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1.
Medicine (Baltimore) ; 99(41): e22656, 2020 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-33031328

RESUMO

RATIONALE: Intracranial small aneurysm is a rare cause of ischemic stroke, and been described only in sparse case reports. The exact pathophysiology, treatment strategies, and prognosis remain incompletely understood. PATIENT CONCERNS: A 42-year-old man presented with an acute onset weakness of the right limbs. DIAGNOSES: Neuroimaging evaluation confirmed a diagnosis of acute ischemic stroke and left internal carotid artery (ICA) small aneurysm. INTERVENTIONS: The patient underwent oral anti-platelet therapy (100 mg aspirin daily). OUTCOMES: The patient recovered to normal status within 4 weeks following antiplatelet treatment. During a follow-up period of 1 year, he remained neurologically asymptomatic and led a virtually normal life. LESSONS: It is crucial for clinicians to be aware of this entity, as cerebral infarction caused by small cerebral aneurysm is extremely rare.


Assuntos
Doenças das Artérias Carótidas/complicações , Artéria Carótida Interna , Aneurisma Intracraniano/complicações , Acidente Vascular Cerebral/etiologia , Adulto , Imagem de Difusão por Ressonância Magnética , Humanos , Masculino , Acidente Vascular Cerebral/diagnóstico por imagem
2.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 1671-1674, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018317

RESUMO

In the last decade, multiparametric magnetic resonance imaging (mpMRI) has been expanding its role in prostate cancer detection and characterization. In this work, 19 patients with clinically significant peripheral zone (PZ) tumours were studied. Tumour masks annotated on the whole-mount histology sections were mapped on T2-weighted (T2w) and diffusion-weighted (DW) sequences. Gray-level histograms of tumoral and normal tissue were compared using six first-order texture features. Multivariate analysis of variance (MANOVA) was used to compare group means. Mean intensity signal of ADC showed the highest showed the highest area under the receiver operator characteristics curve (AUC) equal to 0.85. MANOVA analysis revealed that ADC features allows a better separation between normal and cancerous tissue with respect to T2w features (ADC: P = 0.0003, AUC = 0.86; T2w: P = 0.03, AUC = 0.74). MANOVA proved that the combination of T2-weighted and apparent diffusion coefficient (ADC) map features increased the AUC to 0.88. Histogram-based features extracted from invivo mpMRI can help discriminating significant PZ PCa.


Assuntos
Neoplasias da Próstata , Imagem de Difusão por Ressonância Magnética , Humanos , Espectroscopia de Ressonância Magnética , Masculino , Imageamento por Ressonância Magnética Multiparamétrica , Neoplasias da Próstata/diagnóstico por imagem
3.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 1679-1682, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018319

RESUMO

Epilepsy is one of the largest neurological diseases in the world, and juvenile myoclonic epilepsy (JME) usually occurs in adolescents, giving patients tremendous burdens during growth, which really needs the early diagnosis. Advanced diffusion magnetic resonance imaging (MRI) could detect the subtle changes of the white matter, which could be a non-invasive early diagnosis biomarker for JME. Transfer learning can solve the problem of insufficient clinical samples, which could avoid overfitting and achieve a better detection effect. However, there is almost no research to detect JME combined with diffusion MRI and transfer learning. In this study, two advanced diffusion MRI methods, high angle resolved diffusion imaging (HARDI) and neurite orientation dispersion and density imaging (NODDI), were used to generate the connectivity matrix which can describe tiny changes in white matter. And three advanced convolutional neural networks (CNN) based transfer learning were applied to detect JME. A total of 30 participants (15 JME patients and 15 normal controls) were analyzed. Among the three CNN models, Inception_resnet_v2 based transfer learning is better at detecting JME than Inception_v3 and Inception_v4, indicating that the "short cut" connection can improve the ability to detect JME. Inception_resnet_v2 achieved to detect JME with the accuracy of 75.2% and the AUC of 0.839. The results support that diffusion MRI and CNN based transfer learning have the potential to improve the automated detection of JME.


Assuntos
Epilepsia Mioclônica Juvenil , Adolescente , Imagem de Difusão por Ressonância Magnética , Humanos , Aprendizado de Máquina , Imagem por Ressonância Magnética , Epilepsia Mioclônica Juvenil/diagnóstico , Redes Neurais de Computação
4.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 1705-1708, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018325

RESUMO

Primary open angle glaucoma (POAG) is one of the most common causes of permanent blindness in the world. Recent studies have originated the hypothesis that POAG could be considered as a central nervous system pathology which results in secondary visual involvement. The aim of this study is to assess possible structural whole brain connectivity alterations in POAG by combining multi-shell diffusion weighted imaging, multi-shell multi-tissue probabilistic tractography, graph theoretical measures and a newly designed disruption index, which evaluates the global reorganization of brain networks in group-wise comparisons. We found global differences in structural connectivity between Glaucoma patients and controls, as well as in local graph theoretical measures. These changes extended well beyond the primary visual pathway. Furthermore, group-wise and subject-wise disruption indices were found to be statistically different between glaucoma patients and controls, with a positive slope. Overall, our results support the hypothesis of a whole-brain structural reorganization in glaucoma which is specific to structural connectivity, possibly placing this disease within the recently defined groups of brain disconnection syndrome.


Assuntos
Encéfalo , Glaucoma de Ângulo Aberto , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Imagem de Difusão por Ressonância Magnética , Substância Cinzenta , Humanos
5.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 1709-1713, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018326

RESUMO

Contemporary diffusion MRI based analysis with HARDI, which provides more accurate fiber orientation, can be performed using single or multiple b-values (single or multi-shell). Single shell HARDI cannot provide volume fraction for different tissue types, which can produce bias and noisier results in estimation of fiber ODF. Multi-shell acquisition can resolve this issue. However, it requires more scanning time and is therefore not very well suited in clinical setting. Considering this, we propose a novel deep learning architecture, MSR-Net, for reconstruction of diffusion MRI volumes for some b-value using acquisitions at another b-value. In this work, we demonstrate this for b = 2000 s/mm2 and b = 1000 s/mm2. We learn such a transformation in the space of spherical harmonic coefficients. The proposed network consists of encoder-decoder along-with an attention module and a feature module. We have considered L2 and Content loss for optimizing and improving the performance. We have trained and validated the network using the HCP data-set with standard qualitative and quantitative performance measures.


Assuntos
Algoritmos , Imagem por Ressonância Magnética , Atenção , Imagem de Difusão por Ressonância Magnética , Orientação Espacial
6.
Nan Fang Yi Ke Da Xue Xue Bao ; 40(4): 459-462, 2020 Apr 30.
Artigo em Chinês | MEDLINE | ID: mdl-32895146

RESUMO

Diffusion-weighted imaging (DWI) is currently the most sensitive technique to diagnose early ischemic stroke. DWI signal hyperintensity is usually considered to suggest irreversible infarct core, but recent studies demonstrated that DWI hyperintensity signal could be reversible on small embolic lesions. Herein we present a case in a 63-year-old male patient, who was admitted to the emergency department with altered mental status and complaint of weakness in the left arm and leg 6.8 h prior to the admission. Emergency cranial magnetic resonance imaging (MRI) and angiography (MRA) revealed occlusion of his right middle cerebral artery (MCA) and large lesions on DWI. The patient underwent intra-artery thrombectomy after evaluation in spite of the large volume of the DWI lesions up to 91.5 mL at the baseline. His right MCA was recanalized at 8.5 h from symptom onset. One week after the procedure, the patient showed reduced DWI lesion volume to 11.58 mL. In this case we observed the reversibility of a large lesion of the anterior artery circulation presenting with hyperintensity on DWI, suggesting that the clinical implication of DWI hyperintensity should be interpreted with caution, and a large volume of baseline DWI hyperintensity may not be a contraindication to thrombectomy. This conclusion, however, awaits further validation by future large-scale randomized controlled trials.


Assuntos
Infarto da Artéria Cerebral Média , Acidente Vascular Cerebral , Imagem de Difusão por Ressonância Magnética , Humanos , Infarto da Artéria Cerebral Média/diagnóstico por imagem , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Trombectomia
7.
Medicine (Baltimore) ; 99(38): e22305, 2020 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-32957391

RESUMO

RATIONALE: A developmental venous anomaly (DVA) is the most common intracranial congenital anomaly and is mostly asymptomatic. Thrombosis rarely develops in a DVA due to hypercoagulation. We report a case of ischemic stroke in the area of a DVA after minor head trauma in a patient with DVA and without a predisposition thrombosis. PATIENT CONCERNS: A healthy 17-year-old male was admitted to the emergency room due to left hemiparesis, which was caused by a ball hitting the right side of his head during a soccer game. DIAGNOSIS: Brain magnetic resonance (MR) susceptibility-weighted image showed several small veins draining to the central vein in the area from the right posterior putamen to the periventricular white matter. INTERVENTIONS: We diagnosed the patient with an ischemic stroke associated with a DVA and administered antiplatelet agents. The patient's autoantibodies (including antiphospholipid antibody) and factors of blood coagulation were normal. OUTCOMES: The left hemiparesis of the patient worsened by the second day of admission. Moreover, high signal intensity was observed in the DVA region of the diffusion weighted image of brain MR. The patient's symptoms gradually improved afterward, and left hemiparesis recovered fully 3 weeks after the onset. LESSONS: DVAs may predispose to ischemic stroke due to thrombosis and hypercoagulation, although it is rare. It is necessary to consider the possibility of ischemic stroke due to minor head trauma, even without factors causing hypercoagulation.


Assuntos
Concussão Encefálica/complicações , Acidente Vascular Cerebral/etiologia , Adolescente , Concussão Encefálica/diagnóstico por imagem , Ventrículos Cerebrais/diagnóstico por imagem , Ventrículos Cerebrais/patologia , Imagem de Difusão por Ressonância Magnética , Humanos , Angiografia por Ressonância Magnética , Masculino , Inibidores da Agregação de Plaquetas/uso terapêutico , Futebol/lesões , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/tratamento farmacológico
8.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao ; 42(4): 444-451, 2020 Aug 30.
Artigo em Chinês | MEDLINE | ID: mdl-32895095

RESUMO

Objective To explore the utility of apparent diffusion coefficient(ADC)histogram analysis for differentiating genetic subtypes of diffuse lower-grade gliomas. Methods A total of 55 patients with WHO grade Ⅱ/Ⅲ diffuse lower-grade gliomas who underwent preoperative routine brain magnetic resonance imaging and diffusion weighted imaging in our center were retrospectively evaluated.Among whom there were 14 patients with isocitrate dehydrogenase(IDH)wild-type gliomas(IDH wt group),19 patients with IDH-mutant 1p19q intact gliomas(IDH mut1p19q int group),and 22 patients with IDH-mutant 1p19q co-deleted gliomas(IDH mut1p19q del group).The whole-lesion ADC values derived from histogram analysis(including ADCmean,ADCminimum,ADC5%,ADC10%,ADC25%,ADC50%,ADC75%,ADC90%,ADC95%,ADCmaximum,mode,range,skewness,kurtosis,standard deviation,inhomogeneity,and entrophy)were measured for each patient.All parameters between the different genetic subtypes were compared by using the Student's t test or Mann-Whitney U test.Receiver operating curve(ROC)analysis was used to assess the diagnostic performance of ADC histogram in distinguishing the different genetic subtypes. Results Compared with IDH wt group,the ADC75%(P=0.021),ADC90%(P=0.015),ADC95%(P=0.014),ADCmaximum (P=0.035),range(P=0.009),standard deviation(P=0.001)and inhomogeneity(P=0.001)were significantly lower in IDH mut group;in contrast,the ADCminimum (P=0.031)and kurtosis(P=0.020)of IDH mut group were significantly higher than those in IDH wt group.The ADCmean(P=0.010),ADC5%(P=0.016),ADC10%(P=0.012),ADC25%(P=0.007),ADC50%(P=0.005),ADC75%(P=0.015),and mode(P=0.002)were significantly higher in IDH mut1p19q int group than in IDH mut1p19q del group.Inhomogeneity achieved the highest area under ROC(AUC)(0.811)in differentiating IDH mut gliomas and IDH wt gliomas,with a cutoff value of 0.229;the sensitivity and specificity were 85.7% and 73.2%.The mode achieved the highest AUC(0.744)in differentiating IDH mut1p19q int gliomas and IDH mut1p19q del gliomas,with a cutoff value was 1448.75×10 -6 mm 2/s;the sensitivity and specificity were 57.9% and 90.9%.Conclusion ADC histograms analysis may be helpful to differentiate genetic subtypes in lower-grade gliomas.


Assuntos
Neoplasias Encefálicas , Glioma , Imagem de Difusão por Ressonância Magnética , Humanos , Curva ROC , Estudos Retrospectivos
9.
Nat Commun ; 11(1): 4803, 2020 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-32968068

RESUMO

Meningiomas are the most common primary intracranial tumors, but the molecular drivers of meningioma tumorigenesis are poorly understood. We hypothesized that investigating intratumor heterogeneity in meningiomas would elucidate biologic drivers and reveal new targets for molecular therapy. To test this hypothesis, here we perform multiplatform molecular profiling of 86 spatially-distinct samples from 13 human meningiomas. Our data reveal that regional alterations in chromosome structure underlie clonal transcriptomic, epigenomic, and histopathologic signatures in meningioma. Stereotactic co-registration of sample coordinates to preoperative magnetic resonance images further suggest that high apparent diffusion coefficient (ADC) distinguishes meningioma regions with proliferating cells enriched for developmental gene expression programs. To understand the function of these genes in meningioma, we develop a human cerebral organoid model of meningioma and validate the high ADC marker genes CDH2 and PTPRZ1 as potential targets for meningioma therapy using live imaging, single cell RNA sequencing, CRISPR interference, and pharmacology.


Assuntos
Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Perfilação da Expressão Gênica/métodos , Heterogeneidade Genética , Imagem por Ressonância Magnética/métodos , Neoplasias Meníngeas/genética , Neoplasias Meníngeas/metabolismo , Idoso , Antígenos CD/genética , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/patologia , Caderinas/genética , Imagem de Difusão por Ressonância Magnética/métodos , Epigenômica , Feminino , Marcadores Genéticos , Genômica , Humanos , Neoplasias Meníngeas/diagnóstico por imagem , Neoplasias Meníngeas/patologia , Proteínas Tirosina Fosfatases Classe 5 Semelhantes a Receptores/genética , Transcriptoma
10.
Br J Radiol ; 93(1114): 20200543, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32877210

RESUMO

OBJECTIVES: To evaluate interobserver agreement for T2 weighted (T2W) and diffusion-weighted MRI (DW-MRI) contours of locally advanced rectal cancer (LARC); and to evaluate manual and semi-automated delineations of restricted diffusion tumour subvolumes. METHODS: 20 cases of LARC were reviewed by 2 radiation oncologists and 2 radiologists. Contours of gross tumour volume (GTV) on T2W, DW-MRI and co-registered T2W/DW-MRI were independently delineated and compared using Dice Similarity Coefficient (DSC), mean distance to agreement (MDA) and other metrics of interobserver agreement. Restricted diffusion subvolumes within GTVs were manually delineated and compared to semi-automatically generated contours corresponding to intratumoral apparent diffusion coefficient (ADC) centile values. RESULTS: Observers were able to delineate subvolumes of restricted diffusion with moderate agreement (DSC 0.666, MDA 1.92 mm). Semi-automated segmentation based on the 40th centile intratumoral ADC value demonstrated moderate average agreement with consensus delineations (DSC 0.581, MDA 2.44 mm), with errors noted in image registration and luminal variation between acquisitions. A small validation set of four cases with optimised planning MRI demonstrated improvement (DSC 0.669, MDA 1.91 mm). CONCLUSION: Contours based on co-registered T2W and DW-MRI could be used for delineation of biologically relevant tumour subvolumes. Semi-automated delineation based on patient-specific intratumoral ADC thresholds may standardise subvolume delineation if registration between acquisitions is sufficiently accurate. ADVANCES IN KNOWLEDGE: This is the first study to evaluate the feasibility of semi-automated diffusion-based subvolume delineation in LARC. This approach could be applied to dose escalation or 'dose painting' protocols to improve delineation reproducibility.


Assuntos
Adenocarcinoma/diagnóstico por imagem , Imagem de Difusão por Ressonância Magnética/métodos , Interpretação de Imagem Assistida por Computador/métodos , Neoplasias Retais/diagnóstico por imagem , Adenocarcinoma/patologia , Adenocarcinoma/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Competência Clínica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Variações Dependentes do Observador , Neoplasias Retais/patologia , Neoplasias Retais/terapia , Reprodutibilidade dos Testes , Estudos Retrospectivos , Carga Tumoral
11.
Am J Vet Res ; 81(10): 796-803, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32969732

RESUMO

OBJECTIVE: To determine the change in mean hepatic apparent diffusion coefficient (ADC) and hepatic fat fraction (HFF) during body weight gain in cats by use of MRI. ANIMALS: 12 purpose-bred adult neutered male cats. PROCEDURES: The cats underwent general health and MRI examination at time 0 (before dietary intervention) and time 1 (after 40 weeks of being fed high-energy food ad libitum). Sequences included multiple-echo gradient-recalled echo MRI and diffusion-weighted MRI with 3 b values (0, 400, and 800 s/mm2). Variables (body weight and the HFF and ADC in selected regions of interest in the liver parenchyma) were compared between time points by Wilcoxon paired-sample tests. Relationships among variables were assessed with generalized mixed-effects models. RESULTS: Median body weight was 4.5 and 6.5 kg, mean ± SD HFF was 3.39 ± 0.89% and 5.37 ± 1.92%, and mean ± SD hepatic ADC was 1.21 ± 0.08 × 10-3 mm2/s and 1.01 ± 0.2 × 10-3 mm2/s at times 0 and 1, respectively. Significant differences between time points were found for body weight, HFF, and ADC. The HFF was positively associated with body weight and ADC was negatively associated with HFF. CONCLUSIONS AND CLINICAL RELEVANCE: Similar to findings in people, cats had decreasing hepatic ADC as HFF increased. Protons associated with fat tissue in the liver may reduce diffusivity, resulting in a lower ADC than in liver with lower HFF. Longer studies and evaluation of cats with different nutritional states are necessary to further investigate these findings.


Assuntos
Doenças do Gato , Imagem de Difusão por Ressonância Magnética , Animais , Peso Corporal , Gatos , Fígado/diagnóstico por imagem , Imagem por Ressonância Magnética , Masculino , Ganho de Peso
12.
J Cardiovasc Magn Reson ; 22(1): 69, 2020 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-32951605

RESUMO

PURPOSE: Common types of congenital heart disease exhibit a variety of structural and functional variations which may be accompanied by changes in the myocardial microstructure. We aimed to compare myocardial architecture from magnetic resonance diffusion tensor imaging (DTI) in preserved pathology specimens. MATERIALS AND METHODS: Pathology specimens (n = 24) formalin-fixed for 40.8 ± 7.9 years comprised tetralogy of Fallot (TOF, n = 10), dextro-transposition of great arteries (D-TGA, n = 8) five with ventricular septal defect (VSD), systemic right ventricle (n = 4), situs inversus totalis (SIT, n = 1) and levo-TGA (L-TGA, n = 1). Specimens were imaged using a custom spin-echo sequence and segmented automatically according to tissue volume fraction. In each specimen T1, T2, fractional anisotropy, mean diffusivity, helix angle (HA) and sheet angle (E2A) were quantified. Pathologies were compared according to their HA gradient, HA asymmetry and E2A mean value in each myocardial segment (anterior, posterior, septal and lateral walls). RESULTS: TOF and D-TGA with VSD had decreased helix angle gradient by - 0.34°/% and remained symmetric in the septum in comparison to D-TGA without VSD. Helix angle range was decreased by 45°. It was associated with a decreased HA gradient in the right ventricular (RV) wall, i.e. predominant circumferential myocytes. The sheet angle in the septum of TOF was opposing those of the left ventricular (LV) free wall. Univentricular systemic RV had the lowest HA gradient (- 0.43°/%) and the highest HA asymmetry (75%). HA in SIT was linear, asymmetric, and reversed with a sign change at about 70% of the depth at mid-ventricle. In L-TGA with VSD, HA was asymmetric (90%) and its gradients were decreased in the septum, anterior and lateral wall. CONCLUSION: The organization of the myocytes as determined by DTI differs between TOF, D-TGA, L-TGA, systemic RV and SIT specimens. These differences in cardiac structure may further enlighten our understanding of cardiac function in these diverse congenital heart diseases.


Assuntos
Imagem de Difusão por Ressonância Magnética , Ventrículos do Coração/diagnóstico por imagem , Miocárdio/patologia , Tetralogia de Fallot/diagnóstico por imagem , Adulto , Feminino , Ventrículos do Coração/anormalidades , Ventrículos do Coração/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Tetralogia de Fallot/patologia , Tetralogia de Fallot/fisiopatologia , Função Ventricular Esquerda , Função Ventricular Direita
13.
PLoS One ; 15(8): e0238166, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853252

RESUMO

BACKGROUND: The purpose of this study was to determine whether whole-body MRI (WBMRI) with diffusion-weighted sequences, which is free of ionizing radiation, can perform as well as traditional methods when used alone for staging or follow-up of pediatric cancer patients. METHODS: After obtaining approval from our institutional research ethics committee and appropriate informed consent, we performed 34 examinations in 32 pediatric patients. The examinations were anonymized and analyzed by two radiologists with at least 10 years' experience. RESULTS: The sensitivity and specificity findings, respectively, were as follows: 100% and 100% for primary tumor; 100% and 86% for bone metastasis; 33% and 100% for lung metastasis; 85% and 100% for lymph node metastasis; and 100% and 62% for global investigation of primary or secondary neoplasias. We observed excellent interobserver agreement for WBMRI and excellent agreement with standard staging examination results. CONCLUSIONS: Our results suggest that pediatric patients can be safely imaged with WBMRI, although not as the only tool but in association with low-dose chest CT (for subcentimeter pulmonary nodules). However, additional exams with ionizing radiation may be necessary for patients who tested positive to correctly quantify and locate the lesions.


Assuntos
Neoplasias/patologia , Adolescente , Criança , Pré-Escolar , Estudos Transversais , Imagem de Difusão por Ressonância Magnética/métodos , Feminino , Humanos , Masculino , Estadiamento de Neoplasias/métodos , Estudos Prospectivos , Sensibilidade e Especificidade , Imagem Corporal Total/métodos
14.
PLoS One ; 15(7): e0236418, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32735601

RESUMO

Diffusion magnetic resonance images may suffer from geometric distortions due to susceptibility induced off resonance fields, which cause geometric mismatch with anatomical images and ultimately affect subsequent quantification of microstructural or connectivity indices. State-of-the art diffusion distortion correction methods typically require data acquired with reverse phase encoding directions, resulting in varying magnitudes and orientations of distortion, which allow estimation of an undistorted volume. Alternatively, additional field maps acquisitions can be used along with sequence information to determine warping fields. However, not all imaging protocols include these additional scans and cannot take advantage of state-of-the art distortion correction. To avoid additional acquisitions, structural MRI (undistorted scans) can be used as registration targets for intensity driven correction. In this study, we aim to (1) enable susceptibility distortion correction with historical and/or limited diffusion datasets that do not include specific sequences for distortion correction and (2) avoid the computationally intensive registration procedure typically required for distortion correction using structural scans. To achieve these aims, we use deep learning (3D U-nets) to synthesize an undistorted b0 image that matches geometry of structural T1w images and intensity contrasts from diffusion images. Importantly, the training dataset is heterogenous, consisting of varying acquisitions of both structural and diffusion. We apply our approach to a withheld test set and show that distortions are successfully corrected after processing. We quantitatively evaluate the proposed distortion correction and intensity-based registration against state-of-the-art distortion correction (FSL topup). The results illustrate that the proposed pipeline results in b0 images that are geometrically similar to non-distorted structural images, and more closely match state-of-the-art correction with additional acquisitions. In addition, we show generalizability of the proposed approach to datasets that were not in the original training / validation / testing datasets. These datasets included varying populations, contrasts, resolutions, and magnitudes and orientations of distortion and show efficacious distortion correction. The method is available as a Singularity container, source code, and an executable trained model to facilitate evaluation.


Assuntos
Encéfalo/diagnóstico por imagem , Imagem de Difusão por Ressonância Magnética/métodos , Processamento de Imagem Assistida por Computador/métodos , Algoritmos , Artefatos , Imagem Ecoplanar/métodos , Humanos
15.
Clin Imaging ; 67: 152-159, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32739735

RESUMO

OBJECTIVES: To explore the feasibility of texture analysis based on T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) images and apparent diffusion coefficient (ADC) maps in the assessment of the severity and prognosis of ischaemic stroke using the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin scale (mRS) scores, respectively. METHODS: Overall, 116 patients diagnosed with subacute ischaemic stroke were included in this retrospective study. Based on T2-FLAIR images and ADC maps, 15 texture features were extracted from the ROIs of each patient using grey-level co-occurrence matrix (GLCM) and local binary pattern histogram Fourier (LBP-HF) methods. The correlations of NIHSS score on admission (NIHSSbaseline), NIHSS score 24 h after stroke onset (NIHSS24h) and mRS score with the texture features were evaluated using Spearman's partial correlations. The receiver operating characteristic (ROC) curve was used to compare the performance of the selected texture features in the evaluation of stroke severity and prognosis. RESULTS: Texture features derived from the T2-FLAIR images and ADC maps were correlated with NIHSS score and mRS score. EntropyADC and 0.75QuantileT2-FLAIR showed the best diagnostic performance for assessing stroke severity. The combination of EntropyADC and 0.75QuantileT2-FLAIR achieved a better performance in the evaluation of stroke severity (AUC = 0.7, p = 0.01) than either feature alone. Only 0.05QuantileT2-FLAIR was found to be correlated with mRS score, and none of the texture features were predictive of mRS score. CONCLUSION: Texture features derived from T2-FLAIR images and ADC maps might serve as biomarkers to evaluate stroke severity, but were insufficient to predict stroke prognosis.


Assuntos
Isquemia Encefálica/diagnóstico por imagem , Acidente Vascular Cerebral/diagnóstico por imagem , Idoso , Imagem de Difusão por Ressonância Magnética/métodos , Feminino , Humanos , Imagem por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Prognóstico , Curva ROC , Estudos Retrospectivos
16.
Clin Imaging ; 67: 177-188, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32829150

RESUMO

OBJECTIVE: This study sought to assess the feasibility of diffusion tensor imaging (DTI) to noninvasively evaluate histological grade and lymph node metastasis in patients with rectal carcinoma (RC). METHODS: Thirty-seven consecutive patients with histologically confirmed RC were examined by 1.5-T MRI. DTI was performed using a single-shot echo-planar imaging sequence with b values of 0 and 1000 s/mm2 and motion-probing gradients in nine noncollinear directions. Fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) maps were compared with histopathological findings. RESULTS: The FA values (0.357 ±â€¯0.047) of the RCs were significantly lower than those of the normal rectal wall, muscle, prostate, and uterus (P < 0.001 for all), while the AD, MD, and RD values (1.221 ±â€¯0.131, 0.804 ±â€¯0.075, and 0.667 ±â€¯0.057 × 10-3 mm2/s, respectively) were also significantly lower than their respective normal values (P < 0.001 for all). The FA, AD, MD, and RD values for RC additionally showed significant inverse correlations with histological grades (r = -0.781, r = -0.750, r = -0.718, and r = -0.682, respectively; P < 0.001 for all). Further, the FA (0.430 vs. 0.611), AD (1.246 vs. 1.608 × 10-3 mm2/s), MD (0.776 vs. 1.036 × 10-3 mm2/s), and RD (0.651 vs. 0.824 × 10-3 mm2/s) (P < 0.001 for all) of the metastatic and nonmetastatic lymph nodes were significantly different. CONCLUSIONS: DTI may be clinically useful for the noninvasive evaluation of histological grade and lymph node metastasis in patients with RC.


Assuntos
Carcinoma/diagnóstico por imagem , Neoplasias Retais/diagnóstico por imagem , Anisotropia , Imagem de Difusão por Ressonância Magnética , Imagem de Tensor de Difusão/métodos , Imagem Ecoplanar , Feminino , Humanos , Linfonodos , Metástase Linfática , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Útero
17.
J Comput Assist Tomogr ; 44(5): 759-765, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32842061

RESUMO

OBJECTIVE: To compare the intravoxel incoherent motion (IVIM) parameters of rectal tumors before and after lumen distension obtained with sonography transmission gel. METHODS: Twenty-five patients were enrolled. The multiple b values of IVIM including 0, 20, 50, 100, 150, 200, 400, 600, 800, 1000, 1500, and 2000 s/mm. Two blinded readers have drawn the region of interests and calculated the D, D*, and f values. Interobserver variability between the 2 readers was measured by intraclass correlation coefficients and Altman-Bland plots. The intergroup differences of the average values were compared with the paired sample t test. RESULTS: After distention, the interrater agreement of the D* value increased obviously (from 0.547 to 0.692) and that of the D and f values increased slightly (from 0.731 and 0.618 to 0.807 and 0.666). The difference in the D value had statistical significance (P = 0.0043). CONCLUSIONS: Intraluminal distension can increase the repeatability of IVIM parameters and the value of IVIM.


Assuntos
Imagem de Difusão por Ressonância Magnética/métodos , Géis/uso terapêutico , Neoplasias Retais/diagnóstico por imagem , Reto/diagnóstico por imagem , Adulto , Meios de Contraste , Feminino , Humanos , Interpretação de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Movimento/fisiologia , Variações Dependentes do Observador , Neoplasias Retais/fisiopatologia , Reto/fisiopatologia , Ultrassonografia
18.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 55(8): 595-598, 2020 Aug 09.
Artigo em Chinês | MEDLINE | ID: mdl-32842353

RESUMO

Magnetic resonance imaging is most frequently used for pre-surgical diagnosis and follow-up in salivary gland neoplasms. As for traditional techniques, dynamic contrast-enhanced and diffusion-weighted imaging are two magnetic resonance sequences commonly used in clinic, in spite of their relatively lower sensitivity and specificity. Recently, a novel magnetic resonance technique, amide proton transfer-MRI (APT-MRI), gets a lot of attention due to its special imaging principle and higher sensitivity and specificity for many human tumors diagnosis. Moreover, some studies applied this new MRI technique successfully to the diagnosis and differential diagnosis of salivary gland neoplasms. In this review, we are going to focus on the basic principle of APT-MRI and its clinical applications in salivary gland neoplasms, with a comparison of traditional MRI sequences. We will also give some prospects based on these preliminary applications in APT-MRI diagnosis for salivary gland neoplasms.


Assuntos
Imagem por Ressonância Magnética , Neoplasias das Glândulas Salivares/diagnóstico por imagem , Amidas , Imagem de Difusão por Ressonância Magnética , Humanos , Prótons
20.
Yonsei Med J ; 61(8): 736-738, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32734739

RESUMO

Remote intracerebral hemorrhage (ICH) is defined as an ICH that occurs at a distant site from the treated lesion and is a considerable post-neurointerventional complication. Because such a life-threatening complication should not be neglected, we report our experience with delayed remote ICH in a patient with symptomatic intracranial atherosclerotic stenosis (ICAS) treated by Wingspan stenting following on-label usage guidelines. A middle-aged person suffered a lobar-type subcortical hemorrhage on the left temporal lobe 22 days after Wingspan stenting in the left internal carotid artery. The present case seemed to correspond with a previous report in which remote ICH tended to occur as an ipsilateral lobar-type hemorrhage in patients with unruptured intracranial aneurysm on the internal carotid artery undergoing treatment with stents or flow diverters. Delayed remote ICH should be considered as a potential risk of using a Wingspan stent covering the carotid siphon for ICAS.


Assuntos
Artéria Carótida Interna/patologia , Artéria Carótida Interna/cirurgia , Estenose das Carótidas/cirurgia , Hemorragia Cerebral/etiologia , Stents/efeitos adversos , Idoso , Artéria Carótida Interna/diagnóstico por imagem , Estenose das Carótidas/diagnóstico por imagem , Hemorragia Cerebral/diagnóstico por imagem , Imagem de Difusão por Ressonância Magnética , Humanos , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X , Resultado do Tratamento
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