 pacijenata (35%). Kod ovih 28 (35%) pacijentkinja, 152 (27,28%) od ukupno 557 limfnih čvorova bilo je metastatski izmenjeno na patohistolo&scaron;kom pregledu. Metastaze u limfnim čvorovima utvrđene su kod 2 pacijentkinje (7,14%) sa karcinomom vulve, 11 (39,28%) sa karcinomom cerviksa, 9 (32,14%) sa tumorima tela materice, te 6 (21,42%) sa tumorima jajnika. Od 28 pacijentkinja kod kojih su utvrđeni pozitivni limfni čvorovi, 14 pacijentkinja (50%) imalo je dobro diferentovan primarni tumor, 8 (28,57%) srednje diferentovan, dok je 6 (21,42%) imalo lo&scaron;e diferentovan primarni tumor. Od ukupno 152 metastatski izmenjena limfna čvora u na&scaron;oj studiji, 8 limfnih čvorova (5,26%) pripadalo je ingvinalnoj grupi od čega 5 (3,289%) povr&scaron;noj ingvinalnoj, a 3 ( 1,97%) dubokoj ingvinalnoj grupi, 8 (5,26%) parametrijalnoj grupi, 48 (31,58%) opturatornoj grupi, 40 (26,31%) spolja&scaron;njoj ilijačnoj grupi, 36 (23,684%) unutra&scaron;njoj ilijačnoj grupi, dok je 12 (7,89%) pripadalo zajedničkoj ilijačnoj grupi karličnih limfnih čvorova. Kraći prečnik limfnog čvora nije pokazao značajnu razliku između metastatskih ( mean &plusmn; SD, 8,3 &plusmn; 5.4 mm, raspon , 4.5-30 mm ) i limfnih čvorova koji nisu bili metastatski izmenjeni ( 6,3 mm &plusmn; 1,5 , 4,5-9,6 mm ; P= 0,191 ). Izmerena ADC vrednost bila je značajno niža kod metastatski izmenjenih limfnih čvorova (mean &plusmn; SD , ADC: 0,8725 x 10-3 mm2/s &plusmn; 0,0125) nego kod limfnih čvorova koji nisu bili metastatski izmenjeni (mean &plusmn; SD, ADC: 1,116 x 10- 3 mm2/s &plusmn; 0,1848; P=0,001). Prosečne vrednosti ADC kod b =800 s/mm2 i b =1200 s/mm2 nisu se značajno razlikovale između metastaski izmenjenih limfnih čvorova (mean &plusmn; SD, ADC: 0,8575 &plusmn; 0,0125 x 10-3 mm2/s, ADC:0,8859 &plusmn; 0,0125 x 10-3 mm2/s) i limfnih čvorova koji nisu metastatski izmenjeni (mean &plusmn; SD, ADC:1,0345 &plusmn; 0,1222 x 10-3 mm2/s, ADC:1,1125 &plusmn; 1638 x 10-3 mm2/s; P =0,657 i P = 0,877). Ako se koristi vrednost ADC od 0,860 x 10- 3 mm2 / s kao kritična vrednost za razlikovanje metastatskih od limfnih čvorova koji nisu metastatski izmenjeni, senzitivnost DWI MR iznosila je 89%, specifičnost 85% i ukupna tačnost 86%. Pozitivna prediktivna vrednost (PPV) DWI MR u detekciji limfnih metastaza u karličnoj i ingvinalnoj regiji iznosila je 30%. Negativna prediktivna vrednost (NPV) testa iznosila je 99%. Pozitivna prediktivna vrednost (PPV) MR zasnovana na kriterijumu ADC vrednosti značajno je veća u odnosu na sve kriterijuma veličine (P &lt; 0,001). Negativna prediktivna vrednost MR zasnovanoj na kriterijumima veličine limfnog čvora i na ACD vrednosti nisu se međusobno statistički značajno razlikovali (P&lt;0,05). Performanse dijagnostičke metode (MR) bile su značajno bolje za minimalnu ADC vrednost od svih kriterijuma baziranih na veličini limfnih čvorova ( P=0.001 za minimalnu ADC vrednost u odnosu na sve druge kriterijume). MRI na osnovu definisanog modela koji kombinuje kriterijum ADC vrednosti sa kriterijumom veličine ima sledeće dijagnostičke performanse za diferencijaciju malignih od benignih limfnih čvorova: senzitivnost od 95%, specifičnost 92%, sveukupna tačnost od 92,5%, pozitivnu prediktivnu vrednost od 46% i negativnu prediktivnu vrednost od 99.6%. ZAKLJUČAK: Kriterijum veličine limfnog čvora nije dovoljno precizan pokazatelj metastatske invazije limfnih čvorova. Sekvenca difuzionog kretanja (DWI) uvek se mora analizirati zajedno sa ADC mapom i visoko rezolutivnim T1 i T2 otežanim magnetnorezonantnim sekvencama. Studijom je dokazan visok stepen povezanosti između preoperativnog određivanja metastaske infiltracije karličnih i ingvinalnih limfnih čvorova malignih tumora ženskih polnih organa primenom sekvence difuzionog kretanja (DWI) i postoperativnog patohistolo&scaron;kog nalaza. Uz graničnu ADC vrednost od 0,860 x 10-3 mm2/ s, senzitivnost MRI DWI u otkrivanju metastatskih limfnih čvorova iznosi 89%, a specifičnost 85%. Kombinacija ADC vrednosti i morfolo&scaron;kih karakteristika limfnih čvorova konvencionalnim magnentno rezonantnim pregledom je najprecizniji prediktor postojanja metastatske infiltracije karličnih i ingvinalnih limfnih čvorova kod pacijentkinja sa malignim tumorima ženskih polnih organa. Tehničke karakteristike sekvenci difuzionog kretanja (DWI) u smislu razlike u visokim b vrednostima ne utiču na magnentno rezonantnu procenu metastatske infiltracije karličnih i ingvinalnih limfnih čvorova kod pacijentkinja sa malignim tumorima ženskih polnih organa. Studijom nije utvrđena statistički značajna razlika između preoperativno utvrđenih ADC vrednosti metastatski izmenjenih limfnih čvorova i stepena histolo&scaron;ke diferencijacije ovih tumora. Sekvenca difuzionog kretanja (DWI) je brza, jednostavna, neinvazivna metoda koja značajno doprinosi dijagnostičkim mogućnostima magnetne rezonance u razlikovanju benignih od malignih limfnih čvorova male karlice i ingvinuma.</p> / <p>INTRODUCTION: Malignant tumors of reproductive organs are among the leading causes of morbidity and mortality in women, both in Serbia and worldwide. Lymphatic spread is one of the most important pathways of tumor dissemination. However, conventional lymph node imaging in these patients is imprecise. Functional imaging, including diffusion-weighted magnetic resonance imaging (DWI MRI) and derived ADC map which allows quantitative analysis of diffusion parameters within a lymph node, provide promising results in discrimination benign from malignant pelvic and inguinal lymph nodes in patients with gynecological malignancies. AIM: Aim of the study was: 1. To assess diagnostic performances of DWI MRI in differentiation between benign and malignant pelvic and inguinal lymph nodes in patients with gynecological malignancies, by comparison of preoperative magnetic resonance and postoperative histopathological findings. 2. To analyze correlation between DWI characteristics of metastatic lymph nodes and grade of the primary tumor, and 3. To evaluate the influence of technical characteristics of DWI sequences on MR assessment of metastatic pelvic and inguinal lymph node and postoperative histopathological findings. MATERIAL and METHODS: The prospective clinical study was conducted in Center for Radiology, Surgery Department of Clinic for Gynecology and Obstetrics and Pathology Department of Clinical Center of Vojvodina from 2013 to 2016. It comprised 80 patients with malignant tumors of vulva, vagina, uterine cervix and body and ovaries. Based on the localization of the tumor, all patients were divided into 5 groups: group A-3 patients with vulvar cancer, group B- 1 patient with vaginal cancer, group C- 32 patients with cervical cancer, group D- 30 patients with uterine body tumors and group E- 14 patients with malignant ovarian tumors. Staging of the disease was performed after surgery based on histopathological examination of complete surgical specimen, including examination of removed lymph nodes, based on current FIGO classification separately for each primary tumor location. Preoperatively, all patients underwent MRI examination (1.5 T General Electric Signa HDx) at Center for Radiology, Clinical Center of Vojvodina. The same patients underwent standard surgical treatment according to the treatment protocol regarding the tumor type and stage, with complete pelvic and/or inguinal lymphadenectomy. Histopathological examination of surgically removed material and lymph nodes separated in pelvic and inguinal anatomic groups was performed after the surgery. RESULTS: The total of 2320 of lymph nodes were mapped and histopathologically examined in 80 patients included in the study. Metastases in lymph nodes were histopathologically confirmed in 28 patients (35%). In these 28(35%) patients, in 152 (27,28%) out of 557 lymph nodes histopathological examination confirmed metastases. Lymph node metastases were confirmed in 2 patients (7.14%) with vulvar cancer, 11 (39.28%) with cervical cancer, 9 (32.14%) with uterine body tumors and 6 (21.42%)patients with ovarian tumors. In 28 patients with positive lymph nodes, 14 patients (50%) had well differentiated primary tumor, 8 (28.57%) moderately differentiated, while 6 (21.42%) patients had poorly differentiated primary tumor. Out of 152 metastatic lymph nodes in our study, 8 lymph nodes (5.26%) were inguinal ( 5 (3.289%) superficial inguinal and 3 ( 1.97%) deep inguinal group), 8 (5.26%) were parametrial, 48 (31. 58%) obturatory, 40 (26.31%) external iliac, 36 (23.684%) internal iliac, while 12 (7. 89%) belonged to common iliac pelvic lymph nodes group. Shorter lymph node axis did not show significant difference between metastatic ( mean &plusmn; SD, 8.3 &plusmn; 5.4 mm, range , 4.5-30 mm ) and benign lymph nodes ( 6.3 mm &plusmn; 1.5 , 4.5-9.6 mm ; P= 0.191 ). Measured ADC values were significantly lower in metastatic (mean &plusmn; SD , ADC: 0.8725 x 10-3 mm2/s &plusmn; 0.0125) than benign lymph nodes (mean &plusmn; SD, ADC: 1.116 x 10-3 mm2/s &plusmn; 0.1848; P=0.001). Mean ADC values at b =800 s/mm2 and b =1200 s/mm2 did not differ significantly between metastatic (mean &plusmn; SD, ADC: 0.8575 &plusmn; 0.0125 x 10-3 mm2/s, ADC:0.8859 &plusmn; 0,0125 x 10-3 mm2/s) and benign lymph nodes (mean &plusmn; SD, ADC:1.0345 &plusmn; 0.1222 x 10-3 mm2/s, ADC:1.1125 &plusmn; 1638 x 10-3 mm2/s; P =0.657 i P = 0.877). If ADC value of 0.860 x 10- 3 mm2 / s is determined as a cut off value for discrimination of benign and malignant lymph nodes, DWI MRI sensitivity was 89%, specificity 85% and overall accuracy was 86%. Positive predictive value (PPV) of DWI MR in detection of pelvic and inguinal lymph node metastases was 30%. Negative predictive value (NPV) of the test was 99%. MRI PPV based on ADC value criteria was significantly higher compared to all size-based criteria (P &lt; 0,001). MRI NPV based on size based and ADC values criteria did not differ significantly (P&lt;0,05). Performances of diagnostic method (MRI) were significantly better for minimal ADC value compared to all lymph node size-based criteria ( P=0.001 for minimal ADC value compared to all other criteria). Combination of ADC value criteria and size-based criteria yields MRI the following diagnostic performances in discrimination between benign and malignant lymph nodes: sensitivity 95%, specificity 92%, overall accuracy 92.5%, positive predictive value 46% and negative predictive value 99.6%. CONCLUSION: Lymph node size is not sufficiently precise criteria for determination of metastatic lymph node involvement. DWI sequence always needs to be evaluated together with ADC map and high resolution T1W and T2W magnetic resonance sequences. The study shows high correlation between preoperative assessment of pelvic and inguinal lymph node metastases from gynecological malignancies using MRI DWI and postoperative histopathological findings. With a cut off ADC value of 0.860 x 10-3 mm2/ s, sensitivity of MRI DWI in metastatic lymph node detection is 89%, while specificity is 85%. Combination of ADC values and morphological lymph nodes characteristics assessed by conventional MRI is the most precise predictor of metastatic pelvic and inguinal lymph node invasion in patients with gynecological malignancies. Technical characteristics of DWI i.e. different high b-values do not influence MR assessment of metastatic pelvic and inguinal lymph node involvement in patients with gynecological malignancies. The study did not confirm statistically significant difference between preoperatively measured ADC valued of metastatic lymph nodes and histological grade of primary tumors. DWI MRI sequence is fast, simple, noninvasive method which aids significantly to MRI diagnostic performances in discrimination between benign and malignant pelvic and inguinal lymph nodes.</p>
30

Funkcionalni magnetno rezonantni imidžing u dijagnostici dijabetesne nefropatije kod bolesnika sa tipom 2 dijabetes melitusa / Functional magnetic resonance imaging in the diagnosis of diabetic nephropathy in patients with type 2 diabetes mellitus

Mrđanin Tijana 06 June 2019 (has links)
<p>Uvod: Dijabetes melitus (DM) je oboljenje koje poprima karakteristike globalne epidemije. Sve ţe&scaron;&scaron;e oboljevaju pacijenti mlaŤeg ţivotnog doba. Simptomi DM tip 2 su blagi, ţesto neprimetni, te se oboljenje otkriva kada se ve&scaron; manifestuju komplikacije. Dijabetesna nefropatija (DN) je jedna od mnogobrojnih komplikacija dijabetes melitusa tip 2, koja se zavr&scaron;ava terminalnom bubreţnom insuficijencijom. DN se ţesto neblagovremeno dijagnostikuje, zbog ţega se kasno zapoţinje leţenje. Rano otkrivanje DN od kljuţnog je znaţaja, jer omogu&scaron;ava primenu terapijskih postupaka usmerenih na oţuvanje preostalih zdravih nefrona i prevenciju terminalne bubreţne slabosti. Cilj: Prikazati poreme&scaron;aj difuzije molekula vode unutar bubrega kod DN, kori&scaron;&scaron;enjem mapa prividnog koeficijenta difuzije, kvantifikacijom vrednosti prividnog koeficijenta difuzije (ADC) i frakcione anizotropije (FA). Materijal i metode: U prospektivnu studiju bilo je ukljuţeno 10 zdravih dobrovoljaca i 91 pacijent oboleo od DM tip 2. Pacijenti oboleli od DM tip 2 podeljeni su u ţetiri grupe na osnovu vrednosti procenjene jaţine glomerularne filtracije (JGF) (grupe: I JGF &ge; 90, II 89-60, III 59-30, IV &le; 29 ml/min/1,73m&sup2;). Svim ispitanicima uraŤen je MR pregled bubrega, uz primenu DWI (b=0 i b=400 s/mm&sup2;) i DTI (b=1000 s/mm&sup2;) sekvence, na aparatu jaţine 1.5T. ADC i FA vrednosti raţunate su u &scaron;est regija od interasa, po tri u korteksu i meduli svakog bubrega. Dobijene vrednosti komparirane su sa laboratorijskim parametrima bubreţne funkcije (urea, kreatinin, mokra&scaron;na kiselina) i procenjenom JGF. Rezultati: Ne postoje statistiţki znaţajne razlike ADC i FA vrednosti parenhima, korteksa i medule levog i desnog bubrega kod zdravih dobrovoljaca i DM pacijenata. Kod DM pacijenata ADC je ve&scaron;a u korteksu nego u meduli (p=0,00), a FA vrednost je ve&scaron;a u meduli nego u korteksu (p=0,284). Urea, kreatinin i cistatin C imaju negativnu korelaciju sa ADC korteksa, medule i parenhima (p&lt;0,05), a JGF ima pozitivnu korelaciju sa ADC korteksa, medule i parenhima, kao i sa FA medule (p&lt;0,05) kod DM pacijenata. Na osnovu Post hoc testa za ADC, kod DM pacijenata postoje razlike izmeŤu I i IV grupe, izmeŤu II i IV grupe i III i IV grupe (p&le;0,05). IzmeŤu godina ţivota, teţine, BMI, JGF, HbA1c, uree i &Scaron;UK-a, postoji razlika DM pacijenata i zdravih dobrovoljaca (p&lt;0,05). Niţa je vrednost FA medule DM pacijenata u odnosu na zdrave dobrovoljce (p&lt;0,05). Postoji razlika ADC korteksa, medule i parenhima izmeŤu zdravih dobrovoljaca i DM pacijenata IV grupe, kao izmeŤu DM pacijenata I i II grupe u odnosu na IV grupu. TakoŤe postoji razlika izmeŤu FA medule zdravih dobrovoljaca i DM pacijenata I i IV grupe (p&lt;0,05). Regresiona analiza pokazala je uticaj kreatinina na ADC desnog bubrega i ADC oba bubrega, dok procenjena JGF i cistatin C imaju uticaj na ADC desnog i levog bubrega, ADC oba bubrega i FA levog bubrega (p&lt;0,05). Traktografija je prikazala naru&scaron;enu arhitektoniku kod pacijenata sa o&scaron;te&scaron;enom bubreţnom funkcijom. Zakljuţak: Postoji korelacija laboratorijskih parametara bubreţne funkcije i procenjene JGF sa ADC i FA vrednostima bubrega, &scaron;to ukazuje na ulogu funkcionalnog magnetno rezonantnog imidţinga u dijagnostici dijabetesne nefropatije. Neophodna su dalja istraţivanja koja &scaron;e doprineti standardizaciji MR protokola i potvrdi znaţaja MR biomarkera u dijagnostici DN. Na osnovu na&scaron;ih rezultata vrednost FA medule osetljiviji je parametar od ADC vrednosti u otkrivanju ranog o&scaron;te&scaron;enja bubrega u sklopu dijabetes melitusa.</p> / <p>Introduction: Diabetes mellitus (DM) is a disease that takes on the characteristics of a global epidemic. Patients of younger age are more and more commonly affected. Symptoms of type 2 DM are mild, often imperceptible, and therefore the disease is usually detected when complications are already manifested. Diabetic nephropathy (DN) is one of the many complications of type 2 diabetes mellitus that leads to terminal renal failure. Diagnosis of DN is often late, causing the delay of the treatmen. Early detection of DN is crucial because it allows the application of therapeutic procedures aimed at preserving the remaining healthy nephrons and preventing terminal renal failure. Objective: To investigate a diffusion of water molecule within a kidney in DN using apparent diffusion coefficient maps, by quantification of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values in diabetic patients with DM type 2. Material and methods: The prospective study comprised 10 healthy volunteers and 91 DM type 2 patients. DM patients were divided into four groups based on the values of the estimated glomerular filtration (eGFR) (groups: I eGFR &ge; 90, II 89-60, III 59-30, IV &le; 29 ml/min/1.73m&sup2;). All subjects were scanned by 1.5T MR using DWI (b=0 and b=400 s/mm&sup2;) and DTI (b=1000 s/mm&sup2;) sequences. ADC and FA values were calculated in six regions of interest, three in cortex and three in medulla of each kidney. Obtaned values were compared to laboratory parameters of renal function (urea, creatinine, uric acid) and eGFR. Results: There were no statistically significant differences between ADC and FA values of parenchyma, cortex and medulla of the left and the right kidney in healthy volunteers and DM patients. In DM patients, the ADC value was higher in the cortex than in the medulla (p=0.00) and the FA value was higher in the medulla than in the cortex (p=0.284). The negative correlation was found between urea, creatinine and cystatin C with ADC cortex, medulla and parenchyma (p&lt;0.05), and the eGFR was positively correlated with ADC cortex, medulla and parenchyma, and with FA medulla (p&lt;0.05) in DM patients. Based on the Post hoc test for ADC, in DM patients there were differences between I and IV group, between II and IV group, III and IV group (p&le;0,05). Regarding age, weight, BMI, GFR, HbA1c, urea, and glucose in the serum, there was a difference between DM patients and healthy volunteers (p&lt;0.05). The FA of medulla in DM patients was lower than of healthy volunteers (p&lt;0.05). There were differences in ADC of cortex, medulla, and parenchyma between healthy volunteers and DM patients of IV group, as well as between DM patients of I and II group compared to IV group. There were differences of medulla FA values between healthy volunteers and group I, accompanied by healthy and IV group of DM patients (p&lt;0.05). Regression analysis showed the influence of creatinine on ADC of right kidney and ADC of both kidneys, while eGFR and cystatin C have an effect on ADC of right and left kidney, ADC of both kidneys and FA of left kidney (p&lt;0.05). The tractography showed the disturbed architectonics in patients with impaired renal function. Conclusion: There is correlation of laboratory parameters of renal function and eGFR with ADC and FA values of the kidney, indicating the role of functional magnetic resonance imaging in the diagnosis of DN. Further research that will contribute to standardizing the MR protocol and confirming the importance of MRI biomarker in the diagnosis of DN are needed. Based on our results, the values of medulla FA is more sensitive parameter than the ADC value in detecting early kidney damage in the context of diabetes mellitus.</p>

Page generated in 0.1764 seconds