Description:
Noninvasive methods for coronary flow reserve (CFR) assessment would be attractive for both clinical and investigative purposes. We validated a method to estimate CFR with single-photon emission computed tomography (SPECT) tracers to obtain data for quantitative functional assessment of coronary artery disease (CAD) (J Nucl Cardiol 2004 and 2008). The prosecution of this activity has been focused on the clinical applications of this approach. We evaluated the influence of risk factors on CFR in patients with one-vessel CAD and demonstrated that the number of coronary risk factors influences CFR (J Nucl Med 2005). We also showed that the impairment of endothelium-dependent vasodilatation can be demonstrated in patients with peripheral artery disease and compromised CFR is related to the degree of peripheral artery dysfunction (J Nucl Med 2005). In patients with new discovered never treated hypertension, we demonstrated that cardiac hypertrophy is associated with endothelial dysfunction while maximal dipyridamole-dependent CFR may be preserved (J Hum Hypert 2005). In diabetic patients without stenoses on coronary angiography, quantitative estimates of rest myocardial perfusion were comparable to those in age-matched control subjects (J Nucl Cardiol 2007). However, when myocardial perfusion was assessed in a similar fashion during dipyridamole-induced hyperemia, patients had lower measures of hyperemic flow, as well as CFR. In another study, we demonstrated that in patients with typical chest pain, positive exercise stress test and normal coronary vessels, impaired CFR may sustain ischemic-related symptoms (Eur J Nucl Med Mol Imaging 2007). Noteworthy, estimated myocardial blood flow at rest was lower in age-matched controls compared to patients, while stress blood flow was not different between controls and patients. Consequently, estimated CFR was higher in controls compared to patients. More recently, we compared two different methods for the estimation of CFR by SPECT imaging (Eur J Nucl Med Mol Imaging 2009). Myocardial blood flow (MBF) was estimated by measurement of first transit counts in the right pulmonary artery (PA) and left ventricular (LV) chamber. The results showed that SPECT estimated CFR obtained using first transit counts from right PA is more accurate and correlates better with the results of intracoronary Doppler than estimated CFR obtained using arterial input function from LV chamber