ESTRO 2024 - Abstract Book

S5119

Physics - Radiomics, functional and biological imaging and outcome prediction

ESTRO 2024

= agreement between analyses, False Negative = significant DVH result in a structure outside the VBA significant volume (at the 80% significance level).

Results:

Meaningful declines in working memory and processing speed were observed in 18(22%) and 17(18%) patients respectively. VBA identified a region of the frontal lobe as correlated with decline in processing speed. This is concordant with what was observed in (3). VBA analyses also revealed a strong association between working memory decline and radiation dose to a small sub-volume of the brainstem (Figure 1). In contrast, DVH analysis revealed no significant association between the brainstem and decline in working memory (likely because of the small size of the significant region within the brainstem) but identified an association with dose to the right hippocampus. Taking the DVH analysis as gold standard (Table 1), VBA achieved a sensitivity of 72.7%, and specificity and precision of 100%. Population DVHs reveal a greater difference in dose delivered to the significant region between children experiencing and not experiencing cognitive decline, compared to dose to the whole brainstem (Figure 2).

DVH Analysis

Positives

Negatives Total

Positives

8

0

8

VBA

Negatives 3

1

4

Total

11

1

12

Table 1. Confusion matrix comparing conclusions from VBA and DVH analyses. DVH “positive” and “negative” results represent published p-values (3). VBA “positive” and “negative” results reflect the presence or absence, respectively, of significant-volume overlap with the anatomic structure of interest. In any dose distribution, doses to neighbouring structures are highly correlated to each other. While VBA methods consider the full 3D dose distribution, DVH analyses consider each structure independently: weaker associations may appear positive in DVH analyses, while stronger associations exist with other (for example, neighbouring) structures. This scenario would appear as a “VBA negative”/ “DVH positive”, e.g. right hippocampus and working memory. Association between dose to left hippocampus and working memory was “VBA negative”/ “DVH negative”.