1. MRI: techniques for rectal cancer staging and standardisation
Gina Brown
Department of Radiology
Royal Marsden Hospital
Imperial College, London

2. High resolution parameters
Phillips/Siemens 1.5T
GE 1.5 T TR
5000
3025 TE
100 85
no of slices 20 25
slice thickness/gap
3 /0 .3
3 /0
interleaved
ye s
echo train length 16 8
matrix
256 x256
256 x 256
phase encoding
inferosuperior for oblique
direction
coronal
anteroposterior fo oblique
axial
no of acquisitions 6 4
flow compensation no
saturation bands
anterior and superior
sequence
Turbo Spin-echo
FRFSE-XL
NPW/ SCIC/ TRF/fast/
options
no phase wrap
ZIP512
scan duration
7 mins
5 to 7 minutes

3. Sagittal T2w TSE FOV 250 RFOV 100% 24 slices 3/.0.4mm
Foldover direction AP
2 rest slabs anterior & superior
TSE factor 23
TE 125
TR 3961
Matrix 320/512r
Scan % 100
NSA 4
Scan length 6mins

4. 1. Ensure scans are T2 weighted high resolution
field of view and matrix parameters should not exceed a pixel size of 0.6mm x 0.6mm
Either 200mm x 200mm with 384 x 384 matrix
Or 60mm x 160mm with a 256 x 256 matrix
pixel size in mm = field of view/matrix
voxel size mm3 = pixel size x slice thickness

5. High res vs non high res High res –showing Early T2 tumour
the difference between a high resolution and suboptimal MRI scan. The difference in technique can make a subtantial but entirely preventable difference to staging accuracy.
High res –showing
Early T2 tumour
Non-High res
Same patient – T stage?

6. 2. Ensure planes are correct
Phased array Coil positioning critical
High Res Axials perpendicular to rectal wall
Coronal imaging parallel to anal canal
Don’t forget nodes
Brown et al BJR 2005

7. Correct Scan planes
Scans should be obtained perpendicular to the rectal wall, the sagittal MRI scans are used to plan the oblique axial images
Coronal images should be undertaken parallel to the anal canal to visualise the distal anorectum and distal mesorectal plane
High resolution coverage should include at least 5cm above the top of the tumour and to the L5/S1 level for all tumours to ensure that discontinuous tumour deposits are visualised

9. 3. Use of Sat Bands and firm abdominal compression to limit abdominal wall motion
The use of anterior and superior saturation bands reduce image degradation due to abdominal wall motion and  hyoscine butylbromide given as an i.m. injection or oral mebeverine reduces small bowel peristalsis respectively
Without Sat Bands
With Sat Bands

10. Reduction of physiological motion
Good lower abdominal compression esp in thin patients
Use of saturation bands / REST Slabs
If phase AP
Swap Phase direction R-L

11. Empty bladder
Use of anti-spasmodics

12. Peristalsis – use of antispasmodics

13. 4. Correct Coil Position
The surface phased array coil should be placed correctly over the lower pelvis. For low rectal cancers the distal edge of the coil should lie 10cm below the symphysis pubis to ensure that the distal rectum is in the centre of the image

14. 5. Other Sequences?
T1 weighted imaging, contrast enhanced imaging and fat saturated sequences do not contribute and worsen staging accuracy and should not be used for primary rectal cancer staging.
Caution when using diffusion weighted imaging for rectal cancer as it does not improve accuracy when compared with high resolution MRI techniques.
The prolonged examination time caused by additional non-contributory sequences reduce the overall quality of the examination as well as prolonging patient discomfort.

15. DWI has insufficient resolution to distinguish tumour from fibrosisа с d

16. Fat Saturation and Contrast Enhancement Does not improve accuracy
Tumour and normal anatomy both enhance and are not distinguished

17. MDT choices and making best use of high resolution MRI
Local excision
EMS /TEMS pre/post operative CRT MRI surveillance…
MRI T1/T2 Nx
MRI based
Selection
of patients
For range
treatments
MRI T3a/T3b N any
Low rectal stage 1/2
Primary TME Surgery: open v laparoscopic
MRI T3c/T3d N any
EMVI positive CRM safe
Biological agents and neoadjuvant
chemotherapy for MRI EMVI
Chemoradiotherapy
Restage:
Timing of
surgery
after CRT
6 vs 12?
Further Therapy
/Extended surgery
for mrCRM/low rectal
potential CRM unsafe
MRI Low rectal
Stage 3 or 4
Post CRT
yMRI TRG 1-2
MRI and PET surveillance
Deferral of surgery

18. Reporting Minimum Standards

19. Reporting Template Post Treatment

20. 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
Buscopan
Saturation Bands
Firm coil placement with secure abdominal compression

21. Key Bioimaging markers for poor outcome at baseline and post CRT
CRM involvement on MRI
Depth of extramural spread >5mm
Presence of MRI detected venous invasion
MRI detected mucinous tumours
Tumour spread into or beyond the intersphincteric plane
MRI TRG status

22. 10th – 11th March 2016, London, UK Intensive Hands On 2 Day Workshop
To receive further details
10th – 11th March 2016, London, UK
Intensive Hands On 2 Day Workshop
How to perform Rectal MRI staging and restaging accurately and consistently
HANDS ON Workstation PRACTICE Cases
Case Discussions
Tips and tricks for : Reporting and MDT based working