Amblyopia is a visual development deficit caused by abnormal visual experience in early life, mainly manifesting as defected visual acuity and binocular visual impairment, which is considered to reflect abnormal development of the brain rather than organic lesions of the eye. Previous studies have reported abnormal spontaneous brain activity in patients with amblyopia. However, the location of abnormal spontaneous activity in patients with amblyopia and the association between abnormal brain function activity and clinical deficits remain unclear. The purpose of this study is to analyze spontaneous brain functional activity abnormalities in patients with amblyopia and their associations with clinical defects using resting-state functional magnetic resonance imaging (fMRI) data. In this study, 31 patients with amblyopia and 31 healthy controls were enrolled for resting-state fMRI scanning. The results showed that spontaneous activity in the right angular gyrus, left posterior cerebellum, and left cingulate gyrus were significantly lower in patients with amblyopia than in controls, and spontaneous activity in the right middle temporal gyrus was significantly higher in patients with amblyopia. In addition, the spontaneous activity of the left cerebellum in patients with amblyopia was negatively associated with the best-corrected visual acuity of the amblyopic eye, and the spontaneous activity of the right middle temporal gyrus was positively associated with the stereoacuity. This study found that adult patients with amblyopia showed abnormal spontaneous activity in the angular gyrus, cerebellum, middle temporal gyrus, and cingulate gyrus. Furthermore, the functional abnormalities in the cerebellum and middle temporal gyrus may be associated with visual acuity defects and stereopsis deficiency in patients with amblyopia. These findings help explain the neural mechanism of amblyopia, thus promoting the improvement of the treatment strategy for amblyopia.
Objective To investigate the effects on myocardial perfusion of simultaneous antegrade/retrograde cardiopiegia （SARC） through a single coronary artery and coronary sinus （CS）. Methods SARC was conducted in isolated pig hearts through CS in conjunction with the left anterior descending （LAD）, the left circumflex （LCX）, or the right coronary artery （RCA） respectively. After injecting magnetic resonance （MR） contrast agent （gadolinium diethyienetriamine pentaacetic acid, Gd-DTPA） into arterial or venous route, the distribution of Gd-DTPA with magnetic resonance imaging（MRI） was monitored and the effluent from the venting coronary arteries to assess the efficacy of SARC for myocardial perfusion was measured. Results Injection of Gd-DTPA into a perfusing artery during SARC resulted in increased signal intensity not only in the territory of the perfusing artery but also in the areas normally served by the other two venting coronary arteries （including the right ventrieuiar free wall）. With Gd DTPA given into the CS during SARC, the myocardium in the territories of the two venting coronary arteries was lightened. Signal intensity of the myocardium in the perfusing artery territory and right ventricuiar free wall remained unchanged. Moreover, a significant amount of effluent was collected from the venting coronary arteries during SARC： the LAD 10.5-17.7 ml/min; LCX 9.7-15.2 ml/min, and RCA 4.7-7.8 ml/min. Conclusion SARC through a single coronary artery and CS can provide homogeneous perfusion to the entire heart and is sufficient to prevent ischemic injury in the myocardium normally supported by the venting coronary arteries.
目的 观察蜂蜇伤致横纹肌溶解的MRI表现，探讨MRI对蜂蜇伤致横纹肌溶解症的诊断价值。 方法 收集2008年9月-2009年12月急诊科及肾内科蜂蜇伤患者4例。对其行蜇伤部位MR增强扫描，对其中1例患者行远离部位肢体扫描。总结MRI征象，评价MRI在蜂蜇伤所致横纹肌溶解临床诊治中的作用。 结果 蜇伤部位显示T1WI稍低，T2WI高信号影像，在T2WI加压脂影像中显示最为清晰，横纹肌损伤有局部随肌间隙扩散趋势，但远端无蜇伤肌肉受累。 结论 蜂蜇伤导致的横纹肌溶解可在MRI影像上得到直观反映。MRI具有良好的软组织对比度，能及时反映横纹肌受累范围及程度、治疗后恢复情况等，可为其临床诊治评估提供有利信息。
Conventional magnetic resonance (MR) pulse sequences typically have an echo time (TE) of 1 ms or longer, providing an excellent contrast between different soft tissues. However, some short T2 tissues appear dark in conventional MR images because the signal from these tissues has decayed to nearly zero before the center of k-space is acquired. Because of the ability of directly imaging short T2 tissues, ultrashort echo time technique has been widely studied in recent years. An overwhelming majority of the studies were carried out at high fields, while many low-field scanner systems are still used in developing countries. To investigate the effects of the delay between analog-to-digital converter sampling and the readout gradient, the TE of the second echo used to calculate the R2* map, and the undersampling ratio on the results of three-dimensional (3D) ultrashort echo time imaging at a low field, we implemented a 3D ultrashort echo time sequence on a 0.35T scanner. Different parameters were used and the reconstructed images and R2* maps were compared. Images reconstructed with slightly varying delays appeared quite different. Different contrast between short and long T2 tissues were found in R2* maps calculated with different echoes. The result of undersampling study indicated that excessive undersampling could cause unwanted blurring, making it difficult to better visualize the short T2 tissues in the R2* map. The results suggested that cautions should be taken in the choice of these parameters in 3D ultrashort echo time imaging. Short T2 tissues can be visualized with appropriate imaging parameters at this low field.
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.
【Abstract】Objective To investigate the MR imaging （MRI） appearances of postoperative residual liver after hepatic resection for hepatocellular carcinoma (HCC) and the MRI features of tumor recurrences.Methods Twenty patients with previous surgical resection of HCC underwent MR examination of upper abdomen for routine follow-up study or due to clinical suspicion of tumor recurrence. MRI protocol included T1W axial unenhanced images and Gadoliniumenhanced sequences, Gadolinium-enhanced VIBE sequence, unenhanced T2W axial images and coronal TrueFisp sequence.Results Thirteen patients showed normal edge of surgical resection, while 6 patients demonstrated MR signs of incision edge recurrence of HCC and 1 patient was suspicious of tumor recurrence at the incision edge. Among the 20 patients, 12 had MRI features of tumor recurrence of the residual liver, including invasion of left, right and common hepatic ducts 3 cases. Three patients had metastatic lymphadenopathy in portal hepatis, portacaval space and retroperitoneal space. Two patients showed extensive tumor implantation of peritoneum and mesentery. Conclusion MRI is effective in differentiating normal surgical incision edge of residual liver from tumor recurrence. It is also very useful for the early detection of intrahepatic and extrahepatic tumor lesions.
Objective To investigate multi-slice spiral CT (MSCT) and MRI features of stasis cirrhosis and the diagnostic value of MSCT and MRI. Methods MSCT and MRI findings of 35 patients with stasis cirrhosis were studied. The size of liver and spleen, the diameter of hepatic vein (HV), enhancement pattern of liver parenchyma, contrast medium reflux in inferior vena cava (IVC) and (or) HV, ascites, number of varices and correlated abnormalities were reviewed. Results The volume index of liver and spleen of 35 patients was 4434.95 cm3 and 621.92 cm3 respectively. The mean diameter of HV of 27 patients (77.1%) was 3.61 cm and HV of other 8 patients (22.9%) were too small to show. Number of patients showed waves of borderline, inhomogeneous pattern of parenchymal contrast enhancement, contrast medium reflux in IVC and (or) HV, varices and ascites was 5 (14.3%), 29 (82.9%), 20 (57.1%), 16 (45.7%), and 6 (17.1%), respectively. Correlated abnormalities included cardiac enlargement 〔4 cases (11.4%)〕, pericardium thickening 〔11 cases (31.4%)〕, and pericardial effusion 〔2 cases (5.7%)〕. Conclusions Stasis cirrhosis mainly demonstrate liver enlargement, inhomogeneous pattern of parenchymal contrast enhancement, contrast medium reflux in IVC and (or) HV, and slight portal hypertension. MSCT and MRI play invaluable roles in diagnosis, differential diagnosis and etiological diagnosis of stasis cirrhosis.
ObjectiveTo explore the value of 3.0 T MRI functional imaging in differential diagnosis of radiation brain injury and recurrence of glioblastoma multiforme.MethodsFrom March 2017 to January 2018, 31 patients diagnosed with brain glioblastoma multiforme in Peking University International Hospital were collected continuously, including 14 cases of tumor recurrence and 17 cases of radiation-induced brain injury. All the patients routinely underwent conventional MRI head scan, three-dimension arterial spin labeling (3D-ASL), dynamic susceptibility contrastperfusion weighted imaging (DSC-PWI), and enhanced MRI scan sequence; related parameters were recorded and compared.ResultsCerebral blood flow (CBF) value of abnormal enhanced area in the recurrence group was significantly higher than that in the brain injury group with 3D-ASL scan (t=3.016, P=0.005), and no difference was found in edema area between the two groups (P>0.05). In the recurrence group, CBF value of abnormal enhanced area was significantly higher than that of the normal area (t=2.628, P=0.014); however, there was no significant difference in the CBF value between the abnormal enhancement foci and the normal areas in the radiation brain injury group (P>0.05). Relative cerebral blood volume (rCBV) ratio (t=2.894, P=0.007) and relative cerebral blood volume (rCBF) ratio (t=2.694, P=0.012) of abnormal enhanced area, as well as rCBV ratio (t=2.622, P=0.013) and rCBF ratio (t=2.775, P=0.010) of edema area in the recurrence group were significantly higher than those in the brain injury group with DSC-PWI scan. No differences were found in relative mean transit time (rMTT) ratio and relative time to peak (rTTP) ratio between the two groups (P>0.05). In the brain injury groupr, CBV ratio (t=2.921, P=0.008) and rCBF ratio (t=3.100, P=0.004) of abnormal enhanced area were significantly higher than those of the edema area, and no difference was found in rMTT ratio or rTTP ratio (P>0.05). In the recurrence group, no difference was found in all focal parameters between abnormal enhanced area and edema area (P>0.05). In diagnosis value analysis, the areas under the curve of CBF in 3D-ASL scan, and rCBF ratio, rCBV ratio in DSC-PWI scan were 0.752, 0.675, and 0.645, respectively; the cut-off values were 34.59, 1.48, and 1.67, respectively; the sensitivities were 79.2%, 61.5%, and 58.3%, respectively; and the specificities were 44.4%, 32.8%, and 22.4%, respectively.ConculsionThe diagnostic value of functional MRI imaging in distinguishing glioblastoma multiforme recurrence and radiation-induced brain injury is high recommendated; further research and clinical application should be needed.