前列腺成像:可重复使用的双通道直肠内接收线圈在1.5TMR中的应用价值

正目的前瞻性对比分析目前广泛应用于1.5 T MRI前列腺检查的双通道固态可重复使用直肠内相控阵接收线圈(SPAC)与单通道直肠内充气线圈的成像质量差异。材料     

The Application Value of MRI PDW PFS Sequence in the Perianal Fistulas

目的 评价质子加权预饱和脂肪抑制序列( PDW PFS)对肛瘘显示的准确性及图像质量的清晰性,探讨PDWPFS在肛瘘中的应用价值.资料与方法 20例经手术证实的肛瘘患者术前进行MRI检查,序列包括T1WI、T2W频谱选择性衰减反转恢复序列(SPAIR)和PDW PFS.MRI检查前均向患者肛管直肠内置入肛肠水囊以撑开肛管和直肠.获得图像后,观察患者的瘘管、内口和肛周脓肿,评估和比较MRI各序列显示的瘘管、内口、脓腔,并对PDW PFS和T2WSPAIR序列瘘管的信号强度(SI)、信噪比(SNR)及瘘管与周围肌肉的对比噪声比(CNR)进行测量及比较.结果PDW PFS序列显示瘘管(100％)、内口(95.7％)、肛周脓肿(100％)的准确率较T1WI及T2WSPAIR序列为高.KruskalWallis检验显示上述各序列对瘘管(x2=6.95,P＜0.05)及内口(x2=31.53,P＜0.05)的显示具有显著统计学差异,PDW PFS序列显示瘘管及内口最多.PDW PFS序列SI、SNR值和CNR值均显著高于T2WSPAIR序列(P＜0.05).结论 PDW PFS成像技术具有较高的图像SNR和CNR,更易认识辨别瘘管和内口,可以作为一种新的无创性磁共振成像技术应用于肛瘘成像.     

前列腺癌的MRI检查

前列腺癌是欧美国家最常见的恶性肿瘤之一 ,国内发病率也在逐步上升[1 ] 。本文就近年来 MRI有关前列腺癌的文献作一综述。1　前列腺癌 MRI检查的设备与技术前列腺检查常需薄层扫描及小显示野 ,高场磁共振机图像质量高 ,而低中场磁共振机信噪比较低成像质量不佳。直肠表面线圈可使前列腺图像分辨率明显提高 ,得以观察前列腺及周围结构的详尽图像 ,但因其显示范围较小 ,故还需体线圈检查盆腔腹部以显示骨盆淋巴结等病变。盆腔相控阵线圈可进一步提高图像质量。多数文献认为直肠表面线圈结合其他设备为评价前列腺病变的最佳方法[2～ 4] 。…     

Initial application of dual energy CT in enterography: monochromatic images of normal intestinal wall

目的:探讨双能CT小肠成像单能量图像显示正常回肠壁的成像质量及其与混合能量图像在小肠CT成像中的差异.方法:对18例拟诊为炎症性肠病患者行小肠CT成像(CTE),采用双能CT宝石能谱成像技术行CT平扫及双期增强扫描(实质期和延迟期),将实质期图像数据分别进行混合能量和GSI单能量重建,应用能谱分析软件,获得正常回肠壁最佳对比噪声比(CNR)单能图像的KeY值.计算混合能量和单能图像上正常回肠壁的对比噪声比,测量两种图像的噪声并进行配对t检验;由两位医师对两种图像上主动脉锐利度、噪声和图像质量进行主观评分并进行配对t检验,计算组内相关系数来评价观察者间的一致性.结果:正常回肠壁最佳CNR单能量为(56.67±5.04)KeV;单能图像正常回肠壁的CNR高于混合能量(分别为4.36±0.71和3.34±0.78,t=4.702,P＜0.01),脂肪组织的图像噪声高于混合能量图像(分别为16.87±2.73和14.58±2.26,t=3.85,P＜0.01),液体区域的噪声也高于混合能量图像(分别为16.08±4.17和13.51±2.85,t=4.96,P＜0.01);混合能量和单能图像的锐利度评分分别为3.08±0.50和2.97±0.38、图像质量评分分别为2.92±0.28和2.94±0.23,差异均无显著性意义(P=0.32,P=0.66),单能图像噪声评分低于混合能量(分别为2.36±0.49和2.75±0.44,t=3.62,P＜0.01);两位医师评价单能图像质量和混合能量图像噪声的一致性好(r分别为1.00和0.42).结论:双能CT最佳CNR单能图像评价正常回肠壁有较好的对比噪声比和成像质量.     

能谱CT显示前列腺病灶的最佳单能量研究

目的:运用能谱CT研究显示前列腺病灶的最佳单能量值及其图像质量分析.方法:回顾性分析28例前列腺外周带病变患者的临床和影像资料,共发现38个病灶,包括前列腺癌20个、前列腺增生18个.患者均行三期动态增强(动脉期、静脉期及实质期)CT能谱成像,在140 kVp混合能量图像和40～140 KeV各组单能量图像上测量和计算病灶的对比噪声比(CNR),记录每个病灶CNR最高的图像所对应的KeV值,每个病灶测量3次(选取3个不同层面),计算其均值.对不同期相的140 kVp图像和50 keV图像进行图像质量的主观评分(5级评分法)和客观评价(CNR),两组间比较采用配对t检验.结果:统计分析结果显示前列腺病灶的最佳单能量值为(50.7±1.53) keV.不同期相50 keV图像的主观评分分别为3.88±0.64、3.88±0.64和3.63±0.74,140 kVp图像的相应评分分别为2.63±0.52、2.88±0.64和2.50±0.54.病灶在不同期相50 keV图像上的CNR(32.42±5.06、36.02±5.80和34.97±4.14)均高于140 kVp图像(13.45±3.53、20.86±4.34和21.14±3.41),差异均有统计学意义(P＜0.05).结论:能谱CT检查显示前列腺病灶的最佳单能量值为50 keV,其图像质量明显优于普通混合能量图像,有利于前列腺外周带病灶的检出.     

对比正交鸟笼线圈与CTL脊柱线圈颅脑MR图像质量

目的探讨正交鸟笼线圈与CTL脊柱线圈在颅脑扫描中的应用价值。方法采用MRI所配备的正交鸟笼头线圈和CTL脊柱线圈对标准ACR水模行轴位T₁FLAIR序列扫描,对每层图像的信噪比(SNR)及均匀度百分比(PIU)进行测量计算,并对其结果进行配对t检验。随机抽取使用头颅正交鸟笼线圈和CTL脊柱线圈进行颅脑检查的100例患者,分别对其图像SNR及图像质量评分对比分析。结果1)CTL脊柱线圈的SNR优于正交鸟笼线圈;正交鸟笼线圈的PIU优于CTL脊柱线圈,两组间差异均具有统计学意义(P<0.05);2)正交鸟笼线圈及CTL脊柱线圈的图像整体质量评分、伪影评分、病灶检出及序列评分差异均无统计学意义(P>0.05)。结论两种线圈均可以用于颅脑的检查扫描,但CTL脊柱线圈可获得更高SNR的图像,更有利于临床疾病的诊断。     

Application of dual energy CT in split-bolus 2-phase CT urography

目的:探讨分次团注双期CTU检查时双能CT成像的临床应用价值.方法:48例血尿待查患者分为两组,试验组24例,行全泌尿系CT平扫及分两次团注对比剂后行肾实质-肾盂期CTU扫描;对照组24例,行全泌尿系CT平扫及单次团注对比剂后行实质期和肾盂期双期增强扫描.实验组的肾实质-肾盂期图像的采集采用高低压瞬切双能CT扫描模式(GSI),其它所有期相的图像采集均采用普通CT扫描模式.在工作站上使用GSI后处理软件获得实质-肾盂期最佳keY图像.将CTU图像中集合系统分段,测量实验组的肾实质-肾盂期最佳keY图像和对照组的肾盂期图像中集合系统各段管腔内的CT值,并计算对比噪声比(CNR).记录所有病例完成CTU全部检查序列的有效辐射量.两组病例CT值、CNR和有效辐射量的比较使用非参数秩和检验.结果:分次团注CTU实质-肾盂期最佳keY图像各段集合系统腔内CT值均高于常规CTU肾盂期图像,其差异有统计学意义(P＜0.05).分次团注CTU实质-肾盂期最佳keV图像与常规CTU肾盂期图像各段集合系统CNR差异没有统计学意义(P＞0.05).分次团注CTU完成全部检查的有效辐射量(平均17.6 mSv)明显低于常规CTU(平均25.8mSv),差异有统计学意义(P＜0.05).结论:双能CT成像用于分次团注双期CTU在降低辐射量同时,可获得与常规单次团注双期CTU相同的泌尿系成像质量.     

质子加权预饱和脂肪抑制序列在肛瘘中的应用价值

目的评价质子加权预饱和脂肪抑制序列(PDW PFS)对肛瘘显示的准确性及图像质量的清晰性,探讨PDW PFS在肛瘘中的应用价值。资料与方法 20例经手术证实的肛瘘患者术前进行MRI检查,序列包括T1WI、T2W频谱选择性衰减反转恢复序列(SPAIR)和PDW PFS。MRI检查前均向患者肛管直肠内置入肛肠水囊以撑开肛管和直肠。获得图像后,观察患者的瘘管、内口和肛周脓肿,评估和比较MRI各序列显示的瘘管、内口、脓腔,并对PDW PFS和T2W SPAIR序列瘘管的信号强度(SI)、信噪比(SNR)及瘘管与周围肌肉的对比噪声比(CNR)进行测量及比较。结果 PDW PFS序列显示瘘管(100%)、内口(95.7%)、肛周脓肿(100%)的准确率较T1WI及T2WSPAIR序列为高。Kruskal Wallis检验显示上述各序列对瘘管(χ2=6.95,P<0.05)及内口(χ2=31.53,P<0.05)的显示具有显著统计学差异,PDW PFS序列显示瘘管及内口最多。PDW PFS序列SI、SNR值和CNR值均显著高于T2W SPAIR序列(P<0.05)。结论 PDW PFS成像技术具有较高的图像SNR和CNR,更易认识辨别瘘管和内口,可以作为一种新的无创性磁共振成像技术应用于肛瘘成像。     

不同射频线圈应用于三维磁共振涎管造影的对比研究

目的 通过对比研究探讨最适合于三维薄层磁共振涎管造影的射频线圈.方法 50名无涎腺病变志愿者,采用重T2加权FSE序列,固定TR、TE和其他扫描参数,依次应用头线圈、头颈联合线圈、C3表面线圈和SENSE-FLEX-M线圈进行扫描,对涎管的三维磁共振造影图像进行评分,计算涎管与背景组织间的对比噪声比(CNR),比较不同线圈组涎管的得分和CNR之间有无统计学差异.结果 不同线圈组的磁共振涎管造影图像的得分和CNR之间具有显著性差异(P<0.01).在腮腺管的显示上,头线圈组的得分和CNR显著低于其他各组,头颈联合线圈组的得分和CNR低于C1表面线圈组和FLEX-M线圈组(P<0.05),C3表面线圈组和FLEX-M线圈组之间无显著性差异(P>0.05).在颌下腺管的显示上,头线圈组的得分和CNR显著低于其他各组(P<0.01),其余各组之间无显著性差异(P>0.05).结论 在Philips Achieva 1.5T磁共振机上行三维重T2加权FSE磁共振涎管造影,应用SENSE-FLEX-M线圈既能保证获得高质量的涎管影像,又不会增加检查的复杂性,是最佳选择.     

前列腺和精囊磁共振扩散成像中EPI与SSFSE序列的比较

目的比较回波平面成像（EPI）与单次激发快速自旋回波（SSFSE）扩散成像序列测量前列腺和精囊的表观扩散系数（ADC）值. 资料与方法选择40例无前列腺和精囊疾病的男性,使用EPI和SSFSE扩散成像序列,行前列腺和精囊局部的磁共振扩散成像检查.两种脉冲序列的扩散敏感梯度（b）值均取1 000s/mm2.在工作站上测量前列腺中央带和外周带、精囊、膀胱、盆腔脂肪、直肠内气体的ADC值.对两种脉冲序列测得的组织ADC值使用配对t检验进行比较. 结果 EPI序列40名受检者中32例（80%）获得可测量ADC值的图像,SSFSE序列40例（100%）获得可测量ADC值的图像.两种扩散成像序列测得的膀胱、直肠内气体和盆腔脂肪的ADC值无统计学差异（P〉0.05）,而两种扩散成像序列测得的前列腺中央带、外周带、精囊的ADC值有统计学差异（P〈0.01）.EPI序列测得上述组织的ADC值较小. 结论不同扩散成像序列测得的前列腺中央带、外周带和精囊的ADC值有差异.     

Phased-array MRI of canine prostate using endorectal and endourethral coils.

A four-channel phased array consisting of one surface coil, two endorectal coils, and one flexible endourethral loop coil was designed for MRI of the canine prostate. The endorectal coils provide high signal in the posterior region of the prostate, while the endourethral and surface coils are sensitive to the central and anterior regions of the prostate. Gel phantom experiments indicate that the proposed phased-array configuration generates 15 times more signal-to-noise ratio (SNR) than a combination of two surface coils and one endorectal coil within the posterior region of the prostate; the performance of the two configurations is comparable near the anterior prostate surface. Ultimate intrinsic SNR (UISNR) analysis was used to compare the proposed phased array's performance to the best possible SNR for external coils. This analysis showed that the proposed phased array outperforms the best-case external coil within the posterior and central regions of the prostate by up to 20 times. In canine experiments in vivo, high-resolution fast spin-echo (FSE) images of the prostate were obtained with a pixel size of 230 microm obtained in 3 min 12 s. The proposed phased-array design potentially can be used to increase the accuracy of prostate cancer staging and the feasibility of MR-guided prostate interventions.     

Prostate MR imaging at 3T with a longitudinal array endorectal surface coil and phased array body coil

PURPOSE: To demonstrate the feasibility of using a double loop phased array endorectal coil combined with a phased array body coil to image the prostate at 3T. MATERIALS AND METHODS: We designed and constructed a novel prostate coil employing two arrayed 4.0 x 5.0 cm loops, tuned the device for optimal performance at 3T, and characterized the signal-to-noise ratio (SNR) associated with it. RESULTS: The coil Q factor was calculated to be approximately 50 unloaded, and 30 when loaded on human tissue. SNR maps at multiple orientations were constructed and images were acquired on both a phantom and a human. As expected, SNR was highest along the midpoint of the array and demonstrated strong signal even at 4 cm from the coil. CONCLUSION: The double loop phased array endorectal coil combined with a phased array body coil at 3T is feasible in vivo and compelling enough to warrant future clinical trials to evaluate its efficacy. These trials are currently under way.     

A solid reusable endorectal receiver coil for magnetic resonance imaging of the prostate: Design,use, and comparison with an inflatable endorectal coil

We have designed a solid endorectal receiver coil for MRI of the prostate. The coil provided an improved signal-to-noise ratio up to 5 cm from its surface when compared with a standard pelvic phased array. This preliminary report describes 16 patients who were imaged using this coil, seven of whom had been examined previously with a balloon-design endorectal coil. Patient tolerance of these coils was compared. The solid coil was easy to insert and quick to set up because it did not require external tuning and matching. It avoided uncomfortable rectal distension experienced with the balloon coil as well as susceptibility artifacts from air in the balloon. In addition, it could be sterilized and reused.     

Focused, eight-element transceive phased array coil for parallel magnetic resonance imaging of the chest--theoretical considerations.

A new transceive system for chest imaging for MRI applications is presented. A focused, eight-element transceive torso phased array coil is designed to investigate transmitting a focused radiofrequency field deep within the torso and to enhance signal homogeneity in the heart region. The system is used in conjunction with the SENSE reconstruction technique to enable focused parallel imaging. A hybrid finite-difference-time-domain/method-of-moments method is used to accurately predict the radiofrequency behavior inside the human torso. The simulation results reported herein demonstrate the feasibility of the design concept, which shows that radiofrequency field focusing with SENSE reconstruction is theoretically achievable.     

Specific coil design for SENSE: a six-element cardiac array.

In sensitivity encoding (SENSE), the effects of inhomogeneous spatial sensitivity of surface coils are utilized for signal localization in addition to common Fourier encoding using magnetic field gradients. Unlike standard Fourier MRI, SENSE images exhibit an inhomogeneous noise distribution, which crucially depends on the geometrical sensitivity relations of the coils used. Thus, for optimum signal-to-noise-ratio (SNR) and noise homogeneity, specialized coil configurations are called for. In this article we study the implications of SENSE imaging for coil layout by means of simulations and imaging experiments in a phantom and in vivo. New, specific design principles are identified. For SENSE imaging, the elements of a coil array should be smaller than for common phased-array imaging. Furthermore, adjacent coil elements should not overlap. Based on the findings of initial investigations, a configuration of six coils was designed and built specifically for cardiac applications. The in vivo evaluation of this array showed a considerable SNR increase in SENSE images, as compared with a conventional array. Magn Reson Med 45:495-504, 2001.     

Proton two-dimensional chemical shift imaging for evaluation of prostate cancer: external surface coil vs. endorectal surface coil

PURPOSE: To compare the diagnostic ability of proton magnetic resonance spectroscopy (MRS) using an external surface coil with that using an endorectal surface coil in patients with prostate cancer. MATERIALS AND METHODS: MR imaging (MRI) and two-dimensional chemical shift imaging (2D CSI) were performed in 5 healthy volunteers and in 35 patients with prostate cancer. The receiver coil was the anterior lower part of a phased-array coil or an endorectal surface coil. RESULTS: Receiver-operating characteristic analysis for diagnosing prostate cancer showed no significant difference (P = 0.784) between the area under the curve of phased-array coil CSI and that of endorectal surface coil CSI. CONCLUSION: The phased-array coil CSI could provide comparable detection accuracy to endorectal surface coil CSI. In patients with rectal diseases or patients who could not tolerate the discomfort with insertion of an endorectal surface coil, we recommend the phased-array coil CSI.     

Multiparametric MR imaging of the prostate at 1.5-T without endorectal coil using an 8 channel pelvic phased array: Is it still a viable option?

IntroductionThe purpose of our work was to evaluate the feasibility of prostate multiparametric MR imaging at 1.5-T without endorectal coil using an 8 channel pelvic phased array coil.Material and methodsA total of 154 patients who underwent mp-MRI were retrospectively included. Patients received a standardized mp-MRI, compliant with 2012 European Society of Uro-Radiology guidelines, with 1·5 T magnetic field strength and an 8 channel pelvic phased-array coil.Two blinded readers graded the image quality of mp-MRI on a three-point scale and they scored the prostate lesions according to PI-RADS v2. All PI-RADS of 4 or 5 underwent biopsy. A third radiologist and a pathologist verified the correspondence between the MRI images and the results of the biopsy.Results64 (41.6%) patients showed a Pi-rads of 4 or 5. At biopsy, 79.7% showed a Gleason score ≥7, 12.5% showed a Gleason score of 6 and 7.8% showed a negative biopsy. In the group of Pi-rads ≤ 3, 12 patients underwent a biopsy with the following results: negative biopsy in 33.3%, atypical Small Acinar Proliferation in 16.7%, prostatic intraepithelial neoplasia in 25% and indolent PCa 25%. Mp-MRI in the identification of clinically significant cancer provided a low percentage of false positive (7.8%) while in 79.7% of cases it was capable to detect clinically significant prostate cancer. In 92.2% of patients mp-MRI identified a prostate cancer with a Gleason score ≥6. The inter-reader agreement was excellent in defining both the quality of the examination and the PI-RADS category (k = 0.83 and k = 0.70, respectively).Conclusionsmp-MRI at 1.5-T without endorectal coil using an 8 channel phased array is an appropriate tool for early detection of clinically significant prostate cancer.Implications for practice8 channel pelvic phased array is still an appropriate tool for early detection of clinically significant prostate cancer and for obtaining a reduction in overdiagnosis of indolent PCa.     

MRI快速自旋回波序列和盆腔相控线圈对前列腺癌的诊断价值

评价快速自旋回波序列和盆腔相控线圈在前列腺癌ＭＲＩ诊断的价值。方法１４６例进行前殂朱ＭＲＩ检查,其中２４例应用常规ＳＥＴ２ＷＩ和体线圈;７０例应用ＦＳＥＴ２ＷＩ和体线圈;５２例应用ＦＳＥＴ２ＷＩ和盆腔相控线圈;比较３种扫描方法所获图像质量之间的差异和对前列腺癌诊断的准确性、敏感性、特异性、阳性预测值和阴性预测值。     

ESUR prostate MR guidelines 2012

The aim was to develop clinical guidelines for multi-parametric MRI of the prostate by a group of prostate MRI experts from the European Society of Urogenital Radiology (ESUR), based on literature evidence and consensus expert opinion. True evidence-based guidelines could not be formulated, but a compromise, reflected by “minimal” and “optimal” requirements has been made. The scope of these ESUR guidelines is to promulgate high quality MRI in acquisition and evaluation with the correct indications for prostate cancer across the whole of Europe and eventually outside Europe. The guidelines for the optimal technique and three protocols for “detection”, “staging” and “node and bone” are presented. The use of endorectal coil vs. pelvic phased array coil and 1.5 vs. 3 T is discussed. Clinical indications and a PI-RADS classification for structured reporting are presented.     

In vivo prostate magnetic resonance imaging and magnetic resonance spectroscopy at 3 Tesla using a transceive pelvic phased array coil: preliminary results

Magnetic resonance (MR) systems operating at 3 Telsa (T) and above have demonstrated considerable potential in human studies, offering improved signal-to-noise ratio and spectral resolution. However, because of radiofrequency limitations and concerns, and the lack of large volume body coils, most studies have been limited to the head. In this study we describe the design and construction of a transceive pelvic phased array coil with which MR images and spectra of the human prostate at 3 T have been obtained. Comparison with 1.5 T instruments with different hardware configurations is difficult; however, in a preliminary comparison the signal-to-noise ratio is improved in phantoms and humans when compared with a 1.5 T receive-only pelvic phased array coil, and high quality spectral resolution is demonstrated through the delineation of the citrate quadruplet in localized 1H prostate spectra. Higher fields offer the potential for MR prostate studies without the use of an endorectal coil.