Correction for heart rate variability during 3D whole heart MR coronary angiography

PURPOSE: To evaluate the effect of a real-time adaptive trigger delay on image quality to correct for heart rate variability in 3D whole-heart coronary MR angiography (MRA). MATERIALS AND METHODS: Twelve healthy adults underwent 3D whole-heart coronary MRA with and without the use of an adaptive trigger delay. The moment of minimal coronary artery motion was visually determined on a high temporal resolution MRI. Throughout the scan performed without adaptive trigger delay, trigger delay was kept constant, whereas during the scan performed with adaptive trigger delay, trigger delay was continuously updated after each RR-interval using physiological modeling. Signal-to-noise, contrast-to-noise, vessel length, vessel sharpness, and subjective image quality were compared in a blinded manner. RESULTS: Vessel sharpness improved significantly for the middle segment of the right coronary artery (RCA) with the use of the adaptive trigger delay (52.3 +/- 7.1% versus 48.9 +/- 7.9%, P = 0.026). Subjective image quality was significantly better in the middle segments of the RCA and left anterior descending artery (LAD) when the scan was performed with adaptive trigger delay compared to constant trigger delay. CONCLUSION: Our results demonstrate that the use of an adaptive trigger delay to correct for heart rate variability improves image quality mainly in the middle segments of the RCA and LAD.     

A fast 3D approach for coronary MRA.

Two-dimensional (2D)-breath-hold coronary magnetic resonance angiography (MRA) has been shown to be a fast and reliable method to depict the proximal coronary arteries. Recent developments, however, allow for free-breathing navigator gated and navigator corrected three-dimensional (3D) coronary MRA. These 3D approaches have potential for improved signal-to-noise ratio (SNR) and allow for the acquisition of adjacent thin slices without the misregistration problems known from 2D approaches. Still, a major impediment of a 3D acquisition is the increased scan time. The purpose of this study was the implementation of a free-breathing navigator gated and corrected ultra-fast 3D coronary MRA technique, which allows for scan times of less than 5 minutes. Twelve healthy adult subjects were examined in the supine position using a navigator gated and corrected ECG triggered ultra-fast 3D interleaved gradient echo planar imaging sequence (TFE-EPI). A 3D slab, consisting of 20 slices with a reconstructed slice thickness of 1.5 mm, was acquired with free-breathing. The diastolic TFE-EPI acquisition block was preceded by a T2prep pre-pulse, a diaphragmatic navigator pulse, and a fat suppression pre-pulse. With a TR of 19 ms and an effective TE of 5.4 ms, the duration of the data acquisition window duration was 38 ms. The in-plane spatial resolution was 1.0-1.3 mm*1.5-1.9 mm. In all cases, the entire left main (LM) and extensive portions of the left anterior descending (LAD) and right coronary artery (RCA) could be visualized with an average scan time for the entire 3D-volume data set of 2:57 +/- 0:51 minutes. Average contiguous vessel length visualized was 53 +/- 11 mm (range: 42 to 75 mm) for the LAD and 84 +/- 14 mm (range: 62 to 112 mm) for the RCA. Contrast-to-noise between coronary blood and myocardium was 5.0 +/- 2.3 for the LM/LAD and 8.0 +/- 2.9 for the RCA, resulting in an excellent suppression of myocardium. We present a new approach for free-breathing 3D coronary MRA, which allows for scan times superior to corresponding 2D coronary MRA approaches, and which takes advantage of the enhanced SNR of 3D acquisitions and the post-processing benefits of thin adjacent slices. The robust image quality and the short average scanning time suggest that this approach may be useful for screening the major coronary arteries or identification of anomalous coronary arteries. J. Magn. Reson. Imaging 1999;10:821-825.     

320排动态容积CT在评价冠状动脉解剖结构方面的价值

目的:探讨320排动态容积CT在评价冠状动脉解剖结构方面的价值,阐述其在CTA扫描方面的优势,并分析其对冠状动脉造影(coronary angiography,CAG)及介入治疗(percutaneous coronary intervention,PCI)的临床指导意义。方法:行320排动态容积扫描的冠状动脉CTA受检者中CTA图像未发现病变且图像质量为1级者70例,均测量其左冠状动脉主干、右冠状动脉、左前降支及左回旋支开口处的内径,左、右冠状动脉的开口位置、开口角度,左前降支与左回旋支之间角度及左主干长度,并按性别分组,行统计学分析。结果:1左冠状动脉主干、右冠状动脉、左前降支及左回旋支开口处的内径平均值分别为(4.10±0.80)mm、(3.52±0.69)mm、(3.43±0.72)mm及(2.84±0.77)mm。其中,男性平均值分别为(4.25±0.80)mm、(3.78±0.68)mm、(3.54±0.75)mm及(3.06±0.83)mm;女性平均值分别为(3.91±0.79)mm、(3.18±0.53)mm、(3.30±0.66)mm及(2.54±0.58)mm。2左、右冠状动脉起始处与升主动脉之间夹角分别为110.13°±15.04°、47.49°±17.19°。其中,男性平均值分别为108.42°±17.25°、45.57°±17.07°;女性平均值分别为112.41°±11.33°、50.05°±17.30°。左前降支与左回旋支之间夹角平均为72.70±30.88°,其中男性为74.18°±31.04°;女性为70.74°±31.08°。3左、右冠状动脉开口位置:位于窦内者分别占78.57%、81.43%,位于窦管结合处者分别占15.71%、14.29%,位于窦外者分别占5.72%、4.29%。4左主干长度平均为(10.49±4.08)mm。其中男性平均为(10.63±4.48)mm;女性平均为(10.29±3.53)mm。5冠状动脉变异情况:左、右冠状动脉开口高位者各1例;双开口10例;右冠状动脉缺如1例;心肌桥9例;冠状动脉瘘1例。结论:320排动态容积CT可清晰显示冠状动脉正常解剖结构及变异情况,对于指导CAG及PCI有重要临床意义。     

Improved three-dimensional free-breathing coronary magnetic resonance angiography using gadocoletic acid (B-22956) for intravascular contrast enhancement

PURPOSE: To evaluate gadocoletic acid (B-22956), a gadolinium-based paramagnetic blood pool agent, for contrast-enhanced coronary magnetic resonance angiography (MRA) in a Phase I clinical trial, and to compare the findings with those obtained using a standard noncontrast T2 preparation sequence. MATERIALS AND METHODS: The left coronary system was imaged in 12 healthy volunteers before B-22956 application and 5 (N = 11) and 45 (N = 7) minutes after application of 0.075 mmol/kg of body weight (BW) of B-22956. Additionally, imaging of the right coronary system was performed 23 minutes after B-22956 application (N = 6). A three-dimensional gradient echo sequence with T2 preparation (precontrast) or inversion recovery (IR) pulse (postcontrast) with real-time navigator correction was used. Assessment of the left and right coronary systems was performed qualitatively (a 4-point visual score for image quality) and quantitatively in terms of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), vessel sharpness, visible vessel length, maximal luminal diameter, and the number of visible side branches. RESULTS: Significant (P < 0.01) increases in SNR (+42%) and CNR (+86%) were noted five minutes after B-22956 application, compared to precontrast T2 preparation values. A significant increase in CNR (+40%, P < 0.05) was also noted 45 minutes postcontrast. Vessels (left anterior descending artery (LAD), left coronary circumflex (LCx), and right coronary artery (RCA)) were also significantly (P < 0.05) sharper on postcontrast images. Significant increases in vessel length were noted for the LAD (P < 0.05) and LCx and RCA (both P < 0.01), while significantly more side branches were noted for the LAD and RCA (both P < 0.05) when compared to precontrast T2 preparation values. CONCLUSION: The use of the intravascular contrast agent B-22956 substantially improves both objective and subjective parameters of image quality on high-resolution three-dimensional coronary MRA. The increase in SNR, CNR, and vessel sharpness minimizes current limitations of coronary artery visualization with high-resolution coronary MRA.     

16层螺旋CT冠状动脉血管成像技术临床应用

目的:探讨16层螺旋CT冠状动脉成像技术临床应用价值。方法:对45例临床诊断或可疑冠心病的住院患者行16层螺旋CT冠状动脉回顾性心电门控平扫及增强扫描。将增强扫描图像传送到Wizard图像工作站进行最大密度投影(MIP)、多平面重组(MPR)、曲面重组(CPR)、容积再现技术(VRT)及平带多平面重组(RMPR)。并将VRT及MIP重组像为参照,用平扫图像对冠状动脉各支段进行钙化积分。结果:左冠状动脉主干(LM)、左前降支近中段(LAD1、LAD2)、第一对角支(D1)、左回旋支(LCX)及右冠状动脉近段(RCA1)显示均45例(100%),左前降支远段(LAD3)23例(51%),第二对角支(D2)30例(67%),第三对角支(D3)24例(53%),第一左缘支(M1)36例(80%),第二缘支(M2)28例(62%),右冠状动脉中段(RCA2)41例(91%),右冠状动脉远段(RCA3)43例(96%)及后降支(PDA)34例(76%)。左冠状动脉主干钙化12例(27%),左前降支近中段钙化有29例(64%),左回旋支钙化例数22例(49%),右冠状动脉近中段钙化有24例(53%)。结论:16层螺旋CT可对冠状动脉进行钙化积分并准确显影,是冠状动脉粥样硬化疾病筛选和诊断的首选方法。     

屏气三维快速平衡稳态进动序列在磁共振冠状动脉成像中的可靠性研究

目的 :评价屏气三维快速平衡稳态进动 ( 3D FIESTA)序列在冠状动脉磁共振成像 (CMRA)中的可靠性。材料和方法 :67例受检者 ,采用心电触发的三维FIESTA序列 ,呼气末屏气采样 ,在 8个不同层面方向定位显示冠状动脉各主支 ,包括右冠 (RCA)、左主支 (LM)、左前降支 (LAD)和左回旋支 (LCX) ,以 0 -IV级图像质量体系为参照 ,评分II级以上作为可接受标准 ,采用美国心脏协会 (AHA)的冠状动脉分段标准评价其显示的长度和范围。结果 :67例受检者能够屏气配合完成检查的 65例 ,检查适用率为 97.0 % ;对AHA 18、19段 (RCA近段和中段 )、AHA 1、2 (LM)、AHA 3、5、7段 (LAD近段和中段 ) ,AHA 10段 (LCX近段 )的显示可重复性为 10 0 % ;对AHA 9、14、2 1段 (LAD、LCX和RCA的远段 )的显示可重复性分别为 95 .3 8%、72 .3 1%、96.92 %。结论 :此三维FIESTA序列可以稳定显示冠状动脉主要分支的近段和中段 ,初步具备临床应用的价值。     

磁共振冠状动脉成像定位方法

目的 摸索磁共振冠状动脉成像(MRCA)的扫描定位方法。方法 89例受检者，用快速平衡稳态成像(FIESTA)序列获得标准四腔心位、左室和右室长轴位的电影图像并确定舒张中期触发延迟时间，在此基础上用脂肪抑制的三维FIESTA序列在呼气末屏气定位扫描冠状动脉右支(RCA)、左主干(LM)、前降支(LAD)和回旋支(LCX)，以美国心脏协会(AHA)推荐的冠状动脉解剖分段法评价定位显示的可重复性。结果 86例受检者能够屏气配合完成检查，适用效率为96．63％；9个位置可以稳定地显示冠状动脉各主支，各位置综合对RCA近段和中段(AHA-18、19段)、LM全长(AHA-1、2)、LAD近段和中段(AHA-3、5、7段)，LCX近段(AHA-10段)的显示可重复性为100％；对LAD、LCX和RCA的远段(AHA-9、14、21段)的显示可重复性分别为94．19％、72．09％、96．51％。结论 MRCA定位方法简单实用，可以稳定显示冠状动脉主要分支的近段和中段，初步具备临床应用的价值。     

Volume‐targeted and whole‐heart coronary magnetic resonance angiography using an intravascular contrast agent

Purpose

To compare volume‐targeted and whole‐heart coronary magnetic resonance angiography (MRA) after the administration of an intravascular contrast agent.

Materials and Methods

Six healthy adult subjects underwent a navigator‐gated and ‐corrected (NAV) free breathing volume‐targeted cardiac‐triggered inversion recovery (IR) 3D steady‐state free precession (SSFP) coronary MRA sequence (t‐CMRA) (spatial resolution = 1 × 1 × 3 mm³) and high spatial resolution IR 3D SSFP whole‐heart coronary MRA (WH‐CMRA) (spatial resolution = 1 × 1 × 2 mm³) after the administration of an intravascular contrast agent B‐22956. Subjective and objective image quality parameters including maximal visible vessel length, vessel sharpness, and visibility of coronary side branches were evaluated for both t‐CMRA and WH‐CMRA.

Results

No significant differences (P = NS) in image quality were observed between contrast‐enhanced t‐CMRA and WH‐CMRA. However, using an intravascular contrast agent, significantly longer vessel segments were measured on WH‐CMRA vs. t‐CMRA (right coronary artery [RCA] 13.5 ± 0.7 cm vs. 12.5 ± 0.2 cm; P < 0.05; and left circumflex coronary artery [LCX] 11.9 ± 2.2 cm vs. 6.9 ± 2.4 cm; P < 0.05). Significantly more side branches (13.3 ± 1.2 vs. 8.7 ± 1.2; P < 0.05) were visible for the left anterior descending coronary artery (LAD) on WH‐CMRA vs. t‐CMRA. Scanning time and navigator efficiency were similar for both techniques (t‐CMRA: 6.05 min; 49% vs. WH‐CMRA: 5.51 min; 54%, both P = NS).

Conclusion

Both WH‐CMRA and t‐CMRA using SSFP are useful techniques for coronary MRA after the injection of an intravascular blood‐pool agent. However, the vessel conspicuity for high spatial resolution WH‐CMRA is not inferior to t‐CMRA, while visible vessel length and the number of visible smaller‐diameter vessels and side‐branches are improved. J. Magn. Reson. Imaging 2009;30:1191–1196. © 2009 Wiley‐Liss, Inc.     

256-MSCT对先天性心脏病婴儿心脏成像的冠状动脉检出情况

目的探讨256-MSCT对复杂性先天性心脏病婴儿(1岁内)心脏成像时的冠状动脉检出情况。方法从789例行256-MSCT检查的<1岁的患儿中随机抽取100例,评价冠状动脉节段的成像情况(按10个节段计算),包括检出的节段数目及血管清晰度。结果总节段检出率为51.7%,左主干(LM)及右冠状动脉(RCA)近段检出率分别为96%和99%,左前降支(LAD)、左回旋支(LCX)、RCA各支血管的节段检出率分别为53.33%、33.67%、53.33%。左、右冠状动脉近段血管清晰度评分(4分/3分/2分/1分)分别为LM(62例/22例/12例/4例)和RCA(56例/20例/17例/7例)。患儿平均接受的有效剂量为(0.898±0.282)mSv。结论 256-MSCT对复杂性先天性心脏病婴儿(1岁内)心脏成像时的冠状动脉检出情况较为满意,尤其对左、右冠状动脉近段检出率很高,且血管清晰度明显提高,能够满足临床诊断需求。     

A dual-projection respiratory self-gating technique for whole-heart coronary MRA

PURPOSE: To investigate the accuracy of a dual-projection respiratory self-gating (DP-RSG) technique in dynamic heart position measurement and its feasibility for free-breathing whole-heart coronary MR angiography (MRA). MATERIALS AND METHODS: A DP-RSG method is proposed to enable accurate direct measurement of heart position by acquiring two whole-heart projections. On 14 volunteers we quantitatively evaluated the efficacy of DP-RSG by comparison with diaphragmatic navigator (NAV) and single-projection-based respiratory self-gating (SP-RSG) methods. For DP-RSG we also compared center-of-mass and two profile-matching algorithms in deriving heart motion. Coronary imaging was conducted on eight volunteers based on retrospective gating to preliminarily validate the effectiveness of DP-RSG for whole-heart coronary MRA. Comparison of vessel delineation was performed between images reconstructed using different gating methods. RESULTS: The quantitative evaluation shows that DP-RSG more accurately tracks heart motion than NAV with all gating window (GW) values and SP-RSG approaches with GW>or=2.5 mm and profile-matching algorithms are more reliable for motion derivation than center-of-mass calculations with GW>or=1.0 mm. Whole-heart coronary MRA studies demonstrate the feasibility of using DP-RSG to improve overall delineation of the coronary arteries. CONCLUSION: DP-RSG is a promising approach to better resolve respiratory motion for whole-heart coronary MRA compared to conventional NAV and SP-RSG.     

Performance of a new gadolinium-based intravascular contrast agent in free-breathing inversion-recovery 3D coronary MRA.

In three-dimensional (3D) coronary magnetic resonance angiography (MRA), the in-flow contrast between the coronary blood and the surrounding myocardium is attenuated as compared to thin-slab two-dimensional (2D) techniques. The application of a gadolinium (Gd)-based intravascular contrast agent may provide an additional source of signal and contrast by reducing T(1blood) and supporting the visualization of more distal or branching segments of the coronary arterial tree. In six healthy adults, the left coronary artery (LCA) system was imaged pre- and postcontrast with a 0.075-mmol/kg bodyweight dose of the intravascular contrast agent B-22956. For imaging, an optimized free-breathing, navigator-gated and -corrected 3D inversion recovery (IR) sequence was used. For comparison, state-of-the-art baseline 3D coronary MRA with T(2) preparation for non-exogenous contrast enhancement was acquired. The combination of IR 3D coronary MRA, sophisticated navigator technology, and B-22956 allowed for an extensive visualization of the LCA system. Postcontrast, a significant increase in both the signal-to-noise ratio (SNR; 46%, P < 0.05) and contrast-to-noise ratio (CNR; 160%, P < 0.01) was observed, while vessel sharpness of the left anterior descending (LAD) artery and the left coronary circumflex (LCX) were improved by 20% (P < 0.05) and 18% (P < 0.05), respectively.     

Coronary anomalies assessed by whole‐heart isotropic 3D magnetic resonance imaging for cardiac morphology in congenital heart disease

Purpose

To determine the value of whole‐heart three‐dimensional magnetic resonance imaging (MRI) for coronary artery imaging in children/adolescents with congenital heart disease (CHD).

Materials and Methods

Forty children/adolescents (median age: 14 years, range 2.6–25.8) with CHD underwent free‐breathing navigator‐gated isotropic three‐dimensional steady‐state free‐precession (3D‐SSFP) MRI for cardiac morphology. Two observers independently evaluated visibility of origin, course, vessel lengths, image quality (IQ), and contrast between coronary lumen and myocardium. A subgroup was compared with cardiac catheter.

Results

The total scan time was 6.3 ± 3.2 minutes (mean ± SD, at mean heart rate 76 ± 15/min). The mean vessel length for right coronary artery (RCA) by observer 1 was 97 ± 43 mm (observer 2: 94 ± 37 mm), for left main and anterior descending artery (LM/LAD) 91 ± 40 mm (observer 2: 90 ± 40 mm), and for left circumflex artery (LCX) 64 ± 28mm (observer 2: 66 ± 28 mm). The mean vessel contrast was 0.34 ± 0.05 (range: 0.23–0.45; maximum = 1, minimum = 0). On a 4‐level score (1 = nondiagnostic, 4 = excellent), mean IQ scores ranged between 2.3–2.9 (±0.8–1.0). Both observers agreed on the presence/proximal course of RCA in 40/40, LM/LAD in 38/40, and LCX in 36/40 patients. There was complete agreement with invasive coronary angiography available in 12/40 patients (six anomalies).

Conclusion

Isotropic whole‐heart 3D‐MRI for cardiac morphology allows reliable discrimination between normal and abnormal coronary anatomy in children/adolescents with CHD. J. Magn. Reson. Imaging 2009;29:320–327. © 2009 Wiley‐Liss, Inc.     

Three-dimensional breathhold magnetization-prepared TrueFISP: a pilot study for magnetic resonance imaging of the coronary artery disease

PURPOSE: X-ray angiography is currently the standard test for the assessment of coronary artery disease. A substantial minority of patients referred for coronary angiography have no significant coronary artery disease. The purpose of this work was the evaluation of the accuracy of a three-dimensional (3D) breathhold coronary magnetic resonance angiography (MRA) technique in detecting hemodynamically significant coronary artery stenoses in a patient population with x-ray angiographic correlation. MATERIALS AND METHODS: Sequential subjects (n = 33, M/F = 22/11, average age = 57) who were referred for conventional coronary angiography were enrolled in the study. The study protocol was approved by our institutional review board. Each subject gave written informed consent. Volume-targeted 3D breathhold coronary artery scans with ECG-triggered, segmented True Fast Imaging with Steady-state Precession (TrueFISP) were acquired for the left main (LM), left anterior descending (LAD), and right coronary arteries (RCAs). Coronary MRA was evaluated with conventional angiography as the gold standard. RESULTS: The overall sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) for diagnosing any hemodynamically significant coronary artery disease (> or =50% diameter reduction) with coronary MRA was 87%, 57%, 72%, 68%, and 80%, respectively. The sensitivity of the technique in the LM, LAD, and RCA was 100%, 83%, and 100%, respectively. The NPV of the technique in the LM, LAD, and RCA was 100%, 82%, and 100%, respectively. CONCLUSIONS: Three-dimensional breathhold True Fast Imaging with Steady-state Precession is a promising technique for coronary artery imaging. It has a relatively high sensitivity and NPV. Results of this study warrant further technical improvements and clinical evaluation of the technique.     

Cardiac adrenergic innervation is affected in asymptomatic subjects with very early stage of coronary artery disease.

The aim of this study was to investigate whether, in subjects with a very early stage of coronary artery disease without hemodynamically significant coronary artery stenoses, cardiac adrenergic innervation is already affected. METHODS: Quantitative coronary angiography and dual-isotope SPECT with 123I-metaiodobenzylguanidine (MIBG) and 99mTc-sestamibi (MIBI) were conducted to assess the function of cardiac adrenergic innervation and myocardial perfusion, respectively, in 30 asymptomatic volunteers with a high familial risk for coronary artery disease. Regional quantitative analysis of MIBG uptake and washout rates was performed using the SPECT data from the anteroseptal, lateral, and inferior myocardial regions, which represented vascular supply by the left anterior descending coronary artery (LAD), left circumflex coronary artery (LCX), and right coronary artery (RCA), respectively. RESULTS: The average severity of stenoses was 33% +/- 11% in the LAD, 29% +/- 14% in the LCX, and 26% +/- 19% in the RCA. The severity of stenosis was not related to MIBI uptake in any corresponding myocardial region at rest or during exercise. However, the degree of LAD stenosis correlated directly with delayed MIBG uptake (r = 0.43; P < 0.05) and inversely with MIBG washout (r = -0.34; P = 0.06) of the anteroseptal myocardium. When subjects were divided into tertiles according to the separate severity of stenosis for each coronary artery, delayed MIBG uptake in the anteroseptal region was significantly lower in the lowest LAD tertile (0.34 +/- 0.05) than in the middle (0.41 +/- 0.06; P < 0.01) or highest (0.43 +/- 0.05; P < 0.001) LAD tertile. Correspondingly, delayed MIBG uptake in the lateral region was also lower in the lowest LCX tertile than in the middle tertile (0.34 +/- 0.04 vs. 0.41 +/- 0.06, respectively; P < 0.01). Washout rate was also higher in the lowest LAD tertile (44% +/- 7%) than in the middle (36% +/- 10%; P < 0.05) or highest LAD tertile (34% +/- 8%; P < 0.01). CONCLUSION: The degree of coronary artery stenosis was associated directly with MIBG uptake and inversely with MIBG washout. This finding suggests that the function of cardiac adrenergic nerve endings is modified even in mild coronary artery disease before denervation occurs.     

99m Tc-MIBI心肌显像对冠状动脉病变的定位研究

目的：探讨９９ｍＴｃ－ＭＩＢＩ心肌显像在检出冠心病病变心肌节段和病变血管定位上的价值。方法：对照分析２０例冠心病和５例对照组冠状动脉造影与９９ｍＴｃ－ＭＩＢＩ单光子发射断层显像（ＳＰＥＣＴ）的结果。结果：潘生丁负荷ＳＰＥＣＴ检出冠心病、病变血管和病变心肌节段的敏感性分别为９５．００％、６３．６４％和４３．６８％明显高于静息相的６０．００％、４２．４２％和２７．５９％（Ｐ＜０．０１）。与静息相比较,潘生丁负荷ＳＰＥＣＴ多发现３３．３３％的病变血管和３６．８４％的病变心肌节段。对病变血管的敏感性,ＬＡＤ高于ＲＣＡ和ＬＣＸ;对于病变心肌节段检测敏感性ＲＣＡ支配节段高于ＬＡＤ和ＬＣＸ,特异性均较高。结论：潘生丁ＳＰＥＣＴ能显著提高冠心病的检出,有效估计病变心肌范围和病变冠状动脉     

双源CT对先天性心脏病儿童冠状动脉成像效果分析

目的 分析儿童先天性心脏病双源CT(DSCT)扫描对冠状动脉显示的效果.方法 2名放射科医师分别对儿童先天性心脏病DSCT扫描的图像评分,按冠状动脉各分支成像效果评为1～4分,3分以上为成像质量较好,可以用于诊断.采用方差分析比较3个心率水平、3个年龄段下冠状动脉评分差异及4支冠状动脉分支间评分差异.采用多元线性回归分析比较各支冠状动脉评分与年龄、心率、管电压、管电流、螺距、对比剂总量、对比剂流率的关系.结果 共评价72例患儿(平均1.5岁),71.2%(205/288)的冠状动脉分支图像质量较好,可以用于诊断.左主干(3.64±0.49)分、前降支(2.97±0.40)分、右冠状动脉(2.82±0.70)分、回旋支(2.76±0.73)分,各支评分依次降低而不完全相同(F=29.00,P<0.01).<1岁组(2.80±0.65)分、≥1～3岁组(2.81±0.74)分、>3～14岁组(3.58±0.52)分,各组评分依次升高而不完全相同(F=20.16,P<0.01).心率<100次/min(bpm)组(3.54±0.56)分,100～150 bpm组(2.86±0.70)分,>150 bpm组(2.81±0.63)分,各组评分依次降低而不完全相同(F=16.72,P<0.01).多元回归分析显示年龄(r=0.013,P<0.01)和对比剂总量(r=0.292,P=0.011)与左主干评分呈正相关;年龄(r=0.509,P<0.01)、管电压与前降支评分呈正相关(r=0.292,P<0.01),心率与前降支评分呈负相关(r=-0.179,P<0.05);年龄与回旋支评分呈负相关(r=0.063,P<0.01);年龄、管电压与右冠状动脉评分呈正相关(r值分别为0.486、0.220,P值分别<0.01、<0.05).结论 DSCT能够清晰显示3岁以上或心率<100 bpm的先天性心脏病儿童的冠状动脉,限制DSCT成像效果的是患儿的基础心律和年龄.     

Combined thallium 201/technetium 99m-labeled pyrophosphate tomography for identification of the “culprit” vessel in acute myocardial infarction

Background

Many previous investigations have used the presence of transient ischemic ²⁰¹Tl perfusion defect to localize coronary artery stenosis. This study reports the results of ²⁰¹Tl tomography alone and combined ²⁰¹Tl/^99mTc-labeled pyrophosphate (^99mTc PYP) tomography employed to identify the infarct-related vessel in patients with acute myocardial infarction (AMI).

Methods and Results

All short-axis images were evaluated by dividing each left ventricular slice into eight equal sectors. In addition, for combined ²⁰¹Tl/^99mTc PYP tomography, two sectors were added to evaluate involvement of the right ventricle. In a preevaluation phase of the study, the sectors were assigned to the supplying coronary arteries in 75 patients with single chronic myocardial infarction related to the left anterior descending coronary artery (LAD), left circumflex artery (LCX), or right coronary artery (RCA). In this pilot phase, ²⁰¹Tl tomograms were reviewed in conjunction with the angiographic data. This assignment was then tested prospectively in 117 patients with AMI. As confirmed by angiography, the AMI was related to the LAC, LCX, and RCA in 54, 17, and 46 patients, respectively. Sensitivity and specificity for ^99mTc PYP accumulation on combined ²⁰¹Tl/^99mTc PYP tomography were 98% a nd 100% for the LAD, 88% and 99% for the LCX, and 98% and 96% for the RCA, respectively. For ²⁰¹Tl tomography, sensitivity and specificity for identification of the culprit vessel were 94% and 89% for the LAD, 82% and 91% for the LCX, and 72% and 96% for the RCA, respectively.

Conclusion

This prospective study demonstrates that combined ²⁰¹Tl/^99mTc PYP tomography is highly accurate for identification of the infarct-related artery in AMI, even in patients with multivessel disease. Positive contrast visualization of myocardial necrosis in both the left and right ventricle allows for reliable differentiation between AMI related to the LCX or RCA territory. In comparison, for ²⁰¹Tl tomography the sensitivity to detect the culprit vessel, particularly the LCX and RCA, appears to be lower than for ²⁰¹Tl/^99mTc PYP imaging, particularly in patients with prior infarction or right dominant coronary artery.     

3D radial sampling and 3D affine transform‐based respiratory motion correction technique for free‐breathing whole‐heart coronary MRA with 100% imaging efficiency

The navigator gating and slice tracking approach currently used for respiratory motion compensation during free‐breathing coronary magnetic resonance angiography (MRA) has low imaging efficiency (typically 30–50%), resulting in long imaging times. In this work, a novel respiratory motion correction technique with 100% scan efficiency was developed for free‐breathing whole‐heart coronary MRA. The navigator signal was used as a reference respiratory signal to segment the data into six bins. 3D projection reconstruction k‐space sampling was used for data acquisition and enabled reconstruction of low resolution images within each respiratory bin. The motion between bins was estimated by image registration with a 3D affine transform. The data from the different respiratory bins was retrospectively combined after motion correction to produce the final image. The proposed method was compared with a traditional navigator gating approach in nine healthy subjects. The proposed technique acquired whole‐heart coronary MRA with 1.0 mm³ isotropic spatial resolution in a scan time of 6.8 ± 0.9 min, compared with 16.2 ± 2.8 min for the navigator gating approach. The image quality scores, and length, diameter and sharpness of the right coronary artery (RCA), left anterior descending coronary artery (LAD), and left circumflex coronary artery (LCX) were similar for both approaches (P > 0.05 for all), but the proposed technique reduced scan time by a factor of 2.5. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Nitrate-induced coronary vasodilation by stress-magnetic resonance imaging: a novel noninvasive test of coronary vasomotion

PURPOSE: To evaluate the feasibility of assessing coronary vasodilation following exogenous nitrates, using magnetic resonance angiography (MRA). The assessment of coronary response to exogenous nitrovasodilators may have a diagnostic and prognostic impact in patients with coronary artery disease. To date, stress imaging of coronary artery vasomotion has been confined to the catheterization laboratory. MRA is emerging as a noninvasive tool for coronary artery imaging. MATERIALS AND METHODS: Coronary MRA was performed in 20 healthy volunteers (12 males, age = 33 +/- 8). We used spiral spoiled gradient echo (SSGE) sequences for imaging of coronary artery lumen. After the baseline short-axis view of the coronary artery was obtained, sublingual nitroglycerin (NTG) (0.3 mg) was administered. In all subjects, short-axis views of the coronary artery were acquired repetitively (8-10 times) from 1 up to 10 minutes after NTG administration. Measurements were obtained by two independent investigators. RESULTS: Interpretable short-axis view of left anterior descending artery (LAD) was obtained in 15 subjects (75%); in the remaining five subjects the right coronary artery (RCA) was examined. The interobserver variability was 15%, and the intraobserver variability 4%. The NTG-induced maximal vasodilation was 43 +/- 22%. The vasodilator response over time after NTG was maximal on average at 279 +/- 112 seconds, but with substantial heterogeneity. CONCLUSION: Entity and time course of nitrate-induced coronary vasodilation in the left anterior descending and/or RCA can be assessed using MRA with high feasibility and reproducibility. Coronary MRA has potential for dynamic imaging of coronary vasomotion.     

Measurement of coronary artery bifurcation angles by multidetector computed tomography

OBJECTIVE: Optimal stent deployment in coronary artery bifurcations requires information about the angle between main vessel and side branch. We evaluated the accuracy and interobserver variability of bifurcation angle measurements by contrast-enhanced 16-slice multidetector computed tomography (MDCT) in comparison with invasive angiography and examined the average angles of 4 main coronary bifurcations. METHODS: To determine the accuracy of MDCT for measurement of bifurcation angles, we scanned a coronary artery phantom containing 6 bifurcations (2-mm metal rods with angles between 25 degrees and 90 degrees ) using MDCT, and angles determined in the MDCT data set were compared with the true values. To assess interobserver variability of angle measurements in comparison to invasive angiography, the angles of 3 bifurcation sites (left anterior descending and left circumflex coronary artery [LAD/LCX], LAD and first diagonal branch [LAD/Diag 1], and posterior descending coronary artery and right posterolateral branch [PDA/Rpld]) were determined in 15 patients both in 16-detector row MDCT data sets and invasive coronary angiograms by 2 independent observers each. To assess the natural distribution of the 4 main coronary artery bifurcation angles (LAD and LCX, LAD and Diag 1, LCX and OM1, PDA and Rpld), the average angles of these bifurcations were determined in 16-slice MDCT data sets acquired for coronary artery visalization in a group of 100 consecutive patients with suspected coronary artery disease. RESULTS: The phantom study revealed a mean difference between measured and true angles of 0.7 +/- 0.5 degrees . In the comparison MDCT versus invasive angiography, the 45 angles were significantly lager in MDCT (mean: 66 +/- 20 degrees vs. 56 +/- 24 degrees , P = 0.027). Interobserver variability was significantly lower in MDCT (r = 0.91) than invasive angiography (r = 0.62). Analysis of the natural distribution of bifurcation angles by MDCT revealed average values of 80 +/- 27 degrees (LAD/LCX), 46 +/- 19 degrees (LAD/Diag1), 48 +/- 24 degrees (LCX/OM1), and 53 +/- 27 degrees (PDA/Rpld), respectively. CONCLUSION: MDCT allows assessment of coronary bifurcation angles with high accuracy, which may be of future potential for planning interventional treatment.