Objective To determine the safety of the fetal olfactory ensheathing cell(OEC) transplantation in patients with chronic spinal cord injury (SCI) by examination of the magnetic resonance imaging (MRI). Methods A prospective clinical study involving 16 patients with chronic SCI was designed to investigate the feasibility and biological safety of the fetal OEC transplantation in treatment of SCI. The olfactory bulbs from the 3-4-month-old aborted human fetuses following the strict ethical guidelines were harvested and trypsinized down to single fetal OEC. These cells were then cultured for 12-17 days and were prepared for a clinical use. From November 2001 to December 2002, 16 patients with chronic SCI were randomly enrolled. The patients suffered from SCI for1.5-8 years (average 4-3 years) after the injury. The suspension (50 μl) containing about 1×106 fetal OECs was transplanted by an injection into the patients’ spinal cords above and below the injury site. All the patients were assessed before thetransplantation and were followed up with MRI for 29-42 months (average 38 mon)after the transplantation. Results No cell-related adverse effects were observed in any patient during the followup period. The follow-up with MRI did not reveal any development of optic glial tumor, tumor-like mass, new hemorrhage,edema, expanding cyst, new cyst formation, infection or disruption of the neuralstructure in the transplant site of all the patients. Conclusion This is the first clinical study demonstrating the long-term safety of theOEC therapy for SCI. The results indicate that our protocol is feasible and safe in treatment of patients with chronic SCI within 38 months after the injury. Although the size of the samples for our study was not big enough, the positive results of the study have encouraged us to make a further research in this field.
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.
【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.
Objective To observe the changes of visual pathway of central nervous system in patients with glaucoma.Methods Thirty-five subjects were enrolled in this prospective study. There were seven patients of chronic primary angle closure glaucoma with bilateral visual field defects, 12 patients of primary open angle glaucoma with bilateral visual field defects, and 16 normal subjects. GE Signa HD 1.5 T magnetic resonance scanners and head eight phased array were used. The mean fractional anisotropy (FA) and the mean average diffusion coefficient (DCavg) of white matter tracts in visual pathway of bilateral optic nerve, optic chiasma, bilateral optic tract，bilateral optic radiation were measured by diffusion tensor imaging, meanwhile the white matter tracts were reconstructed by fiber tracking system. The volumes of lateral geniculate body were measured by coronal proton density weighted magnetic resonance imaging.Results The differences of FA among bilateral optic nerve, optic chiasma, bilateral optic tract，bilateral optic radiation were statistically significant (F=25.985，20.626，12.262，22.399，21.708，24.994，22.774；P＜0.05). There was no difference of DCavg among bilateral optic nerve, optic chiasma, bilateral optic tract，bilateral optic radiation（F=2.097，2.178，0.530，0.983，0.608, 0.866, 1.504；P＞0.05）. The differences of volume of lateral geniculate body among three groups were statistically significant （F=18.631，17.274；P＜0.05）. Conclusion There is degeneration in visual pathway of central nervous system in patients with glaucoma.
Objective To analyze the correlation and difference of axial length (AL) measurements by comparing magnetic resonance imaging (MRI) of different pulse sequence with IOL Master of normal eyes. Methods The 67 emmetropic volunteers were selected by the slit lamp microscope, direct ophthalmoscope and refractive examination in this study. The patients included 30 males and 37 females. The patientsprime; ages ranged from eight to 21 years, with a mean age of 14.9 years. Fast spin echo (FSE) T1WI, FSE T2WI, fluid attenuated inversion recovery (FLAIR) T2WI, FSPGR T1WI were performed. The axial (AX) and oblique sagittal (OS) sections were taken and the AL from MRI section with different sequences were measured. The AL taken by IOL-Master was used as standard. The difference and correlation between measurements of two methods were analyzed. Results The AL of AX FSE T1WI, AX FSE T2WI, AX FLAIR T2WI, AX FSPGR T1WI, OS FSE T1WI, OS FSE T2WI, OS FLAIRT2WI and OS FSPGR T1WI were (24.14plusmn;0.81), (24.26plusmn;0.81), (23.87plusmn;0.79), (24.11plusmn;0.82), (24.08plusmn;0.86), (24.22plusmn;0.81), (23.84plusmn;0.79) and (24.03plusmn;0.81) mm, respectively. The AL of IOLMaster was (23.91plusmn;0.80) mm. The differences of AL between IOL-Master and various MRI sequences were statistically significant (t=－13.54,－23.20, 4.08, －15.55, －8.00, －23.22, 5.25, －10.62;P＜0.01). There were excellent correlations between IOL-Master and various MRI sequences (r=0.97, 0.96, 0.98, 0.97, 0.96, 0.80, 0.98, 0.97;P＜0.01). Conclusion There are differences and significant correlations between MRI sequences and IOL-Master.
ObjectiveTo introduce the new nomenclature scheme of the International Working Group (1995) on hepatic nodules, and summarize the imaging features of various hepatic nodules in light of their pathological characteristics, and evaluate the diagnostic values of various imaging facilities.MethodsUltrasound, computed tomography(CT), magnetic resonance imaging(MRI), and angiographic CT were reviewed and introduced.ResultsMany of these types of hepatic nodules play a role in the de novo and stepwise carcinogenesis of hepatocellular carcinoma(HCC) in the following steps: regenerative nodule, lowgrade dysplastic nodule, highgrade dysplastic nodule, small HCC, and large HCC. Accompanying such transformations, there are significant alterations in the blood supply and perfusion of these hepatic nodules.ConclusionModern stateoftheart medical imaging facilities can not only delineate and depict these hepatic nodules, but also provide important clues for the characterization of focal hepatic lesions in most cases, thus facilitating the early detection, diagnosis and management of HCC in its early stage.
Magneticaly labeled stem cells and magnetic resonance imaging(MRI) technology is an effective tracking method in vivo study, which has high spatial-temporal resolution. Gadolinium, which shows positive T1 signals and iron oxide showing negative T2 signals are the two often used contrast agents. The latter also include superparamagnetic iron oxide particle and ultrasmall superparamagnetic iron oxide particle. Transfection agents, e.g. poly-L-lysine and protamine sulfate，can enhance magnetical nanoparticles labeling stem cells. The biological characteristics of labeled stem cells did not seem to be altered. MRI can detect the labeled stem cells’ signals and also can track changes of signal in intensity and size with time past. In conclusion, MRI tracking magneticaly labeled stem cells represents a method for noninvasivly monitoring the existence and migration of engrafts.
Objective To investigate the magnetic resonance imaging （MRI） assessment and functional evaluation of chronic pancreatitis （CP）. Methods Literatures about MRI assessment of CP （especially the evaluation of pancreatic exocrine function with MRI） were reviewed. Results Some early parenchymal changes （pancreatic size，signal intensity of pancreas， and enhancement pattern） in the CP could be visualized by MRI；ductal changes could be visualized by MR cholangiopancreatography （MRCP）；and secretin-stimulated MRCP （combination of both morphologic and functional evaluation） not only improved the visualization of pancreatic duct and side branches，but also allowed evaluation of the pancreatic exocrine function noninvasively. Secretin-stimulated diffusion weighted imaging also could be used as a noninvasive method to assess pancreatic exocrine function. Conclusions Conventional MRI and （or） secretin-stimulated MRI can become valuable means in CP （especially early-stage CP）， with furnishing morphologic and functional information simultaneously. However，further research is needed to verify the diagnostic accuracy of these modalities.
Objective To investigate the feasibility of magnetic resonance diffusion tensor imaging (MRDTI) technique in displaying myocardial fiber architecture. Methods In five ex vivo swine heart, diffusion tensor imaging (DTI) was acquired in 25 directions within 2 hours after excision. The myocardial fiber was reconstructed by using brain white matter tractography algorithm to display its course, distribution and arrangement. Results In the swine heart 1 hour after excision, MRDTI revealed that the arrangement of the myocardial fiber had certain continuity. It spiraled and twisted to form the left and right ventricle. The divection of general myocardial fiber in the left ventricle was vertical below endocardium, horizontal below epicardium and oblique in stratum medium, which is consistent with the theory of ventricular myocardial band. Conclusion MRDTI can reveal the myocardial fiber architecture, showing its integrity and arrangement, and at some level confirming the theory of ventricular myocardial band.
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.