Comparison of global and regional myocardial blood flow quantification using dynamic solid-state detector SPECT and Tc-99 m-sestamibi or Tc-99 m-tetrofosmin in a routine clinical setting

Solid-state detector single photon emission computed tomography (SPECT) enables the acquisition of dynamic data for calculation of myocardial blood flow (MBF) and myocardial flow reserve (MFR). Here, we report about our experiences on routine clinical use and robustness using Tc-99 m-sestamibi and Tc-99 m-tetrofosmin. 307 patients underwent dynamic list-mode myocardial perfusion imaging (MPI) and standard static MPI for clinical workup of coronary artery disease on a dedicated cardiac SPECT camera. After exclusion of 33 scans, 274 scans were eligible for MBF and MFR calculation using a 1-tissue-compartment model. Attenuation correction was performed for all patients using an external computed tomogram. Patients underwent stress-only scans, both stress and rest scans or rest-only scans using Tc-99 m-tetrofosmin or Tc-99 m-sestamibi. 30 patients without known cardiovascular comorbidities and without perfusion defect on static scans were compared in a sub analysis. Global stress myocardial blood flow (MBF) was significantly higher than rest MBF (2.3 vs. 1.1 ml/min/g; p < 0.001), and showed a high variability among individuals. Global myocardial flow reserve (MFR) was 2.1 (range 0.5-7.8). An analysis of 30 patients without known cardiovascular comorbidities yielded similar stress MBF measures for Tc-99 m-sestamibi and Tc-99 m-tetrofosmin (3.1 ± 1.2 vs. 2.8 ± 0.9 ml/min/g; p = 0.429). The use of attenuation correction lead to systematically lower MBF measures. Patients who underwent a one-day protocol had notably higher rest MBF (1.2 ± 0.5 vs. 1.0 ± 0.46 ml/min/g; p = 0.009) and consequently a lower MFR. Summed defect scores from standard static scans and presence of cardiovascular comorbidities negatively impacted MBF and MFR. Quantitative SPECT MBF and MFR in a clinical routine setting yields flow measures in range of expectation at an albeit wide range and is comprehensibly linked with results from standard static scan and patients history of cardiovascular diseases. Use of one-day protocols and attenuation correction systematically alters quantitative results. However, SPECT-derived MBF and MFR lack clinical reliability due to less validated reference ranges and high inter-individual variability.