MRI诊断膝关节半月板桶柄状撕裂

目的:总结分析半月板桶柄状撕裂的MRI征象和诊断价值.方法:回顾性分析146个经关节镜证实的膝关节MR图像,其中28个膝关节存在半月板桶柄状撕裂,记录如下5种MRI征象:碎块内移征、外周残半月板征、双PCL征、空领结征及双前角征,并分别计算每种征象诊断半月板桶柄状撕裂的敏感度、特异度、准确度、阳性预测值和阴性预测值.结...     

Magnetic resonance imaging of the knee menisci

MRI remains the most useful noninvasive test for diagnosis of meniscal tears. Knowledge of normal anatomy and familiarity with patterns of meniscal tears are prerequisites when interpreting MRI studies of the knee. Radiologists should pay close attention to technical factors, normal variants, and associated abnormalities to maintain high diagnostic accuracy. Details of meniscal tears should be described as to best aid in orthopedic decision-making.     

Magnetic resonance of the knee menisci and cartilage

This contribution is designed to present magnetic resonance (MR) of the menisci and cartilage to the orthopedic surgeon in a practical manner. The investigators describe those MR sequences and techniques that optimally show injury, as well as the expected morphology of the menisci. Criteria for diagnosis of meniscal tears are outlined. Common “equivocal” meniscal tear appearances are shown and strategies for resolving such equivocal cases are suggested. The difficult problem of diagnosing a meniscal remnant tear or reinjury of a repaired meniscus is covered. Finally, MR imaging of chondromalacia and osteochondral injuries is discussed.     

MRI of meniscal bucket-handle tears

Objective. A meniscal bucket-handle tear is a tear with an attached fragment displaced from the meniscus of the knee joint. Low sensitivity of MRI for detection of bucket-handle tears (64% as compared with arthroscopy) has been reported previously. We report increased sensitivity for detecting bucket-handle tears with the use of coronal short tau inversion recovery (STIR) images. Design and patients. Three hundred and twenty-seven patients who had MRI of the knee between October 1994 and December 1996 and subsequently underwent arthroscopy were included in the study. We prospectively and retrospectively reviewed the MR examinations of the 30 patients with arthroscopically proven bucket-handle tears. Each of two observers examined each scan for the three traditional findings of bucket-handle tears: a double posterior cruciate ligament sign, a flipped meniscus sign and/or a fragment in the intercondylar notch. We also assessed STIR images in the coronal plane through the menisci looking for an area of increased signal within either meniscus with a displaced meniscal fragment. Results. By using four criteria for diagnosis of meniscal bucket-handle tears, our overall sensitivity compared with arthroscopy was 93% (28 of 30 meniscal bucket-handle tears seen at arthroscopy were detected by MRI). The meniscal fragment was well visualized in all 28 cases on coronal STIR images. The double posterior cruciate ligament sign was seen in 8 of 30 cases, the flipped meniscus was seen in 10 of 30 cases and a fragment in the intercondylar notch was seen in 18 of 30 cases. Conclusion. By using four criteria for diagnosis of bucket-handle tears, overall diagnostic sensitivity of MRI compared with arthroscopy increased from the previously reported 64% to 93%. Coronal STIR images are useful for detecting small meniscal bucket-handle tears.     

MRI评价膝关节半月板的桶柄状撕裂

目的 明确5种MRI征象对膝关节半月板桶柄状撕裂的诊断价值。方法 回顾135例患者139个经关节镜证实的膝关节MR图像，其中19个存在半月板桶柄状撕裂。在均不告知关节镜结果的条件下，由2名有经验的放射医生对所有图像进行独立读片，差异协商解决。每个膝关节均记录如下5种MRI征象：双后交叉韧带征(双PCL征)、半月板翻转征、空领结征、碎块内移征和外周残半月板征。分别计算每种征象诊断半月板桶柄状撕裂的敏感度、特异度、阳性预测值、阴性预测值和准确度。结果 5种征象的诊断敏感度分布于52．6％和89．5％之间，特异度分布于83．3％和98．3％之间，阳性预测值分布于42．9％和88．2％之间，阴性预测值分布：于92．7％和98．3％之间，准确度分布于82．7％和96．4％之间。“碎块内移征”和“外周残半月板征”的诊断敏感度最高，“双PCL征”的诊断特异度和阳性预测值最高，而“碎块内移征”具有最高的阴性预测值和诊断准确度。结论 半月板桶柄状撕裂在MRI上可以有多种表现，各种征象对诊断的能力有所不同。     

Magnetic resonance imaging of the ligaments and menisci of the knee

Although the technique is still developing and the data are preliminary, MRI will likely be the best noninvasive method for evaluating the ligaments and menisci of the knee. It can provide valuable and accurate information, especially in the acutely injured knee. The presence, extent, and exact location of cruciate ligament disruption can be visualized. This is useful in patients in whom the clinical diagnosis is uncertain and provides valuable information in preoperative planning. Equally important is the ability of MRI to provide diagnostic information about associated injuries to the collateral ligaments, capsule, menisci, articular cartilage, and subchondral bone. Proper pulse sequence selection is important. T2-weighted spin-echo sequences are best for visualizing injuries to the ligaments and menisci, and T1-weighted sequences (inversion-recovery or spin-echo with a short TR and a short TE) are more helpful in evaluating cartilaginous and bony abnormalities.     

Parallel Imaging Artifacts in Body Magnetic Resonance Imaging

Objective

To familiarize the reader with the fundamental concepts of partial parallel imaging (PPI); to review the technical aspects of PPI including calibration scan, coil geometry, and field of view (FOV); and to illustrate artifacts related to parallel imaging and describe solutions to minimize their negative impact.

Results

PPI has led to a significant advance in body magnetic resonance imaging by reducing the time required to generate an image without loss of spatial resolution. Although PPI can improve image quality, it is not free of artifacts, which can result in significant image degradation. Knowledge of these artifacts and how to minimize their effect is important to optimize the use of parallel imaging for specific body magnetic resonance imaging applications.

Conclusions

The reader will be introduced to the fundamental principles of PPI. Common imaging characteristics of PPI artifacts will be displayed with an emphasis on those seen with image-based methods, the principles behind their generation presented, and measures to minimize their negative impact will be proposed.     

功能磁共振成像在中国的研究现状

本文回顾性分析中国研究机构近10年来发表的149篇有关运动、感觉、认知、临床等方面的fMRI研究论文,动态观察了中国fMRI的研究过程,总结并提出目前中国在fMRI研究中所存在的问题,探讨了我国fMRI研究发展前景.     

Magnetic Resonance Coronary Artery Imaging

Coronary artery imaging with magnetic resonance imaging carries the potential for a noninvasive, essentially risk-free screening test for those at risk for coronary heart disease. Many physiologic and anatomic challenges including cardiac and respiratory motion and the small size, tortuosity, and variable flow characteristics of the coronary arteries hamper effort to achieve this goal. This article reviews the efforts of several research groups to surmount these difficulties through the use of 2D and 3D techniques; spin echo, gradient echo, and ultrafast sequences; saturation pulses; and contrast agents. Promising results have been and continue to be reported although no obvious optimal solution has yet been determined.     

Real-Time Functional Magnetic Resonance Imaging

A recursive algorithm suitable for functional magnetic resonance imaging (FMRI) calculations is presented. The correlation coefficient of a time course of images with a reference time series, with the mean and any linear trend projected out, may be computed with 22 operations per voxel, per image; the storage overhead is four numbers per voxel. A statistical model for the FMRI signal is presented, and thresholds for the correlation coefficient are derived from it. Selected images from the first real-time functional neuroimaging experiment (at 3 Tesla) are presented. Using a 50-MHz workstation equipped with a 14-bit analog-to-digital converter, each echo planar image was acquired, reconstructed, correlated, thresh-olded, and displayed in pseudocolor (highlighting active regions in the brain) within 500 ms of the RF pulse.     

神经纤维瘤病MR影像表现

目的　分析并探讨神经纤维瘤病的分型及各型的MR影像学表现。方法　回顾性地分析 8例神经纤维瘤病患者的临床及影像学资料 ,所有病例均常规行MRI及钆剂强化扫描 ,归纳所有患者的临床表现及影像学特点。结果　根据NIH的诊断标准 ,8例中 ,4例属NF -1型 ,均在脑内胶质瘤、椎管内神经纤维瘤或脑内对称部位的异常信号基础上 ,合并有皮肤的咖啡牛乳色斑或多发神经纤维瘤 ,其中 1例有家族史 ;4例属NF -2型 ,均患双侧听神经瘤 ,2例合并髓内星型细胞瘤。结论　NF -1型在所有神经纤维瘤病中占大多数 ,且多合并有皮肤损害 ;NF -2型较少见 ,典型表现为双侧听神经瘤 ,皮损少见。MRI及强化扫描对检出神经纤维瘤病中枢神经系统的损害方面有优势