ESTRO 2024 - Abstract Book

S5154

Physics - Radiomics, functional and biological imaging and outcome prediction

ESTRO 2024

3107

Digital Poster

MRI reveals a strong association between severe hypoxia and the metastatic cascade in PCa patients

Knut Håkon Hole 1 , Therese Seierstad 1 , Heidi Lyng 2 , Tord Hompland 2

1 Oslo University Hospital, Department of Radiology, Oslo, Norway. 2 Oslo University Hospital, Institute of Cancer Research, Oslo, Norway

Purpose/Objective:

Tumor hypoxia limits the effect of radiation therapy (RT) and is associated with poor outcome after RT in prostate cancer (PC) patients. However, a lack of feasible methods for its assessment limits biological studies and makes an introduction of tumor hypoxia in treatment planning unattainable. We have previously biologically validated a MR imaging tool for quantifying and visualizing hypoxia in PC patients, termed Consumption and Supply based Hypoxia (CSH) imaging (1). Recently we have demonstrated that CSH can provide information on different hypoxia levels (severe to mild) and here we aim to confirm this result in PC patients and study the biology associated with different hypoxia levels.

Material/Methods:

106 patients received a multi b-value diffusion weighted (DW) MR prior to prostatectomy. By using a simplified IVIM model, parameter maps related to cell density, ADC and vascular density, fBV, were extracted. These images, representing oxygen consumption and supply, were combined on a pixel-by-pixel basis to create CSH maps representing hypoxia levels (1). From the surgical specimens, pathological parameters like, Longest axis, Gleason score (GS), T stage (pT), lymph node metastasis (LN) and lymphovascular invasion(LVI) was determined. From pathological parameters we could obtain information that relates to the metastatic cascade: pT, LVI, and LN represents local invasion, intravasation and extravasation respectively. In addition, the presence of comedo necrosis was examined. Outcome to prostatectomy was defined by PSA relapse.

Results:

Comedo necrosis can be regarded as a morphological end stage of hypoxia, and its presence was used as a biological estimate of severe hypoxia. In line with our hypothesis, the lower signal intensities of CSH imaging were strongly associated with the presence of comedo necrosis (p<0.0001). We have previously demonstrated by pimonidazole staining that CSH imaging can measure moderate hypoxia. These results demonstrate that different levels of hypoxia can be measured by CSH imaging in PC patients, and we utilized CSH images to study the associations between different hypoxia levels and parameters obtained from pathology.