EURURO Vol. 71 No. 4

Introduction

Prostate cancer (PCa) is the most common malignancy

among European men

[1] .

PCa incidence is expected to

increase due to prostate-specific antigen (PSA) testing and

aging of the general population

[1] .

The introduction of PSA

testing led to an increased PCa incidence, while mortality

from PCa has decreased

[2,3]

. Disadvantages of PSA

screening are the risks of overdiagnosis and overtreatment

of clinically insignificant PCa

[3]

The current standard technique for PCa detection is

transrectal ultrasound-guided biopsy (TRUS-GB). Using

TRUS-GB the prostate is randomly sampled for the presence

of PCa, and has its limitations due to the inability of grey-

scale ultrasonography to distinguish PCa from benign tissue

[4,5]

. Consequently, TRUS-GB is renowned for its low

sensitivity and specificity for PCa. This is underlined by the

fact that repeat TRUS-GB due to persisting clinical suspicion

on PCa, leads to the diagnosis of PCa in 10–25% of cases

following a prior negative biopsy

[6,7]

. Furthermore,

Gleason grading in radical prostatectomy specimens

demonstrates upgrading in 36% when compared with

preoperative grading using TRUS-GB

[8] .

Developments of

multiparametric MRI (mpMRI) techniques have increased

the sensitivity of imaging for PCa

[9–12]

. According the

European Society of Urogenital Radiology (ESUR) guidelines

an mpMRI consists of T2-weighted images, dynamic

contrast enhanced imaging, and diffusion weighted imaging

[13]

. Usage of a 3 Tesla (3-T) magnet has further enhanced

resolution and quality of imaging compared with 1.5-T

[13]

. Clinical guidelines advise performing an mpMRI when

initial TRUS biopsy results are negative but the suspicion of

PCa persists

[4] .

A standardised method for mpMRI evaluation was

developed in order to increase inter-reader reliability and

meaningful communication towards clinicians

[13]

. The

Prostate Imaging-Reporting and Data System (PI-RADS)

classification was introduced in 2012 by the ESUR, and has

recently been updated to version 2.0.

[13–15]

. It evaluates

lesions within the prostate on each of the three imaging

modalities (T2-weighted, diffusion weighted imaging, and

dynamic contrast enhanced) using a 1–5 scale, and

additionally each lesion is given an overall score between

1 and 5 predicting its chance of being a clinically significant

cancer

[13–15]

Classically the definition of clinically significant PCa

(csPCa) was based on the Epstein criteria

[16,17]

and

d’Amico classification

[18,19]

. These classifications are

based on random TRUS-GB outcomes. Due to the introduc-

tion of target biopsy procedures the preoperative definition

of csPCa has changed. For that reason a number of new

definitions of csPCa have been proposed, though as yet none

have been widely adopted

[20–23]

Various strategies for targeted biopsy of lesions on MRI

have been developed, and demonstrate increased detection

rates of csPCa compared with TRUS-GB

[24–28]

. Currently

no consensus exists on which strategy of targeted biopsy

should be preferred. Existing strategies of MRI guided

biopsy (MRI-GB) include: (1) in-bore MRI target biopsy

(MRI-TB) which is performed in the MRI suite using real-

time MRI guidance

[26,28]

, (2) MRI-TRUS fusion target

biopsy (FUS-TB) where software is used to perform a MRI

and TRUS image fusion, which allows direct target biopsies

of MRI identified lesions using MRI-TRUS fusion image

guidance

[29–32] ,

(3) cognitive registration TRUS targeted

biopsy (COG-TB) where the MRI is viewed preceding the

biopsy, and is used to

cognitively

target the MRI identified

lesion using TRUS guidance

[33,34]

The aim of this systematic review is to answer the

following questions. In men at risk for PCa (based on an

elevated PSA [

4.0 ng/ml] and/or abnormal digital rectal

examination):

Does MRI-GB lead to increased detection rates of csPCa

compared with TRUS-GB?

Is there a difference in detection rates of csPCa between

the three available strategies of MRI-GB?

Evidence acquisition

2.1.

Search strategy

A search strategy was designed using the STARLITE

methodology

[35]

. A comprehensive search of literature

was performed. A range of the last 10 yr was used since

mpMRI has evolved rapidly in the last decade, and literature

dating further back is not considered useful for current

practise. No other search limits were applied. The search

terms used were ‘‘Prostate OR Prostatic Neoplasm’’ AND

‘‘Biopsy’’ AND ‘‘Magnetic Resonance Imaging OR Image-

Guided Biopsy’’ (see Appendix 1 for the complete search

query). The search was assisted by an information specialist

on October 27, 2014 using the PubMed, Embase, and

CENTRAL databases.

Conclusions:

MRI-GB had similar overall PCa detection rates compared with TRUS-GB,

increased rates of csPCa, and decreased rates of insignificant PCa. MRI-TB has a superior

overall PCa detection compared with COG-TB. FUS-TB and MRI-TB appear to have similar

detection rates. Head-to-head comparisons of MRI-GB techniques are limited and are

needed to confirm our findings.

Patient summary:

Our review shows that magnetic resonance imaging-guided biopsy

detects more clinically significant prostate cancer (PCa) and less insignificant PCa compared

with systematic biopsy in men at risk for PCa.

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