Infantile fibrosarcoma: radiological and clinical features

Two cases of infantile fibrosarcoma are described. This rare childhood malignancy of mesodermal origin usually affects the lower limbs, as it did in both of our cases. Previously, the only treatment option available involved some form of radical and often mutilating surgery. More recently, combination chemotherapy has given good results, with the effect that various imaging modalities have become important in assessing both the initial extent of disease and the response to treatment. Computed tomography has the advantage of demonstrating the amount of osseous involvement, but at the expense of a considerable dose of ionizing radiation. On the other hand, magnetic resonance imaging, with its multiplanar capacity, gives superior demonstration of breaching of tissue planes, which has important implications for planning of surgery. However, as in other soft tissue tumours, changes in signal characteristics with treatment have proved less specific than was originally anticipated.     

MRI顺磁性造影剂增强及护理

目的 :进一步探讨 MRI增强前后的准备与护理方法。材料与方法 :共增强 833例 ,男 5 85例 ,女 2 4 8例。使用顺磁性造影剂 Gd- DTPA,按 0 .2 m L/kg体重给药。其中双倍量增强 110例 ,增强前认真履行告知义务和签署同意书。发生造影剂外漏者给予鲜马铃薯片外敷。结果 :增强效果达良好以上共 82 5例 ,占 99% ,未发生严重负反应。 3例造影剂外漏 ,鲜马铃薯片外敷后 3h痊愈。结论 :增强前充分细致的准备是保证增强效果的重要因素。认真履行告知义务和签置同意书 ,不仅尊重了病人的权利 ,也是依法行医 ,保证医疗安全的需要     

Fluid-fluid levels in cavernous hemangioma of soft tissue

Five cases of cavernous hemangioma with fluid-fluid levels on magnetic resonance imaging and/or computed tomography are reported. The signal characteristics were those of blood and histological analysis of the fluid-fluid levels showed that they were blood-filled cavities in the tumor. Although this finding itself is not specific, it may help in confirming the diagnosis of cavernous hemangioma.     

Artifacts due to stimulus correlated motion in functional imaging of the brain

To assess the effect of stimulus correlated motion on the appearance of functional magnetic resonance images, conventional visual and motor protocols were each performed by four normal volunteers and an image co-registration technique was used to retrospectively monitor subject motion. In three studies synthetic data sets were constructed from single baseline images using the positional information obtained from the co-registration procedure. Cumulative difference images were then created from both the synthetic and functional image sets. Stimulus correlated motion was detected in all eight studies and the synthetic cumulative difference images showed striking similarities to the equivalent functional images in each case.     

MRI诊断儿童脑白质病变的初步探讨

目的 :初步探讨 MRI诊断儿童脑白质病变的作用和特异征象。方法 :对 MRI诊断为脑白质病变的病例 4 8例进行观察 ,分析病灶的 MRI征象 ,包括病灶出现的部位、形态、范围及其他合并表现。结果 :1病灶发生的部位 ,多位于双侧侧脑室三角部周围的白质内 ,依次为侧脑室前角周围、半卵圆中心 ,偶见于基底节区等。2形态 :多为小斑片状 ,亦有点线状、小点状。 3范围 :以侧脑室三角部周围白质内发生多见 ,常同时出现于多个部位。 4时常伴有其他合并征象 ,如 ,胼胝体发育不良、畸形或脑室扩大等。结论 :MRI扩展了对儿童脑白质病变的认识 ,是一种较好的手段     

Gd-DOTA as a gastrointestinal contrast agent for gastric emptying measurements with MRI

Current MR meal markers may interfere with gastric motility and secretion restricting the use of MRI in the measurement of gastric physiology. We therefore evaluated Gd-DOTA as a liquid phase marker, in vitro by determining dissociation, and adherence to the solids, and in vivo by simultaneous MRI (0.35 T scanner, multiple T₁-weighted sections of the upper abdomen) and double indicator (perfusion marker PEG 4000, meal marker ^99mTc-DTPA) measurements of emptying and secretion, following ingestion of 500 ml 10% glucose. In vitro Gd-DOTA was stable at a pH > 2 with < 2% dissociation at 24 h during incubation with HCI. Dissociation during incubation with HCI was linearly dependent on H⁺ concentration (0.77 < pH < 2.02). Less Gd-DOTA was absorbed onto the solid phase than ^99mTc-DTPA (25% cf 36%). in vivo Gd-DOTA marked gastric contents provided strong positive contrast. Similar emptying curves were observed with both MRI and double-indicator techniques (r = 0.987, P < 0.001). Gd-DOTA has the potential to be a useful liquid phase contrast agent in MR studies on gastric function.     

Magnetic resonance elastography of the lung: technical feasibility.

Magnetic resonance elastography (MRE) is a phase-contrast technique that can spatially map shear stiffness within tissue-like materials. To date, however, MRE of the lung has been too technically challenging-primarily because of signal-to-noise ratio (SNR) limitations and phase instability. We describe an approach in which shear wave propagation is not encoded into the phase of the MR signal of a material, but rather from the signal arising from a polarized noble gas encapsulated within. To determine the feasibility of the approach, three experiments were performed. First, to establish whether shear wave propagation within lung parenchyma can be visualized with phase-contrast MR techniques, MRE was performed on excised porcine lungs inflated with room air. Second, a phantom consisting of open-cell foam filled with thermally polarized (3)He gas was imaged with MRE to determine whether shear wave propagation can be encoded by the gas. Third, preliminary evidence of the feasibility of MRE in vivo was obtained by using a longitudinal driver on the chest of a normal volunteer to generate shear waves in the lung. The results suggest that MRE in combination with hyperpolarized noble gases is potentially useful for noninvasively assessing the regional elastic properties of lung parenchyma, and merits further investigation.     

动态MRI对臂丛根性损伤和颈髓损伤的鉴别诊断意义

目的探讨动态MRI诊断臂丛神经根性损伤的影像学表现及其诊断价值，以及在与颈髓损伤的鉴别诊断中的临床意义。方法对8例臂丛神经根性损伤患者行动态MRI检查，结合CT薄层扫描和肌电图随访；所有8例患者均手术证实为臂丛根性损伤。结果本组患者在伤后早期1～2d内均无位于椎间孔及椎间孔外的创伤性脊膜囊肿、神经根断裂等支持臂丛根性损伤的MRI异常表现；4例患者有颈椎骨折或颈髓损伤的MRI表现。伤后7～15d（平均10d）后，再次行颈椎MRI检查，出现典型的MRI臂丛根性损伤表现：椎间孔及椎孔外臂丛神经走行处T2WI高信号的创伤性脊膜囊肿、脊髓移位和神经根缺失及走行异常等。结论动态MRI检查对臂丛根性神经损伤具有损伤节段定位准确、椎管外部分同样能够显示、无创、操作简单、准确性高等特点；其短期内特征性的动态变化易于诊断臂丛根性损伤，同时又能与颈髓损伤相鉴别。     

Ectopic cervico-mediastinal thymoma confirmed by flow cytometric analysis of tumor-derived lymphocytes

Ectopic cervical or cervico-mediastinal thymomas are very rare and most of them are asymptomatic, except for the presence of a cervical mass. We present the case of a 71-year-old man with an ectopic cervico-mediastinal thymoma threatening superior vena cava syndrome. He had a slight headache and presented with venous dilatation on the chest wall. A computed tomographic scan and magnetic resonance, imaging of the chest demonstrated a mass extending from the right neck to the hilum, that indented the trachea and compressed and displaced the brachiocephalic veins anteriorly. Under a right hemicollar incision and median sternotomy, the mass was resected en bloc together with the thymus. The resected specimen was an encapsulated mass measuring 11×7×4 cm. The pathological diagnosis was type AB, non-invasive thymoma, confirmed by 3-color flow, cytometry of tumor-derived lymphocytes. Flow cytometry using biopsy material may contribute to the preoperative diagnosis of ectopic thymoma.     

颅内表皮样囊肿的常规T_1WI、T_2WI、FLAIR及DWI对比分析

目的:通过定性分析和定量比较来探讨颅内表皮样囊肿(ECs)的FLAIR和DWI特征。方法:ECs16例,测量其T1WI、T2WI、FLAIR及DWI上病灶信号强度和ADC值,计算组织间对比度(CR)和对比噪声比(CNR)。结果:在FLAIR上ECs平均信号强度高于脑脊液(CSF),低于脑组织。在T1WI上,表皮样囊肿与脑脊液间的CR和CNR分别是0.11±0.06和1.02±1.11;在T2WI上,ECs与CSF间的CR和CNR分别是0.05±0.04和1.05±0.58;而在DWI上,ECs与CSF间的CR是12.56±2.87,CNR是18.23±5.42。16例患者示踪DWI图像上均呈明显高信号。ECs平均ADC值明显低于CSF(P<0.001),而高于脑白质(P=0.002)。结论:FLAIR对颅内表皮样囊肿显示优于常规MRI序列,DWI描述ECs轮廓优于其它MRI序列。