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EUROPEAN UROLOGY 59 (2011) 962–977
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Review – Prostate Cancer
Advances in Magnetic Resonance Imaging: How They Are
Changing the Management of Prostate Cancer
Alessandro Sciarra a,*, Jelle Barentsz b, Anders Bjartell c, James Eastham d, Hedvig Hricak e,
Valeria Panebianco f, J. Alfred Witjes g
a
Department of Urology, Sapienza University of Rome, Rome, Italy
b
Department of Radiology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
c
Department of Urology, Skåne University Hospital, Malmö, Sweden
d
Department of Surgery, Memorial Sloan-Kettering Cancer Center, Sidney Kimmel Center for Prostate and Urologic Cancers, New York, NY, USA
e
Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
f
Department of Radiology, University Sapienza of Rome, Rome, Italy
g
Department of Urology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
Article info
Abstract
Article history:
Accepted February 15, 2011
Published online ahead of
print on February 22, 2011
Context: Although magnetic resonance imaging (MRI) is emerging as the most commonly used imaging modality for prostate cancer (PCa) detection, treatment planning,
and follow-up, its acceptance has not been uniform. Recently, great interest has been
shown in multiparametric MRI, which combines anatomic T2-weighted (T2W) imaging
with MR spectroscopic imaging (MRSI), dynamic contrast-enhanced MRI (DCE-MRI), and
diffusion-weighted imaging (DWI).
Objective: The aim of this article is to review the current roles of these MR techniques in
different aspects of PCa management: initial diagnosis, biopsy strategies, planning of
radical prostatectomy (RP) and external radiation therapy (RT), and implementation of
alternative focal therapies.
Evidence acquisition: The authors searched the Medline and Cochrane Library databases
(primary fields: prostatic neoplasm, magnetic resonance). The search was performed
without language restriction from January 2008 to November 2010.
Evidence synthesis: Initial diagnosis: The data suggest that the combination of T2W MRI
and DWI or MRSI with DCE-MRI has the potential to guide biopsy to the most aggressive
cancer foci in patients with previously negative biopsies, increasing the accuracy of the
procedure. Transrectal MR-guided prostate biopsy can improve PCa detection, but its
availability is still limited and the examination time is rather long. Planning of RP: It
appears that adding MRSI, DWI, and/or DCE-MRI to T2W MRI can facilitate better
preoperative characterization of cancer with regard to location, size, and relationship
to prostatic and extraprostatic structures, and it may also facilitate early detection of
local recurrence. Thus, use of these MR techniques may improve surgical, oncologic, and
functional management. Planning of external RT and focal therapies: MR techniques have
similar potential in these areas, but the published data remain very limited.
Conclusions: MRI technology is continuously evolving, and more extensive use of MRI
technology in clinical trials and practice will help to improve PCa diagnosis and
treatment planning.
# 2011 European Association of Urology. Published by Elsevier B.V. All rights reserved.
Keywords:
Prostate neoplasm
Imaging
Magnetic resonance
* Corresponding author. Department of Urology – Prostate Unit, University Sapienza–Policlinico
Umberto I, Viale Policlinico 155, 00161 Rome, Italy. Tel.: +39 06 4461959; Fax: +39 06 4461959.
E-mail address: [email protected] (A. Sciarra).
0302-2838/$ – see back matter # 2011 European Association of Urology. Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.eururo.2011.02.034
EUROPEAN UROLOGY 59 (2011) 962–977
1.
Introduction
At present, the evaluation and the management of
prostate cancer (PCa) are based mainly on parameters
such as the serum prostate-specific antigen (PSA) level,
clinical stage, and pathologic findings at biopsy or after
surgery [1,2]. The three cross-sectional imaging modalities—
computed tomography (CT), ultrasonography, and magnetic
resonance imaging (MRI)—have been tested in PCa patients,
and they all have substantial limitations [3]. Recently, great
interest has been shown in multiparametric MRI, which
combines anatomic T2-weighted (T2W) imaging with MR
spectroscopic imaging (MRSI), diffusion-weighted imaging
(DWI), and/or dynamic contrast-enhanced MRI (DCE-MRI).
The combination of anatomic, biologic, and functional
dynamic information offered by multiparametric MRI
promises to make it a successful imaging tool for improving
many aspects of PCa management. There is a real need for
clinicians to base therapeutic decisions not only on predictive
methods and nomograms that include PSA, digital rectal
examination (DRE) findings, and transrectal ultrasound
(TRUS) biopsy findings, but also on imaging.
2.
Evidence acquisition
The aim of this article is to review the current roles of
multiparametric MRI techniques in different phases of
PCa diagnosis and management and to suggest how these
MR techniques may help address clinicians’ questions.
We searched the Medline and Cochrane Library databases
(primary fields: prostatic neoplasm, magnetic resonance;
secondary fields: humans, spectroscopy, dynamic contrast, diffusion, early diagnosis, prostate biopsy, radical
prostatectomy [RP], external radiation therapy [RT], focal
therapies, recurrence). The search was performed without
language restriction from January 2008 to November
2010. The search was limited to those 3 yr to produce an
up-to-date article focussed only on very recent studies.
3.
Evidence synthesis
3.1.
Technical aspects
Traditionally, MRI for PCa has been performed with a
1.5-Tesla (1.5T) scanner and endorectal coil. With the
introduction of a higher field strength (3T), and, thus, higher
spatial resolution, the endorectal surface coil can be used
less frequently, which makes MRI more accessible [4,5].
Intense research has focussed on the use of complementary
techniques to improve the detection, characterization, and
staging of PCa by MRI. Proton MRSI provides metabolic
information, DWI shows the Brownian motion of extracellular water molecules, and DCE-MRI visualises tissue
vascularity, especially neoangiogenesis [6,7].
3.1.1.
Magnetic resonance spectroscopic imaging
With MRSI, three-dimensional (3D) data are acquired from
the prostate, with volume elements (voxels) ranging
from 0.24 cm3 to 0.34 cm3 [8]. MRSI shows the relative
963
concentrations of certain metabolites within voxels. In the
prostate, the substances analyzed by MRSI are citrate,
creatine, and choline. In PCa, citrate levels are reduced;
creatine and choline levels are elevated. PCa can be distinguished from healthy peripheral zone tissue on the basis of
the choline plus creatine-to-citrate ratio [9]. Unfortunately,
some benign conditions, such as prostatitis and postbiopsy
changes, may also result in an increase of the ratio [3,8]. MRSI
is an accurate technique to localise and characterise PCa,
and to monitor changes indicating progression or treatment
response. MRSI requires a longer acquisition time and more
expertise than other functional MRI techniques.
3.1.2.
Diffusion-weighted imaging
In DWI, proton diffusion properties within water are used to
obtain image contrast. The extracellular and intraductal
water molecules move freely; therefore, in healthy prostate
tissue within the peripheral zone, the so-called apparent
diffusion coefficient (ADC) values are high. PCa tissue
destroys the normal glandular structure of the prostate and
also has a higher cellular density than healthy prostate
tissue, resulting in decreased extracellular space. Therefore,
the water molecule movement is restricted in PCa, and PCa
shows lower ADC values than surrounding, healthy,
peripheral-zone prostate tissue [6,8]. DWI examination
can be obtained rapidly without the use of contrast
medium. Thus, of all the functional MRI techniques, DWI
is the most practical and simple to use. DWI has the
disadvantages of being susceptible to motion and magneticfield homogeneities.
3.1.3.
Dynamic contrast-enhanced magnetic resonance imaging
DCE-MRI consists of the acquisition of sequential images
using T1-weighted sequences during the passage of a
contrast agent (gadopentetate dimeglumine) within the
prostatic tissue. The pharmacokinetics of gadolinium-based
contrast agents in the prostate produce different enhancement patterns in PCa and benign tissues. The technique is
based on the assessment of neoangiogenesis, which is an
integral feature of tumours. DCE-MRI parameters can often
be estimated both qualitatively and quantitatively, and the
parameters frequently reported are onset time of signal
enhancement, time to peak, peak enhancement, and
washout [3]. DCE-MRI is limited by a lack of standardised
acquisition protocols and analytic models. DCE-MRI has
high sensitivity, which can be useful for initial evaluation of
potential tumour locations.
3.2.
Initial diagnosis and biopsy strategies
3.2.1.
Initial diagnosis and indication for prostate biopsy
As defined by the 2010 European Association of Urology
guidelines [1], the primary methods for diagnosing PCa
include DRE, testing for serum concentration of PSA, and
TRUS-guided prostate biopsy.
Individually, the functional MRI techniques (MRSI, DWI,
and DCE-MRI) have shown the potential to add value
to conventional anatomic MRI in PCa detection (Fig. 1)
[10–14]. Because they have relatively high specificity in
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[()TD$FIG]
EUROPEAN UROLOGY 59 (2011) 962–977
Fig. 1 – Patient (age: 56 yr) with prostate-specific antigen level of 11 ng/ml; no suspicious findings at digital rectal examination. Histology at
transrectal ultrasound-guided biopsy showed prostate adenocarcinoma (PCa), Gleason score 7 (3 + 4) in the left-side samples; histology at radical
retropubic prostatectomy showed Gleason score 7 (4 + 3) PCa with extracapsular extension (ECE) in the left peripheral zone (PZ) indicating stage
pT3a. (A) Axial T2-weighted magnetic resonance (MR) image shows low signal intensity lesion in the left PZ (outlined in white), which is suggestive of
PCa with ECE (arrow). (B) MR spectroscopic imaging (MRSI) of tumour (blue box in [a]): high citrate (Ci), high choline (Ch) plus creatine (Cr). (C) MRSI
of normal prostate area in right PZ (yellow box in [a]): high Ci, low Ch plus Cr. (D) Axial dynamic contrast-enhanced MR image showing leakage of
contrast medium both in tumour (white circle) in the left PZ and in some benign prostatic hyperplasia areas (arrows). (E) Axial apparent diffusion
coefficient map from diffusion-weighted imaging shows restriction (ie, low signal intensity) (T) in the left PZ, which may be suggestive of an area of
Gleason grade 4 PCa.
comparison with PSA, their use could prevent unnecessary,
systematic, random biopsies and delay of diagnosis and
treatment (Table 1). It is essential to know if combining
more than one functional MR technique could improve
results even further. In a small prospective study (19 cases),
which used prostatectomy as the standard of reference, the
combination of DWI with either MRSI or DCE-MRI (1.5T
MRI) increased area under the curve (AUC) values for
detection of PCa tumours 1 cm2 from 0.65–0.71 to 0.94.
Adding a third functional MRI technique did not further
improve detection (the AUC value for DWI, DCE, and MRSI
together was 0.95) [11]. In a recent logistic regression
analysis (42 cases with prostatectomy as the standard of
reference), the ADC value at DWI (AUC = 0.69) was the best
performing single parameter for PCa detection when
compared with T2-weighted imaging and DCE-MRI parameters [10]. Because the clinical significance of PCa is related
to Gleason grades, Villeirs et al. [15] investigated in 356
subjects (mean serum PSA = 11.5 ng/ml) the ability of MRSI
(1.5T MRI) to predict the presence or absence of high-grade
(Gleason score 4 + 3) PCa in men with elevated PSA. They
found MRSI had significantly higher sensitivity for highgrade PCa (92.7%) than for lower grade tumours (67.6%) and
a 7.4% false-positive rate.
Multiparametric MRI techniques may also contribute to
the detection of transition-zone PCa. In a retrospective
Table 1 – Initial diagnosis and determination of need for prostate
biopsy
Actual diagnostic
tools
What MRI
could offer
Potential limits
of MRI
Digital rectal examination
Prostate-specific antigen and its derivatives
Prostate cancer antigen 3 gene (PCA3)
Nomograms
Reduction of indications for nonuseful biopsy
procedures
Identification of patients at risk for clinically
significant prostate cancer
The difficulties of merging multiparametric MRI
with TRUS to direct TRUS-guided biopsies
MRI = magnetic resonance imaging; TRUS = transrectal ultrasound.
EUROPEAN UROLOGY 59 (2011) 962–977
[()TD$FIG]
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Table 2 – Biopsy strategy
Actual diagnostic
tools
What MRI
could offer
Potential limits
of MRI
Random biopsies
Schemes based on prostate volume
Saturation biopsy
Analysis of the whole prostate gland
Identification of areas at higher
risk for prostate cancer appropriate
for targeted biopsy sampling
Biopsies targeted on imaging
Guidance during biopsy performance
Reduced need for repeated biopsies
Correct identification of the areas described at
MRI in a TRUS-guided biopsy
Need of a special equipment for MRI-guided biopsy
MRI = magnetic resonance imaging; TRUS = transrectal ultrasound.
study of 23 patients, the addition of DWI and DCE-MRI to
T2-weighted MRI increased accuracy in the detection of
transition-zone cancer from 64% to 79% [16]. However,
additional research is needed to confirm these initial
results.
3.2.2.
Fig. 2 – Biopsy scheme of the entire gland volume. Note potential biopsy
sites based on magnetic resonance imaging morphologic, metabolic, and
vascularisation changes in the medial and lateral left peripheral zone
(planes IV, V, VI; gland area between 4 and 5).
Biopsy strategies
Random TRUS-guided biopsy is now the preferred method
for histologic diagnosis of PCa. However, sextant biopsies
have been reported to miss up to 30% of cancers, and when
compared with RP for tumour localization, biopsy results
had a positive predictive value (PPV) and a negative
predictive value (NPV) of 83% and 36%, respectively
[17,18]. Although MRSI is not used at this time as a first
approach to diagnose PCa, it can be useful for directing
targeted biopsies, especially for patients with PSA levels
suggestive of cancer and negative previous biopsies (Table
2). Men with persistently elevated serum PSA levels after a
negative random TRUS-guided biopsy represent a great
diagnostic problem for urologists. Biopsy strategies with an
increased number of cores have also been proposed to
reduce false-negative rates. However, such saturation
biopsies can be associated with increased patient morbidity, and controversy persists over whether taking more cores
results in the detection of more tumours with low-risk
characteristics.
In a limited population of 54 men with elevated PSA
levels and previous negative biopsy results, Cirillo et al. [14]
found that the use of MRSI combined with MRI at 1.5T had
100% sensitivity, 51.4% specificity, 48.6% PPV, 100% NPV,
and 66.3% accuracy in indicating sites of PCa. Sciarra et al.
[18] performed a prospective study of 180 patients with
prior negative random biopsy results and persistently
elevated PSA levels. Patients were randomised to a second
random prostate biopsy or to multiparametric 1.5T MRI
(MRSI/DCE-MRI) followed by random prostate biopsy with
additional targeted sampling of suspicious areas identified
on multiparametric MRI (Fig. 2). At the second biopsy, PCa
was found in 24.4% of cases in the first group versus 45.5% in
the group that underwent multiparametric MRI. The
combination of MRSI plus DCE-MRI had 93% sensitivity,
89% specificity, 89% PPV, 93% NPV, and 91% accuracy for
predicting PCa detection. Thus, the combination of MRSI
and DCE-MRI has the potential to guide biopsy to cancer foci
in patients with negative prior biopsy results. To avoid
interferences caused by postbiopsy changes, the MRI
examination should be performed successfully as early as
60 d after the first biopsy. Laurentschuk and Fleshner [19]
reviewed all available databases from prospective studies of
patients with previous negative biopsy results and persistently elevated PSA levels who underwent MRSI and repeat
prostate biopsy. Among the six studies that fulfilled
the criteria, MRSI had sensitivity of 57–100%, specificity
of 44–96%, and accuracy of 67–85% in the prediction of
positive repeat-biopsy results [19].
Recently, some studies have also analysed the practicability of MR-guided biopsy (Fig. 3). Hambrock et al. [20]
tested the feasibility of translating maps of potential areas
of tumour in the prostate, obtained from multiparametric
3T MRI data (including T2W MRI, DWI, and DCE-MRI), for
directing MR-guided biopsies. Results from 21 patients with
elevated PSA levels and negative previous biopsy results
were analysed. All areas of suspected tumour identified on
multiparametric MRI were translated to 3T T2W MRI and
biopsied under MR guidance. MR-guided biopsy procedure
time was 35 min.
In 68 patients with similar characteristics, Hambrock
and colleagues [21] analyzed the results of multiparametric
3T MR-guided biopsy and compared them with results from
a matched population of patients who underwent multisession TRUS-guided biopsy. The tumour detection rate for
MR-guided biopsy was 59% using a median of four cores,
and it was significantly ( p < 0.001) higher than that of
TRUS-guided prostate biopsy. Yakar et al. [22] and Pondman
et al. [23] have provided additional data showing that, in
patients with prior negative TRUS-guided biopsy results, 3T
MR-guided prostate biopsy is feasible and has a higher
rate of PCa detection than does repeat TRUS-guided biopsy.
MR-guided biopsies of the prostate are becoming more and
more available, but there is currently no consensus on the
optimal technique.
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EUROPEAN UROLOGY 59 (2011) 962–977
[()TD$FIG]
Fig. 3 – Patient (age: 68 yr) with a prostate-specific antigen level that has increased to 28 ng/ml (in 2010) from 8.5 ng/ml (in 2006); digital rectal
examination identified no suspicious areas. Between 2006 and 2010, four 10-core transrectal ultrasound biopsies were performed with negative
histologic results. Magnetic resonance (MR)-guided biopsy revealed a Gleason 7 (4 + 3) prostate adenocarcinoma. (A) Axial T2-weighted MR image
demonstrates homogeneous low signal intensity area (oval) of lenticular shape in the left ventral prostate, which shows restriction on (B) the apparent
diffusion coefficient map, and (C) increased enhancement on the dynamic contrast-enhanced MR image. (D) MR-guided biopsy from the same region
(red). The needle is indicated in white.
In conclusion, in the initial diagnosis of PCa, the use of
multiparametric MRI combining T2W imaging, MRSI,
DCE-MRI, and DWI can potentially reduce the rate of
false-negative biopsies and decrease the need for more
extensive or repeat biopsy procedures by allowing
biopsies to be targeted with substantial specificity and
sensitivity.
3.2.3.
Clinical relevance and potential limits of magnetic resonance
imaging in the initial diagnosis
The level of evidence to support the use of multiparametric
MRI in the initial diagnosis of PCa is particularly significant
in cases with persistently elevated PSA levels and previous
negative biopsies. Different prospective studies and one
randomised study [14,18,19] have been conducted.
Of the available multiparametric MRI techniques, T2W
MRI, DWI, and DCE-MRI are, at present, the most practical
and relevant for clinical practice. The use of MRI for
directing targeted biopsies is limited by the difficulties of
merging multiparametric MRI with real-time TRUS to
direct TRUS-guided biopsies and the lack of equipment
for MR-guided biopsy at most centres.
3.3.
Oncologic and functional implications in the planning of
radical prostatectomy
To obtain the best results with RP, from either an oncologic
or functional point of view, meticulous preoperative
selection of cases and planning of surgery are crucial. Often
used for treatment selection and planning are predictive
instruments such as nomograms, which typically include
PSA and pathologic findings at biopsy [1,24]. Imagingderived preoperative information concerning the risk of
extracapsular disease and the locations of tumour foci in the
prostate can help clinicians select and plan surgical
treatment appropriately (Table 3).
3.3.1.
Preoperative local staging
The literature shows a wide range (50–92%) in the accuracy
of local staging by MRI [17]. It has been suggested that the
addition of volumetric data from MRSI or DCE-MRI to MRI
significantly improves local staging and, in particular,
reduces interobserver variability [17]. However, the findings still need to be validated in larger studies. Seiz et al, in
their collaborative review article [8], underlined that
EUROPEAN UROLOGY 59 (2011) 962–977
Table 3 – Planning for radical prostatectomy
Actual diagnostic tools
What MRI could offer
Potential limits of MRI
Prostate-specific antigen
Gleason score
Biopsy results
Nomograms
Identification of real clinical T2 cases
Mapping of tumour sites in the prostate
Relationship between tumor and NVBs
NVB status after radical prostatectomy
Early identification of local recurrence
Possible artefacts due to structure
modification after the biopsy or the
surgical procedure
MRI = magnetic resonance imaging; NVB = neurovascular bundle.
[()TD$FIG]
sensitivity, specificity, and accuracy in tumour staging were
higher with DCE-MRI than with MRSI. In a limited
population of 64 cases, Kim et al. [25] analysed the role
of a combined DWI and DCE-MRI technique (at 1.5T) in
predicting the local stage, using pathologic results obtained
at RP as the reference standard. In detecting extraprostatic
extension, the combination of DWI and DCE-MRI displayed
82.4% sensitivity, 87.2% specificity, 70% PPV, and 93.2% NPV.
Higher values (92.3%, 93.1%, 85.7%, and 96.7%, respectively)
were found when only cases with clinically high-risk
disease features (cT3, PSA 20 ng/ml, or Gleason score
8) were analysed. In 158 patients with clinical stage T1c
967
disease, Zhang et al. [26] analysed the role of preoperative
combined MRI/MRSI (at 1.5T) in predicting the pathologic
stage of PCa. The overall accuracy of PCa staging by MRI/
MRSI was 80%; staging accuracy was highest for the
smallest tumour volumes (91% for tumour volumes
<0.5 cm3 vs 75% for tumour volumes >2.0 cm3). In the
detection of extracapsular disease, MRI/MRSI had an AUC of
0.74. In a limited population of 27 patients considered for
RP, Augustin et al. [27] compared the accuracy of 3T MRI
with the Partin tables in predicting pathologic stage. In the
detection of extracapsular extension, MRI had an accuracy
of 85.2%, sensitivity of 66.7%, and specificity of 100%. The
Spearman r for correlation with extracapsular extension
was higher for MRI findings (0.780) than for the Partin
tables (0.363). Overall, 3T MRI was significantly more
accurate than the Partin tables in predicting the final
pathologic stage.
3.3.2.
Preoperative localization and mapping of tumour foci
Better characterization of PCa is necessary to improve
surgical, oncologic, and functional outcomes. MR techniques can provide needed information about the location
and size of PCa, as well as its relationship to prostatic and
extraprostatic structures (Fig. 4).
Katahira et al studied 201 patients with PCa who
underwent DWI before RP [28]. Each prostate was divided
Fig. 4 – Patient (age: 65 yr) with a prostate-specific antigen level of 9.5 ng/ml; digital rectal examination identified no suspicious areas; transrectal ultrasoundguided biopsy showed prostate adenocarcinoma Gleason 6 (3 + 3) in left and right samples. Histology at radical retropubic prostatectomy showed a Gleason
6 (3 + 3) tumour with Gleason 7 (4 + 3) focal hot spots (pT2b). (A) Axial T2-weighted magnetic resonance image (MRI) shows low signal intensity tumour in
peripheral zones (PZ) (white area). (B) Axial dynamic contrast-enhanced MRI shows increased contrast leakage in tumour and benign prostatic hyperplasia
areas. (C) Axial apparent diffusion coefficient (ADC) map from diffusion-weighted imaging shows low signal throughout the entire tumour, with two focal
low signal intensity hot spots (yellow areas). These findings may reflect the fact that the tumour is predominantly Gleason score 6 (3 + 3), with focal areas of
Gleason score 7 (4 + 3). (d) Histopathology map after radical retropubic prostatectomy shows Gleason 6 (3 + 3) prostate cancer (PCa) area identical to the low
signal intensity area in (A), and Gleason 7 (4 + 3) PCa in focal hot spots identical to areas of restrict diffusion on ADC map in (C).
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EUROPEAN UROLOGY 59 (2011) 962–977
[()TD$FIG]
into eight segments; on the basis of 1.5T MRI results, the
probability of the presence of PCa in each segment was
estimated using a five-point rating scale. Results were
compared with those of whole-mount, step-section, histopathologic examination. The sensitivity, specificity, and
AUC of DWI for the localization of PCa were 73%, 89%, and
0.842, respectively. In a study of 83 patients who underwent
RP, Puech et al. [29] analysed the performance of DCE-MRI
(at 1.5T) in identifying and localizing intraprostatic cancer
foci in relation to cancer volume at histology. At MRI, the
prostate was divided into eight segments and results scored
on a five-point scale. The sensitivity and specificity of DCEMRI for identification of PCa foci of any volume were 32%
and 95%, respectively. For identification of cancer foci
>0.5 ml, the sensitivity and specificity were 86% and 94%,
respectively, and the AUC was 0.874. In their study of 158
patients with clinical stage T1c PCa, Zhang et al. [26]
assessed the accuracy of MRI/MRSI in predicting PCa in 12
prostate regions, using whole-mount, step-section pathologic maps as the reference standard. The results of
combined MRI/MRSI were relevant, but their accuracy did
not differ significantly among the different areas of the
prostate (AUC = 0.71 for the base, 0.61 for the midgland, and
0.69 for the apex). Weinreb et al. [30] published the results
of a prospective multicentre study conducted by the
American College of Radiology Imaging Network to assess
the incremental value of MRSI to MRI in the sextant
localization of peripheral-zone PCa. Authors analysed
imaging results for 134 patients with PCa who underwent
combined MRI/MRSI at 1.5T. Eight readers independently
rated the likelihood of the presence of PCa in each prostate
sextant by using a five-point scale, and histopathologic
results at RP were used as the reference standard. The
accuracy of combined MRI/MRSI (AUC = 0.58) was equivalent to that of MRI alone (AUC = 0.60). This negative result
for MRSI may have been partly related to the fact that the
study population consisted predominantly of patients with
low-risk, small-volume disease: Most of the cases were
clinical stage T1c, the mean PSA was 5.9 ng/ml, and the
mean tumour volume was 2.75 cm3.
3.3.3.
Functional evaluation
The decision to preserve or resect the neurovascular
bundles (NVBs) at RP is often difficult and based on
preoperative clinical characteristics and intraoperative
findings. MRI techniques can help predict the absence of
tumour in the areas of the NVBs (Fig. 5). In a study of 75
patients with PCa scheduled for RP, Labanaris et al. [31]
analysed the value of conventional and functional 1.5T MRI
in predicting the risk of extracapsular extension in relation
to NVBs. Cases were considered appropriate for nervesparing surgery if the tumour did not extend outside the
capsule in the posterolateral region of the prostate as
assessed by imaging. Based on MRI findings, the operative
strategy was changed in 44% of cases. Among these, the
findings favoured NVB preservation in 67% of cases with
high clinical probability of extracapsular extension and
opposed NVB preservation in 33% of cases with low clinical
probability of extracapsular extension. Based on the final
Fig. 5 – Sexually active 48-yr-old man with prostate-specific antigen level
of 9 ng/ml; digital rectal examination identified no suspicious areas;
transrectal ultrasound-guided biopsy showed prostatic adenocarcinoma
Gleason 7 (4 + 3) in samples from the right side. The patient underwent
nerve-sparing radical retropubic prostatectomy. (A) Axial T2-weighted
magnetic resonance image shows low signal intensity tumour in right
peripheral zone (PZ) (white area) with obliteration of the white fat at the
rectoprostatic angle (arrows) indicating minimal extracapsular
extension (ECE). The neurovascular bundle is indicated by red, blue, and
yellow. (B) Pathologic examination of the surgical specimen showed
Gleason score 7 (4 + 3) prostate adenocarcinoma with submillimeter ECE
(T; blue area) in the right PZ. Resection margins were negative.
histopathologic findings, the sensitivity, specificity, and
accuracy of MRI in predicting seminal-vesicle invasion,
extracapsular extension, or NVB involvement, and thereby
obtaining a correct preoperative decision, were 92%, 100%,
and 100%, respectively. In a population of 62 patients who
underwent RP, Brown et al. [32] evaluated the impact of
preoperative staging with 1.5T MRI on NVB-sparing
aggressiveness and surgical margin positivity. They concluded that unenhanced MRI is of limited usefulness in
detecting extracapsular extension and therefore carries the
risk of leading to inappropriate nerve-sparing surgery and
possible positive surgical margins. MRSI, DWI, and DCE-MRI
were not performed in the study.
The probability of recovering erectile function after RP is
associated inversely with patient age and comorbidity, and
directly with the extent and number of NVBs preserved. In
patients reported to have undergone nerve preservation,
poor recovery of erectile function after surgery raises
several questions. In a study of 53 patients with PCa who
EUROPEAN UROLOGY 59 (2011) 962–977
[()TD$FIG]
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Fig. 6 – Sexually active 61-yr-old man (preoperative International Index of Erection Function Five-Item [IIEF-5] questionnaire score = 23). Nerve-sparing
radical retropubic prostatectomy (RRP) revealed intracapsular (pT2a) Gleason score 7 (3 + 4) prostate adenocarcinoma in the right peripheral zone (PZ);
surgical margins were negative. The postoperative IIEF-5 score was 16. (A) Pre-RRP T2-weighted image. Note the distance between the lesion (outlined in
white), capsular profile (outlined in yellow), and right neurovascular bundle (NVB) (blue, red, and yellow points). (B) Pre-RRP evaluation: Diffusion tensor
(DT) imaging shows the right NVB course (green area) tangent to capsular profile. (C) Pre-RRP evaluation: Three-dimensional (3D) T2-weighted isotropic
image shows the same findings on the right side and the presence of a fat-tissue plane between the capsular profile and the left NVB course (arrows).
(D) Post-RRP evaluation: 3D T2-weighted isotropic image shows normal course and signal intensity of left NVB (arrows). (E) Post-RRP evaluation: 3D T2weighted isotropic image shows irregular aspect with multiple small injuries on right NVB (arrows). (F) Post-RRP evaluation: DT image confirms partial
damage to the right NVB.
underwent bilateral nerve-sparing RP, Sciarra et al. [33]
analysed the capability of a dedicated 3D, isotropic, MRI
T2-weighted sequence to depict postsurgical changes in the
NVBs. Postoperative MRI examinations were compared
with the International Index of Erection Function five-item
(IIEF-5) questionnaire, which served as the reference
standard. The authors developed a relative five-point
system for classifying MRI findings on the basis of anatomic
course delineation for each or both NVBs. In all cases the
correlation and regression analysis between MRI and IIEF-5
findings resulted in high coefficient values (r = 0.45;
p = 0.001).The imaging protocol and the NVB-change
classification system proposed in this study can be applied
successfully as early as 40 d after RP. Together, they could
provide an additional diagnostic tool in the postoperative
evaluation and treatment of erectile dysfunction (Fig. 6).
3.3.4.
Early detection of local recurrence after radical prostatectomy
The crucial point in the evaluation of biochemical progression after RP is the differentiation between local and distant
disease. Often this evaluation is based on clinical parameters (PSA, PSA doubling time, and the interval between
surgery and PSA relapse), pathologic stage, resection
margins and grade at surgery, or nomograms. Casciani
et al. [34] analysed a limited population of 51 PCa patients
with biochemical progression after RP who underwent MRI
and DCE-MRI (1.5T MRI) before TRUS-guided biopsy of the
prostatic fossa. When compared with biopsy results, MRI
alone achieved an accuracy of only 48%; combined MRI/
DCE-MRI had an accuracy of 94%. Cirillo et al. [35] analysed
the roles of MRI and DCE-MRI (at 1.5T) for diagnosing local
recurrence of PCa in 72 patients with biochemical progression (mean PSA = 1.23 ng/ml) after RP. Imaging results were
compared with prostatectomy-bed biopsy findings or PSA
reduction after RT. Sensitivity, specificity, PPV, NPV, and
accuracy were 61.4%, 82.1%, 84.4%, 57.5%, and 69.4%,
respectively, for unenhanced MRI, and 84.1%, 88.3%,
92.5%, 78.1%, and 86.1%, respectively, for DCE-MRI. Sciarra
et al. [36] analysed findings from combined MRSI and DCEMRI (at 1.5T) in 70 PCa patients with biochemical
progression after RP. The reference standard was a
biopsy-proven cancer recurrence (mean PSA = 1.26 ng/ml)
in 50 patients and a reduction in PSA level >50% following
RT (mean serum PSA = 0.8 ng/ml) in 20 patients. The
sensitivity, specificity, PPV, and NPV of combined MRSI
and DCE-MRI were 87%, 94%, 96%, and 79%, respectively, in
the first group, and 86%, 100%, 100%, and 75%, respectively,
in the second group. Receiver operating characteristic
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EUROPEAN UROLOGY 59 (2011) 962–977
analysis showed that MRSI performed less well in the
second group than in the first group; this difference may
reflect the fact that the required voxel size for spectroscopic
imaging is larger than that for DCE-MRI, an issue that may
be especially relevant in patients with small-volume
disease, such as the second group in the Sciarra et al study.
These analyses suggest that the use of combined MRSI
and DCE-MRI can improve the detection of local recurrence
after RP, including in patients with low PSA values and lowvolume recurrence (Fig. 7).
3.3.5.
Clinical relevance and potential limits of magnetic resonance
imaging in radical prostatectomy planning
The level of evidence to support the use of multiparametric
[()TD$FIG]MRI in this field starts to be significant, particularly for
preoperative localization and mapping of the tumour and
an early diagnosis of local recurrence. Different prospective
studies on a significant population have been presented
(26,28–30,35,36). The possibility of improving the planning
of a nerve-sparing RP, combining an oncologic and
functional evaluation, is also clinically suggestive. A 3T
MRI evaluation can be sufficient, but the combination of at
least two (DCE-MRI and MRSI) multiparametric techniques
can improve results, particularly for an early diagnosis of
local recurrence [36]. In addition, MRSI and DWI can
distinguish the presence of recurrence from healthy
residual prostate tissue. Limitations are mainly related to
possible artefacts due to structure modification after the
biopsy or the surgical procedure that can influence a correct
analysis of the prostate or of a possible recurrence.
Fig. 7 – Patient (age: 58 yr) with prostate-specific antigen (PSA) progression, from 0.1 to 0.7 ng/ml, 8 mo after radical retropubic prostatectomy (RRP). At
RRP, prostatic adenocarcinoma of Gleason 7 score (4 + 3) and stage pT2b was found. Locally recurrent prostate cancer was confirmed on the basis of a PSA
decrease (PSA = 0.1 ng/ml) after external beam radiation therapy. (a) T2-weighted magnetic resonance imaging (MRI) shows 5-mm intermediate signal
intensity nodule (arrow) in a perianastomotic location. (b) MR spectroscopic imaging analysis with reference images on the nodule shows two
consecutive voxels with reduced citrate (Ci) signal and increased choline (Cho) plus creatine (Cr) to citrate ratio (>1). (c) Dynamic contrast-enhanced
(DCE) MRI shows a hypervascular lesion (arrow) and malignant patterns. (d) DCE-MRI intensity/time curve of the same area shown in (c) demonstrates a
hypervascular lesion. (e) Axial diffusion-weighted imaging shows restriction (high signal intensity on T2 native image) of the nodule.
EUROPEAN UROLOGY 59 (2011) 962–977
Table 4 – Planning for external-beam radiation therapy
Actual diagnostic tools
What MRI could offer
clinicians
Potential limits of MRI
Prostate-specific antigen
Computed tomography scan
Transrectal ultrasound-guided biopsy
Nomograms
Mapping of the prostate for tumor
sites
Guide for RT performance
Definition and follow-up of RT response
Early identification of local recurrence
Possible artefacts due to structure
modification during RT
MRI = magnetic resonance imaging; RT = radiation therapy.
3.4.
Oncologic implications in the planning of radiation therapy
Treatment of PCa with external RT has evolved. However, it
is known that poor treatment coverage at RT is associated
[()TD$FIG]with an increased risk of local and distant progression [37].
971
The major obstacle to achieving sufficient coverage is the
limited ability of CT, the modality typically used for RT
planning, to delineate tumour (Table 4). In patients
undergoing external-beam radiation therapy (EBRT), three
possible indications for MRI techniques have been considered: (1) localization of the tumour before and during RT,
(2) prediction of the risk of progression after RT, and (3)
detection of local recurrence after RT.
3.4.1.
Localization of the tumour before and during radiation
therapy
Before RT, MRI has much greater soft-tissue contrast
than CT and better delineates the extent of PCa in the
prostate and periprostatic structures, especially at the
apex close to the bulb of the penis. This leads to a more
accurate delineation of the irradiation field, which allows
reduction of the dose to the periprostatic tissue and
urethra, along with delivery of the maximum dosage to
Fig. 8 – Patient (age: 69 yr) with prostate-specific antigen (PSA) progression (PSA = 2.0 ng/ml) 3 yr after external-beam radiation therapy (RT) (primary
prostatic adenocarcinoma: Gleason score 7 (4 + 3), right peripheral zone [PZ]). Magnetic resonance imaging (MRI) and transrectal ultrasound (TRUS)guided biopsy of this area confirmed Gleason score 8 (4 + 4) recurrence after RT at right PZ (same primary tumour location). (A) Axial T2-weighted MRI
shows low signal intensity in the prostate due to previous RT. Therefore, tumour (arrow) is difficult to see. At arrow there is some bulging. (B) Axial
dynamic contrast-enhanced MRI shows increased contrast leakage at right PZ (circle) that is highly suspicious for prostate cancer. (C) Axial apparent
diffusion coefficient map from diffusion-weighted imaging shows restriction (low signal intensity) (circle). TRUS-guided biopsy of this area confirmed
Gleason score 8 (4 + 4) recurrence.
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EUROPEAN UROLOGY 59 (2011) 962–977
the target within the prostate [37]. The recent literature
does not include any relevant studies on the use of
MRI parameters for monitoring tissue changes during RT
[38].
3.4.2.
Prediction of the risk of progression
McKenna et al. [39] suggested that pretreatment endorectal
MRI findings are predictive of outcomes after external RT. In
a study of 40 patients with PCa, they showed that the mean
diameter of extracapsular extension was an independent
predictive variable for progression (hazard ratio [HR] =
2.06; 95% confidence interval [CI], 1.22–3.48). They also
suggested that patients with extracapsular extension
>5 mm on MRI may be potential candidates for more
aggressive therapies, such as radiation dose escalation or
combining therapy with androgen deprivation. In a study of
67 men who underwent EBRT for PCa, Joseph et al. [40]
showed that preoperative evaluation of 1.5T MRSI data
could be used to predict outcomes after RT. In particular, the
volume of malignant metabolism on MRSI was an
independent predictor of biochemical failure (HR = 1.63;
95% CI, 1.29–2.06; p < 0.001).
[()TD$FIG]
Fig. 9 – Patient (age: 67 yr) with prostate-specific antigen level of 15 ng/ml; histology at biopsy showed prostatic adenocarcinoma of Gleason score 6 (3 + 3)
in the right peripheral zone (PZ). The patient chose high-intensity focussed ultrasound (HIFU) treatment. (a) Pretreatment axial dynamic contrastenhanced (DCE) magnetic resonance imaging (MRI) (arrow); (b) perfusion map, and (c) intensity/time curve show pathologic enhancement in the right
PZ. (d–f) At MR spectroscopic imaging, the spectrum of metabolites shows an increase of choline (circles on spectra) in the same site combined with an
increase of creatine (rectangle in [e]); the pattern is consistent with tumour-associated prostatitis. (g) Post-HIFU (1 mo) analysis: axial DCE-MRI, (h)
perfusion map, and (i) intensity/time curve show absence of angiogenesis and a wide zone of coagulative necrosis.
973
EUROPEAN UROLOGY 59 (2011) 962–977
3.4.3.
Detection of local recurrence after radiation therapy
After RT, the prostate is characterised by a diffuse low
signal. For this reason, MR T2W imaging is less helpful in
localizing PCa recurrence (Fig. 8). In a limited population of
64 patients who underwent EBRT for PCa, Westphalen et al.
[37] compared the role of combined MRI/MRSI with MRI (at
1.5T) alone in detecting local recurrence. Results from
TRUS-guided biopsies were used as the reference standard.
The combined MRI/MRSI analysis, when compared with
MRI alone, had a greater percentage of true-positive results
(59% vs 41%) without an important change in the percentage
of false-positive results (10% vs 7%). Therefore, the addition of
MRSI to T2W MRI alone significantly improved the detection
of local recurrence after RT.
Studies evaluating DCE-MRI after RT report sensitivities
of 70–74% and specificities of 73–85% [41]. In 172 patients
with PCa treated with EBRT, Kara et al. [42] compared the
role of DCE-MRI (1.5T MRI) with TRUS in follow-up (18 mo
from RT). Using biopsy results as the reference standard, the
sensitivity and specificity of TRUS in the detection of
tumour recurrence after RT were 53.3% and 60%, respectively. The sensitivity and specificity of T2W MRI were 86%
and 100%, respectively; the sensitivity and specificity of
DCE-MRI were 93% and 100%, respectively. DCE-MRI was
significantly more accurate than T2W MRI for the detection
of PCa recurrence after RT.
3.4.4.
Clinical relevance and potential limits of magnetic resonance
imaging in radiation therapy planning
The level of evidence to support the use of multiparametric
MRI in this field is still low and further prospective studies are
necessary. Multiparametric MRI is very accurate in showing
normal and abnormal prostate tissue and therefore could
be important for enabling optimal intensity-modulated RT
planning. Although T2W and DWI MRI are limited in the
detection of local recurrence after RT, DCE MRI or MRSI can be
used to accurately identify the presence of such recurrence
[37,42].
Limitations are mainly related to possible artefacts due to
structure modification during RT that can influence a correct
analysis of treatment response or recurrence identification.
3.5.
Oncologic implications in the planning of focal therapies
Besides RP and EBRT, different focal therapies, such as
brachytherapy (a well-established treatment for PCa),
cryosurgical ablation, and high-intensity focussed ultrasound (HIFU), have emerged as alternative therapeutic
options in patients with PCa [1]. The efficacy and safety of
these procedures are strongly influenced by the accuracy of
PCa localization and tumour volume prediction [43]. A
second important issue is the ability to characterise
morphologic changes induced by focal therapies inside
the tumour mass to better assess treatment efficacy in the
individual patient (Table 5). Multiparametric MRI has the
potential to localise primary or recurrent PCa accurately, to
describe tumour volume, and to show morphologic changes
during and after treatment (Figs. 9 and 10) [44]. Changes in
MRSI findings during different focal therapies have been
Table 5 – Planning for focal therapies
Actual diagnostic
tools
What MRI could
offer clinicians
Potential limits
of MRI
Prostate-specific antigen
Computed tomography scan
Transrectal ultrasound-guided biopsy
Nomograms
Mapping of the prostate for tumor sites
Guide for focal therapy performance
Definition and follow-up of focal therapy response
Early identification of local recurrence
Possible artefacts due to structures modification
during focal therapies
MRI = magnetic resonance imaging.
described: An initial phase with an increase in choline or in
all metabolites detected has been reported, and a second
phase of metabolic atrophy (ie, detection of no metabolites)
has been considered evidence of complete response [43].
With DWI, a reduction of ADC is considered the most
important signifier of local recurrence after focal treatment;
however, fibrosis can produce similar ADC values, limiting
the usefulness of DWI in the evaluation of focal therapy
[43]. DCE-MRI shows changes in vascularisation and
contrast enhancement that correlate well with inflammation, necrosis, devascularisation, and fibrosis induced by
focal therapies [43].
Three possible indications for MRI techniques in patients
undergoing focal therapies have been suggested: (1)
localisation and identification of the tumour before treatment, (2) guidance of focal treatment, and (3) identification
of morphologic changes as measures of response.
However, to date, most published studies have focussed
primarily on the feasibility of using MRI in the setting of
focal therapy rather than on results in terms of oncologic
control, and data are very limited.
3.5.1.
Brachytherapy
Transperineal brachytherapy is considered a safe and effective
technique mainly for the treatment of localised (cT1b-T2a),
low-risk (Gleason score 6, PSA <10 ng/ml, <50% of biopsy
cores involved) PCa [1]. It is performed under TRUS guidance,
and a prostate volume <50 cm3 is considered necessary for
successful implantation [1]. The benefits of image-guided
brachytherapy using MRI and the feasibility of targeting the
peripheral zone with good dosimetric coverage have been
described [45]. In brachytherapy, the current standard for
post-plan dosimetry is CT imaging performed either immediately after the procedure or 1 mo later. In a cohort of 131 men
receiving iodine-125 prostate brachytherapy, Crook et al. [46]
used 1.5T MRI at 1 mo postimplantation to determine the
treatment margins. They reported satisfactory use of MRI to
cover a 2- to 3-mm periprostatic margin. Similarly, Acher et al.
[47] compared 1.5T MRI with CT as a method for the
dosimetric analysis of permanent prostate brachytherapy
implants. In 30 cases, four observers agreed significantly more
closely on the prostate base and apex positions, as well as the
outlining contours, when reading MR images than when
reading CT images. These studies suggest that MRI-based
dosimetry offers an alternative to CT-based dosimetry,
allowing better prostate delineation and more confident 3D
reconstruction of the implant.
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EUROPEAN UROLOGY 59 (2011) 962–977
[()TD$FIG]
Fig. 10 – Patient (age: 48 yr) with prostate adenocarcinoma Gleason score 7 (4 + 3). The patient chose magnetic resonance (MR)-guided focal laser ablation
(Visualase) (Visualase Inc, Houston, TX, USA). (A) Apparent diffusion coefficient map shows restriction in transition zone (TZ), which proved to represent a
Gleason score 7 (4 + 3) prostate cancer on MR-guided biopsy. (B) Interactive MR temperature map image during laser ablation procedure, showing the
killing zone in orange (>67 8C). (C) Posttreatment contrast-enhanced MR image shows the area of destruction (red arrows), which matches the tumour
area in (A) and the killing zone in (B). Procedure was performed using an in vivo MR-biopsy device (image courtesy of John F Feller, Desert Medical
Imaging, Indian Wells, CA, USA).
3.5.2.
High-intensity focussed ultrasound
In a study of 10 patients, Cirillo et al. [48] assessed the roles
of MRI and MRSI (1.5T MRI) in evaluating changes in the
prostate after HIFU for PCa, correlating imaging findings
with histology at biopsy. At 4 mo, there was a statistically
significant difference ( p = 0.015) between patients responding to treatment and those with persistent disease by
combining negative MRI with PSA level <0.5 ng/ml. MRSI
data were suitable for analysis only in three cases with partial
necrosis and provided no additional value.
In a study of 15 patients treated with HIFU for PCa, Ben
Chiekh et al. [49] used T2W MRI and DCE-MRI at 1.5T for the
detection of local tumour recurrence. At biopsy, tumour
recurrence was found in 13 of 15 cases. On T2W MRI,
the treated prostate tissue was diffusely hypointense,
which interfered with interpretation. Only 3 cases had
suspicious areas at MRI, whereas all 15 cases had
suspicious areas at DCE-MRI. Sensitivity, specificity, PPV,
and NPV of T2W MRI were 0.13, 0.98, 0.60, and 0.81,
respectively, and 0.70, 0.85, 0.55, and 0.91, respectively, for
DCE-MRI. DCE-MRI was strongly predictive of positive
biopsy results, but T2W MRI was not. Kim et al. [50] used
DCE-MRI and the combination of T2W MRI and DWI (1.5T
MRI) in 27 patients with increased PSA levels after HIFU.
Biopsy detected local tumour progression in 54 (33%) of
162 sextants in 18 cases. Sensitivity, specificity, and
accuracy values achieved by two independent readers
were 80–87%, 63–68%, and 71–72%, respectively, with
DCE-MRI, and 63–70%,74–78%, and 73%, respectively, with
combined T2W MRI and DWI.
3.5.3.
Cryotherapy
The literature search did not reveal any articles on the use of
MRI in patients undergoing cryotherapy for PCa.
EUROPEAN UROLOGY 59 (2011) 962–977
3.5.4.
Clinical relevance and potential limits of magnetic resonance
imaging in focal therapies planning
975
diagnoses will lead to more effective and tailored therapies
with lower costs.
The level of evidence to support the use of multiparametric
MRI in this field is still low, and only the feasibility has been
demonstrated.
Author contributions: Alessandro Sciarra had full access to all the data in
4.
Study concept and design: Sciarra.
Conclusions
the study and takes responsibility for the integrity of the data and the
accuracy of the data analysis.
Acquisition of data: Sciarra.
The standard tests and predictive models that clinicians use
to choose diagnostic and therapeutic strategies for PCa have
considerable limitations, and a valid imaging tool is needed
to improve all stages of PCa management. Published data
indicate an emerging role for MRI (particularly multiparametric MRI combining T2W imaging, DWI, DCE, and
MRSI) as the most sensitive and specific tool available for
imaging PCa. Multiparametric MRI can provide metabolic
information; characterise tissue and tumour vascularity, as
well as tissue cellularity and integrity; and correlate with
tumour aggressiveness [51]. It appears to be the most
accurate imaging method for localising primary PCa and
staging primary or recurrent PCa.
The available literature suggests that multiparametric
MRI is helpful and clinically relevant for the following tasks
at minimum: (1) detection of PCa in patients with previous
negative prostate biopsies and persistently elevated serum
markers, in whom it reduces the need for additional and
more extensive biopsies and identifies suspicious areas for
targeted sampling; (2) characterization of PCa to facilitate
appropriate treatment selection; and (3) early identification
of local recurrence in patients with biochemical recurrence
after primary therapy. Two other potential applications
of MRI for PCa include MR-guided prostate biopsy and MRguided focal therapy; however, for these, only feasibility has
been demonstrated and data on the significance of clinical
results are needed.
Larger multicentre studies are needed to confirm the
initial promising results and validate the use of multiparametric MRI for all the indications previously discussed
here. Before such studies can be performed, however, more
research is needed to standardise imaging protocols and
determine reproducible quantitative parameters and
thresholds for identifying and evaluating PCa with multiparametric MRI.
The development of prostate MRI has been limited by
obstacles to its dissemination and implementation.
Although MRI of the prostate can be mastered [52],
experienced radiologists who are trained appropriately to
read it are still lacking. Furthermore, even in centres
where MRI technology is present, its availability for PCa
imaging is often limited. Pressure from referring physicians (eg, urologists, radiation oncologists, and medical
oncologists) is needed to ensure the availability of MRI
expertise, as well as MRI time, for the indications noted in
this review.
Finally, efforts to evaluate the cost effectiveness of
multiparametric MRI will also be needed. Although there
are no recent studies on this topic, it seems likely that the
use of multiparametric MRI to achieve more accurate initial
Analysis and interpretation of data: Barentsz, Bjartell, Eastham, Hricak,
Panebianco, Witjes.
Drafting of the manuscript: Sciarra.
Critical revision of the manuscript for important intellectual content:
Barentsz, Bjartell, Eastham, Hricak, Panebianco, Witjes.
Statistical analysis: None.
Obtaining funding: None.
Administrative, technical, or material support: None.
Supervision: Barentsz, Bjartell, Eastham, Hricak, Panebianco, Witjes.
Other (specify): None.
Financial disclosures: I certify that all conflicts of interest, including
specific financial interests and relationships and affiliations relevant
to the subject matter or materials discussed in the manuscript
(eg, employment/affiliation, grants or funding, consultancies, honoraria,
stock ownership or options, expert testimony, royalties, or patents filed,
received, or pending), are the following: None.
Funding/Support and role of the sponsor: None.
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