Quantitative comparison of pre-therapy 99mTc-macroaggregated albumin SPECT/CT and post-therapy PET/MR studies of patients who have received intra-arterial radioembolization therapy with 90Y microspheres

Publication date: Available online 21 October 2018

Source: European Journal of Radiology

Author(s): Karin Knešaurek, Abbas Tuli, Sara D Pasik, Sherif Heiba, Lale Kostakoglu

Abstract

Objective

The aim of our study was to compare yttrium -90 (⁹⁰Y) dosimetry obtained from pre-therapy ^99mTc- macroaggregated albumin (MAA) SPECT/CT versus post-therapy PET/MRI imaging among patients with primary or metastatic hepatic tumors.

Materials and methods

Prior to ⁹⁰Y radioembolization (RE), 32 patients underwent a scan using MAA mimicking ⁹⁰Y distribution. After RE with ⁹⁰Y microspheres, the patients were imaged on a PET/MRI system. Reconstructed images were transferred to a common platform and used to calculate ⁹⁰Y dosimetry. The Passing- Bablok regression scatter diagram and the Bland and Altman method were used to analyze the difference between dosimetry values.

Results

For MAA and PET/MRI modalities, the mean liver doses for all 32 subjects were 43.0 ± 20.9 Gy and 46.5 ± 22.7 Gy, respectively, with a mean difference of 3.4 ± 6.2 Gy. The repeatibility coefficient was 12.1 (27.0% of the mean). The Spearman rank correlation coefficient was high (ρ = 0.92). Although, there was a substantial difference in the maximum doses to the liver between the modalities, the mean liver doses were relatively close, with a difference of 24.0 % or less.

Conclusions

The two main contributors to the difference between dosimetry calculations using MAA versus ⁹⁰Y PET/MRI can be attributed to the changes in catheter positioning as well as the liver ROIs used for the calculations. In spite of these differences, our results demonstrate that the dosimetry values obtained from pre-therapy MAA SPECT/CT scans and PET/MRI post-therapy ⁹⁰Y studies were not significantly different.

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