Elsevier

European Urology

Volume 66, Issue 2, August 2014, Pages 343-351
European Urology

Prostate Cancer
A Prospective, Blinded Comparison of Magnetic Resonance (MR) Imaging–Ultrasound Fusion and Visual Estimation in the Performance of MR-targeted Prostate Biopsy: The PROFUS Trial

https://doi.org/10.1016/j.eururo.2013.10.048Get rights and content

Abstract

Background

Increasing evidence supports the use of magnetic resonance (MR)–targeted prostate biopsy. The optimal method for such biopsy remains undefined, however.

Objective

To prospectively compare targeted biopsy outcomes between MR imaging (MRI)–ultrasound fusion and visual targeting.

Design, setting, and participants

From June 2012 to March 2013, prospective targeted biopsy was performed in 125 consecutive men with suspicious regions identified on prebiopsy 3-T MRI consisting of T2-weighted, diffusion-weighted, and dynamic-contrast enhanced sequences.

Intervention

Two MRI–ultrasound fusion targeted cores per target were performed by one operator using the ei-Nav|Artemis system. Targets were then blinded, and a second operator took two visually targeted cores and a 12-core biopsy.

Outcome measurements and statistical analysis

Biopsy information yield was compared between targeting techniques and to 12-core biopsy. Results were analyzed using the McNemar test. Multivariate analysis was performed using binomial logistic regression.

Results and limitations

Among 172 targets, fusion biopsy detected 55 (32.0%) cancers and 35 (20.3%) Gleason sum ≥7 cancers compared with 46 (26.7%) and 26 (15.1%), respectively, using visual targeting (p = 0.1374, p = 0.0523). Fusion biopsy provided informative nonbenign histology in 77 targets compared with 60 by visual (p = 0.0104). Targeted biopsy detected 75.0% of all clinically significant cancers and 86.4% of Gleason sum ≥7 cancers detected on standard biopsy. On multivariate analysis, fusion performed best among smaller targets. The study is limited by lack of comparison with whole-gland specimens and sample size. Furthermore, cancer detection on visual targeting is likely higher than in community settings, where experience with this technique may be limited.

Conclusions

Fusion biopsy was more often histologically informative than visual targeting but did not increase cancer detection. A trend toward increased detection with fusion biopsy was observed across all study subsets, suggesting a need for a larger study size. Fusion targeting improved accuracy for smaller lesions. Its use may reduce the learning curve necessary for visual targeting and improve community adoption of MR-targeted biopsy.

Introduction

Although increasing evidence supports use of multiparametric magnetic resonance imaging (mpMRI)-targeted biopsy (MR-TB) in clinical practice, the optimal methodology for targeting magnetic resonance imaging (MRI)-suspicious regions (mSR) remains unknown [1], [2], [3], [4], [5], [6]. In-gantry prostate biopsy of mSR using real-time magnetic resonance (MR) guidance has been reported to have excellent outcomes, but the technique remains restricted to a few centers and is limited by multiple challenges, including a steep learning curve, time investment and the opportunity cost of magnet time [7], [8], [9], [10], [11]. Many investigators have used a visual, or cognitive, guidance technique in which the surgeon samples a visually estimated location on ultrasound that corresponds to the mSR location (VE-TB) [12], [13], [14]. The accuracy of MR-TB is influenced by multiple variables, including mSR size, alignment of prostate landmarks, and operator experience [15].

Software-based coregistration of MRI–ultrasound (MRI-US) targeted biopsy (MRF-TB) requires demarcation of mSR on prebiopsy MR images and software “fusion” of these images during real-time ultrasound imaging. Several MRF-TB platforms exist, but their accuracy compared with VE-TB remains unclear. Consequently, we undertook a prospective, blinded comparison of MRF-TB and VE-TB among men undergoing prostate biopsy.

Section snippets

Study design and population

After receiving institutional review board approval, enrollment began on June 18, 2012, and closed on March 19, 2013. Consecutive men presenting for prostate biopsy underwent prebiopsy mpMRI and were offered inclusion on identification of any mSR. If included, all patients underwent informed consent. Over this period, 210 men presented for prostate biopsy, and 193 (91.9%) underwent mpMRI. Seventeen men (8.1%) were excluded because of MRI contraindications. Prebiopsy mpMRI demonstrated no

Study population

The clinical characteristics for these groups are detailed in Table 1. Among 125 men enrolled, 67 (54%) had had no prior prostate biopsy (group 1), 34 (27%) had had a prior negative prostate biopsy (group 2), and 24 (19%) had been previously diagnosed with low-risk cancer on active surveillance (group 3).

The study targeted 172 separate mSR, with an overall median suspicion score of 3 [2.0–4.0]. Single targets were present in 76 patients (60.8%), while 48 men (38.4%) had two separate mSR. A

Discussion

Much of the current dilemma regarding prostate cancer (PCa) screening, detection, and appropriate treatment can be attributed to the use of random sampling methods for prostate biopsy [20], [21], [22]. Standard biopsy relies on sampling efficiency for cancer detection, which intrinsically risks the consequences of sampling error: undersampling, oversampling, and inaccurate risk stratification [23]. Despite increasing evidence to support a benefit for MR-TB in PCa detection, the optimal method

Conclusions

In this study, MRF-TB was more often histologically informative than VE-TB, and although it did not provide a higher CDR, a trend toward an improved CDR with MRF-TB was noted in all subsets, suggesting a need for a larger sample size. Targeting was improved by MRF among smaller lesions. A software-based coregistration tool would likely assist the community adoption of MRI-TB, especially in centers that have limited experience with visual targeting. This study prompts additional work into the

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