1

Imaging theSkull

Reading Assignment

71-8787-89

Skull is Anatomically Complex

Use symmetryCreates problems 3D 2DDV & lateral views are typically inadequate for complete evaluation

2

Ancillary views necessary because of anatomic complexity

Nasal passageMaxillaMandibleFrontal SinusTympanic BullaTemporomandibular Joint

Nasal Passage/Maxilla

Han & Hurd. Practical Guide to Diagnostic Imaging, American

Veterinary Publications

Nasal Passage

Film must be paper-wrapped…conventional

cassette cannot be positioned adequately

Han & Hurd. Practical Guide to Diagnostic Imaging, American

Veterinary Publications

3

Frontal Sinuses

Han & Hurd. Practical Guide to Diagnostic Imaging, American

Veterinary Publications

Tympanic Bullae

Han & Hurd. Practical Guide to Diagnostic Imaging, American

Veterinary Publications

TMJ

Han & Hurd. Practical Guide to Diagnostic Imaging, American

Veterinary Publications

4

Teeth

Equine Skull RadiographyImaged standingVD/DV difficult to acquireAnatomy even more complex than in the dog

Skull Radiography in Perspective

Largely replaced by CT and MR imagingWhy

Reduces complexityTomographic aspect valuableContrast resolution

5

Uses of RadiographyOtitis mediaMandibular and maxillary tumorsSinusitisNasal cancerRhinitisDental disease

Otitis MediaCommon in dog and catUncommon in horseRadiographs not sensitive

Positioning problemsContrast resolution

SignsIncreased opacityWall thickening

6

Otitis Media?

Can’t tell from this

radiograph

11457345714

Otitis Externa Otitis Externa & Media

CT is much more accurate for detecting otitis media

110473

Tympanic bulla

expansion due to chronic

otitismedia

7

119499

Otitis media with stylohyoidhyperostosis in a horse

Mandibular/Maxillary tumors

Much more common in small animals than horsesRadiography will “understage”diseaseThese tumors will have radiographic signs of an aggressive bone disease

66408

Note aggressive

primarily lytic aggressive

lesion

8

111963

Osteosarcoma of zygomaticarch is better seen in the CT

images

SinusitisRare in small animals as isolated problemMore common in horses

Secondary to tooth root abscessesFluid accumulation

Standing position helpful to detect fluid line

Bone changes unusual

63368114128

Normal Maxillary sinus fluid with fluid lines

9

63368

Conspicuous fluid lines

112029

Maxillary fluid seen

In the CT, fluid is seen but sinus mucosal lining is also thick

CT image is inverted from acquisition position so fluid is on

“top” of the sinus gas.

10

Nasal CancerCommon in dogs

Less common in catsRare in Horses

Increased opacitySecondary sinusitis common

Turbinate destructionRadiographs will underestimate the extent of the process

One month later

Nasal adenocarcinoma

Normal radiograph

Nasal adenocarcinomawith increased

opacity and bone destruction

11

113804

CT provides superior staging

Reformatting valuable in staging

disease…intracranial extension seen here

113804

VA002357113804

MR can distinguish between tumor and exudate; this is impossible in radiographs. Exudate has more

signal than tumor in the MR image on the left

12

T2 T1+C

T1+CT1+C

MR is also more specific for detecting intracranialextension

NC4348

111105

Aggressive nasal tumor in a horseNasal Lymphoma in a Horse

Nasal Lymphoma in

a Horse

13

Nasal Lymphoma in a Horse

2005.06.29Equine nasal lymphoma successfully treated with

radiation

2005.12.15

14

RhinitisNot commonAspirgillosis in dogs

Can have increased nasal opacity, but punctate destructive changes are typical.

Rare in horses except in combination with sinusitis

Punctate lysis characterizes

nasal aspergillosis

in dogs

64784

Closeupshowing punctate

lysis

15

CT shows extent of lysis

and non-tumor like

proliferativepattern

107762

Dental DiseaseCommon in small animals but radiography has limited roleSignificant problem in horses

Young vs. old horse tooth appearanceDeciduous vs. permanent teeth

73944

Canine mandibular tooth root abscess

16

1082062 years

Periapical radiolucent regions normal in

young horsesNote “caps”

1082063 years

Retained deciduous tooth “cap”

11227312 years

With ageing, roots occupy less of mandible

17

114671

Mandibular tooth root abscess with fractured root

113162

Maxillary PM2 root abscess; more caudal root abscesses result in maxillary sinusitis