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- Title
Biodistribution and dosimetry for combined [<sup>177</sup>Lu]Lu-PSMA-I&T/[<sup>225</sup>Ac]Ac-PSMA-I&T therapy using multi-isotope quantitative SPECT imaging.
- Authors
Delker, Astrid; Schleske, Mirjam; Liubchenko, Grigory; Berg, Isabella; Zacherl, Mathias Johannes; Brendel, Matthias; Gildehaus, Franz Josef; Rumiantcev, Mikhail; Resch, Sandra; Hürkamp, Kerstin; Wenter, Vera; Unterrainer, Lena M.; Bartenstein, Peter; Ziegler, Sibylle I.; Beyer, Leonie; Böning, Guido
- Abstract
Purpose: Quantitative SPECT for patient-specific dosimetry is a valuable tool in the scope of radionuclide therapy, although its clinical application for 225Ac-based treatments may be limited due to low therapeutic activities. Therefore, the aim of this study was to demonstrate the feasibility of clinical quantitative low-count SPECT imaging during [177Lu]Lu-PSMA-I&T/[225Ac]Ac-PSMA-I&T treatment. Methods: Eight prostate cancer patients (1000 MBq/8 MBq [177Lu]Lu-PSMA-I&T/[225Ac]Ac-PSMA-I&T) received a single-bed quantitative 177Lu/225Ac SPECT/CT acquisition (1 h) at 24 h post treatment (high-energy collimator, 16 projections p. head à 3.5 min, 128 × 128 pixel). The gamma peak at 440 keV (width: 10%) of the progeny 213Bi was imaged along with the peak at 208 keV (width: 15%) of 177Lu. Quantification included CT-based attenuation and window-based scatter correction plus resolution modelling. Gaussian post-filtering with a full-width-half-maximum of 30 mm and 40–45 mm was employed to match the signal-to-noise ratio of 225Ac and 177Lu, respectively. Results: Kidney (r = 0.96, p < 0.01) and lesion (r = 0.94, p < 0.01) SUV for [177Lu]Lu-PSMA-I&T and [225Ac]Ac-PSMA-I&T showed a strong and significant correlation. Kidney SUV were significantly higher (p < 0.01) for [225Ac]Ac-PSMA-I&T (2.5 ± 0.8 vs. 2.1 ± 0.9), while for [177Lu]Lu-PSMA-I&T lesion SUV were significantly higher (p = 0.03; 1.8 ± 1.1 vs. 2.1 ± 1.5). For absorbed dose estimates, significant differences regarding the kidneys remained, while no significant differences for lesion dosimetry were found. Conclusion: Quantitative low-count SPECT imaging of the peak at 440 keV during [225Ac]Ac-PSMA-I&T therapy is feasible. Multi-isotope imaging for [177Lu]Lu-PSMA-I&T/[225Ac]Ac-PSMA-I&T therapy indicates accumulation of free 213Bi in the kidneys.
- Subjects
POSITRON emission tomography computed tomography; PROSTATE cancer patients; RADIOLIGAND assay; COLLIMATORS; GAUSSIAN distribution
- Publication
European Journal of Nuclear Medicine & Molecular Imaging, 2023, Vol 50, Issue 5, p1280
- ISSN
1619-7070
- Publication type
Article
- DOI
10.1007/s00259-022-06092-1