Value of targeted prostate biopsy using magnetic resonance-ultrasound fusion in men with prior negative biopsy and elevated prostate-specific antigen

Abstract

Background: Conventional biopsy fails to detect the presence of some prostate cancers (PCas). Men with a prior negative biopsy but persistently elevated prostate-specific antigen (PSA) pose a diagnostic dilemma, as some harbor elusive cancer.

Objective: To determine whether use of magnetic resonance-ultrasound (MR-US) fusion biopsy results in improved detection of PCa compared to repeat conventional biopsy.

Design, setting, and participants: In a consecutive-case series, 105 subjects with prior negative biopsy and elevated PSA values underwent multiparametric magnetic resonance imaging (MRI) and fusion biopsy in an outpatient setting.

Intervention: Suspicious areas on multiparametric MRI were delineated and graded by a radiologist; MR-US fusion biopsy was performed by a urologist using the Artemis device; targeted and systematic biopsies were obtained regardless of MRI result.

Outcome measurements and statistical analysis: Detection rates of all PCa and clinically significant PCa (Gleason ≥3+4 or Gleason 6 with maximal cancer core length ≥4 mm) were determined. The yield of targeted biopsy was compared to systematic biopsy. The ability of an MRI grading system to predict clinically significant cancer was investigated. Stepwise multivariate logistic regression analysis was performed to determine predictors of significant cancer on biopsy.

Results and limitations: Fusion biopsy revealed PCa in 36 of 105 men (34%; 95% confidence interval [CI], 25-45). Seventy-two percent of men with PCa had clinically significant disease; 21 of 23 men (91%) with PCa on targeted biopsy had significant cancer compared to 15 of 28 (54%) with systematic biopsy. Degree of suspicion on MRI was the most powerful predictor of significant cancer on multivariate analysis. Twelve of 14 (86%) subjects with a highly suspicious MRI target were diagnosed with clinically significant cancer.

Conclusions: MR-US fusion biopsy provides improved detection of PCa in men with prior negative biopsies and elevated PSA values. Most cancers found were clinically significant.

Keywords: Magnetic resonance imaging; Prostate biopsy; Prostate cancer; Ultrasound.

Copyright © 2013 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Figures

Fig. 1

Example of fusion biopsy. The patient is a 72-yr-old man with a prostate-specific antigen value of 18.2 ng/ml, a prostate volume of 75 ml, and two prior negative biopsies. (A) A three-dimensional model of the prostate (brown) was created in the Artemis device, fusing magnetic resonance imaging (MRI) and real-time ultrasound images. An optimally spaced 12-core systematic biopsy map (green spots) is automatically generated. An area of interest on MRI, assigned image grade 5 by the radiologist, is shown fused within the model (blue spot marked as a target numbered 13). In this patient, mapped spot 9 overlies the target 13. (B) A 12-core systematic biopsy was performed at mapped sites. Recorded locations of biopsy cores are shown as black cylinders. The MRI target was sampled with five targeted cores and one systematic core (mapped spot 9). All six cores showed Gleason 9 prostate cancer. Other biopsies were negative.

Fig. 2

This per-target analysis shows the proportion of all cancers (hatched) and clinically significant cancers (dotted) stratified by image grade on magnetic resonance imaging scans. For example, 75% of the 16 image grade 5 targets identified in the 105 patients had clinically significant cancer identified in at least one of the targeted biopsy cores. PCa = prostate cancer. * Targeted biopsies were not taken from men (n = 4) with a normal magnetic resonance imaging scan (image grade 1).

Fig. 3

This per-patient analysis shows the number of subjects diagnosed with significant cancers (dotted) and insignificant cancers (hatched) depending on biopsy method. Clinically significant cancer was based on definition 2 (Gleason >6 or ≥4 mm maximal core length). PCa = prostate cancer.