2. 1. Introduction on MRI T1 & T2
2. Prostate Anatomy MRI
3. PIRADS Prostate sector map
4. Introduction on DWI ,ADC and DCE
5. MR spectroscopy
6. MRI guided biopsy
7. Clinically Significant Prostate Cancer
8. PIRADS
CONTENTS
3. MRI interpretation T1 v T2 images Key points
• On T1 images FAT is white(bright), fluid dark
• On T2 images both FAT and WATER are white(bright)
• The two basic types of MRI images are T1-weighted and T2-weighted
images, often referred to as T1 and T2 images.
• White – Hyperintense
• Black - Hypointense
5. 5
T1 Weighted Image
• Better delineation of anatomy
• Normal prostate- homogenous intermediate to
Low signal intensity
• Better for characterising infiltration of disease
processes into adjacent fat plane
• However- insufficient soft tissue contrast
Resolution for visualizing intraprostatic anatomy
6. Normal MRI appearance of prostate
•Homogenous low signal intensity on T1W
•Zonal anatomy- best in T2
•Normal peripheral zone- high signal intensity
•Signal intensities in CZ and TZ lower
•AFS – low signal intensity
7.
8.
9.
10. •Hypo intense lesions(CaP vs hemorrhage) on T2-
weighted images
•T1-weighted sequences are obtained before T2 –
hemorrhage- bright lesions on T1 whereas tumour will
remain dark
•If hemorrhage +, leads to false positives on T2-
weighted sequences, DWI/ADC, and DCE images.
16. PIRADS 2.0 Vs 2.1
Revisions in the Sector Map
Two additional sectors
added for the Right And
Left Posterior medial
PZ(PZpm) at the base.
Now 41 sectors total(38
prostae, 2SV , 1
membranous urethra
17. MRI in prostate cancer
• Most accurate non invasive method for staging, local extent of prostate
cancer
• Definitive test for determining treatment options
(surgery Vs RT)
• MR guided biopsy
• Development of endorectal coil- increased accuracy to 82%
18. T2WI
• Workhouse of prostate MRI
• High spatial resolution and defines zonal anatomy
• PZ- High signal intensity on T2WI, cancer- low signal
• Low signal- also seen in prostatitis, fibrosis, scar tissue, post biopsy
hemorrhage or post irradiation.
• Potential of MRI has improved by combining anatomical and
functional imaging methods, known as mpMRI
19. Cancer in transitional zone- T2WI
• ‘Erased charcoal’ appearance
• Indistinct margins of nodule
• Extension of low signal into PZ
• Lenticular shape
20. Extracapsular extension in MRI prostate
• Irregular bulging of prostatic outline
• Breach of capsule with extracapsular spread
• Asymmetry of neurovascular bundle
21.
22. Prostate MRI usually is referred to as an
mpMRI
which consists of
1. Anatomic
2. Functional imaging techniques.
• Anatomic imaging should include T1- and T2-weighted
images.
• Functional imaging includes DWI with ADC maps, DCE
sequences.
• Combination of T2, DCE, DWI has yielded NPV & PPV >
90%.
23.
24. Diffusion Weighted Imaging
• DWI assesses diffusion of water molecules (Brownian
motion) within magnetic field.
• If water moves, it loses signal(appears dark)
• If water stays, retains signal (white)
• Higher density of cells in a tissue limited motion of
water(restricted diffusion) high signal intensity on DWIs
25. b Value
• It is a factor that reflects strength & timing of gradients used
to generate DWI
• A filter to remove less intense light and allow only bright
spots to be seen
• b-value of >2000 – malignancy
26. Apparent diffusion coefficient (ADC) -
Measure of magnitude of diffusion (of water molecules) within tissue,
and is calculated using MRI with DWI
• Quantitative assessment of the DWI.
• ADC- mirror image of DWI (exactly opposite of DWI)
• ADC used to crosscheck DWI finding and confirm
• Cancer – bright on DWI and hypointense on ADC(just like T2W)
27.
28. 29
Dynamic Contrast Enhanced MRI
• DCE-MRI is based on repetitive acquisition of sequential
images during the passage of a contrast agent within a
tissue of interest
• Based on tumor angiogenesis
• Malignancy - Rapid wash in and rapid wash out
• DCE-MRI enables the visualization of lesion
vasculature and permeability
• plays a role in tumor detection and therapy monitoring
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30.
31.
32. MR Spectroscopy
• May be useful for assessing malignancy risk
• Not included in PIRADS scoring
• Parameters used- Choline, creatine and citrate
• In malignancy, citrate decreases and creatine and choline increases.
• The higher the choline/citrate ratio, the greater the aggressiveness of
the cancer.
33.
34. PIRADS is an accurate tool in the detection of clinically
significant prostate cancer.
Definition of clinically significant cancer as diagnosed on HPE
is:
1. Gleason score > 7
2. Tumor volume > 0.5cc and/or
3. Extra prostatic extension (EPE).
TZ- best assessed by T2WI
PZ- best assessed by DWI
46. mpMRI when used with PSA followed by targeted biopsy of MRI visible
lesions- better alternative to systenativ TRUS biopsy in diagnosis of prostate
cancer
47. Clinical application of mpMRI
• Can potentially reduce
Unnecessary biopsies
Number of biopsy cores
• Avoid false negative results of DRE,PSA and TRUS guided
biopsy
48. mpMRI usage in prostate biopsy
• MRI guided biopsy techniques:
Cognitive fusion biopsy:
Operator identifies lesion and targets it to TRUS. A primary
disadvantage is inability to record and confirm biopsy needle placement
Image guided targeted prostate biopsy
In bore MRI guided biopsy
49. In bore MRI guided biopsy:
Performed when patient is in MRI unit, Expensive, needs
specialised equipment
MRI/TRUS fusion biopsy
Software guided fusion
50.
51. Take home points
• mpMRI- T2WI, DWI with ADC, DCE
• TZ- Best assessed with T2WI
• PZ- Best assessed with DWI
• Sectors- 39 in PIRADS 2.0
• Type 3 curve- in DCE- s/o prostate cancer
Citrate- normally found in prostatr, choline- present bound to cell membrane.Malignancy- bcoz of increased cell turnover- breakdown products of cell membrane- choline increased. Malignant cells- reduced synthesis of citrate
