超顺磁氧化铁标记神经干细胞移植治疗帕金森病大鼠脑MRI改变的研究

目的研究应用超顺磁氧化铁（SPIO）标记神经干细胞（NSCs）移植治疗帕金森病（PD）大鼠脑部MRI的改变。方法从大鼠胚胎脑中分离培养中脑NSCs,用脂质体转染法将SPIO标记NSCs;同时制作大鼠PD模型,SPIO标记的NSCs移植到PD大鼠右侧纹状体区,分别在移植后1周、2周、4周、6周、8周和10周给大鼠行MRI检查,2周、4周、6周、8周、10周时进行旋转行为评分,并与NSCs组和对照组比较。结果脑内移植SPIO标记NSCs的PD大鼠1周后MRI检查显示在移植区呈低信号改变;移植后10周,在T2和T2梯度回波仍可观察到移植区的低信号,同时移植区有混杂信号。NSCs移植大鼠的旋转行为评分在移植后2-10周明显少于对照组（均P〈0.05）。结论SPIO标记的NSCs可以在MRI上显示其在移植大鼠脑部的分布和存活情况,有利于NSCs移植治疗PD后的疗效观察。     

1.5T超导磁共振制冷系统的工作原理及日常维护

介绍GE 1.5T超导磁共振制冷系统的组成和工作原理,讨论日常维护的要点及其必要性。     

Brainstem compression by basilar artery anomalies as visualized by MRI

Summary The use of MRI in the diagnosis of vascular anomalies of the basilar artery is demonstrated in two cases. The first patient had a partially thrombosed giant aneurysm of the basilar artery; the second had an atypical course of the basilar artery. MRI is indicated whenever other imaging procedures do not provide a definite diagnosis or the use of contrast medium for conventional X-ray examination or computed tomography is contraindicated.     

The effect of mechanical deformation on magnetic properties and MRI artifacts of type 304 and type 316L stainless steel

The purpose of this study was to evaluate the influence of composition and deformation of biomedical stainless steels on mechanical properties, magnetic properties, and MRI artifacts. Type 304 and Type 316L samples were prepared using standard wire-drawing techniques. Mechanical properties were determined using standard test methods. The amount of ferromagnetic phase present was estimated using a Severn Gage and x-ray diffraction. Magnetic field attraction and artifacts were determined using previously described techniques. The strength of both steels increased significantly with increasing deformation. None of the type 316L wires transformed to the magnetic phase. The amount of magnetic phase in the type 304 wires increased with increasing deformation. There was no magnetic field attraction, and artifacts were minimal for all of type 316L wires and the undeformed type 304 wire. Deflection and artifacts were significant for the deformed type 304 stainless steel. These results provide guidance regarding the use of type 304 and type 316L stainless steels for bioimplants. In this regard, type 316L stainless steel seems to be a more acceptable material with respect to MR compatibility.     

Dynamic MRI of the gallbladder lesions: Differentiation of benign from malignant

Forty-nine pathologically proven gallbladder lesions were evaluated in 45 patients using dynamic MRI with a spoiled gradient pulse sequence (SPGR), to access the ability of this technique to differentiate benign from malignant gallbladder lesions. The studies were reviewed retrospectively. Signal intensity of the lesions were measured. Twenty-one malignant and 28 benign lesions were classified into three categories: polypoid, diffuse wall thickening, and exophytic. Early and delayed enhancement patterns were evaluated. For the polypoid masses, malignant lesions (n = 9) demonstrated early and prolonged enhancements, whereas benign lesions (n = 14) had early enhancement with subsequent washout (P < .05). For diffuse gallbladder wall thickening, malignant lesions (n = 6) demonstrated early and prolonged enhancement and benign lesions (n = 14) showed relatively slow, prolonged enhancement (P < .05). The exophytic masses (n = 6) all were malignant and demonstrated early and prolonged enhancement. Dynamic MRI can help differentiate benign from malignant gallbladder lesions.     

MRI in subacute combined degeneration

We describe a patient with clear lesions in the spinal cord on MRI due to subacute combined degeneration. T2-weighted images clearly showed abnormal high signals in the posterior columns, which disappeared on recovery from the disease.     

Gadolinium ring enhancement and mass effect in acute disseminated encephalomyelitis

A 9-year-old boy presented with a subacute history of optic neuritis followed by brainstem involvement, with fever and a lymphocytic pleocytosis in the cerebrospinal fluid. Gadolinium-enhancing ring lesions were demonstrate in the white matter of the cerebrum, brainstem and cerebellum on day 17 of the illness, all appearing simultaneously as part of a monophasic illness. A parietal lesion exerted mass effect. Needling and biopsy yielded no evidence of a pyogenic lesion, tumour or tuberculosis and showed vasculitis. There was insufficient material for myelin staining. Dexamethasone therapy lead to rapid improvement of the radiological lesions: MRI and CT on day 34 of the illness showed complete clearing of the lesions except for residual abnormality at the biopsy site.     

MR appearance of parasymphyseal insufficiency fractures of the os pubis

 Objective. To clarify the MRI features of parasymphyseal insufficiency fractures of the os pubis. Design and patients. MRI was performed in four postmenopausal women with parasymphyseal insufficiency fractures. The diagnosis was confirmed with plain films in every patient. T1-weighted and T2-weighted images were obtained in four patients using a 1.5-T unit. Postcontrast T1-weighted imaging was also done in three patients. Results and conclusions. MRI of pubic parasymphyseal insufficiency fracture characteristically demonstrates a hyperintense mass lesion with a hypointense rim on T2-weighted imaging, showing peripheral and septal enhancement after contrast administration. It is important to have this entity in mind in patients with osteoporosis, especially in patients with a history of pelvic irradiation for malignant disease, so as not to misinterpret it as a chondroid tumor or bone metastasis.     

Diffuse liver disease: MRI with Gd-DTPA versus CT and ultrasound

Twenty-nine patients with diffuse liver disease were examined by ultrasound, CT and MRI. MRI was performed using T1- and T2-weighted spin-echo sequences as well as fast gradient-echo-sequences. The paramagnetic contrast agent Gd-DTPA was applied intravenously (0.1 mmol/kg). in patients with hepatitis, MRI could be used in guiding liver biopsies as inflammatory changes were clearly delineated. CT and ultrasound were superior to MRI in the detection of focal or diffuse fatty degeneration. On the other hand MRI was more helpful in differentiating fatty changes and neoplasm. In liver cirrhosis, fibrotic changes were most clearly demonstrated by MRI. In patients suffering from hemochromatosis MRI offers advantages over CT and ultrasound in the diagnosis and follow up due to the paramagnetic properties of iron, resulting in a reduction in signal intensity. In patients with Wilson's disease a characteristic pattern of parenchymal changes was seen. Administration of Gd- DTPA contributes additional information about perfusion conditions in the liver parenchyma, however this information was not of diagnostic relevance in the cases we studied. Correspondence to: T.J. Vogl     

脊髓萎缩（附2例报告）

本文报告了两例脊髓萎缩，并结合文献复习讨论了该病的好发部位、病因、临床表现、诊断和治疗。脊髓萎缩的病因多为继发性，也可为特发性。根据临床表现结合脊髓ＣＴ造影及ＭＲＩ检查，可以明确诊断。