RESUMO
Three-dimensional (3D) turbo-spin echo (TSE) sequences have outgrown the stage of mere sequence optimization and by now are clinically applicable. Image blurring and acquisition times have been reduced, and contrast for T1-, T2-, and moderately T2-weighted (or intermediate-weighted) fat-suppressed variants has been optimized. Data on sound-to-noise ratio efficiency and contrast are available for moderately T2-weighted fat-saturated sequence protocols. The 3-T MRI scanners help to better exploit isotropic spatial resolution and multiplanar reformatting. Imaging times range from 5 to 10 minutes, and they are shorter than the cumulative acquisition times of three separate orthogonal two-dimensional (2D) sequences. Recent suggestions go beyond secondary reformations by using online 3D rendering for image evaluation. Comparative clinical studies indicate that the diagnostic performance of 3D TSE for imaging of internal derangements of joints is at least comparable with conventional 2D TSE with potential advantages of 3D TSE for small highly curved structures. But such studies, especially those with direct arthroscopic correlation, are still sparse. Whether 3D TSE will succeed in entering clinical routine imaging on a broader scale will depend on further published clinical evidence, on further reduction of imaging time, and on improvement of its integration into daily practice.
Assuntos
Interpretação de Imagem Assistida por Computador , Imageamento Tridimensional , Imageamento por Ressonância Magnética , Doenças Musculoesqueléticas/patologia , HumanosRESUMO
OBJECTIVE: In most half-Fourier imaging methods, explicit phase replacement is used. In combination with parallel imaging, or compressed sensing, half-Fourier reconstruction is usually performed in a separate step. The purpose of this paper is to report that integration of half-Fourier reconstruction into iterative reconstruction minimizes reconstruction errors. MATERIALS AND METHODS: The L1-norm phase constraint for half-Fourier imaging proposed in this work is compared with the L2-norm variant of the same algorithm, with several typical half-Fourier reconstruction methods. Half-Fourier imaging with the proposed phase constraint can be seamlessly combined with parallel imaging and compressed sensing to achieve high acceleration factors. RESULTS: In simulations and in in-vivo experiments half-Fourier imaging with the proposed L1-norm phase constraint enables superior performance both reconstruction of image details and with regard to robustness against phase estimation errors. CONCLUSION: The performance and feasibility of half-Fourier imaging with the proposed L1-norm phase constraint is reported. Its seamless combination with parallel imaging and compressed sensing enables use of greater acceleration in 3D MR imaging.
Assuntos
Encéfalo/anatomia & histologia , Compressão de Dados/métodos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Algoritmos , Análise de Fourier , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Processamento de Sinais Assistido por ComputadorRESUMO
OBJECT: We aimed to demonstrate that follow-up scans in longitudinal examinations can be significantly accelerated by using images from previous scans as priors for constrained reconstruction. MATERIALS AND METHODS: In this work, we propose a method for incorporating a prior image to improve the reconstruction of a new acquisition with considerable k-space undersampling, which contains a two-level registration scheme with non-parametric transformation, an adaptive synthesis procedure, and a constrained reconstruction with weighted total variation constraint. The performance of the method is evaluated using simulations, as well as results from volunteer and patient examinations. RESULTS: In vivo experiments with both volunteers and patients show that incorporating a prior image into the constrained reconstruction produces many fewer reconstruction errors compared to the conventional reconstruction using only the highly undersampled k-space data. CONCLUSION: The redundant information in the prior image can be efficiently adopted to improve the reconstruction quality of the new acquisition. When maintaining the image quality, higher acceleration can be achieved with the incorporation of the prior image.
Assuntos
Algoritmos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Reconhecimento Automatizado de Padrão/métodos , Técnica de Subtração , Humanos , Aumento da Imagem/métodos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
OBJECTIVE: 3D TSE imaging is very prone to motion artifacts, especially from uncooperative patients, because of the long scan duration. The need to repeat this time-consuming 3D acquisition in the event of large motion artifacts substantially reduces patient comfort and increases the workload of the scanner. MATERIALS AND METHODS: A new sampling strategy enables homogenized collection of k-space data for 3D TSE imaging. It is combined with Frobenius norm-based motion-detection to enable freely stopped acquisition in 3D TSE imaging whenever excessive subject motion is detected. RESULTS: The feasibility and reliability of the proposed method were demonstrated and evaluated in in-vivo experiments. CONCLUSION: It is shown that the additional overhead related to repeat scanning of the 3D TSE sequence as a result of patient motion can be substantially reduced by using the homogenized k-space sampling strategy with automatic scan completion as determined by Frobenius norm-based motion-detection.
Assuntos
Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Movimento , Artefatos , Estudos de Viabilidade , Humanos , Reprodutibilidade dos TestesRESUMO
OBJECTIVES: To investigate the relation between anatomic changes of the synovium, the bone, the bone marrow and the cartilage to biochemical properties of the cartilage in patients with rheumatoid arthritis (RA). METHODS: 33 patients with RA received 3-T MRI scans of the metacarpophalangeal joints. Two independent methods, (A) the delayed gadolinium enhanced MRI of the cartilage (dGEMRIC, T2-mapping), which was used to assess the biochemical properties of the cartilage; (B) synovitis, osteitis and bone erosions were quantified according to the RA MRI scoring (RAMRIS) method and cartilage thickness (CT), interbone joint space (IBJS, distance between proximal and distal bone surface) and intercartilage joint space (ICJS, distance between proximal and distal cartilage surface) were measured. RESULTS: Biochemical changes of the cartilage, corresponding to low dGEMRIC and high T2 values, were more likely to be seen in joints with decreased IBJS and ICJS as well as decreased CT. For instance, dGEMRIC was directly correlated to the IBJS (p=0.001) and ICJS (p=0.001), whereas T2 mapping was inversely correlated to IBJS and ICJS (both p=0.017). Moreover, the degree of osteitis, and to some extent synovitis, was correlated to biochemical cartilage changes as measured by dGEMRIC (p=0.003) or the T2 mapping (p=0.013). By contrast, bone erosions did not correlate to the degree of biochemical cartilage changes. DISCUSSION: These data support the concept that synovitis and osteitis may be two main triggers for cartilage damage. Thus, the actual inflammatory state of a joint, but not so much the degree of bone erosion, appears to influence cartilage properties in RA.
Assuntos
Artrite Reumatoide/metabolismo , Cartilagem Articular/metabolismo , Articulação Metacarpofalângica/metabolismo , Osteíte/metabolismo , Proteoglicanas/metabolismo , Sinovite/metabolismo , Adulto , Artrite Reumatoide/patologia , Reabsorção Óssea , Cartilagem Articular/patologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Articulação Metacarpofalângica/patologia , Pessoa de Meia-Idade , Osteíte/patologia , Membrana Sinovial/metabolismo , Membrana Sinovial/patologia , Sinovite/patologiaRESUMO
PURPOSE: To quantitatively compare the diagnostic capability of double inversion-recovery (DIR) with F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for detection of seizure focus laterality in temporal lobe epilepsy (TLE). METHODS: This study was approved by the institutional review board, and written informed consent was obtained. Fifteen patients with TLE and 38 healthy volunteers were enrolled. All magnetic resonance (MR) images were acquired using a 3T-MRI system. Voxel-based analysis (VBA) was conducted for FDG-PET images and white matter segments of DIR images (DIR-WM) focused on the whole temporal lobe (TL) and the anterior part of the temporal lobe (ATL). Distribution of hypometabolic areas on FDG-PET and increased signal intensity areas on DIR-WM were evaluated, and their laterality was compared with clinically determined seizure focus laterality. Correct diagnostic rates of laterality were evaluated, and agreement between DIR-WM and FDG-PET was assessed using κ statistics. KEY FINDINGS: Increased signal intensity areas on DIR-WM were located at the vicinity of the hypometabolic areas on FDG-PET, especially in the ATL. Correct diagnostic rates of seizure focus laterality for DIR-WM (0.80 and 0.67 for the TL and the ATL, respectively) were slightly higher than those for FDG-PET (0.67 and 0.60 for the TL and the ATL, respectively). Agreement of laterality between DIR-WM and FDG-PET was substantial for the TL and almost perfect for the ATL (κ = 0.67 and 0.86, respectively). SIGNIFICANCE: High agreement in localization between DIR-WM and FDG-PET and nearly equivalent detectability of them show us an additional role of MRI in TLE.
Assuntos
Epilepsia do Lobo Temporal/diagnóstico , Imageamento por Ressonância Magnética/métodos , Tomografia por Emissão de Pósitrons/métodos , Adolescente , Adulto , Idoso , Encéfalo/patologia , Estudos de Casos e Controles , Criança , Pré-Escolar , Epilepsia do Lobo Temporal/patologia , Epilepsia do Lobo Temporal/fisiopatologia , Feminino , Fluordesoxiglucose F18 , Lateralidade Funcional/fisiologia , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Neuroimagem/métodos , Lobo Temporal/patologia , Lobo Temporal/fisiopatologia , Adulto JovemRESUMO
Fluid attenuated inversion recovery (FLAIR) MRI sequences have become an indispensible tool for defining the malignant boundary in patients with brain tumors by nulling the signal contribution from cerebrospinal fluid allowing both regions of edema and regions of non-enhancing, infiltrating tumor to become hyperintense on resulting images. In the current study we examined the utility of a three-dimensional double inversion recovery (DIR) sequence that additionally nulls the MR signal associated with white matter, implemented either pre-contrast or post-contrast, in order to determine whether this sequence allows for better differentiation between tumor and normal brain tissue. T1- and T2-weighted, FLAIR, dynamic susceptibility contrast (DSC)-MRI estimates of cerebral blood volume (rCBV), contrast-enhanced T1-weighted images (T1+C), and DIR data (pre- or post-contrast) were acquired in 22 patients with glioblastoma. Contrast-to-noise (CNR) and tumor volumes were compared between DIR and FLAIR sequences. Line profiles across regions of tumor were generated to evaluate similarities between image contrasts. Additionally, voxel-wise associations between DIR and other sequences were examined. Results suggested post-contrast DIR images were hyperintense (bright) in regions spatially similar those having FLAIR hyperintensity and hypointense (dark) in regions with contrast-enhancement or elevated rCBV due to the high sensitivity of 3D turbo spin echo sequences to susceptibility differences between different tissues. DIR tumor volumes were statistically smaller than tumor volumes as defined by FLAIR (Paired t test, P = 0.0084), averaging a difference of approximately 14 mL or 24 %. DIR images had approximately 1.5× higher lesion CNR compared with FLAIR images (Paired t test, P = 0.0048). Line profiles across tumor regions and scatter plots of voxel-wise coherence between different contrasts confirmed a positive correlation between DIR and FLAIR signal intensity and a negative correlation between DIR and both post-contrast T1-weighted image signal intensity and rCBV. Additional discrepancies between FLAIR and DIR abnormal regions were also observed, together suggesting DIR may provide additional information beyond that of FLAIR.
Assuntos
Neoplasias Encefálicas/patologia , Meios de Contraste , Glioblastoma/patologia , Imageamento Tridimensional , Imageamento por Ressonância Magnética , Recidiva Local de Neoplasia/patologia , Progressão da Doença , Humanos , Aumento da Imagem , Processamento de Imagem Assistida por Computador , PrognósticoRESUMO
OBJECTIVES: To investigate the diagnostic capability of anterior temporal lobe white matter abnormal signal (ATLAS) for determining seizure focus laterality in temporal lobe epilepsy (TLE) by comparing different MR sequences. METHODS: This prospective study was approved by the institutional review board and written informed consent was obtained. Three 3D sequences (double inversion recovery (DIR), fluid-attenuated inversion recovery (FLAIR) and T2-weighted imaging (T2WI)) and two 2D sequences (FLAIR and T2WI) were acquired at 3 T. Signal changes in the anterior temporal white matter of 21 normal volunteers were evaluated. ATLAS laterality was evaluated in 21 TLE patients. Agreement of independent evaluations by two neuroradiologists was assessed using κ statistics. Differences in concordance between ATLAS laterality and clinically defined seizure focus laterality were analysed using McNemar's test with multiple comparisons. RESULTS: Pre-amygdala high signals (PAHS) were detected in all volunteers only on 3D-DIR. Inter-evaluator agreement was moderate to almost perfect for each sequence. Correct diagnosis of seizure laterality was significantly more frequent on 3D-DIR than on any other sequences (P ≤ 0.031 for each evaluator). CONCLUSIONS: The most sensitive sequence for detecting ATLAS laterality was 3D-DIR. ATLAS laterality on 3D-DIR can be a good indicator for determining seizure focus localization in TLE.
Assuntos
Epilepsia do Lobo Temporal/patologia , Imageamento por Ressonância Magnética/métodos , Fibras Nervosas Mielinizadas/patologia , Adolescente , Adulto , Idoso , Tonsila do Cerebelo/patologia , Criança , Pré-Escolar , Eletroencefalografia , Feminino , Humanos , Imageamento Tridimensional , Lactente , Magnetoencefalografia , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons , Estudos Prospectivos , Convulsões/patologia , Sensibilidade e Especificidade , Lobo Temporal/patologiaRESUMO
Dystrophic epidermolysis bullosa (DEB) is a severe skin fragility disorder associated with trauma-induced blistering, progressive soft tissue scarring, and increased risk of skin cancer. DEB is caused by mutations in type VII collagen. In this study, we describe the generation of a collagen VII hypomorphic mouse that serves as an immunocompetent animal model for DEB. These mice expressed collagen VII at about 10% of normal levels, and their phenotype closely resembled characteristics of severe human DEB, including mucocutaneous blistering, nail dystrophy, and mitten deformities of the extremities. The oral blistering experienced by these mice resulted in growth retardation, and repeated blistering led to excessive induction of tissue repair, causing TGF-beta1-mediated contractile fibrosis generated by myofibroblasts and pseudosyndactyly in the extremities. Intradermal injection of WT fibroblasts resulted in neodeposition of collagen VII and functional restoration of the dermal-epidermal junction. Treated areas were also resistant to induced frictional stress. In contrast, untreated areas of the same mouse showed dermal-epidermal separation following induced stress. These data demonstrate that fibroblast-based treatment can be used to treat DEB in a mouse model and suggest that this approach may be effective in the development of clinical therapeutic regimens for patients with DEB.
Assuntos
Colágeno Tipo VII/metabolismo , Modelos Animais de Doenças , Epidermólise Bolhosa Distrófica , Fibroblastos/fisiologia , Pele/patologia , Animais , Células Cultivadas , Colágeno Tipo VII/genética , Epidermólise Bolhosa Distrófica/genética , Epidermólise Bolhosa Distrófica/fisiopatologia , Epidermólise Bolhosa Distrófica/terapia , Feminino , Fibroblastos/citologia , Deformidades Congênitas do Pé , Membro Anterior/anormalidades , Deformidades Congênitas da Mão , Humanos , Masculino , Desnutrição/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fenótipo , Splicing de RNA , Pele/anatomia & histologia , Pele/metabolismoRESUMO
PURPOSE: To compare a glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging method, which enables sampling of the water signal as a function of the presaturation offset (z-spectrum) at 13 points in clinically feasible imaging times, with sodium 23 ((23)Na) magnetic resonance (MR) imaging in patients after cartilage repair surgery (matrix-associated autologous chondrocyte transplantation and microfracture therapy). MATERIALS AND METHODS: One female patient (67.3 years), and 11 male patients (median age, 28.8 years; interquartile range [IQR], 24.6-32.3 years) were examined with a 7-T whole-body system, with approval of the local ethics committee after written informed consent was obtained. A modified three-dimensional gradient-echo sequence and a 28-channel knee coil were used for gagCEST imaging. (23)Na imaging was performed with a circularly polarized knee coil by using a modified gradient-echo sequence. Statistical analysis of differences and Spearman correlation were applied. RESULTS: The median of asymmetries in gagCEST z-spectra summed over all offsets from 0 to 1.3 ppm was 7.99% (IQR, 6.33%-8.79%) in native cartilage and 5.13% (IQR, 2.64%-6.34%) in repair tissue. A strong correlation (r = 0.701; 95% confidence interval: 0.21, 0.91) was found between ratios of signal intensity from native cartilage to signal intensity from repair tissue obtained with gagCEST or (23)Na imaging. The median of dimensionless ratios between native cartilage and repair tissue was 1.28 (IQR, 1.20-1.58) for gagCEST and 1.26 (IQR, 1.21-1.48) for (23)Na MR imaging. CONCLUSION: The high correlation between the introduced gagCEST method and (23)Na imaging implies that gagCEST is a potentially useful biomarker for glycosaminoglycans.
Assuntos
Cartilagem Articular/metabolismo , Cartilagem Articular/patologia , Glicosaminoglicanos/metabolismo , Imageamento por Ressonância Magnética/métodos , Adulto , Artroplastia Subcondral , Meios de Contraste/farmacocinética , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Isótopos de Sódio/farmacocinética , Adulto JovemRESUMO
PURPOSE: To evaluate a new isotropic 3D proton-density, turbo-spin-echo sequence with variable flip-angle distribution (PD-SPACE) sequence compared to an isotropic 3D true-fast-imaging with steady-state-precession (True-FISP) sequence and 2D standard MR sequences with regard to the new 3D magnetic resonance observation of cartilage repair tissue (MOCART) score. MATERIALS AND METHODS: Sixty consecutive MR scans on 37 patients (age: 32.8 ± 7.9 years) after matrix-associated autologous chondrocyte transplantation (MACT) of the knee were prospectively included. The 3D MOCART score was assessed using the standard 2D sequences and the multiplanar-reconstruction (MPR) of both isotropic sequences. Statistical, Bonferroni-corrected correlation as well as subjective quality analysis were performed. RESULTS: The correlation of the different sequences was significant for the variables defect fill, cartilage interface, bone interface, surface, subchondral lamina, chondral osteophytes, and effusion (Pearson coefficients 0.514-0.865). Especially between the standard sequences and the 3D True-FISP sequence, the variables structure, signal intensity, subchondral bone, and bone marrow edema revealed lower, not significant, correlation values (0.242-0.383). Subjective quality was good for all sequences (P ≥ 0.05). Artifacts were most often visible on the 3D True-FISP sequence (P < 0.05). CONCLUSION: Different isotropic sequences can be used for the 3D evaluation of cartilage repair with the benefits of isotropic 3D MRI, MPR, and a significantly reduced scan time, where the 3D PD-SPACE sequence reveals the best results.
Assuntos
Algoritmos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Meniscos Tibiais/patologia , Lesões do Menisco Tibial , Anisotropia , Condrócitos/transplante , Feminino , Humanos , Traumatismos do Joelho/patologia , Traumatismos do Joelho/cirurgia , Masculino , Meniscos Tibiais/cirurgia , Pessoa de Meia-Idade , Prótons , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Resultado do TratamentoRESUMO
OBJECT: The aim of this study was to demonstrate the feasibility of MR microimaging on a conventional 9.4 T horizontal animal MRI system using commercial available microcoils in combination with only minor modifications to the system, thereby opening this field to a larger community. MATERIALS AND METHODS: Commercially available RF microcoils designed for high-resolution NMR spectrometers were used in combination with a custom-made probehead. For this purpose, changes within the transmit chain and modifications to the adjustment routines and image acquisition sequences were made, all without requiring expensive hardware. To investigate the extent to which routine operation and high-resolution imaging is possible, the quality of phantom images was analysed. Surface and solenoidal microcoils were characterized with regard to their sensitive volume and signal-to-noise ratio. In addition, the feasibility of using planar microcoils to achieve high-resolution images of living glioma cells labelled with MnCl(2) was investigated. RESULTS: The setup presented in this work allows routine acquisition of high-quality images with high SNR and isotropic resolutions up to 10 µm within an acceptable measurement time. CONCLUSION: This study demonstrates that MR microscopy can be applied at low cost on animal MR imaging systems, which are in widespread use. The successful imaging of living glioma cells indicates that the technique promises to be a useful tool in biomedical research.
Assuntos
Aumento da Imagem/instrumentação , Imageamento por Ressonância Magnética/instrumentação , Espectroscopia de Ressonância Magnética/instrumentação , Microscopia/instrumentação , Animais , Técnicas de Cultura de Células , Desenho de Equipamento , Estudos de Viabilidade , Humanos , Espectroscopia de Ressonância Magnética/métodos , Imagens de FantasmasRESUMO
Until very recently, the study of neural architecture using fixed tissue has been a major scientific focus of neurologists and neuroanatomists. A non-invasive detailed insight into the brain's axonal connectivity in vivo has only become possible since the development of diffusion tensor magnetic resonance imaging (DT-MRI). This unique approach of analyzing axonal projections in the living brain was used in the present study to describe major white matter fiber tracts of the mouse brain and also to identify for the first time non-invasively the rich connectivity between the amygdala and different target regions. To overcome the difficulties associated with high spatially and temporally resolved DT-MRI measurements a 4-shot diffusion weighted spin echo (SE) echo planar imaging (EPI) protocol was adapted to mouse brain imaging at 9.4T. Diffusion tensor was calculated from data sets acquired by using 30 diffusion gradient directions while keeping the acquisition time at 91 min. Two fiber tracking algorithms were employed. A deterministic approach (fiber assignment by continuous tracking - FACT algorithm) allowed us to identify and generate the 3D representations of various neural pathways. A probabilistic approach was further used for the generation of probability maps of connectivity with which it was possible to investigate - in a statistical sense - all possible connecting pathways between selected seed points. We show here applications to determine the connection probability between regions belonging to the visual or limbic systems. This method does not require a priori knowledge about the projections' trajectories and is shown to be efficient even if the investigated pathway is long or three-dimensionally complex. Additionally, high resolution images of rotational invariant parameters of the diffusion tensor, such as fractional anisotropy, volume ratio or main eigenvalues allowed quantitative comparisons in-between regions of interest (ROIs) and showed significant differences between various white matter regions.
Assuntos
Encéfalo/anatomia & histologia , Imagem de Tensor de Difusão/métodos , Vias Neurais/anatomia & histologia , Algoritmos , Animais , Feminino , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , CamundongosRESUMO
We report the first published case study of a suddenly occurring panic attack in a patient with no prior history of panic disorder during combined functional magnetic resonance imaging (fMRI, 1.5 Tesla) and electrocardiogram (ECG) recording. The single case was a 46-year-old woman who developed a panic attack near the planned end of the fMRI acquisition session, which therefore had to be aborted. Correlational analysis of heart rate fluctuations and fMRI data revealed a significant negative association in the left middle temporal gyrus. Additionally, regions-of-interest (ROI) analyses indicated significant positive associations in the left amygdala, and trends towards significance in the right amygdala and left insula.
Assuntos
Encéfalo/fisiopatologia , Frequência Cardíaca , Transtorno de Pânico/fisiopatologia , Mapeamento Encefálico , Eletrocardiografia , Feminino , Coração/fisiopatologia , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Análise de Regressão , Síndrome das Pernas Inquietas/fisiopatologia , Processamento de Sinais Assistido por Computador , Fatores de Tempo , Percepção Visual/fisiologiaRESUMO
The amount and distribution of adipose tissue are important risk factors for different diseases. We present here a novel method with intrinsic water suppression (water-suppressed transition into driven equilibrium [TIDE]) and its application to healthy volunteers for fat volume and distribution evaluations. Water-suppressed TIDE revealed high image quality without artifacts, high signal-to-noise ratio of fat, and excellent suppression of water tissues, with an acquisition time of approximately 0.6 s/slice. Water-suppressed TIDE is a powerful tool for simple quantification of adipose tissue.
Assuntos
Tecido Adiposo/anatomia & histologia , Algoritmos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Reconhecimento Automatizado de Padrão/métodos , Humanos , Aumento da Imagem/métodos , Masculino , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: The pathology of restless legs syndrome (RLS) is still not understood. To investigate the pathomechanism of the disorder further we recorded a surface electromyogram (EMG) of the anterior tibial muscle during functional magnetic resonance imaging (fMRI) in patients with idiopathic RLS. METHODS: Seven subjects with moderate to severe RLS were investigated in the present pilot study. Patients were lying supine in the scanner for over 50 min and were instructed not to move voluntarily. Sensory leg discomfort (SLD) was evaluated on a 10-point Likert scale. For brain image analysis, an algorithm for the calculation of tonic EMG values was developed. RESULTS: We found a negative correlation of tonic EMG and SLD (p <0.01). This finding provides evidence for the clinical experience that RLS-related subjective leg discomfort increases during muscle relaxation at rest. In the fMRI analysis, the tonic EMG was associated with activation in motor and somatosensory pathways and also in some regions that are not primarily related to motor or somatosensory functions. CONCLUSIONS: By using a newly developed algorithm for the investigation of muscle tone-related changes in cerebral activity, we identified structures that are potentially involved in RLS pathology. Our method, with some modification, may also be suitable for the investigation of phasic muscle activity that occurs during periodic leg movements.
Assuntos
Encéfalo/fisiopatologia , Imageamento por Ressonância Magnética , Tono Muscular/fisiologia , Músculo Esquelético/fisiopatologia , Síndrome das Pernas Inquietas/fisiopatologia , Eletromiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Síndrome das Pernas Inquietas/diagnóstico , Índice de Gravidade de DoençaRESUMO
RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the feasibility and technical quality of a zoomed three-dimensional (3D) turbo spin-echo (TSE) sampling perfection with application optimized contrasts using different flip-angle evolutions (SPACE) sequence of the lumbar spine. MATERIALS AND METHODS: In this prospective feasibility study, nine volunteers underwent a 3-T magnetic resonance examination of the lumbar spine including 1) a conventional 3D T2-weighted (T2w) SPACE sequence with generalized autocalibrating partially parallel acquisition technique acceleration factor 2 and 2) a zoomed 3D T2w SPACE sequence with a reduced field of view (reduction factor 2). Images were evaluated with regard to image sharpness, signal homogeneity, and the presence of artifacts by two experienced radiologists. For quantitative analysis, signal-to-noise ratio (SNR) values were calculated. RESULTS: Image sharpness of anatomic structures was statistically significantly greater with zoomed SPACE (P < .0001), whereas the signal homogeneity was statistically significantly greater with conventional SPACE (cSPACE; P = .0003). There were no statistically significant differences in extent of artifacts. Acquisition times were 8:20 minutes for cSPACE and 6:30 minutes for zoomed SPACE. Readers 1 and 2 selected zSPACE as the preferred sequence in five of nine cases. In two of nine cases, both sequences were rated as equally preferred by both the readers. SNR values were statistically significantly greater with cSPACE. CONCLUSIONS: In comparison to a cSPACE sequences, zoomed SPACE imaging of the lumbar spine provides sharper images in conjunction with a 25% reduction in acquisition time.
Assuntos
Interpretação de Imagem Assistida por Computador , Imageamento Tridimensional , Vértebras Lombares/anatomia & histologia , Imageamento por Ressonância Magnética , Adulto , Idoso , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Estudos Prospectivos , Valores de Referência , Razão Sinal-RuídoRESUMO
Objective: To investigate the factors associated with cartilage proteoglycan content in patients with rheumatoid arthritis (RA) Methods: 32 RA patients received high-field 3 Tesla Gadolinium-Enhanced MRI of Cartilage (dGEMRIC) for determining cartilage proteoglycan content. Measurements were performed in three individual cartilage regions (medial, central, lateral) of the metacarpophalangeal joints 2 and 3. dGEMRIC values were then related to disease duration, disease activity, anti-citrullinated protein antibody (ACPA) status, rheumatoid factor status and C-reactive protein level. Results: dGEMRIC values were not significantly different between the MCP2 and MCP3 joint. Inter-class correlations were high (>0.92) for all three (medial, central and lateral) cartilage compartments. dGEMRIC values were significantly lower in RA patients with longer disease duration (≥3 years) and those with ACPA positivity than those with a short disease duration (<3 years)(p=0.034) or negative ACPA (p=0.0002), respectively. In contrast, no association between cartilage proteoglycan content and disease activity, C-reactive protein level and rheumatoid factor status was found. Conclusion: Decreased cartilage proteoglycan content in RA patients is associated with disease duration and ACPA positivity but not with the actual disease activity, CRP level or rheumatoid factor status. These data suggest that the cumulative burden of inflammation as well as ACPA are the determinants for cartilage damage in RA.
Assuntos
Artrite Reumatoide/imunologia , Autoanticorpos/análise , Cartilagem/química , Articulação Metacarpofalângica/imunologia , Proteoglicanas/análise , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
PURPOSE: To determine the accuracy and reliability of three-dimensional (3D) T1- and proton density (PD)-weighted turbo spin-echo (TSE) sampling perfection with application-optimized contrasts using different flip-angle evolution (SPACE) compared with conventional 2D sequences in assessment of the shoulder-joint. MATERIALS AND METHODS: Ninety-three subjects were examined on a 3-T MRI system with both conventional 2D-TSE sequences in T1-, T2- and PD-weighting and 3D SPACE sequences in T1- and PD-weighting. All examinations were assessed independently by two reviewers for common pathologies of the shoulder-joint. Agreement between 2D- and 3D-sequences and inter-observer-agreement was evaluated using kappa-statistics. RESULTS: Using conventional 2D TSE sequences as standard of reference, sensitivity, specificity, and accuracy values of 3D SPACE were 81.8%, 95.1%, and 93.5% for injuries of the supraspinatus-tendon (SSP), 81.3%, 93.5%, and 91.4% for the cartilage layer and 82.4%, 98.5%, and 97.5% for the long biceps tendon. Concordance between 2D and 3D was almost perfect for tendinopathies of the SSP (κ=0.85), osteoarthritis (κ=1), luxation of the biceps tendon (κ=1) and adjacent bone marrow (κ=0.92). Inter-observer-agreement was generally higher for conventional 2D TSE sequences (κ, 0.23-1.0), when compared to 3D SPACE sequences (κ, -0.33 to 1.0) except for disorders of the long biceps tendon and supraspinatus tendon rupture. CONCLUSION: Because of substantial and almost perfect concordance with conventional 2D TSE sequences for common shoulder pathologies, MRI examination-time can be reduced by nearly 40% (up to 11 min) using 3D-SPACE without loss of information.
Assuntos
Aumento da Imagem/métodos , Imageamento Tridimensional , Imageamento por Ressonância Magnética/métodos , Articulação do Ombro/anatomia & histologia , Adulto , Anisotropia , Artefatos , Voluntários Saudáveis , Humanos , Interpretação de Imagem Assistida por Computador/métodos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Fatores de TempoRESUMO
OBJECTIVES: To evaluate the clinical usefulness of an optimized 3D-Fast-Spin-Echo-sequence (3D-SPACE) in combination with a 15-channel knee-coil for 3D-imaging of the knee at 3T. METHODS: 15 volunteers and 50 consecutive patients were examined at 3 T with fat-saturated moderately T2-weighted 3D-SPACE (Voxel-size (VS): 0.6 mm×0.5 mm×0.5 mm/acquisition-time (AT) 10:44 min) using a 15-channel knee-coil. Flip angle optimization and radial k-space reordering were applied. Signal- and contrast-to-noise-ratios (SNR, CNR) were compared to non-optimized 3D-SPACE (8-channel knee-coil) and conventional 2D-FSE (VS: 0.4 mm×0.4 mm×3 mm/total AT: 12 min). Two radiologists independently rated depiction of internal knee structures and assessed detection and depiction of cartilage and meniscus abnormalities compared to conventional 2D-FSE-sequences. Sensitivity and specificity were calculated for a subgroup with arthroscopy as reference standard. Statistical analysis was performed with paired t-tests, confidence intervals and weighted-κ-coefficients. RESULTS: SNR and CNR particularly of fluid/cartilage of optimized 3D-SPACE were significantly higher (p<0.05) than of the non-optimized 3D-sequence and conventional 2D-sequence. Blurring and image inhomogeneity were reduced in the optimized sequence. The thin slice-thickness was beneficial for depiction of problematical anatomical structures such as meniscal roots. 3D-SPACE showed significantly higher diagnostic confidence (p<0.05) for diagnosis of cartilage lesions of the femoral trochlea. Overall sensitivity and specificity of 3D-SPACE and 2D-FSE for cartilage lesions was 82.3%/80.2% and 79.4%/84.2% and 100%/86.4% and 92.3%/81.8% for meniscus lesions. CONCLUSIONS: Optimized 3D-SPACE provides significantly higher signal and contrast compared to conventional 2D-FSE, particularly for fluid and cartilage, leading to improved diagnostic confidence, particularly in problematic areas, such as the femoral trochlea.