CZT SPECT accurately quantifies ejection fraction

While myocardial perfusion imaging (MPI) using cadmium-zinc-telluride (CZT) SPECT cameras accurately measures left ventricular ejection fraction (LVEF), the method underestimates left ventricular volumes, according to a study published online Feb. 5 in the Journal of Nuclear Medicine.

Recently developed CZT detectors offer higher count sensitivity, new camera geometry and new reconstruction algorithms, which may modify SPECT performance for analyzing LV global and regional function.

Hubert Cochet, MD, from the department of cardiovascular imaging at Hopital cadiologique in Passac, France, and colleagues sought to evaluate the accuracy of MPI SPECT for measurement of LV global and regional function and the performance of absolute wall motion and wall thickness measurements, using cardiac MR as a reference.

The researchers enrolled 60 patients with known or suspected coronary artery disease referred for routine SPECT from October 2010 to May 2011.

The correlation between SPECT and cardiac MR was good for end diastolic volume and excellent for end systolic volume and EF. On regional measures, correlation between SPECT and MRI was fair for both wall motion and wall thickness.

A total of 16 patients were found to have moderate or severe perfusion defects. Bias between the two exams for measurement of end systolic volume was greater among patients with moderate-to-severe defects than in patients with no defects, according to Cochet and colleagues.

“Studying 60 patients with a representative range of LV dysfunction, we demonstrated that quantification of EF using quantitative-gated SPECT analysis is accurate, although it still underestimates ventricular volumes,” wrote Cochet et al.

Previous studies have indicated that MPI SPECT underestimates EF, and CZT may be more accurate. However, CZT SPECT tends to underestimate ventricular volumes, which is likely related to how SPECT datasets define the aortic and mitral planes, according to the researchers.

“Gated MPI SPECT using CZT cameras and quantitative-gated SPECT analysis is highly accurate for the quantification of EF. However, a significant underestimation of LV volumes persists,” concluded Cochet and colleagues.