数字化血管造影在血管成像的现状

本介绍了血管成像和介入操作中，数字化成像技术的优点，重点讨论了数字化成像在肺动脉、主动脉、周围动脉、内脏血管造影及介入技术中的应用价值。     

X线衰减校正对SPECT断层图像质量的影响

目的:评价X线衰减校正对SPECT断层图像质量的影响.材料和方法:Jaszczak模型行常规断层显像,肺癌患者1例行99mTc-octreotide SPECT显像,对衰减校正图像(AC)和非衰减校正图像(NAC)进行对比分析.结果:AC图像较NAC图像计数明显增加,尤以中心部分显著,图像更加趋于均匀;分辨率方面,NAC图像分辨率为9.5mm,AC图像分辨率为7.9mm,对比度方面两者无显著性差异(P>0.05).结论:X线衰减校正可改善图像质量.     

肝癌介入栓塞术前的能谱CT血管成像评估

目的:探讨能谱CT最佳单能量血管成像在肝癌介入栓塞术前评估的进展。方法:分析60例能谱成像增强扫描的动脉早期图像,分别行冠状位CT混合能量图像重建、最佳单能量血管重建。采用能谱分析软件处理后可产生常规混合能量(140kVp)的图像(方案A)和最佳单能量(50～70kVp)图像(方案B)。分别对两种重建图像中肿瘤周围的肝动脉分级评分,通过配对t检验的方法两种方案中的结果进行比较。结果:最佳单能量血管重建图像同混合能量血管重建图像两种方法在评价肝肿瘤动脉供血分级显示中存在显著性差异(t=28.74,P<0.001),能谱CT最佳单能量血管成像对于肿瘤的动脉血管评估优于混合能量成像。结论:能谱CT最佳单能量成像作为一种术前评估的方法,可以在不降低图像质量的前提下显著提高肝肿瘤血管的噪声比,有利于感兴趣区小血管的检出。     

Dyna-CT在非血管介入诊疗中的应用

目的 探讨与数字平板DSA结合的旋转断层重组技术所获得的CT样图像(Dyna-CT)在非血管介入诊疗过程中的应用方法及价值.资料与方法 对53例非血管病变患者行84次Dyna-CT检查.根据检查部位不同分为:骨关节21例(脊柱14例,头颅4例,肩关节2例,髋关节1例),共32次重组;软组织23例(肝脏20例,肾脏2例,盆腔1例),共37次重组.腔道9例(气管6例,食管3例),共15次重组.图像后处理主要通过多平面重组(MPR)获得Dyna-CT图像.图像的评价由介入手术医师在术中或术后进行,分为优、良、差三类.结果 在84次重组中,39次图像质量优,占46%,34次图像质量良,占41%,11次差,占13%.导致图像质量差的原因为:碘油、导管及支架造成的高密度伪影(5次),病变与周围组织密度相差太小(4次),因患者屏气不良造成移动伪影(2次).其中骨关节图像质量优20次,良10次,差2次.腔道系统图像质量优7次,良6次,差2次.软组织图像质量优12次,良18次,差7次.经统计学处理3组间差异有统计学意义.结论 通过数字平板DSA获得的Dyna-CT图像可提供清晰、任意角度的断面图像,特别在骨关节和腔道系统能获得优质的图像,可满足临床非血管介入诊疗的需要.     

INNOVA 2000血管影像系统在介入放射学中的应用及评价

目的：探讨INNOVA 2000平板式全数字化心血管影像系统在血管造影及介入治疗中的应用价值。方法：回顾性分析使用该机进行的840例血管造影及介入治疗。结果：INNOVA 2000平板式全数字化心血管影像系统能显示丰富的、无失真的、高清晰的图像。结论：该机采用全新的影像处理方法，操作方便、舒适，可以满足全身检查的需要，为临床提供充分信息。     

手动脉非增强磁共振血管成像的初步临床应用

目的 初步探讨基于血流敏感散相(FSD)和平衡稳态自由进动(SSFP)的非增强磁共振血管成像(NCE-MRA)技术在显示类风湿性关节炎患者手动脉的临床应用价值。资料与方法 22例类风湿性关节炎患者采用1.5T成像系统进行手动脉NCE-MRA和增强磁共振血管成像(CE-MRA)检查。对手动脉(划分为腕部、掌部和指部3个血管节段)的图像质量进行评分,并对图像信噪比(SNR)、对比度噪声比(CNR)和血管边缘锐利度进行测量。将NCE-MRA和CE-MRA的图像质量和测量值进行统计学比较。结果 22例患者24只手均成功完成NCE-MRA和动态CE-MRA检查。72个血管节段中,NCE-MRA有69个动脉节段的图像质量具有诊断意义,明显高于CE-MRA(96%比83%,P<0.05)。此外,NCE-MRA在手动脉各个部位的图像质量以及SNR、CNR和血管锐利度均优于CE-MRA(P<0.05)。结论 NCE-MRA能清楚地显示手动脉的各个分支,图像质量优于动态CE-MRA,对手动脉病变的诊断具有较好的临床应用潜力。     

数字化曲面断层机的临床应用

目的评价数字化曲面断层机在口腔与颌面外科疾病诊断与治疗中的用途。方法 10128例口腔与颌面外科疾病患者均经TROPHY数字全景系统摄影检查,对摄影方法与曝光条件进行了总结分析,并与传统X线胶片进行比较。结果研究证实,数字化曲面断层机摄影具有图像质量高,层次清晰,对比度好,曝光条件低,速度快,辐射剂量低等优点,并显著优于传统X线胶片。结论数字化曲面断层机是以对比度与分辨率高以及成像质量好为明显特征,在口腔临床及科研、教学方面有宽阔的应用前景。     

动态增强磁共振血管成像对主动脉疾病的诊断价值

目的的：评价动态增强磁共振血管成像对主动脉疾病的诊断价值及对临床治疗的指导作用。方法：82例怀疑有主动脉疾病的患者，应用动态增强磁共振血管成像技术扫描，并与手术结果和血管造影对照，分析DCEMRA的图像质量及其对血管的显示情况。结果：82例均获得满意图像。DCE、EMRA可清晰地显示主动脉疾病的位置以及血流动态情况。结论：动态增强磁共振血管成像是诊断主动脉疾病准确、快速、无创和首选的影像学检查方法，具有较高的临床应用价值。     

三种影像学检查对鼻咽血管纤维瘤的诊断价值分析

目的：探讨X线计算机成像（CT）、磁共振成像（MRI）及数字减影血管成像（DSA）对鼻咽血管纤维瘤的诊断价值。方法：选择经术后病理证实的鼻咽血管纤维瘤36例,分析CT、MRI及DSA的影像学表现及诊断符合率。结果：鼻咽血管纤维瘤的典型CT和MRI表现为鼻咽部软组织肿块,大部分边界清楚,密度或信号均匀,翼腭窝的扩大增宽,上颌窦后壁受压前移、塑形,但后壁骨质无破坏是其特征性表现,周围骨质的压迫塑形或吸收破坏,增强呈明显强化;CT、MRI诊断符合率分别达到94.4%和88.9%,DSA检查则可以了解病变的血供来源并可行术前超选择动脉内栓塞。结论：三种检查方法相结合,可对本病术前的定性、范围及与周围组织结构的关系等作出明确判断。     

非对比剂增强MR血管成像技术在肝动脉血管成像中的应用价值

【摘要】目的：以CTA为对照,探讨基于多反转空间标记脉冲技术的非对比剂增强MR血管成像技术（SLEEK-MRA）在肝动脉血管成像中的应用价值。方法：37例同时行CTA及SLEEK-MRA检查的临床怀疑肝脏占位患者纳入研究,CTA检查后7天内行SLEEK-MRA检查。由两位腹部影像诊断医师分别对CTA和SLEEK-MRA图像进行独立评估,评估内容包括四分法图像质量主观评价及最大显示分支级别评估。比较CTA与SLEEK-MRA在肝动脉成像图像质量及最大显示分支级别上的差异。结果：两位医师对CTA及SLEEK-MRA图像质量评分的一致性均为良好及以上（Kappa值:CTA为0.645~0.814;SLEEK-MRA为0.633~0.877）。除肝左动脉一级分支和肝右动脉一级分支外,SLEEK-MRA与CTA两种方法在肝总动脉、肝固有动脉、肝左动脉及肝右动脉血管成像图像质量评分上差异均无统计学意义（P值均>0.05）。CTA显示最大分支级别的能力优于SLEEK-MRA（P=0.020）。37例病例中,CTA显示有7例出现肝动脉变异,SLEEK-MRA显示了其中6例。结论：SLEEK-MRA作为一种无创、无辐射、无需使用对比剂的血管成像方法,在肝动脉血管成像上具有一定的应用价值。     

Imaging characteristics of an amorphous silicon flat-panel detector for digital chest radiography

PURPOSE: To evaluate the imaging characteristics of an amorphous silicon flat-panel detector (FPD) for digital chest radiography. MATERIALS AND METHODS: The 41 x 41-cm digital FPD is constructed on a single monolithic glass substrate with a structured cesium iodide scintillator layer and an amorphous silicon thin-film transistor array for image readout. Basic imaging characteristics of the FPD and associated image processing system were assessed on acquired images, including linearity, repeatability, uniformity of response, modulation transfer function (MTF), noise power spectrum, detective quantum efficiency (DQE), contrast sensitivity, and scatter content. Results with the FPD system were compared to those with a storage phosphor computed radiography (CR) system. RESULTS: Images obtained with the FPD demonstrated excellent uniformity, repeatability, and linearity, as well as MTF and DQE that were superior to those with the storage phosphor CR system. The contrast and scatter content of images acquired with the FPD were equivalent to those acquired with the storage phosphor system. CONCLUSION: The FPD provides radiographic images with excellent inherent physical image quality.     

Digital subtraction angiography system evaluation with phantoms

Advances in digital subtraction angiography imaging demonstrate the need for critical evaluation of the performance of digital subtraction equipment. The design of a phantom set for noninvasive assessment of the imaging quality of digital subtraction equipment is described; components include a remotely controlled transport system and individual patterns to evaluate the contrast and detail properties of the image intensifier, low-contrast sensitivity and resolution of the system, geometric distortion of image, linearity, mechanical and electronic stability of equipment, and effects of bone and bowel gas on iodine perception. The performance of an add-on digital radiographic system is presented, along with radiation exposure levels at the image intensifier for a range of radiographic techniques.     

Low-dose, time-resolved, contrast-enhanced 3D MR angiography in cardiac and vascular diseases: correlation to high spatial resolution 3D contrast-enhanced MRA

AIM: To evaluate the effectiveness of low-dose, contrast-enhanced, time-resolved, three-dimensional (3D) magnetic resonance (MR) angiography (TR-MRA) in the assessment of various cardiac and vascular diseases, and to compare the results with high-resolution contrast-enhanced MRA (CE-MRA). MATERIALS AND METHODS: Thirty consecutive patients underwent contrast-enhanced 3D TR-MRA and high spatial resolution 3D CE-MRA for evaluation of cardiac and thoracic vascular diseases at 1.5 T, and neurovascular, abdominal and peripheral vascular diseases at 3T. Gadolinium-based contrast medium was administered at a constant dose of 5 ml for TR-MRA, and 20 ml (lower extremity 30 ml) for CE-MRA. Two readers evaluated image quality using a four-point scale (from 0=excellent to 3=non-diagnostic), artefacts and findings on both datasets. Interobserver variability was tested with kappa coefficient. RESULTS: The overall image quality for TR-MRA was in the diagnostic range (median 0, range 0-1; k=0.74). Readers demonstrated important additional dynamic information on TR-MRA in 28 of 30 patients (k=0.84). Confident evaluation of organ perfusion (n=23), arteriovenous malformation/fistula flow patterns (n=7), exclusion of intra-cardiac shunts (n=6), and assessment of stent and conduit patency (n=5) were performed by both readers using TR-MRA. Readers demonstrated fine vascular details with higher confidence in 10 patients on CE-MRA. Using CE-MRA, Reader 1 and 2 depicted anatomical details in 6 and 5 patients, respectively, only on CE-MRA. CONCLUSION: Low-dose TR-MRA yields rapid and important functional and anatomical information in patients with cardiac and vascular diseases. Due to limited spatial resolution, TR-MRA is inferior to CE-MRA in demonstrating fine vascular details.     

Large scan field, high spatial resolution flat-panel detector based volumetric CT of the whole human skull base and for maxillofacial imaging

OBJECTIVES: To assess the feasibility of flat-panel detector based volumetric CT (fpVCT) scanning of the whole human skull base and maxillofacial region, which has thus far only been demonstrated on small, excised specimens. Flat-panel detectors offer more favourable imaging properties than image intensifiers. It is therefore likely that they will replace them in cone-beam CT scanners that are currently used to scan parts of the skull base and maxillofacial region. Furthermore, the resolution of current CT imaging limits diagnosis, surgical planning and intraoperative navigation within these regions. fpVCT might overcome these limitations because it offers higher resolution of high contrast structures than current CT. METHODS: Three embalmed cadaver heads were scanned in two scanners: an experimental fpVCT that offers a scan field large enough for a whole human head, and in a current multislice CT (MSCT). 28 structures were compared. RESULTS: Both scanners produced bone images of diagnostic quality. Small high contrast structures such as parts of the ossicular chain and thin bony laminas were better delineated in fpVCT than in MSCT. fpVCT of maxillofacial region and skull base was rated superior to MSCT (P=0.002) as found in this limited, experimental study. CONCLUSIONS: High spatial resolution fpVCT scanning of both regions in a whole human head is feasible and might be slightly superior to MSCT. fpVCT could improve diagnostic accuracy in selected cases, as well as surgical planning and intraoperative navigation accuracy.     

CR质量控制检测程序的应用

目的评价应用CR质量控制检测程序对CR系统主机性能的检测。方法通过对CR主机系统中IP背景噪声、IP的一致性、照射量指示器的校准、响应线性、激光束功能、极限分辨率和分辨率一致性、低对比度分辨率、空间距离精度、IP擦除完全性、滤线栅效应、IP通过量进行检测,对所得实验数据进行分析处理,与验收检测时的性能指标数值进行比较,判断是否符合质量控制要求。结果CR主机系统中除IP背景噪声外其他性能指标均符合质量控制技术要求。结论定期的质量控制检测的应用能有效保证系统性能良好和维持最优化的影像质量。     

Physical and technical aspects of digital mammography

The establishment of digital mammography systems constitutes a slow process, the reason for this being the general need of particular image quality in mammography. This article provides an overview of the physical basis of digital mammography with high image quality and dose as low as reasonably achievable. The trade-off of high contrast resolution and effective quantum efficiency of the imaging system on the one hand, and the demand of high spatial resolution or very small pixel size on the other hand is discussed. The actual status of the available digital detector technology for mammography is described. The digital systems presently available are superior to conventional screen-film mammographic systems with respect to contrast resolution. An outlook on possible further developments in the field of digital mammography is presented.     

A hybrid computerized fluoroscopy technique for noninvasive cardiovascular imaging.

The excellent linearity of digital image storage and retrieval permits hybrid analog-digital subtraction to extend the spatial resolution of two previously developed algorithms which employed entirely digital apparatus. A low resolution, time-integrated preinjection digital mask image is reconverted to analog form and subtracted from live analog video images of iodine administered by peripheral intravenous injection to produce a high resolution display of the cardiovascular system with contrast ten times greater than conventional fluoroscopy. Preliminary studies in dogs are compared with images obtained with our digital subtraction algorithms.     

Comparison of dynamic MRI at 3.0T and MDCT of pancreatobiliary disease: Evaluation with source,MPR, CPR,and MIP images for image quality and hepatic arterial and portal venous vessel conspicuity

Purpose

To compare contrast material‐enhanced three‐dimensional (3D) magnetic resonance imaging (MRI) at 3.0T and multidetector row computed tomography (MDCT) in the same patient with regard to image quality of pancreatobiliary disease and hepatic vascular conspicuity.

Materials and Methods

This study enrolled 32 patients with pancreatobiliary disease who underwent both gadolinium‐enhanced 3D dynamic MRI and multiphasic CT using 16‐MDCT. Data analysis of image quality was performed by two radiologists based on source images, multiplanar reconstruction (MPR), curved planar reconstruction (CPR), and maximum intensity projection (MIP) reconstruction. Determination of image quality was based on a 4‐point image quality rating scale.

Results

The overall image quality of the MRI axial images was superior to that of the axial MDCT images. The MRI protocol yielded an average score of 3.8 points versus 3.5 for the CT imaging. No significant difference was found between 3.0T MRI and MDCT images in MPR or CPR image quality. Image quality for visualization of the distal intrahepatic segmental arteries was significantly improved using MDCT imaging. No significant difference was found between the MDCT and 3.0T MR in portal vein branch image quality.

Conclusion

High‐resolution dynamic contrast‐enhanced MR imaging at 3.0T is a comprehensive technique which provides high image quality in pancreatobiliary disease. J. Magn. Reson. Imaging 2009;29:846–852. © 2009 Wiley‐Liss, Inc.     

Triple-TWIST MRA: high spatial and temporal resolution MR angiography of the entire peripheral vascular system using a time-resolved 4D MRA technique

Objectives

Multi-station contrast-enhanced magnetic resonance angiography (MRA) is considered as the imaging investigation of first choice in patients suffering from peripheral arterial occlusive disease. In order to overcome venous overlay and to gain dynamic flow information as provided by digital subtraction angiography (DSA), we developed a triple injection protocol for high-resolution MRA of the entire peripheral vascular system, applying time-resolved (TR) four-dimensional (4D) MRA sequences.

Methods

Ten patients underwent three-station TR-MRA of the pelvis and lower extremities with DSA as reference standard. Both investigations were compared concerning stenosis on a segment-by-segment basis. Furthermore, 28 consecutive patients underwent the same MR-only imaging protocol. All images were evaluated concerning image quality (1 = non-diagnostic, 4 = excellent), venous overlay (from none up to substantial) and time to venous enhancement (very early/early/normal/late).

Results

Three-station TR-MRA proved feasible and was comparable with DSA in 282 vessel segments, with underestimation grade of stenosis in four segments and overestimation in four segments, respectively. In 32/38 patients no venous overlay was noted; in six patients there was mild venous overlay. Image quality was rated excellent or good in most cases.

Conclusions

TR-MRA provides morphological and functional information without any timing issues due to optimal arterial enhancement at high spatial resolution without venous overlay.

Key Points

? Contrast-enhanced MR angiography (MRA) has become widely accepted. ? Time-resolved (TR) MRA provides dynamic arterial flow information without venous overlay. ? TR-MRA and DSA show comparable results for assessment of stenosis. ? TR-MRA provides excellent-good image quality of the peripheral vascular system.     

Optimized diagnostic angiography in high-risk patients with severe peripheral vascular disease.

Conventional arteriography remains the usual method for preoperative assessment of severe peripheral vascular disease (PVD). Unfortunately, many peripheral arteriograms are still performed with a suboptimal technique, which can cause significant diagnostic errors in patients with severe PVD. A suboptimal technique may be due to poor collimation (causing incorrect exposure and incorrect gray scale), excessive patient-film distance (magnification unsharpness), inadequate volume or density of contrast material, poor contrast resolution (screen-film arteriography), nonselective injection, patient movement, and pressure from restraints or incorrect patient position (failure to profile lesions, pseudo-occlusion from external pressure or plantar flexion). The technique of selective digital subtraction arteriography (DSA) allows one to avoid these errors. The superior contrast resolution of DSA allows use of lower concentrations of contrast material. Selective injection into the external iliac artery allows proper positioning and improves image quality. Demonstration of distal vessels is best achieved by using biplane arteriography. For patients with severe resting ischemia, especially those with diabetes, high-quality selective DSA is essential to ensure that all distal vessels suitable for distal bypass grafting are identified. When properly performed, selective DSA remains the investigation of choice for reliably demonstrating arterial anatomy in high-risk patients with severe PVD.