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Advances in Radiotherapy
& Nuclear Medicine LuPSMA response patterns on PSMA PET

A A

B
B

Figure 4. (A-C) Differences in PSMA expression in “responders” and C
“progressors.” Patient A is a “responder,” showing a homogeneous
reduction in PSMA intensity. Patient B is a “progressor,” with persistently
high and heterogeneous PSMA expression.
Abbreviation: PSMA: Prostate-specific membrane antigen.

3.6. TLW analysis reproducibility
A hierarchical linear mixed model was utilized to assess the
repeatability of the TLW. All participants were included,
encompassing a total of 228 lesions. There was no evidence
of a systematic difference between test and retest for
SUV , SUV mean , or lesional tumor volume. Lesion type
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(reducing, stable, or increasing) had an expected effect Figure 5. (A-C) The TLW identifies patterns of disease progression:
on SUV , SUV mean , and tumor volume (p<0.001 for all). Patient A had low PSMA expression progressive disease. Patient B had
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persistently high PSMA expression disease progression. Patient C had
The repeatability estimate for SUV was 0.96 (95%CI, oligo-progression, with a treatment response at most sites of disease but
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0.94–0.97), for SUV mean was 0.97 (95%CI; 0.96–0.98), for two new bony metastases(red arrows).
lesion volume was 0.96 (95%CI, 0.94–0.97), and for TLW Abbreviations: PSMA: Prostate-specific membrane antigen; TLW: Traffic
response category was 0.93 (95%CI, 0.87–0.97) (Table 4). light workflow.
4. Discussion treatment-resistant lesions and has the potential to impact
The TLW was developed to evaluate treatment response therapeutic decision-making. The workflow showed good
at a lesional level, incorporating measurement of lesion repeatability and has potential for automation in the future,
volume and PSMA avidity. We hypothesized that allowing for easy integration into current clinical practice.
TLW would enable quantitative characterization of Previous work from the LuPIN trial identified that
heterogeneous treatment responses. This work is the first PSMA intensity declined in 95% of participants following
to monitor tumor responses in individual lesions and 177 Lu-PSMA-617 therapy. Therefore, we defined a
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classify an overall response pattern for each participant. “responding” lesion as one showing a reduction in lesion
TLW facilitates identification and characterization of volume with a stable or decreasing SUV . Progressive
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Volume 3 Issue 3 (2025) 49 doi: 10.36922/ARNM025110011