原发性胸腺癌的CT表现及鉴别诊断

目的分析原发性胸腺癌的影像表现,以期进一步提高对该肿瘤的认识及诊断水平。方法回顾性分析19例经病理证实的原发性胸腺癌的影像表现,17例行CT平扫及增强检查,2例仅行CT平扫检查。结果19例胸腺癌中,鳞状细胞癌16例,未分化癌、粘液表皮样癌及淋巴上皮样癌各1例;CT表现为前中上纵隔较大分叶状软组织肿块,最大径约为3.5~12.8cm(平均为6.6cm),肿块密度不均匀,均有坏死,其中3例鳞状细胞癌有钙化;19例肿瘤中,侵犯大血管10例,心包侵犯9例,胸内转移(纵隔淋巴结转移11例,胸膜转移7例,肺内转移4例),胸外转移(腹膜后淋巴结及骨骼各2例,肝脏3例)。结论原发性胸腺癌是一种罕见的纵隔肿瘤,CT表现具有一定的特征,结合病变的临床及CT表现,可提高病变的诊断率。     

Time-resolved contrast-enhanced 3D MR angiography

An MR angiographic technique, referred to as 3D TRICKS (3D time-resolved imaging of contrast kinetics) has been developed. This technique combines and extends to 3D imaging several previously published elements. These elements include an increased sampling rate for lower spatial frequencies, temporal interpolation of k-space views, and zero-filling in the slice-encoding dimension. When appropriately combined, these elements permit reconstruction of a series of 3D image sets having an effective temporal frame rate of one volume every 2-6 s. Acquiring a temporal series of images offers advantages over the current contrast-enhanced 3D MRA techniques in that it i) increases the likelihood that an arterial-only 3D image set will be obtained, ii) permits the passage of the contrast agent to be observed, and iii) allows temporal-processing techniques to be applied to yield additional information, or improve image quality.     

Ex Vivo Evaluation of Ferromagnetism,Heating, and Artifacts of Breast Tissue Expanders Exposed to a 1.5-T MR System

Three breast tissue expanders were evaluated for compatibility with MR imaging (1.5 Tesla). The metallic components of the breast tissue expanders were shown to be nonferromagnetic, heating .2°C and the artifacts varied. These results indicate that MR procedures may be performed safely in patients with these implants; however, artifacts may obscure Implant leaks or breast lesions if located near and metal portion of the breast tissue expanders.     

Virtual MR arthroscopy of the wrist joint: a new intraarticular perspective

Objective The aim of this study is to investigate whether virtual MR arthroscopy could be used to visualize the internal architecture of the radiocarpal compartment of the wrist joint in comparison to surgical arthroscopy.Design Diluted paramagnetic contrast material was injected into the radiocarpal compartment prior to MR examination in all patients. A fat-suppressed T1-weighted three-dimensional fast spoiled gradient echo sequence was acquired in addition to our standard MR imaging protocol in each patient. Three-dimensional data sets were then transferred to an independent workstation and were postprocessed using navigator software to generate surface rendered virtual MR arthroscopic images.Patients Nineteen patients referred for chronic ulnar-sided wrist pain were evaluated with conventional MR arthrography prospectively.Results and Conclusion Virtual MR arthroscopic images demonstrating the triangular fibrocartilage complex (TFCC) in an intraarticular perspective were achieved in 12 out of 19 patients. Our preliminary investigation suggests that although it has several limitations, virtual MR arthroscopy shows promise in visualizing the TFCC from an intraarticular perspective.     

Conventional and diffusion-weighted MR imaging of intracranial tuberculomas. A case report

 Intracranial tuberculoma is a rare form of central nervous system tuberculosis. We here report on conventional and diffusion-weighted cranial MR images of a non-immunocompromised patient with multiple intracranial tuberculomas, tuberculous lymphadenitis and pulmonary tuberculosis. Conventional MR imaging revealed multiple ring-enhancing mass lesions. At follow-up MR, appearances of both edema and number and size of nodules were decreased. Diffusion-weighted MR was normal and normal ADC values were found in this case of tuberculomas.     

MR microscopy of hyaline cartilage: current status

Cartilage degenerative diseases, such as osteoarthritis, affect million of people. Magnetic resonance imaging is presently the most accurate imaging modality in evaluating the state of hyaline cartilage; however, clinical MRI does not accurately reveal early degenerative alterations in cartilage, due mainly to low spatial resolution. Magnetic resonance microscopy (MRM, or microMRI) appears exceptionally well suited to the in vitro or ex vivo study of this heterogeneous tissue, due to its high spatial resolution; however, despite this, further studies are necessary to evaluate the potential of MRM in the detection of early cartilage damage. Herein we briefly review the current applications of MRM in the study of hyaline cartilage. In particular, we review the MR appearance of hyaline cartilage on high-resolution images, the different MRM techniques used to image normal and enzymatically or chemically degraded cartilage and the potential use of contrast agents. The future directions and the relevance of MRM findings for a better understanding of cartilage physiology in health and disease are also discussed.     

Coarctation of the aorta: comparison of aortic dimensions between conventional MR imaging, 3D MR angiography,and conventional angiography

Magnetic resonance angiography is increasingly used as a non-invasive method in the evaluation of coarctation of the aorta. The aim of this study was to compare aortic dimensions calculated by MR angiography and those obtained by more conventional MR sequences and conventional angiography. Twenty-six consecutive patients with coarctation underwent three-dimensional MR angiography. Two independent observers retrospectively evaluated three aortic segments, site of coarctation, presence of aneurysm and existence of collateral circulation. Three aortic segments were also compared with those obtained on classical MR sequences and conventional angiography. The MR angiography was successfully performed in all showing 1 aneurysm and collateral circulation in 8 patients. Almost perfect intraobserver ( r(2)>0.91) and excellent interobserver ( r(2)>0.80) reliabilities were obtained for each aortic segment no matter which MR sequence was employed. Similarly, mainly excellent ( r(2)>0.80) concordance analysis was observed between MR angiography measurements and those calculated by either spin-echo/gradient-echo sequences or conventional angiography. This study demonstrates that MR angiography is a fast, accurate and reproducible method in the evaluation of coarctation of the aorta. It provides excellent anatomic information and reliably detects collateral vessels. Magnetic resonance angiography could probably replace the conventional angiography and will provide an additional diagnostic value in combination with turbo spin-echo sequence.     

海绵状血管瘤的MRI表现及分析

目的:通过分析海绵状血管瘤在磁共振成像和磁共振血管成像上的表现,总结海绵状血管瘤的诊断要点。材料和方法:分析43例海绵状血管瘤的发病部位,病灶的T_1加权像和T_2加权像的表现以及MRA的表现。结果:海绵状血管瘤在T_2加权像上表现为“铁环征”;在T_1加权像上表现为高低信号的混杂影,并且大部分可观察到血管状断面的低信号;在MRA上病灶表现为节结状的、与正常血管无关系的高信号影。结论:由于MR的信号能够特异地反映海绵状血管瘤的结构,它是目前诊断该病的最佳手段。     

纵隔节细胞神经瘤的影像特点

目的 探讨纵隔节细胞神经瘤的影像表现,提高该病诊断的准确性.方法 回顾性分析8例经手术病理证实的纵隔节细胞神经瘤的影像资料.结果 肿瘤可发生于前中后纵隔,以后纵隔多见(6例),临床症状多不明显.x线平片示纵隔影增宽,密度均匀,边缘清楚.CT检查7例,其中平扫3例,见肿瘤沿冠状面偏向一侧生长,有完整包膜,多数呈均匀低密度,偶见散在钙化;平扫加增强4例,可见轻度均匀强化,也可见不均匀斑片状强化,瘤体较大时包绕血管问隙呈嵌入性生长,但与血管间隙分界清楚.MRI平扫1例,T1WI呈均匀等信号,T2WI呈均匀高信号,多平面重组可以进一步观察病变与周围血管及器官的关系.结论 纵隔节细胞神经瘤影像表现具有特征性,有助于术前正确诊断及术式的选择.     

Dual-Echo Interleaved Echo-Planar Imaging of the Brain

An interleaved echo-planar imaging (EPI) technique is described that provides images from 20 sections of the brain at two echo times (27 and 84 ms) in 1:05. Six echoes per image per repetition are collected in 24 repetitions of the pulse sequence. MR images of the brain obtained from five volunteers using the dual-echo EPI sequence, fast spin-echo (FSE), and conventional dual-echo spin-echo were evaluated qualitatively for diagnostic use and quantitatively for relative signal-to-noise ratio (SNR), contrast, and contrast-to-noise ratios (CNR).     

Preoperative local MRI-staging of patients with a suspected pancreatic mass

The aim of this study was to define the value of MRI of the pancreas for preoperative local staging of patients with a suspected pancreatic mass. Ninety-four patients (41 women, 53 men; age range 32-87 years) with a suspected pancreatic tumor underwent preoperative staging with MRI on a 1.5-T system. The MRI protocol included breath-hold MR cholangiopancreatography in turbo spin-echo technique, biphasic contrast-enhanced 3D MR angiography, and MRI of the upper abdomen with breath-hold T2-weighted half-Fourier acquired single-shot turbo spin-echo and T1-weighted fast-low-angle-shot (pre- and postcontrast) sequences. Data were collected prospectively and analyzed by two radiologists in agreement modality. Evaluation criteria were vascular involvement, resectability, and a characterization benign vs malignant. Results were compared to histopathology in 78 patients. Sixteen patients were followed-up. In 74 of 94 patients a solid tumor or an inflammation of the pancreas ( n=62) or the papilla ( n=12) was detected. In this group, MRI had a sensitivity of 98%, a specificity of 92%, and an accuracy of 96% in the characterization of malignant tumors. Regarding only the solid tumors, the positive predictive value of MRI was 87% with respect to resectability. Other pathologic findings included adenoma or inflammation of the duodenum ( n=5), carcinoma or benign stenosis of the choledochus duct ( n=7) and carcinoma of the gall bladder ( n=2). In 6 patients MRI did not depict any pathologic findings, and follow-up confirmed this interpretation. Magnetic resonance imaging allows a local preoperative staging in patients with suspected pancreatic tumor. Limitations, however, concern to the diagnostics of peritoneal and/or liver metastases.     

MR spectroscopy detection of lactate and lipid signals in the brains of healthy elderly people

Magnetic resonance spectroscopy was used to assess the presence of brain lactate and lipid signals, frequently associated with the presence of pathology, in healthy persons of 60-90 years old (n = 540). Lactate and lipid signals were observed in, respectively, 25 and 6% of women, and 18 and 2% of men. Upon adjustment for age, and for MRI-detected cerebral atrophy and white matter lesions, the gender differences in lactate and lipid remained the same (p = 0.05 and p = 0.03, respectively). Brain lactate and lipid signals appear to be intrinsic to aging. However, the presence of these metabolites in very focal areas only, rather than in any distributed fashion within the brain (the latter generally the case with cerebral atrophy and white matter lesions), strongly suggests the existence of asymptomatic focal pathology not shown on MRI.     

MR imaging: acronyms and clinical applications

The intention of this article is to provide an overview of all MR imaging techniques that are accessible on most of commercially available scanners and have the potential to be used in routine clinical applications. The techniques implemented by the major vendors are briefly explained, including a comparison of the commonly used acronyms. A classification scheme is introduced which provides a reasonable illustration of similarities and differences between various techniques. The imaging techniques are divided into two main groups, the spin-echo and gradient-echo sequences. Within each group is the basic sequence, those which require a preparation of the magnetization, those which use multiple echoes to fill the k-space and those which are performed in a single shot. For each technique the typical clinical applications are listed or the potential applications which have been published. Received: 18 August 1998; Revision received: 3 November 1998; Accepted: 4 November 1998     

Shoe rim and shoe buckle pseudotumor of the ankle in elite and professional figure skaters and snowboarders: MR imaging findings

Objective To review MR imaging of figure skaters and snowboarders presenting with painful soft-tissue swelling of the lateral supramalleolar region with a clinical provisional diagnosis of soft-tissue tumor.Design and patients MR imaging was prospectively reviewed by two sub-specialized musculoskeletal radiologists. The findings were correlated with a second clinical review and examination of the shoe wear. The patients were four female athletes undergoing heavy training regimes, ranging in age between 16 and 25 years. Two patients were elite figure skaters, and two were professional snowboarders. Three patients had unilateral masses with pain, and one patient presented with bilateral clinical findings.Results MR imaging showed subcutaneous, focal soft-tissue masses of the supramalleolar region in five ankles at the same level above the ankle joint. MR imaging prompted a second clinical review and correlation with the shoe wear. The MR imaging findings correlated to the level of the shoe rim or shoe buckle in all patients, confirming the suspected MR imaging diagnosis of an impingement syndrome. All four sportswomen were training excessively, ignoring safety advice regarding training duration, timing of breaks, and shoe wear rotation.Conclusion Ice skaters and snowboarders may present with persistent and disabling pain. On MR imaging, this corresponds to a focal soft-tissue abnormality, which may be due to subcutaneous fat impingement between the fibula and the shoe rim or shoe buckle.     

3.0T磁共振脑转移瘤IVIM与MR灌注加权成像的相关性研究

目的初步探讨利用体素内不一致运动磁共振成像(introvoxelincoherent motion MR imaging,IVIM-MRI)评价脑转移瘤的灌注,并与灌注加权成像(perfusion weighted Imaging,PWI)的指标进行相关性评价。方法收集在本院2012年6月~2012年12月间26例经手术证实的不同类型癌症发生脑转移的患者行MRI增强检查。扫描序列包括IVIM及PWI。选取颅内转移病灶共60个,应用工作站后处理软件分别测定瘤体及对侧Slow ADC(SADC)、Fast ADC(FADC)、Fraction of FastADC(FFADC)和血流量(cerebral blood flow,CBF)、血容量(cerebral blood volume,CBV),并计算出各个参数的相对值(r),即:r值=(实质病灶值/对侧正常值)×100%。将瘤体与正常侧的IVIM指标进行统计学比较,并将IVIM与PWI的各参数进行Pearson相关性分析。对IVIM和PWI的参数进行转移瘤诊断的ROC分析。结果转移瘤的SADC为(0.437±0.023)×10-3 mm2/s),其对侧脑组织的SADC为(0.223±0.010)×10-3 mm2/s),两者间差异有统计学意义(t=4.83,P0.01);转移瘤的FADC为(3.65±0.11)×10-3 mm2/s),其对侧脑组织的FADC为(2.27±0.12)×10-3 mm2/s),两者间差异有统计学意义(t=8.36,P0.05);转移瘤的FFADC为441.67×10-3±21.19×10-3,其对侧脑组织的FFADC为276.5×10-3±8.07×10-3,两者间差异有统计学意义(t=7.28,P0.01)。转移瘤的rFADC为5.57±31.66,rCBV为2.79±1.27,Person相关性分析显示rFADC与rBV呈弱相关(r=0.274,P0.05),而rFFADC、rSADC与rCBF、rCBV无明显相关性。FADC、FFADC、SADC、CBF、CBV的ROC曲线分析显示,AUCFADC=0.924(P=0.025);AUCFFADC=0.860(P=0.034);AUCSADC=0.896(P=0.030);AUCCBF=0.849(P=0.035);AUCCBV=0.865(P=0.034)。FADC的ROC曲线的AUC最大,诊断准确性更高。结论 IVIM的参数测量能反映转移瘤的灌注特性,但是由于与PWI的技术原理不同,灌注的测量指标之间只具有弱相关性。     

Dynamic breast magnetic resonance imaging without complications in a patient with dual-chamber demand pacemaker

Mammography and ultrasound indicated a cancer of the right breast in a 77-year-old woman with a dual-chamber demand pacemaker. The patient was not pacemaker-dependent. She underwent breast 1.5T magnetic resonance imaging (MRI) (dynamic gradient echo sequence with Gd-DOTA 0.1 mmol/kg). Before the patient entered the MR room, the configuration of the device was changed (the response to magnet was switched from asynchronous to off and the rate-responsive algorithm was disabled). No relevant modifications of heart rhythm or rate were observed during the MR examination. No symptom was reported. Immediately after the examination, the pacemaker interrogation showed neither program changes nor alert warnings. MRI detected a bifocal cancer in the right breast which allowed tailored breast-conserving treatment to be initiated. Histopathology confirmed a bifocal invasive ductal carcinoma.