1. No category

MR and Spectroscopy
for Prostate Cancer
Dr. P. De Visschere, Prof. Dr. G. Villeirs
Genitourinary Radiology and Mammography
University Hospital Gent
ESRU Uroradiology Course
29/10/2010
MR and Spectroscopy
for Prostate Cancer
1) How is MRI of the prostate performed?
2) Can we see the prostate with MRI?
3) Can we detect prostate cancer with MRI?
4) Are there indications for MRI and Spectroscopy in
prostate cancer?
1) How is MRI of the
prostate performed?
MRI of the Prostate
• 1.5T or 3.0T
• Endorectal coil + pelvic phased-array coil
– In some indications possible with only body coil
• Avoid motion artifacts:
– Tight band around pelvis (PPA coil)
– Scopolamine (Buscopan) IV
MRI of the Prostate
Endorectal Coil
60 cc
MRI of the Prostate
• Imaging Sequences
– Morphologic Imaging:
• 4mm ax/sag/cor fast-T2 weighted sequence
• 4mm ax GE or SE T1 weighted sequence
– Functional Imaging:
• 4mm Diffusion Weighted Imaging (DWI)
• Dynamic Contrast Enhanced Imaging
(DCE-MRI)
• MR Spectroscopic Imaging (MRSI)
Contra-Indications MRI:
Ferromagnetic devices
Pacemaker, neurostimulator, hearing device,
dental prosthesis, metallic splinter in the
eye, …
http://www.mrisafety.com/list_search.asp
Claustrophobia
Noise 60-90dB
20 minutes
2) Can we see the
prostate with MRI?
Can we see the prostate with MRI?
T2-Weighted Images
T Two Water White
Morphologic Imaging of the Prostate
T2 Weighted Sequences
• Excellent depiction of prostatic zonal anatomy
• Assessment of prostate volume
– PSA density (absolute PSA value / prostate volume)
– Central gland enlargement : BPH
• Detection and staging prostate carcinoma
• DD Prostatitis, hormonal changes, fibrosis
Morphologic T2-Weighted Images
Prostate Zonal Anatomy
Periurethral Glands +
Transition Zone +
Central Zone =
CENTRAL GLAND
MR
Morphologic T2-Weighted Images
Prostate Zonal Anatomy
Periurethral Glands +
Transition Zone +
Central Zone =
CENTRAL GLAND
MR
Morphologic T2-Weighted Images
Prostate Zonal Anatomy
Periurethral Glands +
Transition Zone +
Central Zone =
CENTRAL GLAND
MR
Morphologic T2-Weighted Images
Prostate Zonal Anatomy
Periurethral Glands +
Transition Zone +
Central Zone =
CENTRAL GLAND
MR
Morphologic T2-Weighted Images
Prostate Zonal Anatomy
Peripheral Zone
MR
Morphologic T2-Weighted Images
Prostate Zonal Anatomy
Anterior
Fibromuscular
Stroma
MR
Morphologic T2-Weighted Images
Prostate Zonal Anatomy
Prostatic Apex
Transverse T2
Midprostate
Seminal Vesicles
Morphologic T2-Weighted Images
Urethra
External
Sphincter
Urethra
Urethra
Sagittal
Coronal
Transverse
Morphologic T2-Weighted Images
Deferent Ducts
Transverse
Coronal
Morphologic T2-Weighted Images
Benign Prostatic Hyperplasia
CG
CG
CG
PZ
BPH on T2-weighted imaging:
- Central gland heterogeneous nodular enlargement
- Thinning of peripheral zone
- Bladder wall thickening and diverticula
PZ
Morphologic T2-Weighted Images
BPH
MRI is not indicated for diagnosis of BPH
- Usually incidental finding in patient with elevated PSA
- PSA density will be normal: PSA / prostate volume
Morphologic T2-Weighted Images
BPH after therapy (TURP)
3) Can we detect prostate
cancer with MRI?
Morphologic T2-Weighted Images
Prostate Cancer
Prostate cancer:
- Low signal intensity relative to normal peripheral zone
- >70% in peripheral zone
- Prostate usually not enlarged
Morphologic T2-Weighted Images
Prostate Cancer
Peripheral Zone Tumor
with Body Coil
Transverse T2
Peripheral Zone Tumor
with Endorectal Coil
Morphologic T2-Weighted Images
Prostate Cancer local staging
Gross capsular penetration:
Seminal vesicle invasion
-irregular capsular bulge
-infiltration of periprostatic fat
-neurovascular bundle asymmetry
-low SI in lumen SV
-focal thickening SV wall
T3a
T3b
Morphologic T2-Weighted Images
Prostate Cancer detection
• Diagnostic accuracy detection prostate carcinoma
– body coil: 50-60%, endorectal coil 60-70%
• Obscured tumors (sensitivity):
– Prostate cancer in central gland
– Mucinous prostate cancer
– Low signal intensity lesion in
peripheral gland (specificity):
– DD prostatitis, post-biopsy
hemorrhage, post-treatment
(hormonal, radiotherapy)
changes, fibrosis
T
Morphologic T2-Weighted Images
Prostate Cancer detection
DD Prostatitis:
- Diffuse or triangular shaped low SI areas in PZ
- Often incidental finding, can simulate PrCa
- Endorectal coil painfull in acute prostatitis
Morphologic T2-Weighted Images
Prostate Cancer detection
T2
T1
DD post-biopsy hemorrage:
- Low SI areas on T2-WI
- Hemorrage has high SI on T1-WI
- The normal prostate has a homogenous isosignal
similar to that of the adjacent muscles on T1-WI
T1
Morphologic T2-Weighted Images
Prostate Cancer detection
• Morphologic T2-weighted images:
– Diagnostic accuracy detection prostate
carcinoma 50-70% = not bad, but
• Additional functional imaging
recommended:
– Diffusion Weighted Imaging, Dynamic
Contrast Enhanced MR, Spectroscopy
MRI of the Prostate
• Imaging Sequences
– Morphologic Imaging:
• 4mm ax/sag/cor fast-T2 weighted sequence
• 4mm ax GE or SE T1 weighted sequence
– Functional Imaging:
• 4mm Diffusion Weighted Imaging (DWI)
• Dynamic Contrast Enhanced Imaging
(DCE-MRI)
• MR Spectroscopic Imaging (MRSI)
Functional Imaging of the Prostate
Diffusion weighted imaging
• Visualize the amount of random (‘Brownian’)
movements of water molecules (diffusion)
– Dependent on:
• binding to macromolecules
• tissue density (hydrophobic cell membranes)
• cell organisation and microstructures
• Diffusion weighted images:
– 4mm single shot FS echo-planar imaging (EPI) DWI
sequence (anisotropic)
– Image acquisition at various b-values
• b=0, 250, 500, 750 and 1000 s/mm²
• Apparent Diffusion Coefficient (ADC)
Functional Imaging of the Prostate
Diffusion weighted imaging
• Prostate cancer: decreased diffusion
– Replacement of normal glandular tissue by
hypercellular tumor
• ADC value ~ Gleason grade
ADC
Functional Imaging of the Prostate
Diffusion weighted imaging
• Increased prostate cancer detection: ?
– Too early for firm conclusions
T2
DWI
ADC
Functional Imaging of the Prostate
Diffusion weighted imaging
• Increased prostate cancer detection: ?
– Too early for firm conclusions
T2
DWI
ADC
MRI of the Prostate
• Imaging Sequences
– Morphologic Imaging:
• 4mm ax/sag/cor fast-T2 weighted sequence
• 4mm ax GE or SE T1 weighted sequence
– Functional Imaging:
• 4mm Diffusion Weighted Imaging (DWI)
• Dynamic Contrast Enhanced Imaging
(DCE-MRI)
• MR Spectroscopic Imaging (MRSI)
Functional Imaging of the Prostate
Dynamic Contrast Enhanced MRI
• Intravenous bolus injection of Gadolinium
• Dynamic Scan sequences
– T1-weighted images
– 10 slices of 3mm, acquired every <10sec
• Assessment of tumor neovascularisation
Dynamic Contrast Enhancement Evaluation
Principles of enhancement
Invasive lesion
Enhancement
Angiogenetic factors
Growth of existing capillaries
De novo angiogenesis
Increased in- and efflux
Increased extracellular space
Abnormal configuration: AVshunts and defective endothelium
Increased extravasation
180
160
140
120
100
80
60
40
20
0
1
2
3
4
5
6
Functional Imaging of the Prostate
Dynamic Contrast Enhanced MRI
• Most prostate carcinoma:
– Earlier and higher peak enhancement with steep slope of the
SI-time curve as well as early washout of signal.
– increased vascular permeability and interstitial fluid volume
*G. Jager, J. Barentsz, Nijmegen Group
Functional Imaging of the Prostate
Dynamic Contrast Enhanced MRI
• Diagnostic accuracy dCE MRI: 70 - 90 %
• Useful in detection recurrence after
radical prostatectomy or radiation therapy
MRI of the Prostate
• Imaging Sequences
– Morphologic Imaging:
• 4mm ax/sag/cor fast-T2 weighted sequence
• 4mm ax GE or SE T1 weighted sequence
– Functional Imaging:
• 4mm Diffusion Weighted Imaging (DWI)
• Dynamic Contrast Enhanced Imaging
(DCE-MRI)
• MR Spectroscopic Imaging (MRSI)
Functional Imaging of the Prostate
MR Spectroscopy
• Evaluation of prostatic metabolism
• Voxels of each 6 mm³
Functional Imaging of the Prostate
MR Spectroscopy
H20
fat
• In MRI we disturb spin motion of the protons in the
magnetic field and record their resonance signals
Functional Imaging of the Prostate
MR Spectroscopy
H20
fat
• The resonance signals for water, fat, cellular
metabolites, … occur at distinct frequencies in the
spectrum
Functional Imaging of the Prostate
MR Spectroscopy
H20
fat
• The amplitude of the signal and the areas under these
curves are related to the concentration of the
respective metabolites.
Functional Imaging of the Prostate
MR Spectroscopy
H20
fat
• Spectroscopy: signals of fat and water are suppressed
• Citrate, choline, creatine
Functional Imaging of the Prostate
MR Spectroscopy
Normal Prostate
Dominant citrate peak,
low chol/creat
Unique metabolism of healthy prostate: synthesizing and secreting large amounts of citrate
Functional Imaging of the Prostate
MR Spectroscopy
Prostate Cancer
Reduced citrate,
elevated chol/creat
Prostate cancer: krebs cycle activation citrate reduction, cellmembranes choline elevated
MR-Spectroscopy
(Chol+Creat)/Citrate Ratio Images
Chol + Creat
Citrate
Mebatolite Index
MR-Spectroscopy
(Chol+Creat)/Citrate Ratio Images
Ratio in
Normal Prostate: ↓ ↓
Ratio in high grade
Prostate Cancer: ↑ ↑
MR-Spectroscopy
(Chol+Creat)/Citrate Ratio Images
Ratio in low-grade
tumor and BPH ≈ 1
Ratio in intermediate
grade tumor ↑
MR Spectroscopy has the potential for non-invasive
assessment of PrCa aggressiveness (vs Gleason score)
MR-Spectroscopy
(Chol+Creat)/Citrate Ratio Images
- Target biopsy
- Focus radiation therapy
Ratio in
Normal Prostate ↓
Ratio in
Prostate Cancer ↑
• Villeirs et al, EJR nov 2009:
– MRI + MRSI: Sensitivity PrCa Gleason 4+3 or higher: 92,7%
rebiopsy if previous negative biopsy
– MRI + MRSI: Negative Predictive Value for PrCa Gleason 4+3 or
higher: 98,4%
active surveillance : it will be a lower grade PrCa
no rebiopsy in elevated PSA with multiple previous negative biopsy
• Diagnostic Accurracy Spectroscopy: 70-90%
4) Are there indications for
MRI and Spectroscopy in
prostate cancer?
Management of Prostate Cancer:
can MRI help you?
• The most common tumor in Western countries.
– But up to 40% of PrCa will never become symptomatic
• Identification of “clinically significant disease”
– Patient age and comorbidity, PSA value, Histological Gleason
Grading and TNM staging.
• Therapy
– Radical prostatectomy
• If T1 or T2 disease (no invasion of capsula or seminal vesicles)
– Radiotherapy / chemotherapy / hormonal therapy / …
– Active surveillance ~ watchful waiting
• PSA < 10 ng/ml, Gleason <6, TNM <T2a, MRI/MRS –
Management of Prostate Cancer:
can MRI help you?
• Tumor Detection
– Presence of a tumor, vascularisation, metabolism,
determination of aggressiveness
• Tumor Staging (TNM)
– Local: size of lesion, number of lesions, localisation
– ‘Distant’
• Pelvic lymph nodes (N1)
• Pelvic bone metastases (M1)
• NB: distant lymph nodes, distant bone metastasis, visceral metastases (lung, liver):
diagnostic lymphadenectomy, CT
Indications MRI in Prostate Cancer
• Tumor Detection
– Persistent PSA elevation but normal biopsies:
• Are there high grade tumors on MRI+MRSI?
– if so, then targeted rebiopsy
– MR-guided biopsy
– Histologically proven low grade PrCa, candidate for
active surveillance:
• Are there high grade tumors on MRI+MRSI?
– if so, then no active surveillance
– Radiotherapy planning for known Prostate Cancer
• Focus center
• MRI without endorectal coil – to correlate with CT
Indications MRI in Prostate Cancer
• Tumor Staging (TNM)
– Local: histologically proven PrCa, clinically T1 or T2
• Capsular or seminal vesicle invasion?
To conclude…
MRI for Prostate Cancer
Morphologic (T2-WI) sequences,
preferably with functional imaging
techniques (DWI, Spectroscopy or
DCE-MRI)
To conclude…
MRI for Prostate Cancer
DCE-MRI and DWI increase
sensitivity and may predict tumor
aggressiveness
To conclude…
MRI for Prostate Cancer
MR+Spectroscopy is able to detect or
exclude high grade prostate cancer
To conclude…
MR and Spectroscopy for Prostate Cancer
• PrCa Detection:
– Persistent PSA elevation but previous negative biopsies
• High grade tumor on MR+MRSI? If so, then targeted rebiopsy
– Biopsy-proven low grade prostate cancer, candidate for
active surveillance
• High grade tumor on MR+MRSI? If so, then no active surveillance
– Radiotherapy planning
• PrCa Staging:
– Biopsy-proven prostate cancer, clinically T1 or T2
• Capsular or seminal vesicle invasion? If so, then no surgery
To conclude…
MR and Spectroscopy for Prostate Cancer
MRI will undoubtly play an increasing
role in detection and staging of prostate
cancer
– MR is available in nearly every hospital
– But radiologists need to be teached…
MR and Spectroscopy for
Prostate Cancer
[email protected]
P. De Visschere, G. Villeirs
Genitourinary Radiology,
Ghent University Hospital, Belgium.