Imaging and Diagnostic Testing
Gated single-photon emission computed tomographic myocardial imaging: A new tool in clinical cardiology

https://doi.org/10.1067/mhj.2001.112780Get rights and content

Abstract

Background Gated single-photon emission computed tomography (gated SPECT) myocardial perfusion imaging allows the analysis of left ventricular (LV) perfusion and function during the same acquisition. Results Gated SPECT provides additional information to myocardial perfusion, which improves test specificity in patients with known or suspected coronary artery disease and hence diminishes the amount of borderline diagnosis. Because gated SPECT provides reliable information on LV ejection fraction and LV volumes, it is also a valuable tool in risk stratification. In addition, from gated SPECT, images can be reconstructed from which wall motion can be assessed showing a good correlation with wall motion assessed by accepted imaging modalities as echocardiography, magnetic resonance imaging, and contrast angiography. In the future wall motion analysis from gated SPECT may also be used for revascularization stratification. Conclusions Gated SPECT gives important additional information beyond myocardial perfusion imaging alone, which could have major clinical implications for optimal patient management. (Am Heart J 2001;141:383-90.)

Section snippets

Gated SPECT techniques

Various techniques have been reported to derive information on LV function from gated myocardial perfusion studies.3, 4, 5, 6 Measurements of LV function from gated SPECT are often implemented by fully exploiting the three-dimensional nature of the tomographic datasets. The LV endocardial surface and valve planes are estimated in three-dimensional space, followed by summation of the volumes of the voxels bound by these structures. Techniques for the identification of the endocardial surface

Thallium- or 99mTc-labeled agents?

Because of the high count density of the 99mTc-labeled agents compared with 201Tl, it is preferable to use 99mTc-labeled agents when functional information with gated SPECT is mandatory, especially if a multidetector camera is not available. Yet several studies have investigated the reliability of functional information obtained by use of gated SPECT with 201Tl. These studies showed a good correlation of calculated EF between gated SPECT with 201Tl and gated SPECT with 99mTc sestamibi.9, 10

Gated SPECT imaging validation by other methods

Several studies have compared functional information on the LV between gated SPECT and other well-known imaging modalities such as magnetic resonance imaging (MRI), contrast angiography, echocardiography, gated blood pool imaging, and first-pass studies (Table I).7, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20

. Correlations of LV functions among different accepted imaging modalities and gated SPECT

TechniqueNo. of patientsLVEF correlationLVEDV correlationLVESV correlationLVWM (κ, exact agreement)
First

Functional information of LV derived by gated SPECT at rest versus (30 minutes) after stress

The acquisition of the stress gated SPECT myocardial perfusion image with use of 99mTc-labeled agents is started at least 30 minutes after stress, indicating that the functional information represents the functional status at 30 minutes after stress. In healthy subjects the LV function 30 minutes after stress will be similar to LV function at rest. However, it is possible that, in patients with coronary artery disease (CAD) after stress, LV dysfunction and transient cavity dilatation may

Additional value of gated SPECT myocardial perfusion imaging

Patients with suspected CAD and a normal perfusion are known to have a <1% change of a coronary event in the near future.26, 27 Conversely, patients with perfusion defects on the SPECT myocardial perfusion image have a relatively high incidence of coronary events at follow-up.28

On myocardial perfusion images showing a persistent perfusion defect, a clear-cut diagnosis is not always possible. This phenomenon may occur in patients with suspected CAD in the absence of a known previously sustained

Identification of artifacts caused by left bundle branch block

Left bundle branch block (LBBB) can be caused by myocardial infarction, heart surgery, hypertension, aortic valve problems, or cardiomyopathies. For optimal patient management it is important to know whether there is additional reversible ischemia. In these patients an ergometer electrocardiogram (ECG) is never conclusive because of the LBBB pattern on the rest ECG, which renders the interpretation of the stress ECG difficult. Myocardial perfusion scintigraphy has a high false-positive rate for

Detection of viability

Several methods have been established to differentiate patients with myocardial viability from patients without viable myocardium. These methods include (1) 201Tl imaging to assess myocardial perfusion and cell membrane integrity, (2) dobutamine echocardiography to assess myocardial contractile reserve, and (3) F-18-fluorodeoxyglucose positron emission tomography (18FDG-PET) imaging to assess the myocardial metabolic state.38, 39, 40 Nicolai et al41 showed a good correlation between 201Tl

Prognostic value of gated SPECT myocardial perfusion imaging

Numerous studies in the past have shown the prognostic value of myocardial perfusion imaging.27 However, it has also been shown that resting or exercise LVEF determined by radionuclide angiography is a major determinant of long-term survival in patients with CAD.48 Other studies show an even higher incremental prognostic value of LVESV. White et al49 showed that ESV had greater predictive value for survival than did EDV or LVEF. In a recent study by Sharir et al,50 1680 patients were analyzed

General conclusions

Gated SPECT allows us to analyze LV perfusion and function during the same acquisition. Gating provides a valuable adjunct to 99mTc-sestamibi or tetrofosmin SPECT in characterizing perfusion abnormalities and potentially improving test specificity. Gated SPECT is a valuable tool in risk stratification because it provides information of LV ESV and LVEF, which are both important prognostic parameters and have incremental value over perfusion alone. Gated SPECT imaging may be used for

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    Reprint requests: Ernst E. van der Wall, MD, Department of Cardiology, C5-P28, Leiden University Medical Center, Albinusdreef 2, 2333 AZ, Leiden, The Netherlands. E-mail: [email protected]

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