Tissue dose estimation after extravasation of 177Lu-DOTATATE

Perrine Tylski; Géraldine Pina-Jomir; Claire Bournaud-Salinas; Patrice Jalade

doi:10.1186/s40658-021-00378-3

Tissue dose estimation after extravasation of ¹⁷⁷Lu-DOTATATE

EJNMMI Phys. 2021 Mar 31;8(1):33. doi: 10.1186/s40658-021-00378-3.

Authors

Perrine Tylski¹, Géraldine Pina-Jomir², Claire Bournaud-Salinas², Patrice Jalade³

Affiliations

¹ Service de Physique Médicale et Radioprotection, Hospices Civils de Lyon, Lyon, France. perrine.tylski@chu-lyon.fr.
² Service de Médecine Nucléaire, Groupement Hospitalier Est, Hospices Civils de Lyon, Lyon, France.
³ Service de Physique Médicale et Radioprotection, Hospices Civils de Lyon, Lyon, France.

Abstract

Background: Extravasation of radiopharmaceuticals used for vectorized internal radiotherapy can lead to severe tissue damage (van der Pol et al., Eur J Nucl Med Mol Imaging 44:1234-1243, 2017). Clinical management of these extravasations requires the preliminary estimation of the dose distribution in the extravasation area. Data are scarce regarding the dose estimation in the literature. This work presents a methodology for estimating the dose distribution after an extravasation occurred in September 2017, in the arm of a patient during a 7.4-GBq infusion of Lutathera ® (AAA).

Methods: A local quantification procedure initially developed for renal dosimetry was used. A calibration factor was determined and verified by phantom study. Extravasation volume of interest and its variation in time were determined using 4 whole body (WB) planar acquisitions performed at 2 h (T_2h), 5 h (T_5h), 20 h (T_20h), and 26 h (T_26h) after the beginning of the infusion and three SPECT/CT thoracic acquisitions at T_5h, T_20h, and T_26h. For better estimation of initial extravasation volume, 3 volumes were defined on SPECT images using a 3D activity threshold. Cumulated activities and associated absorbed doses (D₁, D₂, D₃) were calculated in the 3 volumes using the MIRD formalism.

Results: Volumes estimated using 3D threshold were V₁ = 1000 mL, V₂ =400 mL, and V₃ =180 mL. Cumulated activities were evaluated using a monoexponential fit on activities calculated on SPECT images. Estimated local absorbed doses in V₁, V₂, and V₃ were D₁ = 2.3 Gy, D₂ = 4.1 Gy, and D₃ = 6.8 Gy. Evolution in time of local activity in the extravasation area was consistent with an effective local half-life (T_eff) of 2.3 h.

Conclusions: Rapid local dose estimation was permitted thanks to knowledge of the calibration factor determined previous to accidental extravasation. Lutathera® lymphatic drainage was quick in the arm (T_eff = 2.3h). Estimated doses were in the lower range of deterministic effects and far under soft tissue necrosis threshold. Thus, no surgical rinse was proposed. The patient did not show any clinical consequence of the extravasation.

Keywords: 177Lu-DOTATATE; Dosimetry; Extravasation.