1. Implementing Fast T2 brain MRI as a substitute for CT head in follow-up shunted hydrocephalus or extra-axial collections
Presenter: Guilherme Cassia
C.Saint-Martin, G.Cassia, J.Atkinson, JP.Farmer
The Montreal Children’s Hospital
Montreal, Quebec, Canada
Chicago, November 2012

2. Disclosure
Nothing to disclose

3. Background CT - modality of choice
2005, Ashley Jr. et al. - 67% at least 3 CT’s
- 3% more than 50
- estimated 4 CT’s per year
Head CT has generally been the modality of choice to assess catheter placement and to identify shunt malfunction in pediatric patients with shunted hydrocephalus or extra-axial collections or cysts.

4. Background CT - modality of choice
childhood radiation exposure from CT scans might almost triple the risk of leukemia and brain cancer
Head CT has generally been the modality of choice to assess catheter placement and to identify shunt malfunction in pediatric patients with shunted hydrocephalus or extra-axial collections or cysts.

5. Background Low dose CT (80-100 mA) ~ 30% reduction DLP
I think we can put slides 3 and4 together with animation and appearance of the slide 4 content below the slide3 content
“Low dose Ct” could be commented in reference to normal CT regarding the mean dose. For example patient had CT regular with DLP 446,40 on Oct , had CT low dose with DLP 272,23on October for follow-up with respective CTDIVol of 56,06 and 36,21mGy. Wheni copmaredfew other patinets, I canestimated grossly the decreased in dose by 1/3 between regular and low dose CT.

6. Background Why not MR? Limitations of MR - long acquisition times
- need for sedation
- decreased catheter delineation
- less availability
I think we can put slides 3 and4 together with animation and appearance of the slide 4 content below the slide3 content
“Low dose Ct” could be commented in reference to normal CT regarding the mean dose. For example patient had CT regular with DLP 446,40 on Oct , had CT low dose with DLP 272,23on October for follow-up with respective CTDIVol of 56,06 and 36,21mGy. Wheni copmaredfew other patinets, I canestimated grossly the decreased in dose by 1/3 between regular and low dose CT. 6

7. Objective Offer an exam - No radiation - Fast - Ventricular system
- VP shunt tubes
- Extra-axial collections

8. Material and methods Fast Spin Echo T2 sequences
modified Matrix and Turbo Factor
< 1 minute
Axial
similar to CT plane (subjective comparison)
Coronal
bifrontal diameter (objective comparison)
cross section to better delineate the tube
best evaluation of extra-axial collections

9. Material and methods VacFix® (< 6 months)
- vacuum fixation cushions
Sedation
- chloral hydrate
- nembutal

10. Materials and Methods October 2010 to July 2012
69 children underwent 141 MRI instead of head CT
49 M:F 20
Indications for imaging
Newly inserted shunt tubing
Acute context with question of shunt dysfunction
Regular long term follow-up
I am not sure the mean age should be there, isn’t it already a result.
Reasons to image the brain were – newly inserted shunt tubing – acute context with query shunt dysfunction – regular follow-up.
We have to highlight the purposes of imaging because these are directly linked to the criteria of image quality and definition of Non Diagnostic exams

11. Purpose of imaging Ventricular size Position of shunt tubing
Extra-axial collections/cysts.

12. Material and Methods Perfect (P) (no motion artifact)
Acceptable (A) (motion artifacts, still diagnostic)
Non-diagnostic (ND) when answering one of the questions failed

13. Material and Methods Perfect (P) (no motion artifact)
Acceptable (A) (motion artifacts, still diagnostic)
Non-diagnostic (ND) when answering one of the questions failed

14. Material and Methods Perfect (P) (no motion artifact)
Acceptable (A) (motion artifacts, still diagnostic)
Non-diagnostic (ND) when answering one of the questions failed

15. Results Total non-diagnostic exams = 4 Axial T2 P A ND Total NS 64 37P A ND
Total NS 64 37 4
105 S 33 1 35
total 97 38 5
140
Cor T2  P A ND
Total NS 51 24 3 78 S 33 1 34
total 84 25
112
1) Image quality = Highlight the total number of failed exam : when both the axial and the coronal acquisitions were non-diagnostic=

16. Results Sedation < 5 years – 70% No sedation or natural sleep 0-6m
0-6m
6-12m
1-5y
> 5y
total
# of MRI 43 31 24
141 NS 36 21 25
106 CH 7 10 14
Nemb 4
2) Sedation rate = I will talk about sedation after the image quality ad before the duration analysis
Give also the corresponding proportion meaning more than 2/3 of the patients didn’t need sedation in the age group where they usually need sedation to undergo an MRI successfully.

17. Results Duration time < 15 min including:
positioning ( without or with pillow)
localizer and calibration
axial and coronal sequences ( 5-7 min)
If we have the results of the short assessment done by the tech, we should add these to this slide

18. Discussion Feasible Without specific training of the technologists
minor adaptations of MRI patient’s workflow
overall low sedation rate
excellent success rate
decrease in the annual background radiation

19. Discussion Limitations - Retrospective study
- No comparison with CT (gold standard)

20. Discussion Future developments
- cost : negotiate a specific billing code
- faster acquisitions
- assess 3T-3D + MPR vs. 1,5T 2 sequences
- apply 24/7/365

21. Conclusion Fast MRI acquisition is:
- fast (decreasing the need of sedation)
- non-radiating technique
- accurate to assess the ventricular system, extra- axial spaces and shunt tube
We can illustrate more, by adding few pictures on the slides of patients and methods and discussion

22. References
Pearce MS, Salotti JA, Little MP, McHugh K, Lee C, Kim KP, Howe NL, Ronckers CM, Rajaraman P, Sir Craft AW, Parker L, Berrington de González A.. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet Aug 4;380(9840): Epub 2012 Jun 7.
Ashley WW Jr, McKinstry RC, Leonard JR, Smyth MD, Lee BC, Park TS.. Use of rapid-sequence magnetic resonance imaging for the evaluation of hydrocephalus in children. J Neurosurg Aug;103(2 Suppl):
Miller JH, Walkiewicz T, Towbin RB, Curran JG.. Improved delineation of ventricular shunt catheters using fast steady-state gradient recalled-echo sequences in a rapid brain MR imaging protocol in nonsedated pediatric patients. AJNR Am J Neuroradiol Mar;31(3): Epub Nov 26.

23. Thank you!
We can illustrate more, by adding few pictures on the slides of patients and methods and discussion