Optimized Needle Biopsy Strategies for Prostate Cancer Detection

Clinical diagnosis of prostate cancer is most often done by transrectal ultrasound-guided needle biopsy. Because of the low resolution of ultrasound, however, the urologist cannot usually distinguish between cancerous and healthy tissue. Therefore, most biopsies follow standard procedures (known as “protocols”) based on long-term physician experience. Recent studies indicate that these protocols may have a significant rate of false negative diagnoses. This research develops optimized biopsy protocols. We use real prostate specimens removed by prostatectomy to develop a 3D distribution map of cancer in the prostate. We develop also a probability model of the needle insertion procedure. Using this model, the tumor map, and the geometry of the biopsy needle, we obtain estimates for the probability of obtaining a positive biopsy in various zones of prostates with cancer. Using this we develop a nonlinear optimization problem that determines the protocols that maximize the probability of cancer detection for a given number of needles, and present new optimized protocols.