CT scangenerated frontal sinus templates in osteoplastic flap surgery

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CT scangenerated frontal sinus templates in osteoplastic flap surgery

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Caldwell radiograph from 6ft, positioned over FS. Composite CT image of frontal sinus (Fewins 04) Controlled burr holes along proposed osteotomy line (or within FS ... – PowerPoint PPT presentation

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Title: CT scangenerated frontal sinus templates in osteoplastic flap surgery

1
CT scan-generated frontal sinus templates in
osteoplastic flap surgery
British Rhinological Society May 2008

Mat Daniel, Jason Watson , Anshul Sama
Otorhinolaryngology and Maxillofacial Surgery
Nottingham University Hospital

2
Frontal sinus mapping inosteoplastic flap surgery

Crucially important in FS osteoplastic flap
surgery
Caldwell radiograph from 6ft, positioned over FS
Composite CT image of frontal sinus (Fewins 04)
Controlled burr holes along proposed osteotomy
line (or within FS area), connected with
oscillating drill (Maniglia 91)
Sinus probing
Transillumination
Image Guidance Systems (IGS)

3
Frontal sinus mapping

IGS more accurate than Caldwell, sinus probing,
or transillumination (Ansari 03, Melroy 06)
IGS reduces complications (Sindwani 04)
IGS may not be available, and does not give
actual 3D representation
In contrast, most ENT units will have links with
a maxillofacial laboratory

4
Aim

Develop a 3D template of the frontal sinus
that can be used intra-operatively as an
onlay guide to FS mapping

5
Model Template production

Import CT images,
identify required region

Print 3D sinus model layer by layer
Onlay malleable light-cure resin sheet and process
Drill FS on light-cure sheet to form custom
template
Sterilise for direct use in theatre
6
Clinical use

Close collaboration with prosthetics /
maxillofacial laboratory
Original model available in theatre
Onlay template sterilised
Template placed onto FS after skin flap
Glabella/ nasion/ supraorbital ridge
configuration used to anchor template for correct
placement
Outline of FS marked with a drill

7
Computerised 3D reconstruction
8
Model
9
Model template
10
Template in theatre
11
FS outlined
12
FS opened
13
Our experience

8 patients to date
Consistently accurate to within lt1mm of actual
frontal sinus size
Problem in chronic infection and with multiple
previous procedures, bone may be difficult to
differentiate from FS contents on CT, impacting
on quality of model and thus template

Advantages
CostltIGS model 100/20, template 25
Maxfac lab at most regional hospitals
Better anchoring than X ray
3D onlay template
3D model

Disadvantages Pre op planning Need specialist
facility Construction time (1 week) More
expensive than Caldwell X ray ?Accuracy
comparison with IGS further research
15
Conclusion

3D models of frontal area generated from CT scans
can be utilised to create 3D templates of the
frontal sinus, which are then used intra-op as an
onlay guide to frontal sinus mapping.
Early experience shows them to be consistently
accurate to within 1mm, suggesting they would be
a useful adjunct to current techniques, esp if
IGS not available.
Comparison with existing techniques is needed.

16
Thank you

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