Improved accuracy of ejection fraction measurements using a commercial cardiac phantom

Variable ejection fraction results were obtained with a cardiac phantom using different computer systems. The problems was traced to the phantom design. A modification produced more reliable results consistent with expected values.     

Gallbladder ejection fraction: correlation of scintigraphic and ultrasonographic techniques

PURPOSE: The assessment of gallbladder function and ejection fraction using sincalide-enhanced biliary scintigraphy is a useful way to evaluate patients with recurrent right upper quadrant pain but no gallstones. MATERIALS AND METHODS: We wanted to determine whether gallbladder contraction measured by ultrasonography could be used in place of biliary scintigraphy. Biliary scans with an infusion of sincalide and concurrent ultrasonography were performed in 17 patients with histories of recurrent abdominal pain and no evidence of gallstones by ultrasound. RESULTS: Gallbladder ejection fractions calculated by ultrasound and scintigraphy using standard techniques showed only a weak correlation. The poor performance of ultrasound appears to arise because the variable shape of the gallbladder invalidates the calculation of its volume by the formula for a prolate spheroid. When gallbladders that were ellipsoidal were subselected, correlation was improved. The level of training of the sonologist did not have a significant effect on the results. CONCLUSION: Gallbladder ejection fraction calculated by ultrasonography cannot be used routinely as a substitute for biliary scintigraphy.     

Measurement of left ventricular ejection fraction with ionic 113mIn and a cardiac probe

Left ventricular ejection fraction (LVEF) was measured with a cardiac probe (Nuclear Stethoscope, Bios Inc., Valhalla, New York) and ^113mIn in 28 normal subjects and 86 patients with coronary artery disease (CAD). In 20 normal subjects ^99mTC-RBCs were compared with ^113mIn which binds to transferrin after IV injection. With ^99mTc-RBCs, average LVEF was 57±7% (1 SD); with ^113mIn, average LVEF was 55±8% (N.S.). Sequential measurements at different times over 60 min revealed good reproducibility.Comparison of LVEFs obtained using ^99mTc-RBCs with a gamma camera and cardiac probe revealed a good correlation. The correlation coefficients were 0.92 in 25 patients with CAD and 0.95 in 10 patients with LV wall motion abnormalities.The LVEF obtained using a cardiac probe and ^113mIn increased in 28 normals from 57±9% to 64±13% (P<0.001) during handgrip exercise, while the LVEF decreased from 45±9% to 41±10% (P<0.01) in patients with acute myocardial infarction 4–7 weeks after episode, from 48±11 to 40±12% (P<0.001) in patients with old myocardial infarction, and from 52±9 to 42±9% (P<0.001) in patients with angina pectoris.The cardiac probe and ^113mIn provide a useful alternate means of determining left ventricular dysfunction in facilities where ^99mTc and a gamma camera computer system are not readily available.This work supported in part by USPHS Grant No. GM10548.     

Real‐time flow with fast GPU reconstruction for continuous assessment of cardiac output

Purpose:

To demonstrate the feasibility of real‐time phase contrast magnetic resonance (PCMR) assessment of continuous cardiac output with a heterogeneous (CPU/GPU) system for online image reconstruction.

Materials and Methods:

Twenty healthy volunteers underwent aortic flow examination during exercise using a real‐time spiral PCMR sequence. Acquired data were reconstructed in online fashion using an iterative sensitivity encoding (SENSE) algorithm implemented on an external computer equipped with a GPU card. Importantly, data were sent back to the scanner console for viewing. A multithreaded CPU implementation of the real‐time PCMR reconstruction was used as a reference point for the online GPU reconstruction assessment and validation. A semiautomated segmentation and registration algorithm was applied for flow data analysis.

Results:

There was good agreement between the GPU and CPU reconstruction (?0.4 ± 0.8 mL). There was a significant speed‐up compared to the CPU reconstruction (15×). This translated into the flow data being available on the scanner console ≈9 seconds after acquisition finished. This compares to an estimated time using the CPU implementation of 83 minutes.

Conclusion:

Our heterogeneous image reconstruction system provides a base for translation of complex MRI algorithms into clinical workflow. We demonstrated its feasibility using real‐time PCMR assessment of continuous cardiac output as an example. J. Magn. Reson. Imaging 2012; 36:1477–1482. © 2012 Wiley Periodicals, Inc.

     

The radionuclide ejection fraction: a comparison of three radionuclide techniques with contrast angiography

Left-ventricular ejection fraction (EF) can be measured by several radionuclide methods. The EFs determined by three such methods (first-transit time-activity, equilibrium blood-pool time-activity, and equilibrium blood-pool area-length) were compared in 30 patients with EFs measured by area-length analysis of x-ray contrast angiograms. Both time-activity methods (first-transit and blood-pool) yielded EFs that correlated well with x-ray contrast EFs (r=0.86 and 0.84, respectively). Area-length analysis of blood-pool images yielded EFs that agreed less well with x-ray contrast EFs (r=0.73 in the RAO view, 0.70 in the LAO view). We conclude that first-transit and blood-pool techniques are equally accurate methods for determining EF when the time-activity method of analysis is employed.     

Role of cardiac CTA in estimating left ventricular volumes and ejection fraction

Left ventricular ejection fraction (LVEF) is an important predictor of cardiac outcome and helps in making important diagnostic and therapeutic decisions such as the treatment of different types of congestive heart failure or implantation of devices like cardiac resynchronization therapy-defibrillator. LVEF can be measured by various techniques such as transthoracic echocardiography, contrast ventriculography, radionuclide techniques, cardiac magnetic resonance imaging and cardiac computed tomographic angiography (CTA). The development of cardiac CTA using multi-detector row CT (MDCT) has seen a very rapid improvement in the technology for identifying coronary artery stenosis and coronary artery disease in the last decade. During the acquisition, processing and analysis of data to study coronary anatomy, MDCT provides a unique opportunity to measure left ventricular volumes and LVEF simultaneously with the same data set without the need for additional contrast or radiation exposure. The development of semi-automated and automated software to measure LVEF has now added uniformity, efficiency and reproducibility of practical value in clinical practice rather than just being a research tool. This article will address the feasibility, the accuracy and the limitations of MDCT in measuring LVEF.     

Assessment of cardiac wall motion and ejection fraction with gated PET using N-13 ammonia

BACKGROUND: Cardiac gating is not routinely used in cardiac positron emission tomography (PET). The aim of this study was to determine the feasibility of assessing regional wall motion, ejection fraction (EF), cardiac volumes, and mass with nitrogen-13 ammonia (N-13 ammonia) at the time of PET myocardial perfusion imaging. METHODS: We studied 12 healthy volunteers (mean age, 28 +/- 8 years) and 53 patients with documented coronary artery disease (CAD) (mean age, 59 +/- 11 years). All subjects received a single administration of approximately 600 MBq (16 mCi) of N-13 ammonia intravenously. A 6-minute dynamic scan was performed for quantitative assessment of myocardial perfusion at rest, followed by a separate, 13-minute static scan acquired in the gated mode (8 equal bins). Gated data was imported into the Emory Toolbox. Wall motion was evaluated by dividing the myocardium into 9 anatomic regions graded semiquantitatively. RESULTS: Healthy volunteers had a normal EF (61 +/- 6), end systolic volume (ESV) (37 +/- 15 mL), end diastolic volume (EDV) (89 +/- 25 mL), and cardiac mass (116 +/- 18 g). In contrast, patients with CAD showed reduced EF (32 +/- 13%) and increased ESV (129 +/- 56 mL), EDV (188 +/- 68 mL), and cardiac mass (173 +/- 45 g) (P < 0.001 for each). In patients with CAD, EF measured by gated PET correlated significantly to independent measurements of EF (P < 0.001). CONCLUSIONS: Gating of cardiac perfusion images obtained after administration of N-13 ammonia is feasible and appears to be an accurate means of evaluating regional and global cardiac function. Gating can provide important additional diagnostic and prognostic information.     

Assessment of left ventricular ejection fraction with late-systolic and mid-diastolic cardiac phases using multi-slice computed tomography

IntroductionMulti-slice computed tomography (MSCT) is an accurate tool for the assessment of left ventricular ejection fraction (LVEF). However, in order to reduce radiation dose, prospective acquisition protocols are currently used, in which the end-systole and end-diastole are not scanned. Our aim was to study the accuracy of the assessment of LVEF using fixed late-systolic and mid-diastolic cardiac phases compared with echocardiography.MethodsMSCT-derived LVEF was measured with off-line commercially available software packages, and compared with echocardiography-derived LVEF using the Simpson's method. LVEF was categorized as normal vs. abnormal (50% cut-off) and was also analyzed as a quantitative parameter. Bland-Altman plots and Pearson correlations were used for inter-technique comparisons.Results58 patients were included. The sensitivity and specificity of fixed-phase MSCT when compared with echocardiography for detection of LVEF ≤50% was 79% (95% CI = 65–89%) and 43% (10–82%). Misclassification was associated with older age (68 ± 12 vs. 54 ± 13 years, p < 0.01), faster heart rate (79 ± 14 vs. 68 ± 10 bpm, p = 0.01), and LV hypertrophy (86% vs. 52%, p = 0.03). The quantitative comparison revealed no correlation (r = 0.095, p = 0.478) and a significantly different LVEF (median[IQR], 57.0[50.5–63.1]% vs. 61.0[57.3–64.3]%, p = 0.03). The observed bias between the two methods was −3.7% with broad limits of agreement (±25.5%).ConclusionsFixed-phase MSCT assessment using late-systole and mid-diastole agreed in defining normal and abnormal LVEF in 76% of patients when compared with echocardiography. Quantitation of LVEF by this method yielded significantly lower values of LVEF and showed no correlation. Thus, accurate quantitation of LVEF by MSCT requires the acquisition of end-systolic and end-diastolic phases.     

Assessment of cardiac wall motion with the ejection fraction image: a comparison with contrast left ventriculography

Twenty patients with ischemic heart disease were studied with biplane contrast left ventriculography and gated bloob pool scans. An ejection fraction (EF) image was calculated from each gated blood pool scan. The EF image and contrast ventriculograms were divided into three regions and seven segments respectively. The sites of asynergy observed in each study were compared. Segments two, three and six of the contrast ventriculogram corresponded to the anteroseptal and inferoapical regions of the EF image, but it was difficult to differentiate between these segments on the EF image. Segments three and four corresponded to the inferoapical region and segments five and seven corresponded to the posterolateral region. Diffuse asynergy with a low EF (less than 30%) causes a large defect on the EF image. The mean regional EF obtained from the EF image correlated well with the EF calculated from the left ventricular volume curve (n = 50, r = 0.94).     

Evaluation of left ventricular volumes and ejection fraction by gated SPECT and cardiac MRI in patients with dilated cardiomyopathy

Purpose  

The goal of this study was to evaluate the accuracy of gated single photon emission computed tomography (SPECT) in the assessment of left ventricular (LV) end-diastolic/end-systolic volumes (EDV, ESV) and ejection fraction (LVEF) in patients with dilated cardiomyopathy, using cardiac magnetic resonance imaging (MRI) as the reference method. Furthermore, software-specific characteristics of Quantitative Gated SPECT (QGS), Emory Cardiac Toolbox (ECTB) and 4D-MSPECT were analysed.     

Right ventricular volumes and ejection fraction with fast cine MR imaging in breath-hold technique: applicability, normal values from 52 volunteers, and evaluation of 325 adult cardiac patients

Our goal was to establish right ventricular (RV) volume and ejection fraction (EF) values in normal volunteers with fast magnetic resonance (MR) imaging using a breath-hold technique, to assess the frequency and severity of RVEF abnormality in cardiac patients and to compare RV with left ventricular (LV) data. We performed simultaneously derived RV and LV fast cine measurements in 52 normals and 325 patients with coronary artery disease (CAD), acquired valvular disease (VD), cardiomyopathy (CM), or congenital heart disease (CHD). RVEF was reduced in 31% (102) of all patients, in 50% dilated CM, 39% CHD, 34% CAD, and 22% acquired VD patients. Solitary abnormally low RVEF was found in only 15/325 (5%) of all patients, whereas combined with LVEF deterioration in 87/172 (51%) patients. RVEF reduction was mild in 64%, moderate in 25%, and severe in 11%. Although RVEF correlated significantly (r = 0.55, P < 0.001) with LVEF, the predictive value of LVEF for RVEF was low. We conclude that RV volumes can be routinely assessed with fast MRI and should be performed in addition to LV evaluation in CHD, in right-sided VD, and in all patients with an abnormal LVEF.J. Magn. Reson. Imaging 1999; 10:908-918.     

Correlation of effective temporal resolution and accuracy of volume ejection fraction on the ECG-gated cardiac MDCT

PURPOSE: ECG-gated cardiac MDCT offers many cardiac clinical applications. The goals of this report are 1) to introduce a new concept of effective reliability (ER) from effective temporal resolution for the evaluation of ejection fraction (EF) and evaluation of image quality (IQ) of coronary arteries, and 2) to show the correlation of ER and the accuracy of EF with different cardiac reconstruction algorithms and different rotation speeds. METHODS AND MATERIALS: To assess the accuracy of EF, helical scanning was performed with a gated cardiac MDCT (GE LightSpeed, 8/16 slice) on pulsating cardiac coronary phantoms (0.5 and 0.6 sec rotation speed for each 50-110 bpm, 5-bpm step). We define effective reliability (ER) from effective temporal resolution (%) as follows: ER= (1-TR/HC) x 100; TR: Effective temporal resolution, HC: time of heart cycle in each bpm. RESULTS: From the results of the EF measurement and calculated ER, high accuracy was obtained by using optimal scan conditions (optimal rotation speed and cardiac reconstruction algorithm) in a wide range of heart rates (heart rate<90: EF & ER>81%; heart rate<110 bpm: EF & ER>73%). Results showed that the calculated ER is closely correlated with the measurement results of EF based on the phantom experiment (R2=0.901+/-0.075; Max: 0.994, Min: 0.738). Optimal reconstruction thickness can reduce total image number for the evaluation of EF. CONCLUSION: We concluded that the ER is useful to evaluate EF accuracy and the IQ of images of coronary arteries.     

Evaluation of left ventricular volumes and ejection fraction by gated myocardial perfusion SPECT versus cardiac MRI

It is stated that cardiac MRI imaging can provide accurate estimation of left ventricular (LV) volumes and ejection fraction (EF). The purpose of this study was to evaluate the accuracy of gated myocardial perfusion SPECT for assessment of LV end-diastolic volume (EDV), end-systolic volume (ESV) and EF, using cardiac MRI as the reference methods/(methodology). Gated myocardial perfusion SPECT images were analyzed with two different quantification software, QGS and 4D-MSPECT. Thirty-four consecutive patients were studied. Myocardial perfusion SPECT and cardiac MRI had excellent intra/interobserver reproducibility. Correlation between the results of gated myocardial perfusion SPECT and cardiac MRI were high for EDV and EF. However, ESV and EDV were significantly underestimated by gated myocardial perfusion SPECT compared to cardiac MRI. Moreover, gated myocardial perfusion SPECT overestimated EF for small heart. One reason for the difference in volumes and EF is the delineation of the endocardial border. Cardiac MRI has higher spatial resolution. We should understand the differences of volumes and EF as determined by gated myocardial perfusion SPECT and cardiac MRI.     

Correlation of carotid blood flow and corrected carotid flow time with invasive cardiac output measurements

Background

Non-invasive measures that can accurately estimate cardiac output may help identify volume-responsive patients. This study seeks to compare two non-invasive measures (corrected carotid flow time and carotid blood flow) and their correlations with invasive reference measurements of cardiac output. Consenting adult patients (n = 51) at Massachusetts General Hospital cardiac catheterization laboratory undergoing right heart catheterization between February and April 2016 were included. Carotid ultrasound images were obtained concurrently with cardiac output measurements, obtained by the thermodilution method in the absence of severe tricuspid regurgitation and by the Fick oxygen method otherwise. Corrected carotid flow time was calculated as systole time/√cycle time. Carotid blood flow was calculated as π × (carotid diameter)²/4 × velocity time integral × heart rate. Measurements were obtained using a single carotid waveform and an average of three carotid waveforms for both measures.

Results

Single waveform measurements of corrected flow time did not correlate with cardiac output (ρ = 0.25, 95% CI ?0.03 to 0.49, p = 0.08), but an average of three waveforms correlated significantly, although weakly (ρ = 0.29, 95% CI 0.02–0.53, p = 0.046). Carotid blood flow measurements correlated moderately with cardiac output regardless of if single waveform or an average of three waveforms were used: ρ = 0.44, 95% CI 0.18–0.63, p = 0.004, and ρ = 0.41, 95% CI 0.16–0.62, p = 0.004, respectively.

Conclusions

Carotid blood flow may be a better marker of cardiac output and less subject to measurements issues than corrected carotid flow time.

     

Direct cardiac NMR imaging of heart wall and blood flow velocity

Nuclear magnetic resonance (NMR) imaging is used to produce in the same scan both anatomical and functional information of the heart and great vessels. A method is described to generate velocity images by the use of phase shifts for moving spins induced by imaging gradients under electrocardiogram (ECG) synchronized imaging conditions. The influence of the different gradients is discussed together with methods to obtain velocity information for each gradient direction separately. The results, obtained with a 0.14 T resistive NMR scanner and normal volunteers, show the spatial velocity distribution in the aorta and heart walls in color scale images. The feasibility of velocity calculations is demonstrated and some applications are given. The present results indicate the possibility of quantitative flow and motion analysis with ECG synchronized NMR imaging.     

Comparison of left ventricular ejection fraction by EKG-gated radionuclide techniques and contrast angiography using a microcomputer system.

The left ventricular ejection fractions of 53 patients were determined from multi-image cardiac blood pool scintigrams in the left anterior oblique position utilizing a microcomputer and floppy disc. These data were compared to ejection fractions obtained at cardiac catheterization in the right anterior oblique position. The ejection fraction obtained by radionuclide technique was comparable to that obtained by contrast angiography in the 53 patients with an r = 0.93. Forty-five patients with coronary artery disease showed an r = 0.92. In the coronary artery group with regional wall dysfunction, the correlation was r = 0.89.     

Gated blood-pool SPECT versus cardiac magnetic resonance imaging for the assessment of left ventricular volumes and ejection fraction

Background  

We evaluated the accuracy of planar radionuclide angiography and different count-based and space-based electrocardiogram (ECG)-gated blood-pool single-photon emission computed tomography (GBPS) algorithms for assessment of left ventricular end-diastolic volume (LVEDV), end-systolic volume (LVESV), and ejection fraction (LVEF) compared with the gold standard of cardiac magnetic resonance imaging (cMRI). The goal is to assess the accuracy of a recently developed GBPS algorithm.