This document discusses the role of various imaging modalities in detecting and staging prostate cancer, including transrectal ultrasound, MRI, MR spectroscopy, CT, nuclear medicine scans, and PET imaging. It provides details on what each modality can visualize, its accuracy for assessing the primary tumor and metastatic disease, and when it is recommended in prostate cancer evaluation, treatment planning, and follow-up.

1. Oncoimaging: prostate cancer
Topic on Radiotherapy
12.06.2014
Thorsang R1

4. Outline
• Introduction
• Imaging guideline
• Use of each imaging method
– Transrectal US
– MRI
– MR spectroscopy imaging
– Dynamic contrast-enhanced MRI
– Radionuclide bone scanning
– PET imaging
• Use of imaging in treatment planning
– Prior to surgery
– In radiation oncology
– In treatment follow-up
• Conclusion

5. Prostate cancer

6. Introduction
• TNM staging, Gleason score, and PSA level
– Predict pathologic stage and prognosis
• Risk stratification
– To maximize cancer control and minimize
complication
• Treatment alternatives
• Imaging
– Guide treatment selection
– Treatment planning

7. Treatment alternative
• Deferred therapy (watch and wait)
• Radiation therapy
– external-beam irradiation, brachytherapy
• Surgery
– radical retropubic/laparoscopic prostatectomy
• Hormone therapy (androgen ablation)
• Chemotherapy
• Focal ablative therapy
– cryotherapy, RF ablation, focused ultrasound
• Prostate cancer vaccine

8. Role of imaging in prostate cancer
detection and staging
• Fairly limited role
– Critical role in the past
– Under debate
• Sensitivity and specificity: decreasing role of
imaging
– Low-risk prostate cancer requires no imaging
– high-risk group progresses to treatment
• Largely used to evaluate metastatic disease

9. NCCN clinical practice guideline
v.1.2014

10. 1. Assess the primary or recurrent tumor
- within the prostate gland
- tumor size
- Multifocality
- extracapsular extension
- seminal vesicle extension
- neurovascular bundle involvement
- bladder involvement
Use of imaging

11. 1. Assess the primary or recurrent tumor
2. Assess metastatic disease (l.n., bone)
3. Guide prostate or suspicious lymph node
biopsies
4. Functional or metabolic
- Assess tumor aggressiveness
Use of imaging

12. Evaluation of the Primary Tumor
• Transrectal Ultrasonography
• MR

13. • The most common for direct visualization
– real-time imaging, portability, ease of use, and low cost.
• Imaging-guided
– prostate biopsies
– cryotherapy
– Hyperthermia
– photodynamic therapy
– brachytherapy seeds into the prostate
• Visualize intraprostatic zonal anatomy
– The peripheral zone showing slightly increased
echogenicity compared with the central gland
• Prostate carcinoma
– Hypoechoic area within the peripheral zone
Transrectal Ultrasonography

14. Transverse image
pz - slightly more
echogenic
n - more hypoechoic
Sagittal image
a hypoechoic nodule
>> suspected CA

17. Transrectal Ultrasonography
• Criteria for extracapsular extension on
transrectal US scans
– bulging or irregularity of the capsule adjacent to a
hypoechoic lesion
– The length of the contact of a visible lesion with
the capsule
– Seminal vesicle invasion:
• Hypoechoic lesion at the base of the prostate into a
seminal vesicle
• Asymmetry of the seminal vesicles or solid hypoechoic
masses within the seminal vesicles

18. Transrectal US: the cons
• Not sensitive or specific for the detection of
prostate carcinoma
• Color Doppler and power Doppler imaging
– Do not substantially add accuracy to the technique
– High vessel density predicts a slower rate of decline of
PSA with radiation treatment
• Also limited accuracy for the detection of
extraprostatic extent of tumor
– no role in the evaluation of metastatic disease.
– US-guided needle biopsy of suspicious nodes found on
CT or MRI is useful for confirming metastatic disease.

19. • US contrast
– Show hypervascularity--tumor angiogenesis
– Fleeting, expertise is required
– Contrast-enhanced US improves the positivity of directed
biopsies vs random biopsies
– Because contrast-enhanced ultrasonography detects
hypervascularity, the detected tumors tend to have higher
Gleason grades
– Future development: microbubble contrast
• Could play a major role in cancer detection
• Elastography
– Relatively new technique
– Measures tissue stiffness using US
– Cancer tissue is generally stiffer
– No high sensitivity and specificity
Transrectal US

20. MRI
• Provides more
information
• Recommended
– Only if suspected
cancer despite
negative US and Bx
• Tissue properties
– Diffusion
– Enhancement
– Spectroscopy

21. • Optimal MRI of prostate cancer for detection and
local staging
– Requires endorectal coil and pelvic phased-array coil
on a mid- to highfield-strength magnet
• Images at 1.5 and 3 T providing images of a
similar quality
• Most effective for tumors located in the
peripheral zone
• When combined with MR spectroscopic imaging,
can be used to detect tumors in the transition
zone
MRI

22. MRI
• Higher signal-to-noise,
high resolution images
• T1 abdomen and pelvis
– for lymph node disease
• Smaller field-of-view
(higher resolution) T1
and T2
• Additional sequences:
DWI, DCE, MR
spectroscopy
Phased-array coil +/-Endorectal coil

23. T2

24. Prostate Cancer Imaging
• On DWI
– Prostate carcinoma
• restricted diffusion
– Hemorrhage vs
tumor in the
peripheral zone
• With contrast
– Early enhancement
– Early washout
DWI
ADC
Early Gd

25. MRI with contrast
• Variable enhancement
• early nodular enhancement and
early washout
-> highly predictive of prostate
T2
Early Gd
Late Gd

26. MRI
• Evaluation of extracapsular invasion
– transverse sections are essential
– Ideal: a combination of transverse and coronal
– Addition of sagittal images--evaluation of tumor at the
apex and base
– Combined transverse, coronal, and sagittal sections--
evaluation of seminal vesicle and bladder neck invasion
• Extracapsular extension
– protrusion through the prostate capsule
– capsular thickening
– Nodularity
– bulging of the capsule

28. MR Spectroscopy
• Allows assessment of tumor metabolism
• Choline and citrate
• The normal prostate gland produces
– high levels of citrate
– low levels of choline
• Prostate cancer: higher cell membrane turnover
– Higher levels of choline
– Increased choline: citrate
• Improves tumor localization within the peripheral zone
• Preliminary evidence: key molecular markers—
histologic prediction of prostate cancer aggressiveness

31. MRI: accuracy of staging
• The accuracy for extracapsular extension is between
70% and 80%.
• With the identification of seminal vesicle invasion is
more accurate.
• DWI and DCE imaging may provide small incremental
increases in accuracy.
• MRI is more accurate in patients at intermediate or
high risk
• The detection rate of tumors is also dependent on size,
with tumors smaller than 2 cm unlikely to be detected.

32. Evaluation of Prostate Cancer
Metastases
• Patients need evaluation when
– High-risk group with a new diagnosis
– After biochemical failure following treatment
• Modalities
– CT
– MR
– Nuclear medicine study

33. CT
• Quick evaluation for metastases
in the chest, abdomen, or pelvis.
• Efficient at identifying enlarged
lymph nodes
• Poor tissue contrast within the
prostate
– evaluation of the intraprostatic
tumor is limited
• Detect bone metastasis esp.
osteoblastic
– Recommended with a very high
pretest probability

34. • Similar to CT--evaluate lymphadenopathy and
metastases
-> similar diagnostic information
• DWI of lymph nodes--more specific assessment
than size criteria
– reflecting greater cell density
• DCE properties of lymph nodes
– stronger and more rapid enhancement
• Superparamagnetic contrast: lymph node uptake
– 82% sensitivity (vs 34% in CT)
– off-label use of ferumoxytol—now under investigation
MRI

35. MRI
• Evaluating for bone metastases by MRI
– T1
– short TI inversion recovery imaging
– DWI
• These survey examinations may be more
sensitive than PET/CT or scintigraphy in
identifying metastases.

36. Nuclear Medicine
• Bone scan has no role in prostate cancer detection or
local staging
• Reserved for patients with
– Suspected osteoblastic skeletal metastatic disease
– A rising PSA without demonstrable bulky distant
metastatic disease
– Skeletal metastatic disease following
prostatectomy

37. • Bone scan
– A focal area of increased tracer uptake, usually in the axial
skeleton -> osteoblastic bone response to tumor invasion
– A focal area of reduced uptake -> extensive damage to bone
with little osteoblastic response
– Sensitivity: 95% in patients with PSA > 20 ng/ml
– Low specificity: degeneration, autoimmune, infection
– Assess the response to treatment
• “flare” phenomenon
– uptake initially increases after chemotherapy or
hormone therapy
– peaking at 6 weeks after treatment (bone turnover
increases as part of the healing process)
Nuclear Medicine

38. • PET imaging
– F-18 (18F) fluorodeoxyglucose (FDG)
– Cancers have increased metabolism and utilize the
less-efficient glycolytic pathway, both of which lead to
increased glucose analogue uptake
– Tumor detection-- low sensitivity
– No difference in tracer uptake between BPH and CA
– Evaluation of pelvic lymph node metastases
• Not helpful owing to excreted tracer in the urinary bladder
that caused obscuration of the pelvis.
Nuclear Medicine

39. • PET/CT
– May demonstrate tumor location in the prostate bed and to
better assess pelvic lymph node disease.
– allows differentiation between tumor and tortuous ureter or
bowel in the midabdomen or pelvis
Nuclear Medicine

41. • New tracers, which are currently under clinical
investigation.
– C-11 methionine
• differentiates tumor from normal tissue due to
elevated protein synthesis
• minimal interference from the bladder
– C-11 acetate
– C-11 choline
Nuclear Medicine

42. • New tracers, which are currently under clinical investigation.
– In-111
• particularly the pelvic sidewall and retroperitoneal lymph
nodes
• directed against prostate-specific membrane antigen (PSMA)
on the surface of prostate cancer metastases
• Sensitivity rate ranges from 62% to 75%
• Limited by nonspecific uptake in bowel, vasculature, bone
marrow, and normal prostatic tissues
• In the future, molecular imaging will influence prostate cancer
more and more as new tracers are developed
Nuclear Medicine

43. Imaging prior to surgery
• MRI
– improved surgical planning for high-risk patients
– decision not to resect neurovascular bundles in
other patients
– predict substantial intraoperative blood loss,
– longer than average (14-mm) membranous
urethra lengths
• a more rapid return to complete continence

44. Imaging in radiation oncology
• Development of the image-based computer treatment
planning systems during the 1980s
– allowed CT image data to be incorporated into radiation
therapy treatment plans
• Define target and nontarget tissue structures
• Calculation and display of 3D dose distributions
– Beam’s-eye-view displays
– Analysis and evaluation of structure-specific dose-volume
data
• Treatment of prostate cancer
– Use of conventional radiation therapy dose levels of 65–70
Gy
– 2D and 3D

45. • IMRT
– deliver high doses to the prostate with enhanced
precision
– generate treatment fields with varying radiation
intensities within each beam
– steep dose gradients at the transition to normal
tissues
– Reduced rectal toxicity
– permitted tumor dose escalation to previously
unattainable levels (up to 86 Gy)
– permit simultaneous delivery of different dose
prescriptions to multiple target sites
Imaging in radiation oncology

46. • IMRT
– Location, volume, extent, tumor biology (e.g.
tumor aggressiveness, angiogenesis, hypoxia) is
becoming essential
– the combination of x-ray attenuation data from CT
and tissue contrast from MR imaging provides a
powerful planning tool.
Imaging in radiation oncology

47. Imaging for treatment follow-up
• serial PSA and DRE findings are the standard
tools used in monitoring for tumor recurrence
• No need for routine imaging studies if the PSA
level is undetectable and there are no new
clinical findings.
• With an increasing PSA level, the initial study
for metastases is a bone scan.
– however, is rarely positive until PSA levels are
high, around 30 ng/mL

48. • The major goal for prostate cancer imaging in the
next decade
– more accurate disease characterization through the
synthesis of anatomic, functional, and molecular imaging
information.
• No consensus exists regarding the use of imaging for
evaluating primary prostate cancers.
• Ultrasonography is mainly
– biopsy guidance
– brachytherapy seed placement
Conclusion

49. Conclusion
• Endorectal MR imaging is helpful for evaluating local tumor
extent
– MR spectroscopic imaging can improve this evaluation
while providing information about tumor aggressiveness.
• MR imaging with superparamagnetic nanoparticles
– high sensitivity and specificity in depicting lymph node
metastases
– remains restricted to the research setting

50. • CT
– reserved for the evaluation of advanced disease
• PET/CT
– limited in the assessment of primary disease
– gaining acceptance in prostate cancer treatment
follow-up
Conclusion

51. References
• Hedvig, Hricak H., MD, PhD. "Imaging Prostate Cancer: A
Multidisciplinary Perspective." Radiology 243.1 (2007): 28-
53. Radiology. Radiological Society of North America, 01 Apr. 2007.
Web. 09 June 2014.
• Outwater, Eric K., MD, and Jaime L. Montilla-Soler, MD. "Imaging of
Prostate Carcinoma." Cancer Control 20.3 (2013): 161-76. Pubmed.
Web. 05 June 2014.
<http://www.ncbi.nlm.nih.gov/pubmed/23811700>.
• Davis, Charles P., MD, PhD. "Prostate Cancer Pictures Slideshow:
Visual Guidelines to Symptoms, Tests and Treatment." MedicineNet.
MedicineNet, 13 June 2013. Web. 10 June 2014.
• "NCCN Guidelines for Patients® | Prostate Cancer." NCCN Guidelines
for Patients® | Prostate Cancer. NCCN, 2014. Web. 09 June 2014.