Sequence | Rationale/investigated parameter | Technique | Role in prostate cancer assessment with mpMRI | Limitations |
---|---|---|---|---|
DWI | To exploit restricted diffusion of water molecules as a marker of increased cellularity and neoplastic reorganisation of normal glandular tissue | • Fat-saturated, free-breathing single-shot spin-echo echo-planar imaging • At least two b values to generate the ADC map (e.g., minimum 50–100 s/mm2, maximum 800–1000 s/mm2); extrapolated ultra-high b-values (≥ 1400 s/mm2) can also be used to generate the ADC map • Ultra-high b values can be acquired to increase tumour conspicuity (not for the ADC map generation in less performing systems) • Field of view 16–22 cm, slice thickness ≤ 4 mm without gap, pixel size ≤ 2.5 mm (phase and frequency), TR ≤ 3000 ms, TE ≤ 90 ms | Detection and localisation: • dominant sequence for assessing PZ findings • secondary role in assessing category 3 findings found by T2WI in the TZ | • Sensitive to artefacts from air in the rectum and/or motion • Distortions • Relatively unstandardised technique, leading to limited reproducibility of the quantitative analysis of ADC (no definite cut-off values) • Significant overlap of ADC values between benign conditions and tumours with different aggressiveness |
T2WI | To provide high-resolution and high-contrast representation of the zonal anatomy of the prostate, as well as of periprostatic anatomy (seminal vesicles, neurovascular bundles, bladder, rectum, and the levator ani) | • 2D turbo spin-echo with high spatial resolution: field of view 12–20 cm to cover the prostate and the seminal vesicles; slice thickness ≤ 3 mm with no gap; pixel size ≤ 0.7 mm (phase) x ≤ 0.4 mm (frequency) • Sagittal, oblique transverse, oblique coronal (posterior prostate wall as anatomic landmark) | • Detection and localisation: dominant sequence for assessing TZ findings • Locoregional staging: detection of extraprostatic extension or seminal vesicle invasion | • Nonspecific tumour appearance, overlapping with that of non-malignant conditions (e.g., inflammation or post-biopsy changes) • Sensitive to motion artefacts given the prolonged acquisition time |
DCE | To detect earlier and more intense contrast enhancement of cancer compared to normal prostatic tissue, as the expression of tumoural neoangiogenesis (denser, poorly formed vessels with increased capillary permeability) | • Sequential acquisition of a T1-weighted 2D or 3D gradient-echo sequence with high temporal resolution (≤ 10 s, ideally ≤ 7 s, with TR < 5 ms and TE < 100 ms). Acquisition before, during and after contrast injection (at least 2 min) to detect early enhancement • Field of view encompassing the whole gland and seminal vesicles • Slice thickness ≤ 3 mm without gap, and pixel size ≤ 2 mm (phase and frequency) • If possible fat-saturated or subtracted images • Oblique transverse plane • Contrast injection rate 2–3 mL/s | • To upgrade ambiguous findings in the PZ • See Table 3 for further details | • Variable enhancement pattern of cancer, overlapping with non-malignant conditions (e.g., inflammation or benign prostatic hyperplasia) • Longer acquisition time (> 2 min) to assess the permeability |