Diagnostic ultrasound ( PDFDrive )

410 PART II Abdominal and Pelvic Sonography
S
S
S
M
S
L
S
S
L
+
L
S
T
T
S
L
L
S
S
L
L
S
S
L
Initial
10 core + target
Extended
13 core
FIG. 10.19 Biopsy Sites as Viewed en Face From Posterior Aspect of Prostate. Left image shows the standard 10 prostate biopsy sites.
Additional samples are taken of any lesion that is evident outside the systematic pattern (+). Right image shows a typical extended pattern of
biopsies, in this case a 13-core pattern. In addition to the sextant sites (S), samples are taken from the lateral peripheral zones (L), deep in the
anterior transition zone (T), and from the peripheral zone in the midline (M) at the base, cephalad to the verumontanum. L, lateral or “anterior horn”;
S, sextant.
Systematic samples are obtained from the peripheral zone at
the base, middle, and apex of the gland both medially and laterally
from each lobe. 25,26,135,142,143 Some term this patterned approach
as “random biopsy” or “blind biopsy.” It is neither random nor
blind, but rather sampling follows a speciic systematic pattern
along with a search for suspicious targets. It is important that
the lateral samples include the “anterior horns” (part of peripheral
zone that curves anteriorly around the sides of the transition
zone) and the apical peripheral zone. Others have found that
both medial and lateral samples are equally important, and that
it remains important to search for hypoechoic nodules. 153,155 his
approach should result in an overall 30% to 60% positive biopsy
rate, and about a 60% or higher yield for lesions that are suspicious
at ultrasound. 135 Although TRUS biopsy is the established and
currently recommended procedure for the initial biopsy because
of its simplicity and cost-efectiveness, there is emerging enthusiasm
to consider mpMRI before the irst biopsy. 156,157 Optimistic
reports from a highly experienced luminary center in biopsy-naïve
patients showed overall cancer detection with TRUS of 57%,
with 37% being low grade. In contrast, mpMRI in bore biopsy
yielded 70% cancer, of which only 6% was low grade. By relying
on mpMRI indings, these researchers estimated a decrease in
biopsy rate of 51% and an 81% decrease in low-risk cancer
detection. Nonetheless, follow-up of negative biopsy was still
recommended. 158 Reviews of published reports ind little diference
between TRUS and MRI for initial biopsy and suggest that,
currently, systematic TRUS biopsy may suice for irst biopsy
and that there is still need for research and training before
restricting biopsy only to mpMRI targets because systematic
TRUS biopsy detects signiicant cancer in about 12% of men
with negative mpMRI indings. 159
About 20% to 30% of men with initial negative biopsy have
cancer that was missed. he box lists indications for repeat or
additional biopsy. Following negative initial biopsy, some have
suggested that ater four negative repeat sessions the yield is
only 4%, but others ind a continued cancer yield of about 15%
on each repeat.
Timing of the repeat biopsy varies with clinical indications
and pathologic indings at initial biopsy. In low-risk cancer patients
opting for active surveillance, an initial conirmatory repeat is
suggested in 3 to 18 months and then follow-up as per local
protocols. Atypical small acinar proliferation (ASAP) is found
in about 4% (1%-23%) of biopsies. Many pathologists believe
that ASAP is a minute cancer focus and may represent either a
tiny tumor or possibly a few cells from the margin of a larger
adjacent tumor. Repeat biopsy is recommended in 3 to 6 months
and yields cancer in about 40%. Multifocal high-grade prostate
intraepithelial neoplasia (HG-PIN) is found in about 5% (0%-
25%). It is a histologic abnormality found in association with
cancer but not necessarily leading to cancer. With multifocal
HG-PIN, repeat biopsy is suggested in 1 year and cancer yield
is about 40%. Repeat biopsy is not recommended for unifocal
HG-PIN unless clinical indings are worrisome. 26,142,143
here is no generally accepted protocol for sample sites at
repeat biopsy, but most recommend repeating the systematic
12-core biopsy and adding about four additional transition zone
cores (see Fig. 10.19, right).
Most of the cancers will be found in the original systematic
sites with only a small contribution from the added transition
zone and midline. 114 It is important at repeat to especially evaluate
the anterior ibromuscular area, a common site for large missed
cancers 133 (see Fig. 10.17H–I). Most would not consider transperineal
template biopsy with multiple cores for simple repeat
but would consider it for special situations such as staging for
focal therapy. 26,142,143,160
mpMRI-TRUS Fusion Biopsy
mpMRI is emerging for lesion localization before biopsy, especially
repeat biopsy. At initial biopsy both mpMRI targeted and systematic
12-core approaches have similar cancer detection rates. Targeted