Evaluation of left ventricular function using a semiconductor gamma camera and a fast low-dose protocol

Introduction. - New gamma camera technology with Cadmium-Zinc-Telluride (CZT) semiconductor detectors provides better myocardial perfusion imaging (MPI) resolution and, given the detector's high-sensitivity (better spatial and energy resolution), it reduces imaging time and radiopharmaceutical doses (better detection sensitivity). The purpose of this study was to evaluate the left ventricular function parameters obtained by a fast low-dose clinical protocol on a CZT camera (D-SPECT), compared to the measurement on cardiac magnetic resonance imaging. Methods. - We retrospectively included patients who underwent MPI on D-SPECT camera with a low-dose of Sestamibi-^99mTc (120 MBq for stress and 360 MBq at rest for a patient of 75 kg weight), and a cardiac magnetic resonance imaging, with a time less than two months. The left ventricular function was obtained at rest, with 8-frame reformatted, and analysis was performed using Quantitative Gated SPECT (QGS1) software. Results. - Seventy-seven patients were included and their mean ejection fraction (EF) was 45±13% at MRI. For D-SPECT recording, mean activity within heart area was 527±104 kcps, for mean recording time 3.5±2.2 min and mean of the total activity was 420±185 MBq (effective dose: 3.7±1.6 mSv). Correlation between D-SPECT and MRI was very good for EF (r = 0.88), end-diastolic volume (EDV, r = 0.90) and end-systolic volume (ESV, r = 0.96), but with an underestimation of all these parameters by the D-SPECT (on average, 5% absolute value for EF, and -16% and -24% in relative values for respectively ESV and EDV). Conclusion. - The evaluation of left ventricular function using the D-SPECT camera and with a fast low-dose protocol correlates well with that obtained by cardiac MRI, in the same patient. EF and ventricular volumes are however underestimated, in agreement with that previously documented with conventional Anger cameras. (authors)