Highlights
- Dynamic 4D SPECT imaging of ¹⁷⁷Lu-Trastuzumab from 3 to 53 min post injection
- 5-min frame duration, including 3 min of effective acquisition per frame
- Static 3D SPECT imaging at 120 min, 24 h, 48 h and 120 h post injection, using acquisition durations from 9 to 30 min
- Low-activity 3D SPECT visualization with activity during imaging down to 1.13 MBq
Introduction
Preclinical assessment of ¹⁷⁷Lu-labelled radiopharmaceuticals may require imaging across very different temporal and activity conditions, from the first minutes after administration to delayed time points when less activity remains available for imaging.
This application demonstrates dynamic 4D SPECT and static 3D SPECT imaging of ¹⁷⁷Lu-Trastuzumab using the BIOEMTECH γ-eye™ system. Imaging was performed in a SKOV-3 xenograft model, combining early time-resolved imaging, static acquisitions at multiple post-injection time points and a separate lower-activity assessment.
Study design
¹⁷⁷Lu-Trastuzumab was evaluated in a SKOV-3 xenograft model using the γ-eye™ system.
For the dynamic proof-of-concept acquisition, SPECT imaging was performed from 3 to 53 min post injection, with 40.2 MBq of activity during imaging. The effective acquisition time was 3 min per frame, with a total frame duration of 5 min including detector repositioning.
Static SPECT imaging was performed at 120 min, 24 h, 48 h and 120 h post injection. Activity during imaging was 30.0, 25.4, 22.5 and 13.8 MBq, respectively. At each time point, images were evaluated using acquisition durations of 9, 12, 18 and 30 min.
An additional lower-activity assessment included 30-min static acquisitions with activity during imaging ranging from 1.13 to 2.66 MBq.
Results
Dynamic SPECT imaging
Sequential SPECT frames provided time-resolved whole-body visualization throughout the early post-injection period, from 3 to 53 min post injection.
Figure 1: Dynamic SPECT imaging of ¹⁷⁷Lu-Trastuzumab in a SKOV-3 xenograft model from 3 to 53 min post injection. Activity during imaging: 40.2 MBq. Effective acquisition time: 3 min per frame. Total frame duration: 5 min, including detector repositioning.
Static SPECT imaging across multiple time points
Static SPECT images were acquired at all four evaluated time points, extending the assessment from 120 min to 120 h post injection. The representative 30-min acquisitions shown below illustrate radiopharmaceutical distribution as activity during imaging decreased from 30.0 to 13.8 MBq.
Figure 2: Representative 30-min static SPECT images of ¹⁷⁷Lu-Trastuzumab acquired at 120 min, 24 h, 48 h and 120 h post injection. Activity during imaging: 30.0, 25.4, 22.5 and 13.8 MBq, respectively.
Low-activity SPECT imaging
Thirty-minute static acquisitions also provided SPECT visualization under substantially lower-activity conditions, with activity during imaging down to 1.13 MBq.
Figure 3: Static SPECT image of ¹⁷⁷Lu-Trastuzumab in a SKOV-3 xenograft model at 120 h post injection. Activity during imaging: 1.13 MBq. Acquisition duration: 30 min.
Conclusion
By combining early dynamic SPECT, static imaging at multiple post-injection time points and lower-activity acquisitions, the γ-eye™ system provides a flexible workflow for preclinical imaging of ¹⁷⁷Lu-labelled radiopharmaceuticals across a broad temporal and activity range.
This application demonstrates how acquisition duration can be adapted to the activity available at each imaging time point while preserving the spatial assessment provided by SPECT.