Introduction
Methods
Section 1: clinical use of MRI
Multi-parametric MRI
Clinical use of MRI
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Low-risk: PSA <10 ng/mL, and biopsy Gleason score ≤6, and clinical stage T1–T2a
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Intermediate-risk: PSA 10–20 ng/mL, or biopsy Gleason score 7, or clinical stage T2b or T2c
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High-risk: PSA >20 ng/mL, or Gleason score 8–10, or clinical stage >T2c.
Treatment options: role of MRI
Life expectancy | Active surveillance | Radical surgery | Radiotherapy | Hormones | |
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Localised | 10–15 year estimated life expectancy (Generally these patients will be younger than 75) | Yes | Yes—consider nerve sparing | External or brachytherapy | No |
Localised | Less than 10–15 years | Yes | Rarely | External or brachytherapy | No |
Locally advanced | Any | No | No | In combination with hormones | Yes |
Metastatic | Any | No | No | Palliative | Yes |
A. Detection protocol |
Fast <30-min protocol without an endorectal coil (ERC). Images should cover entire prostate, and include T2WI, DWI and DCE-MRI. Imaging can adequately be performed at 1.5 T using a good 8- to 16-channel pelvic phased array (PPA). Anti-peristaltic drugs (Buscopan®, Glucagon®) should be given. |
• T2WI axial+sagittal: 4 mm at 1.5 T, 3 mm at 3 T; in plane resolution: 0.5 × 0.5 mm to 0.7 × 0.7 mm at both 1.5 T and 3 T. |
• DWI axial: 5 mm at 1.5 T, 4 mm at 3 T; in-plane resolution: 1.5 × 1.5 mm to 2.0 × 2.0 mm at 1.5 T and 1.0 × 1.0 mm to 1.5 × 1.5 mm at 3 T. ADC map should be calculated. At least 3 b-values should be acquired in three orthogonal directions and adapted to quality of SNR: 0, 100 and 800–1000 s/mm2. For calculation of ADC, the highest b-value that should be used is 1000 s/mm2. |
• DCE-MRI axial: 4 mm at 1.5 T and 3 T; in plane resolution: 1.0 × 1.0 mm at 1.5 T and 0.7 × 0.7 mm at 3 T. Quantitative or semi-quantitative DCE-MRI analysis does not have to be performed. Maximum temporal resolution should be 15 s following single dose of contrast agent with an injection rate of 3 mL/s. For DCE-MRI, imaging acquisition should be continued for 5 min to detect washout. Unenhanced T1WI images from this sequence can be used to detect post-biopsy haematomas. |
• MRSI: optionally, MRSI can be added to the detection protocol, but this requires an extra 10–15 min of examination time. For this ERC is mandatory at 1.5 T and optional at 3 T; volume of interest (VOI) aligned to axial T2WI; coverage of the whole prostate in the VOI; field of view at least 1.5 voxels larger than the VOI in all directions to avoid wrap-around or back folding; matrix of at least 8 x 8 x 8 phase-encoding steps with nominal voxel size <0.5 cc; spectral selective suppression of water and lipid signals; positioning of at least six fat saturation bands close to the prostatic margin (may be positioned inside the VOI) to conform to the prostatic shape as closely as possible; automatic or manual shimming up to a line width at half height of the water resonance peak between 15 and 20 Hz at 1.5 T and between 20 and 25 Hz at 3 T. |
B. Staging protocol |
45-min protocol for evaluating minimal extra-capsular extension. Preferably, this examination should be done with an ERC. Images should include entire prostate, with anti-peristaltic drugs. |
• T2WI axial, coronal and sagittal planes, 3 mm at 1.5 T and 3 T; in plane resolution: 0.3 × 0.3 mm to 0.7 × 0.7 mm at 1.5 T and 0.3 × 0.3 mm to 0.5 × 0.5 mm at 3 T. |
• DWI and DCE as detection protocol. |
• MRSI optional. |
C. Nodes and bone protocol |
30-min protocol, to assess nodal size and bone marrow metastases. Should be performed separately from A and B, as most patients do not require bone or node staging. |
• T1WI coronal of lower lumbar spine plus pelvis (SE or f/T SE) 3.0-mm slices |
• 3D f/T SE T2WI coronal of lower lumbar spine plus pelvis; 1.0-mm isometric voxels |
• DWI coronal of lower lumbar spine plus pelvis (b-values 0 and 600); slice thickness 3–4 mm, in plane resolution: 2.5–3.0 mm voxels |
• T1WI sagittal cervical and thoracic spine (SE or f/T SE) |
• STIR or DWI sagittal cervical and thoracic spine. |
MRI to determine tumour aggression
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PSA testing—every 3 months for 2 years, then every 6 months
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Regular DRE
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Repeat prostate TRUS-guided biopsies every 2–3 years.
Mp-MRI in men suspected to have prostate cancer with negative previous TRUS biopsy
Investigating men post-therapy with PSA rise
Section 2: MRI sequences for prostate gland evaluation
T2-weighted MR imaging
Caveats and conclusions
Dynamic contrast enhanced MRI
Caveats and conclusions
Diffusion weighted MRI
Caveats and conclusions
MR spectroscopic imaging
Caveats and conclusions
Section 3. MR equipment
MR coils
Imaging at 3 T
Section 4. Integration, reporting and communication of multi-parametric prostate MRI data
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PI-RADS score which relays the probability of cancer risk and its aggression, plotted on a scheme
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Location and, probability of extra-prostatic disease
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Pertinent incidental findings.
Scoring system for mp-MRI (PI-RADS)
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Score 1 = Clinically significant disease is highly unlikely to be present
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Score 2 = Clinically significant cancer is unlikely to be present
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Score 3 = Clinically significant cancer is equivocal
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Score 4 = Clinically significant cancer is likely to be present
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Score 5 = Clinically significant cancer is highly likely to be present.
Score | Criteria |
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A1. T2WI for the peripheral zone (PZ) | |
1 | Uniform high signal intensity (SI) |
2 | Linear, wedge shaped, or geographic areas of lower SI, usually not well demarcated |
3 | Intermediate appearances not in categories 1/2 or 4/5 |
4 | Discrete, homogeneous low signal focus/mass confined to the prostate |
5 | Discrete, homogeneous low signal intensity focus with extra-capsular extension/invasive behaviour or mass effect on the capsule (bulging), or broad (>1.5 cm) contact with the surface |
A2. T2WI for the transition zone (TZ) | |
1 | Heterogeneous TZ adenoma with well-defined margins: “organised chaos” |
2 | Areas of more homogeneous low SI, however well marginated, originating from the TZ/BPH |
3 | Intermediate appearances not in categories 1/2 or 4/5 |
4 | Areas of more homogeneous low SI, ill defined: “erased charcoal sign” |
5 | Same as 4, but involving the anterior fibromuscular stroma or the anterior horn of the PZ, usually lenticular or water-drop shaped. |
B. Diffusion weighted imaging (DWI) | |
1 | No reduction in ADC compared with normal glandular tissue. No increase in SI on any high b-value image (≥b800) |
2 | Diffuse, hyper SI on ≥b800 image with low ADC; no focal features, however, linear, triangular or geographical features are allowed |
3 | Intermediate appearances not in categories 1/2 or 4/5 |
4 | Focal area(s) of reduced ADC but iso-intense SI on high b-value images (≥b800) |
5 | Focal area/mass of hyper SI on the high b-value images (≥b800) with reduced ADC |
C. Dynamic contrast enhanced (DCE)-MRI | |
1 | Type 1 enhancement curve |
2 | Type 2 enhancement curve |
3 | Type 3 enhancement curve |
+1 | For focal enhancing lesion with curve type 2–3 |
+1 | For asymmetric lesion or lesion at an unusual place with curve type 2–3 |
D2. Qualitative magnetic resonance spectroscopic imaging (MRSI) | |
1 | Citrate peak height exceeds choline peak height >2 times |
2 | Citrate peak height exceeds choline peak height times >1, <2 times |
3 | Choline peak height equals citrate peak height |
4 | Choline peak height exceeds citrate peak height >1, <2 times |
5 | Choline peak height exceeds citrate peak height >2 times |
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>4 standard deviations from the mean normal value: 5 points
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>3–4 standard deviations from the mean normal value: 4 points
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>2–3 standard deviations from the mean normal value: 3 points
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>1–2 standard deviations from the mean normal value: 2 points
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≤1 standard deviation from the mean normal value: 1 point
Criteria | Findings | Score |
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Extra-capsular extension | Abutment | 1 |
Irregularity | 3 | |
Neurovascular bundle thickening | 4 | |
Bulge, loss of capsule | 4 | |
Measurable extra-capsular disease | 5 | |
Seminal vesicles | Expansion | 1 |
Low T2 signal | 2 | |
Filling in of angle | 3 | |
Enhancement and impeded diffusion | 4 | |
Distal sphincter | Adjacent tumour | 3 |
Effacement of low signal sphincter muscle | 3 | |
Abnormal enhancement extending into sphincter | 4 | |
Bladder neck | Adjacent tumour | 2 |
Loss of low T2 signal in bladder muscle | 3 | |
Abnormal enhancement extending into bladder neck | 4 |