摘要:目的: 探討臂叢神經磁共振成像的技術方法及其可行性。 方法 :對15例正常志愿者行雙側臂叢神經成像:包括常規快速自旋回波序列T1加權(T1W/TSE)、快速自旋回波序列T2加權(T2W/TSE)、快速自旋回波序列T2加權加SPIR脂肪抑制(T2W/SPIR)冠狀位掃描以及彌散加權背景抑制成像序列(DWIBS)軸位掃描。 結果 :T1W/TSE、T2W/TSE、及T2W/SPIR對臂叢節后神經同層顯示率分別為533%、567%和833%;DWIBS MIP重建圖像對臂叢神經的全貌顯示較為完整、清晰、直觀;T1W/TSE、T2W/TSE、T2W/SPIR及DWIBS MIP重建圖像的對比噪聲比分別為109±09、107±13、185±68和299±133,T2W/SPIR序列和DWIBS MIP重建圖像的對比噪聲比明顯高于T1W/TSE和T2W/TSE序列。 結論 :T2W/SPIR序列對臂叢神經的同層顯示率及圖像的對比噪聲比明顯高于常規T1W/TSE、T2W/TSE序列, DWIBS MIP重建圖像能夠顯示臂叢神經的全貌,兩者為臂叢神經成像較為有效的技術方法,對于臂叢神經病變的診斷即具有十分重要的意義。Abstract: Objective: To determine the optimal sequences of brachial plexus with MRI. Methods : Fifteen volunteers were underwent MRI on 15T scanner, the Sequences of T1W/TSE/COR, T2W/TSE/COR, T2W/SPIR/COR and Diffusionweighted imaging with background body signal suppression were performed. Results : The display rates of brachial plexus postganglionic segment nerve showing at the same slice were 533%, 567% and 833% on T1W/TSE/COR, T2W/TSE/COR, T2W/SPIR/COR. Brachial plexus on DWIBS MIP were clear and complete. Contrastnoise ratio of four sequences was 109±09, 107±13, 185±68 and 299±133,respectively. Contrastnoise ratio of T2W/SPIR/COR and DWIBS MIP was significantly higher than that of the other two sequences. Conclusion : Display rate of brachial plexus and contrastnoise ratio of images on T2W/SPIR/COR were higher than those of routine sequences. Image of DWIBS MIP can show the outline of brachial plexus clearly. The two sequences were reliable and effetive techoniquic in diagnosis of brachial plexus lesion.
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.
Focus on the inconsistency of the shape, location and size of brain glioma, a dual-channel 3-dimensional (3D) densely connected network is proposed to automatically segment brain glioma tumor on magnetic resonance images. Our method is based on a 3D convolutional neural network frame, and two convolution kernel sizes are adopted in each channel to extract multi-scale features in different scales of receptive fields. Then we construct two densely connected blocks in each pathway for feature learning and transmission. Finally, the concatenation of two pathway features was sent to classification layer to classify central region voxels to segment brain tumor automatically. We train and test our model on open brain tumor segmentation challenge dataset, and we also compared our results with other models. Experimental results show that our algorithm can segment different tumor lesions more accurately. It has important application value in the clinical diagnosis and treatment of brain tumor diseases.
Taking advantages of the sparsity or compressibility inherent in real world signals, compressed sensing (CS) can collect compressed data at the sampling rate much lower than that needed in Shannon’s theorem. The combination of CS and low rank modeling is used to medical imaging techniques to increase the scanning speed of cardiac magnetic resonance (CMR), alleviate the patients’ suffering and improve the images quality. The alternating direction method of multipliers (ADMM) algorithm is proposed for multiscale low rank matrix decomposition of CMR images. The algorithm performance is evaluated quantitatively by the peak signal to noise ratio (PSNR) and relative l2 norm error (RLNE), with the human visual system and the local region magnification as the qualitative comparison. Compared to L + S, kt FOCUSS, k-t SPARSE SENSE algorithms, experimental results demonstrate that the proposed algorithm can achieve the best performance indices, and maintain the most detail features and edge contours. The proposed algorithm can encourage the development of fast imaging techniques, and improve the diagnoses values of CMR in clinical applications.
There are various examination methods for cardiovascular diseases. Non-invasive diagnosis and prognostic information acquisition are the current research hotspots of related imaging examinations. Positron emission tomography (PET)/magnetic resonance imaging (MRI) is a new advanced fusion imaging technology that combines the molecular imaging of PET with the soft tissue contrast function of MRI to achieve their complementary advantages. This article briefly introduces several major aspects of cardiac PET/MRI in the diagnosis of cardiovascular disease, including atherosclerosis, ischemic cardiomyopathy, nodular heart disease, and myocardial amyloidosis, in order to promote cardiac PET/MRI to be more widely used in precision medicine in this field.
ObjectivesTo assess the accuracy of different types and magnetic field intensity of cardiac magnetic resonance for coronary artery disease.MethodsPubMed, The Cochrane Library, EMbase, WanFang Data, CNKI and CBM databases were searched to collect the studies on different types and magnetic field intensity of cardiac magnetic resonance for coronary artery disease from inception to May 15th, 2017. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Then, data were synthesized by using MetaDisc 1.4, RevMan 5.3 and Stata 12.0 softwares. The pooled sensitivity (Sen), pooled specificity (Spe), pooled positive likelihood ratio (+LR), pooled negative likelihood ratio (–LR), pooled diagnostic odds ratio (DOR) and the area under curve (AUC) of the summary receiver-operating characteristic curve (SROC) were used to assess the diagnostic value of different types and magnetic field intensity of cardiac magnetic resonance.ResultsTwenty diagnostic studies were included, which involved 1 357 patients. The results of meta-analysis showed that (1) based on patient: compared with the gold standard, the pooled Sen, Spe, +LR, –LR, DOR and the AUC of SROC, pre-test probability, post-test probability were (0.87, 95%CI 0.82 to 0.90), (0.88, 95%CI 0.82 to 0.92), (7.33, 95%CI 4.74 to 11.32), (0.15, 95%CI 0.11 to 0.20), (49.53, 95%CI 27.46 to 89.36), (0.93, 95%CI 0.91 to 0.95), 20.00% and 65.00%, respectively. (2) Based on blood vessels: the pooled Sen, Spe, +LR, –LR, DOR and the AUC of SROC, pre-test probability, post-test probability were (0.81, 95%CI 0.76 to 0.85), (0.87, 95%CI 0.81 to 0.91), (6.37, 95%CI 4.37 to 9.30), (0.22, 95%CI 0.17 to 0.27), (29.58, 95%CI 18.53 to 47.22), (0.89, 95%CI 0.86 to 0.92), 20.00% and 61.00%, respectively. (3) Subgroup analysis showed that there was no difference in AUROC of different types of cardiac magnetic resonance, but significant difference was found in AUROC of 1.5T and 3.0T magnetic field intensity.ConclusionsCurrent evidence shows that, compared with gold standard, cardiac magnetic resonance can be regarded as an effective and feasible method for preoperative staging of breast cancer.
ObjectiveTo explore performances of functional magnetic resonance imaging (MRI) in evaluation of hepatic warm ischemia-reperfusion injury.MethodThe relative references about the principle of functional MRI and its application in the assessment of hepatic warm ischemia-reperfusion injury were reviewed and summarized.ResultsThe main functional MRI techniques for the assessment of hepatic warm ischemia-reperfusion injury included the diffusion weighted imaging (DWI), intravoxel incoherent motion (IVIM), diffusion tensor imaging (DTI), blood oxygen level dependent (BOLD), dynamic contrast enhancement MRI (DCE-MRI), and T2 mapping, etc.. These techniques mainly used in the animal model with hepatic warm ischemia-reperfusion injury currently.ConclusionsFrom current results of researches of animal models, functional MRI is a non-invasive tool to accurately and quantitatively evaluate microscopic information changes of liver tissue in vivo. It can provide a useful information on further understanding of mechanism and prognosis of hepatic warm ischemia-reperfusion injury. With development of donation after cardiac death, functional MRI will play a more important role in evaluation of hepatic warm ischemia-reperfusion injury.
The incidence of prostate cancer ranks the second in malignant tumors among elderly males. Multi-parametric MRI (Mp-MRI) is an important mean for detection, staging, and grading of prostate cancer. In order to standardize the collection, interpretation, and reporting of prostate MRI data, the European Urogenital Radiology Society launched the Prostate Imaging Reporting and Data System (PI-RADS) in 2012. Due to some limitations in the application process, the Joint Committee of the American Society of Radiology and the European Society of Radiology issued an updated version of PI-PADS V2 in 2014. In recent years, some studies have been carried out on the effectiveness, accuracy, and consistency of the diagnosis of prostate cancer. This article will review the application and research status of PI-RADS V2 system in the diagnosis of Mp-MRI for prostate cancer.
ObjectiveTo investigate the clinical value of magnetic resonance imaging (MRI) combined with ultrasound (US) contrasting with MRI in evaluating the pathological complete response (pCR) of breast cancer after neoadjuvant chemotherapy (NAC).MethodsThe imaging data of patients with primary invasive breast cancer who completed the surgical resection after NAC and met the inclusion criteria in the Breast Disease Diagnosis and Treatment Center of Affiliated Hospital of Qingdao University from December 2016 to December 2019 were collected retrospectively. These patients were evaluated by MRI and MRI combined with US examination respectively. The results of MRI alone and MRI combined with US were designed into imaging of complete remission (rCR) and imaging of non-complete remission (non-rCR). With results of postoperative pathology as the gold standard, the sensitivity, specificity, and positive predictive value (PPV) of MRI alone and MRI combined with US in predicting pCR of patients with rCR or non-rCR were calculated and which were further analyzed in the 4 subtypes of breast cancer (HR+/HER2+, HR+/HER2–, HR–/HER2+, and HR–/HER2– subtype).Results① According to the inclusion and exclusion criteria, a total of 146 patients with primary invasive breast cancer were included, including 34 cases of HR+/HER2+subtype, 63 cases of HR+/HER2– subtype, 23 cases of HR–/HER2+ subtype, and 26 cases of HR–/HER2– subtype. ② After NAC, 36 cases had a pCR, among which 9 cases (26.5%) were in HR+/HER2+ subtype, 10 cases (15.9%) were in HR+/HER2– subtype, 8 cases (34.8%) were in HR–/HER2+ subtype, and 9 cases (34.6%) were in HR–/HER2– subtype. ③ After NAC, 22 (78.6%) of the 28 patients evaluated by MRI alone achieved pCR, 17 (81.0%) of the 21 patients evaluated by MRI combined with US achieved pCR, and the PPV value of pCR evaluated by MRI alone and MRI combined with US was 78.6% and 81.0%, respectively. ④ Both MRI alone and MRI combined with US predicted NAC showed the highest PPV values in patients with HR–/HER2– subtype breast cancer (85.7% and 100%, respectively), and the lowest values in HR+/ HER2– subtype breast cancer (71.4% and 60.0%, respectively).ConclusionFor the overall patients with primary invasive breast cancer, MRI combined with US is superior to MRI alone in the evaluation of efficacy after NAC, and among the patients with different subtypes of breast cancer, except HR+/HER2– subtype, MRI combined with US is still more effective in predicting efficacy after NAC than MRI alone.
Because of the long acquisition time and spin-echo planar imaging sequence, diffusion weight magnetic resonance image (DWI) should be denoised effectively to ensure the follow-up applications. The commonly used denoising methods which induced from gray level image lack the use of the specific information from multiple magnitude directions. This paper, therefore, proposes a modified linear minimum mean square error (LMMSE) denosing method used for DWI. The proposed method uses the local information to estimate the parameter of the Rician noise and modifies the LMMSE using the information of multiple magnitude directions synthetically. The simulation and experiment of the synthetic DWI and real human brain DWI dataset demonstrate that the proposed method can more effectively remove the Rician noise compared to the commonly used denoising method and improve the robustness and validity of the diffusion tensor magnetic resonance image (DTI).
