Calculation Of Left Ventricular Volume Research Articles

Comparison of totally automated and manual processing for calculation of left ventricular volumes and ejection fraction using gated myocardial perfusion SPECT

ated single-photon emission computed tomography (SPECT) allows for the assessment of myocardial left ventricular ejection fraction and left ventricular volumes. There is conflicting data regarding the difference between automated and manual processing of gated myocardial SPECT images. The purpose of this retrospective “cross-sectional study is to compare the degree of variability between automated and manual processing of Quantitative Gated SPECT algorithms for assessing left ventricular volumes and ejection percent”. Study was carried out in the Nuclear Medicine department “at the Security Forces Hospital, Riyadh, Saudi Arabia, and comprised of 96 participants who “underwent” both stress and “rest gated” myocardial perfusion “imaging” (MPI) from February to May 2021. Data were analyzed “using SPSS for Windows (version 22; IBM Corp., Armonk, NY, USA). The mean of EF, ESV, and EDV on stress test using the automatic technique were 62.46 ± 14.62%, 45.00 ± 37.10 ml, and 107.01 ± 43.70 ml, respectively while using the manual technique were 57.21±14.80%, 44.35±35.93 ml, and 93.26±39.14 ml, respectively. The mean of EF, ESV, and EDV on rest test using the automatic technique were 62.85± 15.47%, 43.44± 36.35 ml, and 104.27±42.51 ml, respectively while using the manual technique were 57.74±15.33%, 43.30±36.42 ml, and 91.72±41.50 ml, respectively. For LVEF and EDV, the difference between automated and manual techniques is statistically significant (p<0.05). However, no “statistically significant difference” exists between automated and manual ESV techniques (p>0.05). Discrepancies were observed that exist by using the fully automated and manual technique for determining LVEF and Left ventricular volumes by gated MPI.

Calculation of left ventricular volumes and systolic indices in monitoring the therapeutic effect of levothyroxine replacement therapy in subclinical hypothyroidism.

Subclinical hypothyroidism (SCH) is defined as high thyroid-stimulating hormone (TSH) and normal thyroxine (T4) levels. Data on the effects of early substitution with levothyroxine on psychophysical health in SCH are not consistent enough to support its general administration. The aim of this study was to examine the effect of 3-months levothyroxine (LT4) treatment on cardiovascular function in symptomatic SCH with TSH <10mIU/L. Anthropometric, biochemical, electro- and echocardiographic indices were measured in 35 patients with persistent symptomatic SCH (4mIU/L < TSH <10mIU/L; mean±SD: 7.0±2.1mIU/L) and 40healthy controls at baseline and three months after the euthyroid state had been achieved on LT4 for SCH group, or 3months of follow-up for controls. The analyses showed a significant reduction in body weight (P=.030), systolic and diastolic blood pressure (P=.024, P=.019), TSH (P<.001) and thyroid peroxidase antibodies (TPOAb) (P<.001) on LT4 in the SCH group. There was a statistically significant decrease in end-systolic (ESV) and end-diastolic volumes (EDV) (P<.001, P<.001, respectively) after LT4 treatment. LT4 therapy significantly increased values of ejection fraction (EF), global longitudinal, circumferential and radial strains (P<.001, P<.001, P<.001, respectively). Our study confirmed an echocardiographic improvement of cardiac structure and function in treated individuals. Findings suggest the role of electrocardiographic and echocardiographic examination in objective monitoring for LT4 therapeutic effects.

Automatic calculation of left ventricular volume in magnetic resonance imaging using an image-based clustering approach

In this work we propose an algorithm to automate the process of left ventricular (LV) volume calculation during magnetic resonance imaging (MRI) analysis. The proposed algorithm does the LV segmentation, volume calculation, finds the time frames where the heart is in systole and diastole phase, and calculates LV ejection fraction. The proposed approach has been tested on a dataset containing MRI study results of 500 patients. According to experimental results the root mean square error of LV systolic volume calculation is 21.64 ml, LV diastolic volume - 44.92 ml, ejection fraction - 7.96 %.

Calculation of left ventricular volumes and ejection fraction from dynamic cardiac-gated 15O-water PET/CT: 5D-PET

BackgroundQuantitative measurement of myocardial blood flow (MBF) is of increasing interest in the clinical assessment of patients with suspected coronary artery disease (CAD). 15O-water positron emission tomography (PET) is considered the gold standard for non-invasive MBF measurements. However, calculation of left ventricular (LV) volumes and ejection fraction (EF) is not possible from standard 15O-water uptake images. The purpose of the present work was to investigate the possibility of calculating LV volumes and LVEF from cardiac-gated parametric blood volume (VB) 15O-water images and from first pass (FP) images.Sixteen patients with mitral or aortic regurgitation underwent an eight-gate dynamic cardiac-gated 15O-water PET/CT scan and cardiac MRI. VB and FP images were generated for each gate. Calculations of end-systolic volume (ESV), end-diastolic volume (EDV), stroke volume (SV) and LVEF were performed with automatic segmentation of VB and FP images, using commercially available software. LV volumes and LVEF were calculated with surface-, count-, and volume-based methods, and the results were compared with gold standard MRI.ResultsUsing VB images, high correlations between PET and MRI ESV (r = 0.89, p < 0.001), EDV (r = 0.85, p < 0.001), SV (r = 0.74, p = 0.006) and LVEF (r = 0.72, p = 0.008) were found for the volume-based method. Correlations for FP images were slightly, but not significantly, lower than those for VB images when compared to MRI. Surface- and count-based methods showed no significant difference compared with the volume-based correlations with MRI. The volume-based method showed the best agreement with MRI with no significant difference on average for EDV and LVEF but with an overestimation of values for ESV (14%, p = 0.005) and SV (18%, p = 0.004) when using VB images. Using FP images, none of the parameters showed a significant difference from MRI. Inter-operator repeatability was excellent for all parameters (ICC > 0.86, p < 0.001).ConclusionCalculation of LV volumes and LVEF from dynamic 15O-water PET is feasible and shows good correlation with MRI. However, the analysis method is laborious, and future work is needed for more automation to make the method more easily applicable in a clinical setting.

Apical rotation in patients with ST-elevation myocardial infarction

Objective: The aim of this study was to assess apical rotation in patients with anterior and inferior myocardial infarction (MI) by speckle-tracking echocardiography. Background: Left ventricular ejection fraction (LVEF) is the most widely used index of left ventricular (LV) systolic function. However, the development of wall-motion abnormalities after acute MI significantly decreases the accuracy of LVEF; further, calculation of LV volume by the biplane Simpson method is inaccurate, because it depends on geometric assumptions. Recently, two-dimensional speckle-tracking imaging has facilitated noninvasive measurement of LV strain and rotation. Patients and methods: The present study enrolled 54 patients with anterior or inferior MI, in addition to 20 healthy volunteers (matched for age and sex) as the control group. Basal and apical LV short-axis images were acquired for further off-line analysis. Using commercially available two-dimensional strain software, apical, basal rotation, and LV torsion were calculated. Results: Apical rotation was significantly reduced in the patient group compared with the control group (P Conclusion: There was a significant correlation between ejection fraction and apex rotation (r = 0.466, P = 0.044), torsion degree (r = 0.499, P = 0.03), and untwisting rate (r = −0.543, P Correlation with basal rotation was nonsignificant, and thus measurement of apical rotation alone (rather than calculation of LV torsion) might provide a simple and accurate alternative for assessment of LV contractility. No difference was found between anterior and inferior MI as regards torsion (P = 0.870). Apical rotation and torsion were decreased in ST-elevation MI, and this was statistically significant in patients with LV dysfunction.

Intraoperative Evaluation of Left Ventricular Volume and Function

Intraoperative Evaluation of Left Ventricular Volume and Function

Quantification of left ventricular volumes, mass, and ejection fraction using cine displacement encoding with stimulated echoes (DENSE) MRI.

To test the hypothesis that magnitude images from cine displacement encoding with stimulated echoes (DENSE) magnetic resonance imaging (MRI) can accurately quantify left ventricular (LV) volumes, mass, and ejection fraction (EF). Thirteen mice (C57BL/6J) were imaged using a 7T ClinScan MRI. A short-axis stack of cine T2-weighted black blood (BB) images was acquired for calculation of LV volumes, mass, and EF using the gold standard sum-of-slices methodology. DENSE images were acquired during the same imaging session in three short-axis (basal, mid, apical) and two long-axis orientations. A custom surface fitting algorithm was applied to epicardial and endocardial borders from the DENSE magnitude images to calculate volumes, mass, and EF. Agreement between the DENSE-derived measures and BB-derived measures was assessed via coefficient of variation (CoV). 3D surface reconstruction was completed on the order of seconds from segmented images, and required fewer slices to be segmented. Volumes, mass, and EF from DENSE-derived surfaces matched well with BB data (CoVs ≤11%). LV mass, volumes, and EF in mice can be quantified through sparse (five slices) sampling with DENSE. This consolidation significantly reduces the time required to assess both mass/volume-based measures of cardiac function and advanced cardiac mechanics.

Functional analysis by 64-slice CT scanning: prediction of left ventricular dysfunction together with reduction in radiation exposure?

Functional analysis by 64-slice CT scanning: prediction of left ventricular dysfunction together with reduction in radiation exposure?

Real Time Triplane Echocardiography in Aortic Valve Stenosis: Validation, Reliability, and Feasibility of a New Method for Valve Area Quantification

The aim of the study was to validate a novel formula for aortic valve area (AVA) based on the principle of continuity equation, that substitutes Doppler-derived stroke volume (SV) by SV directly measured with real time simultaneous triplane three-dimensional echocardiography (RT3P). RT3P has proved accuracy for left ventricular volume calculation. So far, however, neither this potential has been applied to hemodynamic assessment, nor RT3P has succeeded in the evaluation of aortic valve disease. AVA was measured in 21 patients with aortic stenosis using Gorlin's equation, Doppler continuity equation (two-dimensional echocardiography), the novel RT3P method, and by substituting Doppler-derived SV by SV measured with two-dimensional stroke volume (2DSV). RT3P has the best linear association (R(2)= 0.61) and the best correlation with Gorlin of all noninvasive methods (even if not statistically significant). RT3P carries significantly lower mean differences with catheterization, as compared with 2D and 2DSV (Table 4). Standard deviations of mean differences between RT3P and catheterization and between the other echocardiographic methods are not statistically different, even if RT3P seems to be nearer to catheterization. Inter- and intraobserver variability were, respectively, 0.03 +/- 0.11 cm(2) and 0.02 +/- 0.03 cm(2), better than 2D and 2DSV. RT3P has revealed to be more accurate than two-dimensional method in AVA quantification, with a better intraobserver agreement. In addition, it allows simple and fast image acquisition.

Calculation of left ventricular volume based on GVF model and optical flow field

Concerning the problems of difficult segmentation and large computation in calculating the Left Ventricular (LV) volume using tagged cardiac magnetic resonance image,a new method of calculating the LV volume was proposed. First an advanced snake model based on the gradient vector field (GVF-snake) was used to segment the contour of the left ventricular and an initial snake line of the contour was got,then optical flow method was used to track the contour of the LV in the successive images. Finally,the Simpson method was applied to calculate the volume of the LV. The comparison of the result by this method with the result got manually shows that the combination of the GVF-snake model and optical flow method is feasible to calculate the volume of the LV.

Left ventricular volume assessment by planar radionuclide ventriculography evaluated by MRI

Assessment of left ventricular (LV) ejection fraction (LVEF) and LV volume are essential for the evaluation of prognosis in cardiac disease. LVEF and LV volumes can be measured with several imaging modalities, such as magnetic resonance imaging (MRI) or computed tomography; however, these are relatively expensive and time consuming. In contrast, planar radionuclide ventriculography (PRV) for LVEF assessment is a cost-effective, fast, and reliable technique, but PRV for LV volumes calculation is less common. Evaluation of a new hybrid geometrical count-based method (HGCBM) in comparison with two count-based methods (CBMs) and a geometrical method (GM) for the calculation of LV volumes with PRV using MRI as reference. Thirty cardiac patients underwent routine PRV with a standard dose of 500 MBq of Tc-pertechnetate and additional cardiac MRI as reference method. LV volumes of PRV data were calculated by four different methods. The CBMs and GM are based on the assumption that the shape of the LV can be approximated by an ellipsoid or sphere, and the new HGCBM extracts the volume from the projected count rates themselves. All methods underestimated the LV volumes as compared with the MRI-measured volumes. The difference (mean+/-SD) of end-diastolic volume (EDV) between PRV and MRI was 33+/-23 ml for GM, 12+/-26 ml for HGCBM, 50+/-38 ml for CBM1, and 13+/-40 ml for CBM2. The correlation coefficients for EDV between PRV methods and MRI were r = 0.90 for GM and r = 0.85 for HGCBM. The CBMs showed poor correlation r = 0.64 with the MRI data and a high SD. The difference of end-systolic volume (ESV) between PRV and MRI was 23+/-19 ml for GM, 9+/-22 ml for HGCBM, 29+/-29 ml for CBM1, and 9+/-28 ml for CBM2. The correlation coefficients for ESV between PRV methods and MRI were r = 0.955 for GM and r = 0.914 for HGCBM, r = 0.85 for CBM1 and CBM2. Although GM showed a slightly higher correlation than HGCBM, the difference of EDV and ESV between PRV and MRI was much higher for GM in comparison with HGCBM. Both CBMs showed poor agreement with MRI data. PRV using the new HGCMB method in comparison with other methods is an easy and accurate method to determine LV volumes. However, all methods underestimate ESV and EDV slightly as compared with MRI.

Real-Time 3-Dimensional Echocardiography

One of the most significant developments of the last decade in ultrasound imaging of the heart was the evolution of 3-dimensional (3D) imaging from slow and labor-intense offline reconstruction to real-time volumetric imaging. This imaging modality provides valuable clinical information that empowers echocardiographers with new levels of confidence in the diagnosis of heart disease. We have previously described the technological milestones in the development of real-time 3D echocardiographic (RT3DE) imaging and its major advantages over conventional 2-dimensional echocardiography (2DE) and reviewed the published literature that supported the use of this new methodology in clinical practice.1 Since 2006, the growing availability of RT3DE technology, its ease of use, and its multiple attractive features have sparked significant interest in the research community, resulting in a large number of publications, most of which have endorsed RT3DE imaging for clinical use by demonstrating its unique capabilities in different scenarios. In parallel, the clinical acceptance of this new tool has broadened significantly. The most recent clinically significant addition is matrix-array transesophageal echocardiography (TEE), which provides images of unprecedented quality that aid surgeons and interventional cardiologists in planning and guiding procedures and evaluating their outcomes. The purpose of the present article is to review the most recent RT3DE literature and provide readers with an update on the latest developments and the current status of this noninvasive imaging tool. Because different potential applications of RT3DE imaging have been explored to various extents, they are described here separately, and each is discussed with an emphasis on the scientifically established facts, along with the known stumbling blocks and difficulties. A firmly established advantage of 3D imaging over cross-sectional slices of the heart is the improvement in the accuracy of the evaluation of left ventricular (LV) volumes and ejection fraction (EF) by eliminating the need for geometric modeling, which …

Left ventricular volume measurement with echocardiography: a comparison of left ventricular opacification, three-dimensional echocardiography, or both with magnetic resonance imaging

Both contrast enhanced (CE) two-dimensional echocardiography (2DE) and three-dimensional echocardiography (3DE) have been proposed as techniques to improve the accuracy of left ventricular (LV) volume measurements. We sought to examine the accuracy of non-contrast (NC) and CE-2DE and 3DE for calculation of LV volumes and ejection fraction (EF), relative to cardiac magnetic resonance imaging (MRI). We studied 50 patients (46 men, age 63 +/- 10 year) with past myocardial infarction who underwent echocardiographic assessment of LV volume and function. All patients sequentially underwent NC-2DE followed by NC-3DE. CE-2DE and CE-3DE were acquired during contrast infusion. Resting echocardiographic image quality was evaluated on the basis of NC-2DE. The mean LV end-diastolic volume (LVEDV) of the group by MRI was 207 +/- 79 mL and was underestimated by 2DE (125 +/- 54 mL, P = 0.005), and less by CE-2DE (172 +/- 58 mL, P = 0.02) or 3DE (177 +/- 64 mL, P = 0.08), but EDV was comparable by CE-3DE (196 +/- 69 mL, P = 0.16). Limits of agreement with MRI were similar for NC-3DE and CE-2DE, with the best results for CE-3D. Results were similar for calculation of LVESV. Patients were categorized into groups of EF (< or =35, 35-50, >50%) by MRI. NC-2DE demonstrated a 68% agreement (kappa 0.45, P = 0.001), CE-2DE a 62% agreement (kappa 0.20, P = 136), NC-3DE a 74% agreement (kappa 0.39, P = 0.005) and CE-3DE an 80% agreement (kappa 0.56, P < 0.001). CE-2DE is analogous to NC-3DE in accurate categorization of LV function. However, CE-3DE is feasible and superior to other NC- and CE-techniques in patients with previous infarction.

Real-time three-dimensional echocardiography in aortic stenosis: a novel, simple, and reliable method to improve accuracy in area calculation

The aim of the study was to validate a novel formula for aortic area, based on the principle of continuity equation (CE), that substitutes Doppler-derived stroke volume (SV) by SV directly measured with real-time three-dimensional (RT3D) echo and semi-automated border detection. RT3D has proved outstanding accuracy for left ventricular volume calculation. So far, however, neither this potential has been applied to haemodynamic assessment, nor RT3D has succeeded in the evaluation of aortic valve disease. Aortic area was measured in 41 patients with aortic stenosis using Gorlin's equation, Hakki's formula, Doppler CE, two-dimensional Simpson's volumetric method, and by the novel RT3D method. RT3D has the best linear association and absolute agreement with Gorlin of all non-invasive methods r = 0.902, intraclass correlation coefficient (ICC) = 0.846, better than CE (r = 0.646, ICC = 0.626) and two-dimensional volumetric method (r = 0.627, ICC = 0.378). Linear and Passing-Bablok regression show that RT3D fits better to Gorlin (r(2) = 0.814) than CE (r(2) = 0.417) and two-dimensional method (r(2) = 0.393). Its accuracy is comparable to Hakki's formula, routinely employed in catheter laboratories. Inter- and intraobserver agreements (ICC) were, respectively, 0.732 and 0.985, better than CE (0.662, 0.857). RT3D also grades most efficiently the severity of aortic stenosis as mild, moderate, or severe (weighted kappa = 0.932). RT3D underestimates aortic area (95% CI 0.084-0.193). ROC curves, however, show that the optimal cutoff point to consider aortic stenosis severity remains close to 1 cm(2) (1.06 cm(2)). RT3D is more accurate than CE and than two-dimensional volumetric methods to calculate area and to grade the severity of aortic stenosis. Area obtained by three-dimensional echo is slightly underestimated, but its range is clinically negligible.

Cardiac changes after SCUBA diving: the evasive shape of right ventricle

We have read with interest the paper by Obad et al. (2007), ‘The effects of acute oral antioxidants on diving-induced alterations in human cardiovascular function’, recently published in The Journal of Physiology. We were somewhat puzzled by the method used to calculate right ventricular volumes. As is known, radionuclide angiography is still considered the most reliable method for evaluating right ventricular volumes and function. Previous attempts of obtaining a two-dimensional echocardiographic estimate of right heart volumes were based on multiple cardiac views and complex mathematical formulas (Starling et al. 1982) and, more recently (Pasipoularides et al. 2003), a 3-D echo approach has been successfully applied. Contrary to this, Simpson's method, already validated for the calculation of left ventricular volumes, does not seem applicable to a cavity with such a complex three-dimensional geometry like the right ventricle. The scarce reliability of the method used in the paper by Obad et al. (2007) appears evident if one considers the large difference between left and right ventricular stroke volumes evinced in Table 3 (93.1 ml for left ventricle versus about 37 ml for right ventricle, simply considering mean values of right ventricular diastolic and systolic volumes). Even if the paper contains a number of interesting new data on the physiology of diving, we think that anatomical and functional characterization of right heart requires a more reliable methodological approach.

8.62

8.62

A Comparison of Myocardial Perfusion Gated SPECT Studies Obtained at Rest and after Stress

Objective: To perform a comparison between post-stress and rest gated single-photon emission computer tomography (SPECT) myocardial perfusion imaging (MPI) studies to assess post-stress stunning and the variables underlying this phenomenon. Subjects and Methods: This was a prospective study of 318 consecutive adult patients undergoing stress and rest gated SPECT using a 2-day ^99mTc-tetrofosmin protocol. Bruce protocol treadmill stress (n = 93) or i.v. dipyridamole pharmacologic stress (n = 225) were used as stressors. Ejection fractions (EF) and left ventricular (LV) end-diastolic (EDV) and end-systolic volumes (ESV) were calculated using the Cedars Sinai Quantitative Gated SPECT software. Perfusion defects were visually scored using a 20-segment model to obtain summed stress scores. Statistical analysis was performed by applying paired t test and multi-regression. Statistically significant (p < 0.05) paired differences between post-stress and rest EF and ESV and type of stressing were noted. Results: Analysis of patient groups based on the type of stress showed significantly low EF on post-stress studies for both treadmill and dipyridamole stressing and also significantly high ESV on post-stress studies for dipyridamole. Multi-regression analysis using differences in post-stress and rest EF, EDV and ESV as dependent and summed stress scores, type of stress, delay time, previous myocardial infarction and size of LV as independent variables showed statistically significant associations between high summed stress scores (>13) and size of post-stress LV for EDV and ESV differences. High volumes were noted on post-stress studies. The magnitudes of the observed differences were well within the reproducibility of LV volume calculations. Conclusions: Patients showing stunning had significant ischemia or a dilated LV. The stunning manifested as high EDV and ESV differences. The magnitude of the differences observed in EF and LV volumes were not clinically significant.

Automated vs. manual assessment of left ventricular function in cardiac multidetector row computed tomography: comparison with magnetic resonance imaging

We compared semiautomatic contour detection and manual contour tracing in cardiac multidetector row computed tomography (MDCT) with magnetic resonance imaging (MRI) for calculation of left-ventricular (LV) volumes. The study included 30 patients who underwent contrast-enhanced cardiac MDCT and cardiac cine-MRI. Were calculated 8 mm short-axis slices from MDCT data using three-dimensional multiphase image reconstruction. LV volumes including peak ejection rate and peak filling rate were calculated from manually and semiautomatically determined contours. Results were compared to those from cine-MRI with manually drawn contours as the standard of reference. We found good agreement for the LV volumes, with an ejection fraction of 47.1+/-9.4% for manually drawn contours, 47.9+/-9.9% for semiautomatically detected contours on MDCT, and 48.0+/-10.2% for MRI. Except for peak-filling rate analysis of variance revealed no difference between any of these techniques. Bland-Altman plots and Lin's concordance correlation coefficient showed best agreement between MRI and manual contour tracing in MDCT. Calculation of LV volumes using either semiautomatic or manual contour tracing in cardiac MDCT is therefore feasible when compared to MRI. Automated contour detection needs to be improved to equal manual contour tracing.

Assessment of Global Left Ventricular Function

Evaluation of left ventricular function using electrocardiogram (ECG)-gated multidetector row CT (MDCT) by using 3 different volumetric assessment methods in comparison to assessment of the left ventricular function by invasive ventriculography. Thirty patients with suspected or known coronary artery disease underwent MDCT coronary angiography with retrospective ECG cardiac gating. Raw data were reconstructed at the end-diastolic and end-systolic periods of the heart cycle. To calculate the volumes of the left ventricle, 3 methods were applied: The 3-dimensional data set (3D), the geometric hemisphere cylinder (HC), and the geometric biplane ellipsoid (BE) methods. End-diastolic volumes (EDV), end-systolic volumes (ESV), the stroke volumes (SV), and ejection fractions (EF) were calculated. The left ventricular volumetric data from the 3 methods were compared with measurements from left ventriculography (LVG). The best results were obtained using the 3D method; EDV (r = 0.73), ESV (r = 0.88), and EF (r = 0.76) correlated well with the LVG data. The EDV volumes did not differ significantly between LVG and the 3D method (P = 0.24); however, ESV, SV, and EF differed significantly. The ESV were significantly overestimated (P < 0.01), leading to an underestimation of the SV (P < 0.01) and the EF (P < 0.01). The HC method resulted in the greatest overestimation of the volumes. The EDV and the ESV were 31.8 +/- 37.6% and 136.4 +/- 92.9% higher than the EDV and ESV volumes obtained by LVG. Bland-Altman analysis showed systematic overestimation of the ESV using the HC method. MDCT with retrospective cardiac ECG gating allows the calculation of left ventricular volumes to estimate systolic function. The 3D method had the highest correlation with LVG. However, the overestimation of the ESV is significant, which led to an underestimation of the SV and the EF.

Comparative value of planar versus tomographic acquisitions for the calculation of left ventricular volume with ECG gated equilibrium radionuclide angiography

Comparative value of planar versus tomographic acquisitions for the calculation of left ventricular volume with ECG gated equilibrium radionuclide angiography