Prostate MRI: Who needs it? Fergus Coakley MD, Professor of Radiology and Urology, Vice Chair for Clinical Services, Chief of Abdominal Imaging, UCSF Abdominal Imaging Magnetic Resonance Science Center Anatomic Pathology Cho Cr Cit Cho Cr Cit Radiation Oncology Normal Cancer Urology
Objectives Provide the evidence-basis for MRI of prostate cancer Describe the role of MRI of prostate cancer according to disease risk category
Importance of prostate cancer 200 Breast Average years of life lost: (1000s) 150 100 Prostate Breast = 13.5 Prostate = 6.1 50 ACS 2009 estimates 0 Brit J Can 2005; 92: 241-245 Incidence Mortality
Risk stratification Free of PSA recurrence LOW INTER HIGH Several risk stratification schemes described D Amico system common Important predictor of outcome Months from brachytherapy Potters et al. J Urol 2008; 179: S20-4 D Amico et al, J Urol 2000; 164: 759-763 1 2 3 4 5 6 7 8 9 PSA <10 <10 10-20 >20 <10 10-20 10-20 >20 >20 Gleason DRE % +ve biopsy 2-6 & T1-T2A 2-6 & T1-2A 7 or T2B 8-10 or T2C 2-6 & T1-T2A 7 or T2B 7 or T2B 8-10 or T2C 8-10 or T2C <34 34-50 <34 <34 >50 34-50 >50 34-50 >50
Prostate MRI - basic SE T1 axial Aortic bifurcation to symphysis pubis TR/TE=700/8; 5/1mm; FOV=24; 256x192; 1 NEX Frequency direction transverse FSE T2 axial Prostate (high resolution) TR/TE =5000/96; 3/0mm; FOV=14; 256x192; 3 NEX Frequency direction anteroposterior FSE T2 coronal Prostate (high resolution) TR/TE =5000/96; 3/0mm; FOV=14; 256x192; 3 NEX
Prostate MRI - advanced Spectroscopic imaging: 10-20 minute sequence High choline and low citrate in cancer Improves detection/characterization Perfusion: Cancer enhances faster and brighter than normal peripheral zone tissue and has greater washout T2 T1 pre T1 post Diffusion: Reduced diffusion in cancer Clinical role under investigation T2 ADC
MRI for low risk disease? A healthy 72 year old man is found to have a PSA of 8.4 ng/ml. DRE is unremarkable. Gleason 6 cancer is found in 15% of one sextant biopsy core. Based on existing guidelines, should this patient undergo MRI, or any other imaging?
Existing guidelines Source Recommendations ACR Bone scan, CT, MRI if PSA > 10 or Gleason > 6 AUA Bone scan if PSA > 20, poorly differentiated, or T3 CT, MRI if PSA > 25 Utility of endorectal MRI/MRSI not determined AJCC Bone scan, CT, MRI if PSA > 20 or Gleason > 7-8 Radiology 2007; 243: 28-53
No imaging for low risk patients? Likelihood of locally advanced or metastatic disease is low Risk group ECE SVI Node positive Lee et al, Int J Radiat Oncol Biol Phys 2007; 68: 1059-64 Pettus et al. J Endourol 2008; 22: 1021-1025 Gleave et al, Urology 1996; 47: 708-12 Rhoden et al, Int Braz J Urol 2003; 29: 121-125 Hirobe et al, Jpn J Clin Oncol 2007; 37: 788-792 Positive bone scan Low 9% 1% 1.3% 0% Intermediate 20% 5% 6% 1.6-4.5% High 47% 30% 20% 21-41%
Possible roles in low risk disease Map tumor prior to focal therapy: 100% PPV if MRSI volume > 0.54 cc Select patients for active surveillance: Az of 0.80 with MRI versus 0.73 without Monitor patients on active surveillance: MRI/MRSI progression correlates with PSA velocity Chang et al, ARRS AGM, 2011 Shukla-Dave et al, BJU Int 2007; 99: 786-793 Coakley et al, BJU Int 2007; 99: 41-5
Imaging for higher risk patients? Likelihood of locally advanced or metastatic disease is high Risk group ECE SVI Node positive Lee et al, Int J Radiat Oncol Biol Phys 2007; 68: 1059-64 Pettus et al. J Endourol 2008; 22: 1021-1025 Gleave et al, Urology 1996; 47: 708-12 Rhoden et al, Int Braz J Urol 2003; 29: 121-125 Hirobe et al, Jpn J Clin Oncol 2007; 37: 788-792 Positive bone scan Low 9% 1% 1.3% 0% Intermediate 20% 5% 6% 1.6-4.5% High 47% 30% 20% 21-41%
MRI findings in T3 disease Focal irregular bulge NVB asymmetry Obliteration of RP angle Seminal vesicle invasion 24-38% 21-38% 24-50% 43-71% Sens 77-88% 81-95% 81-95% 99% Spec 58-65% 56-70% 57-71% 95-97% Acc Radiology 1997; 202: 697-702 and 2005; 237: 541-549
MRI and staging MSKCC study of 344 patients: MRI (+MRSI in 216) prior to radical prostatectomy Likelihood of ECE rated from 1-5 based on reports 83/344 (24.1%) had ECE at pathology Univariate and multivariate ROC analysis : PSA - Highest % of cancer in cores Gleason score - % of cancer-positive cores DRE stage - Presence of PNI Radiology 2004; 232: 133-139
Results Univariate: MRI had highest A z (0.74) Multivariate: Better staging with MRI (0.84 vs 0.77; p = 0.02)
The BIG issue... Gleason 6 left apex PSA 9.2 EIGHT years later PSA 11.9 Gleason 6 right apex PSA 5.8 ONE year later PSA 10.8
Prognostic role of MRI NS T2 T3 Significant Pre-RRP MRI (n = 1025) 5 year PSA outcome v. MR stage D Amico et al, J Urol 2000; 164: 759-763 Significant Low (1-3: 61%) Intermediate (3-6:19%) High (7-9: 20%) 1 2 3 4 5 6 7 8 9 PSA <10 <10 10-20 >20 <10 10-20 10-20 >20 >20 Gleason DRE % +ve biopsy 2-6 & T1-T2A 2-6 & T1-2A 7 or T2B 8-10 or T2C 2-6 & T1-T2A 7 or T2B 7 or T2B 8-10 or T2C 8-10 or T2C <34 34-50 <34 <34 >50 34-50 >50 34-50 >50
Outcome studies Pre-EBRT studies: MRI alone - ECE only independent predictor of metastases MRI and MRSI - MRSI tumor volume predicts of PSA failure; MRI tumor size & SVI predict metastases All-comers study: Gross ECE/SVI worsens prognosis Radiology 2008; 247:141-6 Int J Rad Onc Biol Phys 2009; 73: 665-71 Muglia et al, RSNA 2009 Risk Gross ECE/SVI Low 1/1085 (0.1%) Inter 25/489 (5.1%) High 40/203 (19.7%)
Illustrative case 58-year old, Gleason 6, PSA 6.1 T2b Rising PSA 4 years later (after brachytherapy) AND FINALLY NECT #1
Conclusions Difficult organ and disease to image MRI more useful in intermediate and high risk disease: Contributes to staging and prognostication Role in low risk disease evolving: DO NOT image for T3+, N+, M+ disease MAYBE image for selection/monitoring of active surveillance or planning focal therapy