Acute aortic dissection is featured as sudden onset and high mortality. Regardless early optimal surgical intervention and strict medical therapy, incidence of late complications is still high. Thus, specific imaging techniques and precise measurement of biomarkers to predict complications are needed. In the present study, we reviewed related papers to compare traditional imaging techniques (computed tomography, echocardiography) and magnetic resonance imaging (MRI) in the diagnosis of chronic aortic dissection. In addition, we discussed how to further evaluate aortic dissection by MRI.
When applying deep learning algorithms to magnetic resonance (MR) image segmentation, a large number of annotated images are required as data support. However, the specificity of MR images makes it difficult and costly to acquire large amounts of annotated image data. To reduce the dependence of MR image segmentation on a large amount of annotated data, this paper proposes a meta-learning U-shaped network (Meta-UNet) for few-shot MR image segmentation. Meta-UNet can use a small amount of annotated image data to complete the task of MR image segmentation and obtain good segmentation results. Meta-UNet improves U-Net by introducing dilated convolution, which can increase the receptive field of the model to improve the sensitivity to targets of different scales. We introduce the attention mechanism to improve the adaptability of the model to different scales. We introduce the meta-learning mechanism, and employ a composite loss function for well-supervised and effective bootstrapping of model training. We use the proposed Meta-UNet model to train on different segmentation tasks, and then use the trained model to evaluate on a new segmentation task, where the Meta-UNet model achieves high-precision segmentation of target images. Meta-UNet has a certain improvement in mean Dice similarity coefficient (DSC) compared with voxel morph network (VoxelMorph), data augmentation using learned transformations (DataAug) and label transfer network (LT-Net). Experiments show that the proposed method can effectively perform MR image segmentation using a small number of samples. It provides a reliable aid for clinical diagnosis and treatment.
ObjectiveTo investigate clinical value of MRI examination in diagnosis of xanthogranulomatous cholecystitis (XGC), and to analyze pathologic correlation of various imaging findings. MethodsMRI imaging data of 7 patients with XGC proved by surgery and pathology who underwent entire MRI sequences examination in Sichuan Provincial People's Hospital from Jan. 2013 to Dec. 2015, were analyzed retrospectively. The thickness and contrast enhancement of gallbladder wall, gallbladder wall nodules, completeness of gallbladder mucosa lines, gallbladder stones, and the changes around the gallbladder were focused in every patient. ResultsIn 7 patients with XGC: gallbladder wall thickening occurred in all patients, in which 2 patients were local thickening, 5 patients were diffuse thickening; ‘hypodense band sign' was found by enhance scan in 4 patients; the multiple intramural nodules were presented in 5 patients, which were low signal intensity on T1WI image and high signal intensity on T2WI image; the mucosal lines were continuous in 6 patients and discontinuous in 1 patient; 6 patients combined with cholecystolithiasis. The fat layer around the gallbladder was found fuzz in 7 patients, liver and gallbladder boundaries were not clear in 7 patients; temporal enhancement of arterial phase in liver parenchyma was observed in all patients, and 1 patient combined with liver abscess. Hilar bile duct narrowed and intra-hepatic bile duct dilated in 2 patients, intra-hepatic and extra-hepatic bile duct slightly dilated in 2 patients (lower part of the choledochus stone was found in 1 patient), liver cyst was observed in 3 patients, single or double kidney cyst was observed in 4 patients; all patients were not found intraperitoneal or retroperitoneal swelling lymph nodes. ConclusionMRI examination can accurately describe various imaging features of XGC, so MRI has important value in diagnosis of XGC.
OBJECTIVE:To investigate the diagnostic meaning of MRI in intraocular tumors. METHODS:Forty-six cases of confirmed intraocular tumors,including choroidal melanoma(20 cases),retinoblastoma(18 cases),Coats disease(6 cases)and choroidal hemangioma(2 cases),were studied with MRI and compared with ultrasonography and CT. RESULTS:In making discoveries about intraocular tumors,there were no sighificant difference between MRI and B-ultrasonography or CT （P＞0.03，chi;2=1.0716）while there were highly statistic sighificance in dediding characters and position （P＜0.01，deceding character chi;2=29.8314，positionchi;2=13.659）of them. CONCLUSION:Among the examinations to find out about the position,character and secondary pathological insults of in traocular tumors MRI might be more available than CT and ultrasonography. （Chin J Ocul Fundus Dis,1997,13:93-95 ）
The effect of deep brain stimulation (DBS) surgery treatment for Parkinson's disease is determined by the accuracy of the electrodes placement and localization. The subthalamic nuclei (STN) as the implant target is small and has no clear boundary on the images. In addition, the intra-operative magnetic resonance images (MRI) have such a low resolution that the artifacts of the electrodes impact the observation. The three-dimensional (3D) visualization of STN and other nuclei nearby is able to provide the surgeons with direct and accurate localizing information. In this study, pre- and intra-operative MRIs of the Parkinson's disease patients were used to realize the 3D visualization. After making a co-registration between the high-resolution pre-operative MRIs and the low-resolution intra-operative MRIs, we normalized the MRIs into a standard atlas space. We used a special threshold mask to search the lead trajectories in each axial slice. After checking the location of the electrode contacts with the coronal MRIs of the patients, we reconstructed the whole lead trajectories. Then the STN and other nuclei nearby in the standard atlas space were visualized with the grey images of the standard atlas, accomplishing the lead reconstruction and nerve nuclei visualization near STN of all patients. This study provides intuitive and quantitative information to identify the accuracy of the DBS electrode implantation, which could help decide the post-operative programming setting.
ObjectiveAicardi and Goutières syndrome was first reported as a rare hereditary encephalopathy with white matter involvement in 1984. Typical clinical manifestations include severe mental motor development retardation or regression, pyramidal and extrapyramidal symptoms and signs, epilepsy, microcephaly and frostbite.MethodsTo collect a case of patient who presented with convulsions 14 days after birth without obvious inducement. The child was diagnosed as epilepsy in the local hospital and the symptoms improved after treatment with antiepileptic drugs. At 4 months, the child presented nods and clenched fists, and was diagnosed as infantile spasm. After Adrenocorticotrophic hormone and drug treatment, the symptoms gradually improved. Due to upper respiratory track infection, the child was aggravated at the age of 1 year and 2 months, and then diagnosed as Aicardi-Goutières syndrome by video EEG, skull MRI, fundus and gene screening.ResultsSurgery and treatment with antiepileptic drugs significantly improved the symptoms of the child, and the pathological biopsy of the brain tissue supported the previous diagnosis.ConclusionsThe report of this case will help to improve the clinician's diagnosis and treatment of Aicardi-Goutières syndrome.
It is difficult to reflect the properties of samples from the signal directly collected by the low field nuclear magnetic resonance (NMR) analyzer. People must obtain the relationship between the relaxation time and the original signal amplitude of every relaxation component by inversion algorithm. Consequently, the technology of T2 spectrum inversion is crucial to the application of NMR data. This study optimized the regularization factor selection method and presented the regularization algorithm for inversion of low field NMR relaxation distribution, which is based on the regularization theory of ill-posed inverse problem. The results of numerical simulation experiments by Matlab7.0 showed that this method could effectively analyze and process the NMR relaxation data.
Urokinase plasminogen activator receptor (uPAR) is a membrane protein which is attached to the cellular external membrane. The uPAR expression can be observed both in tumor cells and in tumor-associated stromal cells. Thus, in the present study, the human amino-terminal fragment (hATF), as a targeting element to uPAR, is used to conjugate to the surface of superparamagnetic iron nanoparticle (SPIO). Flowcytometry was used to examine the uPAR expression in different tumor cell lines. The specificity of hATF-SPIO was verified by Prussian blue stain and cell phantom test. The imaging properties of hATF-SPIO were confirmed in vivo magnetic resonance imaging (MRI) of uPAR-elevated colon tumor. Finally, the distribution of hATF-SPIO in tumor tissue was confirmed by pathological staining. Results showed that the three cells in which we screened, presented different expression characteristics, i.e., Hela cells strongly expressed uPAR, HT29 cells moderately expressed uPAR, but Lovo cells didn't express uPAR. In vitro, after incubating with Hela cells, hATF-SPIO could specifically combined to and be subsequently internalized by uPAR positive cells, which could be observed via Prussian blue staining. Meanwhile T2WI signal intensity of Hela cells, after incubation with targeted probe, significantly decreased, and otherwise no obvious changes in Lovo cells both by Prussian blue staining and MRI scans. In vivo, hATF-SPIO could be systematically delivered to HT29 xenograft and accumulated in the tumor tissue which was confirmed by Prussian Blue stain compared to Lovo xenografts. Twenty-four hours after injection of targeting probe, the signal intensity of HT29 xenografts was lower than Lovo ones which was statistically significant. This targeting nanoparticles enabled not only in vitro specifically combining to uPAR positive cells but also in vivo imaging of uPAR moderately elevated colon cancer lesions.