Comparison between N13NH3-PET and99mTc-Tetrofosmin-CZT SPECT in the evaluation of absolute myocardial blood flow and flow reserve

Background PET/CT is the standard for quantitative assessments of myocardial blood flow (MBF), but it requires short-lived-tracers, costly, and not widely available. SPECT with Cadmium Zinc Telluride (CZT) detectors allows dynamic acquisition and quantitation of MBF. The study aims were to compare MBF measurements by(99m)Tc-tetrofosmin-CZT to (NNH3PET)-N-13/CT after regadenoson-induced coronary hyperemia and to evaluate the effect of attenuation correction (AC). Methods 54 patients were evaluated at rest and during vasodilation by(99m)Tc-tetrofosmin-CZT and (NNH3PET)-N-13/CT within 2 weeks. MBF and MBF reserve (MFR) were measured by CZT with or without AC (NAC). Results The global rest MBF was 0.76 +/- 0.19 mL/min/gr by PET and 0.76 +/- 0.24 by AC-CZT (P = NS) and 1.14 +/- 0.4 by NAC-CZT (P< 0.001 vs PET and AC-CZT). Stress MBF was higher when measured by PET than AC-CZT (1.87 +/- 0.45 vs 1.62 +/- 0.68 mL/min/gr,P< 0.0008), but lower than NAC-CZT (2.36 +/- 1.1,P< 0.0003). The MBF reserve ratio (MFR) was higher by PET than AC-CZT (2.52 +/- 0.56 vs 2.22 +/- 1 (P< 0.009) and NAC-CZT (2.18 +/- 1.0,P< 0.004). Linear regression was better between PET (MFR and stress MBF) and AC-CZT than between PET and NAC-CZT. ROC curve analysis showed the significant ability of AC-CZT to predict MFR < 2 and stress MBF < 1.7 (AUC = 0.75 and 0.82 respectively) and to differentiate between normal and CAD patients (AUC = 0.747 and 0.892 for MFR and stress MBF, respectively). Conclusions Our data show a reasonable correlation between MBF and MFR measured by (NNH3)-N-13-PET and(99m)Tc-Tetrofosmin-CZT SPECT. NAC-CZT overestimates MBF. AC is recommended when using CZT for measuring MBF.

Automated summary

This study compared MBF measurements using different imaging techniques and found that CZT may overestimate MBF. Attenuation correction is recommended when using CZT for MBF measurements to ensure accurate results.