MRI in Rectal Cancer. Kartik S Jhaveri, MD,FRCPC Director, Abdominal MRI Director, CME Program

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1 MRI in Rectal Cancer Kartik S Jhaveri, MD,FRCPC Director, Abdominal MRI Director, CME Program

2 DISCLOSURES No Relevant Disclosures 2

3 OBJECTIVES Imaging of Rectal Cancer Why MRI? MR Protocol MR Anatomy Preoperative Staging/Treatment Planning Special Considerations: Low Rectal Cancer 3 Post CRT MRI Evaluation

4 BACKGROUND Colorectal Cancers are the Second most common cause for cancer related deaths Local pelvic recurrence after surgical resection is a major concern Usually leads to Incurable disease and poor QOL Reduce pelvic recurrence - Increase disease free survival Primary goal of Staging is to triage treatment 4

5 STAGING - IMAGING ERUS LOCAL MRI METASTASES CT/PET-CT 5

6 ERUS VS MRI S T T1 VS T2 T2 VS T3 ERUS MRI < > ERUS M A T3 VS T4 MRI >ERUS R G E N MRI >ERUS I M CT/PET-CT 6

7 ERUS VS MRI S T T1 VS T2 T2 VS T3 ERUS MRI < > ERUS M A T3 VS T4 MRI >ERUS R G E N MRI >ERUS I M CT/PET-CT 7

8 ERUS VS MRI S T T1 VS T2 T2 VS T3 ERUS MRI < > ERUS M A T3 VS T4 MRI >ERUS R G E N MRI >ERUS I M CT/PET-CT 8

9 ERUS VS MRI S T T1 VS T2 T2 VS T3 ERUS MRI < > ERUS M A T3 VS T4 MRI >ERUS R G E N MRI >ERUS I M CT/PET-CT 9

10 ERUS VS MRI ERUS Bulky or Stenotic tumors Very High or Very Low Mass Mesorectal Fascia LN detection outside mesorectum Post neoadjuvant response evaluation? MRI MRI is also performed without Endoluminal device insertion 10

11 MRI RECTUM PROTOCOL TORSO PA MUTLICHANNEL COIL Diffusion Weighted Imaging-DWI 1.5T / 3T MRI System T2 SAG,COR,AX HI RES OBLIQUE T2 3D T2? Multiphasic Gd- Enhanced Series 11

12 MR PARAMETERS-1.5T Sequence Slice(mm) Matrix Time(min) FOV(mm) LOCS T1 AXIAL GRE 5/1 256 X T2 FSE SAG 4/1 320 x T2 FSE COR 4/1 320 x T2 FSE AXIAL 4/1 320 x T2 HI RES OBLIQUE 3/0 320 x T2 SPACE/FRFSE 1 x 1 x x DWI-b0,50,400,1000 4/1 128 x T1 SAG/AX Gd 3D VIBE/LAVA 4/0 320 x x

13 Hi Res Angled T2 MR High-resolution 3mm slice thickness Matrix > 256 x 256/320 x320 Perpendicular to the tumoral axes 13

14 Hi Res Angled T2 MR High-Quality MRI Is A Fundamental Requirement To Obtain Accurate Anatomical Information Of The Tumoral Relationships 14

15 Hi Res Angled T2 MR High-Quality MRI is a fundamental requirement to obtain accurate anatomical information of the tumoral relationships 15

16 DWI Post CRT Evaluation Tumor recurrence LN,Tumor visualization T2 DWI GAD 16

17 CONTRAST Rectal? Intravenous? 17 Endoluminal Contrast DYNAMIC RUN Tumor Detection Post CRT LN Characterization

18 18 ANATOMY

19 T2 CORONAL Levator ani Int Sphincter Puborectalis Ext Sphincter 19 NORMAL MRI ANATOMY

20 T2 SAGITAL 20 Tumor Localization Anal Verge Adjacent Organs- Vagina,Prostate,SV Anterior Peritoneal reflection

21 T2 AXIAL Muscularis Propria Submucosa 21

22 T2 AXIAL 22 MESORECTAL FASCIA

23 MESORECTUM SUGICAL IMPLICATIONS: TOTAL MESORECTAL EXCISION (TME) Mesorectal Fascia = Excisional Margin in TME 23 = Circumferential Resection Margin(CRM)

24 Peritoneal Reflection AXIAL T2 24 Peritoneum attaches in a V shaped manner onto the anterior surface of upper rectum Seagull Sign

25 Peritoneal Reflection Sagittal T2 Denonvilliers Rectovaginal Fascia 25

26 Role of MRI :Rectal Cancer Preoperative Staging & Treatment Stratification Post Neoadjuvant Therapy Tumor Recurrence Evaluation 26

27 Preoperative Staging Positive Surgical Margin = Recurrence Neg. Surgical Margin = Curative Resection Margins at Risk = Neoadjuvant ChemoRad Rectal MR Identify At risk / Positive margins Prognostic features. Treatment Stratification - Surgery vs Preop CRT 27

28 28 SYNOPTIC MR REPORTING

29 Preoperative Staging -TUMOR LOCALIZATION & SPHINCTERS - -EXTRAMURAL SPREAD (T STAGE) -CIRCUMFERENTIAL RESECTION MARGIN (CRM) -PERITONEAL REFLECTION -EXTRAMURAL VASCULAR INVASION (EMVI) -LYMPH NODES-N 29 -METASTASIS-M (Bones)

30 TUMOR LOCALIZATION & SPHINCTERS 30 LOW 0-5cm, MID 5-10cm, UPPER 10-15cm

31 31 SPHINCTERS

32 T Stage T1 invades sub-mucosa T2 invasion of circular/longitudinal layers T3 invasion through muscularis T4 direct invasion of other organs or visceral peritoneum 32

33 33 T1/T2

34 34 T2

35 35 T3

36 DEPTH OF EXTRAMURAL INVASION (T3) Depth 5-yr Survival *AJCC (2010)* <5mm 85% >5mm 54% T3a <5mm T3b 5-10mm T3c >10mm EXTENSIVE EXTRAMURAL SPREAD POOR PROGNOSIS 36

37 37 T2/T3

38 T3 Desmoplastic Reaction vs T3 38

39 39 Circumferential Resection Margin -CRM

40 Circumferential Resection Margin (CRM) CIRCUMFERENTIAL RESECTION MARGIN (CRM) CIRCUMFERENTIAL? 40

41 Visceral Peritoneum and CRM Courtersy Dr. Mahmoud Khalifa, Dept of Pathology,Toronto 41

42 CRM and MRI MRI : >5mm from CRM Pathology >1-2mm Negative Margin MERCURY TRIAL MRI >1mm from CRM= Neg.Margin 42

43 CRM 43 CRM >5mm CRM = 0 mm

44 44 CRM & Satellite Tumoral Nodule

45 45 Peritoneal Reflection

46 EXTRAMURAL VASCULAR INVASION (EMVI) Discrete Serpiginous or Tubular Intermediate Signal Projections in Mesorectal fat MRI Sens 62% - Spec 88% 46

47 T4 47 Mucinous Tumor- Poor CRT response

48 LOW RECTAL CANCER Adenoca in 0-5cm from anal verge High Positive CRM rates Permanent Stoma Anal Ca(SCC) is NOT Rectal cancer(adenoca) 48

49 LOW (ANO)RECTAL CANCER Relation to Anorectal Junction Adv.T2 49 T3

50 LOW (ANO)RECTAL CANCER T4 50

51 LOW (ANO)RECTAL CANCER Courtesy Dr. Fayez Qureshy,Colorectal Surgery, UHN 51

52 N STAGE N0: No regional lymph node metastasis N1: Metastases in 1 to 3 nearby lymph nodes N2: Metastases in 4 or more nearby lymph nodes N3 : Distant LN Rectum : External &Common iliac and abdominal 52

53 LYMPH NODES Accuracy of Different Techniques Test Sens Spec ERUS CT/(PET) 55 74/(~80) MRI Bipat et al. Rectal cancer: local staging and assessment of lymph node involvement with endoluminal US, CT, and MRI a meta-analysis.. Radiology, 2004; 232:

54 Criteria Of Nodal Metastasis Size criteria >8mm (round) > 10mm (oval) Morphologic criteria Irregular Contour and Hetergoneous signal Brown G et al. Morphologic predictors of lymph node status in rectal cancer with use of highspatial-resolution MRI with histopathologic comparison. Radiology 2003; 227:

55 DWI Increased Detection of <1cm Nodes Differentiation of Benign vs Malignant? - Not Reliable 55

56 Lateral Pelvic Nodes PREOP CRT NO PRE/POST CRT = LATERAL PELVIC RECURRENCE 56

57 MRI Accuracy T Staging : % N Staging : % CRM : 95 % MRI is more accurate in predicting free resection margin than T stage!!! Beets-Tan RG et al. Lancet 2001 Brown G et al. BJS 2003 & RSNA 2004 Nagtegaal I et al. Am J Surg Path

58 MRI PITFALLS IN T STAGE T1 VS T2 T3 DESMOPLASTIC REACTION- OVERSTAGING CRM -Thin Patients - Anterior wall tumor - Lower rectal tumor NODES- Normal sized nodes 58

59 POST CRT EVALUATION Direct Surgical Approach after preop neoadjuvant therapy without repeat MR? ~ 80% Respond (~10-20% complete) Major Pelvic Surgery Hi PostOp Morbitiy(40-50%) Why Post CRT MRI? -Assess Tumor Response -Reassess Tumor Resectabiity Threat to Margin? -Personalize Surgery based on Response 59 Wait & Watch vs TME vs APR?

60 TUMOR REGRESSION GRADING AJCC Tumor Regression Grade (Pathology) Description Tumor Regression Grade No viable cancer cells TRG 0 (Complete response) Single cells or small groups of cancer cells TRG 1 (Near complete response) Residual cancer outgrown by fibrosis TRG 2 (Partial response) Minimal to no tumor kill TRG 3 (No response) MRI No tumor signal mrtrg 1 Predominant Fibrosis(minimal tumor) mrtrg 2 Mixed fibrosis and tumor mrtrg 3 Predominant Tumor mrtrg 4 Tumor(little fibrosis) mrtrg 5 60 Patel U et al. AJR:199, October 2012

61 POST CRT EVALUATION :MRI T stage ~50% (T2WI) ; DWI (improves accuracy) T2 MR Volumetry - Good TRG correlation NPV for CRM : 98% Overall CRM ~77% mrtrg : Predictive of CRM involvement Nodes ~72% Memon S et al.colorectal Dis Apr 61

62 POST NEOADJUVANT EVALN mrtrg4/5 - NO RESPONSE / PROGESSION 62

63 POST NEOADJUVANT EVALN mrtrg1 (NEAR COMPLETE RESPONSE) 63

64 SUMMARY Endorectal US for T1 VS T2 MRI ( ERUS) FOR Stage T3 and Higher High Quality MRI Critical -Hi Res Angled Images MRI most accurate for CRM Synoptic Reporting and MDT Meetings 64