Detection of aortic arch thrombus using MR imaging

Three patients with peripheral embolization and negative echocardiographic examinations were studied with MR imaging. Magnetic resonance imaging detected aortic arch thrombi in the absence of aortic aneurysm, dissection, or ulcerated plaques. By combining spin echo and cine MR sequences, MR enabled us to characterize and contrast intravascular mural thrombi reliably without application of contrast media. Thus we are assisted in the identification of patients at risk for embolization from an often overlooked source: the thoracic aorta.     

应用ROC曲线评价DWI诊断直肠癌的价值

目的应用受试者工作特征曲线(ROC曲线)评价DWI对直肠癌的诊断价值。方法选取60例经病理证实的直肠癌患者,所有患者术前均行高分辨MRI扫描检查,同时采用b值为600、1000 s/mm2对其进行弥散加权成像(DWI)检查,并计算直肠癌瘤体的表观弥散系数(ADC)值;选取15例非直肠癌患者作为对照组,并计算对照组直肠壁的ADC值。结果单独使用高分辨MRI及高分辨MRI联合DWI对直肠癌诊断的ROC曲线下面积分别为0.879、0.988;高分辨MRI结合DWI诊断直肠癌的灵敏度、特异度分别为90%,100%;同一b值下直肠癌瘤体的ADC值与对照组直肠壁比较有显著性差异(P<0.05),并确定不同b值下诊断直肠癌的最佳ADC阈值(1.856×10-3 mm/s2、1.560×10-3 mm/s2)。结论 ROC曲线评价显示DWI联合高分辨MRI对直肠癌具有较高的诊断准确度,DWI可以作为诊断直肠癌的重要补充序列。     

平山病屈颈位磁共振扫描技术研究

目的:探讨平山病屈颈位磁共振扫描技术成功的关键。方法:对6例临床确诊平山病患者行屈颈位磁共振扫描,采用GE 1.5T HD扫描系统,CTL线圈。均行两次屈颈位MR扫描(传统过屈位:患者单纯颈部垫楔形物;优化的过屈位:颈部垫楔形物同时要求患者收下颌),比较两次硬膜外腔宽度,对比分析流空血管的显示情况。结果:优化的屈颈扫描硬膜外宽度明显大于传统的屈颈扫描(P<0.05),两者存在显著性差异;流空血管的显示,传统的屈颈扫描3例,优化的屈颈扫描5例。结论:在平山病屈颈位磁共振扫描技术中,收下颌是扫描成功的关键,能清楚显示扩张的硬膜外腔和流空的异常血管。     

菲立磁增强MRI对局灶性肝病的诊断价值:与螺旋CT对比的ROC曲线分析

目的 :对比分析菲立磁增强扫描与螺旋CT增强扫描对局灶性肝病的诊断价值。方法 :收集经本院完成螺旋CT增强扫描及菲立磁增强MRI扫描且临床、手术病理证实局灶性肝病 2 6例 5 7个病灶 ,采用分组盲法ROC曲线分析对比评价菲立磁增强MRI与螺旋CT增强扫描对局灶性肝病的诊断价值。结果 :联合分析平扫 +菲立磁增强MRI对病灶检出最好 ,与其它三组比较有显著性差异。对病灶定性 ,平扫 +菲立磁增强MRI组ROC曲线下面积Az 值最大为 0 92 6 0 ,准确性为 86 .8% ,差异有显著性 ,P <0 .0 5。螺旋CT增强扫描、MRI平扫及单独分析菲立磁MRI等三种方法之间差异无显著性 (P >0 .0 5 )。结论 :菲立磁增强MRI肝成像无论病灶的检出及定性诊断价值均高于螺旋CT增强扫描。联合分析平扫+菲立磁MRI较单独分析SPIO能明显改善病灶的检出能力及定性诊断能力。     

Inferior vena cava tumor thrombus: demonstration by Gd-DTPA enhanced MR

This report demonstrates the capability of magnetic resonance imaging to determine the extent of inferior vena cava thrombi and to differentiate tumor thrombus from blood clot with the use of Gd-diethylenetriamine pentaacetic acid as a contrast agent.     

Differentiation of intraductal papillary mucinous neoplasms from other pancreatic cystic masses: comparison of multirow-detector CT and MR imaging using ROC analysis

PURPOSE: To compare the diagnostic performance of multirow-detector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the differentiation of intraductal papillary mucinous neoplasms (IPMNs) from other pancreatic cystic masses. MATERIALS AND METHODS: A total of 53 patients with pathologically proven pancreatic cystic lesions who had undergone MDCT and MRI were included in this study. Two radiologists analyzed the morphologic features of the lesions and graded the lesion conspicuity on each examination. The readers assigned their confidence level regarding the differentiation of IPMN from other lesions and predicting ductal communication of the lesion. The radiologists' diagnostic confidence was compared using receiver operating characteristic (ROC) analysis. RESULTS: The Az values for each observer for predicting ductal communication of the lesion and differentiating IPMN from other lesions were as follows: For MRI they were respectively 0.949 and 0.995 for reader 1, and 0.916 and 0.932 for reader 2. For MDCT they were respectively 0.790 and 0.875 for reader 1, and 0.774 and 0.850 for reader 2. In addition, for differentiating IPMNs from other lesions, MRI was significantly more accurate than MDCT (P < 0.05) for one observer, but for the other observer there was no significant difference between the two examinations (P = 0.059). For predicting ductal communication of the cystic lesions for both observers, MRI was significantly more accurate than MDCT (P < 0.05). The weighted kappa values indicate good agreement (kappa = 0.61) between observers for MDCT, and excellent agreement (kappa = 0.82) for MRI. CONCLUSION: Pancreatic MRI shows better diagnostic performance than MDCT for differentiating IPMNs from other cystic lesions of the pancreas.     

仿真胃镜与钡餐比较评价胃部溃疡性病灶:ROC曲线分析

目的：与上消化道钡餐(UGl)比较研究CT仿真胃镜(CTVG)对胃部溃疡性病变诊断的价值。方法：经胃镜证实为溃疡性病变的患者39例，手术病理证实29例为胃癌，10例为良性溃疡。所有患者均在3天内行螺旋CT及UGI检查，两位阅片者对所有的CTVG及UGI图像进行主观性盲法阅片。图像质量的评价分3级，检出的可信度、良恶性溃疡的鉴别及恶性溃疡分型的鉴别评价分5级，后两项采用ROC曲线进行分析。结果：两位阅片者均认为对于图像质量、病灶检出率、溃疡病灶的良恶性鉴别，CTVG与UGI类似(P＞0.05)；对于溃疡型胃癌分型的准确性，CTVG明显优于钡餐(P＜0．05)。结论：CTVG对溃疡型胃癌分型的判断优于UGI，但对溃疡病灶的良恶性鉴别，CTVG与UGI无明显差异；胃部螺旋CT扫描是一种简便、有效的检查方法，值得进一步研究。     

ROC curve analysis of lesion detectability on phantoms: comparison of digital spot mammography with conventional spot mammography

Although conventional screen--film mammography has excellent spatial resolution and is commonly used as a screening tool, certain inherent limitations prevent its further improvement. New digital mammography techniques, despite lower spatial resolution than screen--film mammography, may overcome these limitations. This study compared lesion detectability between charge coupled device-based digital spot mammography and conventional spot mammography. A total of 100 sets of images of specially designed breast phantoms was acquired, with variable background achieved by overlapping several layers of grapefruit fibre on a 4 cm thick lucite slab, using both modalities. 75 sets were "normal" images and 25 sets were images with simulated lesions. Four radiologists assessed the images according to a five-point confidence scale. The results were used to construct receiver operating characteristic curves. No statistical difference was observed between the two sets of curves for individual radiologists as well as pooled data. The lower spatial resolution of digital mammography was compensated for by its higher contrast sensitivity relative to conventional spot mammography.     

Retroaortic renal vein with tumor thrombus: MR findings

The magnetic resonance (MR) findings in a case of tumor extension into a retroaortic renal vein from a renal cell carcinoma are reported. The signal characteristics of the tumor thrombus paralleled those of the renal mass, and the preoperative recognition of the anomalous vessel lead to an altered surgical approach.     

Cardiac tumors and thrombus: evaluation with MR imaging

Thirty patients with a suspected cardiac or pericardial mass underwent MR imaging. Twenty-six also had two-dimensional (2D) echocardiography, and three also had CT; one patient had MR only. Overall, 18 (60%) of the 30 patients were found to have a mass lesion. The lesion was confirmed by biopsy, surgery, or unequivocal demonstration on CT, 2D echocardiography, and/or MR imaging. Fourteen of the lesions were soft-tissue or tumor masses, and four were thrombi. The findings on 2D echocardiography and MR were in agreement in 17 (65%) of 26 patients who had both studies. MR was equivocal or in error in two patients (7%), and 2D echocardiography was nondiagnostic in seven (27%). In all seven patients with equivocal 2D echocardiography, the diagnosis was made by MR. In the four patients who did not have 2D echocardiography, MR showed the mass clearly. MR imaging is useful in the diagnosis of cardiac mass lesions. It can be used effectively in addition to 2D echocardiography to increase the certainty of diagnosis, and it is useful when 2D echocardiography is equivocal or inadequate.     

Prediction of illness severity in patients with major depression using structural MR brain scans

Purpose:

To develop a model for the prediction of Major Depressive Disorder (MDD) illness severity ratings from individual structural MRI brain scans.

Materials and Methods:

Structural T1‐weighted MRI scans were obtained from 30 patients with MDD recruited from two different scanning centers. Self‐rated (Beck Depression Inventory; BDI), and clinician‐rated (Hamilton Rating Scale for Depression, HRSD), syndrome‐specific illness severity ratings were obtained just before scanning. Relevance vector regression (RVR) was used to predict the scores (BDI, HRSD) from T1‐weighted MRI scans.

Results:

It was possible to predict the BDI score (correlation between actual score and RVR predicted scores r = 0.694; P < 0.0001), but not the HRSD scores (r = 0.34; P = 0.068) from individual subjects. BDI scores from the most ill patients were predicted more accurately than those from patients who were least ill (standard deviation of difference between predicted and actual scores 2.5 versus 7.4, respectively).

Conclusion:

These data suggest that T1‐weighted MRI scans contain sufficient information about neurobiological change in patients with MDD to permit accurate predictions about illness severity, on an individual subject basis, particularly for the most ill patients. J. Magn. Reson. Imaging 2012;35:64‐71. © 2011 Wiley Periodicals, Inc.     

Anatomical interpretation of MR scans of the brain

A stereotactic method of brain localization is applied to magnetic resonance imaging for the interpretation of brain structures. This proportional grid system developed by Talairach is based on two intracerebral structures, the anterior and posterior commissures. It takes into account individual variations in brain size and shape. In an experimental study on cadavers we demonstrated that his system permitted accurate identification of cortical structures on CT scan. In this paper, we describe its application to MR. It provides, on a routine basis, a simple reliable method of anatomical interpretation. The use of this grid system is made easier by the fact that both commissures are seen on midsagittal MR scans.