Urology

1. PET SCAN IN UROLOGY
Seminar by
Dr. Noushim Akram Huda

2. INTRODUCTION:
Molecular imaging
• Defined by Society of Nuclear Medicine
“the visualization, characterization, and measurement of biochemical process at the
molecular and cellular levels in humans and other living systems”
• Discipline intersection of molecular biology and in vivo imaging
• Visualisation of the cellular function
• Follow up of the various molecular process
• Without perturbing them
• Diagnosis of disease such as- cancer
neurological
cardiovascular disease
newer applications like infection and inflammation

3. • Radionuclides that emit positrons can be detected with positron emission
tomography ( PET)
• Emitted positrons travel a short distance before colliding with a nearby electron,
causing annihilation event that leads to the release of two 511 KeV photons
travelling 180 degree apart.
• Images are constructed after the coincident detection of these two high energy
photons.
• Positron Imaging Tomography and Computed Tomography is the combination of
functional imaging as well as anatomical imaging.

5. • In the past decade, there has been significant progress in the field of Nuclear
Medicine in the diagnostic evaluation of urological malignancies, mainly because of
the technological advance in PET/CT scanners and the increasing variety of positron-
emitting radiopharmaceuticals such as 18F-FDG, 68Ga-PSMA, 18F-PSMA, 18F-
sodium fluoride, and others.
• Depending on the radiotracers used, PET offers diagnostic information based on
glucose, choline or amino acid metabolism and has been applied to imaging tumour
cell proliferation and tissue hypoxia in urologic malignancies.
• The radiopharmaceutical most commonly used for PET in oncology is 18F-FDG, an
analogue of glucose that is preferentially taken up and trapped inside malignant cells.

6. •PET-MRI:
• In recent years, there has been increasing interest in the development of integrated
PET/MRI systems
• Advantages over PET-CT
• improved soft-tissue contrast,
• the availability of sophisticated MRI sequences, such as
• diffusion and perfusion imaging,
• functional MRI,
• MR spectroscopy
• significant decrease in radiation exposure,

7. • The diagnostic performance of FDG-PET is hampered by the renal excretion of FDG
and by the low metabolic activity often seen in tumours such as prostate cancer.
• However, new PET tracers, including radiolabelled choline, acetate and others may
offer alternatives with improved diagnostic abilities

12. • Prostate cancer
• Renal cancer
• Urinary bladder cancer
• Testicular cancer
• Penile cancer
• Adrenal cancer
• Retroperitoneal fibrosis
• Infected renal cyst

13. PROSTATE CANCER

14. 1.Diagnosis of primary cancer
2.Staging of prostate cancer
3.Evaluation of rising PSA post therapy
4. Response to treatment
5. Therapy with 177 Lu-PSMA,225 Ac- PSMA

15. • Prostate cancer is the most common cancer, and the second most common cause of
cancer-related deaths in men in the US.
• Despite advances in prostate cancer screening, surgery, hormone-related therapies,
and chemotherapies, approximately 27,000 men still die of metastatic prostate
cancer each year in the United States.
• The majority of the patients diagnosed with early-stage prostate cancer will undergo
treatment by either radical prostatectomy or radiation therapy to cure their disease.
• Unfortunately, approximately 30% of these patients recur biochemically based on
rising serum PSA levels.

16. • Many different PET tracers are being actively investigated for use in PET/CT
imaging for prostate cancer.
• It is well known that the ability of 18F-FDG PET to detect cancer is based on
increased expression of cellular membrane glucose transporter 1 (GLUT1) and
enhanced hexokinase II enzyme activity within tumor cells.
• Preclinical studies have examined the expression of GLUT1 in prostate cancer cell
lines and found that it is higher in those that are poorly differentiated in
comparison with well-differentiated hormone-sensitive cell lines.
• This suggests that GLUT1 transporter expression increases with increasing disease
grade and may explain the higher 18F-FDG accumulation in castration-resistant
than in castration-sensitive tumors and the modulatory effect of androgen on the
glucose metabolism of castration-sensitive tumors.

17. • Various PET tracers have been used for PET/CT imaging.
• FDG:
• 18F-FDG PET/CT is of limited value for detection and localization of primary
prostate cancer and initial staging of disease,
• tumour uptake levels that can overlap with those of
• normal tissue,
• prostatitis,
• benign prostatic hyperplasia (BPH).
• useful for detection of
• aggressive disease,
• evaluation of tumour extent,
• response of metastatic disease to treatment,
• prognostication in patients with castration-resistant tumours

18. • Choline:
• 11C-choline and 18F-fluorocholine are well established tracers
• High false positivity for detecting primary lesions
• high-grade prostatic intraepithelial neoplasia,
• prostatitis
• BPH
• normal tissue
• Detection of locoregional LN metastasis,
• Identification of local recurrence
• Restaging of biochemically recurrent prostate cancer

19. • Acetate:
• Newer modality
• 11C-acetate PET/CT has been useful for identification of disease recurrence
• Still under trial for use in detection of primary lesions
• NaF:
• PET with 18F-sodium fluoride (18F-NaF), a highly sensitive radiotracer for skeletal
metastases
• Less false positives
• Combined administration of 18F-NaF and 18F-FDG in a single PET/ CT scan for
cancer detection has been advocated for detection of both extra-skeletal and skeletal
lesions

20. • FDHT:
• 16β-18F-fluoro-5α-dihydrotestosterone (18F-FDHT)
• Assessment of growth and proliferation of prostate carcinoma as well as
modulation of androgen status
• In assessment of treatment response where androgen therapies are used as a
primary modality

21. • FACBC: 18 F Fluciclovine
• anti18F-fluorocyclobutane-1-carboxylicacid (anti-
3-18F-FACBC)
• detection of prostate cancer relapse

22. PSMA PET/CT in prostate cancer
• The prostate-specific membrane antigen (PSMA) is a transmembrane glycoprotein
expressed in the epithelium of the prostate cell and overexpressed (100 to 1000
times more) in the epithelium of the prostate cancer cells.
• 90 % of prostate cancers are positive for PSMA.
• Expression is reflective of castrate resistance.
• 68Ga- PSMA PET CT most sensitive technique for primary diagnosis, staging,
response to treatment and detection of recurrence at low PSA levels

23. • PSMA may be applied as a theragnostic agent. Theragnostic is based on a therapeutic
intervention after diagnostic imaging to verify the presence of a biological target.
• The critical aspect of theragnostic is that the choice of patients for a radio-targeted
treatment is based on imaging of the same target area, closely linking imaging and
therapeutic intervention.
• For example, PSMA PET/CT imaging will help determine the eligibility of
radionuclide treatment with 177Lu-PSMA.
• Current NCCN and EAU guidelines have different indications for PSMA
PET/CT. For example, NCCN guidelines do not recommend PSMA PET/CT
imaging and EAU guidelines suggest PSMA PET/CT imaging only in the
biochemical recurrence setting.

24. Diffuse Uptake

25. Intense – uptake- high SUV -cancer

27. Treatment with 177 LU-PSMA

28. PSMA PET/CT for detection of the primary prostate cancer:
• The most valuable tool for identifying clinically significant prostate cancer is currently
multiparametric magnetic resonance imaging (mpMRI).
• However, the PROMIS trial has demonstrated that approximately 25% of men with a
negative mpMRI will harbor clinically significant prostate cancer.
• On the other hand, PSMA expression correlates with the pathology grade group, with
higher-grade tumors showing increased PSMA staining.
• Therefore, PSMA PET/CT imaging can objectively determine the aggressiveness of a
detected prostate tumor because of the ability to quantify the radiopharmaceutical
uptake present, which is linked to PSMA protein expression by the tumours.

30. PSMA PET/CT for primary staging of prostate cancer:
• Conventional imaging studies routinely performed to detect metastases in primary
staging of prostate cancer are bone scan and CT of the abdomen and pelvis.
• These conventional imaging studies are strongly recommended if performed in
patients with high-risk neoplasms (i.e., Gleason score of 8–10, ISUP grade 4/5 and/or
PSA levels above 20 ng/ml and/or tumors ≥ T2c), although even in high-risk
neoplasms the sensitivity of conventional imaging studies might be low.
• Even in unfavorable intermediate risk neoplasm (patient with Gleason score 4 + 3,
ISUP grade ≥ 3), conventional imaging are discouraged in the primary staging, with
weak evidence recommendation according to EAU.

31. • Lymph node staging
sensitivity 84 %, specificity 82%( CT- 65%, 76%)
• PSMA negative and histopathology positive nodes are small ( mean size < 3 mm
and have micro metastasis
Nodes < 5 mm are usually difficult to detect
• CT/ MRI use size criteria for calling a node metastatic. Thresholds vary from 8-15
mm. 80% metastatic nodes are < 8 mm
• Pararectal , mesenteric and inguinal node metastases are often seen on PSMA
PET-CT

32. • 68Ga-PSMA PET/CT also identifies bone metastases in patients with intermediate
and high-risk prostate cancer and varies according to the PSA levels.
• For instance, 68Ga- PSMA PET/CT can identify bone metastases in 21% of
patients with PSA levels < 10 ng/ml; in 41% of patients with PSA levels of 10–20
ng/ml and also in 41% of patients with PSA ≥ 20 ng/ml.
• 68Ga-PSMA PET/CT might have an auspicious role for primary staging as the
detection rate of small metastases (when compared to conventional imaging
studies) are high.
• The 2020 EAU and NCCN guidelines do not yet recommend PSMA PET/CT for
primary staging of intermediate and high-risk prostate cancer patients due to high
cost and lack of randomized controlled trials evaluating the management and
outcome of patients with (and without) metastases detected by choline PET/CT,
PSMA PET/CT, and MRI.

33. PSMA PET/CT in biochemical recurrence of prostate cancer:
• The identification of metastases in patients with biochemical recurrence is a
challenge for anatomical imaging methods.
• After radical prostatectomy, the recurrence of prostate cancer usually has an
estimated volume < 1.0 cm3 for PSA values < 3.5 ng/ml, which makes it extremely
difficult to detect lesions using anatomical methods.
• Whole-body CT has a sensitivity of only 12.5% in patients with PSA < 1.0 ng/ml
and MRI sensitivity of 12.9% in patients with PSA ≤ 0.5 ng/ml.

34. Staging of recurrent prostate cancer
• Biochemical recurrence is suspected when Sr PSA levels are > 0.2 ng/ml
• Salvage radiotherapy is most effective with treatment is initiated early in the stage
of disease with Sr. PSA <0.5 ng/ml
• Most current modalities yield result only when Sr. PSA exceeds 10

36. • So PSMA PET/CT is currently recommended by the EAU guideline since it
presents high sensitivity to detect metastases even when serum PSA levels are
quite low (from 0.2 to 0.5 ng/ml).
• The higher the serum PSA levels, the greater the success of detecting relapse.
• The identification of lymph node metastases is feasible even when smaller than 0.8
cm.
• Bone metastases are also easily detected with radiolabeled PSMA PET/CT in
patients with biochemical recurrence.
• Therefore, radiolabeled PSMA PET/CT in biochemical recurrence has significantly
affected patient management, ranging from 50 to 60%.

37. PSMA PET/CT for radiotherapy planning of prostate cancer:
• In patients that undergo radiotherapy with curative intent, PSMA PET/CT may
identify metastases outside the conventional radiotherapy treatment field in up to
48% of patients.
• In a study, among the 108 patients that underwent 68Ga-PSMA PET/CT for
primary staging, 15% of them received higher radiotherapy dose or planned
radiotherapy volume, due to the 68Ga-PSMA PET/CT scans results.
• Currently, PET/CT with radiolabeled PSMA can assist in the delineation of the
tumor volume to improve RT planning. Although MRI is the gold standard for
delineation of the tumor volume, its interpretation is difficult and may
underestimate the actual tumor mass.
• PET/CT with radiolabeled PSMA seems to bring more accurate information in
the personalized RT planning of patients with primary prostate tumors.

38. A 67-year-old patient with a 10-year history of
prostate cancer treated with radiotherapy to the
prostate bed underwent bone scintigraphy
with SPECT/CT due to biochemical recurrence.
His PSA at the time of the bone scintigraphy was 4.0
ng/dl.
The(a) whole-body bone scan in the anterior and
posterior projections and (b) SPECT/CT images do
not demonstrate areas of abnormal uptake consistent
with bone metastases, only regions of remodeling due
to degenerative processes.
Because the bone scan was negative, on that same
week, the patient was submitted to a 68Ga-PSMA
PET/CT.
The(c) MIP PET image shows a single focal uptake in
the thoracic region, and the
(d) fused sagittal 68Ga-PSMA PET/CT image shows
that the focal uptake corresponds to bone metastasis in
the thoracic spine (dotted arrow)

39. • A patient underwent a 68Ga-PSMA
PET/CT due to biochemical recurrence of
prostate cancer. The
(a) MIP PET image demonstrates
increased uptake in the right acetabulum and
iliac bone (arrow) and in the penis, which is
better seen in the sagittal
(b) CT and
(c) fused images.
• Penile metastases from prostate cancer are
rare.
• PSMA-avid lesions have been described
as a single focal lesion, multiple focal lesions,
and diffuse lesions.
• The identification of penile metastases is
essential for adequate treatment and
symptom-relief.

40. • A 68-year-old patient underwent 18F-PSMA PET/CT
due to biochemical recurrence of prostate
adenocarcinoma (Gleason 4 + 4), treated 5 years ago
with radical prostatectomy.
• All conventional imaging studies were negative. His
PSA level at the time of the 68Ga-PSMA PET/CT scan
was 8.90 ng/dl. The
(a) MIP PET image demonstrates
increased 18F-PSMA uptake in bone metastases in the rib
cage (dotted arrow) and the right iliac bone (arrowhead).
• The bladder has no excretion of 18F-PSMA, making it
possible to reveal a focus of increased 18F-PSMA
uptake adjacent to or in the bladder. The
(b) CT and
(c) fused 18F-PSMA PET/CT images demonstrate that
the focus of increased 18F-PSMA uptake near the bladder
corresponds to the infiltration of the posterior wall of the
bladder (arrows).

41. Adrenal Cancer
• Malignant adrenal disease tends to have higher 18F-FDG uptake compared with
benign adrenal lesions.
• A multicentre study demonstrated that 18F-FDG PET/CT showed the better
diagnostic accuracy of diagnosing primary adrenal malignancy (adrenocortical
carcinoma, malignant pheochromocytoma, neuroblastoma, and lymphoma) than
contrast-enhanced CT.
• The diagnostic performance of 18F-FDG PET/CT for differentiating metastatic
adrenal tumours from adrenal adenoma is high (sensitivity, specificity and
accuracy are 82%, 92%, and 90%).
• The combination of 18F-FDG PET/CT and adrenal protocol CT can improve
the 18F-FDG PET/CT or adrenal protocol CT diagnostic accuracy for
differentiation of metastatic adrenal tumors from adrenal adenoma, reducing
false-positive cases.

42. TESTICULAR CANCER

43. • TESTICULAR CARCINOMA:
• Seminomas exhibit higher uptake than non-seminoma testicular cancers, although
the difference is not significant.
• Evaluation of residual masses from non- seminomatous tumors with FDG PET/CT
is not recommended as it harbor residual foci of mature teratoma
• limitations to 18F-FDG PET:
• (1) lesions of <1 cm are often not detected
• (2) Mature teratoma cannot be distinguished from necrosis or fibrosis
• (3) There should be a minimum of 6 weeks between the end of chemotherapy
and acquisition of an 18F-FDG PET/CT scan to avoid any false-positive
• Current guidelines from the EAU endorse the use of 18 F-FDG PET imaging is
in the detection of residual seminomatous germ cell tumors after chemotherapy

44. Fig.
• Fluorine-18 fluorodeoxyglucose (18F-
FDG) PET/CT is useful for staging
and restaging of seminoma in patients
treated with chemotherapy.
• This patient presented with a right-
sided seminoma with bulky right-sided
retroperitoneal lymph nodes.
• PET/CT after chemotherapy shows no
uptake in the previously positive nodal
region.

45. • Patient with classic seminoma of the left
testicle undergoing orchiectomy.
• 18F-FDG PET/CT was performed for
primary staging.
a The MIP PET image demonstrates uptake
in the enlarged hypermetabolic
retroperitoneal lymph node metastasis
(arrow), which can be better appreciated in
the b axial fused PET/CT and c axial CT
image (thick arrows)
• In the MIP PET image, the distribution of
retroperitoneal metastases is exclusively
along the paraaortic chain, typical of left
testicular neoplasia.

46. • A patient diagnosed with classic seminoma of the
right testicle underwent 18F-FDG PET/CT for
primary staging.
a The MIP PET image and
b the coronal fused PET/CT image demonstrate an
enlarged hypermetabolic retroperitoneal inter aorto-
caval lymph node metastasis (arrows).
• After chemotherapy, although a dedicated CT
showed a significant reduction in the dimensions
of this retroperitoneal lymph node, it was not
possible (only by CT) to determine if there was
still a viable tumor.
• The 18F-FDG PET/CT performed after treatment
clarified the diagnosis.
c The MIP PET image and
d the coronal fused PET/CT image demonstrate a
reduction in the volume of the metastasis and
absence of metabolism (thick arrows)

47. RENAL CELL CARCINOMA

48. PET/CT in renal cell carcinoma (RCC):
• Renal cell carcinoma (RCC) represents 3% of all malignant neoplasms, and it is
the third most frequent among genitourinary neoplasms after prostate and
bladder cancers
• The clear cell variant is the most common and has the greatest metastatic
potential compared to the others.
•
• At initial diagnosis, 20–30% of patients already present distant metastases and
the main sites of metastases are the lungs (45%), regional lymph nodes(22%),
bones (30%), liver (20%), adrenal (9%) and brain (8%), in addition to neoplastic
thrombi.
• Contrast-enhanced CT provides accurate information for detection and local
staging of renal cell carcinoma

49. • Extrarenal metastasis is detected more easily than renal lesions by 18F-FDG PET/CT
• Sensitivity of 18FFDG PET or PET/CT was 79 % for intrarenal tumors and 84 % for
extrarenal metastases
• Higher uptake value on 18F-FDG PET was associated with aggressive behavior
metastatic potential and early relapse.
• PET was able to predict not only the duration of response to TKIs, but also survival
duration and early assessment by 18F-FDG PET/CT provided useful information for
determining individual patient management strategies

50. FDG PET/CT for diagnosis of primary tumor
• CT and MRI are routinely used in the diagnosis and local staging of RCC.
• Although CT and MRI are highly sensitive for detecting renal lesions, their low
specificity often makes the differential diagnosis between benign and malignant
neoplasms difficult, especially in small lesions or those with atypical morphology.
• The metabolic analysis of the tumor may be useful when a histological evaluation is not
possible because the patient’s clinical conditions do not allow for biopsy nor surgical
resection of these lesions.
• The accuracy of 18F-FDG PET/CT for the detection of RCC is quite controversial in the
literature with sensitivities ranging from 47% to 89% and specificity from 67 to 87%.

51. The three factors that reduce the ability to detect and characterize RCC by 18F-FDG
PET/CT are the following:
1. Physiological renal excretion of the radiotracer although this fact may be overcome
by delayed imaging with hyperhydration and diuresis;
2. Variable expression of GLUT-1;
3. Some benign primary neoplasms of the kidney (angiomyolipomas and
oncocytomas), as well as infections and vasculitis, are 18F-FDG-avid.
• Therefore, 18F-FDG PET/CT should be indicated to detect the primary lesion or for
primary staging of RCC in selected cases, such as in patients with locally advanced
neoplasms and suspected metastases, and preferentially with the addition of an
intravenous contrast agent.

52. Male patients with a prior history of tuberculosis
developed a fever of unknown origin. A renal mass,
identified on ultrasound (US) and confirmed on
magnetic resonance imaging (MRI), was equivocal for
renal neoplasia. He underwent an FDG PET/CT for
diagnostic clarification. The
(a) MIP PET image showed a focal region
of increased uptake in the upper pole of the left kidney
and no other regions of uptake in the body.
The (b) CT scan images identified the complex renal
cyst, consistent with the renal mass identified by US
and MRI, and infection could not be ruled out.
c The PET image demonstrates a hypermetabolic lesion
in the upper pole of the left kidney, the uptake is higher
than the normal renal parenchyma and also a central
portion of hypometabolism. These findings were
consistent with renal infection. The biopsy confirmed
infection.

53. FDG PET/CT for staging and restaging of RCC:
• Current guidelines recommend against the routine use of 18F-FDG PET for
staging or follow up of RCC , as the clinical benefits remain unclear, and most
cases of RCC are clear cell type which shows lower levels of FDG uptake.
• On the other hand, 18F-FDG PET/CT is the preferred method to identify RCC bone
metastases, as a systematic review has shown the sensitivity to be quite high (94%).
• Bone metastases from RCC are, in general, purely lytic. Hence, conventional bone
scintigraphy (which identifies osteoblastic metastases) is not, currently, the adequate
imaging method to identify bone metastases from RCC.

54. A male patient underwent nephrectomy
due to RCC. He was treated with
tyrosine kinase inhibitors due to a
retrocaval lymph node
metastasis.
a The CT image performed after
treatment demonstrates that the
retroperitoneal lymph node metastasis
was still enlarged, with no volume
reduction (arrow).
• FDG PET/CT was requested to
elucidate the viability of the
metastasis.
b The coronal fused FDG PET/CT
image denotes persistent mild uptake in
the retroperitoneal lymph node (arrow),
indicating that the metastasis is still
metabolically active or viable.

55. FDG PET/CT for prognosis and therapy response in RCC:
• There is a significant direct correlation between the degree of 18F-FDG uptake
[measured by SUV max] of the primary RCC and metastases with the degree of
aggressiveness of the neoplasm.
• The higher the 18F-FDG uptake, the lower the overall survival.
• This prognostic role of FDG PET/CT should be emphasized since a recent study
has shown that a negative FDG PET/CT scan is indicative of superior cumulative
survival in 5 years and higher progression-free survival in 3 years.
• Conventionally, RCC does not respond well to cytotoxic chemotherapy and
radiotherapy, requiring other drugs.

56. • Novel radiotracers targeting the cell surface protein carbonic anhydrase IX
(CAIX)—a molecule that is near universally expressed by clear cell RCC but not
by other renal tumor histology's—are likely in the future to play a large role in
molecular imaging of RCC.
• To date, the most promising agent targeting CAIX is the monoclonal antibody
girentuximab, also known as G250. The application of CAIX-based PET imaging
that has been most actively pursued is the differentiation of localized clear cell
RCC apart from other renal tumor histologies .
• In a large phase III trial, PET imaging with 124 I-girentuximab PET/CT had a
sensitivity of 86.2% and a specificity of 85.9% for differentiating localized clear
cell RCC from other renal tumor histologis. This outperformed contrast-enhanced
CT, which had a sensitivity of 75.5% and a specificity of 46.8% . Despite these
promising results, girentuximab is not yet approved for routine human use, as the
results of a confirmatory phase III trial are pending.

57. PSMA PET/CT in RCC:
 PSMA is highly expressed on the cell surface of the microvasculature in several solid tumors and
this might be the cause of pitfall in prostate cancer imaging.
 RCC expresses PSMA in its cell surface, which has stimulated investigations evaluating the role of
PSMA PET/CT in RCC.
 RCC may propagate contiguously, forming thrombi via the renal vein to the inferior vena cava and
reaching the right atrium.
 A study performed immunohistochemical analysis of PSMA uptake in the vena cava thrombus and
renal tumors showed consistently increased expression of PSMA in the vena cava tumors, in
comparison with the renal tumor mass.
 This study opens a new path for investigating PSMA PET/CT as a biomarker of neo-angiogenesis
for diagnostic and possibly therapeutic interventions.

58. Urothelial cancer

59. PET/CT in urothelial cancers
• Bladder cancer is the most common malignancy of the urinary tract and the
ninth most common malignancy in the world.
• Urothelial (transitional cell) carcinoma (UCC) is considered a solid malignant
tumor and is the predominant histological type.
• UCC may involve the lower urinary tract (bladder and urethra) and account
for 90% of all bladder cancers while the upper urinary tract carcinoma
(UUTC) is uncommon, may involve the calyces, kidneys, and ureters and
accounts for only 5–10% of UCs.
• Despite prompt and aggressive treatment, metastases from UCC appear within
2 years and are mainly located in pelvic and retroperitoneal lymph nodes,
bones, liver, and lungs.

60. FDG PET/CT in urothelial cancers
• Urothelial cancer cells have high avidity for 18F-FDG; the more aggressive the
tumor, the higher the uptake of 18F-FDG.
• Currently, the diagnostic workup of urothelial and bladder cancers does not
include 18F-FDG PET/CT.
• Despite the high uptake (consequently sensitivity) to detect urothelial cancer,
one of the main reasons why 18F-FDG PET/CT has not been widely used is
because of one of the limitations regarding physiological elimination of 18F-
FDG by the urinary system, which might interfere with the visualization of
primary cancer and locoregional lymph nodes.
• However, this limitation of 18F-FDG may be overcome by performing
additional delayed images after venous injection of furosemide, hyper-hydration,
and diuresis, increasing the sensitivity to detect lesions from 85 to 96%.

61. A patient with urothelial carcinoma of the bladder was
staged with CECT.
a, b The CECT images demonstrated two areas of mild
wall thickening in the left ureter (equivocal for
malignancy) that persisted after neoadjuvant
chemotherapy (arrows).
c Routine whole-body FDG PET/CT performed
before surgery to elucidate the equivocal finding, as
expected, did not reveal 18F-FDG-avid lesions; only
physiologic tracer accumulation/excretion in the left
dilated ureter and the bladder (arrows).
D The FDG PET/CT protocol consisting of delayed
images after hyperhydration and diuretics demonstrated
foci of hypermetabolism in
the bladder consistent with primary multifocal cancers
(red arrows) and two foci of metastatic spread in the
ureter (blue arrows).
FDG PET/CT findings completely altered the surgical
treatment; the postoperative histopathology findings
confirmed high-grade urothelial carcinoma in the bladder
and metastatic spread in the ureter.

62. PENILE CANCER

63. • Squamous cell carcinoma of the penis shows high levels of 18F-FDG uptake.
• One application of 18F-FDG imaging in patients with penile cancer is inguinal
lymph node staging. More specifically, 18F-FDG PET offers a reliable method for
confirming the presence of metastatic disease and determining the relative extent of
nodal involvement in patients with palpable inguinal lymph nodes.
• A meta-analysis by Saeghi et al. reported a sensitivity of 96.4% for detecting nodal
metastases among patients with palpable groin nodes. Thus, in this high-risk
population, 18F-FDG is useful for assessing extent of disease and steering patients
with large-volume nodal involvement toward neoadjuvant chemotherapy.
• In contrast, the utility of 18F-FDG PET for primary tumor staging and the evaluation
of patients with nonpalpable inguinal lymph nodes is somewhat limited.
• It is worth noting that although 18F-FDG PET can be used to detect distant sites of
penile cancer, the literature on this topic is somewhat scarce, and little is known
regarding the clinical benefits of this practice.

64. Retroperitoneal fibrosis

65. Infected renal cyst

66. Conclusion
• PET/CT imaging has an established role in the diagnosis of some urological
malignancies and, in specific clinical indications, is used because of the enormous
potential to alter patient management.
• Besides the established roles of FDG PET/CT, the advances of novel radiotracers for
PET/CT imaging in urological malignancies, such as PSMA PET/CT, allows
evaluation in the settings of staging, recurrence, response to therapy and prognosis.
• Furthermore, PET/CT imaging helps in planning and assessing response to treatment
in theragnostic.
• Molecular images identify early changes that conventional anatomical studies cannot,
and for this reason, the images performed on PET/CT are becoming increasingly
indispensable in specific clinical situations and with precise indications according to
the type of urological malignancy.