DWI和ADC值测量在脑脓肿和囊变坏死性脑肿瘤鉴别诊断中的价值

目的：评价DWI与ADC值对脑脓肿和囊变坏死性脑肿瘤的鉴别诊断价值以及相关的生物物理学机制。方法：经手术病理证实的脑脓肿25例、囊变坏死性脑肿瘤55例,在术前均接受了常规MRI和DWI检查。结果：脑脓肿在DWI上表现为明显的高信号,ADC值为（0.67±0.178）×10^-3mm^2/s;脑肿瘤囊变坏死灶在DWI上表现为明显的低信号,ADC值为（2.48±0.156）×10^-3mm^2/s,脑脓肿ADC值明显低于脑肿瘤囊变坏死灶ADC值（P〈0.001）。结论：DWI和ADC值测量可有效鉴别脑脓肿与囊变坏死性脑肿瘤。     

磁共振DWI和ADC值在包膜期脑脓肿与坏死囊变性脑肿瘤鉴别诊断中的应用

目的探讨磁共振扩散加权成像(DWI)及表观扩散系数(ADC)值在包膜期脑脓肿与坏死囊变脑肿瘤鉴别中的临床应用价值。方法经手术病理证实的包膜期脑脓肿15例和坏死囊变脑肿瘤20例患者均经常规MRI扫描和DWI扫描,对比分析包膜期脑脓肿及坏死囊变脑肿瘤的DWI和ADC图表现,并测量脑脓肿脓腔及脑肿瘤坏死囊变区内的平均ADC值,进行统计学分析。结果包膜期脑脓肿脓腔在DWI上表现为高信号,ADC图呈低信号;脑肿瘤坏死囊变区在DWI上表现为低信号,ADC图呈高信号。所有脑脓肿的平均ADC值为(0.69±0.18)×10-3mm2/s,坏死囊变脑肿瘤的平均ADC值为(2.43±0.16)×10-3mm2/s,两者比较有显著性差异(P<0.01)。结论 DWI与ADC值测量能准确反映包膜期脑脓肿与坏死囊变脑肿瘤的不同液态性质,对其鉴别诊断有重要价值。     

颅内表皮样囊肿和蛛网膜囊肿的DWI鉴别诊断

目的:探讨磁共振扩散加权成像(DWI)对颅内表皮样囊肿和蛛网膜囊肿的鉴别诊断价值。方法:对20例颅内表皮样囊肿和15例颅内蛛网膜囊肿患者进行常规MRI及DWI检查,并获得表观扩散系数(ADC)图,分别测量病变区、健侧脑组织及健侧侧脑室内脑脊液的ADC值并进行统计学分析。结果:表皮样囊肿和蛛网膜囊肿在T1WI和T2WI上呈相同的信号改变;在DWI上表皮样囊肿呈高信号,而蛛网膜囊肿呈低信号;表皮样囊肿的ADC值[(10.197±0.329)×10-4mm2/s]明显低于蛛网膜囊肿[(30.098±1.510)×10-4mm2/s],差异有显著性意义(P<0.05)。结论:DWI对于表皮样囊肿与蛛网膜囊肿的鉴别诊断具有重要价值。     

MR扩散加权成像鉴别颅内囊性病变的价值

目的探讨MR扩散加权成像（DWI）在颅内囊性病变中的鉴别诊断价值。方法对76例经临床及手术病理证实的颅内囊性病变患者，行常规MR、DWI及增强MR检查，其中脑脓肿19例，原发性脑胶质瘤20例，小脑血管母细胞瘤4例，脑转移瘤10例，蛛网膜囊肿7例，表皮样囊肿16例。回顾性分析颅内囊性病变的DWI信号特征，定量测定囊性变区表观扩散系数（ADC）值。结果DWI上19例脑脓肿呈高信号；34例脑肿瘤患者中，除3例脑胶质瘤呈高信号、1例呈等信号，1例脑转移瘤呈高信号外，其余29例均呈低信号。各种病变ADC值分别为：脑脓肿（0．62±0．15）×10^-3 mm^2／s、脑胶质瘤（2．39±0．78）×10^-3 mm^2／s、脑血管母细胞瘤（2．68±0．40）×10^-3 mm^2／s、脑转移瘤（2．79±0．79）×10^-3 mm^2／s。脑脓肿与脑胶质瘤、脑血管母细胞瘤、脑转移瘤的囊变坏死区ADC值比较，差异均有统计学意义（P〈0．01）；脑胶质瘤与脑血管母细胞瘤、脑转移瘤的囊变坏死区ADC值比较，差异均无统计学意义（P〉0．05）。7例颅内蛛网膜囊肿的DWI呈低信号；16例表皮样囊肿DWI呈明显高信号。颅内蛛网膜囊肿和表皮样囊肿的ADC值分别为（2．96±0．36）×10^-3 mm^2／s和（0．94±0．13）×10^-3 mm^2／s，二者之间差异有统计学意义（P〈0．01）。结论DWI及ADC值对鉴别脑脓肿和囊性或坏死性脑肿瘤具有重要的价值，DWI表现为低信号的颅内囊性病变可除外脑脓肿。     

磁共振扩散加权成像诊断脑脓肿的价值

目的: 评价磁共振扩散加权成像对脑脓肿的诊断及与颅内囊性、坏死性肿瘤鉴别诊断的价值.材料和方法: 对14例脑脓肿与17例颅内囊性、坏死性肿瘤的DWI信号特征进行分析,测量并比较病灶的表观扩散系数 (ADC) 值、病灶与对照区的ADC值比率(ADC率,rADC).结果: 14例脑脓肿在DWI上均呈程度不等的高信号,其中12例在ADC上呈低信号,平均ADC值为(0.62±0.29)×10-3mm2/ s,平均rADC为0.77±0.36;17例囊性、坏死性肿瘤中15例在DWI上呈低信号,16例在ADC上呈高信号,平均ADC值为(2.37±0.70)×10-3mm2/ s,平均rADC为3.24±1.08.统计分析显示脑脓肿与囊性坏死性肿瘤的平均ADC值及rADC的差异均有显著性意义(P<0.01),前者均显著低于后者; DWI与ADC相结合对脑脓肿的诊断敏感度和特异度分别为84.6%、94.1%,显著高于文献报道相应常规MRI的60%、27.27%.结论: DWI与ADC能有效反映脓肿与囊性、坏死性肿瘤的不同液态性质,对脑脓肿的诊断与鉴别诊断具有重要价值.     

DWI结合T2WI在包膜期脑脓肿与囊性转移瘤鉴别诊断中的价值

目的 探讨磁共振扩散加权成像(DWI)结合T2WI在包膜期脑脓肿和囊性脑转移瘤鉴别诊断中的价值.方法 回顾性分析经病理或临床随访证实的23例包膜期脑脓肿和24例脑囊性转移瘤患者的MRI常规平扫、增强及DWI检查资料,b值取0、500 s/mm2、1000 s/mm2,根据信噪比(SNR)及图像质量指数(QI)取最佳b值的DWI,分别测量病灶囊变区、囊壁、对侧正常脑组织平均ADC值并计算3项rADC值,两组间采用两独立样本t检验进行统计学分析.结果 包膜期脑脓肿T2WI低信号暗带及靶环征是鉴别囊性转移瘤的MRI特征性表现.取b值1000s/mm2时,脑囊性转移瘤囊变坏死区DWI呈低信号22例,高信号1例,囊变坏死区、囊壁、对侧正常脑组织平均ADC值分别为(0.64±0.14)×10-3mm2/s、(1.56 ±0.17)×10-3mm2/s、(0.79±0.18)×10-3mm2/s,脑囊性转移瘤囊壁rADC值、病灶rADC值、囊液rADC值分别为1.19±0.37、0.48 ±0.25、2.74±0.75.包膜期脑脓肿囊液DWI呈高信号,包膜期脑脓肿囊变区、囊壁、对侧正常脑组织平均ADC值分别为(2.10±0.28)×10-3mm2/s、(1.51±0.09)×10-3mm2/s、(0.81±0.15)×10-3mm2/s,包膜期脑脓肿囊壁rADC值、病灶rADC值、囊液rADC值分别为1.37±0.48、1.49±0.62、0.95±0.50.包膜期脑脓肿与脑囊性转移瘤囊液ADC值、病灶rADC值、囊液rADC值差异均有显著统计学意义(P＜0.01),囊壁ADC值、囊壁rADC值差异均无统计学意义(P＞0.05).结论 包膜期脑脓肿壁上T2WI特征性的低信号暗带及靶环征有别于囊性转移瘤,b值=1000 s/mm2时囊液DWI、囊液ADC值、病灶rADC值、囊液rADC值能有效反映包膜期脑脓肿与囊性脑转移瘤的不同囊液性质,DWI结合T2WI对包膜期脑脓肿与囊性脑转移瘤的鉴别诊断具有重要价值.     

脑实质表皮样囊肿的磁共振成像表现及鉴别诊断

目的探讨脑实质表皮样囊肿的磁共振成像(MRI)特点及鉴别诊断。方法回顾性分析8例脑实质表皮样囊肿及12例脑脓肿的MRI表现,包括常规序列、DWI序列及增强扫描,并比较表皮样囊肿、脓肿及正常脑脊液的ADC值。结果①脑实质表皮样囊肿常规表现为均匀长T1、T2信号或混杂T1、T2信号,FLAIR信号不均匀降低,DWI为均匀或不均匀高信号,ADC图呈混杂信号,增强扫描7例无强化、1例边缘强化,所有病灶均无瘤周水肿;②3者ADC值差异有统计学意义,脑脓肿最低为(0.76±0.12)×10^-3mm²/s,脑脊液最高为(2.98±0.16)×10^-3mm²/s,表皮样囊肿为(1.18±0.09)×10^-3mm²/s。结论常规MRI序列结合DWI序列可以准确的诊断脑实质表皮样囊肿。     

扩散加权成像在鉴别颅内环形强化病灶的价值

目的讨论扩散加权成像(DWI)和表观扩散系数(ADC)在鉴别颅内环形强化病灶性质的价值。资料与方法应用1.5TMR对16例胶质瘤、6例转移瘤、4例脑脓肿进行常规MR及DWI成像和ADC测量,分析其影像学表现。结果4例脑脓肿在DWI上呈高信号,16例胶质瘤和6例转移瘤呈低信号,脓肿腔平均ADC值为0.44×10-3cm2/s,脑肿瘤坏死囊变区平均ADC值为1.82×10-3cm2/s(P<0.01)。结论DWI和ADC值可以用来鉴别脑脓肿及坏死囊变的肿瘤病灶。     

扩散加权成像鉴别诊断囊性星形细胞瘤与包膜期脑脓肿的价值

目的 评价扩散加权成像(DWI)和表观扩散系数(ADC)值鉴别诊断囊性星形细胞瘤(CA)与包膜期脑脓肿(BACP)的价值.方法 回顾性分析经手术病理或临床随访证实的16例CA和12例 BACP,治疗前均接受常规MRI及DWI检查,分别测量CA与BACP囊变区及对侧相应脑组织(CCBT)的平均ADC值.结果 DWI上16例CA均呈低信号,10例BACP呈高信号(2例低信号).CA、BACP和两者的CCBT的平均ADC值为 (1.42±0.16)×10-3mm2/s、(0.61±0.20)×10-3 mm2/s、(0.89±0.08)×10-3mm2/s、(0.90±0.08)×10-3 mm2/s,CA、BACP囊变区之间以及与CCBT的ADC值间显著差异(P<0.01).结论 DWI和ADC值鉴别诊断CA与BACP时具有重要价值.     

扩散张量成像对脑脓肿与坏死囊变性胶质瘤的鉴别诊断价值

目的 探讨磁共振扩散张量成像(DTI)对脑脓肿与坏死囊变性胶质瘤的鉴别诊断价值.资料与方法 回顾性分析2例经手术病理、3例经临床复查证实的脑脓肿和10例经手术病理证实的坏死囊变性胶质瘤.所有病例均行常规MR平扫、增强及DTI检查.构建表观扩散系数(ADC)图和各向异性分数(FA)图.测量病灶的坏死囊变区及其周围水肿区的ADC和FA值,计算其平均值,并行组间统计学分析.结果 脑脓肿脓腔扩散加权图像(DWI)表现为高信号者4例,低信号1例;胶质瘤坏死囊变区DWI表现为高信号者1例,混杂信号1例,低信号8例.脓腔、胶质瘤坏死囊变区ADC平均值分别为(0.79±0.11)×10-3 mm2/s、(2.38±0.28)×10-3 mm2/s,二者之间ADC值差异有统计学意义(t=6.45,P＜0.01).胶质瘤与脑脓肿周围水肿区ADC值分别为(1.65±0.13)×10-3 mm2/s、(1.94±0.17)×10-3 mm2/s,二者之间差异有统计学意义(t=1.98,P＜0.05).在FA图上,脓腔、胶质瘤坏死囊变区均表现为低信号,FA值分别为0.17±0.06、0.11±0.03,二者差异有统计学意义(t=2.42,P＜0.05),二者周围水肿区FA值分别为0.21±0.04、0.19±0.08,二者之间差异无统计学意义(t=1.13,P＞0.05).结论 DTI通过构建DWI图、ADC图和FA图能有效反映脓肿与坏死囊变性胶质瘤的不同液态性质.绝大多数脑脓肿的脓腔在DWI图上表现为高信号,ADC图上为低信号,而胶质瘤坏死囊变区则与之相反;脑脓肿周围水肿ADC值高于胶质瘤瘤周水肿.DTI对脑脓肿与坏死囊变性胶质瘤的鉴别诊断具有重要价值.     

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。     

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.     

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.     

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.     

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.     

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).     

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.     

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.     

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.