New hybrid count- and geometry-based method for quantification of left ventricular volumes and ejection fraction from ECG-gated SPECT: Methodology and validation

doi:10.1016/j.nuclcard.2004.09.015

Journal of Nuclear Cardiology

Volume 12, Issue 1, January–February 2005, Pages 55-65

Presented in part at the Institute of Electrical and Electronic Engineers Nuclear Science Symposium and Medical Imaging Conference, Portland, Oregon, October 19–25, 2003.

https://doi.org/10.1016/j.nuclcard.2004.09.015 Get rights and content

Background

We have previously developed a new method for quantitative assessment of left ventricular (LV) volumes and ejection fraction (EF) from electrocardiography-gated single photon emission computed tomography (SPECT). The aims of this study were to present the methodology, to validate the gated SPECT cardiac quantification (GSCQ) method in phantoms and patients, and to determine normal values of LVEF.

Methods and results

A simple thresholding technique was used to generate binary images from nongated SPECT images. The K-means cluster classification algorithm was used to separate the LV region from non-LV regions on the binary images. A count- and geometry-based algorithm was applied to define endocardial and epicardial boundaries for calculation of LV volumes and LVEF. Overall correlation between GSCQ-quantified volumes and actual phantom volumes was good (r = 0.97 and standard error of estimation (SEE) = 9.99 mL for normal phantoms, r = 0.99 and SEE = 6.97 mL for phantoms with defects). In patient studies, LVEF derived by GSCQ from SPECT and from equilibrium radionuclide angiography also showed good correlation (r = 0.90 and SEE = 6.2%). The lower limit of normal LVEF from 8-frame gated SPECT by use of GSCQ was 45%. Quantification of LVEF by the GSCQ method was highly producible and was not significantly affected by the presence of myocardial perfusion defects or intense gastrointestinal activity.

Conclusions

The GSCQ method provides reliable and consistent assessments of LV volumes and EF. This methodology is less affected by intense gastrointestinal activity than other methods.

Section snippets

Definition of LV region and exclusion of background on nongated horizontal long-axis slice

The GSCQ method starts with the identification of a central nongated horizontal long-axis slice (Figure 1A)—that is, the slice with maximal LV cavity diameter. An initial binary image was generated from the central horizontal long-axis slice by use of a simple thresholding scheme, in which the 50% maximal intensity obtained from the upper half of nongated short-axis images was used as a cutoff.² The K-means cluster classification algorithm¹⁴ was adapted to divide the initial binary image into 2

Normal phantoms

Figure 4A shows the correlation between quantified SPECT volumes and actual volumes for normal phantoms (r = 0.97). Figure 4B shows the Bland-Altman plot and limits of agreement. There was overestimation in large phantom volumes and underestimation in small volumes. The mean difference for normal phantoms was −1.67 mL.

Phantoms with defect inserts

Figure 4C shows the correlation between quantified volumes and actual phantom volumes for phantoms with defect inserts. The correlation with actual volumes was slightly better (r

Discussion

We have presented the methodology of GSCQ for quantifying LV volumes and LVEF from gated SPECT imaging. The method was based on a combination of count density information and geometry of the left ventricle. Endocardial and epicardial boundaries of the LV myocardium were detected with incorporation of an integrated count strategy. LV volumes and LVEF were calculated based on mathematically derived endocardial boundaries. GSCQ was validated in phantoms and in patients. The GSCQ method showed good

Acknowledgment

We thank Oleg Drozhinin, MD, for an initial drawing of the phantom design; Enrique Vallejo, MD, Peter Lam, MD, Mary Jo Zito, and Vera Tsatkin for data collection and technical assistance; and Barry L. Zaret, MD, for reviewing the manuscript. Through an arrangement with Yale University School of Medicine (New Haven, Conn), Drs Liu, Sinusas, and Wackers receive royalties from the sale of Wackers-Liu CQ software.

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Citation Excerpt :
Infarct size, the LV ejection fraction (LVEF), and cardiac volumes were determined from the reconstructed SPECT images by core laboratory (Yale University Radionuclide Core Laboratory, New Haven, Connecticut) using Wackers-Liu CQ software (GE Healthcare, Waukesha, Wisconsin).7 Myocardial perfusion defects (infarct size) were quantified and expressed as a percentage of the left ventricle relative to a normal reference database, and the LVEF was determined using a validated method.7,8 Standard image acquisition was performed at all clinical sites and submitted to an independent angiographic core laboratory.
Elevated leukocyte count during ST-segment elevation myocardial infarction is associated with adverse clinical outcomes. Whether increased leukocyte count after primary percutaneous coronary intervention (PCI) directly reflects larger infarct size and left ventricular impairment is not known. The aim of this study was to assess the relation between leukocyte and neutrophil counts with infarct size and the left ventricular ejection fraction (LVEF) after primary PCI. Three hundred sixty-three patients from the Evaluation of MCC-135 for Left Ventricular Salvage in Acute Myocardial Infarction (EVOLVE) study, a randomized, double-blind, placebo-controlled trial assessing the efficacy of intracellular calcium modulator as an adjunct to primary PCI in patients with first ST-segment elevation myocardial infarctions, were evaluated. Total and differential leukocyte counts were measured before and serially after PCI. Infarct size and the LVEF were assessed using single-photon emission computed tomography after 5 and 30 days, and patients were followed up to 180 days. Total leukocyte and neutrophil counts obtained 24 hours after PCI were significantly correlated with infarct size (r = 0.34 and 0.37, respectively, p <0.001) and inversely correlated with the LVEF (r = −0.20 and −0.22, respectively, p <0.001). Patients with elevated leukocyte and neutrophil counts had larger infarct sizes (12.5% vs 5% and 13.5% vs 5%, respectively, p <0.001). The highest neutrophil quartile was associated with increased 180-day composite cardiac events (19% vs 20% vs 23% vs 45%, log-rank p <0.001). Elevated leukocyte and neutrophil counts independently predicted adverse cardiac events (hazard ratios 2.5 and 2.2, respectively, p = 0.001). In conclusion, elevated leukocyte and neutrophil counts after primary PCI in patients with ST-segment elevation myocardial infarctions are directly related to myocardial infarct size and the LVEF and are independent predictors of cardiovascular outcomes.

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: This study was funded in part by Eclipse Systems Inc, Branford, Conn, and GE Medical Systems, Waukesha, Wis.

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Original articlesNew hybrid count- and geometry-based method for quantification of left ventricular volumes and ejection fraction from ECG-gated SPECT: Methodology and validation

Background

Methods and results

Conclusions

Section snippets

Definition of LV region and exclusion of background on nongated horizontal long-axis slice

Normal phantoms

Phantoms with defect inserts

Discussion

Acknowledgment

J Nucl Cardiol

J Nucl Cardiol

J Nucl Cardiol

J Nucl Cardiol

J Nucl Cardiol

J Nucl Cardiol

Left ventricular ejection fraction assessed from gated technetium-99m-sestamibi SPECT

J Nucl Med

Automatic quantification of ejection fraction from gated myocardial perfusion SPECT

J Nucl Med

Reproducibility of 3-D MSPECT for quantitative gated SPECT sestamibi perfusion analysis

J Nucl Med

Original articles
New hybrid count- and geometry-based method for quantification of left ventricular volumes and ejection fraction from ECG-gated SPECT: Methodology and validation