同一个体3.0T与1.5T乳腺MR扩散加权成像的图像质量比较

目的比较3.0 T与1.5 T MR正常乳腺组织扩散加权成像(DWI)的图像质量,从而评价3.0 T乳腺MRDWI的可行性。方法对44名女性乳腺受检者分别在3.0 T MR与1.5 T MR上行DWI。3.0 T DWI应用选择性水激励(Water excitation)技术行脂肪抑制,1.5 T DWI应用频率选择脂肪饱和(Fatsat)技术行脂肪抑制,b值均为0,1000 s/mm2,其他参数相同。比较3.0 T及1.5 T乳腺MR DWI图像的主观质量评分,测量并计算3.0 T及1.5 T乳腺MR DWI乳腺组织信噪比(SNR)及表观扩散系数(ADC)值,进行统计学分析。结果 3.0 T乳腺MR DWI的图像质量平均评分为(3.07±0.79),主观质量评分达到3分(可以诊断)及以上者为34名,占总检查例数的77.27%。1.5 T乳腺MR DWI的图像质量平均评分为(3.23±0.52),主观质量评分达到3分及以上者为42例,占总检查例数的95.45%。两者比较差异无统计学意义(P=0.1615,>0.05)。3.0 T乳腺MR DWI的乳腺组织SNR为(52.28±19.34),1.5 T乳腺MR DWI的乳腺组织SNR为(49.97±17.99)。3.0 T乳腺MR DWI图像乳腺组织平均SNR略高于1.5 T,但二者差异无统计学意义(P=0.5500,>0.05)。3.0 T MR DWI的平均ADC值为(1.80±0.44)×10-3mm2/s,1.5 T MR DWI的平均ADC值为(1.73±0.32)×10-3 mm2/s,两者比较差异无统计学意义(P=0.0652,>0.05)。结论 DWI可用于3.0 T MR乳腺成像,图像质量可以达到1.5 T MR DWI的效果,且ADC值与1.5 T的ADC值无明显差异。     

RESOLVE-DWI技术在脊髓型颈椎病成像中的应用研究

目的探讨高清扩散读出方向上分段扩散成像(readout-segmented diffusion imaging technique,RESOLVE)DWI技术在脊髓型颈椎病MRI成像中应用价值。方法选取我院行MRI检查的脊髓型颈椎病患者100例,均行常规回波平面成像(echo planar imaging,EPI)DWI序列和RESOLVE-DWI序列扫描,对两组DWI序列的图像质量进行主观和客观评价,结果采用SPSS 23.0数据分析软件进行统计学分析。结果EPI-DWI序列图像主观评分为1.99分,优秀率18%,RESOLVE-DWI序列图像评分为3.31分,优秀率80%,差异有统计学意义(P<0.001),且2位诊断医师的评分一致性较好。RESOLVE-DWI序列相对EPI-DWI序列图像的信噪比(SNR),对比噪声比(CNR)明显提高,且具有统计学意义。结论RESOLVE-DWI序列可以显著改善图像质量,利于病灶的显示。     

3.0T磁共振乳腺成像扫描参数的优化

目的 探讨不同参数对乳腺MRI图像质量及扫描时间的影响.方法 (1)采用GE Signa Excite 3.0T MR成像系统和8通道乳腺线圈,对3个新鲜手术乳腺标本进行多序列、多参数扫描,根据图像质量及扫描时间选择适合乳腺MR成像的扫描序列和参数.(2)对10名健康志愿者采用FSE-IR、抑脂和非抑脂 FSE-XL T1WI和抑脂FSE-XL T2WI序列及不同参数进行乳腺MR成像,测量比较不同参数图像的信噪比.结果 其它参数相同时,采用以下序列和参数进行乳腺MR成像可在较短的扫描时间内获得较高的图像质量,包括FSE-IR序列:TR 6000 ms、TI 190 ms、TE 42 ms、带宽62.50 kHz、NEX 1、扫描层数18;FSE-XL T1WI序列:TR 500 ms、TE 11.5 ms、带宽50 kHz、NEX 2、扫描层数18;FSE-XL T2WI序列:TR 4200 ms、TE 80 ms、带宽41.67 kHz、NEX 1、扫描层数18.结论 3.0T MR乳腺成像,通过扫描参数的优化可节约扫描时间、提高图像质量.     

1.5T与3.0T MR正常肝脏扩散成像的比较研究

目的:分析比较1.5T与3.0T MR屏气扩散加权成像(DWI)对正常肝实质显示的图像质量及ADC值的影响.方法:分析16例无肝脏疾病的患者的1.5T与3.0T MR的DWI图像资料,b值为0.500s/mm2,对图像质量进行3级主观评分,并计算肝左右叶的信噪比(SNR)、与肌肉的对比噪声比(CNR)及ADC值并进行统计分析.结果:1.5T的图像质量主观评分优于3.0T (2.60 vs 2.20,P=0.0312).肝左叶、右叶在1.5T MR的平均SNR值均高于3.0T,并有显著统计学差异(左叶:47.9 vs 32.8,P=0.0018,右叶:46.2 vs 27.4,P=0.0004).而肝左叶、右叶与肌肉的平均CNR值1.5T略高于3.0T,而平均ADC值1.5T略低于3.0T,均无统计学差异无统计学差异(P＞0.05).结论:1.5T与3.0T MR-DWI正常肝脏ADC值相似,而图像质量3.0T不如1.5T.     

探讨复合灵敏度编码弥散加权成像在乳腺疾病中的应用价值

目的：通过复合灵敏度编码(MUSE)的弥散加权成像(DWI)和单次激发回波平面(SS-EPI)弥散加权成像的对比研究，探讨MUSE在乳腺疾病诊断中的应用价值。方法：分析2020年9月至2021年2月于本院行乳腺MRI检查的患者43例，所有患者在常规平扫及动态增强扫描的基础上，分别采用单次平面激发回波成像(SS-EPI)及MUSE方式采集DWI图像。由2名观察者采用双盲法对图像进行视觉定性评估，评估指标主要包括病灶显示性、病灶形变、病灶边缘清晰度。定量分析主要包括两序列的表观弥散系数(ADC)和信噪比(SNR)、对比噪声比(CNR)等图像质量参数的比较。结果：视觉定性分析结果显示，MUSE DWI比SS-EPI DWI有更好的病灶边缘清晰度、显示度及更低的病灶形变(P<0.05)。定量分析结果显示，与SS-EPI DWI相比，MUSE DWI在乳腺形变及SNR与CNR方面显著提高了图像质量(P<0.05)。MUSE DWI测得47个病灶ADC值[(1.23±0.30)×10^-3 mm²/s]低于SS-EPI DWI[(1.32±0....     

直肠癌MUSE-DWI与常规DWI成像对比研究

目的:对比分析基于复合灵敏度编码的高分辨率磁共振扩散成像(MUSE-DWI)与常规扩散加权成像(DWI)在直肠癌的成像质量。方法:回顾性纳入分析桂林医学院附属医院2021年11月-2022年6月经病理确诊为直肠癌的48例患者资料,采用3.0T磁共振进行常规序列扫描,以及进行MUSE-DWI和单次激发自旋回波平面成像(SS-EPI)图像对比研究。由2名放射科医师分别对2组DWI图像进行主观和客观评价。主观评价：采用5分法对病变可见性、病灶变形、轮廓清晰度、伪影水平以及图像噪声进行评分。客观评价：对信噪比(SNR)、对比度(CR)、表观扩散系数(ADC)以及病灶最大横纵径测量计算。主观评分一致性采取Kappa检验,以及采取配对t检验、Wilcoxon秩和检验比较图像质量客观评分之间的差异。结果:MUSE-DWI在病变可见性、几何变形、轮廓清晰度、磁敏感伪影以及图像整体质量的评分均高于SS-EPI DWI,差异具有统计学意义(P<0.001)。客观评价得出MUSE-DWI的SNR、CNR均优于常规DWI(P<0.001),2组DWI间的ADC值差异无统计学意义(P=0.55),并...     

TGSE BLADE DWI与RESOLVE DWI不同MR序列对中耳胆脂瘤图像质量的对比分析

目的 探讨分析刀锋技术快速梯度自旋回波扩散加权成像(TGSE BLADE DWI)与分段读出平面回波扩散加权成像(RESOLVE DWI)在中耳胆脂瘤的图像质量差异。方法 选取经手术证实的中耳胆脂瘤患者44例，所有患者术前均行TGSE BLADE DWI、RESOLVE DWI、常规颞骨MR平扫及增强检查，将DWI图像依据扫描方法分为两组进行图像质量评价，由2位影像诊断医师分别从磁敏感伪影、图像失真变形、整体图像质量及病变清晰度4个方面进行评分，测算两组DWI图像的信噪比(SNR)、对比度及对比噪声比(CNR)。2位医师对图像评分情况进行Kappa一致性检验，图像评分的组间比较采用Wilcoxon符号秩检验，SNR、对比度及CNR的组间比较采用配对样本t检验。结果 两组DWI图像间磁敏感伪影、图像失真变形、整体图像质量及病变清晰度的评分差异有统计学意义(P<0.001),TGSE BLADE DWI组图像的评分高于RESOLVE DWI组。两组DWI图像间SNR的差异有统计学意义(P<0.05),TGSE BLADE DWI的SNR低于RESOLVE DWI,对比度及CNR...     

肺结节磁共振扩散加权成像技术优化

目的:探讨采用容积匀场和矩形视野采集技术的磁共振扩散加权(DWI)扫描方式进行肺结节成像的价值.方法:连续的25例肺结节患者纳入研究,采用3.0T MRI超导成像仪(Philips Achieva 3.0T TX)进行DWI,先进行常规扫描(普通匀场、正方形视野采集),然后改进方式扫描(容积匀场、矩形采集),B值为0、300、600、900和1200s/mm2.两位资深胸部影像医生和一位技师共同评价两组图像,测量各组图像的AppCNR、SNR以及肺结节ADC值,并统计分析.结果:改进组图像质量主观评分(2.56±0.04)高于常规组(1.52±0.06) (P＜0.05).改进组各B值图像的AppCNR和SNR均对应显著高于常规组(P＜0.05).两组间的ADC值无显著性差异(P＞0.05).结论:附加容积匀场并减小相位方向视野的DWI扫描方式可以提高图像质量且不影响ADC值.     

膀胱癌ss-EPI-、RESOLVE-和iShim-DWI图像质量的对比

目的:对比分析膀胱癌术前ss-EPI、RESOLVE和iShim序列DWI的图像质量,探讨iShim-DWI在膀胱癌术前诊断中的应用价值。方法:回顾性分析经手术病理证实的97例膀胱癌患者(其中51例有明确的膀胱壁肌层浸润情况的病理结果)的MRI数据。所有患者术前在3.0T磁共振仪上分别采用ss-EPI、RESOLVE和iShim序列行横轴面DWI扫描。由两位观察者独立对3种DWI序列的图像质量进行定性和定量评估,同时观察和记录肿瘤是否侵犯膀胱壁肌层。定性评估使用李克特量表5分法,评价内容包括解剖细节(膀胱轮廓和边缘)、图像失真、病变显著性(肿瘤信号强度)、伪影和整体图像质量;定量测量指标包括病灶的信噪比(SNR)、对比噪声比(CNR)和ADC值。采用Kappa检验分析观察者组间及组内图像质量评分的一致性,3种DWI序列图像质量定性评估结果的比较采用Friedman M秩和检验,定量评估的比较采用单因素方差分析和SNK-q检验,采用卡方检验和ROC曲线评估3种序列对膀胱癌肌层浸润的诊断效能。结果:图像质量各项主观评分结果的观察者组间一致性为良好～好(Kappa≥0.75,P<0.0...     

iShim-EPI和SS-EPI在甲状腺结节扩散加权成像的应用比较

【摘要】目的：探讨单层动态匀场技术在3.0T MR仪甲状腺结节扩散加权成像中提高图像质量的可行性。方法：24例超声已明确诊断为甲状腺结节的患者共32个结节，对其进行单层动态匀场技术（iShim-EPI）和常规单次激发平面回波成像（SS-EPI）两种不同扩散加权成像（DWI）扫描。以横轴面T2WI抑脂图像为参考，两位放射科医师采用5分法对两种DWI序列图像的正常解剖结构显示能力、伪影及图像整体质量进行主观评分。评价2名医师主观评分的一致性使用Kappa检验，比较两种不同弥散序列对图像的正常解剖结构显示能力、伪影及图像整体质量的差异使用Wilcoxon检验。另由同一名放射医师通过绘制感兴趣区（ROI）对甲状腺结节进行定量参数的测量，计算甲状腺结节图像的信噪比（SNR),对比噪声比（CNR)及甲状腺结节前后（AP）、左右(RL)径几何变形率（GDR），测量甲状腺结节表观扩散系数（ADC）值，使用配对样本t检验比较两种不同扩散序列甲状腺结节定量参数的差异。结果：在iShim-EPI 和SS-EPI两种不同扩散序列中对甲状腺结节的正常解剖结构显示能力、伪影及图像整体质量两名医师的一致性均较好（Kappa值均>0.70）。医师二对SS-EPI和iShim-EPI序列图像显示甲状腺结节正常解剖评分分别为2.62、4.71，伪影评分分别为3.09、1.09，图像整体质量评分分别为2.21、4.53，各项评分两两之间差异均有统计学意义（P均<0.05）。两种序列图像定量参数比较，iShim-EPI序列甲状腺结节图像的 SNR、CNR分别为45.89、24.36，SS-EPI序列甲状腺结节图像的 SNR、CNR分别为11.01、5.38，两种序列间SNR、CNR差异均有统计学意义（P<0.05）。iShim-EPI序列的甲状腺结节图像前后和左右方向 GDR分别为8.02、4.02，SS-EPI序列的甲状腺结节图像前后和左右方向 GDR分别为39.42、27.66，iShim-EPI序列甲状腺前后、左右变形率较SS-EPI显著降低（P<0.001）。iShim-EPI序列和iShim-EPI 序列的甲状腺结节〖JP3〗ADC值分别为1.15×10-3mm2/s、1.11×10-3mm2/s，差异无统计学意义（P>0.05）。结论：iShim-EPI可以明显提高甲状腺结节的DWI图像质量。     

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.