ESTRO 2024 - Abstract Book

S5010

Physics - Radiomics, functional and biological imaging and outcome prediction

ESTRO 2024

θ=0-90 ϕ =90-180 Block 3 θ=-0 - -90 ϕ =90-180 Block 4 θ=0 - -90 ϕ =0-90 Block 5 θ=90-180 ϕ =0-90 Block 6 θ=90-180 ϕ =90-180 Block 7 θ=-90 - -180 ϕ =90-180 Block 8 θ=-90 - -180 ϕ =0-90

Posterior, inferior, right

Posterior, inferior, left

Anterior, superior, left

Anterior, superior, right

Anterior, inferior, right

Anterior, inferior, left

Table 1. Regional blocks by SCS

For each patient, the volume of each regional block was tracked from S1 and S2. Spearman’s coefficient (ρ) was calculated to assess the consistency of block volume ranking from S1 to S2, and correlated against WTV, ADC and R2*.

Results:

Median ADC and R2* increased from S1 to S2 for WTV (p<0.05). Analysis using SCS showed overall increase in median ADC and R2* within regional blocks, although the magnitude of increase varied between the blocks.

ρ was positively correlated against absolute WTV at S1 (0.69) and S2 (0.75), indicating more consistent block rankings with larger tumours. There was no significant correlation with ρ and percentage change in WTV, ADC or R2* from S1 to S2. Only two patients demonstrated residual disease after completing treatment, allowing for identification of potential AOI. One of these patients had residual disease in the left cervix. For this patient, regions were dichotomised by laterality. Blocks 1,4,5 and 8 (left of tumour) demonstrated significantly lower ADC than the right at S1 and S2, lower increases in ADC across treatment, higher R2* and higher change in R2* across treatment (p<0.05). Figure 2. demonstrates a WTV heatmap for S2 ADC/R2*, demonstrating the AOI on the tumour posterior-left which exhibited features of persistent hypercellularity (low ADC, low increase in ADC) and increasing hypoxia (higher R2*).