Multiparametric MRI (mpMRI) of the prostate combines anatomic information from T1-weighted and T2-weighted sequences with functional information from diffusion-weighted imaging (DWI) and dynamic contrast enhancement (DCE). In some situations other techniques like MR spectroscopy (MRS) may also be employed.
The detection and localization of clinically significant prostate cancer in patients with negative biopsy or without a previous biopsy is a major goal of multiparametric MRI (mpMRI) 1-3.
Clinically significant prostate cancer has been defined on histology as Gleason score ≥7 (including 3+4 with prominent but not predominant Gleason 4 component), and/or volume ≥0.5 mL, and/or extraprostatic extension (EPE) 2.
Interpretation and reporting of mpMRI should be done following standardized scoring systems, such as Prostate Imaging-Reporting and Data System (PI-RADS v2.1) 2.
In order to improve the accuracy and reproducibility of multiparametric MRI some clinical considerations (timing of MRI after biopsy, patient preparation, and information), as well as technical specifications with respect to magnetic field strength, choice of the coil (endorectal vs pelvic), and more importantly sequence parameters and orientation, have to be fulfilled 2.
T2 weighted images are used in the evaluation of the prostatic anatomy, in particular for the assessment of the transition zone (TZ).
They also depict abnormalities in the peripheral zone (PZ), central zone (CZ) and anterior fibromuscular stroma (AFMS) of the gland, and to assess extraprostatic extension (EPE) and seminal vesicle invasion (SVI).
Diffusion-weighted imaging (DWI)
Diffusion-weighted imaging reflects the random motion of water molecules and adds a key functional component to multiparametric MRI.
With regards to PI-RADS, DWI is used as the primary evaluation of the peripheral zone (PZ) of the prostate gland but can also upgrade a focal lesion of the transition zone if they differ from the predominant background appearance.
They can also help to differentiate seminal vesicle invasion from bleeding.
Contrast-enhanced (DCE) MRI
Dynamic contrast-enhanced MRI adds another functional component to multiparametric MRI (mpMRI).
It serves as a secondary component in PI-RADS (v2.1), upgrading a PI-RADS 3 lesion to PI-RADS 4 assessment category if there is early enhancement.
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- 2. American College of Radiology. Prostate Imaging – Reporting and Data System. 2019. Version 2.1.
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