MRI in Carcinoma Rectum

1. CRC - Locoregional Imaging
Dr Manoj K S DMRD MD RD DNB RD
Consultant Radiologist KIMS

2. Multidisciplinary approach
Rectal cancer staging has three crucial components: local
staging, metastatic disease evaluation, and investigation
of other bowel segments for synchronous tumors.
Diagn Interv Radiol 2014; 20:390–398 Ümit Tapan, Mustafa Özbayrak, Servet Tatlı MRI in local staging of rectal cancer
“A multidisciplinary team consisting of a MRI radiologist,
colorectal surgeon, medical and radiation oncologists, and
gastrointestinal pathologist play a crucial role in overall care
in patients with rectal cancer”
AJR:199, July 2012 Vivek Gowdra Halappa1etaal

3. Rectal Anatomy
The rectum varies in length from 10 to 15 cm from
the upper end of the anal canal to the recto-sigmoid junction.
Rectum divided into three parts:
These three parts are defined from the anal verge (AV) as
Lower rectum (0–5 cm), Middle rectum (5–10 cm), and
Upper rectum (10–15 cm).
The rectosigmoid junction is considered to be at the level of
S3 by anatomists and at the level of sacral promontory by surgeons.
The distal ring is regarded as the muscular anorectal ring by
surgeons and as the dentate line by the anatomists.

4. imaging
structural
dynamic
molecular
tumor
margins
nodes
relations

5. Local Staging Imaging Modalities
Endorectal Ultrasound {ERUS}
MRI [ HR MRI 1.5 T / 3 T / Endorectal coil ]
MDCT
PET CT
PET MRI •Circumferential resection margin (CRM)
•Extramural venous invasion (EMV),
•Sphincter complex status
•Extra mesorectal nodes
Why MRI

6. MRI in Ca RectumHigh-resolution T2-weighted imaging is the key sequence in the magnetic
resonance (MR) imaging evaluation of primary rectal cancer. This
sequence generally consists of thin-section (3-mm) axial images obtained
orthogonal to the tumor plane, with an in-plane resolution of 0.5–0.8 mm
MR imaging of primary rectal tumors can be used to assess the tumor in
terms of (a) stage; (b) depth of invasion outside the muscularis
propria; and (c) relationship to the mesorectal fascia, anal sphincter,
and pelvic sidewall.
The American Joint Committee on Cancer (tumor-node-metastasis
[TNM]) guidelines have been used to develop MR imaging criteria for the
staging of primary rectal tumors

7. Standardized Technique
• 3mm, 16cm-18cm FOV, 4-6
NSA, 256x256 matrix, TR
>3,000, TE 80-100, ETL 16
• In plane resolution 0.6mm x
0.6mm
• Brown G, Daniels IR, Richardson C et al
Techniques and trouble-shooting in high
spatial resolution thin slice MRI for rectal
cancer.
Br J Radiol 2005; 78:245-251.

8. High-Quality MRI is a fundamental requirement
to obtain accurate anatomical information of the tumoral relationships

9. MRI : Rectal anatomy
The rectal wall is composed of three layers:
Mucosa : A fine low-signal line
Submucosa : High-signal layers
Muscularis propria : Two low-signal layers
(outer longitudinal and inner circular) at T2-weighted images
The rectum is surrounded by mesorectal fat containing lymph
nodes, superior hemorrhoidal vessels, and fibrous tissue,
which are represented as high signal intensity surrounding the
muscularis propria.

10. 3 Tesla MRI
submucosa
muscularis
MRF
mucosa

11. Mesorectal Fascia = Excisional Margin in TME
= Circumferential Resection Margin(CRM)
CRM is a term referring to the surgically dissected surface of the rectum corresponding to the
non-peritonealized part of the rectum. It is applicable to tumors below the peritoneal reflection of the rectum
For upper rectal tumors, the CRM exists only posteriorly and in upper-mid rectal tumors it is posterior and
lateral

12. The MRF is only circumferential for rectal tumours below the anterior peritoneal reflection.
The MRF does not apply to anterior, peritonealized surface of the anterior rectum above the
anterior peritoneal reflection.

13. ERUS in Ca Rectum

14. T Stages of TNMStage T1 tumors are confined
to the submucosa;
Stage T2 tumors invade the
muscularis propria (arrows),
which consists of a circular
inner muscle layer and a
longitudinal outer layer;
Stage T3 tumors extend beyond
the muscularis propria;
Stage T4 tumors involve
adjacent organs or the
peritoneum.

15. MRI versus CT
LOW 0-5cm, MID 5-10cm, UPPER
10-15cm

16. 3 Tesla MRI

18. Meta-analysis of 21 studies [from ESGAR]
Magnetic resonance imaging for the clinical management of rectal cancer patients:
recommendations from the 2012 European Society of Gastrointestinal and Abdominal
Radiology (ESGAR) consensus meeting

19. MRI Protocol

20. HR MRI Protocol
Diagn Interv Radiol 2014; 20:390–398 Ümit Tapan, Mustafa Özbayrak, Servet Tatlı MRI in local staging of rectal cancer

21. HR MRI Protocol
Imaging in rectal cancer with emphasis on local staging with MRI
Supreeta Arya, Deepak Das, Reena Engineer1, Avanish Saklani2
Indian Journal of Radiology and Imaging / May 2015 / Vol 25 / Issue 2 Department of Radio-Diagnosis, 1Radiation Oncology, and 2Surgical
Oncology, Tata Memorial Centre, Mumbai, Maharashtra,
India

22. MRI Rectum Technique
Summary of Essentials
• Scan duration = quality 7mins average length of each
sequence
• 4-6 NSA/NEX and T2- FSE / TSE /FRFSE
• 0.6mm x 0.6mm x 3mm = 1.1mm3 voxel
• Adequate coverage – 5cm above top of tumour
• Perpendicular to the rectal wall
• Low rectal cancer – parallel to anal canal
• Ensure discontinuous deposits are covered on high res
• Antispasmodics -Buscopan
• Saturation Bands
• Firm coil placement with secure abdominal compression

24. Rad-path correlation
The Rectal doughnut

25. Rad-path correlation
The Rectal doughnut
T1 stage tumors extend upto the submucosa, while tumors extending into
the muscularis propria without extension into perirectal tissues are T2 .
It is not possible to reliably distinguish between T1 and T2 tumors on
MRI (from Dr Gina Brown et al)

26. T2 Tumor
T2 : invasion of circular/longitudinal layers

27. CRM status:
• A tumor–MRF distance >2 mm is CRM negative
• A distance of <1 mm between the advancing tumor
edge and MRF is indicative of a CRM-positive status
Also, CRM positivity could be due to tumor/ perirectal
nodes / deposits / tumor stranding reaching <1 mm of
the MRF
• When the tumor/node/deposit–MRF distance is
between 1 and 2 mm,the CRM is regarded as
“threatened”

28. Measuring depth of extramural spread
Subclassification of T3 based on prognostic patterns
T3 Spread into perirectal fat
T3a Tumor extends <5 mm beyond the muscularis propria
T3b Tumor extends 5-10 mm beyond the muscularis propria
T3c Tumor extends >10 mm beyond the muscularis propria

29. Nodal anatomy & MRI Correlation
Two MRI criteria in perirectal nodes favor metastases: (a) heterogeneity of signal
intensity
on T2W sequences and (b) irregular margins
Size criteria are unreliable as 30-50% metastatic nodes in rectal cancers are <5 mm in size
Afferent lymphatic
Efferent lymphatics and
vessels
Medullary sinus
Follicle
Marginal sinus
Capsule
Morphologic criteria
Size > 8mm/10mm short axis

30. Lymph node border and signal intensity –measuring
size of nodes worsens results
• Node positive if either irregular border or mixed signal
intensity was demonstrated, the sensitivity, specificity
were high.
• Metastases were demonstrated in 51/56 nodes (91%,
95% CI 81% to 96%) with either an irregular border or
a mixed intensity signal.
• Only 9/225 nodes (4%, CI 2.1% to 7.4%) with smooth
borders and a uniform signal contained metastases.
• Size of node bears no relationship to malignant risk
Dr Gina Brown et al

31. Extramural vascular invasion (EMVI)
Extramural vascular invasion (EMVI) is a
pathologic, microscopic feature that refers to
invasion of large vessels deep to the muscularis
propria and has consistently been shown to be an
independent, negative prognostic factor in terms
of survival.
EMVI Negative
• Pattern of tumour extension through muscularis
propria is not nodular or no tumour extension in
the vicinity of any vascular structure.
• If stranding is demonstrated near extramural
vessels, these vessels are of normal caliber with
no
definite tumour signal within
EMVI Positive
• Intermediate signal intensity within vessels in the
vicinity of the tumour or obvious irregular vessel
contour
Smith NJ, Barbachano Y, Norman AR, Swift RI, Abulafi AM, Brown G. Prognostic significance of
magnetic resonance imaging-detected
extramural vascular invasion in rectal cancer. Br J Surg. Feb 2008;95(2):229-236

32. Extramural vascular invasion (EMVI)
Discrete Serpiginous or Tubular Intermediate Signal Projections in Mesorectal fat
MRI –Sens 62%
- Spec 88%

33. ESGAR Recommendations
Local invasion beyond the rectum
A range for T-category should be reported (i.e., T2/early T3)
if a definitive T-category cannot be accurately assessed
Spiculation of the perirectal fat should be reported as a
“T2/early T3 tumour
Definite invasion: loss of intervening fat plane and
corresponding T2 signal abnormality within the organ.
Possible invasion: loss of intervening fat plane and no
corresponding T2 signal abnormality within the organ.
No invasion: preservation of the intervening fat plane

34. Ca Rectum - local invasion
Invasion of adjacent organs
Bladder, ureter, prostate, uterus/vagina, sacrum and/or
internal and external iliac vessels.
Invasion of the Levator Ani
Puborectalis, pubococcygeus and/or ileococcygeus.
Invasion of the Pelvic Side Wall
Pelvic side wall muscles (obturator internus, piriformis and
coccygeus) and/or internal iliac artery and vein.
In general, tumours invading the pelvic side wall are
considered unresectable

35. Ca Rectum - local invasion

36. Negative CRM (defined as > 1 mm) is associated with a
significantly lower risk of local recurrence than a positive
CRM (defined as < 1 mm) Quirke P, Durdey P, Dixon MF, Williams NS. Local recurrence of rectal
adenocarcinoma due to inadequate surgical resection. Histopathological study of lateral tumour spread and surgical excision.
Lancet. Nov 1 1986;2(8514):996-999
• The minimum distance to the MRF should be reported for all T2 or higher
stage tumours where the MRF can be adequately seen or can be reasonably
estimated.
• The minimum distance to the MRF refers to the shortest distance of the
definitive tumour border to the MRF, where the definitive tumour border is the
nodular or pushing border of the tumour and does not include spiculations or
haziness of the perirectal fat.
• If it is not possible to reasonably estimate the MRF, the minimum distance to
the MRF should be reported as “unable to assess”.
• The distance to the MRF should be reported as “not applicable” for tumours
above the peritoneal reflection involving the peritonealized portion of the
rectum (including T4a tumours).
• For T4 tumours invading adjacent structures, the distance to the MRF should
be reported as “0”.

37. Low rectal cancer
Clinically, low rectal cancer is defined as rectal cancer
located 0 to 5 cm from the anal verge.
Low rectal cancers have been classified on MRI into two
categories relative to the top border of puborectalis as
suggested by the MERCURY group.
These categories are:
(i) Tumours in which the lower exent of the tumour is
clearly above the top border of puborectalis and
(ii) Tumours in which the lower extent of the tumour at or
below the top border of puborectalis

38. Key Bioimaging markers
for poor outcome at baseline and
post CRT
• 1mm TME plane CRM involvement on MRI
• Depth of T extramural spread >5mm
• Presence of MRI detected contiguous or
discontinuous venous invasion or vascular (non-
nodal) tumour deposits
• MRI detected mucinous tumours
• Tumour spread into or beyond the intersphincteric
plane
• MRI TRG status
Dr Gina Brown : 2015 ,Best Practice for Rectal Cancer Staging

39. Features that have no adverse prognostic
significance on MRI
• >1mm distance of tumour to TME
CRM plane on MRI
• mrT2 versus mrT3a <1mm spread
• Depth of T extramural spread
<5mm
• MRI detected lymph nodes
• MRI detected lymph nodes close to
the mesorectal fascia

40. MR CRM prediction for low rectal cancers:
TME plane safety
• MRI Low Rectal Stage 1: tumour on
MRI images appears confined to bowel
wall (intact muscularis propria of the
internal sphincter).
• MRI Low Rectal Stage 2: tumour on
MRI replaces the muscle coat but does
not extend into the intersphincteric
plane. Above sphincter it is confined to
the mesorectum.
• MRI Low Rectal Stage 3: invading
into the intersphincteric plane or lying
within 1mm of levator muscle above
the level of the sphincter complex.
• MRI Low Rectal Stage 4: invading the
external anal sphincter and infiltrating/
extending beyond the levators +/-
invading adjacent organ.

41. For tumors that are 5 cm or more
above the AV, the sphincter is
free
• When the tumor is 0-5 cm from
the AV, sphincter invasion needs
mention.
Tumor reaching upto internal
sphincter is T2 disease and can
be offered an inter-sphincteric
resection when not reaching the
inter-sphincteric space and when
at least 1 cm away from the AV
Tumors reaching upto or <1 cm
from AV require an APR.
Tumor invasion into
inter-sphincteric space (T2
disease) or external sphincter (T3
disease) and into levator ani
requires an extralevator APR after
NACT-RT to ensure negative
resection margins
Assessing Sphincter complex

42. Anatomic compartments beyond TME :
the exenterative compartments
from Dr Gina Brown

43. Assessment of Rectal Cancer:
how good quality MR imaging can help surgeons
• Is it malignant or not?
• What is the depth of invasion?
• Are lymph nodes involved? is there EMVI?
• Is the proposed excision plane safe?
Early Rectal Cancers
• EMR/ESD:
• TME
Rectal Cancer Staging for primary TME vs preop CRT TME
Low Rectal Cancer
• TME plane APE
• Beyond TME ELAPE
Locally Advanced Rectal Cancer
• Beyond TME/Exenteration

44. Evidence base for MRI as a
gold standard
• CRM involvement on MRI prognostic predictor for
recurrence
• Depth of extramural spread >5mm risk factor for poor
DFS
• Presence of MRI detected venous invasion – risk factor
for local and distant recurrence and seen more
frequently than path EMVI
• MRI detected mucinous tumours
• Tumour spread into or beyond the intersphincteric
plane: risk of local recurrence
• MRI TRG status: independent prognostic predictor for
overall survival and disease free survival and seen more
frequently than the pathologic gold standard of pCR

45. MRI findings that justify preoperative
chemo-radiation
CRM +ve or threatened
T3b tumors with >5 mm spread into perirectal fat
Sphincter complex involved
Extramesorectal nodes (MRI used to re-plan RT field)
T2 and T3 disease with bulky mesorectal nodes
Adjacent organ invasion (these are restaged after
NACT-RT to consider pelvic exenteration surgery)
Invasion of the anterior peritoneal reflection in upper
rectal cancers

47. Pre & Post CTRT
Post-treatment stage is indicated by the prefix “y.”
Accuracy of MRI for predicting yT stage is 50% and for CRM at restaging is 66%,

48. Pre & Post NACTRT

49. Restaging after CCRT/NACT-
RT
“Post-CCRT MR imaging has low
accuracy in predicting the
pathologic stage, with the major
component of error being
overstaging of pathologic stage T1
and T2 tumors; the overstaging is
due to the limited capability of MR
imaging to allow differentiation
between viable tumor, residual
fibrotic nontumor tissue, and
desmoplastic reaction. Understaging
of irradiated rectal cancer can affect
treatment planning, including the
surgical strategy, and thus affect the
tumor recurrence rate and patients’

51. Overstaging due to markedly hypointense tissue infiltration at the mesorectal fascia in a 65-
year-old man with rectal cancer. (a, b) Axial T2-weighted images obtained before CCRT (a
obtained at a lower level than b) show a hypointense mass in the rectum with involvement
of the mesorectal fascia (arrow). (c, d) On corresponding axial T2-weighted images obtained
after CCRT, the mass is markedly shrunken with low-signal-intensity tissue infiltration at
the mesorectal fascia (arrow). At surgery, there was no tumor invasion of the mesorectal
fascia.

52. CRC CE CT

53. Multi detector computed tomography (MDCT) scanning
protocol
120 kV, 200-250 mA, tube rotation time of 0.5 s per rotation (pitch 6); 16×0.75mm
collimation, table feed of 22.5mm per rotation and section thickness of 10 mm.
Prior to scanning, 40 ml of ionic contrast (Diatrizoate Sodium) diluted in 2 litres of
water -to drink over a period of 2.5 hours.
- 100ml of contrast medium (Iohexol 300 mg/ml) intravenously at a rate of 3
ml/s.using power injector
CT performed in the portal-venous phase with a 70 second delay between the start
of contrast material administration and the start of helical scanning. The 10 mm-
thick transverse CT images reconstructed at 2.5 mm intervals for interpretation of
MDCT data

54. The upper node (black arrow) depicts a typical metastatic node: the node shows no
contrast enhancement and remains hypo-intense except for an enhancing rim. The lower
node (white arrow) shows the typical features of a benign node: the node shows a hyper-
intense signal, comparable to that of enhancing vessels (V) and appears to have a relief. B
The metastatic node (black arrow) shows no apparent contrast enhancement
Gadofosveset-enhanced 3D T1-weighted gradient-echo images

55. MR Volumetry Although MR volumetry
sometimes results in
overestimation of the volume of
the remaining tumor after
CCRT, there is good correlation
of the tumor volume and
reduction after CCRT between
MR imaging and histopathologic
analysis. However, MR
volumetric evaluation cannot
demonstrate any differences
between patients with
complete histologic regression
and those with residual disease
Restaging of Rectal Cancer with MR Imaging after Concurrent Chemotherapy and Radiation Therapy
Dae Jung Kim, MD • Joo Hee Kim, MD • Joon Seok Lim, MD • Jeong-Sik Yu, MD Jae-Joon Chung, MD • Myeong-Jin Kim, MD • Ki Whang Kim, MD
RadioGraphics 2010; 30:503–516

56. PET CT

57. Primary Rectal Cancer Primary Colon Cancer
Staging –
MRI abdomen + pelvis with contrast
(to assess liver also)
If no outside/previous good quality
imaging
If NACT/RT not indicated- Xray Chest
If NACT/RT indicated or high risk
tumors-
CT Chest with Pre NACT/RT
Planning CT
If good quality outside imaging is
available- CT/MRI- the same will be
considered sufficient
Post NACT/RT assessment-
At the end of 5 weeks
Clinical assessment- p/r
MRI Pelvis Plain + USG abdomen
CECT abdomen + pelvis
For low risk patients
CXR
For high risk patients (High CEA/ bulky
tumor/nodal disease)
CT Chest
For patients with resectable
metastases/planned for morbid surgery
(eg pelvic exenteration)
PET CT to rule out disseminated disease

58. 3 Tesla MRI
High resolution
DWI (multiple B value
,IVIM)
DCE (T1 PERFUSION)
Fusion imaging
Subtraction
Parametric maps
Texture/Histogram

59. PET-MR
Multiparameteric PET-MR Assessment of Response to Neoadjuvant Chemoradiotherapy in Locally
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DOI: 10.4236/ami.2015.53005 2,536 Downloads 3,099 Views Citations
Author(s) Leave a comment
Ur Metser1*, Kartik S. Jhaveri1, Grainne Murphy1, Jaydeep Halankar1, Douglas Hussey1, Paul Dufort1, Erin Kennedy2

60. Radiogenomics

61. Thank You All