Assessment of diastolic function using 16-frame 201Tl gated myocardial perfusion SPECT: a comparative study of QGS2 and pFAST2

Clinical usefulness of a novel program "Heart Function View" for evaluating cardiac function from gated myocardial perfusion SPECT

OBJECTIVE

To investigate clinical usefulness of a novel program "Heart Function View (HFV)" for evaluating left ventricular (LV) function from myocardial perfusion SPECT (MPS), we compared LV functional parameters (F(x)) calculated by HFV with those obtained by the other similar programs QGS and cardioGRAF or by ultrasound echocardiography (UCG) and examined their correlations with clinical markers of heart failure: plasma BNP concentrations (BNPs) and exercise capacity.

METHODS

Studied patients (n = 60) underwent technetium-99m tetrofosmin quantitative gated MPS including treadmill exercise for examining heart disease. Myocardial stress images were acquired 30 min after the first tracer injection during maximal exercise. Three hours later, the second tracer was injected, and resting images were acquired. LV systolic F(x) [ejection fraction (EF), peak ejection rate (PER)] and diastolic F(x) [first third filling fraction (1/3FF), first third filling rate (1/3FR), peak filling rate (PFR), time to PFR (TPF)] were analyzed, and phase standard deviation (SD) and histogram bandwidth were obtained by phase analysis.

RESULTS

LV end-diastolic volume (EDV), end-systolic volume (ESV) and EF obtained from HFV were well correlated with those from QGS, cardioGRAF and UCG. A diastolic parameter Doppler E/e' from UCG was significantly with PFR from HFV. There were good correlations between LVEDV, LVESV, LVEF, PER, PFR, 1/3FR, TPF and 1/3FF from HFV and those from cardioGRAF. LVEF, PER, 1/3FR, and PFR were significantly correlated with plasma BNP concentrations. In patients with non-ischemic heart disease (n = 42), phase SD and histogram bandwidth were correlated negatively with exercise capacity or PFR.

CONCLUSIONS

HFV-derived LVF(x) are correlated with LVF(x) from the other programs or UCG, or with the clinical markers of heart failure and are thus useful in the functional assessment for patients with heart disease.

[Analysis of the diastolic function by myocardial perfusion gated SPECT after coronary revascularization in acute myocardial infarction]

OBJECTIVE

To evaluate the evolutive changes in diastolic function after percutaneous coronary revascularization (PCR) in acute myocardial infarction (AMI), using myocardial perfusion gated SPECT.

METHODS

Thirty-two patients (mean 61.9±9.7 years, 7 women) were studied by two at rest gated SPECT: the first gated-SPECT-1 was performed with an injection of a dose of (99m)Tc-tetrofosmin prior to PCR and the second gated-SPECT-2 between the fourth and fifth weeks after AMI. Changes of peak filling rate (PFR) and the time to peak filling rate (TTPF) were assessed between both studies, and were related to the extent of salvaged myocardium (SM), end-diastolic (EDV) and end-systolic (ESV) volumes, and left ventricular ejection fraction (LVEF) changes.

RESULTS

An improvement was observed in diastolic function parameters Gated-SPECT-2: PFR increased significantly (P=0.011) while the TTPF decreased without reaching statistical significance (P=0.288). In multivariate analysis, adjusted by clinical and coronary variables, improvement of PFR was significantly associated with percentage of SM (P=0.030), increase in LVEF (P=0.004) and with ESV volume reduction (P=0.005). Improvement of TTPF was only related significantly to the percentage of SM (P=0.046). PFR increased 0.01 EDV/sec. and TTPF decreased 1.14ms for each cm(2) increase of the area of SM.

CONCLUSIONS

After PCR in AMI, the myocardial perfusion gated SPECT makes it possible to assess the significant improvement in diastolic function mainly related to the amount of MS.

Clinical use of nuclear cardiology in the assessment of heart failure

A nuclear cardiology test is the most commonly performed non-invasive cardiac imaging test in patients with heart failure, and it plays a pivotal role in their assessment and management. Quantitative gated single positron emission computed tomography (QGS) is used to assess quantitatively cardiac volume, left ventricular ejection fraction (LVEF), stroke volume, and cardiac diastolic function. Resting and stress myocardial perfusion imaging, with exercise or pharmacologic stress, plays a fundamental role in distinguishing ischemic from non-ischemic etiology of heart failure, and in demonstrating myocardial viability. Diastolic heart failure also termed as heart failure with a preserved LVEF is readily identified by nuclear cardiology techniques and can accurately be estimated by peak filling rate (PFR) and time to PFR. Movement of the left ventricle can also be readily assessed by QGS, with newer techniques such as three-dimensional, wall thickening evaluation aiding its assessment. Myocardial perfusion imaging is also commonly used to identify candidates for implantable cardiac defibrillator and cardiac resynchronization therapies. Neurotransmitter imaging using (123)I-metaiodobenzylguanidine offers prognostic information in patients with heart failure. Metabolism and function in the heart are closely related, and energy substrate metabolism is a potential target of medical therapies to improve cardiac function in patients with heart failure. Cardiac metabolic imaging using (123)I-15-(p-iodophenyl)3-R, S-methylpentadecacoic acid is a commonly used tracer in clinical studies to diagnose metabolic heart failure. Nuclear cardiology tests, including neurotransmitter imaging and metabolic imaging, are now easily preformed with new tracers to refine heart failure diagnosis. Nuclear cardiology studies contribute significantly to guiding management decisions for identifying cardiac risk in patients with heart failure.