Proper intra-tumoral distribution of radiopharmaceutical is crucial for successful targeted alpha therapy (TAT) with [225Ac]Ac-DOTA-SP (Substance P), due to a short range of alpha particles in tissue. We demonstrate the first convection-enhanced local delivery of [225Ac]Ac-DOTA-SP, in vivo confirmed by [68Ga]Ga-DOTA-SP PET/CT and quantitative SPECT/CT.
A 54-year-old female with a recurrence of glioblastoma (G4,IDH-) was referred for locoregional treatment with [225Ac]Ac-DOTA-SP. In an MRI scan (A1,A2) performed 1 week before TAT, the postoperative cavity volume was 12.6 cm3 and the volume of contrast-enhanced tissue adjacent to the cavity was 4.2 cm3 (total lesion volume 16.8 cm3). The [ 225Ac]Ac-DOTA-SP activity equal to 18.8 MBq was co-injected with 10 MBq of [ 68Ga]Ga-DOTA-SP into the postoperative cavity. The first PET/CT (B1,B2) was acquired 15 min post-injection. Next, a 2 hours slow infusion (10 µl/min) of saline was performed using a syringe pump. The second PET/CT (C1,C2) was acquired 3 h post-injection. Additionally, quantitative SPECT/CT imaging (D1,D2) was performed 5 days post-injection (20% energy windows centered over the two photopeaks: 440 and 218 keV, plus 10% lower and upper windows for scatter correction, 128x128 matrix, 128 projections, 30 s per projection, reconstruction and calibration method described.).
Two PET/CT images showed homogenous uptake with increased functional volume (from initial 12.6 cm3 to 17.7 cm3 measured 3 h postinjection, threshold 10%). The quantitative SPECT/CT image revealed stable uptake after 5 days. Taken into account 225Ac physical decay, activity calculated based on SPECT/CT image on the time of injection was equal to 20.1 MBq.
TULIK Monika;
PAWLAK Dariusz;
KULINSKI Radoslaw;
BRUCHERTSEIFER Frank;
KUNERT Przemyslaw;
KROLICKI Leszek;
MORGENSTERN Alfred;
KUNIKOWSKA Jolanta;
2026-05-04
SPRINGER
JRC143496
1619-7089 (online),
https://link.springer.com/article/10.1007/s00259-025-07527-1,
https://publications.jrc.ec.europa.eu/repository/handle/JRC143496,
10.1007/s00259-025-07527-1 (online),
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