Diagnostic ultrasound ( PDFDrive )

CHAPTER 10 The Prostate and Transrectal Ultrasound 411
mpMRI approaches require fewer cores to detect signiicant cancer
and avoid detection of many clinically insigniicant cancers, but
still miss some signiicant cancer. At time of repeat biopsy following
prior negative biopsy, MRI guidance increases overall cancer
detection by about 1.62 times over systematic biopsy and should
be considered before repeat biopsy. 159-161 mpMRI is especially
helpful to search sites that are typically not sampled at systematic
12-core biopsy including the transition zone and anterior ibromuscular
area (see Fig. 10.17H–I) Currently there are caveats to
mpMRI use, including need for high-quality MRI or expert readers,
use of standardized PI-RADS 2 reporting formats, deinitions of
what constitutes “signiicant cancer,” costs, and access, but developments
are occurring rapidly in all these areas. 160,162
here are several general methods of MRI guidance: cognitive,
MRI-TRUS fusion, and in-bore biopsy. 163,164 With cognitive
guidance the operator reviews the MRI and uses this knowledge
to target the same areas at TRUS biopsy. his is the easiest and
likely most used approach currently. With MRI-TRUS fusion
biopsy, the MRI images and targets are co-registered and
fused to TRUS images. Biopsy is performed with one of several
available tracking and co-registration devices and is slightly more
sensitive in detection of signiicant cancer than the cognitive
approach. 161,162,165 With in-bore biopsy, the biopsy is carried out
in the MRI gantry.
Transperineal Biopsy and Template Biopsy
Transperineal biopsy is considered for two separate reasons: to
decrease infections and to provide accurate cancer characterization
and mapping for focal therapy and active surveillance. Both can
use freehand approaches or use the same template that is used
in brachyradiotherapy (see Fig. 10.14). Chang and colleagues
have suggested that transperineal biopsy provides more sterile
access to the prostate and avoids concerns of increasing antibiotic
resistance and sepsis. 145,166
Before considering active surveillance or focal therapy, some
have expressed concern that sampling by conventional biopsy
is inadequate to detect and map signiicant disease. In these
cases transperineal template mapping or saturation biopsy under
general anesthesia is performed, taking samples using the
brachytherapy template, which allows 40 to 70 evenly distributed
cores taken 5 mm apart (see Fig. 10.19). Compared with conventional
TRUS biopsy, cancer detection increases to about 70%
from 20% to 40%. Complications are similar to those of TRUS
biopsy, but transient urinary retention is seen in up to 39%. 166
Biopsy After Radical Prostatectomy
Radical prostatectomy should reduce PSA to virtually undetectable
levels. Recurrent disease is suspected if the PSA starts rising. In
this situation, many urologists just arrange for radiotherapy of
the prostate bed and pelvis and do not rely on biopsy. If histologic
proof is needed before therapy, TRUS with biopsy can be used
to evaluate the anastomotic site and look for local lymphadenopathy
and pelvic masses (see Fig. 10.18E). If requested, in
such cases we obtain two samples from either side of the anastomosis
and perform biopsy of any other abnormal masses and
any SV remnants. mpMRI can help identify suspicious areas.
Care must be taken not to mistake large pelvic vessels for masses;
this can be avoided by using Doppler before biopsy (Fig. 10.20).
FIG. 10.20 Other Transrectal Ultrasound (TRUS) Applications:
Pelvic Mass. Woman with perirectal mass (arrow) shown to be recurrent
colon cancer by TRUS-guided biopsy. Note the large adjacent vessel.
When biopsy is performed outside the prostate, Doppler helps avoid
injury to vessels. The transrectal technique is useful for biopsy of any
pelvic mass in men or women that can be accessed by the probe.
Biopsy in Men With Absent Anus
Men who have had their anus closed by abdominoperineal
resection are diicult to manage when their PSA becomes elevated.
Prostate visibility is restricted through both the transabdominal
and the transperineal approach. Transperineal ultrasound–guided
biopsy with local anesthesia is moderately successful in obtaining
prostate tissue. It is helpful to precede the biopsy with mpMRI,
which may locate suspicious areas that cannot be seen with
ultrasound. Antibiotic prophylaxis and coagulation management
is the same as with TRUS biopsy. We scan the patient in the
decubitus position just as with regular transrectal biopsy, use
the same transrectal probe because of its small size, push it irmly
against the perineum, and proceed as with a transrectal biopsy
using local skin cleansing. Others scan using the lithotomy
position. A Foley catheter with inlated balloon and some luid
in the bladder can help to identify the prostate and to avoid
urethral injury. About 20 mL of 1% lidocaine is needed for
perineal anesthesia. Both lobes are systematically sampled and
extra cores are taken from suspicious regions. 167 Cancer yield is
about 30%; others report it as high as 40% to 82%. If ultrasound
visibility is very restricted owing to perineal distortion by surgery,
then an alternative approach using mpMRI for initial lesion
detection followed by CT transsciatic biopsy or in-bore MRIguided
biopsy could be considered.
OTHER APPLICATIONS OF
TRANSRECTAL ULTRASOUND AND
BIOPSY IN MEN AND WOMEN
In both men and women the transrectal route is useful to evaluate
and perform biopsy on any pelvic mass or structure that is within
range of the probe and needle. TRUS also provides high-resolution
pelvic access in girls and women when transvaginal ultrasound
is not possible (see Fig. 10.20).