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PI-RADS v2_1 recommended MR imaging protocols
| Imaging sequence | Technical parameters |
|---|---|
| Axial plane and a minimum of one additional | |
| T2 imaging | orthogonal plane (either sagittal or coronal) Straight axial plane to the patient or to the long axis of |
| the prostate | |
| FOV: 12-20 cm to image the entire prostate gland and | |
| seminal vesicles | |
| Section thickens/gap: 3 mm/0 mm | |
| In-plane resolution: ≤0.7 mm (phase) x ≤0.4 mm (frequency) | |
| DW imaging | Axial plane (same locations as for T2WI) |
| Free-breathing spin echo EPI sequence combined with spectral fat saturation is recommended | |
| Section thickness/gap: 3 mm/0 mm | |
| TE: ≤90 ms; TR: >3000 ms | |
| FOV: 16-22 cm | |
| In plane dimension: ≤2.5 mm phase and frequency | |
| ADC map calculation: low b-value should be set at 0 – 100 s/mm2, high b-value should be <1000 s/mm2 | |
| “High b-value”: b-value of ≥ 1400 sec/mm2; it can be acquired by scanning or calculated | |
| DCE | Axial plane (same locations as for T2WI) |
| Fat suppression and/or subtraction is recommended | |
| 2D or 3D T1 GRE sequence (preferred) | |
| Section thickness/gap: 3 mm/0 mm | |
| Injection rate: 2-3 ml/s | |
| TR/TE: <100 ms/ <5 ms | |
| In-plane dimension: ≤2mm X ≤2mm | |
| Temporal resolution: ≤15 s | |
| Total observation: >2min |
Summary of TNM guidelines for the staging of prostate cancer
| Category | Definition |
|---|---|
| Tumour | |
| Tx | Primary tumour cannot be assessed (e.g. CT study, severe artefacts on MRI) |
| T1a–T1b | Tumour incidental histologic finding |
| T1c | Tumour identified by needle biopsy but not visible by imaging |
| T2 | Organ confined disease |
| T2a | The tumour involves up to one half of 1 side of the prostate |
| T2b | The tumour involves more than one half of 1 side of the prostate |
| T2c | The tumour involves both sides of the prostate |
| T3 | Extraprostatic extension |
| T3a | Extraprostatic extension (unilateral or bilateral) or microscopic invasion of the bladder neck |
| T3b | Tumour invades seminal vesicle(s) |
| T4 | Tumour invades adjacent structures other than seminal vesicles, such as external sphincter, rectum, bladder, levator muscles, and/or pelvic wall |
| Node | |
| Nx | Regional lymph nodes were not assessed |
| N0 | No positive regional lymph nodes |
| N1 | Metastases in regional lymph node(s) |
| Metastasis | |
| Mx | M staging not assessed (e.g. MRI with pelvic only coverage) |
| M0 | No distant metastasis |
| M1 | Distant metastasis |
| M1a | Nonregional lymph node(s) |
| M1b | Bones |
| M1c | Other site(s) with or without bone disease |
PI-RADS v2 criteria for predicting extraprostatic extension
| Capsular abutment |
| Capsular irregularity, spiculation or retraction |
| Neurovascular bundle asymmetry or thickening |
| Obliteration of the rectoprostatic angle |
| Tumour-capsular contact > 10 mm |
| Bulge or loss of capsule |
| Measurable extracapsular disease |