Nuclear imaging techniques play various roles in prostate cancer assessment and management. Conventional bone scintigraphy using technetium-99m is effective for detecting bone metastases, though it lacks specificity. PET tracers like FDG have limited utility in prostate cancer due to typically low glucose metabolism in prostate tumors. However, PET may help stage more aggressive primary tumors or locate recurrent disease when conventional imaging is negative. Newer tracers targeting prostate-specific membrane antigen (PSMA) show promise, with radioimmunoscintigraphy using Indium-111-capromab demonstrating reasonable sensitivity and specificity for detecting prostate cancer lesions.

1. Nuclear imaging in prostate
cancer
MIAD ALSULAMI

2. Objectives:
 To review the anatomy of prostate cancer.
 To Understand Gleason score and how it is performed .
 The role of tumor markers in prostate cancer assessment.
 The role of conventional imaging in the diagnosis of primary disease
 The role of SPECT tracers in prostate cancers.
 Does FDG PET-CT have a role in prostate cancer.
 PET tracers beyond FDG .

3. Introduction:
 Prostate cancer is the most common malignancy and the second most
common cause of cancer-related mortality in men.
 Although the treatment for localized prostate cancer is highly successful,
about 30–50 % of men will experience a biochemical failure within 10
years from the primary treatment, suggesting that prostate cancer can
metastasize relatively early in the course of disease .
 A portion of men with biochemical failure will develop locally recurrent
disease, and as many as two-thirds will have evidence of osseous
metastatic involvement .

4.  Once men developed metastatic disease, the median survival time to
death was 5 years .
 If men develop castrate resistant metastatic disease, the 1-year
survival is about 24 % with a median survival of only 8-18 months .

5. Applied Prostatic Anatomy:

6.  a healthy human male prostate is as slightly larger than a walnut.
 The mean weight of the normal prostate in adult males is about 11 grams,
usually ranging between 7 and 16 grams.
 A study stated that prostate volume among patients with negative
is related significantly with weight and height (Body Mass Index), so it
necessary to control for weight.
 Obesity and height were significantly associated with greater prostate
volume, particularly among men with a negative biopsy.
 Results suggest obesity management may be an effective method to
reduce prostate volume among men without high-grade prostatic
intraepithelial neoplasia or prostate cancer.

7. Santorini's plexus

8.  Santorini's plexus or prostatic plexus named after the Italian
anatomist Giovanni Domenico Santorini.
 The prostatic veins form a well-marked prostatic plexus which lies partly
in the fascial sheath of the prostate and partly between the sheath and
the prostatic capsule .
 It communicates with the pudendal and vesical plexus .
 The prostatic venous plexus drains into the internal iliac vein which
connects with the vertebral venous plexus, this is thought to be the
of bone metastasis of prostate cancer.

10. Diagnosis of prostate cancer:
 1- DRE :
- unpleasant procedure to the patient.
- Subjectively .
 2-Biochemical assay :
-67% false positive
-15% false negative
-can lead to unnecessary biopsies .
 3- TRUS and biopsy :
-complicated procedure.
- Has some side effects( infection and erectile dysfunction)

12. Gleason score :
 The Gleason grading system is used to help evaluate the prognosis of
men with prostate cancer using samples from a prostate biopsy.
 A Gleason score is given to prostate cancer based upon its microscopic
appearance.
 Cancers with a higher Gleason score are more aggressive and have a
worse prognosis.

13. Pattern 1 (rarely seen)
 The cancerous prostate closely resembles normal prostate tissue.
 the glands are small, well-formed, and closely packed. This corresponds
to a well differentiated carcinoma.

14. Pattern 2: ( rarely seen)
 The tissue still has well-formed glands, but they are larger and have
more tissue between them, implying that the stroma has increased.

15. Pattern 3: ( the most common pattern)
 The tissue still has recognizable glands, but the cells are darker.
 some of these cells have left the glands and are beginning to invade the
surrounding tissue or having an infiltrative pattern.
 This corresponds to a moderately differentiated carcinoma.

16. Pattern 4:
 The tissue has few recognizable glands.
 Many cells are invading the surrounding tissue in neoplastic clumps.
This corresponds to a poorly differentiated carcinoma.

17. Pattern 5:
 The tissue does not have any or only a few recognizable glands.
 There are often just sheets of cells throughout the surrounding tissue.
 This corresponds to an anaplastic carcinoma.

18. The grading system:
 after analyzing the tissue samples, the pathologist then assigns a grade to
the observed patterns of the tumor specimen.
 Primary grade - assigned to the dominant pattern of the tumor (has to
be greater than 50% of the total pattern seen).
 Secondary grade - assigned to the next-most frequent pattern (has to
be less than 50%, but at least 5%, of the pattern of the total cancer
observed).
 Tertiary grade - increasingly, pathologists provide details of the "tertiary"
component. This is where there is a small component of a third (generally
more aggressive) pattern.

19. Scores:
 The pathologist then sums the pattern-number of the primary and
secondary grades to obtain the final Gleason score.
 If only two patterns are seen, the first number of the score is that of the
tumor's primary grade while the second number is that of the secondary
grade.
 If three patterns are seen, the first number of the score would be the
primary grade and the second number the pattern with the highest
grade.
 This is a slight change from the pre-2005 Gleason system where the
second number was the secondary grade (the grade of the second-most
common cell line pattern)

20. Example
 if the primary tumor grade was 2 and the secondary tumor grade was 3
but some cells were found to be grade 4 ,What is the Gleason score?
the Gleason score would be :
2+4 (the pattern with the highest grade )=6.

21.  Gleason scores 2-4 are typically found in smaller tumors located in the
transitional zone (around the urethra). These are typically found
incidentally on surgery for benign prostatic hyperplasia.
 The majority of treatable/treated cancers are of Gleason scores 5 - 7 and
are detected due to biopsy after abnormal digital rectal exam or prostate
specific antigen evaluation.
 Tumors with Gleason scores 8-10 tend to be advanced neoplasms that
are unlikely to be cured.
 There is some evidence suggests that prostate cancers will become more
aggressive over time, Gleason scores usually remain stable for a few
years.

22. Tumor Markers for prostate cancer :
 A tumor marker in a biomedical setting can be defined as a biological object
present in human tissue and/or body fluids that is capable to differentiate
between normal and abnormal biological conditions.
 markers have a prognostic value to stratify patients in groups that have
different outcomes.
 Monitoring markers are measured before, during, and after treatment to
determine effectiveness of therapy.

23. PSA:
 Prostate-specific antigen (PSA) is a highly effective and established
monitoring marker for efficacy of radical prostatectomy, hormone
therapy, and/or radiotherapy.
 PSA, also known as KLK3 or hK3, is a member of the human kallikrein
family.
 PSA protein has a half-life of 2–3 days and is secreted by prostatic
epithelial cells into seminal fluid.
 PSA can be found in serum but with a concentration of about 106 times
less as compared to seminal fluid.

24.  In seminal fluids, it functions as a protease that liquefies semen .
 Although PSA is highly specific for prostate epithelial cells, in much smaller
concentration, it can be measured in malignant breast cells, salivary
gland, bowel, other urological tissues, and renal carcinoma cells.
 PSA is organ specific because after removal of all prostate tissue, PSA
values become immeasurable in serum.
 Although PSA is organ specific, some of the urological conditions such as
benign prostate hyperplasia (BPH), prostatitis, or mechanical damage
also contribute to aberrant PSA values in serum.

25.  the production of PSA by prostate cancer cells is not higher than benign
prostate epithelial cells, but higher serum values are a result of an
altered prostate-blood barrier
 Studies have shown that PSA production by prostate cancer cells is
generally lower.

26. PSMA:

27.  PSMA (prostate-specific membrane antigen), it is a type II
transmembrane glycoprotein.
 PSMA has an intracellular and extracellular domain Its function is limited
to hydrolyzing peptides in prostatic fluid and generating glutamate .
 This protein is expressed in a number of tissues such as prostate,
nervous system, and kidney

28.  it has been shown to have a higher expression in prostate cancer.
 This finding could possibly be related to its enzymatic activity and thus
invasiveness growth of prostate cancer .
 In the field of prostate cancer, PSMA has been the focus of many
research groups.
 It has mainly been suggested as a prognostic tool.

29.  studies have showed an increased expression in progressive prostate
cancer and hormone-independent prostate cancer .
 In serum from prostate cancer patients, the PSMA protein is increased,
with a higher expression in advanced stages of cancer.

30.  its function as a marker for prostate cancer is limited.
 The promising feature of PSMA is its application in tissue targeted
therapy such as prostate-specific cancer vaccine therapy or
radioimmunotherapy.

32. The role of conventional imaging in
prostate cancer .
 TRUS:
1. it is the most commonly used modality to detect prostate pathology .
2. TRUS has become a mainstay for imaging-guided prostate.
 Advantages:
1. ability to direct the biopsy needle precisely into regions of interest.

33. Limitations:
1. Highly operator dependent and thus is unsuitable as a screening test.
2. in experienced hands sensitivity and specificity to detect prostate
cancer is only has high as 50 %

34. Prostate cancer usually
hypoechoic but can be hyper
or isoechoic .

35. CT scan:
 Not accurate at detecting in situ prostate cancer.
 commonly obtained before the onset of radiation therapy to identify
bony landmarks for planning.
 In advanced disease, CT scan is the test of choice to detect enlarged
pelvic and retroperitoneal lymph nodes, hydronephrosis and
osteoblastic metastases .
 it still plays a relatively minor role in the staging of prostate cancer in
most large centers.
 CT can be used to locate and guide biopsy of solitary bone lesions to
confirm the presence of metastatic disease in patients who are otherwise
suitable for radical local therapy.

36. Limitations:
1. It has limited soft tissue resolution when compared to MRI, and its
inability to differentiate the prostatic capsule from the surrounding
structures limited its use in local staging.
2. Its role in staging patient with advanced disease is limited and
depends mainly upon the size of lymph nodes to determine if they are
involved.
3. Micro metastases can readily be missed, or benign enlarged nodes can
be incorrectly called as metastatic.

37. MRI:
 The primary indication for MRI of the prostate is in the evaluation of
prostate cancer after an ultrasound guided prostate biopsy has
confirmed cancer in order to determine if there is extracapsular
extension.

38. Signal characteristics:
 T1: useful for detection of prostate contour, neurovascular bundle
encasement, and post-biopsy hemorrhage .
 T2: on T2-weighted images prostate cancer usually appears as a region of
low signal within a normally high signal peripheral zone

40. Dynamic Contrast-Enhanced MRI
 Dynamic contrast-enhanced MRI (DCMRI) demonstrates the vascularity
and vascular permeability of tissues over time.
 Tumors tend to have permeable vessels that leak contrast after
injection and also demonstrate early rapid enhancement.
 not routinely used in staging prostate cancer.

41. MR spectroscopy:
 It is a new technique for displaying metabolic information .
 it relies on the differences in frequency for chemical shifts that exist
due to different chemical environments.
 It can be used to detect the absence or presence of certain compounds
and can assist in differential diagnosis when standard clinical imaging fails.
MRS can be used for tumor localization characterization planning, and
therapy evaluation .
 Three metabolites are measured, citrate, choline, and creatine.
 A reduced level of citrate and increased level of choline is suggestive of
prostatic cancer.

43. The role of nuclear medicine in
prostate cancer :
 The principle of nuclear medicine imaging and therapy involves the
administration of radioactive material which is attached to a pharmaceutical
designed to localize to the organ of interest, that is, the target organ.
 Both SPECT and PET modalities have a role in role in recurrent prostate
cancer .
 The resulting image is of lower resolution than other imaging modalities such
as computed tomography (CT) or magnetic resonance imaging (MRI) but has the
advantage of reflecting functional processes, that is, what is happening at a
cellular level.

44. The Role of SPECT in prostate
cancer:
 1-bone scintigraphy:
1. Metastatic spread of prostate cancer is most common to lymph nodes and bone, with bone
metastases evident in 90 % of patients dying from this condition .
2. uses of the radioisotope technetium-99m, labeled to a diphosphonate, the most commonly
used being 99m Tc-methylene diphosphonate ( 99m Tc-MDP), and is a quick, cost-effective
method of imaging the whole skeleton.
3. It is currently the primary test for the assessment of skeletal metastases in prostate cancer

45. Prostate cancer is usually
osteoblastic ! Why?

46.  The osteoblastic response is further stimulated by prostate specific antigen
(PSA) which has been shown to encourage osteoblastic proliferation
while at the same time causing apoptosis of the osteoclastic precursors .
 These factors give rise to the typical appearance of a sclerotic rather than
lytic lesion.

47. Limitations :
 false negatives can occur with slow-growing lesions and some aggressive
metastases that cause severe destruction of bone, leading to occult or
photopenic defects .
 specificity is limited as the tracer is not tumor specific and can accumulate
in a variety of conditions, such as Paget’s disease, degenerative change,
recent surgery, and infections leading to false positive results.
 Bone scintigraphy is commonly used in the initial assessment of high-
risk patients (PSA > 20 ng/ml, Gleason score > 8, bone pain or stage
T3/T4 disease and postoperative patients with a rising PSA level.

49. Radioimunoscintography:

50.  ProstaScint® (capromab pendetide) is the murine monoclonal antibody .
 This antibody is directed against Prostate Specific Membrane Antigen
(PSMA).
 Radio immune targeting using capromab pendetide (ProstaScint) labeled with
indium-111 is useful in the detection of prostate cancer cells showing
sensitivities and specificities of 60% and 70 % respectively
 due to its limited availability and cost, it is not currently used in the
preoperative assessment of patients.

51.  The overall sensitivity in several studies showing average sensitivities of
60%, specificities of 70%, positive predictive value of 60%, and negative
predictive value of 70%.

52. Limitations:
 It has a poor detection of soft-tissue lesions, including the primary lesion.
 when these earlier assays were used, 5% of men developed human anti-
mouse antibodies (HAMA).
 The presence of HAMA may falsely elevate levels of PSA

54. FDG PET-CT

55. The role of PET-CT in prostate cancer:
 FDG( does it have a role in prostate cancer ?)
1. The use of (FDG)in prostate cancer depends on the phase of the disease
.
2. Incidental high FDG uptake in the prostate gland,although rare,should
prompt further investigation with at least measurement of serum
prostate specific antigen level.
3. aggressive primary tumors with Gleason score7 tend to display high
FDG uptake .
4. PET with FDG may be useful in staging of those patients with aggressive
primary tumors and can localize the site of the diseases in patients with
biochemical failures and negative conventional imaging .

56.  normal prostate gland demonstrates low grade homogenous FDG uptake
.
 some studies attempt to quantify the SUV uptake in normal prostate
cancer 1.3-+0.4.
 focal FDG uptake with SUV max grater then 6 should be evaluated .
 some studies suggested that any focal FDG uptake should not be ignored
and at least PSA should be considered.

57. Limitations of FDG-PET CT:
 The challenge for detection of primary tumors may be related to the
heterogeneity of the lesion that can be intermixed with normal and
benign tissues, the small size of some tumors, the possible interference
from the high activity level in the nearby urinary bladder, and the
underlying biology of prostate cancer which in general may display low
rate of glycolysis and prefer other pathways such as fatty acid metabolism
for growth.

58. A man with biochemical failure (serum
PSA 22.5 ng/mL) after radical
prostatectomy.

59. PET Tracers Beyond FDG in Prostate
Cancer:
 there are many useful and emerging PET tracers beyond FDG, which
provide added value.
 choline, acetate, amino acids, bombesin,dihydrotestosterone and PMSA
labelled Compunds .
 11C- choline and 18F-choline are in wide clinical use outside the United
States, and they have proven most beneficial for detection of recurrent
prostate cancer.

60. Choline:
 is a substrate for the synthesis of phosphatidylcholine, which is the major
phospholipid in the cell membrane.
 The uptake of choline is mediated by a specific transporter, upregulated .
 The physiological uptake of 11C-choline includes salivary glands, liver,
kidney parenchyma, and pancreas, with faint uptake in spleen, bone
marrow, and muscles. Bowel and bladder activity can occasionally be
observed.
 11C has a half-life of 20 minutes, so it must be used rapidly after
production.

61.  To overcome the drawback of short half-life of 11C, an 18F-labeled choline
tracer (18F-fluorocholine or FCH) was developed as an alternative.
 The main difference between 11C-choline and 18F- choline is the earlier
urinary appearance of the 18F probably because of incomplete tubular
reabsorption. This aspect can affect the tracer performance for local
relapse detection.

62. patient after radical
prostatectomy and
adjuvant ADT. PSA
subsequently increased
to 2.3 ng/mL.

64. Role of choline in primary disease
 Early detection of prostate carcinoma is important because cancer
confined to the prostate gland is often curable.
 the ability to image localized prostate carcinoma remains limited.
 (MRI) is the best available imaging technique for identifying prostate
carcinoma .

65. Role of choline in assessing
recurrence :
 Monitoring PSA serum level is the best way to detect early disease
recurrence after primary treatment.
 Choline has a role in assessing recurrence but its role limited to PSA level
.

66. Does ADT have an effect on Choline
uptake ?
 Androgen deprivation therapy (ADT) is a systemic treatment that is often
used in relapsed patients as ADT influences tumor progression.
 there was general concern about its possible influence on 11C-choline-
PET-CT detection rate.

68.  Fuccio et al investigated this issue by means of sequential F18-choline-
PET-CT in 14 patients with recurrent prostate cancer during follow-up
after radical prostatectomy with rising PSA levels.
 All patients had undergone at least two consecutive F18-choline-PET-CT
scans before and 6 months after ADT administration.
 The mean serum PSA level before ADT was 17.0 –44.1 ng/mL.
 After 6 months of ADT administration, the PSA value significantly
decreased in comparison to baseline (PSA 2.4 -3.1 ng/mL.

69.  These preliminary results suggested that ADT significantly reduces -
choline uptake in patients with androgen-sensitive prostate cancer.

70. In summary:
 choline-PET-CT is neither indicated for primary prostate cancer detection
nor for routine staging.
 it has played an important role in the detection of locoregional LN and
distant recurrence in patients with biochemical recurrence, significantly
influencing patient management.

71.  In patients with low PSA or slow PSA kinetics or with both, the sensitivity
of choline-PET-CT is limited.
 11C-choline has been approved by the U.S. Food and Drug
Administration for imaging of patients with suspected prostate cancer
recurrence .

72. Acetate :
 Acetate is a naturally occurring fatty acid precursor that is converted to
acetyl-CoA, a substrate for the tricarboxylic acid cycle.
 Acetyl-CoA is incorporated into cholesterol and fatty acids .
 Most intense activity is present in pancreas, salivary glands, liver, spleen,
and variably in bowel.
 No urinary excretion of tracer is measurable.

73.  the major elimination route of 11C-acetate is through the respiratory
system as c11-co2 .
 lack of significant renal activity at imaging improves the detection of small
retroperitoneal nodes.
 Doesn’t have a role in assessing primary disease (low specificity) and thus
MRI is preferable.
 limited role in staging .
 it has a good performances in patients presenting with bio-chemical
relapse, even with low PSA values.

74. 11C-acetate-PET in a patient 5 months after radical
prostatectomy with a PSA of 1.64 ng/mL.

75. 11C-acetate-PET in a patient after intensity modulated radiation
therapy with rising PSA of 25.4 ng/mL.

76. Amino Acid PET tracers:
 amino acid transport and metabolism is upregulated in prostate and
other cancers such as brain tumors.
 Many amino acid transporter systems are overexpressed in prostate
cancer, particularly the system ASC transporter ASCT2 and the system L
transporter LAT1, which have been associated with tumor aggressiveness
and poor survival.
 Both natural and synthetic radiolabeled amino acids have been used for
prostate cancer imaging, and tumor visualization .

77.  naturally occurring amino acids such as methionine and tryptophan-
[11C]methionine (MET) was initially compared with FDG for PET imaging in
patients with progressive prostate cancer
 Results have shown higher uptake and sensitivity by MET compared with
FDG for bone and soft tissue lesions.
 [11C]methionine Has some limitations which is false results due to BPH
and chronic prostatitis.

78. Synthetic amino acids:
 One of the fluorinated synthetic amino acid PET radiotracer that has been
subject to the most extensive investigation for prostate cancer is anti-
1-amino-3–18F-fluorocyclobutane-1-carboxylic acid (FACBC or
fluciclovine)

79.  the current status of fluciclovine, still under trials in the US and the UK.
 the U.S. Food and Drug Administration (FDA) recently approved
fluciclovine, under the trade name Axumin.

80. Bombesin:
 Amino acid that targeted gastrin-releasing peptide receptor (GRPR) that
is reported to be overexpressed in prostate cancer with little to no activity
in normal or hypertrophied prostate tissue.
 GRPR overexpression has been reported in 63%-100% of primary
prostate cancer lesions and in 50%-85% of nodal and skeletal metastasis .
 Both receptor agonist and antagonist ligands have been labeled with a
variety of radionuclides including 18F, 64Cu, and 68Ga.

81. 18F-Fluorodihydrotestosterone:
 Androgens play an important role in the pathogenesis of prostate cancer,
and overexpression of androgen receptors (ARs) occurs in all stages of
the disease.
 A PET radiotracer based on dihydrotesterone, 16β-18F-fluoro-5α-
dihydrotestosterone (FDHT), which binds to sex hormone–binding
globulin and passively diffuses into the cytoplasm where it binds to the
AR.
 Larson et al117 studied uptake in seven patients with progressive
metastatic prostate cancer compared with FDG.
 FDHT was positive in 46 of 59 lesions, whereas FDG was positive in 57 of
59 lesions.
 The usefulness of DHT imaging is still uncertain.

82. 18F-NaF-PET/CT:
 18F-NaF is a positron emitter, which was used for bone imaging more
than 40 years ago for the first time.
 18F-NaF is produced by cyclotron with a half-life of approximately 110
minutes.
 The mechanism of uptake is quite similar for 99mTc-MDP and 18F-NaF by
chemisorption of 18F-NaF to hydroxyapatite, it converts to
fluoroapatite and a hydroxyl group [Ca5(PO4)3OH þ F - Ca5(PO4)3F þ OH ].

83.  18F-NaF has almost 100% first-pass clearance.
 Its uptake in the bone is correlated to the bone remodeling, activity of
osteoblasts, and to blood flow.
 18F-NaF-PET/CT has some advantages such as less plasma protein
binding with resultant higher bone uptake and faster serum clearance as
well as shorter uptake time (30-45 minutes instead of 2-3 hours), greater
spatial resolution and better image quality with higher target-to-
background ratio.
 It can also detect both lytic and blastic osseous metastases.

84. Limitations:
 Though it has excellent sensitivity 93% the specificity is poor around
54%.
 low specificity might be due to many false-positive lesions, most likely
attributable to benign degenerative or inflammatory lesions in these
often elderly patients.
 Another limitation of 18F-NaF-PET/CT is lack of uptake in small metastatic
lesions that are not able to trigger an osteoblastic reaction, specifically in
the spine.

85. Patient with prostate cancer with known bone metastases with increasing PSA level
of 153 ng/mL after chemotherapy.

86. Prostate Specific Membrane Antigen (PSMA)-Targeted Agents:
 Prostate specific membrane antigen (PSMA) is overexpressed on prostate
cancers, especially those with more aggressive histologic features.
 The first generation of PSMA-targeted molecules was antibodies. 111In-
capromab pendetide was FDA approved in the 1990s .
 In the early 2000s, small molecule PSMA antagonists began to be
developed.
 68Ga-PSMA-HBED-CC PSMA developed in Europe.

87. 68Ga-PSMA :
 Several studies promise accurate staging of primary prostate cancer and
restaging after biochemical recurrence with 68Ga-PSMA ligand Positron
emission tomography/computed tomography (PET/CT).

88.  68Ga-PSMA ligand PET/CT has higher diagnostic accuracy compared to
conventional imaging including PET with other tracers (e.g. 18F-Choline,
11C-Choline).
 68Ga-PSMA ligand PET/CT showed accurate staging of primary PC and
restaging after biochemical recurrence.

89.  Ga-PSMA ligand PET imaging has been shown to increase detection of
metastatic sites even at low PSA-values in comparison to conventional
imaging or PET examination with different tracers.
 some studies indicate that the detection rate of bone metastasis with
68Ga-PSMA ligand PET/CT is clearly superior to traditional bone scan.
 It’s recently reported about an increased 68Ga-PSMA ligand uptake in a
patient with Paget’s disease probably related to an overexpression of
PSMA in areas with an abnormal bone remodeling and increased
vascularity.

90. Normal distrbiuation

91.  in PET any focal uptake of 68Ga-PSMA ligand higher than the surrounding
background and not associated with physiological uptake has to be
considered suspicious for malignancy and judged and described below.
 68Ga-PSMA ligands are not completely specific for PC .
 several case reports exist showing increased PSMA uptake in benign
lesions such as thyroid adenoma, Paget’s disease, schwannoma,
tuberculosis, adrenal adenoma or splenic sarcoidosis

92.  other malignant lesions presenting with increased PSMA expression have
been reported for glioblastoma, hepatocellular carcinoma, lung cancer,
renal cell carcinoma and thyroid cancer .
 primary lung cancer lesions can also show high PSMA-expression by
68Ga-PSMA ligand PET .

93. LIMITATIONS:
 Can be taken up by other malignant and benign lesions .
 68Ga is produced in a generator that must be purchased annually and
then the agent is synthesized locally.
 The 68 min half-life of 68Ga makes it difficult to ship from a central
source.

94. 68Ga-PSMA ligand PET/CT in a 78-year old patient with
primary PC (Gleason score 7, iPSA 34.3 ng/ml).

95. Example of a 68Ga-PSMA ligand PET/CT examination with
incidental finding of a moderate, focal PSMA-ligand uptake in a
left-sided coeliac ganglion .

96. 18F DCFBC:
 an alternative 18F-based compound, 18F DCFBC, has been developed.
 Preliminary experience with this tracer is promising.
 In localized disease, there is no uptake in benign prostatic hyperplasia,
however it has limited role in assessing primary disease
 Rowe etal studied 13 patients scheduled for prostatectomy who were
imaged with 18F DCFBC.
 Dedicated prostate MR was also obtained in 13 patients and proved to be
more sensitive in primary cancer detection than 18F DCFBC.

97. 18F DCFPyL :
 It is a second generation of 18F agent.
 Dietlein et al compared 18F DCFPyL to 68Ga PSMA in 14 prostate cancer
patients with biochemical relapse and noted some diffreances in
detecting lesions.
 18F DCFPyL demonstrated higher SUVs and actually localized more
lesions in three patients.

98. Which one the best?
it is too early to answer the question

99. In conclusion:
 the PSMA-based agents appear to have excellent sensitivity and
outstanding specificity for prostate cancer when it compared to other pet
agents .
 Some studies have shown that PSMA-Based tracer Is Superior to
Conventional Imaging for detection metastatic lesion.
 Molecular imaging with PMSA based agents have limited role in primary
disease when it compered with MRI but they are able to detect the more
clinically significant high-grade and larger-volume tumors (Gleason score
8 and 9) with higher specificity than MR imaging.