Imaging in prostatic patholgy by Dr. Milan Silwal

1. Multiparametric MRI prostate
Dr. Milan Silwal
Resident, MD Radiodiagnosis
NAMS

2. Outline of presentation
• Normal anatomy.
• Imaging modalities.
• Prostatic carcinoma.
• Multiparametric MR imaging.
• PIRADS.
• Conclusions.

3. NORMAL ANATOMY
• The prostate is a tuboalveolar exocrine gland located
inferior to the bladder and anterior to the rectum.
• The conical prostate gland surrounds the uppermost
aspect of the urethra and is enveloped by an incomplete
fibromuscular capsule.
• The anatomic zonal architecture of the prostate gland is
divided into : peripheral zone, central zone, transitional
zone, and anterior fibromuscular stroma .
.

4. Peripheral zone
• Contains approximately 70% of prostate
tissue and is draped around the remainder of
the gland like a ‘catcher's glove’ holding a
baseball.
• Most prostate cancers (70%) arise in the
peripheral zone

5. Transitional zone
• Consists of small areas of peri-urethral glandular tissue.
• It contains only 5% of prostatic tissue in the normal
young man, it is the site of benign prostatic
hypertrophy
• About 20% of prostate cancer arise from this
zone.

6. Central zone
• Consists of the glandular tissue at the
base of the prostate through which course the
ducts of the vas deferens and seminal vesicles
and the ejaculatory ducts.
• The central zone makes up 25% of glandular
tissue
• Approximately 5-8% of cancers arise in this
zone.

7. • Non glandular tissue in anterior portion of
prostate – Fibromuscular stroma.
• The gland contains a base superiorly, a mid-gland,
and an apex inferiorly.
• The base of the prostate is that portion adjacent to
the base of the bladder and the seminal vesicles
• The apex of the prostate rests on the urogenital
diaphragm.

8. Diagram of prostate zonal anatomy. This is the
anatomy in a young man because the transition
zone (white areas) is small. The transition zone will
undergo marked enlargement in older men with
benign prostatic hyperplasia. A, Coronal section
at midprostate level. B, Sagittal midline section. C,
Parasagittal section. D, Axial section through
base. E, Axial section through apex.

9. • Supplied by prostatic branch of inferior vesical artery, a
branch of the internal iliac artery.
• Drained by prostatic venous plexus in communication
with the pudendal plexus to the deep dorsal vein (to the
internal iliac vein) with some communication to the
Batson vertebral venous plexus which offers a route for
the hematogenous spread of tumor in axial skeleton.
• Lymphatic drainage of the prostate goes to regional
pelvic lymph nodes (obturator and internal iliac nodes)
with channels to paraaortic and inguinal nodes.

10. Prostate Sectoral map

11. MR ANATOMY
• On TlWI, the prostate gland is uniform intermediate to
low signal similar to skeletal muscle.
• The high signal periprostatic fat defines the margin of the
prostate.
• Prostatic veins and neurovascular bundles are low signal.
• The peripheral zone is high in signal due to higher
water content and looser acinar structure.

12. • The central zone is lower in signal due to more
compact muscle fibers and acinar structure.
• The central and transitional zones become
heterogeneous with age and the development
of benign prostatic hyperplasia.
• The anterior fibromuscular stroma is low in
signal and has poorly defined margins.

13. Prostate anatomy. A, The prostate gland is composed of the central gland (CG),
which consists of the central zone and the transitional zone as well as the
peripheral zone (PZ) and anterior fibromuscular stroma (AFMS). B, The paired
seminal vesicles are perched posterolateral to the prostate gland. CZ, central
zone; PZ, peripheral zone.

14. Imaging Modalities
• USG and TRUS
• CT scan
• MRI
• MRS
• PET
• Radionuclide scan

15. MRI
• T1WI: gland is of intermediate signal intensity;
• T2W: peripheral zone- hyperintense,
central gland, anterior fibromuscular stroma, prostatic
capsule- low signal; Periprostatic venous plexus-high
signal.
• Seminal vesicles- convoluted, tubular structures,
posterior & superior to base; appear as grapes. On T2- low
signal walls with high signal contents.
• Neurovascular bundles- 5 & 7’ o clock as punctate signal
voids.
• More accurate in volume calculation

16. Normal zonal anatomy of the prostate gland. On TRUS the difference between a more echogenic
peripheral zone (P) and less echogenic transition zone (T) is well appreciated. The same
differentiation can be made on the endorectal MR T2-weighted images as the peripheral zone (P)
demonstrates a higher signal intensity than the transition zone (T). Small arrows = ejaculatory
ducts, long arrows = prostatic capsule, curved arrows =neurovascular bundles
P

17. Contd.
Compared with TRUS , MRI has following advantages
• Much larger field of view in order to identify adenopathy.
• Relatively operator independent reproducibility of imaging
plane and image quality on follow up studies
• Better tissue characterisation especially for complex lesions
such as post operative studies or bleeding adenomas
Advantage of TRUS :can be used for guided biopsy of
suspicious hypoechoic lesion and less expensive.

18. MR spectroscopy
• Noninvasive technique to determine molecular
metabolism within the body
• Metabolites are measured based on their slightly
difference magnetic frequencies or chemical shifts.
• In many pathological processes metabolic changes
precede anatomic changes during disease progression
• Early detection of new disease and therapeutic success
or failure.

19. Contd.
• Informations about physical and chemical properties of
the tissue sample are obtained in the form of spectrum
called MRS.
• MRI and MRS: based on same fundamental principle.
• MRI provides anatomic information as a visual image
whereas MRS obtains chemical information as a
spectrum or numerical values.

20. Cancer prostate at the peripheral zone with high Choline peak
and a low Citrate peak are evident.

21. Ca Vs benign on MRS
• In normal prostate and BPH increased level of
citrate & low choline is observed on proton MRS.
• In prostatic carcinoma, there is absent or
decreased citrate level and rise in choline.
• Tumor regression is similarly associated with fall
in choline levels.

22. Prostatic Specific Antigen (PSA)
• <1.5 ng/ml : Normal
• 2.0–3.9 ng/mL : High normal
• 4.0–10 ng/mL : Intermediate range
• 10 ng/mL : High range

23. PSA density
• PSA density = Total PSA/ prostate volume in cc^3), high
in cancer patients than normal.
• PSA density >= 0.15, proposed as the threshold for
biopsy in men with PSA levels of 4–10 ng/mL.
PSA Velocity
• It is the rate of PSA rise over time.
• In the 4 to 10–ng/mL PSA group, with three PSA
tests performed over 2 years & velocity exceeds 0.75
ng/mL/yr, this rapid change distinguishes men with
cancer from those with BPH with a specificity of 90%.
• Higher velocities are associated with increased cancer
aggressiveness.

24. MR Imaging Techniques
Anatomic T2-weighted MR Imaging;
• Work-horse of prostate MR imaging.
• High spatial resolution.
• Rapid acquisition with refocused echo sequences with a
small field of view, performed with endorectal and/or
external body phased-array coils.
• On T2-weighted images, prostate cancer can
appear as an area of low signal intensity within
the high signal intensity of a normal peripheral
zone.
• BPH itself is a round, well-defined, inhomogeneous area
with (variable) intermediate signal intensity and a low
signal- intensity rim that surrounds the expanded
transition zone.

25. MRI Zonal anatomy.

26. At level of midprostate to apex, a
low-signal-intensity lesion is
present on the right side of the
prostate, within the high signal
intensity of the peripheral zone
(outline), with signs of minimal
capsular invasion (arrow).
Prostatectomy prostate cancer,
corresponded to stage T3a
(extracapsular extension of 5 mm).
At midprostate level, a homogeneous low
signal intensity area in the ventral transition
zone is seen (outline), with loss of visibility of
healthy BPH structures (“charcoal sign”).
Invasion of anterior fibromuscular stroma
at the ventral prostate can be seen (arrows).
This lesion was suspicious for transition zone
cancer. At prostatectomy, stage T2c, Gleason
score 6 prostate cancer was found.

27. Limitation of T2-weighted imaging
• Focal areas of low signal intensity in the peripheral zone
do not always represent cancer.
• Benign abnormalities with low signal intensity:
 chronic prostatitis,
 Atrophy
 Scars
 Postirradiation or hormonal treatment effects
 Hyperplasia,
 Postbiopsy hemorrhage
• Low-signal-intensity lesions with a wedge shape
and a diffuse extension without mass may be
reliable signs of benignity.

28. Malignancy in Transitional Zone
Features are:
• Homogeneously low T2-weighted signal intensity.
• Ill-defined irregular edges of the suspicious lesion.
• Invasion into the urethra or the anterior
fibromuscular stroma.
• Lenticular shape.

29. Dynamic contrast enhanced MR Imaging
• Prostate is highly vascular organ.
• Pre and post gadolinium contrast images are not
sufficient for cancer detection.
• Resultant changes in vascular characteristics can be
studied well with dynamic contrast-enhanced MR
imaging.
• DEC MR imaging consists of a series of fast T1W
sequences covering entire prostate before & after
rapid injection (2–4 mL/sec) of a bolus of a
lowmolecular- weight gadolinium chelate such as
gadoterate meglumine or gadopentetate
dimeglumine.

30. • Assessment of signal intensity changes on T1W DEC MR
images to estimate contrast agent uptake in vivo can be
performed qualitatively, semiquantitatively or
quantitatively.
• Qualitative analysis of signal intensity changes can be
achieved by assessing the shape of the signal intensity–
time curve.
• Semiquantitative parameters {a)integral area under the
gadolinium-concentration–time curves, (b) wash-in
gradient (upward slope of First pass), maximum signal
intensity,(c) time-to-peak enhancement, and (d) start of
enhancement}.

31. DEC MR imaging of prostate cancer in 65Y/M
with PSA level of 8.3 ng/mL, clinical stage T2c cancer,
and Gleason score of 7 (3+4) in 80% of the volume of
systematic random biopsy specimens . (a, b) Axial DEC
T2-weighted MR images obtained at midprostate level,
with superimposed K trans (volume transfer constant)
parametric map on a and washout parametric map on
b. (a) Right peripheral zone (outline) shows contrast
enhancement (red) that is suspicious for prostate
cancer. (b) In addition to the transition zone (arrow),
right peripheral zone (outline) shows increased
washout. (c) Relative gadolinium concentration (y-
axis)-time (x-axis ) curve of tumor shows a type 3 curve
with fast increase, fast time to peak, and washout,
which are suspicious for cancer.

32. Diffusion Weighted Imaging(DWI)
• DWI is a fast, simple and readily available MR imaging
technique for prostate cancer.
• Nevertheless, DW imaging of the prostate has the
limitation of low in-plane spatial resolution, even at 3T.
• Healthy prostatic tissue has high ADC values whereas
prostatic cancer has low ADC values.
• Diffusion is restricted in prostatic cancer due to
destruction o f normal glandular structure and higher
cellular density than normal tissue.

33. DWI of prostate cancer. Axial ADC maps obtained at mid prostate
(a) Lesion with low ADC is suspicious for cancer in right peripheral zone
(arrows). This indicates intermediate to high cancer aggressiveness.
(b) Comma-shaped area with low ADC (mean ADC = 0.6 3 10 2 3 mm 2
/sec) is seen in ventral transition zone (arrows). This indicates
intermediate to high cancer aggressiveness.

34. Proton MRS Imaging
• The dominant peaks observed in these spectra are
from protons in citrate (approximately 2.60 ppm),
creatine (3.04 ppm) and choline compounds
(approximately 3.20 ppm).
• Polyamine signals (mostly from spermine) also may
be observed (approximately 3.15 ppm).
• Compared with healthy peripheral tissue or BPH
tissue, citrate signals are reduced and those of
choline compounds are often increased in
prostate cancer tissue

35. MR spectroscopic imaging in a 70-year-old man with a PSA level of 12
ng/mL and well-differentiated prostate cancer.
(a) Axial T2W turbo spin-echo MR Image shows stage T3a prostate cancer. Radical
prostatectomy revealeda solitary Gleason score 7 (3+4) adenocarcinoma with
extraprostatic extension. Red voxel placed in low-signal-intensity lesion in left
peripheral zone, which is suspicious for cancer; blue voxelhas been placed in benign-
appearing region in right peripheral zone.
(b) MR spectrum from red voxel-choline peak that is increased relative to citrate
peak. The choline plus creatine–to-citrate ratio, calculated from the integrals of the
spectral peaks from choline, creatine, and citrate, is 0.80, which is suspicious for
prostate cancer.
(c) MR spectrum from blue voxel -low choline peak and high citrate peak, consistent
with benign peripheral zone tissue. The choline plus creatine–to-citrate ratio is 0.32.

36. Multi-parametric MR imaging
• Minimal requirements for a multiparametric MR
imaging protocol include a combination of
T1- and T2-weighted MR imaging with
DW and dynamic contrast- enhanced MR
imaging.
• For detection and localization of lesions, the use
of a phased-array coil is sufficient;
• For staging indications, combination with an
endorectal coil may be preferred.

37. Multiparametric MR imaging for prostate cancer localization in the transition
zone in a 67-year old) (a)Axial T2-weighted turbo spin-echo image obtained at
the level of the base of the prostate shows area of lower signal in the right
ventral prostate (outline), which is suspicious for prostate cancer. Bulging is
present as a sign of stage T3 disease (arrows). (b) Axial MR image with
superimposed Kt rans parametric map (Mediodorsal part of the prostate
shows early enhancement (outline) but no increased K trans at low-signal-
intensity area in a. (c) On axial ADC obtained at same level as a, the right
ventral transition zone (outline) shows restriction , which suggests highly
aggressive cancer.

38. Multiparametric MR imaging of the prostate cancer (PSA level of 8.3 ng/mL, clinical stage T2c, Gleason score of 7
Views of multiplanar multiparametric images (A–E), quantitative information ( F) is also displayed. A–E show
tumor with bulging, suspicious for minimal stage T3A disease, in right peripheral zone at level of midprostate to
apex (arrow).
A , Axial K t rans mapfrom dynamic contrast-enhanced MR imaging projected over T2-weighted image .
B, Sagittal T2-weighted imawith color overlay showing washout (from dynamic contrast-enhanced MR imaging).
C, Axial ADC map D, Axial DW trace image ( b = 800 sec/mm 2 ). E, Axial T2-weighted image.
F, Relative gadolinium concentration–time curve (left) and MR spectrum (right) from chosen point of interest in
tumor (+). In MR spectrum, choline (chol) and citrate ( cit) peaks can be evaluated. The low-signal-intensity
lesion on E shows increased K t rans (on A ), restriction on C , high signal intensity on D , gadolinium
concentration–time curve type 3 and high choline peak on F.

39. Criteria for extracapsular invasion
• Periprostatic tumor stranding
• (asymmetric) low signal intensity in the seminal vesicles
• Asymmetry of the neurovascular bundle,
• Obliteration of the rectoprostatic angle,
• Irregular and local bulging of the prostatic contour (step-off or
angulation)
• Low signal intensity in the rectoprostatic fat
• Overt extracapsular cancer.

40. • Levator ani involvement- localized high SI on
T2WI
• Rectal inv- Demonstrated in 2 planes; disruption
of rectal wall.
• Invasion of bladder base
-T2WI : Interruption of the low intensity signal
of UB wall.

41. GLEASON SCORING SYSTEM
• The Gleason score determines the histological
grading of prostate cancer.
• A score of 1 to 5 is assigned to each of the two
largest areas of tumour involvement in the
samples obtained, based on the worst feature.(1:
least aggressive,5: most aggressive).
• These two scores are then added together to a
Gleason score of 1-10.
• This final score can then be grouped variably into
histopathologic grades which correlate with
progression free survival.

42.  2-4 (low grade):
• 100% progression free at 5 years
• 95.6% progression free at 10 years
 5-6:
• 96.9% progression free at 5 years
• 81.9% progression free at 10 years
 7:
• 76.9% progression free at 5 years
• 51.4% progression free at 10 years
 8-9:
• 59.1% progression free at 5 years
• 34.9% progression free at 10 years

43. STAGING

44. PIRADS – ASSESMENT
 PI-RADS (Prostate Imaging Reporting and Data System)
 The score is assessed on prostate MRI. Images are
obtained using a multi-parametric technique including
T2 weighted images, a dynamic contrast study (DCE)
and DWI. If DCE or DWI are insufficient for
interpretation the newest guidelines recommend
omitting them in the scoring.
 Currently, MR spectroscopy is not included in PI-
RADS scoring.
 A score is given according to each variable. The scale is
based on a score from 1 to 5 (which is given for each
lesion), with 1 being most probably benign and 5 being
highly suspicious of malignancy:

45. Scoring Scheme within PI-RADS Version 2 for Peripheral and Transition
Zone Abnormalities on the Basis of Their Appearance on ADC Maps and
High–b Value Diffusion-weighted MR Images

46. Scoring Scheme within PI-RADS Version 2 for Peripheral Zone Abnormalities
on the Basis of Their Appearance on T2-weighted MR Images

47. Scoring Scheme within PI-RADS Version 2 for Transition Zone Abnormalities
on the Basis of Their Appearance on T2-weighted MR Images

48. Flowchart showing the PI-RADS version 2 assessment categories.
DCE = dynamic contrast-enhanced MR imaging, T2-WI = T2-weighted
MR imaging.

49. Images of a 62 Y with prostate cancer (Gleason score, 4 + 4) detected
at systematic transrectal ultrasonography (US)–guided biopsy, who
was referred for multiparametric MR imaging staging (PIRADS- 5)
(a) Axial T2WI-a hypointense
focal lesion (black arrow) in
the right posterolateral and
anterior peripheral zone at
the midgland; the lesion has
an irregular or spiculated
margin (white arrows) and a
tumor-capsule interface of
more than 1 cm, findings
consistent with
extraprostatic extension (T2-
weighted imaging score: 5)
(b) & (c) ADC map and
computed high–b value
(1500 sec/mm2) diffusion-
weighted MR image (c)
show a 2.3-cm lesion that
is markedly hypointense
on the ADC map (arrows
on b) and markedly
hyperintense on the
diffusion-weighted MR
image (arrows on c) (DWI-
ADC score: 5).
(d) Axial dynamic contrast-
enhanced T1-weighted MR
image shows early
enhancement (or early phase
wash-in) of the lesion
(arrows) relative to the rest
of the gland,

50. Post-treatment appearances and
recurrent disease
• After radiation or hormonal therapy, the prostate
often becomes low signal on T2WI, an appearance
that should not be confused with tumour recurrence.
• The seminal vesicles can also become deformed and
show low-signal change but may retain small focal
areas of high-signal fluid.
• After a time, the peripheral zone of the prostate
may revert to its normal high signal on T2WI.

51. • Following treatment, a patient with prostatic carcinoma
is monitored for recurrent tumour by serial serum PSA
levels.
• Patients with rising levels normally have to be evaluated
with isotope bone scintigraphy, to identify disease in the
skeleton and MRI, to identify disease in the residual
prostate or prostatic bed, and lymph node enlargement
within the pelvis and retroperitoneum.
• The presence of an irregular new low-to-intermediate
signal intensity mass on the T2-weighted images is
highly suspicious of recurrent disease.

52. Conclusion
• To increase MR imaging accuracy for the different
clinical prostate cancer indications, one or more
functional MR imaging techniques should be
combined with T2-weighted MR imaging in a
multiparametric MR examination of the prostate.
• Suggested minimal requirements for a
multiparametric MR imaging protocol for clinical
evaluation of prostate cancer are T1- and T2-
weighted MR imaging in combination with DW and
dynamic contrast-enhanced MR imaging.

53. • T1-and T2-weighted MR imaging should be used
for evaluation of anatomy.
• Dynamic contrast-enhanced MR imaging can be
used for high-sensitivity identification of
potential prostate cancer locations (Little
standarisation).
• DW imaging or MR spectroscopic imaging are
accurate functional MR techniques, and they
may be added to improve specificity for different
clinical indications.

54. References
• CT and MRI of Whole Body- John Haaga.
• Prostate Cancer: Multiparametric MR Imaging for Detection,
Localization, and Staging Caroline M. A. Hoeks et al; Radiographics
2011.
• Characterization of Prostate Lesions as Benign or Malignant at
Multiparametric MR Imaging: Tiphaine Vaché et al;Radiographics
2014.
• PI-RADS Version 2: A Pictorial Update: Andrei S. Purysko, MD et
al; RadioGraphics 2016.

55. THANK YOU