Cross-camera comparison of ROI-based semi-quantitative 123 I-IBZM SPECT data in healthy volunteers using an anthropomorphic phantom for calibration

Abstract

Background

In ¹²³I-Iolopride (IBZM) SPECT reference values may diverge between camera systems. If multicenter pooling of normal material databases is needed, differences in measured semi-quantitative data due to equipment performance and reconstruction parameters have to be investigated in each instance to determine the comparability.

Purpose

To explore the differences in ¹²³I-IBZM measured uptake ratios between two different gamma cameras in healthy controls, the intra-rater reproducibility of the image evaluation method and the possibility to equalize uptake ratios by calibration through an anthropomorphic phantom.

Material and Methods

Differences in ROI-based semi-quantitative data from two different gamma camera systems, the three-headed brain dedicated Neurocam and the two-headed multipurpose hybrid system Infinia Hawkeye, were studied using image data from a group of healthy volunteers and an anthropomorphic brain-phantom scanned with both cameras. Several reconstruction methods and corrections were applied. To test the reliability of the ROI method, the intra-observer reproducibility was determined for the ROI method in this study.

Results

The ROI method had a high reliability. Differences in mean measured uptake ¹²³I-IBZM ratios in healthy controls varied between 2.9% and 6.5% depending on reconstruction and correction for attenuation and scatter. After calibration, the differences decreased. There were no statistically significant differences between corrected ratios from the two camera systems in the study when images were reconstructed with attenuation correction.

Conclusion

The conformity of uptake ratios in attenuation corrected ¹²³I-IBZM images derived from the two different cameras was improved by using an anthropomorphic phantom for calibration.