Assessing myocardial flow reserve using CZT SPECT perfusion imaging: a step towards clinical application

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Abstract Background Maximal hyperemia capacity and myocardial flow reserve (MFR) have emerged as critical indicators of cardiovascular prognosis, with reduced vascular functionality associated with adverse outcomes (1). PET-CT serves as the gold standard for MFR assessment in clinical practice. In recent years, SPECT equipment with high-performance CZT detectors has been utilized for quantitative assessment of coronary flow at rest and under maximal hyperemia. The potential of MFR in guiding clinical decision-making for coronary artery disease (CAD) management is increasingly recognized. However, the clinical feasibility and utility of CZT-derived MFR data remains under active investigation. Objective This study aims to describe the feasibility of quantitatively measuring myocardial flow reserve obtained using SPECT equipment with CZT detectors in patients undergoing scintigraphy to assess coronary disease. Methodology One hundred patients with suspected or known CAD underwent pharmacological stress myocardial perfusion scintigraphy (adenosine) and rest imaging using a D-SPECT device (Spectrum Dynamics) between October 7th, 2021, and December 30th, 2022. Dynamic tomographic images were acquired with the administration of 99mTc-sestamibi via an injection pump (Bracco) at a flow rate of 1 ml/second. Cedars Sinai's QPS kinetic software was used to calculate MFR, with values < 2 considered abnormal. Statistical analysis was performed using a significance level of 5% and the Student's T-type comparison test. Results Twenty patients (71 men), with a mean age of 69.4 years, were evaluated. Thirteen exams presented global MFR < 2, with an additional 11 patients showing global MFR > 2 and regional MFR in any of the three coronary territories below 2. Notably, six patients with MFR < 2 did not demonstrate abnormal myocardial perfusion imaging in SPECT. Patients with MFR values < 2 had a lower mean left ventricular ejection fraction compared to those with MFR > 2 (52% vs. 62%; p = 0.02). All exams were of good quality and interpretable. Motion correction was required in most exams (>90%). In two patients, the radiotracer and adenosine were administered through external jugular venous access due to unavailability of venous access in the cubital fossa. Conclusion Myocardial flow reserve (MFR) assessment can be effectively conducted using SPECT equipment equipped with CZT detectors, enabling the identification of patients with diminished MFR both globally and within specific coronary territories. These findings provide valuable insights into the management of patients with suspected or confirmed coronary artery disease (CAD). However, further investigation is warranted to elucidate the precise clinical implications of MFR assessment with CZT SPECT in guiding management strategies for patients with CAD.

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