MRSWI在脑微出血及脑血管畸形中的应用研究

目的：探讨 MR 磁敏感加权成像(SWI)在不同脑疾病伴微出血(CMBs)及脑血管畸形中的应用及价值。方法回顾性分析76例不同脑疾病伴 CMBs 及25例脑血管畸形的 MRI 资料：(1)将不同脑疾病患者的常规 T1 WI、T2 WI、T2 FLAIR、DWI 显示的 CMBs 数目、敏感性与 SWI 序列比较。(2)评价 SWI 图、最小信号强度投影(MIP)、相位图(Phase)对 CMBs 显示的差异：大小、数目、信号及边界特点。(3)评价 SWI 在不同脑血管畸形诊断中的价值。结果(1)SWI 序列检出 CMBs 1524个,T1 WI、T2 WI、T2 FLAIR、DWI 分别检出 CMBs 294个、87个、361个、391个,对 CMBs 病灶检出敏感性分别为19.3%、5.7%、23.7%、25.7%,多序列 CMBs检出数目及敏感性比较,差异均有统计学意义(P 均<0.05)。(2)SWI、MIP 图分别检出 CMBs 1524个、1539个,两者图像上CMBs 均表现为≤10 mm 类圆形或点状低信号或以低信号为主的混杂信号;Phase 图检出 CMBs 1521个,表现为高信号或以高信号为主的混杂信号;对于 CMBs 大小、数目、边界的显示,MIP 与 SWI 相似,Phase 不及前两者。(3)静脉发育畸形12例,SWI 均可清晰显示“海蛇头”,即多条低信号髓静脉呈辐射状汇入粗大的引流静脉;毛细血管扩张症6例,SWI 均表现为多发小圆形均匀低信号或“靶征”,MIP 特异性表现为连续层面病灶与小静脉相连;动静脉畸形2例,1例 SWI 仅显示迂曲小血管及粗大引流静脉;另1例 SWI 清晰显示了瘤巢及粗大引流静脉呈高信号汇入乙状窦;海绵状血管瘤4例,SWI 均呈“桑葚状”,病灶中心呈不均匀斑点状高低混杂信号,周边伴低信号环。Sturge-Weber 综合征1例,MIP 图可见与 CT 一致脑回样钙化所致的低信号影,大脑半球及小脑幕附近显示大量迂曲增宽、粗细不均静脉血管。结论SWI 可作为 CMBs 检出的重要序列。不同的脑血管畸形在 SWI 序列有特异性表现,结合 MRI 平扫有助于作出准确诊断。     

磁敏感加权成像在脑血管畸形疾病中的应用

目的 评价磁敏感加权成像在诊断脑血管畸形性疾病中的应用价值.方法 58例脑血管畸形(海绵状血管瘤、动静脉血管畸形及静脉血管畸形)患者行1.5T MRI检查,包括SE序列,SWI序列,部分还包括MRI增强、DWI、T2*WI、MRA和MRV.SWI所得到图像资料经过工作站进行后处理,获得SWI磁化率加权图、SWI MinIP图和SWI相位图.将所有资料进行对比分析,比较SWI相对于常规序列在脑血管畸形疾病中的诊断价值.结果 30例海绵状血管瘤患者SWI的磁化率加权图像特点表现为完全低信号6个,另24个表现为低信号中伴点状、斑状等或高信号,周围环绕较宽低信号,出现明显的"铁环征".病变范围的显示较常规序列范围大.在14例动静脉血管畸形中,SWI较常规序列多发现7例动静脉血管畸形(AVM),有10例同时显示供血动脉及引流静脉.在14例静脉血管畸形中,SWI较常规序列多发现病变8处,并能同时显示更多细小髓静脉及引流静脉.结论 SWI能够较常规扫描序列更好的对脑血管畸形,尤其是不典型的海绵状血管瘤做出诊断.     

3D-TOF MRA及SWI对脑血管畸形的对照研究

目的:通过分析脑动静脉畸形和海绵状血管瘤的的3D-TOF MRA及SWI磁共振表现,探讨3D-TOF MRA及SWI对脑血管畸形的诊断价值。方法:对我院收治的44例血管畸形进行高场磁共振成像,并加扫3D-TOF MRA及SWI序列,其中26例海绵状血管瘤、18例动静脉畸形。通过分析SW I和3D-TOF-MRA技术对脑血管畸形的显示情况,比较二者对脑血管畸形的检出率以及细微特征的鉴别能力等。结果:3D-TOF MRA可以清晰显示动静脉畸形的部位、大小、输入动脉的来源、输出静脉的去向等;海绵状血管瘤MRA检查均未见异常供血动脉,病灶内无异常流空信号。SWI可清晰显示海绵状血管瘤,病灶的数目及范围较常规序列增大;SWI只能显示动静脉畸形迂曲的小静脉,但不能直观显示畸形血管团的全貌及输入动脉等粗大血管的情况。结论:3D-TOF MRA技术对于AVM之类高流速低阻力的血管畸形的显示具有独特的价值,而SWI技术则对于海绵状血管瘤等小血管或低流速的血管畸形的显示具有明显的优势。     

磁共振磁敏感加权成像在脑血管性疾病中的应用价值

目的探讨磁敏感加权成像(SWI)在常见脑血管性疾病中的应用价值。资料与方法回顾性分析经临床随访及数字减影血管造影(DSA)证实的26例脑血管疾病患者的MRI资料,与常规T1WI、T2WI、T2-FLAIR序列进行比较,分析各种脑血管性疾病在SWI上的影像学表现,评价SWI在诊断脑血管性疾病中的优势。结果海绵状血管瘤8例,常规MRI检出病灶11处,SWI共发现病灶37处,病灶在SWI图上以低信号为主,部分病灶内可见点状高信号;动静脉畸形2例,SWI对动静脉畸形的血管团及引流静脉能够清晰显示,但对其供血动脉显示欠佳;静脉畸形3例,常规MRI仅显示较粗大的流空血管,SWI清晰显示周围小畸形血管。脑梗死10例,SWI显示2例急性期脑梗死灶内的微小出血灶,常规MRI无异常发现。脑血管淀粉样变性3例,SWI对其引起的微小出血灶及血肿能清晰显示。结论 SWI能够清晰显示低血流量畸形血管及微小出血灶,为MRI诊断脑血管疾病提供更加详细、准确的信息。     

超高场3.0T磁共振磁敏感加权成像诊断隐匿性脑血管畸形的临床应用

目的 探讨磁敏感加权成像( SWI)诊断隐匿性脑血管畸形(angiographically occult cerebrovascular malformation,AOVM)的应用价值.资料与方法 回顾性分析119例AOVM(海绵状血管瘤42例,毛细血管扩张症46例,发育性静脉畸形31例)患者的MRI表现,比较SWI与其他常规MRI序列显示AOVM的敏感性和特异性.结果 119例中,以SWI发现病灶数目最多,并且其影像表现具有特征性,与其他常规MRI序列相比,病灶检出的差异有统计学意义(P＜0.05).结论 SWI显示AOVM较其他常规MRI序列有更高的敏感性和特异性,是诊断AOVM的最佳序列,应作为AOVM的常规检查序列.     

脑实质内海绵状血管瘤的影像学诊断

目的：探讨脑实质内海绵状血管瘤(CA)的CT、MRI、MRA认和DSA表现并比较四种影像学检查方法的诊断价值。方法：回顾性分析20例CA的影像学表现，其中15例经手术病理证实，5例经影像学及临床随访证实。20例进行CT和MRI平扫、MRA认，13例行CT增强扫描，15例行MRI增强扫描，12例行DSA检查。结果：CA可发生于脑内任何部位．以单发多见(17／20，占85％)。20例CA检出25个病灶。CT和MRI平扫均发现所有病灶。CA的CT平扫均表现为高密度或稍高密度；13例CT增强扫描发现15个病灶，其中10个病灶无强化，5个病灶轻度强化。CA的MRI平扫表现为T1WI呈等或低信号12个，高信号8个，混杂信号5个；T2WI全部病灶均表现为高低混杂信号，23个病灶周围伴有低信号环，2个病灶周围有水肿带，无占位效应；15例MRI增强扫描发现17个病灶，其中7个病灶出现瘤体血管床轻中度强化，2个病灶边缘强化，8个病灶无强化。20例CA行3D TOF MRA认均未见异常血管影。12例行全脑DSA检查未见供血动脉与引流静脉。4例表现为毛细血管期或静脉窦期富血管性病变。结论：CA具有较典型的影像学表现．CT和MRI平扫对明确诊断具有重要意义，且MRI优于CT；CA的CT和MRI增强扫描无特征性表现；MRA和DSA对诊断CA价值有限。     

颅内海绵状血管瘤的CT和MRI诊断

目的 探讨CT和MRI对颅内海绵状血管瘤的表现和诊断价值。资料与方法 经手术病理证实的颅内海绵状血管瘤22例,其中脑内型海绵状血管瘤21例,脑外型海绵状血管瘤1例。10例行CT检查,16例行MRI检查,13例行MRA检查。结果 脑内型海绵状血管瘤可位于脑内任何部位,单发病灶多见,周围无或轻度水肿,无明显占位效应。CT平扫为稍高密度影,钙化占72．7％,增强扫描大都无强化;MR T1WI表现为桑葚状混杂高信号．周围有云絮状低信号环,增强后病灶大都无强化;MRA检查未见异常血管。脑外型病灶位于中颅窝、鞍旁,MRI呈类似哑铃形较均匀的稍长T1、长T2信号,增强扫描见明显均匀强化．MRA检查未见异常血管。结论 脑内型海绵状血管瘤的MRI表现较有特异性,结合CT和MRA可明确诊断;脑外型者易误诊,对CT和MRI表现类似的中颅窝脑膜瘤,应考虑到本病的可能。     

脑静脉性血管瘤的MRI及磁敏感加权成像表现

目的 评价磁敏感加权成像(susceptibility weighted imaging,SWI)在脑静脉血管畸形的诊断价值.方法 回顾性分析16例脑静脉性血管瘤(CVH)的MRI表现.16例均行MRI平扫,其中10例行MR增强扫描,10例行SWI检查.结果 16例中,发生于小脑半球6例,顶叶4例、额叶2例、颞枕叶2例、枕叶1例,侧脑室旁1例,伴发海绵状血管瘤1例.16例中,MRI平扫显示病灶13例,表现为管状、小圆状低信号;10例MR增强检查显示所有病灶,表现为"水母头"样强化;10例SWI均能清晰显示病灶,表现为"水母头"样低信号影;结论 MRI结合SWI是诊断CVH的无创和有效手段.     

颅内海绵状血管瘤的CT和磁共振成像影像诊断

目的探讨脑内海绵状血管瘤的cT、磁共振成像（MRI）影像表现。方法经随访及手术病理证实的脑内海绵状血管瘤13例,4例cT常规检查后行MRI扫描,9例仅行MRI检查。13例患者中2例行磁共振血管造影（MRA）检查,8例行MRI增强检查。结果脑内海绵状血管瘤可位于脑内任何部位,单发病灶多见,瘤周多无水肿及占位效应。cT平扫为稍高密度,有时可有斑片状钙化。MRI中病灶信号混杂,周边有环状低信号。增强后2例病灶轻度强化,6例无明显强化。MRA均未见异常血管团。结论脑内型海绵状血管瘤的MRI表现右明显特秆忡结会CT和MRA可明确诊睐斤     

磁敏感加权成像在颅内海绵状血管瘤诊断中的应用价值

目的 探讨磁敏感加权成像(SWI)技术在颅内海绵状血管瘤诊断中的应用价值.方法 对29例CT或MR常规检查疑有海绵状血管瘤的患者进行磁敏感加权成像序列扫描.结果 29例病例中单发者为21例,多发者为8例.其中13例为手术病理证实,其余经多位临床及影像副主任医师分别诊断为海绵状血管瘤.常规扫描发现病灶82个,其中表现为典型血管瘤征象("铁环征")为30个.磁敏感序列发现144个,其中均匀性低信号病灶117个,低信号中含有混杂信号病灶27个.结论 磁敏感加权成像对于颅内海绵状血管瘤特别是在常规MR扫描无阳性表现或不典型者具有很高的应用价值.     

DSA功能性参数的提取与利用

本文介绍了在临床实际中利用功能性参数，对冠状动脉ＤＳＡ心肌血流灌注成像、冠状动脉血流量测定、左心室功能测定、肺动脉高压程度的评价等项目研究结果。重点讨论了提取ＤＳＡ功能性参数的一般方法，认为功能性参数在现代影像诊断学中的作用是对疾病做出程度、定量、动态及功能诊断。     

Fast imaging of phosphocreatine in the normal human myocardium using a three-dimensional RARE pulse sequence at 4 Tesla

PURPOSE: To investigate the use of a three-dimensional rapid acquisition with relaxation enhancement (RARE) pulse sequence for direct acquisition of phosphocreatine (PCr) images of the human myocardium. MATERIALS AND METHODS: A short elliptical birdcage radiofrequency (RF) body coil was constructed to produce a uniform flip angle throughout the chest cavity. In vivo images using a spectrally-selective RARE sequence with a spatial resolution of 1.2 cm x 1.2 cm x 2.5 cm (4 cm(3)) were acquired in nine minutes and 40 seconds. RESULTS: Scans of phantoms demonstrated excellent spectral selectivity. The signal-to-noise ratio in the myocardium ranged from 12.6 in the anterior wall to 5.3 in the mid septum. CONCLUSION: This study demonstrates that PCr data can be acquired using a three-dimensional RARE sequence with greater spatial and temporal resolution than spectroscopic techniques.     

Current Status of Optical Imaging for Evaluating Lymph Nodes and Lymphatic System

Optical imaging techniques use visual and near infrared rays. Despite their considerably poor penetration depth, they are widely used due to their safe and intuitive properties and potential for intraoperative usage. Optical imaging techniques have been actively investigated for clinical imaging of lymph nodes and lymphatic system. This article summarizes a variety of optical tracers and techniques used for lymph node and lymphatic imaging, and reviews their clinical applications. Emerging new optical imaging techniques and their potential are also described.     

Molecular imaging of the lungs

An emerging suite of new imaging techniques offer the ability to monitor and quantify molecular and cellular processes in the lungs noninvasively. These techniques take advantage of dramatic advances in both imaging technology as well as molecular and cell biology. Molecular imaging is being used with increasing regularity in research protocols, and forms of molecular imaging have found their way into the patient care setting (eg, positron emission tomography imaging in cancer). Such techniques will afford the basic scientist as well as the clinician an unprecedented opportunity for in vivo study of the lung biology that drives normal pulmonary physiology as well as pathophysiology.     

Dynamic bioluminescence imaging for quantitative tumour burden assessment using IV or IP administration of <Emphasis Type="SmallCaps">d</Emphasis>-luciferin: effect on intensity,time kinetics and repeatability of photon emission

Introduction In vivo bioluminescence imaging (BLI) is a promising technique for non-invasive tumour imaging. d-luciferin can be administrated intraperitonealy or intravenously. This will influence its availability and, therefore, the bioluminescent signal. The aim of this study is to compare the repeatability of BLI measurement after IV versus IP administration of d-luciferin and assess the correlation between photon emission and histological cell count both in vitro and in vivo. Materials and methods Fluc-positive R1M cells were subcutaneously inoculated in nu/nu mice. Dynamic BLI was performed after IV or IP administration of d-luciferin. Maximal photon emission (PE_max) was calculated. For repeatability assessment, every acquisition was repeated after 4 h and analysed using Bland–Altman method. A second group of animals was serially imaged, alternating IV and IP administration up to 21 days. When mice were killed, PE_max after IV administration was correlated with histological cell number. Results The coefficients of repeatability were 80.2% (IV) versus 95.0% (IP). Time-to-peak is shorter, and its variance lower for IV (p < 0.0001). PE_max was 5.6 times higher for IV. A trend was observed towards lower photon emission per cell in larger tumours. Conclusion IV administration offers better repeatability and better sensitivity when compared to IP. In larger tumours, multiple factors may contribute to underestimation of tumour burden. It might, therefore, be beneficial to test novel therapeutics on small tumours to enable an accurate evaluation of tumour burden. Marleen Keyaerts is a Ph. D. fellow of the Research Foundation—Flanders (Belgium; FWO).     

Molecular imaging programs in the United States: results of a national survey

RATIONALE AND OBJECTIVES: We sought to identify and describe the characteristics of molecular imaging (MI) programs in the United States and to determine the factors considered critical for their future. MATERIALS AND METHODS: In a cross-sectional study, a validated survey was sent to members of the Society of Chairmen in Academic Radiology Departments (SCARD) in the United States, and 26 variables were studied. RESULTS: The response rate was 40.3%; 67.9% of the departments surveyed have an MI program. The main focus of 47.4% of departments is oncology. The number of radiologists working for the department was the only variable found to be significantly positively correlated with (1) number of researchers in the MI program, (2) number of MI modalities available, (3) total number of grants, and (4) having ongoing MI clinical trials. These four variables plus the number of federal grants and the space used by MI programs were independent of the geographical region, hospital size (number of beds), and department size (number of radiological examinations per year). All the MI programs received grants during 2005. Only 16.1% have no alliances with industry. Among all the departments, 82% identified staff training and recruitment as the keys for success; 78.57% considered oncology the most important future application of MI and cancer management the hospital service most affected by MI. CONCLUSION: MI programs are starting to be more widespread throughout the United States, and the trend is for more academic radiology departments to become engaged in MI activities; their development is independent of department characteristics. Radiology departments strongly agreed about the key components for success of MI initiatives and the areas that will be most affected by MI applications.     

Phase insensitive preparation of single-shot RARE: Application to diffusion imaging in humans

Although RARE and GRASE can produce single-shot images of excellent quality, their utility has been restricted because preparation of the magnetization with interesting contrast before imaging can cause severe artifacts. These artifacts relate to the strong sensitivity of multiple spin echo sequences to the phase of the prepared magnetization. Modifications of the RARE sequence to eliminate these artifacts are discussed, and an approach that eliminates the artifact producing signals from the very first echo is presented. The approach is applied to diffusion imaging of the human brain in normal volunteers and one patient.     

Head and neck imaging: the role of CT and MRI

High-resolution computed tomography (CT) and magnetic resonance imaging (MRI) have become indispensable tools for the evaluation of conditions involving the head and neck. Complex anatomic structures and regions, such as the orbit, skull base, paranasal sinuses, deep spaces of the neck, larynx, and lymph nodes, require that the radiologist be familiar with the imaging modalities available and their appropriate applications. The purpose of this article is to review the techniques of CT and MRI and the roles they play in clinical practice, including head and neck disorders.     

CAIPIRINHA-Dixon-TWIST (CDT)-volume-interpolated breath-hold examination (VIBE) for dynamic liver imaging: Comparison of gadoterate meglumine,gadobutrol and gadoxetic acid

Purpose

CAIPIRINHA-Dixon-TWIST (CDT)-VIBE is a robust method for abdominal magnetic resonance imaging providing both high spatial and high temporal resolution. The purpose of this study was to examine the influence of different gadolinium based contrast agents (GBCA) on image quality (IQ) with CDT-VIBE.

Materials and methods

In this IRB-approved, retrospective, inter-individual comparison study, 86 patients scanned at 3T were included. Within 28 s, 14 high-resolution 3D datasets were acquired using CDT-VIBE. 37 patients received 0.1 mmol/kg gadoterate meglumine, 28 patients 0.1 mmol/kg gadobutrol, and 19 patients 0.1 mL/kg gadoxetic acid. Two blinded, board-certified radiologists assessed the image quality on a 5 point scale, as well as the number of hepatic arterial dominant (HAD) phases.

Results

Regardless of the GBCA utilized, CDT-VIBE resulted in good IQ in terms of best IQ achieved among all 14 datasets (gadobutrol 4.3, gadoterate meglumine 3.9, gadoxetic acid 3.7). With respect to worst IQ, the three groups showed statistically significant differences with gadobutrol receiving the highest rating (3.6) and gadoxetic acid the lowest (2.4) (gadoterate meglumine 3.0; 0.0014 < p < 0.0485). No statistically significant differences were found in the mean number of acquired HAD phases (gadobutrol 3.4, gadoterate meglumine 3.9, gadoxetic acid 3.1; 0.18 < p < 0.57).

Conclusion

Different gadolinium-based contrast agents can be utilized for dynamic liver imaging with CDT-VIBE resulting in good image quality.     

A Velocity k-Space Analysis of Flow Effects in Echo-Planar and Spiral Imaging

A velocity k-space formalism facilitates the analysis of flow effects for imaging sequences involving time-varying gradients such as echo-planar and spiral. For each sequence, the velocity k-space trajectory can be represented by k_v (k)_r; that is, its velocity-frequency (k_r) position as a function of spatial-frequency (k_r) position. In an echo-planar sequence, k_r is discontinuous and asymmetric. However, in a spiral sequence, k_r is smoothly varying, circularly symmetric, and small near the k_r origin. To compare the effects of these trajectory differences, simulated images were generated by computing the k-space values for an in-plane vessel with parabolic flow. Whereas the resulting echo-planar images demonstrate distortions and ghosting that depend on the vessel orientation, the spiral images exhibit minimal artifacts.