Preprocedural MR imaging for percutaneous vertebroplasty: special interest in contrast enhancement

PURPOSE: The success of percutaneous vertebroplasty (PVP) depends greatly on preprocedural evaluation of the patients. The purpose of this study was to evaluate the efficacy of preprocedural magnetic resonance imaging (MRI) for the indications of PVP. MATERIALS AND METHODS: A retrospective review of 122 osteoporotic compression fractures in 63 patients who underwent preprocedural gadolinium-enhanced MRI and PVP was performed. Based on the extent of contrast enhancement on preprocedural MRI, each case was classified into one of two groups: group 1, which represented more than 50% of the vertebral body enhanced; and group 2, which represented less than 50% of the vertebral body enhanced. The most enhancing level was evaluated in multilevel PVP sessions. We evaluated the difference of pre- and postprocedural pain scales between groups 1 and 2 using Mann-Whitney's U-test. RESULTS: There was a trend toward higher preoperative pain score in group 1, but it was not statistically significant (P = 0.0537). In addition, the postoperative pain score in group 2 was significantly higher than that in group 1 (P = 0.0007). The difference between the pre- and postoperative pain scores was significantly higher in group 1 than in group 2 (P = 0.0001). CONCLUSION: Contrast enhancement on MRI indicates a painful lesion and extensive contrast enhancement predicts better pain relief after PVP.     

MRI增强及延迟扫描在脑转移瘤诊断中的应用

目的：进一步探讨MRI T1WI增强及延迟扫描在脑转移瘤诊断中的应用。材料和方法：回顾性分析近两件来经临床或手术病理证实的48例脑转移瘤MR图像，采用平扫、增强及增强后延迟扫描，比较增强前后及延迟扫描后病灶显示情况。结果：①平扫发现病灶直接征象约占60%。②增强后除1例强化不明显外，其余47例均见不同程度和形式的强化，较平扫时更清楚显示病灶形态、大小、边界、浸润范围。有17例显示出平扫无水肿、未显示的65个病灶。③延迟8-10min扫描病灶显示更清楚者17例，比增强后即时扫描增多者10例，共28个病灶。结论：临床疑有脑转移瘤而行MRI检查的病人，增强扫描应成为常规，它能为诊断和治疗方法的选择提供更为丰富的资料，而增强后的延迟扫描，能提供更多，更全的信息，在脑转移瘤的诊断中，有一定价值。     

Polymeric gastrointestinal MR contrast agents.

Combining either paramagnetic (gadolinium chelates) or superparamagnetic (ferrite) contrast agents with polymers such as polyethylene glycol or cellulose, or with simple sugars such as dextrose, results in mixtures that exhibit improved T1 and/or T2 relaxivity compared with that of the contrast agent alone. It is suggested that the addition of such inexpensive and nontoxic polymers or saccharides may improve the effectiveness and decrease the cost of enteric contrast agents.     

Gadodiamide injection as a contrast medium for MRI of the central nervous system: a comparison with gadolinium-DOTA

The tolerance and diagnostic efficacy of a new nonionic, intravenous MRI contrast medium, gadodiamide injection (Omniscan^®) are reported and compared with those of gadolinium-DOTA after completion of a double-blind, randomized, parallel study in 60 patients using a dose of 0.1 mmol/kg. Two patients were excluded from the statistical analysis after trial entrance since no contrast medium was injected. The indications for the MRI examination were known or suspected CNS lesions. Vital signs, chemical and haematological parameters were monitored. No significant abnormalities were observed, confirming the excellent tolerance of both contrast media. The usefulness of gadolinium-containing contrast media was again documented, since in 8.6% (5/58) of the patients the lesion(s) could be seen only after injection. Contrast enhancement was seen in 87.8% (43/49) of the patients with abnormal findings, and provided additional diagnostic information in 24.5% (12/49). Lack of contrast enhancement in 12.2% (6/49) of patients with abnormal findings was a significant negative finding.     

Dynamic signal intensity changes in liver with superparamagnetic MR contrast agents.

The dynamic effects of three different superparamagnetic magnetic resonance (MR) contrast agents on liver signal were evaluated with an echo-planar imaging technique. The contrast agents were (a) USPIO (ultrasmall superparamagnetic iron oxide), which has a long blood half-life and was developed for MR imaging of lymph nodes and bone marrow; (b) AG (arabinogalactan)-USPIO, an asialoglycoprotein receptor--directed iron oxide with hepatocyte uptake; and (c) AMI-25, a conventional reticuloendothelial iron oxide agent. Dynamic liver signal intensity (SI) curves reflect different uptake mechanisms for the different agents. Receptor blocking experiments indicate that intracellular redistribution or clustering of the AG-USPIO (known to occur from electron microscopy studies) does not contribute to the decrease in liver SI. Monitoring liver SI over time with echo-planar imaging may provide a better understanding of the kinetics of the growing number of MR contrast agents and allow optimization of imaging protocols to exploit peak enhancement.     

MR spectrum in spinal dysraphism

Spinal dysraphism is a general term which encompasses a wide variety of anomalies of the spine, all of which result from imperfect midline fusion of the embryonic neural tube. This term refers to large defects that involve the spine and not to small vertical clefts commonly seen within the spinal process of L5 or S1. We present a spectrum of MR imaging findings selected from a retrospective review of 100 patients of spinal dysraphism evaluated at our institution. Received: 18 May 2000 Revised: 13 July 2000 Accepted: 13 July 2000     

颅内原发性肿瘤动态增强MRI探讨

目的：探讨动态增强ＭＲＩ对颅内原发性肿瘤的诊断价值。材料与方法：使用１．０ＭＲＩ系统（Ｍａｇｎｅｔｏｍ Ｉｍｐａｃｔ,Ｓｉｅｍｅｎｓ）ＳＥ序列对７２例颅内原发性肿瘤进行动态增强扫描,分析各种肿瘤的对比增强率－时间（ＣＥＲ－Ｔ）曲线类型、 增强峰值（ＥＰ）及最大对比增强率（ＭＣＥＲ）。结果：ＥＰ在９０秒内见于３例血管瘤型脑膜瘤、１例血管母细胞瘤及１例脉络膜乳头状瘤;２６例星形细胞瘤仅４例Ⅲ、Ⅳ级的Ｅ     

Superparamagnetic iron oxide contrast agents: physicochemical characteristics and applications in MR imaging

Superparamagnetic iron oxide MR imaging contrast agents have been the subjects of extensive research over the past decade. The iron oxide particle size of these contrast agents varies widely, and influences their physicochemical and pharmacokinetic properties, and thus clinical application. Superparamagnetic agents enhance both T1 and T2/T2* relaxation. In most situations it is their significant capacity to reduce the T2/T2* relaxation time to be utilized. The T1 relaxivity can be improved (and the T2/T2* effect can be reduced) using small particles and T1-weighted imaging sequences. Large iron oxide particles are used for bowel contrast [AMI-121 (i.e. Lumirem and Gastromark) and OMP (i.e. Abdoscan), mean diameter no less than 300 nm] and liver/spleen imaging [AMI-25 (i.e. Endorem and Feridex IV, diameter 80-150 nm); SHU 555A (i.e. Resovist, mean diameter 60 nm)]. Smaller iron oxide particles are selected for lymph node imaging [AMI-227 (i.e. Sinerem and Combidex, diameter 20-40 nm)], bone marrow imaging (AMI-227), perfusion imaging [NC100150 (i.e. Clariscan, mean diameter 20 nm)] and MR angiography (NC100150). Even smaller monocrystalline iron oxide nanoparticles are under research for receptor-directed MR imaging and magnetically labeled cell probe MR imaging. Iron oxide particles for bowel contrast are coated with insoluble material, and all iron oxide particles for intravenous injection are biodegradable. Superparamagnetic agents open up an important field for research in MR imaging.     

Spinal pilocytic astrocytoma: MR imaging findings at first presentation and following surgery

Objective

The objective of this article is to describe MR imaging findings of spinal cord pilocytic astrocytomas at first presentation and following neurosurgery and to discuss briefly some of the most common differential diagnoses.

Conclusion

MR imaging findings in medullary pilocytic astrocytomas consist generally of focal or diffuse cord-enlarging masses that are irregularly shaped, accompanied by cystic elements and hydromyelia, present different degrees of contrast enhancement, high water diffusivity and a propensity for the thoracic and cervical cord.     

Preliminary clinical trial of gadodiamide injection: a new nonionic gadolinium contrast agent for MR imaging.

The safety and efficacy of a newly developed intravenous formulation of the nonionic contrast agent gadolinium diethylenetriaminepentaacetic acid-bis(methylamide), formulated as gadodiamide injection, was investigated. In 30 patients who underwent spin-echo magnetic resonance (MR) imaging before and after contrast agent enhancement, the enhanced images had characteristics judged similar to those of images enhanced by means of available gadolinium compounds. In 15 patients, contrast agent administration was of major diagnostic help, either revealing lesions not apparent without enhancement or providing important lesion characterization. In 12 patients, the lack of abnormal enhancement patterns was important in excluding the presence of disease. In three patients, the contrast agent did not provide information additional to that obtained with the unenhanced T1- and T2-weighted images. No clinically significant changes were observed in vital signs, neurologic status, or laboratory results. The authors conclude that, in this limited series, gadodiamide injection proved to be a safe and useful MR imaging contrast agent for evaluation of the central nervous system and surrounding structures.     

Comparison of Fe-HBED and Fe-EHPG as hepatobiliary MR contrast agents.

The authors studied the biodisposition and hepatobiliary transport of two potential magnetic resonance imaging contrast agents, the iron (III) chelates of N,N'-bis(2-hydroxybenzyl)ethylene-diamine-N,N'-diacetic acid (HBED) and diastereomeric N,N'-ethylenebis(2-hydroxyphenylglycine) (EHPG). Fecal and urinary excretion (mean +/- standard deviation), respectively, of FE-59 over 7 days in rats given tracer doses of the contrast agents were 67% +/- 2% and 22% +/- 1% for Fe-59-HBED and 22% +/- 2% and 26% +/- 5% for Fe-59-EHPG. In bile duct-cannulated rats given 0.05-mmol/kg doses labeled with Fe-59, 52% +/- 8% of Fe-59 from Fe-59-HBED but only 17% +/- 3% of that from Fe-59-EHPG was excreted into the bile within 90 minutes. Bromosulfophthalein, but not taurocholate or oxyphenonium, was shown to compete with both agents for hepatobiliary transport. Enterohepatic recirculation of both agents was less than 1%.     

Clinical MR imaging of degenerative spinal disease: pulse sequences, gradient-echo techniques, and contrast agents.

DEGENERATION OF THE INTERVERTEBRAL disk is a ubiquitous process, seen at autopsy in 97% of adults by age 49 years (1). Low back pain is the most expensive health care problem in patients 20–50 years old, with $14 billion spent yearly on treatment and compensation (2). The greatest costs connected with low back pain occur in patients who have pain longer than 3 months and in those with recurrent pain episodes (3). Approximately 5.2 million people are disabled by back pain (3–5). These statistics indicate that the accurate diagnosis of back pain disease is obviously of great importance. In the diagnosis of disk degeneration and its sequelae, magnetic resonance (MR) imaging has become a key ingredient. The utility of conventional two-dimensional spin-echo MR imaging of the spine has been firmly established for extradural disease (6–8). Gradient-echo techniques have more recently been used to enhance the cerebrospinal fluid (CSF)-extradural interface in the evaluation of degenerative disease (9–13). Some of the new imaging findings and concepts regarding the use of contrast material and three-dimensional techniques in the evaluation of degenerative disease of the spine are reviewed.     

成血管细胞瘤的MRI诊断

目的 分析成血管细胞瘤的MRI表现,为手术治疗方法的选择提供依据。材料与方法 30例经手术病理证实的成血管细胞瘤患者,男16例,女14例,年龄18－64岁,平均44．6岁。除1例仅作MR平扫外,其余均作MR平扫加增强扫描。结果 在30例患者中,共发现成血管细胞瘤结节33个。发生于小脑半球15例,小脑蚓部6例,桥小脑角2例,脑干4例,发生于颈髓者2例,胸髓1例。表现为囊腔结节者20例,平扫时结节多表现为等信号,增强后结节均明显强化。表现为实质性肿块者10例,在病灶内及其周围可见较多流空血管。肿瘤的部位和边界显示得十分清楚。结论 MR扫描特别是增强扫描是评价成血管细胞瘤的最佳手段。对于明确手术切除方法具有很大价值。     

动态增强减影乳腺磁共振成像研究

目的 评估动态增强减影乳腺磁振成像对乳腺疾病MRI诊断的应用价值。材料与方法 40例临床或乳腺X线摄影提示乳腺异常的患者行动态增强乳腺MRI检查。所有病例均经手术病理证实。乳腺MRI检查首先获取脂肪抑制T2WI图像,然后用FLASH 3D序列（平扫1次,注药后5－6次）获得动态增强图像并进行减影。对比剂采用Gd-DTPA(0.1mmol/kg体重）。对部分早期显著强化病灶的减影图像行最大信号强度投影法（MIP）重建。对比分析减影图像及平扫和增强图像对病灶的显示及定性效果。结果 单独应用减影图像可显示87．5％（35／40）的病灶,对恶性病灶的显示为100％（21／21）。减影图像对病灶的范围和形态学特征的显示较平扫及增强图像更清晰、直观。减影配合MIP技术可显示病灶旁的异常血管。结论 数字减影技术是一种简便易行而有效的后处理技术,动态增强减影乳腺MR图像对乳腺疾病的MRI诊断有重要价值。     

Acute spinal cord injury: Clinical aspects and magnetic resonance imaging

With increasing use of magnetic resonance (MR) imaging in the setting of acute spinal cord injury, correlation of MR findings with pathophysiologic processes and clinical neurologic findings has become possible. In this article, we review the pathologic, clinical, and MR findings seen in spinal cord injury and summarize recent attempts to provide prognostic information and therapeutic guidelines.     

脊髓损伤的MRI诊断

本文收收集了１２４例脊髓损伤行ＭＲＩ检查者，据其ＭＲＩ所见将脊髓损伤分为五型，并对各型脊髓损伤与相应临床表现的关系，与原发脊柱损伤的关系，ＭＲＩ诊断要点以及脊柱术后改变等进行了分析，还探讨了脊髓外伤后软化、囊性变等问题。     

Currently used non-specific extracellular MR contrast media

Magnetic resonance contrast agents have demonstrated their clinical usefulness in a variety of organs for improved detection of various neoplastic, inflammatory and functional abnormalities. Gadolinium chelates are the most widely used. They are extracellular, non-specific contrast agents. Their use in many clinical indications is justified because, in conjunction with improved imaging techniques, these safe and image-enhancing contrast agents add morphologic and functional information compared with unenhanced MR images. This article describes the commercially available compounds, and summarizes their approval status on the international market regarding indications and doses. Their mechanisms of action, biodistributions, toxicities and tolerance profiles in normal and high-risk patient populations are described. Additionally, this article reviews the specific recommendations by the manufacturers for patients at risk. Finally, their main clinical applications are reviewed.     

三倍量(0.3mmol/kg)国产Gd-DTPA增强MR探查脑膜转移瘤的研究

目的 评价三倍量（０．３ｍｍｏｌ／ｋｇ）国产Ｇｄ－ＤＴＰＡ增强ＭＲ探查脑膜转移瘤的效果。材料与方法 用国产Ｇｄ－ＤＴＰＡ三倍量增强ＭＲ检查１１０例临床怀疑脑转移瘤患者。先行平扫,然后静脉注射常规量（０．１ｍｍｏｌ／ｋｇ）国产Ｇｄ－ＤＴＰＡ。注射后即刻行Ｔ１ＷＩ扫描,２０分钟后行延迟扫描。距第１次注射３０分钟后,再注射０．２ｍｍｏｌ／ｋｇ的Ｇｄ－ＤＴＰＡ,从而达到累积剂量０．３ｍｍｏｌ／ｋｇ。第２次     

Gd-DTPA-enhanced MR in thoracic disc herniations

Summary The Gd-DTPA-enhanced magnetic resonance findings in two patients with herniated thoracic intervertebral discs are reported. The first patient was a 56-year-old woman with a small subligamentous T6-7 disc herniation, slightly lateralized to the right. The second patient was a 51-year-old man with a central and right posterolateral disc herniation, including a large calcified fragment, at the T8-9 level. The nonenhanced MR examination revealed the presence of an extradural mass lesion in both patients, impinging upon the dural sac and compressing and displacing the spinal cord posteriorly. The lesion was slightly hypointense on both T1- and T2-weighted spin echo sequences. Following intravenous injection of Gd-DTPA in a dosage of 0.1 mmol/kg body weight, enhancement of the posterior longitudinal ligament was noted and triangular areas of contrast uptake were seen to occur in the epidural space above and below the herniated disc. At surgery, they were found to correspond to dilated and congested epidural veins.     

正常颈髓磁共振弥散加权成像的初步研究

目的　探讨正常人颈髓的磁共振弥散加权成像 (DWI)的可行性、技术特点及研究意义。资料与方法　对5名健康志愿者采用PhilipsGyroscanIntera 1 .5T磁共振系统 ,在平面回波成像 (EPI)基础上进行不同参数扫描 ,分析比较各自影像特点并计算平均表观弥散系数 (ADC)及相对ADC值 (RA比值 )。结果　采用层厚 5mm ,导航校正多次激发SE EPI弥散序列 (MS DWEPI)可以取得较好的颈髓DW图像 ,颈髓具有明显的各向异性 ,平行于白质纤维的弥散梯度可得到较高的ADC值。在颈髓矢状位成像测量的平均ADC值为 1 .0 6± 0 .1 3× 1 0 -3 mm2 /s(0 .86～ 1 .1 8×1 0 -3 mm2 /s) ,RA比值为 3.1 2± 0 .4 8(2 .5 6～ 5 .6 8)。结论　 1 .5T磁共振系统可以进行颈髓DWI,有望对脊髓疾病的机理研究和临床诊断提供新的帮助