Measurement of right and left ventricular volumes in healthy individuals with cine MR imaging

Cine magnetic resonance (MR) imaging is a new, rapid MR pulse sequence that acquires up to 32 images per cardiac cycle at up to four levels of the heart within 4 minutes. In this study, the whole heart was encompassed by contiguous 10-mm transverse sections. Ventricular volumes were calculated by adding luminal areas determined in each section at end-diastole and end-systole. The left ventricular volume index was 57 ml/m2 +/- 9 at end-diastole and 17 ml/m2 +/- 4 at end-systole. The right ventricular volume index was 63 ml/m2 +/- 9 at end-diastole and 22 ml/m2 +/- 6 at end-systole. The left to right ventricular stroke volume ratio was 0.97 +/- 0.06, which was not statistically different from the theoretically expected ratio of 1. Interobserver and intraobserver measurements were closely correlated. Volume measurements were validated with two-dimensional echocardiography in five volunteers. Cine MR imaging allows reproducible three-dimensional measurement of right and left ventricular volumes with short imaging time and good temporal resolution.     

Determination of left ventricular volume and mass with use of biphasic spin-echo MR imaging: comparison with cine MR

In this study, the authors compared a new rapid spin-echo magnetic resonance (MR) imaging method, biphasic MR, with cine MR in the determination of left ventricular volume and mass in healthy volunteers. Biphasic spin-echo MR images covering the entire heart were obtained with use of the electrocardiogram R wave and the downslope of the T wave at both end diastole and end systole, respectively. Biphasic MR-determined values correlated well with small standard errors of the estimate (end-diastolic volume = 7.82 cm3, end-diastolic mass = 10.20 g, end-systolic mass = 10.08 g, ejection fraction = 2.62%) and were more reproducible. Cine MR-defined end-systolic volume was significantly larger (P less than .01) and ejection fraction was significantly smaller (P less than .005) than biphasic MR-determined values probably because of the uncertainty in isolating end systole with cine MR. Left ventricular volumes, mass, and ejection fraction are more accurately and reproducibly quantified in a more time-efficient manner with use of biphasic MR than with cine MR because of its significantly shorter image acquisition and reconstruction times.     

Quantification of regional myocardial function by rapid cine MR imaging

The capability of rapid (cine) MR imaging to quantitate left ventricular function was assessed in 13 normal subjects and in 15 patients with ischemic heart disease and regional wall-motion abnormalities proved by echocardiography and/or by contrast ventriculography. Fifteen to 20 MR images/cardiac cycle were acquired by using partial flip angles, short repetition times, and gradient-refocused echoes. Regional wall motion was assessed qualitatively in the equatorial left ventricular section by using the cine display and quantitatively by measuring myocardial thickness at end-diastole and at end-systole in six left ventricular segments in this plane. In normal volunteers wall motion was normal in all segments. Heterogeneity of systolic wall thickening was observed in normal subjects, ranging from 33% +/- 17% in the posteroseptal segment to 66% +/- 29% in the posterior segment. Overall systolic wall thickening was 48% +/- 28%. From the cinematic display of MR images, abnormal wall motion was observed in 40 of 90 segments in patients with ischemic heart disease, which correlated well with results of echocardiography or contrast ventriculography. Twenty-one segments were hypokinetic, 15 were akinetic, and four were dyskinetic. In patients with ischemic heart disease, percentage systolic wall thickening was 43% +/- 31% in the segments with normal wall motion, 6% +/- 18% in hypokinetic segments, -4% +/- 24% in akinetic segments, and -13% +/- 25% in dyskinetic zones. Absolute systolic wall thickening was less than 2 mm in 31 of 40 abnormal segments and was greater than 2 mm in only three. Rapid acquisition, improved temporal resolution, and the capacity for cine display make this new MR technique potentially useful not only for qualitative assessment of cardiac wall motion, but also for quantification of regional myocardial function.     

由MR成像数据计算机自动生成的前列腺体积:影像学医师利用MR成像计算体积和病理标本体积的对比

目的以病理标本作为参考标准,比较3TMR成像自动计算多功能活动形状模型(MFA)的前列腺体积(PV)与其他方法评估的前列腺体积。材料与方法本研究符合HIPAA法案,获得机构审查委员会批准,所有受试者均签署了知情同意书。91例病人(42~84岁,平均59岁)新鲜切除的     

基于双源CT数据的最小二乘曲线拟合对国人左心室功能的分析研究

目的:探讨基于双源CT容积数据的最小二乘曲线拟合法在评价左心室功能中的实现方法及其所得各指标与多次屏气电影法MR1测得的左室功能各指标的相关性及一致性.为临床提供一种能够准确计算左心室功能的方法.方法:32例纳入对象全部进行冠脉CTA及多次屏气MR心功能电影检查,在CT容积数据基础上由Matlab进行基于傅利叶变换的最小二乘多项式曲线拟合,计算拟合的左心室功能指标.对比分析拟合的心功能指标值与MR测定值之间的相关性.根据原始CT数据的时间-容积曲线形态,将32例对象分为光滑曲线组和大波动曲线组,分别将其拟合的心功能指标值与MR的对应指标进行Bland-Altman一致性分析.结果:最小二乘拟合法计算的左心室功能指标与MR的对应测量值之间具有很好的相关性(r =0.93～099,P＜0.05).Bland-Altman分析显示两组数据在95％一致性范围以外分布点数少;拟合值与MRI测量值具有良好一致性.结论:在双源CT多时相容积数据基础上应用最小二乘曲线拟合能够拟合左心室的时间-容积函数,使心功能的测量结果具有很高的准确性,对指导心功能软件的开发及临床应用具有重要价值.     

屏气电影法MRI评价左心室功能的价值

目的：探讨MR屏气电影成像技术评价左室功能的价值。方法：应用屏气电影法MRI对18例健康成年志愿者和36例心脏病患者进行检查，并对左室容量和心肌质量进行测量，将屏气电影法MRI的结果与传统电影法MRI及超声心动图进行比较。结果：（1）屏气电影法与传统电影法MRI及超声心动图所得舒张末期容量（EDV）、收缩末期容量（ESV）、射血分数（EF）相关性良好，相关系数为0．52－0．96，3种方法所测各指标的均值间比较差异无显著性意义（P＞0．05）。（2）3种方法所测舒张末期心肌质量（EDM），收缩末期心肌质量（ESM）相关系数较前3个指标低，且MRI与超声心动图所测ESM的均值差异有显著性意义（P＜0．05），MRI与超声心动图ESM测量的一致性欠佳。结论：屏气电影法MRI与传统电影法MRI、超声心动图比较，各心功能指标测量准确，相关性好，且成像时间短，无呼吸运动伪影，是1种临床实用价值很高的技术。     

MR assessment of left ventricular function: quantitative comparison of fast imaging employing steady-state acquisition (FIESTA) with fast gradient echo cine technique

PURPOSE: To evaluate the agreement of fast imaging employing steady-state acquisition (FIESTA) cine technique with segmented k-space fast gradient echo (GRE) cine technique when using them for assessment of cardiac function. MATERIALS AND METHODS: Eleven MR cine studies were performed on six healthy volunteers and five patients, using FIESTA and fast GRE techniques. The quantitative measurements of ventricular function obtained from the two techniques were compared. The data analysis was performed by two observers independently. RESULTS: Compared to fast GRE cine technique, FIESTA cine technique consistently resulted in higher end-diastolic volume (10.2%) and end-systolic volume (21.6%), but lower myocardial mass of left ventricle (19.2%) and ejection fraction (9.9%). The stroke volume obtained from the two techniques was very close. The primary explanation for this variability is that the two techniques have different mechanisms on establishing signal contrast. CONCLUSION: Compared to fast GRE technique, FIESTA provides significantly different results when using it for assessment of left ventricular function. It is important to consider this difference in the assessment of cardiac function.     

Assessment of left ventricular function by breath-hold cine MR imaging: Comparison of different steady-state free precession sequences

PURPOSE: To compare steady-state free precession (SSFP) sequence protocols with different acquisition times (TA) and temporal resolutions (tRes) due to the implementation of a view sharing technique called shared phases for the assessment of left ventricular (LV) function by breath-hold cine magnetic resonance (MR) imaging. MATERIALS AND METHODS: End-diastolic and end-systolic volumes (EDV, ESV) were measured in contiguous short-axis slices with a thickness of 8 mm acquired in 10 healthy male volunteers. The following true fast imaging with steady-state precession (TrueFISP) sequence protocols were compared: protocol A) internal standard of reference, segmented: tRes 34.5 msec, TA 18 beats per slice; protocol B) segmented, shared phases: tRes 34.1 msec, TA 10 beats per slice; and protocol C) real-time, shared phases, parallel acquisition technique: tRes 47.3 msec, TA 24 beats for 12 slices covering the entire left ventricle. RESULTS: Phase sharing leads to a significant decrease in EDV, stroke volume (SV), and ejection fraction (EF) (median difference -7.0 mL [*], -9.6 mL, and -3.4%, respectively, for protocol B; -15.3 mL, -13.3 mL, and -2.4% for protocol C; P = 0.002, *P = 0.021). The observed median difference of real-time EDV and SV estimates is of clinical relevance. Real-time cine MR imaging shows a greater variability of EDV and SV. No relevant differences in ESV were observed. CONCLUSION: The true cine frame duration of both shared phases sequence protocols exceeds the period of isovolumetric contraction (IVCT) of the left ventricle resulting in a systematic and significant underestimation of EDV and consequently SV and EF. SSFP sequence protocol parameters, particularly tRes and use of view sharing techniques, should therefore be known at follow-up examinations in order to be able to assess LV remodeling in patients with heart failure.     

Mitral or aortic regurgitation: quantification of regurgitant volumes with cine MR imaging

A new, rapid magnetic resonance (MR) imaging method, cine MR imaging, was used to determine the regurgitant fraction (RF) in patients with left-sided regurgitant lesions. Right and left ventricular stroke volumes were determined with cine MR imaging and a modified Simpson formula in ten healthy volunteers and 23 patients known to have either predominant mitral (n = 17) or aortic (n = 6) regurgitation. RFs evaluated at cine MR imaging were compared in healthy persons and patients with mild, moderate, or severe regurgitation demonstrated at angiography (n = 10) and Doppler echocardiography (n = 13). Cine MR imaging depicted regurgitant blood flow in all 29 regurgitant lesions in 23 patients as areas of low signal intensity within the regurgitant chamber. The RF was 4% +/- 7% in healthy subjects and 12% +/- 12% in those with mild, 35% +/- 14% in those with moderate, and 63% +/- 5% in those with severe regurgitation. The RFs determined by two observers were similar.     

Assessment of ventricular function with single breath-hold real-time steady-state free precession cine MR imaging

OBJECTIVE: The aim of our study was to evaluate whether a recently developed real-time steady-state free precession (trueFISP) cine sequence could be used to assess left ventricular function in a single breath-hold. CONCLUSION: Using real-time trueFISP permits one to assess left ventricular function in a single breath-hold. The dramatic reduction in data acquisition time does require some compromises. The temporal and spatial resolutions of images obtained with real-time trueFISP were considerably lower than those achieved with segmented trueFISP. Further reduction of the TR or the use of sensitivity encoding could improve temporal resolution and eliminate other limitations of real-time trueFISP.     

MR evaluation of ventricular function: true fast imaging with steady-state precession versus fast low-angle shot cine MR imaging: feasibility study

Short- and long-axis cine magnetic resonance (MR) images were obtained with a standard fast low-angle shot, or FLASH, sequence and a first-generation true fast imaging with steady-state precession (FISP) sequence on a 1.5-T MR imager. Contrast-to-noise ratios and volumetric left ventricular measurements were compared for manual and automatic segmentation. True FISP images were associated with significantly (P<.01) higher contrast-to-noise ratios and allowed better detection of the endocardial border. True FISP images were provided with short acquisition times and excellent contrast between the myocardium and the ventricular lumen.     

Quantification of left ventricular volumes from cardiac cine MRI using active contour model combined with gradient vector flow.

We investigated the feasibility of combining the active contour model with gradient vector flow (Snakes-GVF) to estimate left ventricular (LV) volumes from cardiac cine magnetic resonance imaging (MRI). MRI data were acquired from 27 patients, including 14 adults (9 men, 5 women, 55.0+/-23.3 years) and 13 children (10 boys, 3 girls, 2.7+/-2.1 years) using Gyroscan Intera (1.5 Tesla, Philips Medical Systems). LV volumes were calculated by adding the areas surrounded by the contour extracted by Snakes-GVF and compared with volumes estimated by manual tracing. Those estimated by Snakes-GVF [y (mL)] correlated well with those estimated by manual tracing [x (mL)]. In adult cases, the regression equation and correlation coefficient were y=1.008x - 0.517 and 0.996, respectively. In pediatric cases, they were y=1.174x - 2.542 and 0.992, respectively. In conclusion, Snakes-GVF is a powerful and useful tool for quantifying LV volumes using cardiac MRI.     

Quantification of left ventricular indices from SSFP cine imaging: Impact of real‐world variability in analysis methodology and utility of geometric modeling

Purpose:

To assess the impact of “real‐world” practice variation in the process of quantifying left ventricular (LV) mass, volume indices, and ejection fraction (EF) from steady‐state free precession cardiovascular magnetic resonance (CMR) images. The utility of LV geometric modeling techniques was also assessed.

Materials and Methods:

The effect of short‐axis‐ versus long‐axis‐derived LV base identification, simplified versus detailed endocardial contouring, and visual versus automated identification of end‐systole were evaluated using CMR images from 50 consecutive, prospectively recruited patients. Additionally, the performance of six geometric models was assessed. Repeated measurements were performed on 25 scans (50%) in order to assess observer variability.

Results:

Simplified endocardial contouring significantly overestimated volumes and underestimated EF (–6 ± 4%, P < 0.0005) compared to detailed contouring. A mean difference of –34g (P < 0.0005) was observed between mass measurements made using short‐axis‐ versus long‐axis‐derived LV base positioning. A technique involving long‐axis LV base identification, signal threshold‐based detailed endocardial contouring, and automated identification of end‐systole had significantly higher observer agreement. Geometric models showed poor agreement with conventional analysis and high variability.

Conclusion:

Real‐world variability in CMR image analysis leads to significant differences in LV mass, volume and EF measurements, and observer variability. Appropriate reference ranges should be applied. Use of geometric models should be discouraged. J. Magn. Reson. Imaging 2013;37:1213–1222. © 2012 Wiley Periodicals, Inc.     

Quantification of three-dimensional left ventricular segmental wall motion and volumes from gated tomographic radionuclide ventriculograms

Tomographic radionuclide ventriculograms may be used for three-dimensional wall motion analysis. We propose that automatic quantification of these images is possible, and here we describe the implementation and validation of a method to perform this task. Automatic computer methods were developed to locate the left ventricular (LV) endocardial surfaces in all time frames of the cardiac cycle. Global, regional, and local motion and volume were computed. Results were displayed using three-dimensional graphics. The methods were validated using phantom, canine, and human studies. Actual phantom values correlated well with experimentally determined volumes, y = 1.01x + 1.29ml, r = 0.99. In the canine model, the LV endocardial surfaces were located to within an average of 1.9 mm and 3.7 mm at end-diastole and end-systole, respectively. Areas of obvious wall motion abnormalities in automatically processed patient studies corresponded well with angiographically documented coronary artery disease. End-diastolic and end-systolic volumes computed automatically from single photon emission computed tomography averaged errors of 9% and 38%, respectively, when compared with contrast ventriculographic volumes. These results indicate that it is possible to automatically identify the left ventricular endocardial surface in gated tomographic radionuclide ventriculograms. The location of these surfaces corresponds well with the location of implanted endocardial markers, and global volume computed from these surfaces corresponds well with known volumes.     

Changes in left and right ventricular cardiac function after valve replacement for aortic stenosis determined by cine MR imaging

The purpose of this study was to determine the changes in function of both the left and the right ventricles (LV, RV) before and after aortic valve replacement (AVR), compared with age-matched healthy volunteers using magnetic resonance (MR) imaging. Fourteen patients with aortic stenosis underwent MR imaging (1.5 T) before and 3 (n = 14) and 12 (n = 9) months after surgical valve replacement. An electrocardiographically triggered two-dimensional cine fast low-angle shot sequence was used for the evaluation of absolute values and indices related to 1 m(2) body surface area for function, mass, and LV wall thickening. Fourteen age-matched healthy volunteers served as controls. Before surgery, all patients showed significant abnormalities of LV mass and function, whereas RV mass and function were not different from those of volunteers and remained mostly unchanged. After surgery, normalization of LV ejection fraction, absolute mass, and end-systolic wall thickness was observed, whereas the LV mass index failed to normalize, and LV volumes remained elevated. Aortic stenosis combined with a significant, but not severe reduction in LV function only affects the LV, whereas the RV remains unaffected at this stage of disease. AVR leads to improved LV function and reduced hypertrophy, but without normalization of LV volumes or the LV mass index within 1 year.