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1.
Eur Radiol ; 2022 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-35201408

RESUMO

OBJECTIVES: To examine the role of ADC threshold on agreement across observers and deep learning models (DLMs) plus segmentation performance of DLMs for acute ischemic stroke (AIS). METHODS: Twelve DLMs, which were trained on DWI-ADC-ADC combination from 76 patients with AIS using 6 different ADC thresholds with ground truth manually contoured by 2 observers, were tested by additional 67 patients in the same hospital and another 78 patients in another hospital. Agreement between observers and DLMs were evaluated by Bland-Altman plot and intraclass correlation coefficient (ICC). The similarity between ground truth (GT) defined by observers and between automatic segmentation performed by DLMs was evaluated by Dice similarity coefficient (DSC). Group comparison was performed using the Mann-Whitney U test. The relationship between the DSC and ADC threshold as well as AIS lesion size was evaluated by linear regression analysis. A p < .05 was considered statistically significant. RESULTS: Excellent interobserver agreement and intraobserver repeatability in the manual segmentation (all ICC > 0.98, p < .001) were achieved. The 95% limit of agreement was reduced from 11.23 cm2 for GT on DWI to 0.59 cm2 for prediction at an ADC threshold of 0.6 × 10-3 mm2/s combined with DWI. The segmentation performance of DLMs was improved with an overall DSC from 0.738 ± 0.214 on DWI to 0.971 ± 0.021 on an ADC threshold of 0.6 × 10-3 mm2/s combined with DWI. CONCLUSIONS: Combining an ADC threshold of 0.6 × 10-3 mm2/s with DWI reduces interobserver and inter-DLM difference and achieves best segmentation performance of AIS lesions using DLMs. KEY POINTS: • Higher Dice similarity coefficient (DSC) in predicting acute ischemic stroke lesions was achieved by ADC thresholds combined with DWI than by DWI alone (all p < .05). • DSC had a negative association with the ADC threshold in most sizes, both hospitals, and both observers (most p < .05) and a positive association with the stroke size in all ADC thresholds, both hospitals, and both observers (all p < .001). • An ADC threshold of 0.6 × 10-3 mm2/s eliminated the difference of DSC at any stroke size between observers or between hospitals (p = .07 to > .99).

2.
NMR Biomed ; 35(3): e4642, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34738671

RESUMO

In this study, the performance of machine learning in classifying parotid gland tumors based on diffusion-related features obtained from the parotid gland tumor, the peritumor parotid gland, and the contralateral parotid gland was evaluated. Seventy-eight patients participated in this study and underwent magnetic resonance diffusion-weighted imaging. Three regions of interest, including the parotid gland tumor, the peritumor parotid gland, and the contralateral parotid gland, were manually contoured for 92 tumors, including 20 malignant tumors (MTs), 42 Warthin tumors (WTs), and 30 pleomorphic adenomas (PMAs). We recorded multiple apparent diffusion coefficient (ADC) features and applied a machine-learning method with the features to classify the three types of tumors. With only mean ADC of tumors, the area under the curve of the classification model was 0.63, 0.85, and 0.87 for MTs, WTs, and PMAs, respectively. The performance metrics were improved to 0.81, 0.89, and 0.92, respectively, with multiple features. Apart from the ADC features of parotid gland tumor, the features of the peritumor and contralateral parotid glands proved advantageous for tumor classification. Combining machine learning and multiple features provides excellent discrimination of tumor types and can be a practical tool in the clinical diagnosis of parotid gland tumors.


Assuntos
Imagem de Difusão por Ressonância Magnética/métodos , Aprendizado de Máquina , Neoplasias Parotídeas/diagnóstico por imagem , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
3.
J Magn Reson Imaging ; 55(1): 126-137, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34169600

RESUMO

BACKGROUND: Single-shot diffusion-weighted imaging (ssDWI) has been shown useful for detecting active bowel inflammation in Crohn's disease (CD) without MRI contrast. However, ssDWI suffers from geometric distortion and low spatial resolution. PURPOSE: To compare conventional ssDWI with higher-resolution ssDWI (HR-ssDWI) and multi-shot DWI based on multiplexed sensitivity encoding (MUSE-DWI) for evaluating bowel inflammation in CD, using contrast-enhanced MR imaging (CE-MRI) as the reference standard. STUDY TYPE: Prospective. SUBJECTS: Eighty nine patients with histological diagnosis of CD from previous endoscopy (55 male/34 female, age: 17-69 years). FIELD STRENGTH/SEQUENCES: ssDWI (2.7 mm × 2.7 mm), HR-ssDWI (1.8 mm × 1.8 mm), MUSE-DWI (1.8 mm × 1.8 mm) based on echo-planar imaging, T2-weighted imaging, and CE-MRI sequences, all at 1.5 T. ASSESSMENT: Five raters independently evaluated the tissue texture conspicuity, geometry accuracy, minimization of artifacts, diagnostic confidence, and overall image quality using 5-point Likert scales. The diagnostic performance (sensitivity, specificity and accuracy) of each DWI sequences was assessed on per-bowel-segment basis. STATISTICAL TESTS: Inter-rater agreement for qualitative evaluation of each parameter was measured by the intra-class correlation coefficient (ICC). Paired Wilcoxon signed-rank tests were performed to evaluate the statistical significance of differences in qualitative scoring between DWI sequences. A P value <0.05 was considered to be statistically significant. RESULTS: Tissue texture conspicuity, geometric distortions, and overall image quality were significantly better for MUSE-DWI than for ssDWI and HR-ssDWI with good agreement among five raters (ICC: 0.70-0.89). HR-ssDWI showed significantly poorer performance to ssDWI and MUSE-DWI for all qualitative scores and had the worst diagnostic performance (sensitivity of 57.0% and accuracy of 87.3%, with 36 undiagnosable cases due to severe artifacts). MUSE-DWI showed significantly higher sensitivity (97.5% vs. 86.1%) and accuracy (98.9% vs. 95.1%) than ssDWI for detecting bowel inflammation. DATA CONCLUSION: MUSE-DWI was advantageous in assessing bowel inflammation in CD, resulting in improved spatial resolution and image quality. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2.


Assuntos
Doença de Crohn , Adolescente , Adulto , Idoso , Doença de Crohn/diagnóstico por imagem , Imagem de Difusão por Ressonância Magnética , Feminino , Humanos , Inflamação/diagnóstico por imagem , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto Jovem
5.
Sci Rep ; 11(1): 2920, 2021 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-33536471

RESUMO

The purpose of this study was to investigate the influence of arterial input function (AIF) selection on the quantification of vertebral perfusion using axial dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). In this study, axial DCE-MRI was performed on 2 vertebrae in each of eight healthy volunteers (mean age, 36.9 years; 5 men) using a 1.5-T scanner. The pharmacokinetic parameters Ktrans, ve, and vp, derived using a Tofts model on axial DCE-MRI of the lumbar vertebrae, were evaluated using various AIFs: the population-based aortic AIF (AIF_PA), a patient-specific aortic AIF (AIF_A) and a patient-specific segmental arterial AIF (AIF_SA). Additionally, peaks and delay times were changed to simulate the effects of various AIFs on the calculation of perfusion parameters. Nonparametric analyses including the Wilcoxon signed rank test and the Kruskal-Wallis test with a Dunn-Bonferroni post hoc analysis were performed. In simulation, Ktrans and ve increased as the peak in the AIF decreased, but vp increased when delay time in the AIF increased. In humans, the estimated Ktrans and ve were significantly smaller using AIF_A compared to AIF_SA no matter the computation style (pixel-wise or region-of-interest based). Both these perfusion parameters were significantly greater using AIF_SA compared to AIF_A.


Assuntos
Vértebras Lombares/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Imagem de Perfusão/métodos , Adulto , Feminino , Voluntários Saudáveis , Humanos , Interpretação de Imagem Assistida por Computador , Vértebras Lombares/irrigação sanguínea , Masculino , Pessoa de Meia-Idade , Adulto Jovem
6.
NMR Biomed ; 34(1): e4408, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32886955

RESUMO

Various MRI sequences have shown their potential to discriminate parotid gland tumors, including but not limited to T2 -weighted, postcontrast T1 -weighted, and diffusion-weighted images. In this study, we present a fully automatic system for the diagnosis of parotid gland tumors by using deep learning methods trained on multimodal MRI images. We used a two-dimensional convolution neural network, U-Net, to segment and classify parotid gland tumors. The U-Net model was trained with transfer learning, and a specific design of the batch distribution optimized the model accuracy. We also selected five combinations of MRI contrasts as the input data of the neural network and compared the classification accuracy of parotid gland tumors. The results indicated that the deep learning model with diffusion-related parameters performed better than those with structural MR images. The performance results (n = 85) of the diffusion-based model were as follows: accuracy of 0.81, 0.76, and 0.71, sensitivity of 0.83, 0.63, and 0.33, and specificity of 0.80, 0.84, and 0.87 for Warthin tumors, pleomorphic adenomas, and malignant tumors, respectively. Combining diffusion-weighted and contrast-enhanced T1 -weighted images did not improve the prediction accuracy. In summary, the proposed deep learning model could classify Warthin tumor and pleomorphic adenoma tumor but not malignant tumor.


Assuntos
Aprendizado Profundo , Imageamento por Ressonância Magnética , Glândula Parótida/diagnóstico por imagem , Glândula Parótida/patologia , Neoplasias Parotídeas/classificação , Neoplasias Parotídeas/diagnóstico por imagem , Imagem de Difusão por Ressonância Magnética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Imagem Multimodal
7.
NMR Biomed ; 33(5): e4282, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32124504

RESUMO

The aim of this study was to evaluate the imaging quality and diagnostic performance of fast spin echo diffusion-weighted imaging with periodically rotated overlapping parallel lines with enhanced reconstruction (FSE-PROP-DWI) in distinguishing parotid pleomorphic adenoma (PMA) from Warthin tumor (WT). This retrospective study enrolled 44 parotid gland tumors from 34 patients, including 15 PMAs and 29 WTs with waived written informed consent. All participants underwent 1.5 T diffusion-weighted imaging including FSE-PROP-DWI and single-shot echo-planar diffusion-weighted imaging (SS-EP-DWI). After imaging resizing and registration among T2WI, FSE-PROP-DWI and SS-EP-DWI, imaging distortion was quantitatively analyzed by using the Dice coefficient. Signal-to-noise ratio and contrast-to-noise ratio were qualitatively evaluated. The mean apparent diffusion coefficient (ADC) of parotid gland tumors was calculated. Wilcoxon signed-rank test was used for paired comparison between FSE-PROP-DWI versus SS-EP-DWI. Mann-Whitney U test was used for independent group comparison between PMAs versus WTs. Diagnostic performance was evaluated by receiver operating characteristics curve analysis. P < 0.05 was considered statistically significant. The Dice coefficient was statistically significantly higher on FSE-PROP-DWI than SS-EP-DWI for both tumors (P < 0.005). Mean ADC was statistically significantly higher in PMAs than WTs on both FSE-PROP-DWI and SS-EP-DWI (P < 0.005). FSE-PROP-DWI and SS-EP-DWI successfully distinguished PMAs from WTs with an AUC of 0.880 and 0.945, respectively (P < 0.05). Sensitivity, specificity, positive predictive value, negative predictive value and accuracy in diagnosing PMAs were 100%, 69.0%, 62.5%, 100% and 79.5% for FSE-PROP-DWI, and 100%, 82.8%, 75%, 100% and 88.6% for SS-EP-DWI, respectively. FSE-PROP-DWI is useful to distinguish parotid PMAs from WTs with less distortion of tumors but lower AUC than SS-EP-DWI.


Assuntos
Adenolinfoma/diagnóstico por imagem , Adenolinfoma/diagnóstico , Adenoma Pleomorfo/diagnóstico por imagem , Adenoma Pleomorfo/diagnóstico , Imagem de Difusão por Ressonância Magnética , Neoplasias Parotídeas/diagnóstico por imagem , Neoplasias Parotídeas/diagnóstico , Neoplasias das Glândulas Salivares/diagnóstico por imagem , Neoplasias das Glândulas Salivares/diagnóstico , Diagnóstico Diferencial , Humanos , Processamento de Imagem Assistida por Computador , Curva ROC , Processamento de Sinais Assistido por Computador , Razão Sinal-Ruído
8.
J Magn Reson Imaging ; 51(5): 1382-1389, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31625643

RESUMO

BACKGROUND: Adipose tissue is closely related to bone mass, bone quality, and bone fractures, but the connection between fat and bone is complex and gender-related. Fat-water magnetic resonance imaging (MRI) and MR spectroscopy (MRS) are very useful tools for identifying tissue fat. PURPOSE: To assess gender interactions between bone mineral density (BMD), bone marrow fat, and body mass index (BMI) in the elderly using fat-water MRI and MRS. STUDY TYPE: Prospective/cohort. POPULATION: Sixty-six women and 38 men (mean age, 62.3 years; range, 50-75 years), Asian. FIELD STRENGTH: A 1.5T MR equipped with a body and spine array coil. STEAM MRS and T2 * Dixon were performed. ASSESSMENT: Vertebral bone marrow fat ratio (MFR), BMI, and BMD were measured. Correlations between these variables and differences in bone density in MFR were assessed between participants, divided into three groups based on bone density. STATISTICAL TESTS: Multiple regression; Pearson tests; analysis of covariance; analysis of variance. RESULTS: Multiple regression analysis identified gender, vertebral bone MFR, and BMI as significant predictors of vertebral BMD (P < 0.001). Among the women, vertebral BMD was negatively correlated with vertebral MFR (P = 0.011), but among the men, it was positively correlated with BMI (P = 0.048), although this relationship was confounded by age and MFR. Moreover, vertebral bone marrow fat and BMI were indeed statistically uncorrelated in the elderly (P = 0.357 in women; P = 0.961 in men). DATA CONCLUSION: We found gender interactions between fat and bone in the elderly. Higher bone marrow fat was correlated with lower trabecular BMD in older women but not in men. On the other hand, the positive correlation between BMI and BMD was more pronounced in men than in women. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:1382-1389.


Assuntos
Densidade Óssea , Água , Tecido Adiposo/diagnóstico por imagem , Idoso , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Coluna Vertebral
9.
Nanoscale Res Lett ; 13(1): 109, 2018 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-29675727

RESUMO

In this study, alpha nickel sulfide (α-NiS) nanosphere films have been successfully synthesized by electroplating the nickel nanosheet film on the indium tin oxide (ITO) glass substrate and sulfuring nickel-coated ITO glass substrate. First, we electrodeposited the nickel nanosheet films on the ITO glass substrates which were cut into a 0.5 × 1 cm2 size. Second, the nanosheet nickel films were annealed in vacuum-sealed glass ampoules with sulfur sheets at different annealing temperatures (300, 400, and 500 °C) for 4 h in vacuum-sealed glass ampoules. The α-NiS films were investigated by using X-ray diffraction (XRD), variable vacuum scanning electron microscopy (VVSEM), field emission scanning electron microscopy/energy dispersive spectrometer (FE-SEM/EDS), cyclic voltammogram (CV), electrochemical impedance spectroscopy (EIS), ultraviolet/visible/near-infrared (UV/Visible/NIR) spectra, and photoluminescence (PL) spectra. Many nanospheres were observed on the surface of the α-NiS films at the annealing temperature 400 °C for 4 h. We also used the high-resolution transmission electron microscopy (HR-TEM) for the analysis of the α-NiS nanospheres. We demonstrated that our α-NiS nanosphere film had a linear current response to different glucose concentrations. Additionally, our α-NiS nanosphere films were preserved at room temperature for five and a half years and were still useful for detecting glucose at low concentration.

10.
Surg Today ; 48(7): 680-686, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29516276

RESUMO

PURPOSE: Laparoscopic distal pancreatectomy has proven to be feasible and safe. Moreover, robotic surgery provides unique advantages for pancreatic procedures, although single-incision robotic pancreatic surgery is rarely discussed. We applied the single-port modified platform to accomplish robotic distal pancreatectomy in a series of patients. METHODS: The subjects of this study were ten patients who underwent robotic distal pancreatectomy in our hospital between July 1, 2015 and Dec 31, 2016. All patients were placed supine in the reverse Trendelenburg position with the legs abducted. Surgery was performed via a trans-umbilical 5.0-cm incision, using a modified single-port platform (LAGIPORT®) combined with the da Vinci Si Surgical System. The three arms and scope (30-degree up) were inserted through the LAGIPORT® and positioned in a triangle. Endoscopic ultrasound was used to localize the tumor and plan the resection margin. We recorded the surgical time, operation time, blood loss, postoperative pain score, hospital stay, and complications. RESULTS: The surgical time was 236 ± 32 min, the operation time was 172 ± 30 min, and the blood loss was 149 ± 65 ml. All patients underwent robot-assisted distal pancreatectomy without conversion. The average pain score on postoperative day (POD) 3 was 4.5 ± 1. Complications included subsplenic hematoma (n = 1) and minor pancreatic leakage (n = 2). There was no surgical mortality. CONCLUSIONS: Our results demonstrate the safety and efficiency of robotic single-incision distal pancreatectomy via the modified platform (LAGIPORT®).


Assuntos
Pancreatectomia/instrumentação , Neoplasias Pancreáticas/cirurgia , Procedimentos Cirúrgicos Robóticos/instrumentação , Adulto , Idoso , Fístula Anastomótica/epidemiologia , Perda Sanguínea Cirúrgica/estatística & dados numéricos , Feminino , Hematoma/epidemiologia , Humanos , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Duração da Cirurgia , Dor Pós-Operatória/epidemiologia , Pancreatectomia/métodos , Complicações Pós-Operatórias/epidemiologia , Procedimentos Cirúrgicos Robóticos/métodos , Segurança , Esplenopatias/epidemiologia , Decúbito Dorsal , Resultado do Tratamento
11.
NMR Biomed ; 31(3)2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29315960

RESUMO

The aim of this study was to investigate proton changes of the parotid gland after gustatory stimulation by semi-quantitative parameters and an empirical mathematical model (EMM) using high-temporal-resolution, double-echo, echo-planar imaging (EPI). Approved by a local institutional review board, this study examined 20 parotid glands from 10 healthy volunteers (male:female = 6: 4; age ± standard deviation =35.1 ± 14.1 years) with written informed consent obtained. All participants underwent 1.5-T, double-echo EPI with gustatory stimulation. Semi-quantitative parameters, including maximal drop ratio (MDR), time to peak (TTP), drop slope (DS), recovery slope (RS) and recovery ratio (RR), were calculated. The effect of temporal resolution on parotid functional parameters was evaluated. An EMM comprising an output function ( Sot=Aoe-kot+B) and an input function ( Sint=Ain1-e-kint) was also applied to fit all dynamic curves. Kruskal-Wallis test, Wilcoxon test, linear regression analysis and goodness of fit were used for statistical analysis. p < 0.05 was considered to be statistically significant. The signal intensity dropped significantly after gustatory stimulation on the proton density (PD) image (p < 0.01). MDR was 8.26% in the PD image. MDR and RR were negatively associated with time interval, whereas DS and TTP were significantly positively associated with time interval (all p < 0.05). EMM parametric values derived from PD-time curves of parotid glands were 12.04 ± 6.81%, 6.43 ± 4.23 min-1 , 88.73 ± 6.18%, 8.41 ± 4.86 min-1 and 1.09 ± 1.35 for Ao , ko , B, Ain and kin , respectively. Semi-quantitative functional parameters and EMM parameters using high-temporal-resolution, double-echo EPI allow the quantification of parotid proton changes after gustatory stimulation.


Assuntos
Imageamento por Ressonância Magnética , Glândula Parótida/metabolismo , Prótons , Paladar , Adulto , Simulação por Computador , Feminino , Humanos , Masculino , Fatores de Tempo
12.
Int J Mol Sci ; 18(6)2017 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-28561778

RESUMO

Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, catalyzes tri-methylation of histone H3 at Lys 27 (H3K27me3) to regulate gene expression through epigenetic machinery. EZH2 functions as a double-facet molecule in regulation of gene expression via repression or activation mechanisms, depending on the different cellular contexts. EZH2 interacts with both histone and non-histone proteins to modulate diverse physiological functions including cancer progression and malignancy. In this review article, we focused on the updated information regarding microRNAs (miRNAs) and long non coding RNAs (lncRNAs) in regulation of EZH2, the oncogenic and tumor suppressive roles of EZH2 in cancer progression and malignancy, as well as current pre-clinical and clinical trials of EZH2 inhibitors.


Assuntos
Proteína Potenciadora do Homólogo 2 de Zeste/genética , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Neoplasias/genética , RNA Longo não Codificante/genética , Progressão da Doença , Proteína Potenciadora do Homólogo 2 de Zeste/antagonistas & inibidores , Inibidores Enzimáticos/uso terapêutico , Humanos , Mutação , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Proteínas Supressoras de Tumor/genética
13.
Sci Rep ; 6: 25206, 2016 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-27143609

RESUMO

Diagnosis of osteoporosis is based on bone mineral density (BMD) measurement, which is site dependent and commonly discordant between measurement sites. We aimed to determine the prevalence of osteoporosis diagnosed based on BMD T-scores measured by dual-energy x-ray absorptiometry (DXA) at different sites: the lumbar spine (LS) alone, femoral neck (FN) alone, or both. A total of 1712 women and 2028 men with LS and FN BMD measurements were enrolled. Over 50% discordance was found between osteoporosis classifications based on T-scores measured at the LS and FN. Use of the lowest T-scores measured at both the LS and right and left FN (rather than one site) significantly increased the prevalence of osteoporosis from 4.03 to 10.75% in postmenopausal women and 1.82 to 4.29% in men aged ≧50 years (p < 0.001). The trends of overall and age-adjusted prevalence of osteoporosis were similar in women and men. Osteoporosis was diagnosed at a higher rate if the USA reference rather than the Asia reference was used to calculate the T-score (26.64% vs. 10.75%). In conclusion, diagnosis based on the lowest T-score from multiple site BMD measurement can increase the prevalence of osteoporosis, demonstrating the higher sensitivity of the multiple site measurement strategy.


Assuntos
Osteoporose/epidemiologia , Absorciometria de Fóton , Idoso , Idoso de 80 Anos ou mais , Densidade Óssea , Feminino , Colo do Fêmur/diagnóstico por imagem , Colo do Fêmur/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Osteoporose/diagnóstico por imagem , Prevalência , Coluna Vertebral/diagnóstico por imagem , Coluna Vertebral/patologia
14.
Med Phys ; 43(4): 1873, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27036583

RESUMO

PURPOSE: To verify whether quantification of parotid perfusion is affected by fat signals on non-fat-saturated (NFS) dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and whether the influence of fat is reduced with fat saturation (FS). METHODS: This study consisted of three parts. First, a retrospective study analyzed DCE-MRI data previously acquired on different patients using NFS (n = 18) or FS (n = 18) scans. Second, a phantom study simulated the signal enhancements in the presence of gadolinium contrast agent at six concentrations and three fat contents. Finally, a prospective study recruited nine healthy volunteers to investigate the influence of fat suppression on perfusion quantification on the same subjects. Parotid perfusion parameters were derived from NFS and FS DCE-MRI data using both pharmacokinetic model analysis and semiquantitative parametric analysis. T tests and linear regression analysis were used for statistical analysis with correction for multiple comparisons. RESULTS: NFS scans showed lower amplitude-related parameters, including parameter A, peak enhancement (PE), and slope than FS scans in the patients (all with P < 0.0167). The relative signal enhancement in the phantoms was proportional to the dose of contrast agent and was lower in NFS scans than in FS scans. The volunteer study showed lower parameter A (6.75 ± 2.38 a.u.), PE (42.12% ± 14.87%), and slope (1.43% ± 0.54% s(-1)) in NFS scans as compared to 17.63 ± 8.56 a.u., 104.22% ± 25.15%, and 9.68% ± 1.67% s(-1), respectively, in FS scans (all with P < 0.005). These amplitude-related parameters were negatively associated with the fat content in NFS scans only (all with P < 0.05). CONCLUSIONS: On NFS DCE-MRI, quantification of parotid perfusion is adversely affected by the presence of fat signals for all amplitude-related parameters. The influence could be reduced on FS scans.


Assuntos
Imageamento por Ressonância Magnética/métodos , Glândula Parótida/irrigação sanguínea , Glândula Parótida/diagnóstico por imagem , Fluxo Sanguíneo Regional , Adulto , Idoso , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas , Adulto Jovem
15.
PLoS One ; 10(8): e0137073, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26323091

RESUMO

PURPOSE: To concurrently quantify the radiation-induced changes and temporal evolutions of parotid volume and parotid apparent diffusion coefficient (ADC) in nasopharyngeal carcinoma (NPC) patients treated by intensity-modulated radiotherapy by using magnetic resonance imaging (MRI). MATERIALS AND METHODS: A total of 11 NPC patients (9 men and 2 women; 48.7 ± 11.7 years, 22 parotid glands) were enrolled. Radiation dose, parotid sparing volume, severity of xerostomia, and radiation-to-MR interval (RMI) was recorded. MRI studies were acquired four times, including one before and three after radiotherapy. The parotid volume and the parotid ADC were measured. Statistical analysis was performed using SPSS and MedCalc. Bonferroni correction was applied for multiple comparisons. A P value less than 0.05 was considered as statistically significant. RESULTS: The parotid volume was 26.2 ± 8.0 cm(3) before radiotherapy. The parotid ADC was 0.8 ± 0.15 × 10(-3) mm(2)/sec before radiotherapy. The parotid glands received a radiation dose of 28.7 ± 4.1 Gy and a PSV of 44.1 ± 12.6%. The parotid volume was significantly smaller at MR stage 1 and stage 2 as compared to pre-RT stage (P < .005). The volume reduction ratio was 31.2 ± 13.0%, 26.1 ± 13.5%, and 17.1 ± 16.6% at stage 1, 2, and 3, respectively. The parotid ADC was significantly higher at all post-RT stages as compared to pre-RT stage reciprocally (P < .005 at stage 1 and 2, P < .05 at stage 3). The ADC increase ratio was 35.7 ± 17.4%, 27.0 ± 12.8%, and 20.2 ± 16.6% at stage 1, 2, and 3, respectively. The parotid ADC was negatively correlated to the parotid volume (R = -0.509; P < .001). The parotid ADC was positively associated with the radiation dose significantly (R(2) = 0.212; P = .0001) and was negatively associated with RMI significantly (R(2) = 0.203; P = .00096) significantly. Multiple regression analysis further showed that the post-RT parotid ADC was related to the radiation dose and RMI significantly (R(2) = 0.3580; P < .0001). At MR stage 3, the parotid volume was negatively associated with the dry mouth grade significantly (R(2) = 0.473; P < .0001), while the parotid ADC was positively associated with the dry mouth grade significantly (R(2) = 0.288; P = .015). CONCLUSION: Our pilot study successfully demonstrates the concurrent changes and temporal evolution of parotid volume and parotid ADC quantitatively in NPC patients treated by IMRT. Our results suggest that the reduction of parotid volume and increase of parotid ADC are dominated by the effect of acinar loss rather than edema at early to intermediate phases and the following recovery of parotid volume and ADC toward the baseline values might reflect the acinar regeneration of parotid glands.


Assuntos
Neoplasias Nasofaríngeas/patologia , Neoplasias Nasofaríngeas/radioterapia , Glândula Parótida/patologia , Glândula Parótida/efeitos da radiação , Carcinoma , Relação Dose-Resposta à Radiação , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Carcinoma Nasofaríngeo , Projetos Piloto , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Xerostomia/patologia , Xerostomia/radioterapia
16.
PLoS One ; 10(4): e0124118, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25922948

RESUMO

OBJECTIVES: To investigate transient signal loss on diffusion weighted images (DWI) and overestimation of apparent diffusion coefficient (ADC) in parotid glands using single shot echoplanar DWI (EPDWI). MATERIALS AND METHODS: This study enrolled 6 healthy subjects and 7 patients receiving radiotherapy. All participants received dynamic EPDWI with a total of 8 repetitions. Imaging quality of DWI was evaluated. Probability of severe overestimation of ADC (soADC), defined by an ADC ratio more than 1.2, was calculated. Error on T2WI, DWI, and ADC was computed. Statistical analysis included paired Student t testing and Mann-Whitney U test. A P value less than 0.05 was considered statistically significant. RESULTS: Transient signal loss was visually detected on some excitations of DWI but not on T2WI or mean DWI. soADC occurred randomly among 8 excitations and 3 directions of diffusion encoding gradients. Probability of soADC was significantly higher in radiotherapy group (42.86%) than in healthy group (24.39%). The mean error percentage decreased as the number of excitations increased on all images, and, it was smallest on T2WI, followed by DWI and ADC in an increasing order. CONCLUSIONS: Transient signal loss on DWI was successfully detected by dynamic EPDWI. The signal loss on DWI and overestimation of ADC could be partially remedied by increasing the number of excitations.


Assuntos
Imagem de Difusão por Ressonância Magnética , Glândula Parótida/diagnóstico por imagem , Adulto , Estudos de Casos e Controles , Imagem Ecoplanar , Feminino , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Glândula Parótida/patologia , Radiografia , Risco
17.
PLoS One ; 9(7): e102326, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25029592

RESUMO

PURPOSE: To investigate the performance of hematoma shape, hematoma size, Glasgow coma scale (GCS) score, and intracerebral hematoma (ICH) score in predicting the 30-day mortality for ICH patients. To examine the influence of the estimation error of hematoma size on the prediction of 30-day mortality. MATERIALS AND METHODS: This retrospective study, approved by a local institutional review board with written informed consent waived, recruited 106 patients diagnosed as ICH by non-enhanced computed tomography study. The hemorrhagic shape, hematoma size measured by computer-assisted volumetric analysis (CAVA) and estimated by ABC/2 formula, ICH score and GCS score was examined. The predicting performance of 30-day mortality of the aforementioned variables was evaluated. Statistical analysis was performed using Kolmogorov-Smirnov tests, paired t test, nonparametric test, linear regression analysis, and binary logistic regression. The receiver operating characteristics curves were plotted and areas under curve (AUC) were calculated for 30-day mortality. A P value less than 0.05 was considered as statistically significant. RESULTS: The overall 30-day mortality rate was 15.1% of ICH patients. The hematoma shape, hematoma size, ICH score, and GCS score all significantly predict the 30-day mortality for ICH patients, with an AUC of 0.692 (P = 0.0018), 0.715 (P = 0.0008) (by ABC/2) to 0.738 (P = 0.0002) (by CAVA), 0.877 (P<0.0001) (by ABC/2) to 0.882 (P<0.0001) (by CAVA), and 0.912 (P<0.0001), respectively. CONCLUSION: Our study shows that hematoma shape, hematoma size, ICH scores and GCS score all significantly predict the 30-day mortality in an increasing order of AUC. The effect of overestimation of hematoma size by ABC/2 formula in predicting the 30-day mortality could be remedied by using ICH score.


Assuntos
Hemorragia Cerebral/diagnóstico , Hemorragia Cerebral/mortalidade , Escala de Coma de Glasgow , Hematoma/patologia , Projetos de Pesquisa , Área Sob a Curva , Tomografia Computadorizada de Feixe Cônico , Humanos , Valor Preditivo dos Testes , Análise de Regressão , Estudos Retrospectivos , Estatísticas não Paramétricas
18.
Eur Radiol ; 24(9): 2069-76, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24972952

RESUMO

OBJECTIVES: To establish standard apparent diffusion coefficient (ADC) and the fat content as a function of age, gender and body mass index (BMI) in healthy parotid glands, and to address the influences of fat suppression on ADC measurements. METHODS: A total of 100 healthy adults (gender and age evenly distributed) were prospectively recruited, with parotid fat content measured from gradient-echo images with fat-water separated using iterative decomposition with echo asymmetry and least squares (IDEAL). The ADCs were estimated using both fat-saturated and non-fat-saturated diffusion-weighted imaging via a periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) technique. RESULTS: Parotid fat content was larger in men than in women by about 10 percentage points (P < 0.005), and positively associated with BMI and age for both genders (mostly with P < 0.001). ADCs estimated with non-fat-saturated PROPELLER were significantly lower in men than in women (P < 0.005), but showed no gender difference if measured using fat-saturated PROPELLER (P = 0.840). The negative association between parotid ADC and age/BMI/fat (P < 0.001) showed greater regression slopes in non-fat-saturated PROPELLER than in fat-saturated data. CONCLUSIONS: Parotid fat content in healthy adults correlates positively with both age and BMI; the correlation with age is gender-dependent. Parotid ADC measurements are strongly influenced by fat saturation. KEY POINTS: Parotid fat content in healthy adults correlates positively with age and BMI. The rate of aging-related increase in fat contents is gender-dependent. Parotid ADC measurements are strongly influenced by fat saturation.


Assuntos
Tecido Adiposo/anatomia & histologia , Índice de Massa Corporal , Imagem de Difusão por Ressonância Magnética/métodos , Imageamento Tridimensional/métodos , Glândula Parótida/anatomia & histologia , Adulto , Fatores Etários , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Valores de Referência , Fatores Sexuais
19.
Magn Reson Imaging ; 32(5): 487-90, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24629509

RESUMO

To investigate cVMR by using CO2-based hypercapnic challenge and blood flow monitoring employing non-triggered phase contrast (PC) magnetic resonance imaging. Six healthy volunteers (6 male; mean age: 29 years) participated this study after providing institutionally approved consent. This study used non-triggered PC imaging to increase temporal resolution of dynamic blood flow measurements, allowing real-time monitoring of the hypercapnic challenge response. Results suggest that vasomotor reactivity measured by non-triggered PC imaging is positively associated with the concentration of inhaled CO2. This study concludes that CO2 challenge combined with non-triggered PC flow imaging is potentially useful to provide diagnostic information for patients with cerebrovascular disease.


Assuntos
Encéfalo/fisiologia , Dióxido de Carbono/administração & dosagem , Artérias Cerebrais/fisiologia , Circulação Cerebrovascular/fisiologia , Angiografia por Ressonância Magnética/métodos , Sistema Vasomotor/fisiologia , Administração por Inalação , Adulto , Velocidade do Fluxo Sanguíneo/efeitos dos fármacos , Velocidade do Fluxo Sanguíneo/fisiologia , Encéfalo/efeitos dos fármacos , Artérias Cerebrais/efeitos dos fármacos , Meios de Contraste , Humanos , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Resistência Vascular/efeitos dos fármacos , Resistência Vascular/fisiologia , Sistema Vasomotor/efeitos dos fármacos
20.
Cell Transplant ; 23(12): 1599-612, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24480430

RESUMO

In our previous study, intracerebral implantation of peripheral blood stem cells (PBSCs) improved functional outcome in rats with chronic cerebral infarction. Based on this finding, a randomized, single blind controlled study was conducted in 30 patients [PBSC group (n = 15) and control group (n = 15)] with middle cerebral artery infarction confirmed on a T2-weighted MRI 6 months to 5 years after a stroke. Only subjects with neurological deficits of intermediate severity based on the National Institute of Health Stroke Scale (NIHSS; range: 9-20) that had been stable for at least 3 months were enrolled. Those in the PBSC group received subcutaneous G-CSF injections (15 µg/kg/day) for 5 consecutive days, and then stereotaxic implantation of 3-8 × 10(6) CD34(+) immunosorted PBSCs. All 30 patients completed the 12-month follow-up. No serious adverse events were noted during study period. Improvements in stroke scales (NIHSS, ESS, and EMS) and functional outcomes (mRS) from baseline to the end of the 12-month follow-up period were significantly greater in the PBSC than the control group. The fiber numbers asymmetry (FNA) scores based on diffusion tensor image (DTI) tractography were reduced in every PBSC-treated subject, but not in the control group. Reduction in the FNA scores correlated well with the improvement in NIHSS. Furthermore, a positive motor-evoked potential (MEP) response by transcranial magnetic stimulation (TMS) appeared in 9 of the 15 subjects in the PBSC group. This phase II study demonstrated that implantation of autologous CD34(+) PBSC was safe, feasible, and effective in improving functional outcome.


Assuntos
Transplante de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas/citologia , Acidente Vascular Cerebral/terapia , Adulto , Idoso , Demografia , Imagem de Tensor de Difusão , Potencial Evocado Motor , Feminino , Seguimentos , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Humanos , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/fisiopatologia , Fatores de Tempo , Transplante Autólogo , Resultado do Tratamento
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