Global left-ventricular function assessment using dual-source multidetector CT: effect of improved temporal resolution on ventricular volume measurement

The purpose was to compare global left-ventricular (LV) function parameters measured with cine MRI with results from multiphase dual-source CT (DSCT) using 10 and 20 reconstruction phases. Twenty-eight patients with suspected or known CAD underwent DSCT coronary angiography. LV end-diastolic (EDV), end-systolic (ESV) and stroke volumes (SV), and ejection fraction (EF) were determined using LV segmentation and selection of specific phases from DSCT image sets reconstructed either at 5% or 10% steps through the R-R interval. Cine MRI served as the reference investigation. Threshold-based 3D-segmentation was feasible in all DSCT data sets. EDV and ESV were underestimated by DSCT, but showed excellent correlation (Pearson's correlation coefficient 0.95/0.97) to values obtained with MRI. Using data from 5% DSCT image reconstructions instead of 10% phase reconstructions, the position of the ED and ES phase was changed in 16 of 28 patients; ESVs were to found to be slightly smaller, whereas EDV were slightly larger, resulting in a systematic overestimation of LV EF by 1.9% (p = 0.56). Threshold-based 3D segmentation enables accurate and reliable DSCT determination of global LV function with excellent correlation to cine MRI. Minor differences in LV EF indicate that both modalities are virtually interchangeable, even if the number of reconstructed phases is limited to 10% phase reconstructions.     

电影磁共振图像评定运动员心脏形态与功能

本文对瑞典10名耐力运动员(耐力组,长跑7人,游泳3人),10名举重运动员(力量组)及10名健康无训练者(对照组)进行了心脏电影磁共振图像与最大吸氧量的测试。结果表明:1)从左室舒末容量、左室编末容量、心搏量、左室心肌重量、最大吸氧量、最大通气量等指标来看,无论是其绝对实测值,还是其按体表面积或体重校正计算的相对值,耐力组均非常显著地大于其它二组。力量组除了左室心肌重量及左室心肌重量/左室舒末容量比值略有增高外(P<0.05),其余各指标与对照组比较均无显著性差异。2)左室舒末容量、心搏量、左室心肌重量及最大通气量四指标均与最大吸氧量呈高度正相关关系,相关系数依次为0.88,0.85,0.81,0.76,各相关系数均有高度显著性(P<0.001)。3)本文各组的左室心肌重量的电影磁共振图像测定值低于以往多数类似研究对象的超声心动图测定值。文章指出,电影磁共振图像技术是评定左室心肌重量与左室容量十分准确可靠的无创性检查新方法。本文首先报道了运动员心脏电影磁共振部分指标正常测量值。     

Assessment of left ventricular function and mass in patients undergoing computed tomography (CT) coronary angiography using 64-detector-row CT: comparison to magnetic resonance imaging

PURPOSE: To quantify left ventricular function and mass derived from retrospectively ECG-gated 64-detector-row computed tomography coronary angiography data sets in comparison to cine magnetic resonance (MR) imaging as the reference standard. We hypothesized that the administration of beta-blockers prior to multidetector computed tomography (MDCT) coronary angiography has a significant impact on left ventricular functional parameters. MATERIAL AND METHODS: Multiplanar reformations in the short-axis orientation were calculated from axial contrast-enhanced CT images in 21 patients (16 male, five female; age range 41-75 years, mean 64.3+/-6.8 years) referred for CT coronary angiography. Patients whose heart rates exceeded 60 bpm received 5 mg bisoprolol orally 1 hour before the MDCT examination. In case of insufficient heart-rate reduction, up to four vials (20 mg) of metoprolol were injected intravenously. The end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), cardiac output (CO), and left ventricular mass (LVM) of the reformatted images were analyzed compared to volumetric measurements based on continuous short-axis steady-state free-precession cine MR sequences (TR 3 ms, TE 1.5 ms, FA 60 degrees ). RESULTS: On average, each patient received 15.5 mg metoprolol (range 0-20 mg) and 3.85 mg bisoprolol (range 0-5 mg). The mean heart rate was 56+/-5 bpm during CT and 73+/-9 bpm during MRI examination. This difference was statistically significant (P<0.05). Mean EDV and ESV measured on MDCT were significantly higher compared to MR (MDCT vs. MR: EDV 164.2+/-52.5 vs. 144.2+/-46.7 ml, ESV 77.3+/-46.6 vs. 63.8+/-47.3 ml; P<0.05). Mean EF and CO derived from MDCT images were significantly lower compared to MR (MDCT vs. MR: EF 55.4+/-11.8 vs. 59.3+/-15.4%, CO 4822+/-779 vs. 5755+/-1267 ml; P<0.05). Mean SV and LVM were not significantly different between both methods (MDCT vs. MR: SV 86.8+/-18.1 vs. 80.3+/-15.6 ml, P = 0.44; LVM 132.4+/-42.5 vs. 138.7+/-39.1 g, P = 0.31). CONCLUSION: Left ventricular volumes assessed by the newest-generation MDCT scanners are significantly higher compared with MRI, whereas ejection fraction and cardiac output are significantly lower in MDCT. This appears to be a result of the frequent application of beta-blockers prior to MDCT examinations.     

Quantitative assessment of ventricular function using three-dimensional SSFP magnetic resonance angiography

PURPOSE: To evaluate three-dimensional (3D), free-breathing, steady-state free precession (SSFP) magnetic resonance angiography (MRA) for volumetric assessment of ventricular function. MATERIALS AND METHODS: In 18 subjects (mean age = 21.5 years) 3D datasets of the heart and great vessels were acquired using an ECG-triggered, free-breathing SSFP technique with a T2-preparation prepulse. Data were acquired during end-systole (ES) and end-diastole (ED) for assessment of stroke volumes (SVs). Through-plane flow measurements of the great arteries were performed as well as 2D-cine SSFP imaging for comparison. For image analysis of the 3D SSFP datasets a simplex mesh model was used. Papillary muscles were excluded from ventricular volumes using thresholds. Intra- and interobserver variability (Bland-Altman analysis) and correlations (Pearson's coefficient) between volumetric and flow measurements were assessed. RESULTS: ES and ED datasets were acquired successfully in all subjects. The best correlation was observed between flow vs. 3D SSFP SV for the LV (r = 0.85, mean difference = -1.0 mL) and the RV (r = 0.89, mean difference = -2.2 mL) with high intra- (LV: r = 0.93; RV: r = 0.94) and interobserver (LV: r = 0.91; RV: r = 0.93) reproducibility. CONCLUSION: 3D SSFP datasets combined with semiautomatic segmentation algorithms allow highly accurate and reproducible assessment of left (LV) and right ventricular (RV) SVs in free-breathing subjects.     

体重指数对中国成年男性左心结构和功能影响的心血管MRI研究

目的 应用心血管磁共振(cardiovascular magnetic resonance,CMR)评价体重指数(body mass index,BMI)对中国成年男性左心结构和功能的影响.方法 选取2010年10月～2018年3月行CMR检查的男性体检者共420例,年龄30 ～50岁,按体重指数(BMI)分为三组,正...     

Stereological estimation of left-ventricular volumetric and functional parameters from multidetector-row computed tomography data

This study aims to optimize the stereological method for estimating left-ventricular (LV) parameters from retrospectively electrocardiography-gated 16-row MDCT and to compare stereological estimations with those by MRI. MDCT was performed in 17 consecutive patients with known or suspected coronary disease. Stereological measurements based on point counting were optimized by determining the appropriate distance between grid points. LV parameters were evaluated by standard CT analysis using a semi-automatic segmentation method. Two independent observers evaluated the reproducibility of the stereological method. End-diastolic volume (EDV) and end-systolic volume (ESV) estimations with a coefficient of error below 5% were obtained in a mean time of 2.3 +/- 0.5 min with a point spacing of 25 and 15 pixels, respectively. The intra- and interobserver variability for estimating LV parameters was 2.6-4.4 and 4.9-8.2%, respectively. MRI estimations were highly correlated with those by standard CT analysis (R > 0.82) and stereology (R > 0.84). Stereological method significantly overestimated EDV and ESV compared to MRI (EDV: P = 0.0011; ESV: P = 0.0013), whereas for stroke volume (SV) and ejection fraction (EF), no difference was observed (P > 0.05). For standard CT analysis and MRI, significant differences were found except for SV and EF (EDV: P = 0.0008; ESV: P = 0.0004; EF: P = 0.051; SV: P = 0.064). The time-efficient optimized stereological method enables the reproducible evaluation of LV function from MDCT.     

Feedback-assisted three-dimensional reconstruction of the left ventricle with MRI

PURPOSE: To develop and test a new technique for rapid, accurate three-dimensional (3D) reconstruction of the left ventricle (LV) and calculation of its volume parameters, with images from multiple orientations and interactive feedback. MATERIALS AND METHODS: The ventricular surface was fit to a number of user-placed guide points in magnetic resonance (MR) images using bivariate smoothing splines. A 3D model was reconstructed and the LV volumes were calculated at both end diastole (ED) and end systole (ES). This technique was validated using a phantom, and applied to studies of 18 patients and four volunteers (N = 22) imaged on a 1.5-T clinical scanner. The results of the 3D method were compared to the standard 2D short-axis slice summation technique, which is widely used for the analysis of cardiac function. RESULTS: There was excellent agreement between the computed volume of the phantom using the 3D modeling method and the actual volume (190.50 mL +/- 3.06 mL, and 191.0 mL +/- 2.5 mL, respectively). There was good correlation between the volumes calculated with our 3D model and the slice summation technique (ED volume (EDV) difference, 6.36% +/- 8.99% [mean +/- SD]; ES volume (ESV), 0.92% +/- 14.75%; stroke volume (SV), 10.54% +/- 13.95%; ejection fraction (EF), 4.22% +/- 9.16%). The 3D method was found to be more accurate than the slice summation technique for calculating LV volumes and mass from images of different slice orientations. Variations in the parameters between the two separate orientations using the 3D model vs. the slice summation method were as follows: EDV: 2.11% +/- 1.52% vs. 10.36% +/- 9.33%; ES volume: 2.76% +/- 1.64% vs. 6.39% +/- 3.62%; SV, 3.02% +/- 4.38% vs. 18.84% +/- 15.30%; EF, 2.03% +/- 2.16% vs. 8.58% +/- 6.73%; and LV mass: 4.77% +/- 2.41% vs. 24.59% +/- 6.41%. Differences in the ES volume due to the inclusion or exclusion of the most basal slice were found to be lower with the 3D model (6.90% +/- 3.83%) compared to the slice summation method (25.04% +/- 6.15%). CONCLUSION: 3D models can be used to accurately determine ventricular volume parameters. Results can be obtained using images from a variety of orientations, providing greater flexibility during image acquisition and possibly reducing the number of images needed for analysis. Feedback is provided to assist the analysis by providing a continuous update of the LV shape and volume. This feature allows the user to determine LV parameters to a predefined accuracy or to terminate the analysis when the parameters are not changing. This method is not restricted to multislice cine imaging in a single or prescribed slice orientation, and can be used for quick, accurate, and interactive analysis of cardiac function.     

Automated short-axis cardiac magnetic resonance image acquisitions: accuracy of left ventricular dimension measurements in normal subjects and patients

RATIONALE AND OBJECTIVE: This study investigates the use of an automated observer-independent planning system for short-axis cardiovascular magnetic resonance (MR) acquisitions in the clinical environment. The capacity of the automated method to produce accurate measurements of left ventricular dimensions and function was quantitatively assessed in normal subjects and patients. METHODS: Fourteen healthy volunteers and 8 patients underwent cardiovascular MR (CMR) acquisitions for ventricular function assessment. Short-axis datasets of the left ventricle (LV) were acquired in 2 ways: manually planned and generated in an automatic fashion. End-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), and left ventricular mass (LVM) were derived from the 2 datasets. The agreement between the manual and automatic planning methods was assessed. RESULTS: The mean differences between the manual and automated CMR planning methods for the normal subjects and patients were 5.89 mL and 1.93 mL (EDV), 1.14 mL and -0.41 mL (ESV), 0.81% and 0.89% (EF), and 4.35 g and 3.88 g (LVM), respectively. There was no significant difference in ESV and EF. LVM significantly differed in both groups, whereas EDV was significantly different in the normal subjects and insignificantly different in the patients. The variability coefficients were 2.8 and 3.59 (EDV), 3.3 and 5.03 (ESV), 1.79 and 2.65 (EF), and 4.36 and 2.27 (LVM) for the normal subjects and patients, respectively. The mean angular deviation of the LV axes turned out to be 8.58 +/- 5.76 degrees for the normal subjects and 8.35 +/- 5.15 degrees for the patients. CONCLUSIONS: Automated CMR planning method can provide accurate measurements of LV dimensions in normal subjects and patients, and therefore, can be used in the clinical environment for functional assessment of the human cardiovascular system.     

Gender and strain variations in left ventricular cardiac function and mass determined with magnetic resonance imaging at 7 tesla in adult mice

OBJECTIVES: We sought to assess with magnetic resonance imaging (MRI) the influence of strain type and gender on left ventricular (LV) global function and mass in 3 inbred mouse strains with a normal cardiac phenotype. MATERIALS AND METHODS: A total of 30 mice from 3 inbred strains (C57BL/6, 29S2/SvPasCrl, and C3HFeJ) were studied on a 7.05-T MR scanner using ECG-triggered cine sequences. LV mass and volumes were calculated with inclusion and exclusion of papillary muscles (PMs) in the LV wall. RESULTS: Significant differences were found with strain and gender (P < 0.001), with strain-effect but no gender-effect for ejection fraction (EF), end-diastolic volume (EDV), and end-systolic volume (ESV). There were no differences in LV mass between strains but lower values in female mice except in the C3H strain. The exclusion of PMs led to the relative underestimation of EF (-6.1%) and of LV mass (-6.4 mg) and the relative overestimation of EDV (6.3 microL) and ESV (5.3 microL). Inter- and intraobserver reproducibility was better when PMs were included. CONCLUSION: The use of MRI demonstrates cardiac interstrain and gender-related phenotypic diversities that are essential factors to consider when building genomic databases and designing studies.     

An unsupervised clustering framework for automatic segmentation of left ventricle cavity in human heart angiograms

Cardiac function is routinely assessed from X-rays angiograms acquired at the cardiac catheterization rooms. Currently, the evaluation of cardiac function involves the global measurement of volumes and ejection fraction (EF). This evaluation requires the segmentation of the left ventricle (LV) contour. Several automatic segmentation methods have been reported, however, they are not yet fully validated and accepted in the clinical work. This paper reports on an automatic segmentation method for the ventricular cavity in mono-plane and bi-plane ventriculographic image sequences. The first step is the preprocessing, where a linear regression model is applied to exploit the functional relationship between the original input image and its smoothed version. A two stage clustering algorithm is used for segmenting the left ventricle cavity. First, an approximate initial segmentation is achieved by using a simple linkage region growing algorithm on the preprocessed version of the input image. The second stage is based on a region growing method by multiple linkage. This second stage is intended for refining the initial approximate segmentation. A validation is performed by comparing the estimated contours with respect to contours traced manually by several cardiologists. The average positioning error considering 15 mono-plane and 3 bi-plane angiographic sequences is 0.72mm at end-diastole (ED) and 0.91mm at end-systole (ES). The average contour error is 6.67% at ED and 12.44% at ES. The average area error is 8.58% at ED and 3.32% at ES. The left ventricle volume and the ejection fraction are estimated from manual contours and from the estimated contours showing an excellent correlation: 0.999 for ED volume, 0.998 for ES volume, and 0.952 for EF.     

Assessment of left ventricular volumes and mass with fast 3D cine steady-state free precession k-t space broad-use linear acquisition speed-up technique (k-t BLAST)

PURPOSE: To compare left ventricular (LV) volume and mass assessment using two-dimensional (2D) cine steady-state free precession (SSFP) and k-t space broad-use linear acquisition speed-up technique (k-t BLAST) accelerated 3D magnetic resonance imaging (MRI). MATERIALS AND METHODS: On a commercially available 1.5T MR scanner, 2D cine SSFP, six- and eight-fold accelerated 3D k-t BLAST were performed to evaluate LV volumes and mass in 17 volunteers. After semiautomatic segmentation of the different MR data sets, the resulting volumes and mass were compared according to the mean difference, 95% confidence interval, standard deviation (SD), Pearson's correlation coefficient, Bland-Altman analysis, and the Pitman-Morgan test. RESULTS: Data acquisition was successful in all subjects. The number of required breathholds was reduced from a maximal of five for the 2D cine SSFP sequence to two for 3D k-t BLAST sequences. Comparing LV volumes, there was excellent agreement between 2D and 3D cine 8x k-t BLAST SSFP volumes (mean difference +/- 2SD end-diastolic volume [EDV] = 5 +/- 8 mL, end-systolic volume [ESV] = 1 +/-12 mL, and stroke volume [SV] = 3 +/- 8 mL), and mass (-1.8 +/- 9 g). CONCLUSION: k-t BLAST-accelerated 3D sequences allow accurate assessment of LV volumes and mass compared to 2D cine SSFP. This method may reduce costs and increase patient comfort due to shortened data acquisition time and reduced number of breathholds.     

Left ventricular papillary muscle mass: relationship to left ventricular mass and volumes by magnetic resonance imaging

OBJECTIVE: To evaluate the effect of papillary muscle mass on the calculation of left ventricular (LV) function and mass and to determine the relationship between papillary muscle mass with body size and sex. METHODS: Cardiac magnetic resonance imaging examinations from 50 men and 50 women were randomly selected from the Multi-Ethnic Study of Atherosclerosis database. The contours of the papillary muscles were traced manually, and the LV wall contours were outlined semiautomatically based on short-axis images. Papillary muscle mass, LV mass, and volumes were calculated. RESULTS: Inclusion of the papillary muscles results in significantly higher total LV mass values (P<0.001) and lower end-diastolic volume values (P<0.001) compared with measurements excluding papillary muscles from the LV mass. Papillary muscle mass accounts for 8.9% of the total LV mass and is correlated with LV wall mass (r=0.81, P<0.001). CONCLUSION: Papillary muscle mass significantly affects LV volumes and mass determined by cine magnetic resonance imaging.     

Quantitative analysis of cardiac left ventricular variables obtained by MRI at 3 T: a pre- and post-contrast comparison

Short-axis cine images are acquired during cardiac MRI in order to determine variables of cardiac left ventricular (LV) function such as ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and LV mass. In cardiac perfusion assessments this imaging can be performed in the temporal window between first pass perfusion and the acquisition of delayed enhancement images in order to minimise overall scanning time. The objective of this study was to compare pre- and post-contrast short-axis LV variables of 15 healthy volunteers using a two-dimensional cardiac-gated segmented cine true fast imaging with steady state precession sequence and a 3.0 T MRI unit in order to determine the possible effects of contrast agent on the calculated cardiac function variables. Image analysis was carried out using semi-automated software. The calculated mean LV mass was lower when derived from the post-contrast images, relative to those derived pre-contrast (102 vs 108.1 g, p<0.0001). Small but systematic significant differences were also found between the mean pre- and post-contrast values of EF (69.4% vs 68.7%, p<0.05), EDV (142.4 vs 143.7 ml, p<0.05) and ESV (44.2 vs 45.5 ml, p<0.005), but no significant differences in SV were identified. This study has highlighted that contrast agent delivery can influence the numerical outcome of cardiac variables calculated from MRI and this was particularly noticeable for LV mass. This may have important implications for the correct interpretation of patient data in clinical studies where post-contrast images are used to calculate LV variables, since LV normal ranges have been traditionally derived from pre-contrast data sets.     

Single-breathhold four-dimensional assessment of left ventricular volumes and function using k-t BLAST after application of extracellular contrast agent at 3 Tesla

PURPOSE: To prospectively determine the feasibility and accuracy of a four-dimensional (4D) k-space over time broad-use linear acquisition speed-up technique (k-t BLAST) for the evaluation of left ventricular (LV) volumes in comparison to standard multiple-breathhold cine imaging, using a 3.0 Tesla (3T) MR system. MATERIALS AND METHODS: In 23 subjects, short-axis cine loops completely covering the LV were acquired using conventional turbo gradient echo (GRE) imaging. Immediately after administration of gadobenate dimeglumine, a rapid single-breathhold k-t BLAST 4D dataset with the same coverage was acquired and reconstructed to short-axis views. Quantitative aortic flow measurement for LV stroke volume (LVSV) was used to calibrate both techniques. For GRE and k-t BLAST cine imaging: LV volumes, ejection fraction (EF), and blood-to-myocardium-contrast (BMC) were determined. RESULTS: k-t BLAST and GRE sequences showed a strong correlation for LV volumes and EF (r = 0.97-0.99; P < 0.001). Excellent agreement was also found between the LVSV determined by aortic flow measurements and LVSV assessed using GRE sequence and k-t BLAST sequence. BMC of GRE was similar to that of k-t BLAST cine imaging. CONCLUSION: The use of the single-breathhold 4D k-t BLAST technique for the assessment of LV volume is feasible and accurate in 3T MRI.     

Accurate automatic papillary muscle identification for quantitative left ventricle mass measurements in cardiac magnetic resonance imaging

RATIONALE AND OBJECTIVES: We sought to evaluate the automatic detection of the papillary muscle and to determine its influence on quantitative left ventricular (LV) mass assessment. MATERIALS AND METHODS: Twenty-eight Yorkshire-Landrace swine and 10 volunteers underwent cardiac magnetic resonance imaging (CMR) of the left ventricle. The variability in measurements of LV papillary muscles traced automatically and manually were compared to intra- and interobserver variabilities. CMR-derived LV mass with the papillary muscle included or excluded from LV mass measurements was compared to true mass at autopsy of the Yorkshire-Landrace swine. RESULTS: Automatic LV papillary muscle mass from all subjects correlated well with manually derived LV papillary muscle mass measurements (r = 0.84) with no significant bias between both measurements (mean difference +/- SD, 0.0 +/- 1.5 g; P = .98). The variability in results related to the contour detection method used was not statistically significant different compared to intra- and interobserver variabilities (P = .08 and P = .97, respectively). LV mass measurements including the papillary muscle showed significantly less underestimation (-10.6 +/- 7.1 g) with the lowest percentage variability (6%) compared to measurements excluding the papillary muscles (mean underestimation, -15.1 +/- 7.4 g percentage variability, 7%). CONCLUSION: The automatic algorithm for detecting the papillary muscle was accurate with variabilities comparable to intra- and interobserver variabilities. LV mass is determined most accurately when the papillary muscles are included in the LV mass measurements. Taken together, these observations warrant the inclusion of automatic contour detection of papillary muscle mass in studies that involve the determination of LV mass.     

Accuracy of different reconstruction intervals to quantify left ventricular function and mass in cardiac computed tomography examinations

PURPOSE: To compare the accuracy of cardiac dual-source CT (DSCT) reconstructions obtained at 5% and 10% of the cardiac cycle and MRI for quantifying global left ventricular (LV) function and mass in heart transplant recipients. MATERIAL AND METHODS: We prospectively included 23 heart transplant recipients (21 male, mean age 60±11.7 years) who underwent cardiac DSCT and MRI examinations. We compared LV parameters on cardiac DSCT reconstructions obtained at 5% (0%-95%) and 10% (0%-90%) intervals of the cardiac cycle and on double-oblique short-axis MR images. We determined ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and myocardial mass using commercially available semiautomated segmentation analysis software for DSCT datasets and conventional manual contour tracing for MR studies. RESULTS: Using different reconstruction intervals to quantify LV parameters at DSCT resulted in non-significant differences (P>.05). Compared to MRI, DSCT slightly overestimated LV-EDV, ESV, and mass when both 5% (11.5±25.1ml, 6.8±10.9ml, and 28.3±21.6g, respectively) and 10% (mean difference 15.3±26.3ml, 7.4±11.5ml, and 29.3±18.7g, respectively) reconstruction intervals were used. DSCT and MRI estimates of EF and SV were not significantly different. CONCLUSION: In heart transplant recipients, DSCT allows reliable quantification of LV function and mass compared with MRI, even using 10% interval reconstructions.     

Left ventricular ejection fraction and volumes calculated from dual gated SPECT myocardial imaging with 99Tcm-MIBI.

Dual gated (DG) cardiac single photon emission computed tomographic (SPECT) studies at end-diastole (ED) and end-systole (ES) were acquired in 27 ischaemic heart disease (IHD) patients after intravenous injection of 555-740 MBq 99Tcm-MIBI. Acquisition parameters were: 180 degrees from LPO to RAO, 32 projections, 64 x 64 matrix, 75 cardiac beats per projection, 80 ms at ED and 80 ms at ES for each cardiac cycle. A computer program was developed to calculate the ED and ES left ventricular (LV) volumes and LV ejection fraction (EF). The computational approach is interactive, semi-automatic and iterative with built-in visual quality control. Short axis slices are used with corresponding ED and ES slices processed as pairs from apex to base. Left ventricular cavity pixels are identified and summed on a slice-by-slice basis. Myocardial pixels are similarly identified. The computed LVEF and ED and ES volumes have been correlated with those from contrast ventriculography (CV). The mean calculated EF for 27 patients was 53.6 +/- 10.7% from DG SPECT versus 55.3 +/- 12.1% from CV (NS). The EF linear correlation coefficient was r = 0.97.     

Automatic identification of the left ventricle in cardiac cine-MR images: dual-contrast cluster analysis and scout-geometry approaches

PURPOSE: To evaluate the technical feasibility of two approaches--dual-contrast (DC) cluster analysis, and scout geometry (SG)--for automatic identification of the left ventricular (LV) cavity in short-axis (SA) cine-MR images. MATERIALS AND METHODS: The DC algorithm uses Fuzzy C-Means (FCM) cluster analysis of SA images from a black-blood double-inversion recovery turbo spin-echo (dual IR TSE) sequence, and bright-blood images from a steady-state free precession (SSFP) sequence. The SG algorithm employs geometric information from scout views (i.e., vertical long-axis (VLA) and four-chamber (4CH) views). Both algorithms incorporate additional geometric continuity constraints along with LV region segmentation to identify the LV. The performance of both algorithms was compared on images of eight healthy volunteers, and the SG algorithm was further evaluated on images of 13 clinical patients. RESULTS: The DC algorithm identified the LV in 89% (72/75 at end-diastole (ED) and 47/59 at end-systole (ES)) of the images from healthy volunteers, compared to 98% (74/75 at ED and 57/59 at ES) by the SG algorithm. Both methods are robust against interslice signal variations and misalignment. The DC method suffers from misregistration between the dual IR TSE and SSFP images near the apex at ES. The SG method identified the LV in 91% (112/122 at ED and 91/102 at ES) of the images from clinical patients. CONCLUSION: The SG method requires no additional scan, is robust and accurate, and performs better than the DC method for automatic identification of the LV.     

Comparison of left ventricular functional parameters measured by gated single photon emission tomography and by two-dimensional echocardiography

The aim of the present study was to evaluate the correlation amongst left ventricular (LV) functional parameters estimated by gated single photon emission tomography (GSPET) and two-dimensional (2D) M-mode, echocardiography (ECHOC). GSPET was performed in a single day stress/rest protocol by using either technetium-99m methoxy-isobutyl-isonitrile ((99m)Tc-MIBI) or technetium-99m tetrofosmin ((99m)Tc-myoview) in 36 consecutive patients, 21 males and 15 females; mean age 57.6+/-11.8 y, range 32-82 y. The various LV parameters studied were: ejection fraction (EF), end systolic volume (ESV), end diastolic volume (EDV), stroke volume (SV) and LV mass (LVM). The GSPET data were reconstructed using an automatic algorithm employing filtered back projection (FBP) and further analyzed by Emory cardiac (EC) toolbox versions EO-00369 and EO-00733 for the quantitative determinations of these parameters. All patients underwent ECHOC within 1-2 h of the post-stress data acquisition of GSPET. Our results showed that the LV volumes and the LVM showed good correlation (r=0.749 to 0.952, P=0.01). These values could thus be used interchangeably. The assessment of these parameters by GSPET therefore does not seem to be affected by the dose of the radioactivity administered as the dose of the (99m)Tc-labeled myocardial agents for acquiring rest study was approximately four times higher than that for the stress study. Our results also showed that the mean +/- SD values of the volumes and the EF of the LV evaluated by the two techniques, differed significantly except significant correlations for ESV, EDV and LVEF were observed between the two methods: r=0.574 to 0.954; 0.347 to 0.952 and 0.516 to 0.876 respectively. On the other hand, a wide disagreement was observed in estimating the LVM by the two techniques. The LVM measurements by 2D ECHOC were approximately double the values estimated by GSPET. Despite the large disagreement, a small correlation (r=0.33, P=0.05) was observed for LVM between the two techniques. In conclusion, although we observed a good correlation for LV volumes and LVM between the GSPET and the ECHOC techniques, yet these two techniques cannot be used interchangeably.     

Impact of papillary and trabecular muscles on quantitative analyses of cardiac function in hypertrophic cardiomyopathy

Purpose:

To examine the impact of cardiovascular magnetic resonance (CMR) partitioning methods on volumetric analysis in hypertrophic cardiomyopathy (HCM) patients. The standard CMR method for partitioning ventricular myocardium from ventricular cavity includes the myocardial papillary and trabecular muscles in the cavity volume. This approach may misrepresent ventricular mass and volume in patients with HCM due to large papillary muscles and extensive trabeculations.

Materials and Methods:

Ventricular volume and mass analyses were performed in 30 patients with HCM using the standard method and a detailed method that excluded papillary and trabecular muscles from the left ventricular (LV) volume while including them in LV mass. We also analyzed the degree of mitral regurgitation and compared the results with Doppler echocardiography in a subgroup of 12 patients. Interobserver variability was assessed.

Results:

The detailed method yielded 17% higher indexed LV mass, 20% lower indexed LV diastolic volume, 13% higher LV ejection fraction (EF) (all P < 0.0001). The resultant mitral regurgitant volumes using the detailed method had less discrepancy with Doppler echocardiography results compared with the results from the standard methods. Interobserver variability was similar by both methods.

Conclusion:

For patients with HCM, a detailed analysis in which the ventricular papillary and trabecular muscles are excluded from LV volume is preferred. J. Magn. Reson. Imaging 2009;30:1197–1202. © 2009 Wiley‐Liss, Inc.