title: 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.
abstract: 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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  TPM under simulation conditions appears the most effective re-classification strategy, although augmented TRUS-biopsy techniques are better than standard TRUS-biopsy.
authors.affiliation: Centre for Medical Image Computing, University College London (UCL), London, UK.
authors.forename: Yipeng
authors.initials: Y
authors.lastname: Hu
authors.forename: Hashim U
authors.initials: HU
authors.lastname: Ahmed
authors.forename: Tim
authors.initials: T
authors.lastname: Carter
authors.forename: Nimalan
authors.initials: N
authors.lastname: Arumainayagam
authors.forename: Emilie
authors.initials: E
authors.lastname: Lecornet
authors.forename: Winston
authors.initials: W
authors.lastname: Barzell
authors.forename: Alex
authors.initials: A
authors.lastname: Freeman
authors.forename: Pierre
authors.initials: P
authors.lastname: Nevoux
authors.forename: David J
authors.initials: DJ
authors.lastname: Hawkes
authors.forename: Arnauld
authors.initials: A
authors.lastname: Villers
authors.forename: Mark
authors.initials: M
authors.lastname: Emberton
authors.forename: Dean C
authors.initials: DC
authors.lastname: Barratt
mesh_terms: D000328:Adult; D000368:Aged; D001707:Biopsy, Needle / Q000379:methods*; D003198:Computer Simulation; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000000981:diagnostic imaging / Q000473:pathology*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D015203:Reproducibility of Results; D018084:Ultrasonography, Interventional