A multicentre and multi-national evaluation of the accuracy of quantitative Lu-177 SPECT/CT imaging performed within the MRTDosimetry project

Research output: Contribution to journalArticlepeer-review

Authors

  • Johannes Tran-Gia
  • Ana M. Denis-Bacelar
  • Kelley M. Ferreira
  • Andrew P. Robinson
  • Nicholas Calvert
  • Andrew J. Fenwick
  • Domenico Finocchiaro
  • Federica Fioroni
  • Elisa Grassi
  • Warda Heetun
  • Stephanie J. Jewitt
  • Maria Kotzassarlidou
  • Michael Ljungberg
  • Daniel R. McGowan
  • Nathaniel Scott
  • James Scuffham
  • Katarina Sjögreen Gleisner
  • Jill Tipping
  • Jill Wevrett
  • Michael Lassmann

Institutes & Expert groups

  • University of Würzburg - Institute for Molecular Infection Biology
  • Christie Medical Physics and Engineering, The Christie NHS Foundation, Manchester
  • NPL - National Physical Laboratory
  • University of Bologna
  • UNIMORE - University of Modena and Reggio Emilioa - DIEF - department of Engineering "Enzo Ferrari"
  • Churchill Hospital
  • Theagenio Cancer hospital of Thessaloniki
  • Lund University

Documents & links

Abstract

Purpose: Patient-specific dosimetry is required to ensure the safety of molecular radiotherapy and to predict response. Dosimetry involves several steps, the first of which is the determination of the activity of the radiopharmaceutical taken up by an organ/lesion over time. As uncertainties propagate along each of the subsequent steps (integration of the time–activity curve, absorbed dose calculation), establishing a reliable activity quantification is essential. The MRTDosimetry project was a European initiative to bring together expertise in metrology and nuclear medicine research, with one main goal of standardizing quantitative 177Lu SPECT/CT imaging based on a calibration protocol developed and tested in a multicentre intercomparison. This study presents the setup and results of this comparison exercise. Methods: The inter-comparison included nine SPECT/CT systems. Each site performed a set of three measurements with the same setup (system, acquisition and reconstruction): (1) Determination of an image calibration for conversion from counts to activity concentration (large cylinder phantom), (2) determination of recovery coefficients for partial volume correction (IEC NEMA PET body phantom with sphere inserts), (3) validation of the established quantitative imaging setup using a 3D printed two-organ phantom (ICRP110-based kidney and spleen). In contrast to previous efforts, traceability of the activity measurement was required for each participant, and all participants were asked to calculate uncertainties for their SPECT-based activities. Results: Similar combinations of imaging system and reconstruction lead to similar image calibration factors. The activity ratio results of the anthropomorphic phantom validation demonstrate significant harmonization of quantitative imaging performance between the sites with all sites falling within one standard deviation of the mean values for all inserts. Activity recovery was underestimated for total kidney, spleen, and kidney cortex, while it was overestimated for the medulla. Conclusion: This international comparison exercise demonstrates that harmonization of quantitative SPECT/CT is feasible when following very specific instructions of a dedicated calibration protocol, as developed within the MRTDosimetry project. While quantitative imaging performance demonstrates significant harmonization, an over and underestimation of the activity recovery highlights the limitations of any partial volume correction in the presence of spill-in and spill-out between two adjacent volumes of interests.

Details

Original languageEnglish
Pages (from-to)1-17
Number of pages17
JournalEJNMMI Physics
Volume8
DOIs
Publication statusPublished - 23 Jul 2021

Keywords

  • Quantitative SPECT/CT, 177Lu SPECT/CT imaging, Standardization of SPECT/CT imaging, Harmonization of SPECT/CT imaging, International multicenter comparison exercise, Traceability of SPECT/CT imaging, Molecular radiotherapy (MRT), 3D printing, Phantom

ID: 7401013