舌根异位甲状腺的CT和MRI表现

目的 探讨舌根异位甲状腺的CT和MRI表现. 方法 回顾性分析8例经核素扫描或手术证实的舌根异位甲状腺患者的CT或MRI资料,其中6例接受颈部CT检查,2例接受颈部MR检查. 结果 8例病灶均位于舌根中线区,6例呈类圆形,2例呈分叶状,边界清楚,最大径16～36 mm,平均24 mm.与舌根肌肉比较,2例CT平扫呈高密度,其中1例密度不均匀;5例增强后明显强化,其中2例病灶内有散在的小囊状低密度区;3例病变密度不均匀,结合其他检查考虑伴发结节状甲状腺肿,其中1例经病理证实.2例MR T1WI、T2WI均呈较高信号,增强后明显强化,病变信号较均匀.颈部均未发现正常位置的甲状腺. 结论 舌根中线区高密度或高信号并明显强化的结节是舌根异位甲状腺的特征性影像学表现,密度或信号不均匀常提示其发生病变;结合颈部无正常位置甲状腺,比较容易作出诊断.     

Improvements in PET Image Quality in Time of Flight (TOF) Simultaneous PET/MRI

Purpose

An integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) scanner with time of flight (TOF) technology is now available for clinical use. The aim of this study is to evaluate the potential of TOF PET in PET/MRI to reduce artifacts in PET images when compared to non-TOF PET/MRI, TOF PET/X-ray computed tomography (CT), and non-TOF PET/CT.

Procedures

All patients underwent a single 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) injection, followed first by PET/CT, and subsequently by PET/MRI. PET/CT exams were requested as standard-of-care for oncological indications. Using the PET acquisitions datasets, 4 series of images (TOF PET/CT, non-TOF PET/CT, TOF PET/MRI, and non-TOF PET/MRI) were reconstructed. These image series were visually evaluated for: (1) dental metal artifacts, (2) breathing artifacts, and (3) pelvic artifacts due to scatter correction errors from high bladder [¹⁸F]FDG concentration. PET image quality was assessed by a 3-point scale (1—clinically significant artifact, 2—non clinically significant artifact, and 3—no artifact).

Results

Twenty-five patients (mean?±?SD age: 56?±?13 years old; female: 10, male: 15) were enrolled. TOF PET/MRI, non-TOF PET/MRI, TOF PET/CT, and non-TOF PET/CT scores 2.8, 2.5, 2.4, and 2.3, respectively for the presence of dental artifacts, 2.8, 2.5, 2.2, and 1.9, respectively, for the presence of breathing artifacts, and 2.7, 1.7, 2.0, and 1.3, respectively, for the presence of pelvic artifacts TOF PET/MRI images showed the highest image quality scores among the 4 datasets of PET images.

Conclusion

The superior timing resolution and resulting TOF capability of the new PET/MRI scanner improved PET image quality in this cohort by reducing artifacts compared to non-TOF PET/MRI, TOF PET/CT, and non-TOF PET/CT.

     

Magnetic resonance imaging for vertebral-basilar system infarction

The rehabilitative course for patients who have suffered vertebral-basilar vascular lesions is often interrupted by intermittent episodes of increasing dizziness, nausea, vomiting, and ataxia. Since CT studies of the brain do not always visualize these lesions reliably, the rehabilitation specialist has been without a diagnostic tool to distinguish between progressive and stable vertebral-basilar system infarctions. Magnetic resonance imaging (MRI) offers a safe, noninvasive, sensitive means of monitoring vascular lesions in the posterior fossa. The purpose of this study was to use MRI to evaluate patients with suspected vertebral-basilar vascular lesions. In three patients studied, MRI was superior to CT scan. Advantages of MRI included lack of artifact due to bone scattering from ionizing radiation, ability to image directly in the sagittal plane, visualization and localization of pathologically smaller lesions, and potential for performing serial studies without exposing patients to large doses of radiation. In each case, MRI data yielded valuable adjunctive information that aided further rehabilitation evaluation and management. We conclude that MRI may be a useful diagnostic and prognostic tool in evaluating and managing rehabilitation patients with vascular lesions involving the vertebral-basilar system.     

Chiari畸形的MR,CT诊断（附42例报告）

目的：评价磁共振及CT对Chiari畸形的诊断价值。材料与方法：收集42例资料完整的Chiari畸形患者磁共振成像资料,其中21例做了头颅CT扫描,9例做了颈椎CT平扫。结果：I型35例,I型7肽1型的主要征象是小脑扁桃体下移,Ⅱ型的小脑扁桃体下移程度更为严重,可达颈2～3椎体水平椎管内,并伴有脑干、四脑室移位变形及脑积水等,常合并其它颅底发育异常。结论：MRI无骨伪影,高组织对比．可多方位扫描,便于测量,矢状位薄层扫描TI加权像即可满足诊断需要。MRI的应用使本病的诊断变得简单可靠。     

运用超声检查对原发性舌癌诊断的应用价值

原发性舌癌发病率高,在口腔颌面部肿瘤中居首位,浸润性强,恶性程度大,早期即可伴颈部淋巴结转移,因此早期诊断对提高患者生存质量、较少病死率具有重要意义,超声检查可以发现舌癌病灶尤其是不易被CT及MRI检出的小舌癌,对原发性舌癌及颈部淋巴结转移具有重要价值。本文旨在对超声在原发性舌癌诊断中的应用价值作一综述。     

Computed tomographic evaluation of surgical clip artifact: Tissue phantom and experimental animal assessment

Surgical clips in postoperative patients create streak artifact on computed tomographic (CT) studies which often significantly degrade image quality. We have evaluated three types of surgical clips: tantalum, stainless steel, and titanium in a phantom and animal model to assess their relative CT artifact. Tantalum clips showed the greatest artifact, stainless steel intermediate, and titanium the least artifact. Artifact could be reduced with the use of faster scan times. The type of clip used may enter into surgical decision making depending upon the need for high resolution scanning to detect small pathological processes in the area of surgical clips.     

Partial ring artifact on cardiac CT: image presentation and clinical implication

In computed tomography (CT), the term “artifact” is applied to any systematic discrepancy between the CT numbers in the reconstructed image and the true attenuation coefficients of the object. A partial ring artifact in cardiac CT has a unique pattern and has not been previously reported in real clinical practice. In this report, we will demonstrate the images and animations of a cardiac CT which is affected by a partial ring artifact due to a broken detector module. The different characteristics of ring artifacts on routine and cardiac CT, and the implications for clinical interpretation will also be described. In summary, when a partial ring artifact is noted incidentally on cardiac CT, we suggest interpreting the images by reviewing reconstructed images from different RR-intervals to avoid unnecessary repeated scans and additional radiation exposure.     

Complete artifact removal for EEG recorded during continuous fMRI using independent component analysis

The simultaneous recording of EEG and fMRI is a promising method for combining the electrophysiological and hemodynamic information on cerebral dynamics. However, EEG recordings performed in the MRI scanner are contaminated by imaging, ballistocardiographic (BCG) and ocular artifacts. A number of processing techniques for the cancellation of fMRI environment disturbances exist: the most popular is averaged artifact subtraction (AAS), which performs well for the imaging artifact, but has some limitations in removing the BCG artifact, due to the variability in cardiac wave duration and shape; furthermore, no processing method to attenuate ocular artifact is currently used in EEG/fMRI, and contaminated epochs are simply rejected before signal analysis. In this work, we present a comprehensive method based on independent component analysis (ICA) for simultaneously removing BCG and ocular artifacts from the EEG recordings, as well as residual MRI contamination left by AAS. The ICA method has been tested on event-related potentials (ERPs) obtained from a visual oddball paradigm: it is very effective in attenuating artifacts in order to reconstruct clear brain signals from EEG acquired in the MRI scanner. It performs significantly better than the AAS method in removing the BCG artifact. Furthermore, since ocular artifacts can be completely suppressed, a larger number of trials is available for analysis. A comparison of ERPs inside the magnetic environment with those obtained out of the MRI scanner confirms that no systematic bias in the ERP waveform is produced by the ICA method.     

超声、CT/MR在舌鳞状细胞癌诊断中的价值

目的比较超声检查和CT、MR在舌鳞状细胞癌诊断中的价值。方法对26例原发性舌癌、12例复发性舌癌术前同时行超声和CT/MR检查,对比观察肿块以及颈部淋巴结的情况。结果超声与CT/MR比较可知口腔内超声对于小病灶的检出率以及颈部淋巴结转移阳性的检出率大于CT和MR,而CT和MR对于侵犯周围组织及骨骼的评估要优于超声。结论超声可作为术前诊断和术后随访的首选方法,而对于侵袭范围较广且疑有骨质破坏的病例,可在超声的基础上再加行CT或者MR检查。     

Oral cavity cancer

The oral cavity is anterioly located and unique in the variety of tissues contained in this area. Although oral cancer screening may be done on clinical examination, imaging plays a critical role in staging and determination of deep margins for either tumor resectability or radiation planning. This article discusses the relevant anatomy on magnetic resonance imaging (MRI), including the lips and gingiva, floor of mouth, and oral tongue. This is followed by a discussion of standard MRI techniques, American Joint Committee on Cancer (AJCC) classification, and relevant MRI findings with discussion and imaging examples of carcinoma in major sites, including floor of mouth, oral tongue, buccal mucosa, bony upper alveolus, hard palate, and retromolar trigone. A brief summary of newer imaging techniques for evaluation of oral cancer is also presented.     

鼻咽癌侵犯相邻结构的MRI与CT的对比分析

目的对鼻咽癌侵犯周围结构进行MRI与CT比较分析，评价MRI相对于CT对1992福州分期产生的影响。方法收集经病理证实初诊鼻咽癌42例，在CT和MRI上分别评价各个解剖部位的受侵情况；并按照RTOG推荐的分区标准，将颈部分为Ⅰ-Ⅵ个区进行评判；按照1992福州分期，作CT与MRI的对比。结果MRI对于口咽、颅底骨质、海绵窦、鼻窦、颞下窝等侵犯的检出率明显高于CT；MRI使47．6％的T期发生了改变，23．8％的N分期发生了改变，26．2％的临床分期发生改变。结论MRI在显示鼻咽癌对周围结构的侵犯方面有着巨大的优势，它能为临床准确地勾画出放疗靶区，指导合理的治疗。为了让MRI在鼻咽癌诊断和治疗中发挥更大的作用，有必要尽早出台MRI的临床分期标准。     

常见CPA区占位性病变的影像学特征分析

目的:总结分析40例常见桥小脑角区占位性病变的CT及MRI表现与特征,提高对桥小脑角区占位性病变的认识。材料与方法:对我院40例经临床或手术病理证实的桥小脑角区占位性病变的回顾性分析,15例行CT检查,40例均行MRI平扫及增强检查。结果:40例中听神经瘤28例,脑膜瘤8例,表皮样囊肿4例。均有各自特征性的CT和MRI表现,本组CT定位、定性准确率为70%、60%,MRI为100%、99%。结论:MRI是检查桥小脑角区占位性病变的首选方法,对桥小脑角区占位性病变诊断及鉴别诊断有重要价值。     

Motion artifact in magnetic resonance imaging: implications for automated analysis

Automated measures of cerebral magnetic resonance images (MRI) often provide greater speed and reliability compared to manual techniques but can be particularly sensitive to motion artifact. This study employed an automatic MRI analysis program that quantified regional gray matter volume and created images for verification and quality control. Motion artifact was assessed on each image and assigned a rating of none, mild, moderate, or severe. Greater motion artifact was associated with smaller gray matter volumes. Severity of motion artifact is an important, but often overlooked, consideration in the interpretation of automated MRI measures.     

左旋咪唑所致脱髓鞘脑病的CT、MRI评价(附35例报告)

目的 研究左旋咪唑致脱髓鞘脑病的CT、MRI表现特点,探讨CT、MRI的诊断价值。方法 分析35例左旋咪唑致脱髓鞘脑病的CT、MRI及临床资料。结果 本病在CT、MRI上显示为双侧脑室周围及额、顶、枕、颞叶白质区有多发病灶,CT为低密度影,MRI为长T1长T2信号,很少有占位效应。MRI的影像学诊断率明显高于CT。本病的主要临床表现为急性或亚急性起病的弥漫性脑损害的症状和体征。结论 CT、MRI能为左旋咪唑所致脱髓鞘脑病的临床诊断提供重要信息,且MRI优于CT。与有相似影像表现病变的鉴别应紧密结合临床资料,仅凭CT、MRI表现有一定局限性。     

基于一种改进的相位校正算法消除MRI运动伪影

背景：近年来,MRI由于具有高的空间分辨率和软组织对比度,在临床上的运用越来越广泛。但是其成像时间较长,所以容易受到患者身体运动的影响,产生运动伪影。目的：去除MRI图像成像时产生的伪影,改善图像质量。方法：使用改进的相位矫正算法,并结合水平集算法去除图像伪影。去除伪影后使用模糊增强改善处理后图像的质量。结果与结论：实验证明使用改进的相位矫正算法得到的图像比使用原始的相位矫正算法得到的图像效果更加理想。     

股骨头缺血性坏死的CT与MRI对照分析

目的对比股骨头缺血坏死的CT和MRI征象并探讨其相应的病理基础。方法分析和总结18例30髋随访和病理证实的股骨头坏死的CT和MRI影像学资料。结果28髋CT上的粗细不均、凹凸不平、边界较模糊的高密度硬化线均与MRI相应部位的“线样征”对应，另2髋MRI上出现“线样征”而CT仅表现斑点状硬化。CT上高密度硬化线围绕的病变区表现正常者26髋，分别对应MRI“线样征”包绕区脂肪样信号者12髋和混杂信号者14髋；4髋骨小梁模糊与MRI“线样征”包绕区混杂信号者对应。结论CT上高密度硬化线与MRI上“线样征”相对应，是坏死区和正常存活区的反应界面，均可作为诊断股骨头缺血坏死的特异性征象，但MRI较CT能够准确反映不同修复时期的病理变化过程。     

小脑出血的CT、MRI诊断与临床

目的 回顾性分析小脑出血的CT、MRI表现及其诊断价值。方法 观察34例小脑出血患者头颅CT、MRI表现,其中31例行CT,21例行MRI扫描。结果 急性期CT表现为小脑半球或小脑蚓部高密度或次高密度团块状病灶。MRI在急性期、亚急性期和慢性期表现出特征性的信号改变。结论 CT能较早发现出血病灶,但有其局限性,MRI能很好地弥补它的缺陷。若使两者相辅相成,结合临床,可进一步提高小脑出血的临床诊断正确率。     

肾上腺肿瘤的CT、MRI诊断

目的探讨和比较CT、MRI对肾上腺肿瘤的诊断及鉴别诊断价值.方法回顾性分析204例经手术病理及临床证实的肾上腺肿瘤的CT、MRI表现.结果 CT、MRI对肾上腺肿瘤定位、定性(区分良、恶性肿瘤)及判断肿瘤组织学类型的准确性分别为94.02%、91.85%、89.13%和98.15%、95.15%、90.74%.CT像素矩阵图上,25例(75.76%)肾上腺腺瘤内有轻度负CT值区域,非腺瘤无此征象.13例腺瘤在MRI反相位(OP)图像上的信号强度(SI)都有明显下降,SI指数平均(52.65±18.01)%;非腺瘤的信号强度无明显下降.结论结合临床表现和生化检查,CT、MRI能诊断大部分肾上腺肿瘤,两者的诊断价值相似,MRI对较大肿瘤的定位、定性及判断肿瘤组织学类型有优越性.     

Nitinol in Magnetic Resonance Imaging

Surgical and interventional instruments as well as implants can cause significant magnetic resonance image (MRI) artifacts. The artifacts can be used to visualize instruments, cannulae, guide wires, catheters during interventional MRI and Nitinol devices have proven to be useful for MRI procedures. Diagnostic imaging is often compromised in the area of an implant. Complete vanishing of signals occurs in close proximity or inside implants. The paper presents a fundamental evaluation of MRI artifact of Nitinol devices such as Stents, Vena Cava Filter, heart defect closure devices, cannulae, guide wire, localizer, anastomosis device, etc. in a 1.0 Tesla magnetic field. The American Society for Testing Materials (ASTM) recommendations for selection of sequences and test setup were used but the results of this paper are not sufficient for FDA approval.     

Isolated noncompaction of the ventricular myocardium: ultrafast computed tomography and magnetic resonance imaging

This study was undertaken to evaluate the feasibility of ultrafast computed tomography (CT) and magnetic resonance imaging (MRI) for anatomical and pathophysiological diagnosis of isolated noncompaction of the left ventricular myocardium (INVM) compared with other imaging modalities including thallium myocardial imaging. Six patients, three sets of siblings, ranging in age from 13 to 18 years, were included in this study. Two-dimensional echocardiograms revealed numerous prominent trabeculations and deep intertrabecular recesses in one or more ventricular wall segments in all cases. Thallium-201 myocardial imaging disclosed a hypoperfusion area corresponding to the zones where noncompacted ventricular myocardium was localized. Ultrafast CT showed early defects of varying degrees and rate enhancement of the noncompacted ventricular myocardium, implying fibrosis in this area. MRI disclosed inner zones of noncompacted myocardium distinguishable from thin outer zones of compacted myocardium. T2-weighted imaging revealed high intensity areas at the apex of the left ventricle, suggesting disturbed microcirculation due to fibrosis, thrombus formation, and hypokinesis. Cine MRI revealed hypokinesis of the noncompacted ventricular wall during the cardiac cycle. In conclusion, ultrafast CT and MRI provide high-resolution imaging of noncompacted myocardium, and also pathophysiological details regarding this rare disease.