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Synthesis, chemical, theoretical studies, electrochemical, electrical and optical characterization of novel oligomer 2,2’-((1E,1’E)(2,5-bis(octyloxy)-1,4-phenylenevinylene)bis(6-(E)-2-(vinylquinolin))quinoline for OLED applications
摘要： A fluorescent pentamer 5QnQnPV with one phenyl central donor group surrounded by four quinoline acceptor groups set in a quadrupolar A-π-A-π-D-π-A-π-A electronic structure was synthesized. This compound is an organic semiconductor and shows a wide band fluorescence emission that spans from the blue to the red region with a maximum peak centered at 509 nm. In addition, its HOMO (? 5.4 eV)/LUMO (? 3.5 eV) energy values, determined by cyclic voltammetry, optical gap EgOpt of 2.18 and theoretical DT-DFT studies indicated a potential for OLED fabrication. When such device was made with a ITO/PEDOT:PSS/5QnQnPV/Al configuration it displayed a maximum electroluminescent response at 860 nm. The structural and physical characterization of this compound was performed using 1H and 13C Nuclear Magnetic Resonance, Fourier Transformed Infrared Spectroscopy, Mass Spectroscopy and Atomic Force Microscopy.
关键词： organic semiconductor,Atomic Force Microscopy,Fourier Transformed Infrared Spectroscopy,Mass Spectroscopy,electroluminescent response,fluorescent pentamer,Nuclear Magnetic Resonance,OLED
更新于2025-09-11 14:15:04
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Understanding the Relationship Between Real-Time Thermal Imaging and Thermal Damage Estimate During Magnetic Resonance–Guided Laser Interstitial Thermal Therapy
摘要： Objectives: Magnetic Resonance-guided Laser Interstitial Thermal Therapy (MRgLITT) is a minimally invasive procedure that utilizes intraoperative magnetic resonance thermometry (MRT) to generate a thermal damage estimate (TDE) of the ablative area. This study compared areas produced by the MRT heat map to the system-generated TDE produced by the Visualase software. Methods: All ablations were performed using the Visualase MRI-Guided Laser Ablation System. MRT heat-map and TDE were quantified using MATLAB version R2014a. The TDE was compared to the summed area of the green, yellow, and red areas (HM63.9) and the summed area of the light blue, green, yellow, and red areas (HM50.4) produced by the MRT heat map. Results: 56 patients undergoing MRgLITT were examined. The mean TDE produced was 236 mm2 (SEM = 9.5). The mean HM63.9 was 231 mm2 (SEM = 8.7), and the mean HM50.4 was 370 mm2 (SEM = 12.8). There was no significant difference between the TDE and HM63.9 (p = 0.51) . There was a significant difference between TDE and HM50.4 (p < 0.001) and between HM63.9 and HM50.4 (p < 0.001). Conclusions: The system-generated TDE consistently remains contained within the boundaries of the MRT heat map. At standard factory settings, the TDE and the area produced within the periphery of the HM63.9 are similar in magnitude. The light blue portion of the MRT heat map may serve as an additional means of predicting when critical structures may be at risk during laser ablation if exposed to further thermal stress.
关键词： MRTI,Thermal ablation parameters,LITT,Laser interstitial thermal therapy,Magnetic resonance thermometry
更新于2025-09-11 14:15:04
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Laser interstitial thermal therapy in drug-resistant epilepsy
摘要： MRI-guided stereotactic laser interstitial thermal therapy (LiTT) has been utilized in the surgical treatment of discrete, small epileptogenic lesions. This review summarizes the current literature and addresses the clinical application of this technique. LiTT has the potential to reduce the morbidity and discomfort of epilepsy surgery. Review of data from retrospective, uncontrolled studies suggests that LiTT may offer benefit when treating drug-resistant epilepsy because of mesial temporal sclerosis, hypothalamic hamartoma, cavernous hemangioma, and small cortical dysplasias and malformations. It is now being offered as initial therapy in place of anterior temporal lobectomy in many centers, and a prospective study is underway to compare it with historical temporal lobectomy reports. LiTT appears promising and has potential for reduced morbidity and improved tolerability compared with open surgery. Studies must be done to compare efficacy and safety of LiTT with open surgery, and further investigation is needed to optimize this technique.
关键词： magnetic resonance-guided laser interstitial thermal therapy,epilepsy surgery,laser ablation,temporal lobe epilepsy,drug-resistant epilepsy
更新于2025-09-11 14:15:04
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Reference-Based Integral MR-EPT:Simulation and Experiment Studies on the 9.4T MRI
摘要： Current integral-equation (IE) based MR electrical properties tomography (EPT) methods utilize simulated incident radio-frequency (RF) fields, which are inaccurate and lead to reconstruction errors. To improve the accuracy and practicability of IE-based MR-EPT methods, a new approach is presented that obtains the incident fields using reference subjects and RF field mapping techniques. The Incident field approximation (IFA) is first demonstrated in this paper. This approximation assumes that two imaged subjects with similar coil/subject interactions will have similar incident RF fields, thus one can feed the estimation of the incident fields within the imaged subject into the calculation of those within a homogeneous subject (reference subject). This is done by measuring the total RF fields (??1+) of the reference using field mapping techniques, using the known EPs of the reference subject and by rearranging Ampere’s Law and the integral equations. The calculated incident RF fields are then used to reconstruct the EPs’ distribution with a three-dimensional (3D) integral-based MR-EPT method. Numerical simulation results indicated that the incident RF fields obtained from the reference subject provide accurate 3D reconstruction of EPs with less than 16% root mean square error (RMSE) in noise-free scenario while the conventional IE method had more than 28% RMSE. The phantom-based experiments at 9.4T MRI system have also been conducted to evaluate the performance of the proposed method and the results indicated that the proposed method achieved desirable robustness against the noise in practical scenario with less than 21% RMSE while the conventional differential equation-based method showed worse than 37% RMSE.
关键词： specific absorption rate,magnetic resonance imaging,integral equation,Electrical property tomography
更新于2025-09-11 14:15:04
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Application of fused image in detecting abnormalities of temporomandibular joint
摘要： Objectives: To present a method for image fusion of cone-beam computed tomography (CBCT)/computed tomography (CT) and magnetic resonance imaging (MRI) and to explore whether the image data sets fused in such a way could aid the detection of temporomandibular joint (TMJ) anatomical structures and lesions. Methods: There were five cases included in this study. One case was space occupying lesion giant cell tumor of tendon sheaths (GCTTS), one case was chronic inflammation in the condyle, one case was articular disc calcification of the bilateral TMJs, and the other two cases were temporomandibular joint disorders (anterior disc displacement without reduction). The digital imaging and communications in medicine (DICOM) format data of CT/CBCT and MRI of the cases were collected, and then imported to the Amira visual software where the registration process was conducted. Based on the different scan model, the registration process could be separated into automatic registration of CT/CBCT with quadrature slice MR images and the semi-automatic registration of CT/CBCT with oblique slice MR images by altering the registration parameters. Rigid transform model and the similarity metric of normalization mutual information (NMI) was used for registration in the present study. Results: The relationship between the soft mass and hard tissue was shown clearly in the fused images when compared to sole observation of CBCT/CT or MR images. The fused images could define the tumor outline and the destructive bone clearly in the same image. The fused results helped the observers to ensure uncertain defects which could not be confirmed only by one image data set. Conclusions: The CT/CBCT and MR images could be fused to aid detection of TMJ anatomical structures and related lesions.
关键词： multi-detector computed tomography,magnetic resonance imaging,diagnosis,cone-beam computed tomography,temporomandibular joint
更新于2025-09-11 14:15:04
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Simultaneous 18F-fluciclovine Positron Emission Tomography and Magnetic Resonance Spectroscopic Imaging of Prostate Cancer
摘要： Purpose: To investigate the associations of metabolite levels derived from magnetic resonance spectroscopic imaging (MRSI) and 18F-?uciclovine positron emission tomography (PET) with prostate tissue characteristics. In a cohort of 19 high-risk prostate cancer patients that underwent simultaneous PET/MRI, we evaluated the diagnostic performance of MRSI and PET for discrimination of aggressive cancer lesions from healthy tissue and benign lesions. Data analysis comprised calculations of correlations of mean standardized uptake values (SUVmean), maximum SUV (SUVmax), and the MRSI-derived ratio of (total choline + spermine + creatine) to citrate (CSC/C). Whole-mount histopathology was used as gold standard. Results: The results showed a moderate signi?cant correlation between both SUVmean and SUVmax with CSC/C ratio. Conclusions: We demonstrated that the simultaneous acquisition of 18F-?uciclovine PET and MRSI with an integrated PET/MRI system is feasible and a combination of these imaging modalities has potential to improve the diagnostic sensitivity and speci?city of prostate cancer lesions.
关键词： citrate,benign prostatic hyperplasia,chemical shift imaging,prostate cancer,positron emission tomography,magnetic resonance spectroscopy
更新于2025-09-11 14:15:04
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Analysis of the Methods of Discrete and Smooth Frequency Tuning in Gyrotrons for Spectroscopy, on the Example of a Generator Operated in the 0.20–0.27 THz Frequency Range
摘要： We consider the main features of a low-power frequency-tunable gyrotron with an oversized cavity, which is designed for the purposes of nuclear magnetic resonance spectroscopy and other applications and operates in the 0.20–0.27 frequency range producing an output power of 200 W. We study the possibilities of wideband output frequency tuning by exciting a sequence of modes with similar caustics using magnetic-?eld variations and smooth tuning due to the excitation of modes with a great number of longitudinal variations. Aiming at widening the frequency tuning range, we also analyzed the possibility of smooth frequency tuning determined by controlled variations of the cavity temperature. Speci?c features of the electron-optical system of such a gyrotron is discussed, along with the possibility of increasing its e?ciency by means of single-stage recovery of the residual energy of the electron beam.
关键词： gyrotron,frequency tuning,nuclear magnetic resonance spectroscopy,electron-optical system,efficiency
更新于2025-09-10 09:29:36
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Imaging the Microstructure of the Human Fetal Heart
摘要： Almost 50 years have elapsed since the seminal anatomic studies of Streeter et al1 showed that the fibers of the myocardium are arranged in a crossing helical pattern. During this time, numerous ex vivo studies of myocardial fiber architecture have been performed with magnetic resonance diffusion tensor imaging (DTI). In addition, recent advances in gradient strength and acceleration techniques now allow DTI of the entire heart to be performed in vivo.2,3 DTI also allows microstructural information to be integrated with magnetic resonance–derived metrics of myocardial strain, function, and viability.4–6
关键词： myocardium,magnetic resonance imaging,heart defects, congenital,heart,diffusion tensor imaging,Editorial
更新于2025-09-10 09:29:36
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Nitroxide-radicals–modified gold nanorods for in vivo CT/MRI-guided photothermal cancer therapy
摘要： This article presents a report of the synthesis, characterization, and biomedical application of nitroxide-radicals–modified gold nanorods (Au-TEMPO NRs) for imaging-guided photothermal cancer therapy. Patients and methods: Au nanorods were synthesized through seed-mediated growth method, 4-Amino-TEMPO was added and the reaction proceeded under magnetic stirring. Results: With a mean length of 39.2 nm and an average aspect ratio of approximately 3.85, Au-TEMPO NRs showed good photothermal ability when they were irradiated by 808-nm laser. Au-TEMPO NRs could be stored in PBS for more than 1 month, showed no cytotoxicity against both tumor and normal cells at a concentration of up to 3 mg/mL, and functioned as a dual-mode contrast agent for CT/magnetic resonance (MR) imaging in vitro and in vivo, due to their high X-ray attenuation of Au and good r1 relaxivity of nitroxide radicals. Further, they had a long retention time (~4 hours) in the main organs, which enabled a long CT/MR imaging time window for diagnosis. Bio-distribution results revealed that these Au-TEMPO NRs passively aggregated in the liver and spleen. After irradiation by 808-nm laser, Au-TEMPO NRs could ablate the solid tumor in 4T1 tumor-bearing mice, which implied they were a potential theranostic agent for dual-mode imaging and photothermal cancer therapy. Conclusion: This type of Au-TEMPO NRs with the abilities of CT/MR imaging and photothermal therapy, can play an active role in imaging-guided photothermal cancer therapy.
关键词： TEMPO,magnetic resonance imaging,PTT,Au NRs,computed tomography
更新于2025-09-10 09:29:36
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Aberrant visual pathway development in albinism: From retina to cortex
摘要： Albinism refers to a group of genetic abnormalities in melanogenesis that are associated neuronal misrouting through the optic chiasm. We perform quantitative assessment of visual pathway structure and function in 23 persons with albinism (PWA) and 20 matched controls using optical coherence tomography (OCT), volumetric magnetic resonance imaging (MRI), diffusion tensor imaging and visual evoked potentials (VEP). PWA had a higher streamline decussation index (percentage of total tractography streamlines decussating at the chiasm) compared with controls (Z = ?2.24, p = .025), and streamline decussation index correlated weakly with inter-hemispheric asymmetry measured using VEP (r = .484, p = .042). For PWA, a significant correlation was found between foveal development index and total number of streamlines (r = .662, p < .001). Significant positive correlations were found between peri-papillary retinal nerve fibre layer thickness and optic nerve (r = .642, p < .001) and tract (r = .663, p < .001) width. Occipital pole cortical thickness was 6.88% higher (Z = ?4.10, p < .001) in PWA and was related to anterior visual pathway structures including foveal retinal pigment epithelium complex thickness (r = ?.579, p = .005), optic disc (r = .478, p = .021) and rim areas (r = .597, p = .003). We were unable to demonstrate a significant relationship between OCT-derived foveal or optic nerve measures and MRI-derived chiasm size or streamline decussation index. Our novel tractographic demonstration of altered chiasmatic decussation in PWA corresponds to VEP measured cortical asymmetry and is consistent with chiasmatic misrouting in albinism. We also demonstrate a significant relationship between retinal pigment epithelium and visual cortex thickness indicating that retinal pigmentation defects in albinism lead to downstream structural reorganisation of the visual cortex.
关键词： magnetic resonance imaging,visual pathway,diffusion tensor imaging,albinism,optical coherence tomography
更新于2025-09-10 09:29:36