1Department of Radiology, Samsung Cheil Hospital and Samsung Seoul Hospital, Sungkyunkwan University School of Medicine, Korea. 2Department of Radiology, Seoul National University College of Medicine and the Institute of Radiation Mdeicine, SNUMRC, Korea. kimsh@radcom.snu.ac.kr
Published online: March 1, 2002.
ABSTRACT
PURPOSE: To evaluate of the accuracy and usefulness of direct TRUS-guided prostatic biopsy by performing multi-ple random biopsies of prostate models with a focal lesion. MATERIALS AND METHODS: One hundred prostate models was made and shaped using devil 's tongue jelly by cutting the surface. In those prostate models, a focal lesion was created by an injection of warm agar solution that was stained with blue ink. To evaluate the accuracy of direct TRUS-guided prostatic biopsy according to the size of the lesion and the distance from the surface, 180 models were divided into 6 groups (three groups with the focal lesion with the volume of 0.02 cc, 0.1 cc and 0.5 cc within 1 cm from the posterior surface of the models, and the other three groups with the same volumes of the focal lesion but at the distance of 1.5 cm). Direct biopsies were performed for three times in each model. The success rates of directed biopsies in the three groups were compared. To compare the diagnosis rate of multiple systematic biopsy of the prostate, 4, 6 and 8 times of random biopsies were performed in the first thirty models with a 0.1 cc lesion (clinically insignificant lesion) and another 30 models with a 0.5 cc lesion, and the results were compared. RESULTS: The success rates of direct biopsies performed in 0.02 cc lesion group and 0.1cc group with the distance of 1.5cm were 66.6% and 86.7%, showing a statistically significant difference from other groups (p < 001). The diagnosis rates for 4, 6 and 8 times of random biopsies on 0.1 cc lesions were 6.7%, 23.3% and 36.7%, and the difference was statistically significant (p < 0.01). At the same time, the diagnosis rates for 4, 6 and 8 times of random biopsies on 0.5 cc lesions were 56.7%, 80% and 90%, also exhibiting a statistically significant difference (p < 0.01). CONCLUSION: The success rates of direct TRUS-guided biopsies decreased when the sizes of the targeted lesions was smaller and when the distance of lesions from the posterior surface increased. Not only the detection rate of the clinically significant lesions but also the detection rate for the clinically insignificant lesions increased as the number of systematic random biopsies increased.