The non-invasive assessment of resting left ventricular (LV) performance is an integral part of the evaluation of patients with known or suspected cardiac disease, having important diagnostic, therapeutic, and prognostic significance.1–11 Although scintigraphic measures of cardiac function historically included measurement of ejection fraction (EF), estimation of cardiac output and valvular regurgitant fraction and detection of intracardiac shunts have also been performed. Other than EF, these potential applications for nuclear cardiology techniques have been largely supplanted by echocardiography, cardiac computed tomography, and magnetic resonance imaging (MRI) techniques over the past two decades.
Gated equilibrium radionuclide angiography (ERNA, often called multiple-gated acquisition [MUGA] and equilibrium radionuclide ventriculography [RNV]) was introduced nearly 30 years ago. It was routinely utilized in the evaluation of patients with known or suspected LV dysfunction, post-myocardial infarction (MI), and valvular disease, and for monitoring the cardiotoxic effects of chemotherapeutic drugs. Exercise radionuclide angiography (RNA), particularly with the first-pass radionuclide angiographic (FPRNA) technique, was widely used to diagnose or evaluate known coronary artery disease (CAD),5–9 competing favorably with and often complementing planar myocardial perfusion imaging (MPI). However, since its introduction, RNA has evolved little, while other non-invasive methods, such as gated single photon emission computed tomography (SPECT) MPI, echocardiography, and cardiac magnetic resonance, have been introduced and become increasingly sophisticated and cost effective.
First-pass Radionuclide Angiography
If ERNA is to be performed in addition to FPRNA, after placement of a large-bore (14- or 16-gauge) antecubital intravenous line, 1.5 mg of stannous pyrophosphate is mixed with 30 mL of the patient's blood for approximately 60 s, and is then reinfused. Resting FPRNA is usually performed after a 10-min delay to allow further red blood cell uptake of stannous ion. Technetium 99m (Tc-99m) pertechnetate (25–30 mCi) in a volume of <1 mL is then flushed rapidly with at least 30 mL of normal saline through the indwelling catheter. This can be followed within a few minutes by planar and/or tomographic (SPECT) ERNA images. For FPRNA, Tc-99m DTPA is often used if no equilibrium images are required. Perfusion agents, such as Tc-99m sestamibi or tetrofosmin, may be utilized if perfusion images are desired.12–14
FPRNA images are usually obtained using a single- or multicrystal high-count rate gamma camera fitted with a high-sensitivity parallel hole collimator (e.g., SIM 400, Scinticor, Milwaukee, Wis; or ElGems CardiaL [formerly Elscint], Haifa, Israel). Images are acquired in the anterior or the right anterior oblique (RAO) projection using 25 (±4) frames per cardiac cycle. Preliminary work suggests that FPRNA can also be performed with positron emission tomography (PET) using images acquired during a bolus of radiolabeled water (H215O), but this has not yet achieved widespread utilization or validation.15
FPRNA data are analyzed using the frame method for LVEF using commercially available computer software,16–18 as shown in Figs. 10-1,10-2, 10-3. This software creates a representative LV volume curve by summing frames of several (usually 5–10) cardiac cycles, which are aligned by matching their end diastoles (histogram peaks) and end systoles (histogram valleys) during the operator-defined levophase of radioactive tracer transit. The pulmonary-frame background-corrected representative cycle is then examined with a fixed region ...