MRI: techniques for rectal cancer staging and standardisation - PowerPoint Presentation

Slide1

MRI: techniques for rectal cancer staging and standardisation

Gina BrownDepartment of RadiologyRoyal Marsden HospitalImperial College, London

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

ye s

echo train length

16

8

matrix

256 x256

256 x 256

phase encoding

inferosuperior for oblique

inferosuperior for oblique

direction

coronal

coronal

phase encoding

anteroposterior fo oblique

anteroposterior fo oblique

direction

axial

axial

no of acquisitions

6

4

flow compensation

no

no

saturation bands

anterior and superior

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

Sagittal T2w TSE

FOV 250 RFOV 100%24 slices

3/.0.4mm

Foldover

direction AP

2 rest slabs anterior & superior

TSE factor 23TE 125TR 3961Matrix 320/512rScan % 100NSA 4Scan length 6mins

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 matrixpixel size in mm = field of view/matrixvoxel size mm3 = pixel size x slice thickness

High res vs non high res

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?

2. Ensure planes are correct

Phased array Coil positioning criticalHigh Res Axials perpendicular to rectal wallCoronal imaging parallel to anal canalDon’t forget nodes

Brown et al BJR 2005

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

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

Reduction of physiological motion

Good lower abdominal compression esp in thin patientsUse of saturation bands / REST Slabs

If phase AP

Swap Phase direction R-L

Empty bladder

Use of anti-

spasmodics

Peristalsis – use of antispasmodics

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

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.

DWI has insufficient resolution to distinguish tumour from fibrosis

b

а

с

d

Fat Saturation and Contrast Enhancement Does not improve accuracy

Tumour and normal anatomy both

enhance and are not distinguished

MDT choices and making best use of high resolution MRI

MRI based Selection

of patients

For range

treatments

Local excision

MRI and PET surveillanceDeferral of surgeryChemoradiotherapy

Restage:

Timing of

surgery

after CRT

6 vs 12?

Biological agents and neoadjuvant

chemotherapy for MRI EMVI

Further Therapy

/Extended surgery

for mrCRM/low rectal

MRI T1/T2 Nx

EMS /TEMS

pre/post operative CRT

MRI surveillance…

MRI Low rectal

Stage 3 or 4

Post CRT

yMRI

TRG 1-2

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

potential CRM unsafe

Reporting Minimum Standards

Reporting Template Post Treatment

Technique Summary of Essentials

Scan duration = quality 7mins average length of each sequence4-6 NSA/NEX and T2- FSE / TSE /FRFSE0.6mm x 0.6mm x 3mm = 1.1mm3 voxelAdequate coverage – 5cm above top of tumourPerpendicular to the rectal wallLow rectal cancer – parallel to anal canalEnsure discontinuous deposits are covered on high resBuscopan

Saturation Bands

Firm coil placement with secure abdominal compression

Key Bioimaging

markers for poor outcome at baseline and post CRTCRM involvement on MRIDepth of extramural spread >5mm

Presence of MRI detected venous

invasion

MRI detected

mucinous

tumoursTumour spread into or beyond the intersphincteric planeMRI TRG status

10

th

– 11

th

March 2016, London, UK

Intensive Hands On 2 Day

W

orkshop

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

Email:

Gina.Brown@rmh.nhs.uk

To receive further details