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1.
Introduction
Determining the presence of bone metastasis is important
in the management of prostate cancer. It not only represents
the most common site of initial metastases, but also is a
major cause of morbidity and mortality in patients with
prostate cancer. Therefore, it is crucial to accurately detect
bone metastasis in order to plan the most optimal
management for patients with prostate cancer
[1] .Current-
ly, Tc 99m bone scintigraphy (BS) is recommended by
guidelines as the initial work-up modality for bone
metastasis despite its poor accuracy, because it is widely
available comparedwithmore advancemodalities
[2]. How-
ever, magnetic resonance imaging (MRI) has continuously
been tested for the purpose of detecting bone metastasis
during the past 3 decades and has shown promising results
[3] .Recent studies have shown that axial skeleton MRI,
whole-body MRI, and even routine prostate MRI are
excellent in determining bone metastasis in patients with
prostate cancer
[4–6] .Yet, consensus has not been reached
regarding whether it can replace the role of BS in this
clinical setting or not.
Therefore, we performed a systematic review and meta-
analysis to evaluate the diagnostic performance of contem-
porary MRI for the detection of bone metastasis in patients
with prostate cancer.
2.
Evidence acquisition
The present meta-analysis was written according to the
Preferred Reporting Items for Systematic Reviews and
Meta-Analyses guidelines. The research question for the
purpose of this meta-analysis was formulated based on
the following
[18_TD$DIFF]
Patient Index test Comparator Outcomes
Study design
[19_TD$DIFF]
(PICOS
[20_TD$DIFF]
) criteria
[7]: What is the diagnostic
performance of contemporary MRI (magnetic field
strength 1.5 T) for the detection of bone metastasis in
patients with prostate cancer, as compared with histo-
pathological results or best value comparator (BVC; a
combination of imaging/clinical/biological studies and at
least 6 mo of follow-up)?
2.1.
Literature search
A computerized search of MEDLINE and EMBASE databases
up to January 22, 2017 was performed to identify studies
that were relevant to our research question. The search
query combined synonyms for prostate cancer, MRI, bone,
and diagnostic accuracy as follows: ([‘‘prostat* cancer’’] OR
[‘‘prostat* carcinoma’’] OR [‘‘prostat* neoplasm’’] OR [‘‘pro-
stat* tumor’’]) AND ([bone] OR [skeletal]) AND ([‘‘magnetic
resonance imaging’’] OR [‘‘MR imaging’’] OR [MRI] OR [MR])
AND ([detection] OR [detectability] OR [positivity] OR
[sensitivity] OR [specificity] OR [diagnosis] OR [diagnostic]
OR [accuracy] OR [performance]). Bibliographies of identi-
fied articles were screened to identify additional relevant
studies. The search was limited to studies on ‘‘humans’’
using the ‘‘English’’ language.
2.2.
Study selection
2.2.1.
Inclusion criteria
We included studies that met the following PICOS criteria
(10): (1) patients diagnosed with prostate cancer, (2) MRI
used as the index test for detection of bone metastasis, (3)
histopathology or BVC as the reference standard for
comparison, (4) sufficient information to reconstruct
2 2 contingency tables regarding sensitivity and specific-
ity, and (5) publication type of original articles.
2.2.2.
Exclusion criteria
The exclusion criteria were as follows: (1) study population
of
<
10 patients; (2) study population comprising patients
with tumors other than prostate cancer (however, studies
were included if the diagnostic performance was separately
provided for each type of tumor); (3) review articles,
guidelines, consensus statements, letters, editorials, and
conference abstracts; (4) MRI with a magnetic field strength
of
<
1.5 T; (5) MRI used for the detection of bone metastasis
in prostate tumor, but focusing on topics rather than on
diagnostic accuracy; (6) overlapping patient population;
and (7) insufficient data for the reconstruction of
2 2 tables. In case of an overlapping study population,
the study with the largest study population was included.
Authors of the studies were contacted for provision of
further information when 2 2 tables could not be
reconstructed.
The literature search and study selection process was
independently performed by two reviewers (S.W. and
C.H.S., with 4 yr of experience in performing systematic
reviews and meta-analyses) with consultation from a third
reviewer (S.Y.K.) for reaching a consensus when disagree-
ment was present.
2.3.
Data extraction and quality assessment
The following data were extracted from the selected studies
using a standardized form: (1) patient characteristics—
number of patients, number of patients with bone
metastasis, clinical setting (newly diagnosed vs treated
and risk stratification of bone metastasis according to
clinical criteria), median age and range of patients, prostate-
specific antigen (PSA) level, PSA doubling time, Gleason
score (based on biopsy and radical prostatectomy [RP]
specimens in primary and treated prostate cancer, respec-
tively), and clinical T stage (pathological T stage in post-RP
patients); (2) study characteristics—origin of study
(authors, institution, and duration of patient recruitment),
publication year, study design (prospective vs retrospective,
multicenter vs single center, and consecutive vs noncon-
secutive enrollment), reference standard, interval between
MRI and reference standard, blinding to reference standard,
and characteristics of readers (number and experience);
and (3) MRI characteristics—magnet field strength; scanner
model and manufacturer; coverage of MRI (whole body,
axial skeleton or pelvis [as included in routine prostate
multiparametric MRI]); type of MRI sequences used among
diffusion-weighted imaging (DWI), contrast-enhanced (CE)
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