Suspected prostate cancer — detection before biopsy

PI-RADS v2.1; NICE NG131; ACR AC prostate detection and staging

MRI comes before biopsy, not after it. Doing it first lets a proportion of men avoid biopsy altogether and directs the needle in those who still need one; doing it after leaves post-biopsy haemorrhage obscuring the peripheral zone for weeks.

Raised or rising PSA, abnormal digital rectal examination, or a prior negative biopsy with persistent suspicion — in a man who has not yet been biopsied for this episode.

Referenced decision support — confirm against your local protocol.

Decision support, not a directive. Protocols and timings shown are typical published ones — your local protocol takes precedence, and the vetting radiologist decides.

The request in front of you

Everything is optional. Leave a field alone and the answer assumes nothing — the verdict updates as you go.

Study requested

What the referrer actually asked for. It is evidence of intent, not a constraint on the right answer.

Contrast as written

What the request form says, not what it should say.

Age

Pick a band, or type an exact age if it matters.

years

Pregnancy status

Renal risk factors

The question a vetter can actually answer from the request. An explicit “none known” is a real answer, and it removes checks rather than deferring them.

Previous contrast reaction

The pathway — tap anything already done

Marking a study complete moves the answer on. A patient arrives partway through a pathway far more often than at the start of one.

Accept as requested

MRI Prostate — multiparametric (PI-RADS)

MRI Prostate

What we'd amend, and why

Each sequence answers a different question, which is why the protocol is multiparametric rather than long. High-resolution T2 provides the anatomy and is the dominant sequence in the transition zone, where cancer must be separated from nodular hyperplasia. Diffusion is the dominant sequence in the peripheral zone, where dense tumour cellularity restricts water motion and produces the low ADC that carries most of the diagnostic signal. The dynamic series adds focal early enhancement, whose defined role is to resolve equivocal peripheral zone findings. Acquired before biopsy, the study is clean of haemorrhage and can direct a targeted needle rather than merely confirm a systematic one.

Nothing needs resolving before this goes ahead. Routine checks below are owned downstream.

How was this decided?

pathwaystandard — Adults — pre-biopsy detection
rulerule-mr-device-screening — MR safety screening for implants and foreign bodies; checked by Radiographer at the scanner
rulerule-contrast-reaction-premed — Prior contrast reaction and elective premedication; checked by Nurse before the scan
rulerule-gadolinium-renal — Kidney function and gadolinium-based contrast; checked by Radiographer at the scanner
rulerule-pregnancy-gadolinium — Gadolinium in known or possible pregnancy; checked by Radiographer at the scanner
rulerule-iv-access — Intravenous access adequate for the planned injection; checked by Radiographer at the scanner

Decision support only. Local protocol takes precedence.

Handled at the scanner(2)nothing for you to do

Settled and owned downstream. Each returns to a radiologist only on the stated trigger.

MR safety screening for implants and foreign bodies
Complete the MR safety questionnaire, verify implant labelling and its stated conditions of use against this scanner and this protocol, and ensure no ferromagnetic object enters Zone IV.
Radiographer at the scannerBefore the scan
Flags back if: An implant or retained foreign body that is MR Unsafe, unlabelled, or cannot be identified; or an MR Conditional device whose stated conditions this scanner or the requested protocol cannot satisfy; or a credible unexcluded intraocular metallic foreign body history.
Intravenous access adequate for the planned injection
Site and test a cannula that supports the protocol flow rate, preferring an antecubital or large forearm vein, and observe the injection for extravasation. A 20-gauge or larger cannula is preferred for flow rates of 3 mL/s or more.
Radiographer at the scannerAt the scanner
Flags back if: No cannula can be sited that supports the protocol flow rate — for example only a 22-gauge hand or foot cannula for a CT angiogram needing 4–5 mL/s; or the only available access is a central line or port that is not labelled power-injectable; or an extravasation occurs.

Pathways

Big forks are separate pathways; the first whose conditions match is the one used.

Adults — pre-biopsy detection

Matches your inputsDefault

Role	Study & protocol	Why this answers the question
First line	MRI Prostate MRI Prostate — multiparametric (PI-RADS) usually appropriate	Each sequence answers a different question, which is why the protocol is multiparametric rather than long. High-resolution T2 provides the anatomy and is the dominant sequence in the transition zone, where cancer must be separated from nodular hyperplasia. Diffusion is the dominant sequence in the peripheral zone, where dense tumour cellularity restricts water motion and produces the low ADC that carries most of the diagnostic signal. The dynamic series adds focal early enhancement, whose defined role is to resolve equivocal peripheral zone findings. Acquired before biopsy, the study is clean of haemorrhage and can direct a targeted needle rather than merely confirm a systematic one.
Reasonable alternative	MRI Prostate MRI Prostate — biparametric (no contrast)	The same T2 and diffusion specifications without contrast, for pathways that have adopted a biparametric approach, for men in whom gadolinium is undesirable, and where table time and cannulation are the constraint on access. It transfers diagnostic weight onto the diffusion sequence, so its quality must be assessed explicitly and there must be a defined route to add the dynamic series at the same visit when diffusion is degraded.

Pitfalls

Accepting a request for MRI after a systematic biopsy has already been done. The sequence is inverted and the study is degraded for weeks.
Rectal gas distorting echo-planar diffusion so that the peripheral zone is misregistered — the commonest technical failure, and the reason preparation is part of the protocol.
A field of view too large or slices too thick to resolve capsular contact, which is the finding that changes surgical planning.
Treating a negative MRI as excluding cancer. It reduces but does not remove the need for biopsy, and the decision belongs with the urologist and the PSA density.
Extrapolated high b-value images generated from poor-quality acquired data, which inherit and amplify the noise.

Priors — what to pull first

Record the date of any previous biopsy. Within six weeks the peripheral zone is dominated by haemorrhage and the study will need repeating.
On active surveillance, the previous MRI is the comparator and the protocol should replicate it — a change in field strength or coil arrangement alters apparent lesion conspicuity.

What makes a good request

Pre-biopsy MRI improves detection of clinically significant cancer while reducing the number of men biopsied, and multiple large studies plus national guidance now place it before first biopsy rather than after a negative one.
PI-RADS version 2.1 defines the acquisition requirements as much as the scoring, and a study that misses them cannot be scored against it: high-resolution T2 in at least two planes at 3 mm slice thickness with no interslice gap and a 12-20 cm field of view; diffusion with a low b value of 0-100, an intermediate b value of 800-1000 from which the ADC map is calculated, and a high b value of 1400 or above either acquired or extrapolated; and a dynamic contrast series with temporal resolution of 15 seconds or better. It also revised transition zone scoring and the DWI/T2 dominance rules, so a report written against v2 and one written against v2.1 are not the same document — name the version in the report.
Biparametric protocols omitting contrast are non-inferior in several comparisons and are widely adopted for high-throughput pathways; the current scoring system nonetheless retains a specific tie-breaking role for contrast in equivocal peripheral zone lesions. Both positions are defensible and centres differ.
Timing after biopsy matters: haemorrhage both mimics and masks tumour, and a delay of at least six weeks is conventional where MRI has to follow biopsy.

Scoring this once it is done

The classification and risk tools this question ends in.

PI-RADS v2.1 (Prostate MRI)Prostate Volume & PSA Density PSMA-RADS 1.0 PROMISE Criteria / miTNM Staging (PSMA-PET)Pluvicto Dose Modification for Adverse Reactions

How these studies are acquired

Contrast, phases and timing for every study on the pathways above.

MRI Prostate — multiparametric (PI-RADS)MRI Prostate — biparametric (no contrast)

Confirm locally

MRI Prostate — multiparametric (PI-RADS): timings are typical — confirm against local protocol.
Timings, contrast volumes and rates above are typical published values. Your department's protocol, scanner and patient population decide the actual numbers.
Safety thresholds and premedication policy follow local policy where it differs from the cited guidance.

References

Implemented from the cited published sources. Educational and workflow support only; confirm against current guidelines and local policy before clinical use.