The ability to measure myocardial blood flow reserve (MBFR) non-invasively with the new digital solid-state cadmium zinc telluride (CZT) cardio -gamma-camera

Abstract Introduction Myocardial Blood Flow Reserve (MBFR) has been proposed as an important functional indicator of the severity of coronary artery disease (CAD) following the pioneering studies of Gould and his colleagues in the 1970s. MBF at rest remains normal until vessel diameter stenosis reaches 80–85%, while under hyperemia it begins to progressively decrease when stenosis exceeds 40%. In recent years, the advent of fully digital gamma-camera systems has made possible measurements that were previously considered unattainable. One such measurement is MBFR, achieved through dynamic myocardial imaging, coronary blood flow measurement, and stenosis percentage calculation. Until recently, MBFR calculation was performed only using PET-CT systems with the use of isotopes such as 82Rb, 13N, and Oxygen-15 labelled water. In Greece, cardiac PET-CT examinations are not conducted, and therefore non-invasive diagnostic MBFR assessments are not available. The CZT gamma-camera represents the latest technological advancement in nuclear medicine and is the system of choice in major hospitals worldwide. The Onassis Hospital (OH) is the first hospital in Greece equipped with DSPECT- Cardio by Spectrum Dynamics CZT gamma-camera. It is characterized by high system sensitivity. Purpose The aim of this study was to evaluate the outcomes of dynamic studies using CZT-SPECT (Single Photon Emission Computed Tomography) of myocardial blood flow reserve (MBFR) for the early detection of coronary artery disease (CAD), its clinical risk, and its correlation with invasive coronary angiography. Methods 250 patients (200 men and 50 women) underwent dynamic imaging, in accordance with ASNC guidelines. All patients first underwent a resting dynamic study using Tc-99m sestamibi, followed one hour later by a hyperemic dynamic study after administration of regadenoson, with continuous ECG monitoring and blood pressure measurement. Perfusion and functional images (Gated SPECT MPI) of the myocardium were also obtained both at rest and after pharmacologic stress with regadenoson. All patients underwent coronary angiography within three months of the scintigraphic study. Results 220 out of the 250 studies (80%) were of satisfactory quality and technically sound. There was a very good correlation with coronary angiography stenosis index. The sensitivity of MBFR SPECT was 83.3% for stenosis above 80%. Conclusion Non-invasive measurement of MBFR is now feasible with very satisfactory correlation with coronary angiography. The inclusion of MBFR in SPECT MPI for CAD evaluation using CZT cameras may help identify high-risk patients and improve diagnostic performance—contributing both to prevention and to the reduction of false-negative MPI results. MBFR could assist cardiologists in deciding whether to proceed with coronary angiography. A larger patient sample, optimization of the technique for improved sensitivity, and communication of the method to clinical physicians are needed.