[Coronary flow reserve index corrected by exercise load using Tl-201 SPECT: evaluation by PTCA]

Area of Science:

• Cardiology
• Nuclear Medicine
• Medical Imaging

Background:

• Coronary artery disease assessment requires reliable methods for evaluating coronary flow reserve.
• Non-invasive techniques are preferred for patient comfort and safety during diagnostic procedures.

Purpose of the Study:

• To investigate a novel coronary flow reserve index (CRI) using Thallium-201 SPECT during exercise.
• To evaluate the correlation between myocardial fractional distribution changes and myocardial oxygen demand.
• To assess the utility of CRI in patients with effort angina pectoris and its changes after percutaneous coronary intervention (PTCA).

Main Methods:

• Utilized single photon emission computed tomography (SPECT) with Thallium-201 (Tl-201) using a double dose method.
• Performed SPECT at submaximal exercise and rest in 24 patients with effort angina and 11 healthy volunteers.
• Calculated the coronary reserve index (CRI) as the ratio of change in myocardial fractional distribution (delta-Fract) to the change in pressure-rate product (delta-PRP).

Main Results:

• A strong correlation was found between delta-Fract and delta-PRP during exercise and rest.
• The calculated CRI demonstrated a good correlation with the coronary flow reserve index.
• CRI in ischemic regions correlated with percent area stenosis and improved after PTCA, though not always reaching normal ranges.

Conclusions:

• Exercise SPECT using the double dose method provides a useful, non-invasive estimation of coronary flow reserve.
• The developed coronary reserve index (CRI) is valuable for assessing coronary blood flow during exercise.
• CRI can effectively evaluate the impact of interventions like PTCA on coronary flow reserve.