imaging of penile tumors

1. IMAGING OF PENIS.

2. Anatomy and Physiology
• The penis is composed of three cylindrical bodies
• of endothelium-lined cavernous spaces: the paired
• dorsolateral corpora cavernosa, and the single, ventral,
and midline corpus spongiosum.
• The variable MR signal intensity of these structures is
dependent on the rate of blood flow within the
cavernous spaces that constitute the corporal bodies.
In general, the three corpora are of intermediate T1-
weighted and high T2- weighted signal intensity.
• The corpora cavernosa are isointense relative to one
another, as they are connected via fenestrations in
their septum and therefore have similar flow.

3. • The corpus spongiosum is a separate space and may
normally have
• flow and signal intensity characteristics different from
those of the cavernosa. The posterior portions of the
corpora cavernosa are known as the crura, which flare
laterally to attach to the ischiopubic rami. The corpus
spongiosum arises within the perineum from the bulbous
spongiosum and extends anteriorly to form the glan penis.
• On axial T2-weighted images, the deep arteries of the
corpora cavernosa are depicted as small, round areas of
hypointensity (due to faster flow)within the medial, dorsal
portions of the cavernosa. A layer of fibrous tissue, the
tunica albuginea, surrounds both the corpora cavernosa
and the corpus spongiosum, but the layer is thicker around
the cavernosa

4. • A second fibrous layer, the Buck fascia, surround
the corpora cavernosa and separates them from
the corpus spongiosum. Composed of mature
fibrous tissue, both the tunica albuginea and
Buck fascia are imaged as low T1-weighted and
lowT2-weighted signal-intensity bands that
surround the corporal bodies.
• External to the Buck fascia is a loose layer of
subcutaneous connective tissue, which appears
hyperintense relative to the fascia at T2 weighting
• The deep dorsal vein of the penis lies in the
midline within this layer

5. • The posterior urethra consists of the prostatic
and membranous portions. The latter traverses
the urogenital diaphragm.
• The anterior urethra, which begins at the
urogenital diaphragm, consists of the bulbous
and pendulous portions of the urethra, both of
which are surrounded by the corpus spongiosum.
• If not dilated or distended, the anterior urethra is
difficult to see at MR imaging.
• On heavily T2-weighted images, the collapsed
muscular walls of the urethra are revealed as a
band of relative hypointensity compared with the
bright cavernous spaces of the corpus
spongiosum.

8. Vascular Anatomy
• The arterial supply to the penis originates
from the right and left internal pudendal
arteries,which, in turn, arise from the anterior
division of the internal iliac arteries . Each
internal pudendal artery gives rise to the
perineal and common penile arteries.
• The branches of the common penile artery are
variable but classically consist of three: the
bulbourethral artery, the dorsal artery of the
penis, and the cavernosal artery.

9. • The bulbourethral artery supplies the penile bulb,
the bulbourethral (Cowper) glands, and the
posterior aspect of the corpus spongiosum.
• It gives rise to the urethral artery, which parallels
the course of the urethra within the corpus
spongiosum.
• The paired deep dorsal arteries lie external to the
tunica albuginea within the hypodermal
connective tissue and course lateral to the deep
dorsal vein. They supply the penile skin and the
glans penis.

10. • The cavernosal arteries are easily visible on axial
MR images of the penis within the dorsal, medial
third of the corpora cavernosa.
• They give rise to multiple helicine arteries, which
supply the sinusoids of the corpora cavernosa.
• After the administration of gadopentetate
dimeglumine, enhancement of the cavernosa
proceeds centrifugally, extending from the region
surrounding the cavernosal arteries to the
periphery of the corporal bodies and from the
proximal part of the cavernosa to the distal

11. • The cavernosa are drained through the
emissary veins of the wall of the corpora.
Distally these veins drain into the unpaired
deep dorsal vein of the penis. Proximally, they
drain into the cavernous veins, which join with
the bulbar vein to form the internal pudendal
veins.

12. MRI OF PENIS
• MR imaging of the penis is facilitated by
appropriate positioning of the patient. With the
patient supine, a folded towel is placed between
the patient’s legs inferior to the perineum, to
elevate the scrotum and penis.
• The penis is then dorsiflexed against the lower
abdomen in the midline and taped in position to
reduce motion of the organ during the
examination .
• A 3-inch or 5-inch surface coil is employed to
maximize signal- to-noise ratio at small fields of
view

13. • If imaging of the penis in the erect state is required,
• prostaglandin E1 (alprostadil, 10 g) is injected into one of
the corpora. After injection, the patient is asked to massage
the injection site and to manually stimulate the penis until
it is erect.
• Intra-cavernosal injection of prostaglandinE1 is
contraindicated in men who have conditions that
predispose them to priapism, such as sickle cell anemia,
sickle cell trait, multiple myeloma, leukemia, cavernosal
thrombosis, and tumors that are known to invade the
cavernosa. Use of prostaglandinE1 is also contraindicated in
men with penile prostheses.
• Imaging protocols are customized to address the clinical
question. In general, though, we acquire axial (short-axis)
spin-echo T1-weighted and axial, sagittal, and fat-saturated
coronal fast spin-echo T2-weighted images.

14. • If gadolinium is administered, we employ either
• a two- or three-dimensional fat-saturated T1-weighted
gradient-echo pulse sequence before, during, and after
the dynamic administration of intravenous gadolinium
chelate. If the entire pelvis also needs evaluation, such
as in the case of penile malignancy, we obtain body coil
axial T1-weighted spin-echo pelvic images to look for
inguinal or obturator lymphadenopathy.
• Inpatients who undergo evaluation for arteriogenic
impotence, pelvic MR angiography is performed with a
three-dimensional T1-weighted gradient echo pulse
sequence and an approximately 36-cmfield of view to
obtain images from the distal aorta to the distal
pudendal arteries.

15. Penile Malignancies
• Squamous Cell Carcinoma of the Penis:-
• Most primary penile malignancies are squamous cell
carcinomas.
• most often during the 6th and 7th decades of life.
• most commonly diagnosed malignancies of men in Asia and
Africa.
• Uncircumcised men are more often affected, probably
because of the chronic irritative effect of smegma.
• At MR imaging, squamous cell carcinomas are
• usually hypointense relative to the corpora on both T1- and
T2-weighted images.
• At contrast enhanced imaging, these lesions do increase in
signal intensity but less so than the normal corporal bodies

16. • MR imaging may
• be performed for staging purposes. In the commonly
• used Jackson staging system,
• stage I lesions are confined to the glans or prepuce,
• stage II lesions involve the penile shaft,
• stage III extend to inguinal nodes,
• stage IV involve deep pelvic nodes or distant
metastases. Both computed tomography (CT) and MR
imaging depict pelvic lymphadenopathy, but MR
imaging is superior for evaluation of the primary lesion.

17. Imaging of Lymph Nodes
• Approximately 30%–60% of patients with
squamous cell carcinoma have palpable inguinal
lymph nodes at the time of initial diagnosis .
• In about one-half of these patients, the enlarged
nodes harbor metastatic disease; in the other
one-half, the palpable lymph nodes are reactive.
• The capacity of CT and MR imaging to help
detect lymph node metastases is limited because
the diagnosis is based on lymph node size. As a
result, occult metastases in normal-sized lymph
nodes will go undetected, whereas enlarged
nodes secondary to infection or inflammation will
be labeled as malignant.

18. • The recently introduced technique of lymphotrophic
nanoparticle–enhanced MR imaging allows the
characterization of lymph nodes in patients
• with various cancers. MR imaging is performed with
ferumoxtran-10, which consists of ultra small super
paramagnetic iron oxide particles.
• Normal lymph nodes contain macrophages, which
engulf the iron oxide nanoparticles. Malignant lymph
nodes lack the phagocytic cells needed to take up the
nanoparticles.
• Therefore, non metastatic lymph nodes show
homogeneous uptake of ferumoxtran-10 and appear
dark due to shortening of T2 and T2*, whereas
malignant lymph nodes do not take up the contrast
and appear bright

19. • Imaging of Distant Metastases.—Distant
metastasis
• is uncommon in patients who present with
penile cancer (3% of cases) . Generally, distant
metastases occur late in the course of the
disease and are associated with a dismal
prognosis. The most common sites of
metastases are the lung, liver, and
retroperitoneum.

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22. • Anterior Urethral Carcinoma:-Carcinomas of the male
urethra occur most often in the bulbous and
membranous portions of the urethra, followed by the
fossa navicularis.
• The anatomy of the urothelium changes along the
course of the male urethra, with
• 1]transitional cells lining the prostatic and
membranous segments,
• 2]stratified and pseudo stratified columnar epithelium
• in the bulbous and pendulous parts, and
• 3]squamous cells in the fossa navicularis and urethral
• meatus.

23. • Squamous cell carcinomas,
• Followed by transitional cell carcinomas and
adenocarcinomas, are the most common
anterior urethral Carcinomas.
• At MR imaging, urethral carcinomas are
usually hypointense relative to the normal
cavernosa on both T1- and T2-weighted
images

25. • Penile Sarcoma:-
• Primary sarcomas can also occur in the penis.
• These include epithelioid sarcoma, Kaposi sarcoma,
leiomyosarcoma, and rhabdomyosarcoma. All these
lesions are rare and together represent less than 5% of
all penile malignancies.
• Epithelioid sarcoma isointense relative to the corpora
on T1- weighted images, was hypointense relative to
the corpora on T2-weighted images, and enhanced less
than the normal corpora after administration of
contrast material.

26. • Leiomyosarcomas of the penis may arise from
either the smooth muscle of the glans or the
corpora cavernosa . Those that arise in the latter
tend to metastasize early because of their
proximity to the vascular structures of the penis.
• Rhabdomyosarcoma is the most common
malignancy of the lower genitourinary tract in the
first 2 decades of life. At MR imaging,
rhabdomyosarcoma generally is isointense
relative to skeletal muscle on T1-weighted
images, is hyperintense relative to muscle on T2-
weighted images, and enhances heterogeneously
after administration of contrast material.

28. • Metastases to the Penis
• Metastases to the penis are rare and may
manifest with malignant priapism .
• In approximately 70% of cases, penile metastases
arise from other primary malignancies of portions
of the genitourinary tract such as the prostate or
urinary bladder . Metastases from the colon,
stomach, esophagus, and pancreas have been
reported less often Metastatic spread of
malignancy to the penis represents an advanced
stage of disease, and prognosis is generally poor.

30. • Benign Masses:-
• MR imaging can be used to evaluate a number of
benign entities that manifest as palpable penile
masses, the nature of which may not be apparent at
clinical evaluation.
• Cowper Duct Syringocele
• Cowper duct syringocele represents cystic dilatation of
the main duct of the bulbourethral (Cowper) glands.
• At MR imaging, Cowper duct syringocele appears as a
midline oval structure at the penile base adjacent to
the ventral aspect of the proximal bulbous urethra and
is of high T2 signal intensity.

32. • Periurethral Abscess
• Uncomplicated cases of lower genitourinary
tract infection or inflammation do not require
imaging. Cases in which abscess is suspected
may benefit from imaging evaluation, and the
inherently high soft-tissue contrast afforded
by MR imaging makes it an excellent modality
for this purpose MR imaging can show the
relationship of the inflammatory mass to the
corporal bodies and urethra.

34. • Partial Cavernosal Thrombosis:- At MR
imaging, the affected cavernosal segment is
distended with thrombotic blood and may
compress the contralateral corpus
cavernosum. The signal intensity of the
affected segment is dependent on the age of
the thrombus. Generally, it is hyperintense
relative to the normal cavernosum on T1-
weighted images and hypointense on T2-
weighted images.

36. Peyronie’s disease
• Peyronie’s disease accounts for 0.3-0.7% of all urologic
disorders.
• It occurs most often in the fourth to sixth decades of
life, and occasionally in men less than 20 years old .
• Patients usually have increasingly painful erection and
deviation of the penis.
• The main clinical findings are hard, well-demarcated
plaques in the region of the tunica albuginea enclosing
the corpora cavernosa and of the septum penis.The
cause of the disease is still not fully explained, although
some evidence suggests that repeated microtrauma,
hormonal dysfunction, metabolic disorders (diabetes,
gout), and a general fibroplastic disposition may play a
role in the pathogenesis.

37. • Peyronie Disease
• Chronic inflammation that leads to fibrosis and focal
thickening of the tunica albuginea is termed Peyronie
disease.
• The indurated area, which maybe painful, results in varying
degrees of penile deformity with erection.
• If severe, this deformity may interfere with sexual
intercourse. Peyronie plaques may or may not calcify. If
calcified, the plaque may be visible at radiography, CT, and
US.
• At MR imaging, Peyronie disease is seen as focal thickening
of the tunica albuginea and is best seen on T2-weighted
images. After intravenous administration of gadolinium,
enhancement of the plaque has been shown to correlate
with the presence of active inflammation.