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MRI in Rectal Cancer

Kartik S Jhaveri, MD,FRCPCDirector , Abdominal MRIDirector, CME Program

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

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MRI “RECTUM” PROTOCOL

TORSO PA MUTLICHANNEL COIL

Diffusion Weighted Imaging-DWI

T2 –SAG,COR,AX

HI RES OBLIQUE T23D T2 ?

Multiphasic Gd-Enhanced Series

1.5T / 3T

MRI System

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Role of MRI :Rectal Cancer

Preoperative Staging & Treatment

Stratification

Post Neoadjuvant Therapy

Tumor Recurrence Evaluation

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Preoperative Staging

� Positive Surgical Margin = Recurrence� Neg. Surgical Margin = Curative Resection � Margins at Risk = Neoadjuvant ChemoRad

� Rectal MR Identify At risk / Positive margin sPrognostic features

. Treatment Stratification - Surgery vs Preop CRT

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SYNOPTIC MR REPORTING

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-TUMOR LOCALIZATION & SPHINCTERS-

-EXTRAMURAL SPREAD (T STAGE)

-CIRCUMFERENTIAL RESECTION MARGIN (CRM)

-EXTRAMURAL VASCULAR INVASION (EMVI)

-LYMPH NODES-N

-METASTASIS-M (Bones)

Preoperative Staging

-PERITONEAL REFLECTION

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TUMOR LOCALIZATION & SPHINCTERS

LOW 0-5cm, MID 5-10cm, UPPER 10-15cm

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SPHINCTERS

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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

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T2/T3

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T3

Desmoplastic Reaction vs T3

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DEPTH OF EXTRAMURAL INVASION (T3)

EXTENSIVE EXTRAMURAL SPREAD

POOR PROGNOSIS

Depth 5-yr Survival

<5mm 85%

>5mm 54%

*AJCC (2010)*

T3a <5mmT3b 5-10mmT3c >10mm

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CRM and MRI

� MRI : >5mm from CRM

� Pathology >1-2mm Negative Margin

MERCURY TRIAL MRI >1mm from CRM= Neg.Margin

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CRM

CRM >5mm CRM = 0 mm

CRM & Satellite Tumoral Nodule

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Peritoneal Reflection

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Extramural Venous Invasion (EMVI)

Discrete Serpiginous or Tubular Intermediate Signal Projections in Mesorectal fat MRI –Sens 62%

- Spec 88%

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T4

Mucinous Tumor- Poor CRT response 20

Brown G et al. “Morphologic predictors of lymph nodestatus in rectal cancer with use of highspatial-resol ution

MRI with histopathologic comparison”.

Radiology 2003; 227:371–377

Morphologic criteria

Irregular Contour and Hetergoneous signal

Criteria Of Nodal Metastasis

Size criteria>8mm (round) > 10mm (oval)

Lateral Pelvic Nodes

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PREOP CRTNO PRE/POST CRT = LATERAL PELVIC RECURRENCE

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MRI Limitations

� T1 VS T2

� T3 –DESMOPLASTIC REACTION-OVERSTAGING

� CRM - Thin Patient- Anterior wall tumor- Low rectal tumor

• NODES - Normal sized nodes ?