Effect of sex, age, and weight on ejection fraction and end-systolic volume reference limits in gated myocardial perfusion SPECT

CMR validation of left ventricular volumes and ejection fraction measured by the IQ-SPECT system in patients with small heart size

BACKGROUND

The IQ-SPECT system is equipped with multifocal collimators and uses ordered-subset conjugate gradient minimization (OSCGM) as its reconstruction algorithm, achieving a shorter acquisition time than conventional SPECT. Left ventricular ejection fraction (LVEF) is overestimated by conventional SPECT in patients with small heart size. In this study, we compared IQ-SPECT with conventional SPECT and cardiovascular magnetic resonance (CMR) for the estimation of LVEF in patients with small hearts (males: EDV ≤ 60 ml, ESV ≤ 25 ml; females: EDV ≤ 45 ml, ESV ≤ 20 ml).

METHODS

The study consisted of 49 consecutive patients (20 normal and 29 with small heart size) undergoing gated myocardial perfusion imaging (GMPI) with a 99mTc-labelled agent during stress or rest to assess the risk of coronary artery disease (CAD). The data were reconstructed using filtered back-projection (FBP) for conventional SPECT and OSCGM for IQ-SPECT. ESV, EDV, and LVEF were calculated using quantitative gated SPECT (QGS). To determine the optimal ordered-subset reconstruction parameters, we compared the LVEF from SPECT to the corresponding measurement from CMR.

RESULTS

EDV, ESV, and LVEF values obtained from IQ-SPECT and conventional SPECT showed that the results of these two forms of SPECT were significantly correlated, although the EDV and ESV obtained by IQ-SPECT were higher than those obtained by conventional SPECT. IQ-SPECT yielded lower LVEF measurements than conventional SPECT (normal heart size: 50.6 ± 4.3% vs. 73.4 ± 8.4%, P = 0.002; small heart size: 62.1 ± 7.8% vs. 75.0 ± 11.4%, P < 0.001). There were no significant differences in LVEF measurements made by IQ-SPECT and CMR (normal heart size: 50.6 ± 4.3% vs. 53.2 ± 5.8%, P > 0.05; small heart size: 62.1 ± 7.8% vs. 64.6 ± 8.8%, P > 0.05). Five subsets (S) and 12 iterations (I) did not differ significantly in LVEF between CMR and IQ-SPECT for patients with small hearts (64.6 ± 8.8% vs. 62.1 ± 7.8%, P = 0.120), while 3 S and 10 I were the best parameters for patients with normal heart size (50.6 ± 4.3% vs. 53.1 ± 5.8%, P = 0.117).

CONCLUSION

With CMR as the standard, IQ-SPECT yields more reliable LVEF values than conventional SPECT for populations with small heart size. The best reconstruction parameters from IQ-SPECT were 5 S and 12 I for patients with small hearts.

Relationship between Semi-Quantitative Parameters of Thallium-201 Myocardial Perfusion Imaging and Coronary Artery Disease

This study aimed to investigate the diagnostic performance of semi-quantitative parameters of thallium-201 myocardial perfusion imaging (MPI) for coronary artery disease (CAD). From January to December 2017, patients were enrolled who had undergone Tl-201 MPI and received cardiac catheterization for coronary artery disease within three months of MPI. Receiver operating characteristics (ROC) analysis was used to determine the optimal cutoff values of semi-quantitative parameters. A comparison of the sensitivity and specificity of these parameters based on different subgroupings was further performed. A total of 130 patients were enrolled for further analysis. Among the collected parameters, the stress total perfusion deficit (sTPD) had the highest value of the area under curve (0.813) under the optimal cutoff value of 3.5%, with a sensitivity and specificity of 73.5% and 74.5%, respectively (p = 0.0000), for the diagnosis of CAD. With further subgrouping analysis based on history of diabetes or dyslipidemia, the sensitivity and specificity showed similar results. Based on the currently collected data and image acquisition conditions, the sTPD parameter has a clinical role for the diagnosis of CAD with a cutoff value of 3.5%.

Ratiology and a Complementary Class of Metrics for Cardiovascular Investigations

Cardiovascular investigations often involve ratio-based metrics or differences: ejection fraction, arterial pressure augmentation index, coronary fractional flow reserve, pulse pressure. Focusing on a single number (ratio or difference) implies that information is lost. The lost companions constitute a well-defined but thus far unrecognized class, having additive value, a physical dimension, and often a physiological meaning. Physiologists should play a prominent role in exploring these complementary avenues and also define alternatives.

Heart Failure Phenotypes Require Sex-Specific Criteria Which Are Based on Ventricular Dimensions

Ejection fraction (EF) is often used as a criterion to establish diagnostic phenotypes of heart failure (HF). Because EF is a derived metric based on end-systolic volume (ESV) and end-diastolic volume (EDV), it is more logical to consider ESV or EDV as cut-off marker. We concentrate on the impact of ESV, which has the advantage of being linearly related to EDV and nonlinearly with EF, both with highly significant correlations. In particular we also analyze if HF classification should distinguish between females and males.ESV and EDV were determined by biplane angiography in 197 HF patients (67 women). As body surface indexed (i) ESVi values for adult healthy females are smaller than for males, we employ classes of ESVi (bins of 10 mL/m²) to group preserved and reduced EF's (cut-off at 50%) for HF. Reference values regarding mean and standard deviation for ESVi are based on a control group (N=155, 65 women) without HF. For interpretation of the findings we use the documented universal relationship connecting EF to ESV: EF = 1 + c₁ {ESV / (c₂ - ESV)}, where c₁ and c₂ are population-based sex-independent constants. In the reference group ESVi (mL/m²) in women (27.4 ± 27.6) is smaller (P=0.0026) than in their male counterparts (43.6 ± 37.5). Similarly, for HF the ESVi in women (45.7 ± 41.4) is smaller (P=0.0033) than in men (64.2 ± 41.4). This signifies (see formula above) that women have higher values for EF, primarily resulting from smaller ventricular size related to their sex, and not exclusively reflecting disease state. Current phenotype classification based on pooled data for males and females may be inappropriate for either sex.The significantly smaller ESVi observed in women has direct consequences for the traditional classification based on EF cutoff values for HF. Sex-specific criteria (regarding ESVi or EF) for HF phenotypes are warranted, and expectedly have substantial consequences for identification, classification, and management of HF patients.

Sex- and Age-Related Reference Values in Cardiology, with Annotations and Guidelines for Interpretation

The definition of "abnormal" in clinical sciences is often based on so-called reference values which point to a range that experts by some sort of consensus consider as normal when looking at biological variables. Such a level is commonly calculated by taking (twice) the standard deviation from the mean, or considering certain percentiles. The suspicion or even confirmation of a disease is then established by demonstrating that the value measured exceeds the upper or lower reference value. As is often the case, the measurement accuracy may depend on the conditions and specific method employed to collect and analyze data. This implies that, for example, data assessed by 2D echocardiography possibly differ from those obtained by MRI and therefore require modality-specific reference values. In this review we summarize reference values for the electrocardiogram, cardiac compartmental volumes, and arterial vessel size in males and females for various age groups. These values may further depend on other variables such as body size, physical training status, and ethnicity. Additional variables relevant for cardiology such as those referring to the microcirculation and biomarkers are only mentioned with reference to the pertinent literature. In general, the sex- and age-specific differences observed are often remarkable and warrant consideration in clinical practice and basic biomedical sciences.

Heart Transplantation Survival and Sex-Related Differences

Orthotopic heart transplantation (OHT) is the "gold standard" treatment for patients with end-stage heart failure, with approximately 5000 transplants performed each year worldwide. Heart transplantation survival rates have progressively improved at all time points, despite an increase in donor and recipient age and comorbidity and greater recipient urgency; according to the registry of the International Society of Heart and Lung Transplantation (ISHLT), the median survival of patients posttransplantation is currently 12.2 years.Long-term survival is sub-optimal, and outcomes after OHT remain constrained by the development of acute rejection and cardiac allograft vasculopathy (CAV). Moreover, donor organs are in short supply, making optimal organ utilization an ongoing priority. For these reasons, substantial interest continues to exist in identifying factors portending increased survival and improved organ utilization.

Cardiophysiology Illustrated by Comparing Ventricular Volumes in Healthy Adult Males and Females

Recent advances in cardiac imaging techniques have substantially contributed to a growing interest in the analysis of global cardiac chamber dimensions and regional myocardial deformation. During the cardiac cycle, ventricular luminal volume varies due to the contraction process, which also confers a shape change including substantial alteration of long axis length, as well as rotation of the base compared to the apex. Local deformation can be assessed by strain (rate) analysis. Reviewing the present literature, it must be concluded that there is no single metric available to comprehensively characterize ventricular function. Every candidate advanced thus far has been found to incompletely reflect ventricular performance. This observation is not surprising in view of the complexity of the cardiac pump system. Additionally, sex-specific modifiers may play a role. More than three decades ago, it was shown that on average the ventricular volume is smaller in healthy women compared to matched males. Therefore, the present contribution concerns the interpretation of data derived from the healthy heart in both men and women. Starting from the classical Starling concept, we apply a simple mathematical transformation which permits an insightful representation of ventricular mechanics. Relating end-systolic volume (ESV) to end-diastolic volume creates the ventricular volume regulation graph which features the pertinent working point of an individual heart. This fundamental approach illustrates why certain proposed performance indexes cannot individually reveal the essence of ventricular systolic function. We demonstrate that particular metrics are highly interconnected and just tell us the same story in a different disguise. It is imperative to understand which associations exist and if they expectedly are (nearly) linear or frankly nonlinear. Notably, ejection fraction (EF) is primarily determined by ESV, while in turn EF is not much different from ventriculo-arterial coupling (VAC). Insight into cardiac function is promoted by identification of the paramount/essential components involved. The smaller ESV (p < 0.0001) implies that EF is higher in women and may also have consequences for VAC.

Distribution of cardiac output to the brain across the adult lifespan

A widely accepted dogma is that about 15-20% of cardiac output is received by the brain in healthy adults under resting conditions. However, it is unclear if the distribution of cardiac output directed to the brain alters across the adult lifespan and is modulated by sex or other hemodynamic variables. We measured cerebral blood flow/cardiac output ratio index in 139 subjects (88 women, age 21-80 years) using phase-contrast magnetic resonance imaging and echocardiography. Body mass index, cardiac systolic function (eject fraction), central arterial stiffness (carotid-femoral pulse wave velocity), arterial pressure, heart rate, physical fitness (VO2 max), and total brain volume were measured to assess their effects on the cardiac output-cerebral blood flow relationship. Cerebral blood flow/cardiac output ratio index decreased by 1.3% per decade associated with decreases in cerebral blood flow ( P < 0.001), while cardiac output remained unchanged. Women had higher cerebral blood flow, lower cardiac output, and thus higher cerebral blood flow/cardiac output ratio index than men across the adult lifespan. Age, body mass index, carotid-femoral pulse wave velocity, and arterial pressure all had negative correlations with cerebral blood flow and cerebral blood flow/cardiac output ratio index ( P < 0.05). Multivariable analysis adjusted for sex, age showed that only body mass index was negatively associated with cerebral blood flow/cardiac output ratio index (β = -0.33, P < 0.001). These findings demonstrated that cardiac output distributed to the brain has sex differences and decreases across the adult lifespan and is inversely associated with body mass index.

Sex-specific aspects of left and right ventricular volume regulation in patients following tetralogy of Fallot repair

Ejection fraction (EF) is applied as a clinically relevant metric to assess both left (LV) and right ventricular (RV) function. EF depends on the interplay between end-systolic volume (ESV) and end-diastolic volume (EDV). The role of the two constitutive components is of particular interest for the follow-up study of Fallot patients at risk for RV volume overload. The volume regulation graph (VRG) relates ESV to EDV and has been advanced as a central tool to describe LV and RV function. The method permits additional analysis of the impact of clinically relevant determinants such as sex and age. Following Fallot repair and using MRI we evaluated LV and RV volumes in 124 patients (50 females), who were not taking any medication. Volumes were indexed for body surface area (BSA). The VRG regression lines are similar for both sexes, also when stratified for age (i.e. younger or older than 18 years), and different for LV and RV. However, RV ESV is larger (P=0.039) for adult males, as is RV EDV (P=0.026) in boys, relative to their female counterparts. For LV ESV we also found larger volumes, but only in boys (P=0.023) compared to girls. Average EF (only for RV) is lower in adult men compared to women (P=0.012), and to boys (P=0.007). These findings are partly in contrast with common observations made in individuals without a history of cardiac disease, where (with BSA indexation) LV and RV volumes are similar in children, but consistently larger in adult males. These results highlight the age- and sex-specific volumetric aspects of remodeling following surgery in Fallot patients, and emphasize the pivotal role of ESV size in both RV and LV.

Monte Carlo method applied to the evaluation of the relationship between ejection fraction and its constituent components

Ventricular function is routinely assessed by applying the clinically accepted metric ejection fraction (EF). The numerical value of EF depends on the interplay between end-systolic volume (ESV) and end-diastolic volume (EDV). The relative impact of the two constitutive components has received little attention. Pediatric cardiologists are interested in EF vs ESV when evaluating various congenital abnormalities. Following successful surgical intervention of Fallot tetralogy, many of these patients receive follow-up, not only during childhood, but also when being adults. Cardiologists diagnosing and treating elderly patients often analyze EF vs EDV, notably for phenotyping heart failure patients. Therefore, we study EF vs ESV as well as EF vs EDV in more detail. We explore the fundamentals of EF while analyzing a Fallot patient group. Three routes were followed, namely nonlinear regression, by implementing a Monte Carlo approach to generate EDV on the basis of known ESV values, and by using a theoretical graphical derivation. Our MRI-based post Fallot repair study includes left (LV) and right ventricular (RV) data (N=124). Using a robust approach we employed nonlinear regression with ESV as an independent variable. EDV was also assessed by Monte Carlo generated values for stroke volume within a physiological range. In all cases ESV emerges as the dominant component of EF, with less (P<;0.0001) impact of EDV. Using three independent routes we demonstrate that values for EF primarily depend on the corresponding ESV. This relationship is nonlinear, and correlation is always better with ESV compared to EDV in these patients, and confirmed in random number modeling studies.

In vivo validation of gated myocardial SPECT imaging for quantification of small hearts: comparison with cardiac MRI

BACKGROUND

In patients with small hearts, the Quantitative Gated single-photon emission computed tomography (SPECT) (QGS) program frequently underestimates the left ventricular (LV) end-systolic volume (ESV) and overestimates the ejection fraction (EF). A newly developed cardiac software program, cardioREPO/EXINI heart (cREPO), has been proposed to more accurately quantify small hearts using active shape modeling and a volume-dependent edge correction algorithm for LV delineation. The aim of this study was to validate cREPO in vivo for measuring the LV volumes and EF of both small and non-small hearts, in comparison with values obtained via cardiac MRI (CMR).

METHODS

We performed stress (99m)Tc-MIBI SPECT and CMR within a 30-day interval for 44 patients (mean age, 66 years; 27 men). Resting EF, end-diastolic volume (EDV), and ESV with QGS and cREPO were compared with values obtained via CMR.

RESULTS

The subjects consisted of 17 small and 27 non-small hearts. CMR yielded EDV, ESV, and EF values of 135 ± 31 ml (mean ± SD, range 85-217 ml), 57 ± 21 ml (27-105 ml), and 60 ± 6 % (45-70 %), respectively. Compared with CMR, both QGS and cREPO systematically underestimated both EDV and ESV and overestimated EF. The magnitude of the overestimation of EF by QGS, compared with CMR, correlated strongly with the given EF values (r = 0.71, P < 0.0001). In contrast, no significant correlation was seen with cREPO (r = 0.18, P = 0.24). In addition, no significant correlation was found between the magnitude of the underestimation of ESV and heart size with cREPO (r = 0.03, P = 0.83). Thus, cREPO provided a relatively constant 9 % overestimation of EF values relative to CMR, for the studied EF range for both small and non-small hearts.

CONCLUSIONS

The use of the new algorithm of cREPO ameliorated exaggerated EF in small hearts but not resolved completely. The program provided a constant 9 % overestimation for both small and non-small hearts, which should be carefully taken into account for clinical assessment of LV function.

Hemodynamic determinants and ventriculo-arterial coupling are sex-associated in heart failure patients

End-systolic volume (ESV) and end-diastolic volume (EDV) are key parameters in the analysis of left ventricular (LV) function, and the study of cardiac remodeling. The volume regulation graph (VRG) relates these fundamental determinants, and permits convenient stratification for clinically relevant covariates. This contribution analyzes sex-associated differences in hemodynamic parameters for 197 heart failure (HF) patients, evaluated by biplane ventriculography, in combination with arterial pressure. We calculated LV parameters such as stroke volume (SV), cardiac output (CO), ESV, EDV, ejection fraction (EF), end-systolic elastance (Emax), besides arterial parameters: effective arterial elastance (Ea), elastance ratio (the coupling index k), peripheral resistance (Rs), pulse pressure (PP), and arterial compliance (C), all normalized for body surface area when appropriate. Average values for heart rate, SV, CO, Ea, C, Rs are similar between the sexes, as are the VRG regression lines. However, ESV and EDV are significantly (P<;0.034 and P<;0.016, respectively) smaller in women (N=67), whereas EF, Emax, mean arterial pressure, PP, and k are higher (P<;0.008 or less). We conclude that the various sex-associated differences observed in these HF patients are striking, and thus require due attention when evaluating the clinical status of HF patients. Formulation of distinct cut-off values for male and female patients with HF seems warranted, when considering specific HF phenotypes.

Cohort of estrogen-induced microRNAs regulate adrenomedullin expression

Estrogen regulates the expression of many genes and has been correlated with differences in cardiac contraction; however, the underlying mechanisms remain poorly defined. Adrenomedullin (Adm = gene; AM = protein) is a multifunctional peptide with inotropic actions. Previous studies have demonstrated that estrogen enhances the expression of Adm, suggesting a relationship between AM and estrogen in cardiac contraction during physiological and pathological states. In this study, female mice in a mouse model of genetic Adm overexpression, abbreviated as Adm(hi/hi), were found to express 60 times more Adm in the heart than wild-type littermates, compared with the three-fold elevation of Adm previously reported in Adm(hi/hi) male hearts. Thus, this study sought to further investigate any functional consequences of increased cardiac Adm expression and begin exploring the mechanisms that regulate Adm expression in an estrogen-dependent fashion. This study revealed that heart function is enhanced in Adm(hi/hi) females, which along with Adm expression levels, was reversed following ovariectomization. Since the Adm(hi/hi) line was generated by the displacement of the 3' untranslated region (UTR), the native 3'UTR was examined for estrogen-induced microRNAs target sites to potentially explain the aberrant overexpression observed in Adm(hi/hi) female hearts. Using a bioinformatic approach, it was determined that the mouse Adm 3'UTR contains many target sites for previously characterized estrogen-induced microRNAs. This study also determined that the novel microRNA, miR-879, is another estrogen-induced microRNA that interacts with the 3'UTR of Adm to destabilize the mRNA. Together, these studies revealed that estrogen-induced microRNAs are important for balancing cardiac Adm expression in females.

Gated SPECT evaluation of left ventricular function using a CZT camera and a fast low-dose clinical protocol: comparison to cardiac magnetic resonance imaging

PURPOSE

CZT technology allows ultrafast low-dose myocardial scintigraphy but its accuracy in assessing left ventricular function is still to be defined.

METHODS

The study group comprised 55 patients (23 women, mean age 63 ± 9 years) referred for myocardial perfusion scintigraphy. The patients were studied at rest using a CZT camera (Discovery NM530c; GE Healthcare) and a low-dose (99m)Tc-tetrofosmin clinical protocol (mean dose 264 ± 38 MBq). Gated SPECT imaging was performed as a 6-min list-mode acquisition, 15 min after radiotracer injection. Images were reformatted (8-frame to 16-frame) using Lister software on a Xeleris workstation (GE Healthcare) and then reconstructed with a dedicated iterative algorithm. Analysis was performed using Quantitative Gated SPECT (QGS) software. Within 2 weeks patients underwent cardiac magnetic resonance imaging (cMRI, 1.5-T unit CVi; GE Healthcare) using a 30-frame acquisition protocol and dedicated software for analysis (MASS 6.1; Medis).

RESULTS

The ventricular volumes obtained with 8-frame QGS showed excellent correlations with the cMRI volumes (end-diastolic volume (EDV), r = 0.90; end-systolic volume (ESV), r = 0.94; p < 0.001). However, QGS significantly underestimated the ventricular volumes (mean differences: EDV, -39.5 ± 29 mL; ESV, -15.4 ± 22 mL; p < 0.001). Similarly, the ventricular volumes obtained with 16-frame QGS showed an excellent correlations with the cMRI volumes (EDV, r = 0.92; ESV, r = 0.95; p < 0.001) but with significant underestimations (mean differences: EDV, -33.2 ± 26 mL; ESV, -17.9 ± 20 mL; p < 0.001). Despite significantly lower values (47.9 ± 16 % vs. 51.2 ± 15 %, p < 0.008), 8-frame QGS mean ejection fraction (EF) was closely correlated with the cMRI values (r = 0.84, p < 0.001). The mean EF with 16-frame QGS showed the best correlation with the cMRI values (r = 0.91, p < 0.001) and was similar to the mean cMRI value (49.6 ± 16 %, p not significant). Regional analysis showed a good correlation between both 8-frame and 16-frame QGS and cMRI wall motion score indexes (8-frame WMSI, r = 0.85; 16-frame WMSI, r = 0.89; p < 0.01).

CONCLUSION

Low-dose gated SPECT with a CZT camera provides ventricular volumes that correlate well with cMRI results despite significant underestimation in the measure values. EF estimation appeared to be more accurate with 16-frame reformatted images than with 8-frame images.

Improved quantification of small hearts for gated myocardial perfusion imaging

PURPOSE

In patients with a small heart, defined as an end-systolic volume (ESV) of ≤20 mL calculated using the Quantitative Gated SPECT (QGS) program, underestimation of ESV and overestimation of ejection fraction (EF) using gated myocardial perfusion imaging are considered errors caused by inappropriate delineation of the left ventricle (LV). The aim of this study was to develop a new method for delineation of the LV and to evaluate it in studies using a digital phantom, normal subjects and patients.

METHODS

The active shape-based method for LV delineation, EXINI heart (ExH), was adjusted to more accurately process small hearts. In small hearts, due to the partial volume effect and the short distance to the opposite ventricular wall, the endocardial and the epicardial surfaces are shifted in the epicardial direction depending on the midventricular volume. The adjusted method was evaluated using digital XCAT phantoms with Monte Carlo simulation (8 virtual patients), a Japanese multicentre normal database (69 patients) and consecutive Japanese patients (116 patients). The LV volumes, EF and diastolic parameters derived from ExH and QGS were compared.

RESULTS

The digital phantom studies showed a mean ESV of 87% ± 9% of the true volume calculated using ExH and 22 % ± 18% calculated using QGS. In the normal database, QGS gave higher EFs in women than in men (71.4 ± 6.0 % vs. 67.2 ± 6.0%, p = 0.0058), but ExH gave comparable EFs (70.7 ± 4.9% and 71.4 ± 5 % in men and women, respectively, p = ns). QGS gave higher EFs in subjects with a small heart than in those with a normal-sized heart (74.5 ± 5.1% vs. 66.1 ± 4.9%), but ExH gave comparable values (70.0 ± 5.9% vs. 71.6 ± 4.2%, respectively, p = ns). In consecutive patients, the average EFs with QGS in patients with ESV >20 mL, 11-20 mL and ≤10 mL were 57.9%, 71.9% and 83.2%, but with ExH the differences among these groups were smaller (65.2%, 67.8% and 71.5%, respectively).

CONCLUSION

The volume-dependent edge correction algorithm was able to effectively reduce the effects on ESV and EF of a small heart. The uniform normal values might be applicable to both men and women and to both small and normal-sized hearts.

Sex-specific normal limits of left ventricular ejection fraction and volumes estimated by gated myocardial perfusion imaging in adult patients in Taiwan: a comparison between two quantitative methods

BACKGROUND

The left ventricular (LV) ejection fraction (EF) and end-diastolic and end-systolic volumes are strong predictors for prognosis of cardiac death. Quantitative-gated myocardial perfusion single-photon emission computed tomography (SPECT) is widely used to measure LV functional parameters. However, systematic differences may exist between referred populations. We sought to derive sex-specific normal values for LV functional parameters obtained using two quantitative methods.

METHODS

Among 1044 consecutive patients who underwent dipyridamole stress myocardial perfusion-gated 201Tl SPECT in 2008, a total of 140 (56 men) with normal perfusion imaging were selected. None had cardiac diseases or experienced cardiac events during 1-year follow-up. LV EF and end-diastolic and end-systolic volumes were calculated by quantitative-gated SPECT (QGS) and four-dimensional-myocardial single photon emission computed tomography (4D-MSPECT), respectively.

RESULTS

There was excellent intrareader and interreader reproducibility for both QGS and 4D-MSPECT algorithms. The differences in LV volumes and EF between the software packages were small. High prevalence of small heart was noted in the study population, especially in women (>60%). Volumetric measures were significantly greater (P<0.001) in men than in women, even after adjustment for body surface area. Women had a higher LV EF than men when using QGS methods, but not when using the 4D-MSPECT method. Compared with 4D-MSPECT, sex remained significantly associated with EF determined by QGS methods, independent of age and body weight.

CONCLUSION

LV functional parameters determined by means of gated 201Tl SPECT need to be corrected for sex and algorithms. Separate reference values of LV EF and volumes need to be applied in both women and men depending on the software package used.

Computer-assisted determination of left ventricular endocardial borders reduces variability in the echocardiographic assessment of ejection fraction

BACKGROUND

Left ventricular size and function are important prognostic factors in heart disease. Their measurement is the most frequent reason for sending patients to the echo lab. These measurements have important implications for therapy but are sensitive to the skill of the operator. Earlier automated echo-based methods have not become widely used. The aim of our study was to evaluate an automatic echocardiographic method (with manual correction if needed) for determining left ventricular ejection fraction (LVEF) based on an active appearance model of the left ventricle (syngo AutoEF, Siemens Medical Solutions). Comparisons were made with manual planimetry (manual Simpson), visual assessment and automatically determined LVEF from quantitative myocardial gated single photon emission computed tomography (SPECT).

METHODS

60 consecutive patients referred for myocardial perfusion imaging (MPI) were included in the study. Two-dimensional echocardiography was performed within one hour of MPI at rest. Image quality did not constitute an exclusion criterion. Analysis was performed by five experienced observers and by two novices.

RESULTS

LVEF (%), end-diastolic and end-systolic volume/BSA (ml/m2) were for uncorrected AutoEF 54 +/- 10, 51 +/- 16, 24 +/- 13, for corrected AutoEF 53 +/- 10, 53 +/- 18, 26 +/- 14, for manual Simpson 51 +/- 11, 56 +/- 20, 28 +/- 15, and for MPI 52 +/- 12, 67 +/- 26, 35 +/- 23. The required time for analysis was significantly different for all four echocardiographic methods and was for uncorrected AutoEF 79 +/- 5 s, for corrected AutoEF 159 +/- 46 s, for manual Simpson 177 +/- 66 s, and for visual assessment 33 +/- 14 s. Compared with the expert manual Simpson, limits of agreement for novice corrected AutoEF was lower than for novice manual Simpson (0.8 +/- 10.5 vs. -3.2 +/- 11.4 LVEF percentage points). Calculated for experts and with LVEF (%) categorized into < 30, 30-44, 45-54 and > or = 55, kappa measure of agreement was moderate (0.44-0.53) for all method comparisons (uncorrected AutoEF not evaluated).

CONCLUSION

Corrected AutoEF reduces the variation in measurements compared with manual planimetry, without increasing the time required. The method seems especially suited for unexperienced readers.