Real time ultrasound molecular imaging of prostate cancer with PSMA-targeted nanobubbles.

Contrast-enhanced ultrasound with microbubbles has shown promise in detection of prostate cancer (PCa), but sensitivity and specificity remain challenging. Targeted nanoscale-contrast agents with improved capability to accumulate in tumors may result in prolonged signal enhancement and improved detection of PCa with ultrasound. Here we report nanobubbles (NB) that specifically targets prostate specific membrane antigen (PSMA) overexpressed in PCa. The PSMA-targeted-NB (PSMA-NB) were utilized to simultaneously image dual-flank PCa (PSMA-positive PC3pip and PSMA-negative PC3flu) to examine whether the biomarker can be successfully detected and imaged in a mouse model. Results demonstrate that active targeting rapidly and selectively enhances tumor accumulation and tumor retention. Importantly, these processes could be visualized and quantified, in real-time, with clinical ultrasound. Such demonstration of the immense yet underutilized potential of ultrasound in the molecular imaging area can open the door to future opportunities for improving sensitivity and specificity of cancer detection using parametric NB-enhanced ultrasound imaging.