Inter- and Intraobserver Repeatability of Myocardial Flow Reserve Values Determined with SPECT Study Using a...

Area of Science:

• Cardiology
• Nuclear Medicine
• Medical Imaging

Background:

• Myocardial blood flow (MBF) and flow reserve (MFR) are crucial for diagnosing multivessel coronary artery disease (CAD).
• Cadmium-zinc-telluride (CZT) SPECT offers an alternative to Positron Emission Tomography (PET) for MBF/MFR assessment.
• Current processing methods for CZT SPECT studies involve subjective factors impacting accuracy.

Purpose of the Study:

• To evaluate the intra- and interobserver repeatability of MBF and MFR values derived from CZT SPECT imaging.
• To identify potential sources of variability in MBF and MFR measurements.
• To compare the diagnostic utility of CZT SPECT with PET for specific coronary territories.

Main Methods:

• Fifty-seven adult patients underwent MBF and MFR assessment using a CZT SPECT gamma camera (Discovery NM530c) with 99mTc-MIBI.
• A two-day rest/dipyridamole protocol was employed.
• Data were processed using Corridor4DM software, with assessments performed twice by one operator and once by a second independent operator.

Main Results:

• Repeatability of MBF and MFR values was found to be good across the whole myocardium, as well as in the left anterior descending (LAD) and left circumflex (LCX) vascular territories.
• A poor degree of repeatability was observed specifically within the right coronary artery (RCA) vascular territory.
• The findings suggest variability in measurement consistency depending on the coronary artery assessed.

Conclusions:

• Poor repeatability in the RCA territory may stem from issues with automatic heart axis orientation and cardiac creep during post-processing.
• Improvements in automatic heart orientation and motion correction algorithms are anticipated to enhance measurement repeatability.
• For MFR assessment in the RCA territory, PET imaging may currently be a more reliable option than CZT SPECT, given software limitations.