Prostate MRI: Revolution, now evolution · (R)Evolution of Prostate Talks RSNA 2001 Understand the application of Prostate MR for staging RSNA 2003 Imaging Prostate Cancer: What the

Prostate MRI:

Revolution, now evolution

XXVIIIth Congress of the Hungarian Society of Radiology

24th June 2016

Tristan Barrett

University Lecturer and Honorary NHS Consultant Addenbrooke’sHospital, Cambridge, UK

(R)Evolution of Prostate Talks

RSNA 2001 Understand the application of Prostate MR for staging

RSNA 2003 Imaging Prostate Cancer: What the Radiologist Should Know

RSNA 2005 Prostate Cancer Imaging: Past, Present, and Future

RSNA 2007 Prostate MR: Relevance, Current Practices, and Evolving

Techniques

RSNA 2010 Prostate MRI: Ready for Prime Time

BIR 2014 Prostate mp-MRI: Can it facilitate a paradigm shift in

management?

“Old” clinical paradigm is Limited

Prostate-Specific Antigen

– ≥4.1 ng/ml: PPV of only 30% for detecting cancer 1

– 2.5 - 4 ng/mL: cancer is detected in 37% of biopsies 2

Digital Rectal Examination

– “Getting worse”: PPV 58% in 1950s but only 9.7% in the post-

PSA era 2

Transrectal Ultrasound-guided Biopsy

– Particularly under-samples anteriorly, medially, apex

– Fails to detect 47% 3 and undergrades 38% of tumours 4

[1] Adhyam M, et al. Indian J Surg Oncol. 2012 ; 3(2):120-9 [2] Schröder, et al. J Urol 2000; 163(3):806-12

[4] Kvåle, et al. BJUI. 2009;103:1647-54[3] Lecornet, et al. J Urol 2012;188:974e80

• Prostate MRI previously used for local T-staging

• Anatomical imaging sensitive but not specific

– “multiparametric” MRI with functional imaging allows

↑lesion detec>on and (possibly) characterisa>on

• There are several drivers to lesion identification

– Targeting repeat biopsies in high risk patients

– Risk stratification at AS enrolment

– Potential for focal therapies

Evolving Role of Imaging

Diffusion-weighted imaging

• Paradigm: tumours show restricted diffusion

• ↑cellularity, ↑nuclear : cytoplasmic ratio

Dynamic contrast-enhanced (DCE) MRI

• Paradigm: tumours have “leaky” vessels

• ↑angiogenesis; disorganized neovasculature

MR Spectroscopy (MRSI)

• Paradigm: tumours have ↑ cells and ↑prolifera>on

• ↑Choline and ↓citrate (benign marker)

Available functional sequences

Khalifa MHK, Hafez A, Elnoueam K, A. Elabbady, et al. DOI: 10.1594/ecr2015/C-0590

Acc

ura

cy (

%)

100

90

80

70

60

50

40

30

20

10

0

↑ Sequences = ↑ Accuracy

Mowatt G, et al. Health Technol Assess. 2013; 17(20):vii-xix, 1-281

Est

ima

ted

He

alt

hca

re C

ost

(£

)↑ Sequences = ↑↑ £Cost

Current PIRADS (v2) recommends

• Axial T2WI and DWI, DCE 1

• Why has MRSI been dropped?

– Specificity 100% (!) - Good for characterisation 2

– Sensitivity 16% - Poor for lesion detection

• Should we also drop DCE?

[2] Turkbey B, et al. J Urol. 2011;186(5):1818-24[1] Barrett T, et al. Clin. Rad. 2015; 70: 1165-76

Should we also drop DCE?

The prostate is NOT the breast– Benign conditions such as prostatitis and BPH can demonstrate early

contrast wash-in and wash-out

– Tumours more commonly have a Type II curve

– Inability of curve-typing to accurately differentiate malignancy 2

[2] Hansford BG, et al. Radiology. 2015;275:448-57[1] Macura KJ, et al. Radiographics. 2006; 26:1719-34

Type I: 83% benign; 9% cancer

….………………………………..

Type III: 90.4% spec for cancer 13

2

1

Evolving Role of DCE-MRI

• Cine-loop of wash-in, simple wash-out curves +/- analysis

Focal AND Enhances earlier vs (normal) tissue AND

Matches suspicious T2W +/- DWI area

Now: DCE scored simply as

“positive” or “negative”

Evolving Role of DCE-MRI

• Cine-loop of wash-in, simple wash-out curves +/- analysis

Focal AND Enhances earlier vs (normal) tissue AND

Matches suspicious T2W +/- DWI area

Now: DCE scored simply as

“positive” or “negative”

How good is mp-MRI?

• mp-MRI for lesion detection– Gleason 3+4 lesions ≥0.5 cm3 (≈ 10 mm sphere) 1

– Gleason ≥4+3 lesions ≥0.2cm3 (≈ 7 mm sphere) 1

– Sens 74%, spec 88% 2

– Will “never” detect all small vol GS 6… may be a good thing

• … But it’s difficult– Known learning curve for reporting 3

– Technical factors (coil, sequences), Patient factors (BPH, previous treatment, biopsy artefact)

[1] Puech, et al. Eur Rad. 2009;19:470-80 [2] de Rooij M, et al. AJR. 2014; 202(2):343-5

[3] Gaziev G, et al. BJU Int. 2016;117(1):80-6

Should we offer MRI before

biopsy?

MRI pre-biopsy

• “Most” who have TRUS Bx will go on to have MRI

– Why not MRI pre biopsy?

– Avoids biopsy related artefact

– Allows triage of biopsy “type” +/- targeting

• Even IF no increase in MRIs done

– Harder to schedule “within 5 days” vs “4-6 weeks”

– Report turnaround time

Local experience

• Official part of pathway since 5th October 2015

– Aim MRI in 5 days, clinic in 7 days (2 days to report)

• Pre-Pre-Biopsy MRI

– 607 MRs in 39 wks 5/1/15 - 4/10/15 (15.6 per week)

• Post-Pre-Biopsy MRI

– 661 MRs in 35 wks 5/10/15 – 5/6/16 (18.9 per week)

↑3.3/wk (↑ ~20%)

MRI numbers Pre vs Post

Totals

• Oct 2015 – Jan 2016 “Initial spike”

– 274 MRs in 14 wks 5/10/16 - 10/1/16 (19.9 per wk)

• Jan – June 2016

– 383 MRs in 21 wks 11/1/16 - 5/6/16 (18.2 per wk)

• Jan – June 2015

– 350 MRs in 21 wks 12/1/15 - 7/6/15 (16.7 per wk)

↑1.5/wk (↑ <10%)

… “Probably” no increase (vs background) after initial spike

MRI +ve MRI -ve

Small or

Anterior lesion

Posterior

lesion

Transrectal Biopsy

Transperineal Biopsy

NothingLow

clinical risk

High clinical

risk

Template Biopsy

No Biopsy

Future: New Diagnostic Pathway?

Conclusions

• Revolution has occurred

– mpMRI established in the work-up of prostate cancer

• Evolution now in process

– Spectroscopy dropped

– DCE role significantly changed

• Further evolving considerations

– MRI pre-biopsy?

– Role of MRI in follow-up of AS needs defining

– Choice of “short” or “detailed” protocols?