Comparison of the diagnostic yield of various systematic randomized prostate biopsy protocols using prostate phantoms made of devil's tongue jelly

PURPOSE: The purpose of this study was to compare the diagnostic yield of five systematic randomized protocols using 12-20 biopsy cores with variably-sized phantoms. METHODS: A total of 100 prostate phantom models were produced by casting liquid devil’s tongue jelly using silicone molds. Sets of 20 phantoms were created with the following volumes: 20 mL, 40 mL, 60 mL, 80 mL, and 100 mL. Three focal lesions were created by injecting 0.5 mL of warm agar solution stained with red, blue, and green ink into each phantom model. The focal lesions were verified by ultrasonography. The systematic randomized biopsy protocols consisted of 12, 14, 16, 18, and 20 biopsy cores. The diagnostic yield of the multiple systematic biopsy protocols was compared. RESULTS: The overall detection rates of each model set were 93.3% for 20 mL, 88.3% for 40 mL, 71.7% for 60 mL, 43.3% for 80 mL, and 30.0% for 100 mL. Statistically significant differences in the detection rate were found between 40 mL and 60 mL and between 60 mL and 80 mL. No statistically significant increase in the detection rate was observed within a given volume set even when the number of core biopsies increased from 12 to 20. CONCLUSION: The diagnostic yield of systematic randomized biopsies is inversely proportional to the phantom volume.