Imaging of Solid Tumors Using 18F-TRX

This imaging study is using a new radioactive tracer called 18F-TRX in a PET scan to detect and visualize solid tumors more precisely — including brain tumors, kidney cancer, and prostate cancer — to see how well it works compared to standard imaging. **You may be eligible if...** - You are 18 or older - You have an advanced solid tumor, specifically: any solid tumor with at least 3 metastases, OR a high-grade brain tumor (glioma), OR clear cell kidney cancer with metastases, OR castration-resistant prostate cancer - Your performance status is good (ECOG 0–1) - You have adequate blood counts and organ function **You may NOT be eligible if...** - You are pregnant or breastfeeding - You have received recent radiation to areas being imaged - Your cancer type is not one of the included groups Talk to your doctor to see if this trial is right for you.