Gated right ventricular studies using krypton-81m: comparison with first-pass studies using gold-195m.

Area of Science:

• Nuclear medicine
• Cardiovascular imaging
• Radiopharmaceutical applications

Background:

• Equilibrium ECG-gated imaging with krypton-81m (81mKr) is established for right ventricular function assessment.
• First-pass radionuclide angiography is another method for evaluating right ventricular ejection fraction (RVEF).

Purpose of the Study:

• To compare the accuracy of RVEF calculations using gated 81mKr imaging versus first-pass 195mAu imaging.
• To evaluate the impact of analysis methods (variable vs. fixed regions of interest) and background correction on RVEF measurements.

Main Methods:

• Continuous i.v. infusion of 81mKr for equilibrium gated studies.
• First-pass studies using 195mAu.
• Analysis of RVEF using both variable and fixed regions of interest (ROIs).
• Comparison of results with and without background correction.

Main Results:

• Variable ROIs yielded significantly higher RVEF than fixed ROIs in 81mKr studies, irrespective of background correction.
• Significant differences in RVEF were observed between first-pass and gated studies without background correction (p < 0.01).
• No significant differences were found between the two methods when background correction was applied.

Conclusions:

• RVEF calculations are subject to significant systematic errors influenced by the chosen analysis method.
• Background correction is essential for accurate comparison of RVEF measurements obtained by different radionuclide techniques.
• Gated 81mKr imaging, with appropriate background correction and analysis, provides reliable RVEF assessment.