Quantification of intramyocardial blood volume using ^99mTc-RBC SPECT/CT: a pilot human study

Area of Science:

• Cardiovascular Imaging
• Nuclear Medicine
• Medical Physics

Background:

• Intramyocardial blood volume (IMBV) quantification is a key indicator for assessing myocardial microcirculatory function.
• Previous large animal studies successfully validated SPECT/CT with 99mTc-labeled Red Blood Cell (RBC) for accurate IMBV measurement.
• This study presents the first-in-human pilot data and processing methods for IMBV quantification.

Purpose of the Study:

• To evaluate the feasibility of quantifying intramyocardial blood volume (IMBV) in human subjects using SPECT/CT.
• To assess IMBV under both resting and adenosine-induced stress conditions.
• To report the data processing techniques and initial results from a human pilot study.

Main Methods:

• SPECT/CT imaging with 99mTc-RBC was performed on three subjects at rest and during stress.
• Data processing included corrections for attenuation, scatter, respiratory/cardiac motion, and partial volume effects.
• An automated segmentation and registration approach based on blood pool topology was employed for image analysis.

Main Results:

• Resting end-diastolic IMBV was 35.0% ± 3.3%, and end-systolic IMBV was 24.1% ± 2.7%.
• Stress end-diastolic IMBV was 40.6% ± 4.2%, and end-systolic IMBV was 26.5% ± 2.8%.
• The cycle-dependent change in IMBV (ΔIMBV) was 31.5% ± 3.0% at rest and 34.7% ± 7.4% under stress.

Conclusions:

• Quantification of IMBV using SPECT/CT with 99mTc-RBC is feasible in human subjects.
• The method allows for the measurement of myocardial blood volume changes under both resting and stress states.
• This technique shows promise for evaluating microcirculatory function in clinical settings.