Diffusion tensor imaging (DTI) is a rapid development technology in recent years of magnetic resonance imaging. The diffusion tensor interpolation is a very important procedure in DTI image processing. The traditional spectral quaternion interpolation method revises the direction of the interpolation tensor and can preserve tensors anisotropy, but the method does not revise the size of tensors. The present study puts forward an improved spectral quaternion interpolation method on the basis of traditional spectral quaternion interpolation. Firstly, we decomposed diffusion tensors with the direction of tensors being represented by quaternion. Then we revised the size and direction of the tensor respectively according to different situations. Finally, we acquired the tensor of interpolation point by calculating the weighted average. We compared the improved method with the spectral quaternion method and the Log-Euclidean method by the simulation data and the real data. The results showed that the improved method could not only keep the monotonicity of the fractional anisotropy (FA) and the determinant of tensors, but also preserve the tensor anisotropy at the same time. In conclusion, the improved method provides a kind of important interpolation method for diffusion tensor image processing.
【Abstract】ObjectiveTo evaluate the value of MR imaging with a contrast-enhanced multi-phasic isotropic volumetric interpolated breath-hold examination (VIBE) in diagnosis of primary liver carcinoma. MethodsThirty-two consecutive patients with surgical-pathologically confirmed 42 foci of primary carcinoma of liver underwent comprehensive MR examination of the upper abdomen, routine two-dimensional (2D) T1WI and T2WI images were acquired before administration of Gd-DTPA for contrast enhancement. Then, contrast-enhanced multi-phasic VIBE was acquired followed by 2D T1WI images. The lesion appearances on hepatic arterial, portal venous and equilibrium phases of VIBE sequence were carefully observed along with delineation of hepatic arterial and portal venous structures. The lesion detection rates and lesion characterization ability were compared among various MR sequences. Results33(78.6%), 30(71.4%), 38(90.5%) and 42(100%) foci were displayed respectively on T2WI, non-enhanced T1WI, enhanced T1WI and enhanced 3D-VIBE images (P＜0.05). The hepatic arterial anatomy of 30 patients （93.8%） and the portal venous structure of 31 patients （96.9%） were clearly depicted on enhanced 3D-VIBE images. Using MIP and MPR reconstruction techniques, the feeding arteries of 14 foci and draining vein of 12 foci were clearly displayed.ConclusionHigh-quality 3D-VIBE images are not only better than 2D images in lesion detection and characterization for primary liver carcinoma, but also able to provide much more information about hepatic vascular anatomy.
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 observe the pathological changes of central retinal artery occlusion (CRAO) by optical coherence tomography (OCT).MethodsFifty-three eyes of 53 patients who were diagnosed as CRAO in our center between January 2001 to January 2004 underwent the examination by OCT. The intervals between the disease onset and OCT examination were less than 2 weeks. The scan modes of OCT were horizontal or vertical line scan. The locations of scanning were macular, posterior pole of retina, optical papilla and the focus of bleeding or exudation.ResultsThe OCT pathological changes of CRAO in vivo includes increase of retinal thickness and reflex of retina, width of dark layer of photoreceptor (edema), edema or cystoid edema of fovea, retinal bleeding, cotton-wool spot and papilla edema. Four patients who had ciliary retinal artery showed normal retinal structure in the supply region of ciliary retinal artery.ConclusionOCT can display the pathological changes of retinal tissues in CRAO in vivo, especially on the old patients or the patients with systemic disease who were contraindicated by FFA. The unique OCT image of pathological changes of CRAO supply the objective signs for the instant clinical diagnosis.(Chin J Ocul Fundus Dis, 2005,21:74-78)
ObjectiveThis review has summarized in detail the advances in computed tomography (CT) and magnetic resonance imaging (MRI) imaging in evaluating the efficacy of targeted therapy for gastrointestinal stromal tumor (GIST).MethodsTo summarize the image-related guidelines, consensus, international conference reports, and relevant knowledge of clinical research on the evaluation of the efficacy of GIST targeted therapy in recent years.ResultsThe CT and MRI manifestation after targeted treatment of GIST was closely related to pathological changes, including necrosis, cystic degeneration, and bleeding. CT was the preferred imaging method. Functional magnetic resonance imaging, such as diffusion weighted imaging (DWI), had made some progress. The main criteria for evaluating the efficacy of GIST targeted therapy were RECIST 1.1 and Choi criteria.ConclusionCT and MRI play an important role in evaluating the efficacy of targeted therapy for GIST.
ObjectivesTo investigate the diagnostic value of different diffusion-weighted MRI (DWI) models between two Gaussian DWI models including mono-exponential and bi-exponential, and the non-Gaussian kurtosis model in poorly differentiated pancreatic ductal adenocarcinoma.MethodsSubjects comprised 52 patients with poorly differentiated pancreatic ductal adenocarcinoma which had been confirmed by surgery. All patients underwent DWI (1.5T, multi-b values: 0, 50, 100, 150, 200, 500, 800, 1000, 1 500, 2 000s/mm2). Mean values of DWI-derived metrics ADCstandard, ADCslow, ADCfast, f, MD, MK and ADCstandard were calculated from regions of interest in all tumours and non-tumorous parenchyma and compared. ANOVA and Mann Whitney U test was used to compare the MRI paremeters. ROC was used to evaluate the diagnostic efficiency.ResultsMean ADCstandard, ADCfast, f and MK values showed significant differences between tumours and non-tumorous parenchyma (P<0.05). AUC for ADCstandard, MD, ADCfast and f were 0.705, 0.665, 0.648, 0.614, respectively. The ROC curve integrated with ADCstandard and MD had better diagnostic efficiency (AUC was about 0.754).ConclusionsADCstandard, ADCfast, f and MK values can differentiate tumours from non-tumorous parenchyma. The combination of Gaussion distribution model and non-Gaussion distribution model has the potential to increase the diagnostic accuracy of DWI in patients with pancreatic ductal adenocarcinoma.
Objective To evaluate the values of magnetic resonance imaging (MRI) in the diagnosis of acetabular labral tears (ALT) by meta-analysis. Methods The studies concerning the diagnosis of ALT tears by using MRI from January 1990 to October 2016 were searched in the databases such as CBM, VIP, WanFang Data, CNKI, PubMed, EMbase, The Cochrane Library and Web of Science. Two reviewers independently screened literature, extracted data, and assessed the risk of bias of included studies by using the QUADAS-2 tool. Then, meta-analysis was performed by using Stata 12.0 software. The pooled sensitivity, specificity, positive likelihood ratio (+LR), negative likelihood ratio (–LR) and the diagnostic odds ratio (DOR) were calculated, and the summary receiver operating characteristic curve (SROC) was drawn and the area under the carve was calculated. Results A total of 25 studies from 21 articles were included, involving 1 123 hips from 1 099 patients. The results of meta-analysis showed that, the pooled Sen, Spe, +LR, –LR, DOR and area under SROC curve of MRI for diagnosing ALT were 0.66 (95% CI 0.38 to 0.86), 0.72 (95% CI 0.47 to 0.89), 2.37 (95% CI 1.18 to 4.67), 0.48 (95% CI 0.25 to 0.92), 4.97 (95% CI 1.60 to 15.47), 0.75 (95% CI 0.71 to 0.79). The pooled Sen, Spe, +LR, –LR, DOR and area under SROC curve of MRA for diagnosing ALT were 0.86 (95% CI 0.80 to 0.90), 0.71 (95% CI 0.55 to 0.83), 2.91 (95% CI 1.77 to 4.80), 0.20 (95% CI 0.13 to 0.32), 14.44 (95% CI 5.80 to 35.95), 0.87 (95% CI 0.84 to 0.90), respectively. Conclusion MRI is efficiency diagnostic method for acetabular labral tears.
ObjectiveTo summarize the status and progress of imaging studies of pancreatic neuroendocrine neoplasms (pNENs).MethodThe relevant literatures published recently at domestic and abroad about the imaging of pNENs were collected and reviewed.ResultsDue to poor visibility of pancreatic body and tail, the application of ultrasound (US) was limited. Compared with US, endoscopic ultrasound (EUS) and contrast-enhanced ultrasound (CEUS) could improve the detection rate of pNENs. The ability of plain CT scans to differentiate pathological grades was still controversial, but the value of enhanced scan was higher. CT texture analysis was feasible in the discrimination of nonhypervascular pNENs and pancreatic ductal adenocarcinoma (PDAC). Teta2 was the parameter with the highest diagnostic performance. The enhanced features of MRI were similar to CT. Combined with the apparent diffusion coefficient (ADC) value, the diagnostic and classification capabilities of MRI were improved, and the sensitivity and specificity of different ADC thresholds were also different. 68Ga-tetraazacyclododecane tetraacetic acid (68Ga-DOTA) peptide PET-CT had good preliminary diagnostic value for well-differentiated pNENs, and 18Fluoro-fluorodeoxyglucose (18F-FDG) PET-CT had limited diagnostic value.ConclusionsSomatostatin receptor imaging is of high diagnostic value and can guide clinical treatment and predict prognosis, but it has not been widely used in China. Conventional morphological images have advantages in the diagnosis and classification of pNENs. Therefore, it is important to choose a proper image inspection method.
ObjectiveTo explore the clinical value of dual-source CT perfusion imaging (CTPI) in the assessment of cerebral hemodynamic changes in patients with internal carotid atherosclerosis. MethodsThirty patients diagnosed to have internal carotid atherosclerosis by CT angiography examination with various degrees of stenosis or occlusion were treated between January 2012 and May 2013. Whole brain perfusion imaging was performed on all the patients. We rebuilt the CTPI figure parameters respectively, including cerebral blood volume (CBV), blood flow (CBF), mean transit time (MTT) and time to peak (TTP) to assess brain tissue perfusion. ResultsIn the 30 patients with internal carotid atherosclerosis, 8 had mild stenosis lumen, 12 moderate stenosis, 7 severe stenosis and 3 had occlusion. In mild stenosis cases, TTP of stenosis-side vessels was higher than those of coutralateral side (P<0.05), and there were no significant differences in other perfusion parameters between bilateral vessels among mild stenosis cases (P>0.05). MTT and TTP of stenosis-side vessels were higher than those of contralateral side in moderate stenosis cases (P<0.05). In severe stenosis or obstruction cases, MTT and TTP of stenosis-side vessels were higher than those of contralateral side, while CBF and CBV of stenosis-side vessels were lower than contralateral side (P<0.05). Twenty-two in the 30 cases had perfusion abnormalities, and there was a significant difference between the stenosis side cerebral perfusion and the healthy side mirror area (P<0.05). ConclusionCTPI can reflect brain tissue perfusion early and comprehensively, and fully reflect internal carotid atherosclerosis caused by severe stenosis or occlusion of cerebral hemodynamic changes, which provides important information for clinical treatment and helps clinicians to formulate individualized treatment plan.