Prostate MRI
Dr. A. Stockman
Indications
• Tumour detection or exclusion in patients with clinical suspicion of prostate cancer – Elevated PSA > 4.0 ng/mL – Rising PSA – Suspicious digital rectal exam (DRE) – Negative biopsy but continuous clinical suspicion of prostate cancer
• Staging of patients with known prostate cancer – Curative intent – Active surveillance
Benefits Prostate MRI
• Noninvasive imaging technique
• No ionizing radiation
• Early detection
• Localisation
• Risk stratification
• Extent of prostate cancer / staging
Zonal anatomy
• Base 6 sectors on each side: – AS: anterior fibromuscular stroma – TZ: anterior and posterior transition zone – PZ: anterior and posterior zone – CZ: central zone around the ejaculatory ducts
• Midportion 6 sectors on each side: – AS: anterior fibromuscular stroma – TZ: anterior and posterior transition zone – PZ: anterior, posteromedial and posterolateral peripheral zone
• Apex 6 sectors on each side: – AS: anterior fibromuscular stroma – TZ: anterior and posterior transition zone – PZ: anterior, posteromedial and posterolateral peripheral zone
• Seminal vesicles
Prostate cancer risk– zonal anatomy
• Peripheral zone (PZ): 70-75%
• Transition zone (TZ): 25%
• Central zone (CZ):
PI-RADS v2
• Prostate Imaging Reporting and Data System • Standardized acquisition, interpretation and reporting of prostate
MRI. • Multiparametric MRI • T2-weighted (T2W) • Diffusion weighted imaging (DWI) • Apparent diffusion coefficient (ADC) • Dynamic contrast-enhanced imaging (DCE)
PI-RADS v2
• PI-RADS 1: very low (clinically significant cancer is highly unlikely to be present)
• PI-RADS 2: low (clinically significant cancer is unlikely to be present)
• PI-RADS 3: intermediate (the presence of clinically significant cancer is equivocal)
• PI-RADS 4: high (clinically significant cancer is likely to be present)
• PI-RADS 5: very high (clinically significant cancer is highly likely to be present)
Results
The PIRADS score provides an effective framework for determining the likelihood of prostate cancer on MRI.
• PPV* of PI-RADS 3: 10.6% • PPV* of PI-RADS 4: 44% • PPV* of PI-RADS 5: 100% * positive predictive values
E. NiMhurchu, et al. Predictive value of PI-RADS classification in MRI-directed transrectal ultrasound guided prostate biopsy. Clinical Radiology. 2016; Volume 71, Issue 4, Pages 375–380.
US/MRI fusion
•Targets identified in MRI/PI-RADs report
• Importing a PI-RADS report
•PI-RAD Sector of Interest aligned
with live B-Mode Image
FusionVu using a PI-RADS Report
US/MRI fusion
•Targets identified in MRI/PI-RADs report
• Importing annotated MR images
•Annotated MR images aligned
with live micro-ultrasound image
FusionVu using a MRI