3.0T MR冠状动脉成像技术的初步研究

目的 探讨利用T2准备快速场回波(T2-TFE)序列进行3.0T冠状动脉MR成像(CMRA)技术的可行性.方法 采用三维T2-TFE序列在3.0T MR 成像设备上对33例研究对象进行CMRA检查,同时采用心电触发及呼吸导航回波技术,扫描获得的图像进行MIP和Soap Bubble软件重建.对图像质量进行评价并测量冠状动脉各主要分支的长度.结果 128支冠状动脉分支中达到Ⅲ级以上的有115支可以满足影像学诊断.各冠状动脉主 要分支的长度测量为LM (12.0±3.8) mm,LAD (79.4±18.9) mm,LCX (60.0±12.7) mm,RCA (110.7±27.2) mm.结论 在3.0T 设备上应用T2-TFE序列获得的冠状动脉影像具有较高SNR、CNR,图像质量基本可以满足影像学诊断需要.     

冠状动脉造影三维重建分析其分叉处病变的价值

目的以IVUS为参照,研究冠脉造影三维重建对冠状动脉分叉病变定量测量的准确性.材料和方法收集2006-09～2007-07于我院接受冠状动脉造影和血管内超声检查(WUS)的24处血管段(12例患者)的影像资料.以IVUS为参考标准,回顾性分析冠脉三维重建测量分叉病变各血管段的参数值,评估其对冠状动脉分叉病变诊断的准确性.结果12处分叉病变的主支、分支参考血管直径、分叉/开口处血管直径及面积狭窄率在冠脉三维重建和IVUS两组测量值之间无差别.以IVUS为标准,三维重建对分支开口狭窄的检出及分叉病变类型的判断各出现1例偏差.结论冠状动脉造影三维重建对冠脉分叉病变的定量测量及病变诊断具有较高的准确性.     

64排螺旋CT个性化重建方法在冠状动脉CTA的临床应用

目的 探讨64排CT不同个性化重建方法在冠状动脉成像中的应用价值.方法 收集我院2005-06-2006-06常规重建不满意而进行个性化重建后达到诊断要求的患者42例(男28例,女14例,平均年龄56.7岁);扫描采用TOSHIBA(Aquilion)64排螺旋CT( 120 kV、400 mA、0.5 mm、0.4 s/r )进行数据采集;对这些患者分别进行绝对期相和相对期相重建.结果 高心率患者好的相对期相重建平均为40%R-R间期(范围20%～60%),绝对期相平均为350 ms(范围200～600 ms).心律失常的患者相对期相重建均未达到诊断要求,绝对期相重建对图像质量有较大的改善,绝对期相平均为380 ms(范围300～420 ms).结论 绝对期相重建后的图像质量要好于相对期相重建后的图像质量;低心率患者好的重建图像质量多位于舒张中期,高心率患者好的重建图像质量多位于收缩末期和舒张早期.     

3.0 T MR自由呼吸冠状动脉成像的重建及定量分析

目的:介绍一种MR冠状动脉成像后处理重建和定量分析的方法,探讨其临床应用价值。材料和方法:采用矢量心电门控技术(VCG)和自由呼吸导航技术,对85例临床疑为冠心病的患者进行了3.0T全心冠状动脉检查,所有数据均使用Soap-Bubble进行后处理重建和定量分析,参照冠状动脉标准分段法(ACC1999)对冠脉进行分段评价,以“优”、“良”、“差”三个级别评判冠状动脉图像质量,分析测量冠脉长度、判断冠状动脉狭窄的原因及程度。结果:92%(78/85)的受检者扫描获得成功,共获得图像质量能够满足影像学评价(内径≥2mm)的冠状动脉节段385个,发现冠状动脉狭窄程度≥50%的血管共26支。图像质量优者占26例(33.3%),良者占34例(43.6%),差者占18例(23.1%)。右冠、左前降支及旋支的长度分别是(124.8±8.5)mm、(95.4±2.6)mm、(74.6±3.4)mm;直接为(2.6±0.3)mm、(2.4±0.3)mm、(2.4±0.2)mm。结论:Soap-Bubble重建能够把扭曲变形的三维冠脉映射到一个平面上,去掉和冠脉无关的干扰信息并对冠脉进行定量分析,对冠状动脉狭窄程度和原因进行初步评价。     

"Soap-Bubble" visualization and quantitative analysis of 3D coronary magnetic resonance angiograms.

In order to compare coronary magnetic resonance angiography (MRA) data obtained with different scanning methodologies, adequate visualization and presentation of the coronary MRA data need to be ensured. Furthermore, an objective quantitative comparison between images acquired with different scanning methods is desirable. To address this need, a software tool ("Soap-Bubble") that facilitates visualization and quantitative comparison of 3D volume targeted coronary MRA data was developed. In the present implementation, the user interactively specifies a curved subvolume (enclosed in the 3D coronary MRA data set) that closely encompasses the coronary arterial segments. With a 3D Delaunay triangulation and a parallel projection, this enables the simultaneous display of multiple coronary segments in one 2D representation. For objective quantitative analysis, frequently explored quantitative parameters such as signal-to-noise ratio (SNR); contrast-to-noise ratio (CNR); and vessel length, sharpness, and diameter can be assessed. The present tool supports visualization and objective, quantitative comparisons of coronary MRA data obtained with different scanning methods. The first results obtained in healthy adults and in patients with coronary artery disease are presented.     

评价导航波门控法冠状动脉MRA诊断冠状动脉狭窄的价值

目的:评价导航波门控法三维冠状动脉MRA诊断冠状动脉狭窄的价值。材料和方法:34例临床怀疑冠心病的患者用导航波门控法三维FIESTA MRA序列定向扫描冠状动脉,与DSA冠状动脉造影结果相比,评价其显示冠状动脉狭窄的价值。结果:MRA显示冠状动脉248个节段的质量平均为2.8±4.5,与DSA相比,对于>50%的冠状动脉狭窄,MRA敏感性、特异性、阳性预测值及阴性预测值分别为83.0%、98.0%、93.2%、97.5%。而对于<50%的节段性狭窄的敏感性、特异性、阳性预测值、阴性预测值分别为86.0%、96.0%、72.0%及98.8%。结论:导航波门控法三维冠状动脉成像判断>50%的冠状动脉狭窄有较高的价值,对于判断<50%的节段性冠状动脉狭窄亦有一定的价值,后者需要更多的病例证实。     

冠状动脉狭窄和粥样硬化斑块血管造影、MRA和CTA的对比研究

目的以冠状动脉血管造影(CA)为参照,比较冠状动脉MRA和CTA诊断狭窄的准确性,探讨斑块的MRA表现.材料和方法30例冠心病患者在2周内接受冠状动脉MRA、CTA和CA检查.MRA使用呼吸导航触发的高分辨三维FIESTA序列,CTA检查使用64排螺旋CT.以CA为诊断金标准,评价MRA和CTA检测≥50%狭窄血管的患者,回顾性分析冠状动脉斑块的MRA表现.结果MRA和CTA判断狭窄的敏感性、特异性和准确性分别为83.0%、86.9%、86.1%和85.1%、87.2%、86.8%.斑块的MRA复杂信号是MRA高、低估冠脉狭窄的主要原因,钙化是导致CTA高估狭窄的主要原因,MRA可以校正CTA对钙化所致狭窄的错误判断.结论高分辨三维FIESTA序列MRA显示冠状动脉狭窄的效能与CTA接近,MRA对显示钙化斑块导致的管腔狭窄比CTA有优势;斑块的MRA表现比较复杂,给狭窄的判断带来困难,也为斑块性质的判断提供机会.     

Coronary MRA with 3D undersampled projection reconstruction TrueFISP.

Undersampled projection reconstruction (PR) offers improved imaging efficiency allowing a relative tradeoff between signal-to-noise ratio (SNR) or streak artifact and the number of acquired k-space views rather than the tradeoff between resolution or aliasing artifact and the number of acquired k-space lines inherent to Fourier imaging techniques. TrueFISP (true fast imaging with steady state precession) is ideally suited for undersampled PR imaging because of its inherently high SNR. The purpose of this work was to investigate the feasibility of using undersampled three-dimensional (3D) PR TrueFISP for breathhold coronary artery imaging. Phantom studies and a preliminary in vivo comparison demonstrated the improved spatial resolution of PR over Fourier TrueFISP with the same imaging time. In a 24-heartbeat coronary imaging scheme, segmented 3D PR TrueFISP provided a 1.0 x 1.0 mm(2) isotropic in-plane voxel size while acquiring between 93 and 153 views per partition. Streak artifacts were present in some images but were not found to impede coronary artery delineation. In conclusion, 3D undersampled PR TrueFISP provides isotropic in-plane voxel size within a single breathhold and is a promising technique for coronary artery imaging.     

Coronary MRA: use in assessing anomalies of coronary artery origin

PURPOSE: The purpose of this work was to describe the use of coronary MR angiography (MRA) in the clinical evaluation of a series of patients with anomalous origin of the coronary arteries suspected on coronary angiography. METHOD: Eight patients underwent coronary MRA to further define variant coronary anatomy that was found on coronary angiography. A 2D segmented k-space gradient echo sequence was used with breath-holding. MRA images were assessed for traversal of an anomalous artery between the aorta and pulmonary artery trunks, which carries the greatest clinical significance. RESULTS: Of six patients with anomalous origin of the right coronary artery on angiography, two were shown by MRA to have an interarterial course of the anomalous vessel. Neither of two left coronary arteries with ectopic origin coursed between the great arteries, although one passed through the septum. CONCLUSION: Coronary MRA is a useful adjunctive technique to angiography in the evaluation of the relationship of anomalous coronary arteries to the great arteries.     

256层螺旋CTA对冠状动脉迂曲与冠心病相关性定量分析

目的采用256层螺旋CT血管造影(CTA)定量研究冠状动脉迂曲与冠心病发生率相关性并进一步探讨其临床价值。方法对1275例拟诊冠心病患者行冠状动脉CTA,其中男693例,女582例,年龄33～78岁,平均(57.65±12.35)岁。统计冠状动脉狭窄程度及冠状动脉迂曲发生率,分析两者间的关系,并观察其与性别的关系。结果 1275例行冠状动脉CTA患者中,冠状动脉狭窄(狭窄程度≥50%)患者336例,其中男219例(17.2%),女117例(9.2%)。冠状动脉迂曲患者441例,其中男188例(14.7%),女253例(19.8%)。冠状动脉迂曲组在不同冠状动脉狭窄程度及多支中重度狭窄时,狭窄发生率均低于无迂曲组(P值均<0.05)。结论 256层螺旋CTA可以客观显示冠状动脉的迂曲和狭窄,冠状动脉的迂曲和狭窄均引起了血流动力学的改变,两者之间具有相关性,冠状动脉迂曲可以降低冠状动脉狭窄的发生率及程度。     

Free-breathing 3D coronary MRA: the impact of "isotropic" image resolution

During conventional x-ray coronary angiography, multiple projections of the coronary arteries are acquired to define coronary anatomy precisely. Due to time constraints, coronary magnetic resonance angiography (MRA) usually provides only one or two views of the major coronary vessels. A coronary MRA approach that allowed for reconstruction of arbitrary isotropic orientations might therefore be desirable. The purpose of the study was to develop a three-dimensional (3D) coronary MRA technique with isotropic image resolution in a relatively short scanning time that allows for reconstruction of arbitrary views of the coronary arteries without constraints given by anisotropic voxel size. Eight healthy adult subjects were examined using a real-time navigator-gated and corrected free-breathing interleaved echoplanar (TFE-EPI) 3D-MRA sequence. Two 3D datasets were acquired for the left and right coronary systems in each subject, one with anisotropic (1.0 x 1.5 x 3.0 mm, 10 slices) and one with "near" isotropic (1.0 x 1.5 x 1.0 mm, 30 slices) image resolution. All other imaging parameters were maintained. In all cases, the entire left main (LM) and extensive portions of the left anterior descending (LAD) and the right coronary artery (RCA) were visualized. Objective assessment of coronary vessel sharpness was similar (41% +/- 5% vs. 42% +/- 5%; P = NS) between in-plane and through-plane views with "isotropic" voxel size but differed (32% +/- 7% vs. 23% +/- 4%; P < 0.001) with nonisotropic voxel size. In reconstructed views oriented in the through-plane direction, the vessel border was 86% more defined (P < 0.01) for isotropic compared with anisotropic images. A smaller (30%; P < 0.001) improvement was seen for in-plane reconstructions. Vessel diameter measurements were view independent (2.81 +/- 0.45 mm vs. 2.66 +/- 0.52 mm; P = NS) for isotropic, but differed (2.71 +/- 0.51 mm vs. 3.30 +/- 0.38 mm; P < 0.001) between anisotropic views. Average scanning time was 2:31 +/- 0:57 minutes for anisotropic and 7:11 +/- 3:02 minutes for isotropic image resolution (P < 0.001). We present a new approach for "near" isotropic 3D coronary artery imaging, which allows for reconstruction of arbitrary views of the coronary arteries. The good delineation of the coronary arteries in all views suggests that isotropic 3D coronary MRA might be a preferred technique for the assessment of coronary disease, although at the expense of prolonged scan times. Comparative studies with conventional x-ray angiography are needed to investigate the clinical utility of the isotropic strategy.