Impact of Single-Time-Point Estimates of 177Lu-PRRT Absorbed Doses on Patient Management: Validation of a Trained Multiple-Linear-Regression Model in 159 Patients and 477 Therapy Cycles

Alexandre Chicheportiche, Moshe Sason, Mahmoud Zidan, Jeremy Godefroy, Yodphat Krausz, David J. Gross, Simona Grozinsky-Glasberg, Simona Ben-Haim

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Dosimetry after 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) enables estimation of radiation doses absorbed by normal organs and target lesions. This process is time-consuming and requires multiple posttreatment studies on several subsequent days. In a previous study, we described a newly developed multiple-linear-regression model to predict absorbed doses (ADs) from a single-time-point (STP) posttreatment study acquired 168 h after the first infusion and 24 h after the following ones, with similar results to the standard multiple-time-point (MTP) protocol. The present study aimed to validate this model in a large patient cohort and to assess whether STP dosimetry affects patient management decisions compared with our MTP protocol. Methods: Quantitative 177Lu-DOTATATE SPECT/CT post-PRRT data from 159 consecutive patients (172 therapies, 477 therapy cycles) were retrospectively analyzed. ADs obtained from an STP model were compared with those obtained using an MTP model. We evaluated the impact of the STP model on the decision on whether PRRT should be stopped because of an expected kidney AD exceeding the safety threshold. We hypothesized that patient management based on the STP model does not differ from that based on the MTP model in at least 90% of the cases. Results: There was no difference in management decisions between the MTP and STP models in 170 of 172 therapies (98.8%). A Fisher x2 test for combined probabilities produced a composite P value of 0.0003. Mean cumulative AD relative differences between the STP and MTP models were 0.8% 6 8.0%, 27.7% 6 4.8%, 0.0% 6 11.4%, 22.8% 6 6.3%, and 22.1% 6 18.4% for kidneys, bone marrow, liver, spleen, and tumors, respectively (Pearson r 5 0.99 for all), for patients who underwent 4 therapy cycles. Similar results were obtained with fewer therapy cycles. Conclusion: Estimated radiation ADs and patient management decisions were similar with the STP and MTP models. The STP model can simplify the dosimetry process while also reducing scanner and staff time and improving patient comfort.

Original languageEnglish
Pages (from-to)1610-1616
Number of pages7
JournalJournal of Nuclear Medicine
Volume64
Issue number10
DOIs
StatePublished - Oct 2023
Externally publishedYes

Bibliographical note

Publisher Copyright:
COPYRIGHT © 2023 by the Society of Nuclear Medicine and Molecular Imaging.

Keywords

  • Lu-DOTATATE
  • PRRT
  • SPECT/CT
  • internal dosimetry
  • peptide receptor radionuclide therapy
  • single time point

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