EURURO Vol. 71 No. 4

532 692

Platinum Priority – Editorial
Referring to the article published on pp. 517–531 of this issue
Magnetic [1_TD$DIFF]Resonance Imaging–targeted Prostate Biopsies:
Is the Right Technique the Right Question?
Matthew R. Cooperberg
Departments of Urology and Epidemiology & Biostatistics, UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, USA
In recent years, the literature on prostate cancer has been
flooded with papers trumpeting the value of multipara-
metric magnetic resonance imaging (MRI) and MRI-guided
biopsies for the management of prostate cancer, and some
ardent advocates have even begun to question the value of
systematic transrectal ultrasound (TRUS)–guided biopsy. To
summarize the current state of the evidence, in the current
issue of European Urology, Wegelin et al report a
systematic evidence review regarding various approaches
to MRI biopsy compared to TRUS biopsy.
Not particularly surprisingly, MRI biopsy and TRUS biopsy
had similar rates of overall cancer detection. MRI biopsy
tended to find more ‘‘clinically significant’’ prostate cancers —
by a relatively small margin — and miss more insignificant
cancers than TRUS biopsy. Critical to these analyses, of course,
is the definition of ‘‘clinically significant.’’ Reflecting the
marginal quality of much of the existing literature, this
definition was quite variable across the papers included in the
review; some studies did not report this endpoint at all, and
several used multiple definitions. A few used the Epstein
criteria, which are surely too liberal in defining ‘‘significant’’
based on tumor size, whereas others only counted Gleason
4 + 3 tumors as ‘‘significant,’’ discounting even high-volume
Gleason 3 + 4 tumors. This heterogeneity precludes any
recommendation for clinical practice based on the existing
literature (ie, missing 10% of tumors failing Epstein criteria for
‘‘insignificant’’ might not be a problem, but missing 10% of
Gleason 4 + 3 tumors would be).
MRI-guided biopsy can be performed using a number of
techniques. In the simplest, ‘‘cognitive fusion’’, the urologist
reviews the MRI before the biopsy and makes sure to focus
attention on the area(s) highlighted by MRI. Cognitive
fusion is the quickest and least expensive of MRI fusion
options, and certainly makes sense in the hands of a good
ultrasonographer. Indeed, the incremental value of MRI is
tightly — and inversely — proportional to the quality of the
TRUS. TRUS should not simply guide the biopsy needle to
different regions of the prostate; rather, the images should
be scrutinized in real time for hypoechoic lesions, visible to
experienced practitioners for a majority of cancers, with a
high positive predictive value The anterior zones may
also be routinely sampled with minimal additional effort.
The second option for MRI-guided biopsy is MRI fusion
biopsy, in which the MRI-identified lesion is directly
mapped onto the ultrasound image, using software to
account for variable segmentation and deformation be-
tween TRUS and MRI. MRI fusion requires dedicated
equipment, and multiple platforms are available for clinical
use; none has been shown to be superior to any other to
date. Finally, biopsy can be formed in-bore in an open MRI
magnet. This approach is the most accurate in terms of
targeting the visible lesion, but is also the most cumber-
some and expensive, and does not readily allow for
simultaneous systematic biopsy.
One of the more remarkable findings in the analysis by
Wegelin et al is that no technique was better that any
other for identifying ‘‘substantial’’ prostate cancer. If true,
significant time and cost savings could be realized via
cognitive rather than software-based fusion or in-bore
biopsy. However, given the definition heterogeneity de-
scribed above and the small numbers of studies reporting
this endpoint for cognitive fusion and in-bore biopsy, the
null finding must be interpreted quite cautiously. An
ongoing randomized trial organized by the authors of the
available at
journal homepage:
DOI of original article: .
* Departments of Urology and Epidemiology & Biostatistics, UCSF Helen Diller Family Comprehensive Cancer Center, 550 16th Street, San Francisco, CA
94143, USA. Tel. +1 415 8853660; Fax: +1 415 8857443.
E-mail address:
0302-2838/# 2016 European Association of Urology. Published by Elsevier B.V. All rights reserved.