prostate gland, chestnut-shaped reproductive organ located directly
beneath the bladder in the male, which adds secretions to the sperm
during the ejaculation of semen. The gland surrounds the urethra, the duct
that serves for the passage of both urine and semen; rounded at the top,
the gland narrows to form a blunt point at the bottom, or apex. The
diameter in the broadest area is about 4 cm (1.6 inches). The two
ejaculatory ducts, which carry sperm and the fluid secreted by the seminal
vesicles, converge and narrow in the centre of the prostate and unite with
the urethra; the urethra then continues to the lower segment of the
prostate and exits near the apex.
The prostate gland is a conglomerate of 30 to 50 tubular or saclike glands
that secrete fluids into the urethra and ejaculatory ducts. The secretory
ducts and glands are lined with a moist, folded mucous membrane. The
folds permit the tissue to expand while storing fluids. Beneath this layer is
connective tissue composed of a thick network of elastic fibers and blood
vessels. The tissue that surrounds the secretory ducts and glands is known
as interstitial tissue; this contains muscle, elastic fibers, and collagen fibers
that give the prostate gland support and firmness. The capsule enclosing
the prostate is also of interstitial tissue.
In man, the prostate contributes 15–30 percent of the seminal
plasma (or semen) secreted by the male. The fluid from the
prostate is clear and slightly acidic. It is composed of several
protein-splitting enzymes; fibrolysin, an enzyme that reduces
blood and tissue fibers; citric acid and acid phosphatase, which
help to increase the acidity; and other constituents, including
ions and compounds of sodium, zinc, calcium, and potassium.
Normally the prostate reaches its mature size at puberty,
between the ages of 10 and 14. Around the age of 50, the size of
the prostate and the amount of its secretions commonly
decrease. Increase in size after midlife, often making urination
difficult, may occur as a result of inflammation or malignancy.
Males who do not secrete adequate amounts of the male
hormone androgen may maintain normal function of the
prostate with injections of androgen.
Zones of Prostate:
Central zone (CZ)
Cone shaped region that surround the ejaculatory ducts (extends from bladder
base to the veru) Likely stems from Wolffian ducts
25% of glandular tissue in young adults
Only 1-5% of prostate cancer from this region (likely because of Wolffian duct
Peripheral zone (PZ)
Mesodermal in origin
Majority of prostatic glandular tissue
Origin of up to 70% of prostate adenocarcinoma
Transitional zone (TZ)
Surrounds the prostatic urethra proximal to the veru (aka preprostatic urethra)
Endodermal in origin
In young men, accounts for only 5-10% of prostatic glandular tissue.
Only ~20% of prostate cancer arise from TZ
Gives rise to BPH
"Lobes" of the prostate
Enlargement of periuthral tissue in the TZ results in hyperplasia of "lateral lobes“
In some men, hyperplasia of periurethral glands of the TZ at the bladder neck
produces a "median lobe" -- tissue mass that can ball-valve into the outlet .
Imaging in Prostate Carcinoma:
Plain radiographs of the pelvis cannot be used to demonstrate localized
disease in the prostate, and they are generally only needed in the evaluation
of metastatic disease. Most skeletal metastases from prostate cancer (about
85%) are osteoblastic and are visible as an area of abnormal tracer activity
on a radionuclide bone scan. In case of doubt, targeted imaging with skeletal
radiographs can help distinguish metastatic areas from degenerative disease.
CT scanning has little value in demonstrating intraprostatic pathology
and in local staging. However, it may be helpful in detecting metastatic
disease, such as lymph node involvement or bone metastases.
Nodal staging is indicated in patients with a prostate-specific antigen
(PSA) value of 20 ng/mL or higher, a clinical stage T2b or higher, and a
Gleason score of 7 or higher. CT or MRI scans depict lymph node
enlargement and have similar accuracy for the evaluation of lymph node
metastases. However, nodal staging relies on assessment of lymph node
size, and neither CT scan nor MRI can demonstrate cancer within lymph
nodes that are not enlarged.
Morphologic MRI (T1- and T2-weighted imaging)
On T1-weighted images, the prostate appears homogeneous with medium signal
intensity; neither the zonal anatomy nor intraprostatic pathology is displayed, but if
the MRI is performed after biopsy, post biopsy hemorrhage can be identified as areas
of high T1-signal intensity. T2-weighted sequences exquisitely depict the prostatic
zonal anatomy. The central gland usually consists of nodular areas of varying signal
intensity, depending on the relative amount of hypointense stromal and hyperintense
glandular elements. The normal peripheral zone has high signal intensity (as it is
mainly composed of numerous ductal and acinar elements with hyperintense
secretions). Most prostate cancers can be visualized as low-signal-intensity areas
within the high-signal-intensity normal tissue background of the peripheral zone.
Because about 70% of all prostate cancers occur within the peripheral zone,
morphologic T2-weighed imaging can thus depict the majority of all prostate cancers.
On the other hand, low-signal-intensity tumors in the central gland are usually
indistinguishable from far more common hypointense stromal hyperplasia. Therefore,
central gland tumors are more difficult to detect than peripheral zone cancers. T2-
weighted imaging can be performed on a 1.5-Tesla unit, preferably with use of an
endorectal coil, or on a 3-Tesla unit. Reported sensitivities (22-85%) and specificities
(50-99%) vary widely, the latter illustrating the fact that low-signal-intensity areas are
by no means specific for prostate cancer, since benign conditions such as prostatitis,
hemorrhage, hyperplastic nodules, or post-treatment (hormonal or irradiation)
changes may equally show low signal intensity.
SPECTROSCOPY – NORMAL
• 3D proton MR spectroscopic metabolic mapping of the
entire gland is possible with a resolution of 0.24 ml per
• Proton MR spectroscopy displays concentrations of
citrate, creatine, and choline metabolites found in the
prostate gland and cancer.
• Normal prostate tissue contains high levels of citrate -
higher in the PZ than in the central gland.
• Prostatic cancer: higher cell membrane turnover,
Higher levels of choline and increased citrate.
Diffusion-weighted Imaging (DWI).
• Diffusion is the process of thermally induced random
molecular displacement – Brownian motion
• Diffusion properties of tissues are related
– Amount of tissue water
– Tissue permeability
• Cancer tends to have restricted diffusion due to
– High cell densities
– Abundant intracellular membranes
TRUS is widely available, well tolerated by patients, and relatively inexpensive. It
is optimally performed with high-frequency TRUS probes and the whole prostate is
imaged in the transverse and sagittal plane. The prostate volume can be
approximated by multiplying the height, depth, and width of the prostate with
0.52 (prolate ellipsoid formula).
With TRUS, the prostate is shown to be divided into an isoechoic peripheral zone
and a more heterogeneous central gland, comprising the transition zone.
Calcifications (corpora amylacea) are common at the boundary between the
peripheral zone and the central gland. The seminal vesicles can be visualized as
convoluted hypoechoic cystic structures
Radionuclide bone scanning after the injection of a technetium-99m
(99m Tc) tracer is the current standard for assessing potential bone metastases
from prostate cancer in patients with a prostate-specific antigen (PSA) value
above 20 ng/mL, a Gleason sum of 4+3 or higher, or in case of symptoms that
might be attributable to potential bone metastasis.Bone scans have a high
sensitivity but low specificity for metastatic prostate cancer. In case of doubt
(eg, degenerative vs metastatic disease), targeted imaging with plain films, CT
scanning, or MRI may be necessary. With diffuse bone metastases, a "superscan"
may be seen; this superscan demonstrates high uptake throughout the skeleton,
with poor or absent renal excretion of the tracer.
Congenital prostatic abnormalities are not commonly
encountered in clinical practice but can provide insight
into normal prostatic development. Furthermore,
understanding normal prostate embryology and molecular
signaling may provide novel approaches to the treatment
of prostatic neoplasia. This review examines normal fetal
development and congenital pathology of the prostate,
including 5-α-reductase deficiency, prostatic ectopia, the
prostate in the female pseudohermaphrodite, the prostate
in prune belly syndrome, prostatic utricle, and trisomy
Congenital prostatic abnormalities:
Axial and sagittal images of the prostate showing extensive hypoechoic areas. This
patient had a prostate-specific antigen level of 17 ng/mL and digital rectal examination
findings highly suggestive of cancer. Biopsy revealed granulomatous prostatitis.
Prostatic abscess - Axial T2W image (A) of the prostate shows a focus of
hyperintense signal (arrow) in the left midzone of the peripheral gland. On the axial
T1W image (B), the lesion is barely seen. An axial, contrast-enhanced, T1W image
(C) shows that the lesion (arrow) has peripheral enhancement and central non
enhancement. DWI (b value=800) (D) shows high signal in the lesion (arrow) due to
restriction of diffusion. The corresponding ADC map (E) shows low signal (arrow)
Prostatic abscess - Axial T2W MRI of the prostate (A) shows high signal (arrow) in the
central gland, in the left midzone. Axial T1W image (B) shows mixed signal intensity with
peripheral hyperintensity (arrow). Axial, contrast-enhanced T1W image (C) shows a
peripherally enhancing abscess (arrow). DWI (b=800) (D) shows restriction of diffusion
(arrow) in the lesion. The corresponding ADC map (E) shows low signal (arrow).
RISK OF PROSTATE CANCER BY AGE*
• < 39 years 1 in 10,100
• 40-59 years 1 in 38
• 60-79 years 1 in 14
• Lifetime 1 in 6
*American Cancer Society 2006
T STAGE (EXTENT OF THE TUMOR).
• TX: Primary tumor cannot be assessed
• T0: No evidence of primary tumor
• T1: Clinically unapparent tumor not palpable nor visible by imaging
– T1a: Tumor incidental histologic finding in 5% or less of tissue resected
– T1b: Tumor incidental histologic finding in more than 5% of tissue resected
– T1c: Tumor identified by needle biopsy (e.g., because of elevated PSA)
• T2: Tumor confined within prostate*
– T2a: Tumor involves 50% or less of one lobe
– T2b: Tumor involves more than 50% of one lobe but not both lobes
– T2c: Tumor involves both lobes
• T3: Tumor extends through the prostate capsule**
– T3a: Extra capsular extension (unilateral or bilateral)
– T3b: Tumor invades seminal vesicle(s)
• T4: Tumor is fixed or invades adjacent structures other than seminal
vesicles: bladder neck, external sphincter, rectum, levator muscles, and/or
Transrectal ultrasonographic imaging of prostate carcinoma (prostate-specific
antigen level = 1.8 ng/mL). Biopsy showed a Gleason score of 3 + 3. (A)
Transverse image reveals a slightly more echogenic peripheral zone (pz) and the
carcinoma nodule (n) as a more hypoechoic focus. cg = central gland. (B)
Sagittal image reveals a hypoechoic nodule (arrow). sv = seminal vesicle.
Sagittal image of the prostate showing a
hypoechoic area (white arrow). This area
was a focus of cancer on biopsy findings
Contrast-enhanced ultrasound showing
an enhancing prostate cancer.
Grayscale ultrasound showing a hypoechoic nodule in the left peripheral zone (arrow).
There is interruption of the normal green band on elastography with a stiff area that
corresponds to the nodule. Biopsy confirmed Gleason grade 7 prostate cancer.
T2 stage prostate cancer 2D T2W axial image on the left. 3D T2W axial image
on the right. Arrows depict a focal area of low signal intensity within the
normal high signal intensity peripheral zone consistent with T2 stage cancer.
T2 stage prostate cancer 2D T2W images on the left. 3D T2W images on the right. Coronal
images upper row. Sagittal images lower row. Arrows depict a focal area of low signal intensity
within the normal high signal intensity peripheral zone consistent with T2 stage cancer.
T3a stage prostate cancer. upper image: 2D T2W axial image lower image:
3D T2W axial image Arrows depict extracapsular extension of a focus of
low signal intensity on the left consistent with T3a prostate cancer
T3b prostate cancer Upper image: 2D T2W axial image Lower image:
3D T2W axial image Arrows depict focus of low signal intensity
within the seminal vesicles consistent with T3b prostate cancer.
Imaging of the prostate with and without endorectal coil. (A) Transverse image of
the prostate performed with phased-array coils without an endorectal coil reveals
adequate differentiation of the central gland (cg), peripheral zone (pz), and the
tumor nodule (n). However, visualization of the prostatic capsule near the tumor
is poor (arrow). (B) Transverse image of the prostate with the endorectal coil
shows the central gland (cg), peripheral zone (pz), and tumor nodule (n), with
better visualization of the prostatic capsule near the tumor (arrow).
Typical appearance of prostate carcinoma on magnetic resonance imaging. Subsequent biopsy
revealed a Gleason score of 4 + 4. (A) T1- weighted image shows homogeneous low signal of
the prostate (p), with no discrimination of the central and peripheral gland. The tumor nodule
is not seen because no tissue contrast is present between the tumor and peripheral zone. The
neurovascular bundles (black arrows) are seen laterally. (B) T2-weighted image shows the
lower-signal intensity tumor (n) compared to the curve from zone on either side. (C) Coronal
image shows the tumor nodule (n) with the adjoining apical prostatic capsule shown (arrow).
(D) Early-phase gadolinium chelate-enhanced sections from a fast 3-dimensional gradient
echo sequence show rapid intense enhancement of the tumor nodule (n), manifested by
brighter signal intensity in the rest of the prostate, with tumor extending laterally to greater
extent than is apparent on the T2-weighted image.
Prostatic carcinoma on magnetic resonance imaging with diffusion-weighted imaging of a
patient with a prostate-specific antigen level of 3.1 ng/mL. Subsequent biopsy revealed a
Gleason score of 3 + 4 with extracapsular extension. (A) T2-weighted and rectal coil image
reveals a tumor nodule (n) contrasted with a higher-signal intensity peripheral zone. The central
gland (cg) is expanded by benign prostatis hyperplasia, which has a lower signal intensity. (B)
Apparent diffusion coefficient (ADC) map of the prostate reveals that the tumor nodule (n) has a
lower signal intensity than the peripheral zone or the central gland (cg). Low signal intensity
indicates that the ADC is lower than that of water and the water diffusion within the tumor is
restricted. The ADC map is calculated from a set of three images at the same level (not shown)
and performed with three different magnitudes of strength of diffusion-encoding gradients. (C)
Early-phase gadolinium chelate-enhanced slice from a fast 3-dimensional gradientecho
sequence reveals rapid, intense enhancement of the tumor nodule (n). Portions of the central
gland (cg) also reveal rapid enhancement.
Typical enhancement characteristics of a tumor on dynamic contrast-enhanced images in a
patient with a prostate-specific antigen level of 15 ng/mL. Biopsy showed a Gleason score
of 4 + 4. (A) Transverse T2-weighted image reveals a tumor nodule (n) involving both the
central gland and the peripheral zone on the right side of the prostate. The arrow points
to the capsular involvement on the right. (B) Early-phase gadolinium chelate-enhanced
slice from a fast 3-dimensional gradient-echo sequence reveals a rapid, intense
enhancement of the tumor nodule (n) on the right side of the prostate. (C) Late-phase
enhanced T1-weighted image reveals the tumor nodule (n) with a lower signal intensity,
indicating washout of the contrast compared with the rest of the prostate. Typically, a
tumor demonstrates early enhancement and early washout (as shown in this case).
Axial T2 and DCE images show a 9 x 7 x 9 mm tumor abutting the capsule. A
distinct capsule can still be seen, suggesting capsular infiltration without ECE.
T2-weighted imaging (left) of a man with extensive Gleason 3+4 tumor
shows low signal thoughout the peripheral zone corresponding to tumor.
Very high b-valued high-resolution DWI (right) image shows restricted
diffusion in the same tumor compared to normal prostate.
Axial T2W–MRI, b | apparent diffusion coefficient map of diffusion-weighted MRI,
and c | raw DCE–MRI demonstrate a 1 cm right apical mid-peripheral zone lesion
(asterisk). d | Magnetic resonance spectroscopy shows an elevated choline.
Axial T2W–MRI, b | apparent diffusion coefficient map of DW–MRI, and c | raw
DCE–MRI demonstrate a large 5 cm lesion, which affects almost the entire
prostate (asterisk). d,e | The lesion has extra capsular extension.
Cancer prostate at the peripheral zone with high
Choline peak and a low Citrate peak are evident.
Peripheral prostate cancer in the right middle gland, producing a
capsular bulging (arrow) with high choline peak and low citrate.
Focal (A) and multifocal (B) distribution of prostate carcinoma within the prostate
gland (arrows). Scatter plots of the segmental 11C-choline maximal standardized
uptake value reveal higher 11C-choline maximal standardized uptake values in
most segments with prostate carcinoma compared with segments with benign
histopathological lesions. From Reske SN, Blumstein NM, Neumaier B, et al.
Imaging prostate cancer with 11C-choline PET/CT.
Gentleman with prostatectomy 10 years previously. External beam radiation 1 year previously
for a rising PSA. The PSA continued to increase up to 6.9 ng/mL. The 3 dimensional Carbon-11
Acetate PET/CT images show a small metabolic lymph node in the left pelvis (yellow arrows).
This would not have been diagnosed on CT alone based on its small size. Other areas of ‘red’
seen on the images are of normal Carbon Acetate in the intestines, kidneys, liver and spleen.
No other lesions were seen. The left pelvis node was treated with IMRT and the PSA then
decreased to 0.9 ng/mL, confirming involvement of the identified node.
Gentleman with Gleason 7 prostate cancer and external beam radiation (EBRT) to
the prostate 4 years previously. PSA nadir was 0.43ng/mL. Rising PSA to 3.9
ng/mL. The 3 dimensional Carbon-11 Acetate PET/CT images show a metabolic
focus in the right side of the prostate gland (yellow arrows). No other lesions
were seen. The prostate recurrence was confirmed by biopsy with subsequent
Brachytherapy performed. The PSA decreased to 0.6 ng/mL after treatment.
Gentleman with Gleason 6 prostate cancer. Brachytherapy and external beam radiotherapy
12 years previously. PSA nadir was 0.16 ng/mL. Rising PSA to 2.17 ng/mL. The 3
dimensional Carbon-11 Acetate PET/CT images show a single small metabolic lymph node
in the left upper pelvis (yellow arrows). As in Case example #1, this would not have been
diagnosed on CT alone based on its small size. Bilateral pelvic lymph node dissection was
performed with 13 nodes removed. The node identified on the C11-Acetate imaging study
was confirmed to be involve with prostate cancer (Gleason 4+4=8) and all other removed
nodes were negative/benign, confirming the solitary finding on the imaging study. The PSA
decreased to 0.19 ng/mL after the lymph node surgery.
Prostatic sarcoma is an uncommon and heterogenous
group of tumour arising from mesenchymal cells in and around the
In children the most common tumour type is a prostatic
rhabdomyosarcoma, which accounts for approximately a third of all
prostatic sarcomas .
In adults leiomyosarcomas are most common, accounting for
approximately a quarter of all cases . Many other sarcomas have
been reported although in general they are rare.
Overall prostatic sarcomas include:
rhabdomyosarcoma : most common in children
leiomyosarcoma : most common in adults
malignant fibrous histiocytoma
phyllodes tumour (also known as cystosarcoma phyllodes of the
undifferentiated stromal sarcoma