A biopsy simulation study to assess the accuracy of several transrectal ultrasonography (TRUS)-biopsy strategies compared with template prostate mapping biopsies in patients who have undergone radical prostatectomy


Hashim Uddin Ahmed, Division of Surgery and Interventional Science, 67 Riding House Street, Fitzrovia, University College London, London W1P 7NN, UK. e-mail: hashim.ahmed@ucl.ac.uk


Study Type – Diagnostic (validating cohort)

Level of Evidence 1b

What's known on the subject? and What does the study add?

Transrectal ultrasonography (TRUS)-guided biopsies can miss prostate cancer and misclassify risk in a diagnostic setting; the exact extent to which it does so in a repeat biopsy strategy in men with low–intermediate risk prostate cancer is unknown.

A simulation study of different biopsy strategies showed that repeat 12-core TRUS biopsy performs poorly. Adding anterior sampling improves on this but the highest accuracy is achieved using transperineal template prostate mapping using a 5 mm sampling frame.


  • • To determine the effectiveness of two sampling strategies; repeat transrectal ultrasonography (TRUS)-biopsy and transperineal template prostate mapping (TPM) to detect and exclude lesions of ≥0.2 mL or ≥0.5 mL using computer simulation on reconstructed three-dimensional (3-D) computer models of radical whole-mount specimens.


  • • Computer simulation on reconstructed 3-D computer models of radical whole-mount specimens was used to evaluate the performance characteristics of repeat TRUS-biopsy and TPM to detect and exclude lesions of ≥0.2 mL or ≥0.5 mL.
  • • In all, 107 consecutive cases were analysed (1999–2001) with simulations repeated 500 times for each biopsy strategy.
  • • TPM and five different TRUS-biopsy strategies were simulated; the latter involved a standard 12-core sampling and incorporated variable amounts of error, as well as the addition of anterior cores.
  • • Sensitivity, specificity, negative and positive predictive values for detection of lesions with a volume of ≥0.2 mL or ≥0.5 mL were calculated.


  • • The mean (sd) age and PSA concentration were 61 (6.4) years and 8.5 (5.9) ng/mL, respectively.In all, 53% (57/107) had low–intermediate risk disease.
  • • In all, 665 foci were reconstructed; there were 149 foci ≥0.2 mL and 97 ≥ 0.5 mL in the full cohort and 68 ≥ 0.2 mL and 43 ≥ 0.5 mL in the low–intermediate risk group.
  • • Overall, TPM accuracy (area under the receiver operating curve, AUC) was ≈0.90 compared with AUC 0.70–0.80 for TRUS-biopsy.
  • • In addition, at best, TRUS-biopsy missed 30–40% of lesions of ≥0.2 mL and ≥0.5 mL whilst TPM missed 5% of such lesions.


  • • TPM under simulation conditions appears the most effective re-classification strategy, although augmented TRUS-biopsy techniques are better than standard TRUS-biopsy.