Diagnostic ultrasound ( PDFDrive )

386 PART II Abdominal and Pelvic Sonography
diaphragm, which is the external urethral sphincter. In the
midplane the ejaculatory ducts (see Fig. 10.3A) are visible as
hypoechoic tracts extending from the VD at the base to the
centrally located verumontanum.
Parasagittally with hyperplasia, the anterior hyperplastic
transition zone can be seen separated from the posteriorly
situated peripheral zone by the surgical capsule. he VD
and SVs are visible above the base. Still more laterally, the
transition zone ends, leaving only the part of the peripheral
zone curving anteriorly at the sides of the gland (anterior
horns). 12
Histologically, the prostate does not have a true membranous
capsule but is surrounded by condensed connective tissue through
which the vessels and nerves course. On transverse and sagittal
imaging, the border appears sharply deined except at the
posterolateral margins where the neurovascular bundle enters
the prostate and makes the margin look ragged. his can hinder
determination of extracapsular extension by tumors 3,16 (see
Fig. 10.2C).
EQUIPMENT AND TECHNIQUE
Most modern ultrasound machines can be equipped with
transrectal probes and biopsy guides suitable for examination
of the prostate and rectum. It is advantageous to use the thinnest
probe to negotiate “tight” anal sphincters. End-ire probes
(Fig. 10.6) are suitable for most biopsy applications and allow
for multiplanar imaging in transverse and axial projections. hey
are well suited for biopsy guidance, allowing easy access to all
prostate regions including the apex and anterior gland. he current
G
FIG. 10.4 cont’d (G) Benign peripheral zone hyperplastic nodule.
Transverse image shows prominent isoechoic posterior nodule that
bulges the capsule and has a well-deined hypoechoic rim (arrow). It
resembles BPH nodules, which are normally seen in the transition zone,
but it is located in the peripheral zone. At palpation these feel hard and
can be mistaken for cancer. Biopsy is needed for reassurance to conirm
their benign nature. P, Prostate; U, urethra.
FIG. 10.6 Typical End-Fire Ultrasound Probe for Transrectal and
Intracavitary Work. Active element is at tip of probe, and needle in
guide ires parallel to probe (end-ire). In clinical use the probe and guide
would be covered by protective sheaths.
U
s
NV
A
B
FIG. 10.5 Normal Doppler Ultrasound Anatomy in Patient With Moderate Benign Prostatic Hyperplasia (BPH). (A) Axial view with power
Doppler ultrasound shows the urethral vessels (U), some vessels along the surgical capsule (S), and the neurovascular bundle (NV) on one side.
This is an average degree of vascularity. Note the large vessels, mostly veins, outside the prostate. Care must be taken when biopsy is performed
outside the prostate to avoid injury to these vessels. (B) Color Doppler low imaging is more dificult to interpret owing to different colors related
to low direction.