The Application Value of Background Suppression Diffusion Weighted Imaging (DWIBS) in Preoperative Staging of Rectal Cancer

目的 探讨全身磁共振背景抑制扩散加权成像(DWIBS)对直肠癌术前分期的应用价值.资料与方法 对39例经肠镜证实的直肠癌患者,术前行全身磁共振DWIBS检查,以直肠癌原发灶病理结果为标准将本组资料分为T2、T3、T4三组,分析原发灶DWIBS上肿瘤信号强度、表观扩散系数(ADC)值、肠壁病变厚度、肠壁受累长度、肿瘤侵犯肠周径的情况五个指标在各组间的差异,及其与T分期的相关性.通过全身DWIBS图像作出术前NM分期,然后与术后NM病理分期结果进行对照,判断DWIBS对直肠癌NM分期的准确性、特异性及敏感性.结果 全身DWIBS对直肠癌原发灶检出的敏感性为100％,准确性为100％,DWIBS上所显示的肠壁病变厚度和肠周径侵犯程度在各分期间有显著差异(P＜0.05),且两者与T分期均有显著相关性(rs =0.427,P＜0.05;rs =0.384,P＜0.05);原发灶肿瘤信号强度、ADC值、肠壁受累长度在各分期间均无显著差异(P＞0.05).DWIBS对N分期诊断的总体准确性为84.61％;对N0期诊断的敏感性为85.71％,特异性为83.33％,N1期诊断的敏感性为70.00％,特异性为89.66％,N2期诊断的敏感性为100％,特异性为80.65％.对M期诊断的敏感性及准确性均为100％.结论 全身DWIBS对直肠癌NM分期的诊断敏感性较高,是显示转移性淋巴结及远处转移病灶的一种有效检查方法.全身DWIBS对直肠癌原发灶检出的准确性及敏感性很高,但在T分期中的应用有一定的限度,结合常规MRI序列有助于提高T分期的准确性.     

全身磁共振背景抑制扩散成像对胃癌原发病灶筛查及N分期的价值

目的 探讨全身MR背景抑制扩散成像(whole-body diffusion weighted imaging with background suppression,WB-DWIBS))对胃癌原发病灶筛查及N分期的价值.方法 选取经手术或胃镜活检病理证实的胃癌患者20例作为研究组,另随机选取健康者17名作为对照组,行常规MRI和WB-DWIBS检查.测量胃癌及正常胃壁的信号强度及表观扩散系数(ADC)值,同时计数WB-DWIBS发现的转移淋巴结的个数.结果 胃癌在高b值WB-DWIBS上表现为较高信号,与正常胃壁相比,其信号强度明显高于正常胃壁的信号强度(P＜0.05),ADC值明显小于正常胃壁的ADC值(P＜0.05).低分化腺癌与中分化腺癌间的信号强度与ADC值差异均无统计学意义(P＞0.05).WB-DWIBS对转移淋巴结分期N0期的敏感性为33.3％,特异性为64.3％；N1期的敏感性为57.1％,特异性为53.8％；N2期的敏感性为71.4％,特异性为46.2％.结论 WB-DWIBS可快速发现胃癌,对胃癌的全身筛查和早期诊断具有重要意义；对胃癌的N分期亦有重要价值.     

DWIBS 对直肠癌淋巴结转移的初步研究

目的：探讨背景信号抑制扩散加权成像(DWIBS)在直肠癌淋巴结转移诊断中的应用价值。方法30例经肠镜确诊的直肠癌患者行常规 MRI 及 DWIBS 检查。对照术后病理结果,确定转移性和非转移性淋巴结。测量淋巴结实质部分的表观扩散系数(ADC)值,比较差异有无统计学意义,采用受试者工作特征曲线(ROC)分析确定 ADC 值的诊断阈值。结果73枚淋巴结中,转移性淋巴结52枚,非转移性淋巴结21枚。转移性与非转移性淋巴结实质部分的 ADC 值分别为(0.881±0.094)×10-3 mm2/s和(1.072±0.108)×10-3 mm2/s,差异有统计学意义(P <0.05)。当以 ADC=0.957×10-3 mm2/s 作为鉴别转移性与非转移性淋巴结的诊断指标,其诊断价值为优(Az 值=0.919,P <0.05),灵敏度为90.5%,特异度为80.8%。结论ADC 值可用于直肠癌淋巴结转移的鉴别,DWIBS 在直肠癌淋巴结转移的评估中具有较高的应用价值。     

磁共振全身弥散成像对结直肠癌原发病灶筛查的价值

目的:探讨磁共振全身弥散成像(WB-DWI)对结直肠癌原发病灶筛查方面的价值.方法:对已经确诊的结直肠癌患者43例作为研究组,另随机选取健康人群10例,痔疮患者8例,息肉患者10例作为对照组,进行常规MRI及WB-DWI检查,进行常规MRI、WB-DWI、手术、病理资料对比研究分析.结果:结直肠癌在WB-DWI上表现为较高信号,与正常肠管相比,其DWI信号强度明显高于正常肠壁的信号强度(P＜0.05),其ADC值明显小于正常肠壁的ADC值(P＜0.05).WB-DWI最终正确诊断68例,3例假阳性诊断,0例假阴性诊断.WB-DWI对结直肠癌原发病灶检出的敏感性为100%(43/43),特异性为89%(25/28),诊断准确性为96%(68/71).结论:WB-DWI可以快速发现结直肠癌,对结直肠癌的全身筛查和早期诊断方面具有重要意义.     

全身磁共振背景抑制扩散成像在直肠癌术前分期中的应用价值

目的探讨全身磁共振背景抑制扩散加权成像(DWIBS)对直肠癌术前分期的应用价值。资料与方法对39例经肠镜证实的直肠癌患者,术前行全身磁共振DWIBS检查,以直肠癌原发灶病理结果为标准将本组资料分为T2、T3、T4三组,分析原发灶DWIBS上肿瘤信号强度、表观扩散系数(ADC)值、肠壁病变厚度、肠壁受累长度、肿瘤侵犯肠周径的情况五个指标在各组间的差异,及其与T分期的相关性。通过全身DWIBS图像作出术前NM分期,然后与术后NM病理分期结果进行对照,判断DWIBS对直肠癌NM分期的准确性、特异性及敏感性。结果全身DWIBS对直肠癌原发灶检出的敏感性为100%,准确性为100%,DWIBS上所显示的肠壁病变厚度和肠周径侵犯程度在各分期间有显著差异(P<0.05),且两者与T分期均有显著相关性(rs=0.427,P<0.05;rs=0.384,P<0.05);原发灶肿瘤信号强度、ADC值、肠壁受累长度在各分期间均无显著差异(P>0.05)。DWIBS对N分期诊断的总体准确性为84.61%;对N0期诊断的敏感性为85.71%,特异性为83.33%,N1期诊断的敏感性为70.00%,特异性为89.66%,N2期诊断的敏感性为100%,特异性为80.65%。对M期诊断的敏感性及准确性均为100%。结论全身DWIBS对直肠癌NM分期的诊断敏感性较高,是显示转移性淋巴结及远处转移病灶的一种有效检查方法。全身DWIBS对直肠癌原发灶检出的准确性及敏感性很高,但在T分期中的应用有一定的限度,结合常规MRI序列有助于提高T分期的准确性。     

背景抑制磁共振扩散成像技术在肝占位及转移淋巴结成像的应用研究

目的 探讨背景抑制扩散成像(diffusion weighted imaging with background suppression,DWIBS)技术在肝脏占位及转移淋巴结成像的应用研究. 资料与方法 对26例肝脏占位患者行常规MRI及DWIBS检查,分别测量肿瘤实质、瘤内坏死区域、转移淋巴结及正常肝实质的表观扩散系数值(ADC值).行3D 最大密度投影(MIP)重组及黑白翻转技术观察瘤体与淋巴结的信号特点. 结果 肿瘤实质、瘤内坏死区域、转移淋巴结及正常肝实质的平均ADC值分别为(0.873±0.38)× 10-3 mm2/s、(2.12±0.48) × 10-3 mm2/s、(0.856±0.41)× 10-3 mm2/s、(1.296±0.67) ×10-3 mm2/s;肿瘤实质与瘤内坏死灶间ADC值有统计学差异(P＜0.05),肿瘤实质与正常肝实质间ADC值有统计学差异(P＜0.05),肿瘤实质与肿大淋巴结间ADC值的差异无统计学意义(P＞0.05).DWIBS瘤灶显示率96.1%,淋巴结显示率94.7%.瘤灶与肿大淋巴结呈高信号,反转图呈低信号. 结论 背景抑制扩散成像可以通过ADC值对肝脏占位及转移淋巴结量化,并能直观地、立体地、多角度观察淋巴结的分布.     

背景抑制扩散加权成像诊断头颈部鳞癌颈部淋巴结转移的价值

目的 前瞻性地探讨背景抑制扩散加权成像(DWIBS)评价头颈部鳞癌颈部淋巴结转移的临床应用价值.方法 对20例经颈部淋巴结活检或手术病理证实的头颈部鳞癌患者(舌癌5例、鼻咽癌5例、喉癌3例、口底癌3例、口咽癌1例、喉咽癌1例、面颊癌1例和唇癌1例)进行颈部常规MR和DWIBS扫描,测量淋巴结的ADC值,选定鉴别转移性和良性淋巴结的最佳ADC阈值,并比较DWIBS与常规MRI显示和诊断转移性淋巴结的能力.两组均数间的比较采用独立样本t检验.结果 常规MR检查计数淋巴结共101枚,诊断转移性淋巴结58枚;常规MRI诊断淋巴结转移的敏感度为78%(47/60)、特异度为81%(44/54)、准确度为80%(91/114)、阳性预测值为82%(47/57)、阴性预测值为77%(44/57).DWIBS计数淋巴结共114枚,转移性淋巴结(60枚)的平均ADC值为(0.945±0.122)×10-3mm2/s,低于良性淋巴结(54枚)的平均ADC值(1.210±0.151)×10-3 mm2/s(t=-10.354,P＜0.01).以1.090×10-3 mm2/s作为ADC阈值,诊断颈部淋巴结转移的敏感度、特异度、准确度、阳性和阴性预测值分别为88%(53/60)、80%(43/54)、84%(96/114)、83%(53/64)和86%(43/50).结论 DWIBS有助于诊断头颈部鳞癌的颈部淋巴结转移,较常规MRI可提高其检出率.     

磁共振扫描在胃癌术前TN分期中的应用研究

目的:评价磁共振在胃癌术前TN分期中的价值.方法:26例经胃镜活检确诊的患者术前行磁共振成像,MR动态增强图像、DWI图像对胃癌术前TN分期评估,并与术后病理结果对照.结果:MR对胃癌T分期诊断的准确率为76.9％.MR对胃周转移淋巴结的检出率为41.8％,胃癌病变的表面扩散系数(ADC)值较相应正常胃壁的ADC值偏低(P =0.145).胃癌病变ADC值与浆膜浸润差异有统计学意义(P =0.036＜0.05).结论:MRI能对胃癌术前TN分期做出准确的判断.DWI对于胃癌病灶以及其淋巴结转移的判断具有较高的影像诊断学价值.     

DWIBS和全脊柱MR成像对脊柱恶性肿瘤的诊断研究

目的 探讨磁共振背景抑制弥散加权成像(DWIBS)在脊柱恶性肿瘤早期诊断中临床应用价值.方法 60例临床证实为恶性肿瘤患者行全身弥散加权成像检查,并于同一时间对可疑部位行常规磁共振成像检查,必要时增强扫描,诊断结果与临床综合评价结果进行比较,分别比较DWIBS和常规磁共振成像所显示的病例数.结果 60例患者中55例经临床综合评价为脊柱转移瘤.常规MRI联合DWIBS检查的敏感性、特异性、阳性预测值、阴性预测值分别为98.8％、99.4％、95.4％、99.8％.与常规MRI及DWIBS比较,P＜0.05有统计学意义.结论 DWIBS在恶性肿瘤脊柱转移瘤早期诊断中具有一定的应用价值,结合常规MRI检查可进一步明确诊断.     

肺部疾病MR背景抑制扩散成像应用初探

目的 初步评价MR背景抑制扩散成像(DWIBS)最大密度投影(MIP)图像及表观扩散系数(ADC)值的定量测量在肺部疾病中的应用价值.方法 61例患者接受了肺部DWIBS,其中肺癌38例,肺部炎性病变23例,分析肺部疾病三维(3D)MIP重组图像表现,确定肺部病变的ADC值范围,评价DWIBS对肺部疾病的诊断价值.结果 DWIBS上肺癌及炎性病变表现为不同形态的信号强度密集区域.DWIBS上中央型肺癌平均ADC值为(1.05±0.23)×10-3 mm2/s,周围型肺癌平均ADC值为(1.10±0.17)×10-3 mm2/s,各种炎性病变平均ADC值为(1.69±0.29)×10-3 mm2/s,周围型肺癌与炎性病变的平均ADC值差异有统计学意义(P＜0.05).3.0 T MRI+DWIBS对肺部疾病诊断的敏感性、特异性及准确性(分别为86.84%、82.60%和85.24%)高于单纯MRI诊断(分别为78.94%、78.26%和78.68%).结论 DWIBS能够立体、直观地显示病灶,实现了肺部病变ADC值的定量测量,有望成为肺部疾病鉴别诊断的方法之一.     

A monitoring,feedback, and triggering system for reproducible breath-hold MR imaging

A technique is described that provides improved reproducibility of breath-holding for MR image acquisition by monitoring the superior-inferior (S/I) position of the diaphragm. The method incorporates detection of the level of inspiration using an MR signal, rapid display to the patient of diaphragm position to enable breath-hold adjustment, and triggering of image data acquisition once appropriate position is attained. The response time of the system is short, approximately 10 ms. Studies in six volunteers using this method demonstrate a considerable decrease in the S/I range of diaphragm position over 10 consecutive periods of suspended respiration. The mean range is 1.3 mm with the system, while it is 8.3 mm without using it is expected that this method will be of assistance in many abdominal and cardiothoracic studies that use breath-hold techniques.     

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。     

RARE spiral T2-weighted imaging

Spiral imaging has a number of advantages for fast imaging, including an efficient use of gradient hardware. However, inhomogeneity-induced blurring is proportional to the data acquisition duration. In this paper, we combine spiral data acquisition with a RARE echo train. This allows a long data acquisition interval per excitation, while limiting the effects of inhomogeneity. Long spiral k-space trajectories are partitioned into smaller, annular ring trajectories. Each of these annular rings is acquired during echoes of a RARE echo train. The RARE refocusing RF pulses periodically refocus off-resonant spins while building a long data acquisition. We describe both T₂-weighted single excitation and interleaved RARE spiral sequences. A typical sequence acquires a complete data set in three excitations (32 cm FOV, 192 × 192 matrix). At a TR = 2000 ms, we can average two acquisitions in an easy breath-hold interval. A multifrequency reconstruction algorithm minimizes the effects of any off-resonant spins. Though this algorithm needs a field map, we demonstrate how signal averaging can provide the necessary phase data while increasing SNR. The field map creation causes no scan time penalty and essentially no loss in SNR efficiency. Multiple slice, 14-s breath-hold scans acquired on a conventional gradient system demonstrate the performance.     

Echo-Time-Encoded Burst Imaging (EBI): A Novel Technique for Spectroscopic Imaging

A new technique for rapid spectroscopic imaging is presented. The proposed experiment enables a complete mapping of the two-dimensional reciprocal space k_x, k_o, and thus the acquisition of a 1D spectroscopic image in a single scan. The properties of the pulse sequence, based on the use of a burst of low flip angle pulses, are analyzed in the framework of linear response theory, and it is shown that chemical shift information may be introduced into the spatially encoded echoes. First experimental results are presented demonstrating that 32 x 32 proton spectroscopic images may be acquired within less than 1 min with a conventional imaging system.     

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.     

Simultaneous multislice (SMS) imaging techniques

Simultaneous multislice imaging (SMS) using parallel image reconstruction has rapidly advanced to become a major imaging technique. The primary benefit is an acceleration in data acquisition that is equal to the number of simultaneously excited slices. Unlike in‐plane parallel imaging this can have only a marginal intrinsic signal‐to‐noise ratio penalty, and the full acceleration is attainable at fixed echo time, as is required for many echo planar imaging applications. Furthermore, for some implementations SMS techniques can reduce radiofrequency (RF) power deposition. In this review the current state of the art of SMS imaging is presented. In the Introduction, a historical overview is given of the history of SMS excitation in MRI. The following section on RF pulses gives both the theoretical background and practical application. The section on encoding and reconstruction shows how the collapsed multislice images can be disentangled by means of the transmitter pulse phase, gradient pulses, and most importantly using multichannel receiver coils. The relationship between classic parallel imaging techniques and SMS reconstruction methods is explored. The subsequent section describes the practical implementation, including the acquisition of reference data, and slice cross‐talk. Published applications of SMS imaging are then reviewed, and the article concludes with an outlook and perspective of SMS imaging. Magn Reson Med 75:63–81, 2016. © 2015 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance.     

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).     

Temporal resolution improvement in dynamic imaging

In some dynamic imaging applications, only a fraction, 1/n, of the field of view (FOV) may show considerable change during the motion cycle. A method is presented that improves the temporal resolution for a dynamic region by a factor, n, while maintaining spatial resolution at a cost of √n in signal-to-noise ratio (SNR). Temporal resolution is improved, or alternatively, total imaging time is reduced by reducing the number of phase encodes acquired for each temporal frame by 1/n. To eliminate aliasing, a representation of the signal from the static outer portion of the FOV is constructed using all the raw data. The k-space data derived from this representation is subtracted from the original data sets, and the differences correspond to the dynamic portion of the FOV. Improved resolution results are presented in phantom studies, and in vivo phase contrast quantitative flow imaging.