Magnetic resonance imaging(MRI) can obtain multi-modal images with different contrast, which provides rich information for clinical diagnosis. However, some contrast images are not scanned or the quality of the acquired images cannot meet the diagnostic requirements due to the difficulty of patient's cooperation or the limitation of scanning conditions. Image synthesis techniques have become a method to compensate for such image deficiencies. In recent years, deep learning has been widely used in the field of MRI synthesis. In this paper, a synthesis network based on multi-modal fusion is proposed, which firstly uses a feature encoder to encode the features of multiple unimodal images separately, and then fuses the features of different modal images through a feature fusion module, and finally generates the target modal image. The similarity measure between the target image and the predicted image in the network is improved by introducing a dynamic weighted combined loss function based on the spatial domain and K-space domain. After experimental validation and quantitative comparison, the multi-modal fusion deep learning network proposed in this paper can effectively synthesize high-quality MRI fluid-attenuated inversion recovery (FLAIR) images. In summary, the method proposed in this paper can reduce MRI scanning time of the patient, as well as solve the clinical problem of missing FLAIR images or image quality that is difficult to meet diagnostic requirements.
ObjectiveTo summarize the research progress of near infra-red fluorescence imaging (NIRFI) in biliary tract surgery, and to provide protection for improvements of therapeutic effect and safety of biliary tract surgery.MethodThe relevant literatures about studies on NIRFI in the biliary tract surgery in recent years were reviewed.ResultsThe NIRFI had been preliminarily used in the surgical treatment of benign and malignant biliary diseases, and had shown its unique value in cholangiography. It provided a new method for effectively avoiding surgical complications, shortening operation time, reducing the rate of conversion to open surgery, evaluating blood supply of bile duct and improving the safety of operation.ConclusionsNIRFI has achieved notable successes in treatment of biliary tract diseases. With future application of fluorescence imaging in near infra-red Ⅱ window and new specific fluorescence targeting molecules, this technique will highlight its more important values in biliary surgery.
ObjectiveTo analyze the causes of unrelieved epilepsy thoroughly in children with isolated focal cortical dysplasia (FCD) based on MRI.MethodsRetrospective analysis of MRI and clinical data of 21 children with isolated FCD during July 2014 to January 2018, which confirmed by pathology and unrelieved thoroughly after operation performed, the pathological types and MRI signs were analyzed, as well as the frequency of different MRI signs in FCD of each pathological type. Analyzed the possible factors of surgical failure.ResultsAmong the 21 cases, there were 15 males and 6 females, with an average age of (5.7±0.3) years and an average course of disease of (3.4±0.5) years.MRI signs of this part of the children were mainly manifested by blurred focal gray matter boundaries, abnormal cortical structure changes (thickening and/or thinning), transmantle signs (abnormal cone signals extending from subcortical white matter to the ventricle) and abnormal gray matter signals, which were similar to MRI signs of FCD with satisfactory postoperative epilepsy control. 17 cases (80.9%) appeared epileptic discharge after operation in the EEG monitoring area 2 weeks to 6 months, FCD type I and type Ⅱ accounted for 35.3%, 64.7% respectively. During intraoperative EEG monitoring, no epileptiform discharge was observed in the transmantle sign region in 6 cases, and the region was retained, and only the surrounding abnormal discharge cortex was removed, complete removal of the tansmantle sign and surrounding abnormal discharge area was performed in 2 cases, and different degrees of epileptic epilepsy were observed in both methods.ConclusionMRI signs of isolated FCD with unrelieved epilepsy after operation were nonspecific, there were still epilepsy of varying degrees after all epileptogenic lesions have been removed, the cause may be related to potential epileptic factors.
Liver cancer is one of the world’s most prevalent malignancies, and is also the third leading cause of cancer death in China. Hepatitis and cirrhosis background is a major feature of liver cancer patients in China, which makes specific requirements that suits the national conditions in many aspects of prevention and control like screening diagnosis, treatment options, and prognosis follow-up. The Specifications for Diagnosis and Treatment of Primary Liver Cancer (2017 Edition), which is based on China’s practice, proposes liver cancer staging in line with China’s national conditions and forms a multi-disciplinary joint diagnosis and treatment model based on surgical treatment. Liver transplantation is included in liver cancer as one of the surgical treatments option. It also emphasizes the support of evidence-based medicine. The Specifications for Diagnosis and Treatment of Primary Liver Cancer (2017 Edition) may have laid a solid foundation for future diagnosis and treatment of liver cancer in China.
The cardiac conduction system (CCS) is a set of specialized myocardial pathways that spontaneously generate and conduct impulses transmitting throughout the heart, and causing the coordinated contractions of all parts of the heart. A comprehensive understanding of the anatomical characteristics of the CCS in the heart is the basis of studying cardiac electrophysiology and treating conduction-related diseases. It is also the key of avoiding damage to the CCS during open heart surgery. How to identify and locate the CCS has always been a hot topic in researches. Here, we review the histological imaging methods of the CCS and the specific molecular markers, as well as the exploration for localization and visualization of the CCS. We especially put emphasis on the clinical application prospects and the future development directions of non-destructive imaging technology and real-time localization methods of the CCS that have emerged in recent years.
ObjectiveTo summarize the application of magnetic resonance imaging (MRI) in the evaluation of pancreatic exocrine function.MethodIn this paper, we reviewed and summarized the related literatures about the application of MRI in the field of pancreatic exocrine function evaluation in recent years.ResultsA variety of MRI techniques could be used to detect the pancreatic exocrine function. In addition to conventional MRI techniques, there were also MRI stimulated by pancreatic secretions, cine (dynamic) cholangiopancreatography based on space selective reverse recovery pulse, and so on.ConclusionThe new MRI techniques have potential for semi-quantitative and quantitative evaluation of pancreatic exocrine function.
Objective To investigate the feasibility of imaging of bone marrow mesenchymal stem cells (BMMSCs) labeled with superparamagnetic iron oxide(SPIO) transplanted into coronary artery in vivo using magnetic resonance imaging (MRI), and the redistribution of the cells into other organs. Methods BMMSCs were isolated, cultured from bone marrow of Chinese mini swine, and double labeled with SPIO and CMDiI(Cell TrackerTM C-7001). The labeled cells were injected into left anterior descending coronary artery through a catheter. The injected cells were detected by using MRI at 1 week,3weeks after transplantation. And different organs were harvested and evaluated the redistribution of transplanted cells through pathology. Results The SPIO labeled BMMSCs injected into coronary artery could be detected through MRI and confirmed by pathology and maintained more than 3 weeks. The SPIO labeled cells could be clearly imaged as signal void lesions in the related artery. The pathology showed that the injected cells could be distributed into the area of related artery, and the cells injected into coronary artery could be found in the lung, spleen, kidney, but scarcely in the liver, the structures of these organs remained normal. Conclusion The SPIO labeled BMMSCs injected into coronary artery can be detected by using MRI, the transplanted cells can be redistributed into the non-targeted organs.
Pulsed magnetic field gradients generated by gradient coils are widely used in signal location in magnetic resonance imaging (MRI). However, gradient coils can also induce eddy currents in final magnetic field in the nearby conducting structures which lead to distortion and artifact in images, misguiding clinical diagnosis. We tried in our laboratory to measure the magnetic field of gradient-induced eddy current in 1.5 T superconducting magnetic resonance imaging device; and extracted key parameters including amplitude and time constant of exponential terms according to inductance-resistance series mathematical module. These parameters of both self-induced component and crossing component are useful to design digital filters to implement pulse pre-emphasize to reshape the waveform. A measure device that is a basement equipped with phantoms and receiving coils was designed and placed in the isocenter of the magnetic field. By applying testing sequence, contrast experiments were carried out in a superconducting magnet before and after eddy current compensation. Sets of one dimension signal were obtained as raw data to calculate gradient-induced eddy currents. Curve fitting by least squares method was also done to match inductance-resistance series module. The results also illustrated that pulse pre-emphasize measurement with digital filter was correct and effective in reducing eddy current effect. Pre-emphasize waveform was developed based on system function. The usefulness of pre-emphasize measurement in reducing eddy current was confirmed and the improvement was also presented. All these are valuable for reducing artifact in magnetic resonance imaging device.
ObjectiveThe research goal: to study the diagnostic value of T2-flair sequence of magnetic resonance imaging (MRI) in hippocampal sclerosis. MethodsThe clinical data of 135 patients with epilepsy caused by hippocampal sclerosis in the Epilepsy Center of Tianshui Third People's Hospital from March 2019 to December 2020 were analyzed retrospectively, studying the correlation between the changes of hippocampal sclerosis signal and the frequency of epileptic seizures in MRI T2-flair sequence multi axial scanning. ResultsThere were 109 cases of simple hippocampal sclerosis and 26 cases of hippocampal sclerosis with other lesions, including 8 cases of cavernous hemangioma, 9 cases of traumatic or infectious malacia, 2 cases of focal cortical dysplasia, 1 case of cerebral fissure malformation, 1 case of giant gyrus and 5 cases of perinatal brain injury. MRI features of hippocampal sclerosis were as follows: ① hippocampal volume increased slightly, structure blurred, and T2-flair showed slightly increased hippocampal signal in 15 cases, accounting for 11.11%; ② The hippocampal formation was fuzzy, T2-flair was punctate hyperintense, and the volume did not change in 17 cases (12.59%); ③ Hippocampal pyknosis into small lumps, T2-flair sequence showed high signal in 103 cases, accounting for 76.30%. Statistics showed that there was a correlation between hippocampal sclerosis signal and seizure frequency (χ2=94.94, P<0.05). The higher the hippocampal sclerosis signal, the more the seizure frequency. ConclusionMRI T2-flair sequence multi axial scanning can improve the diagnostic accuracy of hippocampal sclerosis. As the change of hippocampal sclerosis signal becomes more obvious, the trend of seizure frequency increases.
This study aims to explore the potential of polyaspartic acid grafted dopamine copolymer (PAsp-g-DA) chelated Fe3+ for magnetic resonance imaging (MRI) visual photothermal therapy. Polyaspartic acid grafted copolymer of covalently grafted dopamine and polyethylene glycol (PAsp-g-DA/PEG) was obtained by the ammonolysis reaction of poly succinimide (PSI), and then chelated with Fe3+ in aqueous solution. The relaxivity in vitro, magnetic resonance imaging enhancement in vivo and photothermal conversion effect at 808 nm were investigated. The results showed that polymeric iron coordination had good near-infrared absorption and photothermal conversion properties, good magnetic resonance enhancement effect, and good longitudinal relaxation efficiency under different magnetic field intensities. In summary, this study provides a new magnetic resonance visual photothermal therapeutic agent and a new research idea for the research in related fields.