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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
Atlas of Small Animal CT & MRI is a highly illustrated diagnostic imaging guide to common clinical disorders of dogs and cats. * Contains over 3,000 high quality CT, MRI and related diagnostic images * Offers a unique approach emphasizing comparative imaging and pathologic correlation * Focuses on important imaging features relevant to imaging diagnosis of disease in dogs and cats * Written by internationally renowned experts in the field
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Veröffentlichungsjahr: 2015
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CONTENTS
Cover
Title page
Preface
Abbreviations
How to use this Atlas
Section 1: Head & Neck
1.1 Nasal cavity and paranasal sinuses
Normal anatomy
Normal nasal cycle
Developmental disorders
Inflammatory disorders
Neoplasia
References
1.2 Ear
Normal ear
Inflammatory disorders
Neoplasia
Degenerative disorders
References
1.3 Temporomandibular joint
Normal temporomandibular joint
Developmental disorders
Trauma
Inflammatory disorders
Neoplasia
Degenerative disorders
References
1.4 Skull
Introduction
Developmental disorders
Trauma
Inflammatory disorders
Neoplasia
References
1.5 Orbit
Introduction
Developmental disorders
Trauma
Inflammatory disorders
Neoplasia
References
1.6 Globe
Introduction
Trauma
Inflammatory disorders
Neoplasia
Degenerative disorders
References
1.7 Salivary glands
Introduction
Inflammatory disorders
Neoplasia
Sialolithiasis and sialocele
References
1.8 Lymph nodes
Introduction
Inflammatory disorders
Neoplasia
References
1.9 Oral cavity
Introduction
Developmental disorders
Trauma
Inflammatory disorders
Odontogenic neoplasia
Oral cavity neoplasia
References
1.10 Larynx, pharynx, and neck
Introduction
Developmental disorders
Trauma
Inflammatory disorders
Neoplasia
Idiopathic and other disorders
References
1.11 Thyroid and parathyroid
Normal thyroid and parathyroid
Hypothyroidism
Thyroid neoplasia
Parathyroid nodules
References
Section 2: Brain
2.1 Ventricular system and hydrocephalus
Normal ventricular system
Hydrocephalus
Congenital hydrocephalus
Obstructive hydrocephalus
Communicating (nonobstructive) hydrocephalus
References
2.2 Brain edema
Introduction
Cytotoxic edema
Vasogenic edema
Interstitial or hydrocephalic edema
Osmotic edema
References
2.3 Developmental disorders
Anomalous development of the brain
Hindbrain herniations and malformations
Diverticulation and cleavage disorders
Malformations of cortical development
Nonneoplastic cysts
References
2.4 Trauma, hemorrhage, and vascular disorders
Head trauma
Staging hemorrhage
Extraaxial hemorrhage
Brain contusion and hemorrhage
Vascular disorders
References
2.5 Metabolic, toxic, and degenerative disorders
Inherited metabolic disorders
Acquired metabolic disorders
Toxic disorders
Degenerative disorders
References
2.6 Noninfectious inflammatory disorders
Granulomatous meningoencephalitis
Necrotizing encephalitis
References
2.7 Infectious inflammatory disorders
Viral encephalitis
Bacterial meningoencephalopathy
Mycotic meningoencephalitis
Protozoal meningoencephalitis
Helminth-induced meningoencephalopathy
References
2.8 Neoplasia
Neoplasms of the meninges
Neoplasms of neuroepithelial origin
Lymphoma and hematopoietic neoplasms
Metastatic neoplasms
References
2.9 Sella and parasellar region
Normal pituitary gland
Dynamic CT and MR protocols
Empty sella syndrome
Pituitary cysts
Pituitary hemorrhage/pituitary apoplexy
Hypophysitis
Neoplasia
References
2.10 Cranial nerves
Cranial nerves
Inflammatory and idiopathic disorders
Neoplasia
Cavernous sinus syndrome
References
Section 3: Vertebral Column & Spinal Cord
3.1 Developmental disorders
Anomalies of the vertebral column
Intradural arachnoid diverticula
Spinal neural tube defects (spinal dysraphism)
Vascular anomalies
References
3.2 Traumatic and vascular disorders
Vertebral column trauma
Traumatic intervertebral disk extrusion
Spinal cord trauma
Vascular disorders
References
3.3 Inflammatory disorders
Noninfectious inflammatory disorders
Infectious inflammatory disorders
References
3.4 Neoplasia
Extradural neoplasia
Intradural–extramedullary neoplasia
Intramedullary neoplasia
References
3.5 Intervertebral disk disease and other degenerative disorders
Intervertebral disk disease
Other degenerative disorders of the spine
Extrinsic cysts
References
3.6 Brachial and lumbosacral plexus
Normal anatomy of the brachial and lumbosacral plexus
Muscle denervation
Trauma
Inflammatory disorders
Neoplasia
References
Section 4: Thorax
4.1 Thoracic wall and diaphragm
Thoracic wall
Diaphragm
References
4.2 Pleural space
Normal pleural space
Pneumothorax
Pleural effusion
Pleural masses
Pleural thickening/fibrosis
References
4.3 Mediastinum and esophagus
Normal mediastinum and variants
Developmental disorders
Trauma
Inflammatory disorders
Mediastinal neoplasia
Esophagus
References
4.4 Heart, pulmonary vasculature, and great vessels
Pericardium
Heart
Pulmonary vasculature
Great vessels
References
4.5 Airways
Normal airways
Tracheal and bronchial developmental disorders
Trauma
Inflammatory disorders
Neoplasia
Degenerative disorders
References
4.6 Small airways and parenchyma
Introduction
Atelectasis
Developmental disorders
Pulmonary edema
Pulmonary contusion and hemorrhage
Lung lobe torsion
Inflammatory lung disorders
Neoplasia
Degenerative disorders
References
Section 5: Abdomen
5.1 Body wall, retroperitoneum, and peritoneal cavity
Trauma
Effusion
Inflammatory disorders
Neoplasia
References
5.2 Hepatovascular disorders
Introduction
Vascular disorders
References
5.3 Hepatobiliary disorders
Introduction
Trauma
Inflammatory disorders
Nodules and mass lesions
Degenerative and other disorders
Cholelithiasis and biliary obstruction
References
5.4 Gastrointestinal tract
Introduction
Mechanical obstruction, trauma, and hemorrhage
Inflammatory and vascular disorders
Neoplasia
References
5.5 Pancreas
Inflammatory disorders
Neoplasia
References
5.6 Adrenal gland
Vascular disorders
Neoplasia
Degenerative disorders
References
5.7 Spleen
Introduction
Trauma
Vascular disorders
Inflammatory disorders
Neoplasia
Degenerative disorders
References
5.8 Urinary tract
Introduction
Developmental disorders
Trauma
Vascular disorders
Inflammatory disorders
Neoplasia
Degenerative disorders
References
5.9 Reproductive tract
Introduction
Female reproductive tract
Male reproductive tract
References
Section 6: Musculoskeletal System
6.1 Developmental and metabolic disorders
Developmental disorders
Metabolic disorders
References
6.2 Trauma
Fracture
Soft tissue trauma
Traumatic disorders of the shoulder and stifle joints
References
6.3 Inflammatory disorders
Inflammatory disorders of bone
Inflammatory disorders of joints
Inflammatory disorders of soft tissues
References
6.4 Neoplasia
Primary bone tumors
Malignant neoplasia of joints
Other malignant soft-tissue neoplasms
References
6.5 Degenerative disorders
Soft tissues
Joints
References
Index
End User License Agreement
List of Tables
Chapter 2.2
Table 2.2.1 Distribution and causes of brain edema.
Chapter 2.4
Table 2.4.1 MR staging of intracranial hemorrhage.
Chapter 5.2
Table 5.2.1 Protocols for CT angiography. Choose whether to perform a single-phase or dual-phase protocol. The most thinly collimated images are appropriate for very small dogs (<10 kg) and multislice scanners. Timing is determined from the dynamic CT scan by creating a graph with regions of interest, or by counting the number of images (at 1 slice/second) until peak vessel enhancement. TA = time to peak contrast in aorta (s), TAPS = total time of arterial phase scan (s), Delay = time delay between arterial and portal phase scans. Pre-delay (TA) and interscan delay (Delay) are programmed into the dual-phase scan at setup. The portal phase scan should begin at plateau of portal enhancement, which can be estimated at 20–30 seconds depending on body weight, with moderate individual variability. Contrast medium used should be non-ionic and high concentration.
List of Illustrations
How to use this Atlas
Figure 2.8.23
High-grade Oligodendroglioma (Canine) CT & MR
5y French Bulldog with progressive neurologic signs referable to intracranial disease. There is an irregularly shaped, heterogeneously enhancing, bi-hemispheric mass evident on contrast-enhanced CT (
a
) and T1 MR (
b
) images. Post-mortem examination confirmed grade III oligodendroglioma (
c
).
Chapter 1.1
Figure 1.1.1
Normal Nasal Cavity (Canine) CT
2y MC Great Pyrenees mix. Representative transverse plane images of the nasal passages and paranasal sinuses ordered from rostral to caudal (
a–f
). Representative dorsal plane images ordered from dorsal to ventral (
g–i
). The dorsal (
a
: small white arrow) and ventral (
a
: large white arrow) nasal conchae are finely scrolled rostrally and become larger caudally as the ethmoidal conchae or ethmoturbinates (
c
: open arrow). The nasal septum (
a
: arrowhead) separates the left and right nasal cavities. The dorsal, middle, and ventral nasal meati (
a:
black arrows) allow airflow to the caudal nasal cavity. The nasal sinuses include the maxillary recess (
c
: asterisk), the frontal sinus (
e
: large open arrow), and the sphenoidal sinus (
e
: small open arrow). The nasopharyngeal meatus (
c
: black arrow) connects the nasal cavity to the pharynx. The cribriform plate (
e,h
: arrowheads) separates the nasal cavity from the calvarium.
Figure 1.1.2
Normal Nasal Cavity (Canine) MR
MR images of the nose provide good detail of the nasal turbinates. Normal turbinates are scrolled and symmetrical. They appear moderately intense on T1 images (
a
) and hyperintense on T2 (
c
), PD (
d
), and T1 contrast-enhanced (
b
) images.
Figure 1.1.3
Normal Nasal Cycle (Canine) CT
Typical appearance of normal ectoturbinates in the midnasal cavity (
a
). The nasal cycle results in turbinate asymmetry due to nonuniform mucosal perfusion (
b
). This is a normal physiologic phenomenon that is thought to accelerate the rate of nasal mucosal healing from minor injury due to nasal airflow. The nasal cycle has a periodicity of 2–3 hours in dogs.
Figure 1.1.4
Nasopharyngeal Stenosis (Canine) CT
1y F Italian Greyhound with chronic nasal discharge. There is focal occlusion of the nasopharyngeal lumen near the level of the pterygoid processes and 1 cm caudal to the caudal margin of the hard palate (
b,d
: arrow). The pharyngeal lumen rostral and caudal to this focal lesion appears normal (
a,c
: arrow). The soft tissues associated with the occlusive lesion mildly contrast enhance (
b
). Nasopharyngeal stenosis was confirmed rhinoscopically, and biopsy revealed moderate chronic active neutrophilic, eosinophilic, and lymphoplasmacytic pharyngitis and rhinitis.
Figure 1.1.5
Foreign Body Rhinitis—Plant Awn (Canine) CT
9y FS Labrador Retriever. The transverse plane image reveals unilateral regional nasal turbinate destruction. The fluid-attenuating mass represents a combination of remaining turbinates, mucosa, and accumulated exudate. The fragmented gas pattern suggests this is not a solid mass. A plant awn (foxtail foreign body) was removed at the time of rhinoscopy. Plant awns are usually not detected on CT or MRI, although the focal or regional inflammatory response is characteristic.
Figure 1.1.6
Foreign Body Rhinitis—Tooth Fragment (Feline) CT
16y MC Domestic Longhair with chronic right-sided nasal discharge, chronic renal failure, and multiple missing teeth (
a,c
). An irregularly margined mineral-attenuating mass is present in the rostral aspect of the right nasal cavity. This is associated with adjacent turbinate destruction and increased soft-tissue opacity, consistent with mucosal proliferation and exudates. There is also distortion of the right maxillary bone (
a
: arrow) that likely results from chronic rhinitis and concurrent metabolic bone disease due to chronic renal failure. Resorption of the right maxillary bone (
a
: arrow) and the hard palate caudal to the mass is also evident (
b
: arrow). The mineral opacity was a retained migrated tooth root with peripheral cementum proliferation. This cat also has many missing teeth, pronounced periodontal bone resorption, and proliferative bone remodeling seen with chronic dental disease (
a
: arrowheads).
Figure 1.1.7
Wood Foreign Body (Canine) CT
5y FS Australian Shepherd with reverse sneezing and respiratory distress. On unenhanced images, there is hyperattenuating material in the right caudal nasopharynx surrounded by soft tissue (
a
: arrow). On contrast-enhanced images, the soft tissue surrounding the foreign material is strongly enhancing (
b
), representing inflammation and granulomatous tissue. The material extends into the soft palate, which appears as a hyperattenuating structure (
c
). Endoscopy revealed a wood foreign body (stick) in the caudal nasopharynx (
d
). The stick was removed via endoscopy.
Figure 1.1.8
Lymphocytic Plasmacytic Rhinitis and Sinusitis (Canine) CT
9y MC Australian Shepherd Dog with chronic bilateral nasal discharge. These are representative images of the sinonasal region from rostral to caudal. The normal turbinate pattern is partially obscured by mucosal proliferation and accumulated exudates. These findings are most pronounced rostrally and in the left ventral meatus. Although partially obscured by the increased fluid-opacity in the nasal cavity, there is evidence of nonuniform turbinate atrophy, which was confirmed with rhinoscopy. A small volume of dependent exudate is also seen in the ventral aspect of the right frontal sinus (
d
: arrow). Nasal biopsy revealed chronic lymphocytic plasmocytic neutrophilic rhinitis.
Figure 1.1.9
Eosinophilic Rhinitis and Sinusitis (Canine) CT
12y FS Australian Cattle Dog with a 5-year history of cough and mucopurulent nasal discharge. Images
a–c
are unenhanced, and images
d–f
are corresponding contrast-enhanced images. Images
g
and
h
are representative images of the cribriform plate and adjacent anatomy. There is soft-tissue opacification of the nasal cavity and frontal sinuses that heterogeneously contrast enhances. Marked bilateral turbinate destruction is seen with linear bony turbinate remnants evident in the mid-nasal cavity, best seen in image
b
. Multiple focal regions of cortical osteolysis are evident in bones comprising the sinonasal margins (
b
,
c
: arrows), and there is diffuse periosteal reaction involving the frontal bones. A biopsy acquired at the time of rhinoscopy revealed chronic eosinophilic, mastocytic inflammation consistent with allergic rhinitis. This is an unusually aggressive appearance for an immune-mediated rhinosinusitis. Although some features, such as the presence of cortical bone destruction and ill-defined mass effect, are consistent with neoplasia, the diffuse distribution of the soft tissue and bone destructive lesions and the persistence of some residual turbinate architecture are more indicative of inflammatory disease. The dog improved with medical management and had mild persisting signs referable to chronic nasal disease 2 years after the initial CT study was performed.
Figure 1.1.10
Suppurative Rhinitis—Inflammatory Nasal Polyp (Feline) CT
13y MC Domestic Shorthair with a malodorous, brown mucoid left-sided nasal discharge. Multiple dental extractions had been performed 1 month prior to the CT scan. Multiple teeth are missing, and there is osteolysis of residual alveolar bone. Soft-tissue opacity is present within the left ventral nasal cavity and adjacent left maxillary canine alveolar cavity (
a
: asterisk). A pedunculated nasopharyngeal mass arises from the left nasal cavity (
b
,
c
: arrow). The full extent of the mass is appreciated in
c
, which includes a dorsal plane view of the nasopharynx. The polyp was excised at the time of rhinoscopy (
d
: asterisk). Although not determined from these images, an oronasal fistula was also present at the site of the canine tooth extraction.
Figure 1.1.11
Ossifying Inflammatory Nasal Polyp (Canine) CT
13y MC Golden Retriever with left-sided epistaxis. A well-delineated, irregularly shaped mineralized mass is present in the left nasal cavity surrounded by uniform soft-tissue opacity (
a
). Nonuniform contrast enhancement of the nasal soft tissues suggests some preservation of the turbinates and overlying mucosa (
b
). The diameter of the left palatine foramen is increased (
a
: arrow), and the nasal septum is mildly deviated to the right. A well-demarcated mass was seen on rhinoscopic examination (
d
). Nasal biopsy revealed moderate diffuse chronic active rhinitis with reactive bone formation.
Figure 1.1.12
Oronasal Fistula (Canine) CT
6mo M Australian Shepherd with an oronasal fistula resulting from a bite injury at 1 week of age. Two attempts had been made to close the fistula. There is a large defect in the left palatine bone and maxilla seen on the transverse and 3D images (
b
: arrows). Multiple maxillary teeth are absent, and there is mild turbinate loss in the left nasal passage secondary to inflammation.
Figure 1.1.13
Oropharyngeal/Nasopharyngeal Fistula (Canine) CT
15y FS German Shepherd Dog mix with 2-year history of nasal discharge. There is a focal defect in the right palatine bone (
a
,
b
: arrow). There is complete loss of the nasal turbinates in the right rostral nasal cavity (
b
). The soft palate is intact on midline (
e
), but on the right of midline there is a defect in the soft palate that allows communication between the nasal cavity, nasopharynx, oral cavity, and oropharynx (
c
,
e
: open arrow).
Figure 1.1.14
Mycotic Rhinosinusitis and Osteomyelitis—Aspergillosis (Canine) CT
8y MC Rottweiler with chronic right-sided nasal discharge. Images
a–e
are ordered from rostral to caudal. There is nearly complete right-sided turbinate destruction/atrophy with additional regional left-sided ventral turbinate atrophy (
a–c
). Amorphous soft-tissue opacity is present further caudally in the right nasal cavity and in the right frontal sinus (
c–e
). The heterogeneous soft-tissue mass in the frontal sinus, which contains fragmented gas and focal mineral opacities (
e
: asterisk), is characteristic of a fungus ball. Erosive destruction of the right frontal bone (
e
: arrows) is also seen as a result of chronic inflammation. The constellation of CT imaging findings is consistent with chronic mycotic rhinitis from
Aspergillus
species. Rhinoscopic findings included the presence of marked nasal mucosal hyperemia and fungal plaques (
f
). Right-sided nasal biopsy revealed severe suppurative and lymphofollicular rhinitis with fungal plaques.
Figure 1.1.15
Mycotic Rhinosinusitis and Osteomyelitis—Aspergillosis (Canine) CT
11y MC Rottweiler with chronic left-sided mucopurulent and hemorrhagic nasal discharge. There is nasal turbinate atrophy with associated residual mucosal hypertrophy in the left nasal cavity (
a
,
e
,
f
: asterisk). The left frontal sinus contains a soft-tissue mass with entrapped fragmented gas (
c
: large arrow). A mixed pattern of frontal bone osteolysis and periosteal reactive productive response is also seen (
b–e
: arrowheads). A focal defect in the left dorsal cribriform plate is seen on both transverse and dorsal plane reformatted images (
c
,
d
: small arrow), and a second defect is suspected on the right side (
d
: open arrow), although there is no overt nasal disease adjacent to the cribriform plate on the right. Nasal biopsy confirmed a diagnosis of mycotic rhinosinusitis.
Figure 1.1.16
Mycotic Rhinosinusitis—Aspergillosis (Canine) CT & MR
14y MC Labrador Retriever with chronic left-sided nasal discharge. CT images were acquired at the time of initial evaluation. MR images were acquired approximately 2 months later. A large, focal defect is seen in the left frontal bone (
a
,
b
: large arrow). An adjacent irregularly margined soft-tissue mass is consistent with a fungus ball (
a
,
b
: small arrow). The bone defect is again seen on the subsequent MRI examination (
c–f
). Ill-defined contrast enhancement is seen within the defect, likely due to focal meningeal enhancement and possible left olfactory bulb invasion. A dorsal plane MR image shows a signal void within the left nasal cavity due to turbinate atrophy (
g
). Contrast-enhancing soft tissue in the caudal aspect of the nasal cavity likely represents hypertrophy of residual nasal mucosa. Nasal biopsy and fungal culture confirmed a diagnosis of mycotic rhinosinusitis due to
Aspergillus
species.
Figure 1.1.17
Cryptococcosis (Feline) CT
15y M Domestic Shorthair with stertor, sneezing, and progressive open-mouth breathing. The left and right nasal passages are completely opacified with soft tissue material, but bony turbinates are largely preserved (
a
: arrows). The left and right maxillary recesses, the nasopharynx (
c
: open arrow), and the left frontal (
d
: black open arrow) and sphenopalatine (
d
: asterisk) sinuses are also completely opacified with soft-tissue or fluid attenuating material. The dorsal wall of the nasopharynx appears irregular and thickened (
d
: black arrow), and the nasopharyngeal lumen is narrowed. Rhinoscopy revealed polypoid pharyngeal mucosal inflammation (
e
), and
Cryptococcus neoformans
was cultured from the tissue.
Figure 1.1.18
Nasal Lymphoma (Feline) CT & MR
12y MC Domestic Shorthair with chronic bilateral serosanguinous nasal discharge. Paired unenhanced (
a–c
) and contrast-enhanced (
d–f
) CT images progressing from rostral to caudal were acquired at the time of initial diagnosis. Soft-tissue opacity fills the nasal cavity, and there is underlying predominantly right-sided turbinate destruction. A poorly defined, contrast-enhancing mass is present in the ventral nasal cavity and extends into the nasopharynx (
e
,
f
: asterisk). There is lateral displacement of the frontal and/or palatine bone forming the deep part of the right orbit due to intranasal tumor expansion (
b
: arrow). The cat was treated with chemotherapy, and signs resolved for approximately 1 year. MR images (
g–i
) were acquired approximately 1 year following the CT examination after a recent onset of intracranial signs. There is a large, mildly contrast-enhancing soft-tissue mass within the nasal cavity, which extends caudally to involve the frontal sinuses (
g–i
: asterisk). Destruction of nasal and maxillary bones has occurred with dorsal extension of the neoplasm resulting in facial deformity (
g
: arrowheads). The mass also breaches the cribriform plate caudally (
h
,
i
: arrow) and extends into the rostral aspect of the cranial vault with associated forebrain edema (
g
).
Figure 1.1.19
Nasal Lymphoma (Canine) CT
3y MC Rhodesian Ridgeback with a 3-month history of nasal discharge and stertor. There is a predominantly right-sided nasal mass that extends beyond midline to fill the ventral part of the left nasal cavity rostral to the maxillary sinuses. The mass extends caudally to the nasopharynx (
d
: asterisk). Nearly complete osteolysis of the right nasal ectoturbinates is evident (
a
,
b
), and there is destruction of the palatine portion of the maxilla and the palatine bone (
a
,
b
: arrow). Vomer bone destruction is also present where the mass extends across midline (
a
,
b
: arrowhead). Retrograde rhinoscopy revealed a nasopharyngeal mass (
e
).
Figure 1.1.20
Nasal Transitional Cell Carcinoma (Canine) CT
7y MC Golden Retriever cross with a 2-month history of right-sided epistaxis. A large soft-tissue mass fills the right nasal cavity and extends across midline (
a
). The right ectoturbinates are obliterated by the mass, and there is right maxillary and nasal septum destruction (
a
). Regional destruction of the right side of the cribriform plate is seen (
b
), and the right frontal sinus is filled with fluid-attenuating material. The nasal mass enhances heterogeneously and extends through the breach in the right maxillary bone (
c
: arrow). There is prominent meningeal enhancement adjacent to the right cribriform osteolytic region (
d
: large arrow) as well as an associated mild midline shift of the interolfactory longitudinal fissure (
d
: small arrow). Material within the right frontal sinus does not contrast enhance, confirming fluid and exudate entrapment from sinus obstruction. Nasal biopsy revealed transitional cell carcinoma.
Figure 1.1.21
Nasal Carcinoma (Canine) MR
12y FS Australian Shepherd with progressive stertor. Transverse images (
a–c
) are at the same anatomic level at the rostral extent of the cribriform plate. Representative dorsal plane images (
d–e
) are ordered from dorsal to ventral. A large mass of mixed-signal intensity fills the right nasal cavity, obliterating the right ecto- and endoturbinates. Cribriform bone margins are ill-defined or absent and indicative of destruction (
b
,
e–g
: arrow). There is right olfactory and frontal lobe T2 hyperintensity associated with the breach of the cribriform plate and intracranial extension of the contrast-enhancing mass (
h
: arrows). Right frontal obstructive sinusitis is also present (
a–c
,
g
).
Figure 1.1.22
Nasal Anaplastic Adenocarcinoma (Canine) CT
13y MC Schnauzer with trismus and temporal muscle atrophy. Representative CT images include unenhanced (
a
,
c
,
e
,
g
) and corresponding contrast-enhanced (
b
,
d
,
f
,
h
) images. A highly aggressive mass extends from the ethmoid bone to the retropharyngeal region. Mass margins are ill defined on the contrast-enhanced images with enhancement extending along fascial planes and invading temporal and pterygoid musculature. Marked destruction of ethmoid, frontal, palatine, pterygoid, and sphenoid bones is evident, and the mass extends into the cranial vault. Cytologic evaluation revealed aggressive, anaplastic adenocarcinoma.
Figure 1.1.23
Nasal Chondrosarcoma (Canine) CT
6y FS Labrador Retriever cross with chronic epistaxis. Representative unenhanced (
a–c
) and corresponding contrast-enhanced (
d–f
) transverse images are ordered from rostral to caudal. Representative dorsal plane images are ordered from dorsal to ventral. A partially mineralized soft-tissue mass fills the left nasal cavity (
a–c
). Extensive turbinate destruction has occurred, but foci of amorphous intralesional mineralization are evident (
a
,
c
: arrow). The mass contrast enhances heterogeneously (
d–f
), and the mineralized foci are accentuated in the narrowly windowed enhanced images. The cribriform plate is intact (
g–i
). Nasal biopsy confirmed a diagnosis of chondrosarcoma.
Figure 1.1.24
Nasal Osteosarcoma (Canine) CT
11y FS Rottweiler with a 3-month history of sneezing and epistaxis. Representative transverse images are all at the same anatomic level in the midnasal cavity. Images
a
and
b
are the same image presented in a wide and a narrow window, respectively. A partially mineralized soft-tissue mass fills the left nasal cavity, with the extent of mineralization best seen in the narrowly windowed image (
b
: arrows). There is also associated destruction of the hard palate (
a
: large arrow) and productive reactivity of the maxilla (
a
: small arrows). The mass heterogeneously contrast enhances. A nasal biopsy confirmed a highly aggressive and infiltrative osteosarcoma.
Figure 1.1.25
Osteochondrosarcoma (Canine) CT
5y MC Labrador Retriever with nasal discharge and stertor. There is a smoothly margined mineralized mass occupying the midnasal cavity. This mass extends ventrally through a bony defect at the rostral aspect of the palatine bone, and there is associated destruction of the nasal septum (
b
: arrow). Moderate fluid accumulation in the caudal nasal cavity and the left frontal sinus is also evident (
c
). This mass has the stippled, granular imaging features characteristic of multilobular osteochondrosarcoma. Although these neoplasms most commonly originate from flat bones comprising the calvarium, they have also been reported to arise from the hard palate.
Figure 1.1.26
Nasal Mast Cell Tumor (Canine) CT & MR
8y FS Labrador Retriever with a rostral nasal mass. A well-defined ovoid mass is located adjacent to the right nares (
a–c
). The mass is soft-tissue attenuating on the CT image (
d
) and moderately T1 hyperintense (
b
) and markedly T2 hyperintense (
e
) on MR images. The T2 hyperintensity extends beyond the mass margins, indicating the presence of perilesional edema. The mass is only mildly contrast enhancing, which slightly diminishes lesion conspicuity because of the degree of enhancement of adjacent normal tissues (
b
). Biopsy revealed grade II–III mast cell tumor.
Chapter 1.10
Figure 1.10.1
Hyoid Trauma (Canine) CT
5y FS Jack Russell Terrier with a 3-month history of coughing, gagging, and nasal discharge. Images
a
and
b
are the same image with and without annotation. These are 5 mm collimated transverse images that include the basihyoid bone (
b
: arrowhead), caudal ends of the ceratohyoid bones (
b
: small arrows), portions of the epihyoid bones (
b
: large arrows), and the distal end of the left stylohyoid bone (
b
: black arrow). The caudal end of the angular process of the right mandible is also seen (
b
: black arrowhead). The right epihyoid bone is displaced laterally, indicative of trauma.
Figure 1.10.2
Hyoid Trauma (Feline) CT
9y MC Domestic Shorthair with acute head and neck trauma of unknown cause. The cat also had difficulty swallowing on physical examination. There is asymmetry of the hyoid apparatus with medial displacement of the left epihyoid and stylohyoid bones (arrow). Swallowing function improved following 3 days of supportive care.
Figure 1.10.3
Hematoma (Canine) MR
8y MC Golden Retriever. Previous endoscopy (1 week prior) with laryngeal biopsy resulted in a hematoma. A large, well-circumscribed mass that is hypointense to muscle on T1 sequences and hyperintense to muscle on T2, PD, and FLAIR sequences is present in the right cranioventral cervical region adjacent to the larynx (
a
: arrows). There is a thin, peripheral rim of enhancement on contrast-enhanced images (
d
: arrowhead). The mass partially suppresses on the FLAIR image (
e
).
Figure 1.10.4
Nasopharyngeal Polyp (Feline) CT
4y FS Domestic Shorthair with upper respiratory noise and open-mouth breathing. There is soft-tissue attenuating material filling the nasopharynx and choana on transverse images (
a
,
b
: arrows). The mass is well circumscribed and peripherally contrast enhancing (
c
: arrowhead). The left tympanic bulla is filled with a combination of mineral and soft-tissue attenuating material (
d
: open arrow).
Figure 1.10.5
Retropharyngeal Cellulitis (Canine) CT
4y FS Pit Bull Terrier with progressive dyspnea. Representative contrast-enhanced images are at the cranial cervical level and are ordered from cranial to caudal. A contrast-enhancing perilaryngeal and retropharyngeal mass (
a–d
: arrow) is evident, bounded by the longus capitus muscles dorsally (
a–c
: asterisks). The medial retropharyngeal lymph nodes (
a
,
b
: arrowheads) are moderately enlarged and have a nonuniform contrast-enhancement pattern. Biopsy of retropharyngeal tissue confirmed chronic neutrophilic and plasmacytic cellulitis with extensive fibrosis.
Figure 1.10.6
Pyogranulomatous Inflammation (Canine) CT
2y F German Shepherd with ventral cervical swelling. Marked, diffuse ventral cervical swelling is present, associated with loss of fascial plane definition (
a
) and heterogeneous and ill-defined contrast enhancement (
b
). Biopsy revealed pyogranulomatous cellulitis and myositis, likely due to migrating plant awn foreign body.
Figure 1.10.7
Hyoid Neoplasia (Canine) CT
11y FS Labrador Retriever with a diagnosed thyroid carcinoma. A large ventral mass incorporates the hyoid apparatus, obliterating the basihyoid, thyrohyoid, and ceratohyoid bones (
a
,
c
). Remnants of these hyoid components are present within the mass (
a
,
c
: arrows). The mass moderately and heterogeneously contrast enhances (
b
). The thyroid and cricoid cartilages are uninvolved and appear intact (
c
: arrowhead). Aspiration cytology confirmed ectopic thyroid carcinoma.
Figure 1.10.8
Laryngeal Rhabdomyosarcoma (Canine) CT
11y MC English Setter with a left-sided laryngeal mass. Images
a
and
b
are at the level of the larynx. Images
c
and
d
are at the level of the mandibular and medial retropharyngeal lymph nodes, respectively. There is a centrally hypoattenuating left laryngeal mass (
a
,
b
: arrow) that peripherally contrast enhances and causes rotational displacement of the cranial border thyroid cartilage (
b
: arrowhead). Ipsilateral mandibular (
c
: arrows) and medial retropharyngeal (
d
: arrow) lymph nodes appear normal. Biopsy revealed granular cell rhabdomyosarcoma. The dog was alive, and there was no evidence of mass recurrence 4 years following mass excision and permanent tracheostomy.
Figure 1.10.9
Neuroendocrine Tumor (Canine) MR
14y FS Golden Retriever cross with a right ventral cervical mass. Images
d–f
are at the level of the larynx. An irregularly margined, ovoid mass is seen adjacent to the larynx in the region of the right retropharyngeal lymph node. The mass has a solid but heterogeneous center (
a–f
) and markedly contrast enhances (
c
,
f
). The right carotid artery is displaced laterally (
d
: arrow) compared to the left carotid artery (
d
: open arrow). Both thyroid lobes were identified and appeared normal (not shown). Biopsy revealed the mass to be a neuroendocrine tumor of indeterminate origin.
Figure 1.10.10
Neuroendocrine Tumor (Feline) CT
10y FS Siamese with intermittent dyspnea of 1-month duration. A large, predominantly right-sided contrast-enhancing mass (
a
,
b
: asterisk) arises from the right laryngeal wall, displacing and partially occluding the intralaryngeal ostium and caudal nasopharynx (
a
: arrow). Aspiration cytology revealed this mass to be a malignant neuroendocrine tumor.
Figure 1.10.11
Nasopharyngeal Undifferentiated Round Cell Tumor (Canine) CT
2y MC Labrador Retriever with progressive dyspnea. A well-defined, uniformly contrast-enhancing mass arises from the dorsal nasopharyngeal wall and nearly completely obstructs the nasopharyngeal lumen (
a
,
b
: arrow). Endoscopically acquired biopsy (
c
) revealed the mass to be a primitive undifferentiated round-cell tumor.
Figure 1.10.12
Laryngeal Lymphoma (Feline) MR
11y MC Domestic Shorthair with voice change. There is a mass that is isointense on T1 and hyperintense and heterogeneous on T2 surrounding the pharynx and larynx. On contrast-enhanced T1 images, the mass is intensely enhancing (
c
,
f
: arrows). The retropharyngeal lymph nodes (
f
: asterisks) are moderately enlarged. The lymphoma was a large-cell T-cell type.
Chapter 1.11
Figure 1.11.1
Normal Thyroid Glands (Canine) CT
On unenhanced CT images, normal thyroid lobes are typically hyperattenuating as a result of iodine content (
a
,
b
: arrowheads).
Figure 1.11.2
Normal Thyroid Glands (Canine) MR
Left and right thyroid lobes are seen as small, roughly triangular structures on transverse T1 and T2 images (
a
,
b
: arrows) located adjacent to the tracheal wall and ventromedial to the common carotid arteries. Right (
c
: arrow) and left (
d
: arrow) thyroid lobes are well delineated on dorsal plane T1 3D-SPGR images, seen medial to the common carotid arteries (
c
,
d
: arrowhead), which course obliquely through this imaging plane.
Figure 1.11.3
Hypothyroidism (Canine) CT
12y FS Weimaraner with documented hypothyroidism. Image
b
is the same image as
a
with line overlays showing the long-axis oblique planes depicted in
c
and
d
. The thyroid lobes are smaller than expected and are marginally hyperattenuating than adjacent soft tissues (
a
: arrows). The right (
c
: arrows) and left (
d
: arrows) thyroid lobes are easily delineated on the oblique images. Both lobes are small, and margins are abnormally lobular. Thyroid lobes viewed in long axis are distinguished from the medial retropharyngeal lymph nodes which can appear similar but are more cranial and located lateral to the neurovascular bundle.
Figure 1.11.4
Thyroid Adenoma (Feline) CT
7y Himalayan with recent history of dysphagia and anorexia. An ovoid hypoattenuating mass is present in the left ventral cervical region on ultrasound examination (
a
). On CT images, the mass has attenuation less than adjacent soft tissues but significantly more than fat (
b
: arrow). The mass contrast enhances nonuniformly and margins are well defined (
c
: large arrow). The left common carotid artery is displaced dorsally (
c
: small arrowhead), and the left jugular vein is displaced laterally (
c
: large arrowhead). The right thyroid gland appears normal (
c
: small arrow). Excisional biopsy confirmed a diagnosis of thyroid adenoma.
Figure 1.11.5
Thyroid Carcinoma (Canine) CT
12y FS Labrador Retriever with previously diagnosed pulmonary and cervical masses. A spherical hypoechoic nodule is seen in the body of the right thyroid lobe on ultrasound examination (
a
). The mass is mildly hypoattenuating on an unenhanced CT image (
b
: arrow). The left thyroid lobe appears normal in size and is hyperattenuating (
b
: arrowhead). The mass moderately contrast enhances but less so than surrounding normal thyroid tissue (
c
: arrow) and the contralateral thyroid lobe. On dorsal plane maximum-intensity projections (MIP) of contrast-enhanced imaging data, a thick-slab MIP reveals the course of the two common carotid arteries dorsal to the thyroid lobes (
d
: arrowheads). A thinner-slab MIP excluding the carotid arteries reveals the thyroid lobes (
e
: arrows) and the specific location of the mass within the right lobe (
e
: arrowhead). Excisional biopsy revealed solid and follicular thyroid carcinoma with vascular and capsular invasion.
Figure 1.11.6
Thyroid Carcinoma and Thyroid Adenoma (Canine) CT
12y FS Australian Shepherd with a right-sided ventral cervical mass. Ultrasound examination revealed a large, solid vascular mass in the region of the right thyroid lobe (
a
). A smaller hypoechoic mass was seen within the body of the left thyroid lobe (
b
). Unenhanced and contrast-enhanced transverse CT images (
c–f
) are paired and ordered from cranial to caudal. A large right-sided, uniformly contrast-enhancing mass is present (
c–f
: large arrow). The mass margin is poorly defined ventrally, and there appears to be extracapsular extension of the mass and diffuse enhancement of adjacent tissues (
e
,
f
: arrowhead). A normal-appearing left thyroid lobe is seen on the more cranial CT image (
c
,
e
: small arrow). On the more caudal image, the left thyroid lobe is larger and has lower attenuation characteristics than expected, suggesting the presence of a second smaller left thyroid mass (
d
,
f
: small arrow). CT imaging findings are further documented on long-axis oblique axis reformatted CT images, and now two small nodules are seen in the left thyroid lobe (
h
: small arrows). Imaging findings were corroborated at the time of surgical excision (
i
,
j
: arrows). Excisional biopsy revealed right-sided thyroid carcinoma with extracapsular invasion and left-sided thyroid adenoma.
Figure 1.11.7
Thyroid Carcinoma (Canine) CT
10y MC Rottweiler with a 4-month history of a ventral cervical mass. A large well-margined ovoid mass is seen in the right ventral cervical region. The mass is moderately and uniformly contrast enhancing (
a
: asterisk). The left thyroid lobe appears normal in size, location, and density (
a
: arrowhead), but a normal thyroid lobe was not identified on this study. 3D renderings reveal the specific location of the mass in relation to the jugular veins (
b–d
: large arrows) and common carotid arteries (
c
,
d
: arrowheads). Vascular supply to the mass from the cranial and caudal thyroid vessels can also be seen (
b–d
: small arrows). A well-encapsulated mass was excised (
e
). Excisional biopsy confirmed a diagnosis of thyroid carcinoma.
Figure 1.11.8
Invasive Thyroid Carcinoma (Canine) CT
10y MC Labrador cross with a 3-month history of dysphagia and ventral cervical mass. Representative CT images are paired unenhanced (
a–c
) and contrast-enhanced (
d–f
) images ordered from cranial to caudal. An extensive soft-tissue mass with heterogeneous attenuation is seen in the right cervical region, extending from the hyoid apparatus rostrally to the mid-cervical region caudally. The mass displaces the larynx to the left, crosses midline, and extends into the dorsal and left lateral laryngeal and retropharyngeal regions. The mass is highly and heterogeneously contrast enhancing. The mass displaces the larynx to the left, invades the laryngeal soft tissues (
e
: small arrow), and incorporates the carotid artery and internal jugular vein on the right (
e
: black arrow). There are filling defects and distension of these vessels caudally (
f
: arrowheads) and of the right facial vein (
d
: arrowhead), indicating tumor invasion and the presence of tumor thrombus. The left retropharyngeal lymph nodes are enlarged and have a heterogeneous pattern of enhancement (
e
: arrowhead), suggesting contralateral regional lymph node metastasis. Postmortem examination confirmed a diagnosis of thyroid carcinoma involving both thyroid lobes with extensive infiltration into the adjacent soft tissues and metastasis to regional lymph nodes and lung. The mass extended into and expanded the oropharyngeal wall with marked compression of the pharynx and laryngeal opening.
Figure 1.11.9
Invasive Thyroid Carcinoma (Canine) CT
6y MC Old English Sheepdog with anorexia and right-sided laryngeal paralysis. On ultrasound images, the mass is hypoechoic and highly vascular (
a
,
b
). The mandibular lymph nodes are enlarged with nonenhancing central nodules, suggestive of metastatic disease (
c
: arrowhead). The diffuse, contrast-enhancing neoplastic tissue invades the larynx and cervical musculature (
d
,
e
: arrows). There is also a mass effect in the spinal canal associated with cord displacement and compression (
e
: asterisk). This either represents vascular invasion of tumor into the internal venous plexus or venous obstruction. There is esophageal invasion (
f
: small arrows) and tortuous vasculature surrounding the mass (
f
: large arrow). There is invasion of the subvertebral musculature caudally (
g
: arrowheads). Unidentified tumor vessels are enlarged and filled with tumor thrombus (
h
: asterisks).
Figure 1.11.10
Ectopic Thyroid Carcinoma (Canine) MR
8y MC Labrador Retriever with recent weight loss and elevated T4 level. A partially mineralized mass is seen ventral to the hyoid apparatus and appears to involve the basihyoid bone (
a
: arrow). The mass appears solid and highly vascular on ultrasound images (
b
,
c
), and partial mineralization is again noted (
b
: shadowing). Marked uptake of technetium pertechnetate on a thyroid scintigraphic examination (not shown) confirmed thyroid origin of the mass. The mass is of mixed intensity on unenhanced T1 and T2 images (
d
,
e
,
g
,
h
) and moderately contrast enhances (
f
,
i
). Mass margins are poorly defined on the transverse images, suggesting invasion of the adjacent geniohyoideus and mylohyoideus muscles (
g–i
: small arrows). The mass also incorporated the basihyoid bone, which could not be seen on any images. Surgical excision was incomplete because of extensive laryngeal involvement.
Figure 1.11.11
Ectopic Thyroid Carcinoma (Canine) CT
10y F Shetland Sheepdog with swelling of the face and neck. There is a large, heterogeneous mass in the cranial mediastinum (
a
: arrowheads). The mass is causing dorsal displacement of the trachea (
a
,
b
) and caudal displacement of the heart (
c
). On contrast-enhanced images (
b
,
c
), there is heterogeneous enhancement and filling defects representing tumor thrombus within the cranial vena cava (
b
: arrows). Histologic diagnosis and anatomic distribution were confirmed on postmortem examination.
Figure 1.11.12
Malignant Carotid Body Tumor (Canine) CT
9y FS Boston terrier with a cervical mass. Carotid body tumors (Chemodectoma) are similar in location to thyroid masses. However, the normal, high-attenuating thyroid lobes are easily identified adjacent to the tracheal wall on the unenhanced image in this patient (
a
: arrows). The carotid body tumor is highly vascular and intensely contrast enhancing. In comparison to thyroid tumors where the carotid artery is usually displaced laterally, the carotid artery is contained within the mass (
b
: open arrow). Regional lymph node metastasis (not shown) was also confirmed from surgical excisional biopsy.
Figure 1.11.13
Parathyroid Carcinoma (Canine) MR
12y M Golden Retriever with hypercalcemia. There is a hypoechoic nodule seen in the cranial pole of the left thyroid lobe on ultrasound (
a
: calipers). On MR imaging, the mass is isointense on T1 images and hyperintense on T2 images (
c
: white arrow) within the thyroid gland (
c
: black arrows). The histologic diagnosis was documented on postmortem examination.
Chapter 1.2
Figure 1.2.1
Normal Ear (Canine) CT
The normal canine ear on CT examination with thin collimation and bone algorithm. The vestibular aqueduct (AV) contains an extension of the membranous labyrinth and connects with the meninges of the brain. The cochlea is visible as a small, circular structure (C). The incus (I) and malleolus (M) are visible in the dorsal portion of the ear. The air-filled space of the ear is divided into the tympanic cavity (TC) and tympanic bulla (TB) by the tympanic septum (not shown).
Figure 1.2.2
Normal Ear (Canine) MR
MR images of the normal canine ear. A transverse T1 image is shown on the left, T2 on the right. The cochlea is visible as a hyperintense structure on the T2 image (
b
: arrowhead).
Figure 1.2.3
Otitis Externa (Canine) CT
1y MC Maltese with a history of chronic otitis externa. The external ear canals are occluded because of stenosis and exudates (
a
). Contrast-enhanced images show marked enhancement and redundancy of the external ear canal walls (
b
,
c
). Gas and fluid within the canal lumen can be distinguished from adjacent enhancing epithelium (
b
). Biopsy revealed severe diffuse chronic lymphoplasmacytic otitis externa with epithelial hyperplasia and ceruminous and sebaceous gland hyperplasia.
Figure 1.2.4
Inflammatory Polyp—External Ear (Feline) CT
1y MC Domestic Shorthair with history of right-sided ear infections. Fluid/soft-tissue opacity within the right external ear canal and tympanic bulla is indicative of otitis externa and otitis media (
a
). On a contrast-enhanced image, a well-delineated contrast-enhancing mass is seen within the horizontal part of the right external ear canal and the bulla (
b
: arrow). The mass is distinguished from nonenhancing fluid in the bulla. An excisional biopsy revealed inflammatory polyp and suppurative otitis externa.
Figure 1.2.5
Obstructive Bulla Effusion—Nasopharyngeal Polyp (Feline) CT
3mo F Domestic Shorthair with a history of stertor and increased respiratory effort. Bilateral tympanic bulla effusion is seen, associated with mild bulla wall thickening (
a
). A large polyp completely occludes the nasopharyngeal lumen (
b
,
c
: arrow). The nasopharyngeal mass likely occludes the auditory canals, resulting in obstructive bulla effusion. The polyp was removed endoscopically using traction.
Figure 1.2.6
Otitis Externa and Media with Abscessation and Cellulitis (Canine) CT
3y MC Cocker Spaniel with a history of bilateral chronic otitis externa. A right-sided external ear canal ablation procedure was performed 2 years prior to the CT examination. A poorly marginated, fluid-filled mass is present adjacent to the right middle ear (
a
: asterisk). The mass is peripherally contrast enhancing, and enhancement extends along subcutaneous and interfascial planes. The right tympanic bulla is fluid filled, indicative of otitis media. The ipsilateral mandibular lymph nodes are enlarged (
a
: arrowhead). The 3D colorized rendering illustrates the prominent vascular density of the periphery of the lesion (
b
: arrows). Excisional biopsy revealed severe chronic granulomatous inflammation with intralesional ceruminous debris.
Figure 1.2.7
Otitis Media (Canine) MR
10y M Golden Retriever with uncomplicated otitis media. The tympanic bulla contains material of mixed intensity on both the unenhanced T1 image and the T2 image (
a
,
b
). The majority of the contents contrast enhance in the periphery of the bulla, indicating a pronounced thickening of the bulla lining (
c
). The nonenhancing regions represent entrapped fluid. The wall of the bulla is nonuniform in thickness and is irregularly margined because of reactive bulla osteitis (
c
). External ear canal stenosis, canal wall thickening, and marked contrast enhancement are indicative of concurrent otitis externa.
Figure 1.2.8
Otitis Media with Thickened Tympanic Bulla (Canine) CT
5y FS Labrador Retriever with a history of chronic bilateral otitis externa. Both external ear canals and tympanic bullae are filled with fluid-attenuating material. The left tympanic bulla cavity has expanded. There is a marked irregular proliferative bony response involving both bulla walls. The proliferative response is consistent with reactive osteitis associated with chronic otitis media.
Figure 1.2.9
Otitis Media and Interna—Cranial Nerve VIII Involvement (Canine) CT
6y MC Cocker Spaniel with chronic ear infections. Bilateral ear canal ablations were performed 2 years previously, and the dog has recently developed right-sided peripheral vestibular signs. On sequential unenhanced images, the right tympanic bulla is filled with fluid-attenuating material, and there is partial osteolysis of the bulla wall laterally. The right internal acoustic meatus (
b
: arrowhead) and a portion of the cochlea (
b
: arrow) are seen. On contrast-enhanced images, there is enhancement of tissues surrounding the tympanic bulla consistent with a clinically confirmed abscess. There is also focal intracranial contrast enhancement in the location of the cochlear branch of the vestibulocochlear nerve (
c
,
d
: arrow), suggesting extension of disease through the internal acoustic meatus.
Figure 1.2.10
Otitis Media and Interna with Intracranial Extension (Canine) MR
13y West Highland White Terrier with a history of chronic otitis externa/media. A left-sided external ear canal ablation and bulla osteotomy were performed 18 months previously. The dog currently has peripheral vestibular signs. Images
a–d
are all at the same level. Image
e
is slightly more caudal. The residual bulla cavity is fluid and tissue filled. There is increased signal intensity of the left petrous temporal bone on all image sequences. There is also focal T2 hyperintensity of the left vestibulocochlear nerve (
b
: arrowhead), which is seen as increased signal intensity on the FLAIR sequence (
c
: arrowhead), suggesting cranial nerve VIII neuritis. Focal meningeal and petrosal contrast enhancement are present (
d
: arrow), indicative of meningitis. Enlargement of the left vestibulocochlear nerve is also seen on contrast-enhanced images (
e
: arrowhead).
Figure 1.2.11
Otitis Media and Interna—Meningeal Enhancement (Feline) MR
11y FS Domestic Shorthair with 1-week history of left-sided peripheral vestibular signs. Images
a–c
were acquired at the same anatomic level. Image
d
is slightly more caudal. The tympanic bullae contain material consistent with exudative fluid based on T1 and T2 signal characteristics. Marked thickening of the bulla epithelial lining is evident on contrast-enhanced images (
c
,
d
). In addition, there is enhancement of the soft-tissue structures encased within the left osseous labyrinth (
c
: arrow). Focal meningeal enhancement is also evident adjacent to the internal surface of the petrous temporal bone (
d
: arrowhead). This constellation of imaging features is consistent with otitis media, otitis interna, and regional meningitis. Contrast enhancement within fascial planes adjacent to the left tympanic bulla is indicative of cellulitis (
d
: arrow). Biopsy acquired at the time of bulla osteotomy revealed lymphohistiocytic and neutrophilic otitis media.
Figure 1.2.12
Cholesteatoma (Canine) CT
15y FS Miniature Poodle with a 6-month history of right-sided otitis externa. Marked expansion and osseous remodeling of the right tympanic bulla is seen. Soft-tissue attenuating material fills the bulla and the horizontal ear canal. Bulla contents and soft tissues adjacent to the bulla wall are mildly contrast enhancing. Histologic features of biopsy material were consistent with cholesteatoma.
Figure 1.2.13
Cholesteatoma with Otitis Interna (Canine) MR
7y FS French Bulldog with head tilt. There is a well-demarcated expansile mass emanating from the left tympanic bulla, which has eroded the petrous temporal bone and adjacent occipital bone, extends into the cranial vault, and has resulted in brainstem deformation. The mass is heterogeneous but T1 hypointense and moderately T2 hyperintense. There is irregular peripheral contrast enhancement (
c
: small arrows) and adjacent meningeal enhancement (
c–e
: large arrow). Similar signal changes are noted in the right tympanic bulla but are confined within the bulla cavity. Pronounced left-sided temporal, masseter, and pterygoid muscle atrophy is also evident. Biopsy revealed neutrophilic inflammatory response with abundant keratin-like debris consistent with cholesteatoma.
Figure 1.2.14
Ceruminous Adenoma—External Ear (Feline) CT
8y MC Domestic Shorthair with unilateral otitis externa. A well-delineated contrast-enhancing mass is seen within the horizontal part of the right external ear canal on contrast-enhanced images (
a
,
b
: arrow). Fluid is entrapped between the tympanic membrane and the mass in the proximal part of the canal (
a
: arrowhead). Thickening of the ipsilateral tympanic bulla and a small volume of exudate adherent to the bulla wall are suggestive of previous otitis media. Excisional biopsy revealed ceruminous adenoma of the external ear canal and chronic otitis externa.
Figure 1.2.15
Ceruminous Adenocarcinoma (Canine) CT
11y FS Lhasa Apso with a previously diagnosed right-sided ceruminous gland adenocarcinoma that was partially excised as part of an external ear canal ablation 1 year prior to the CT scan. Complete osteolysis of the tympanic bulla and partial osteolysis of the petrous temporal bone are evident on the unenhanced CT image (
a
). A large soft-tissue mass is present adjacent to the skull base, causing laryngeal displacement to the left of midline. Mass margins are ill defined, and normal fascial planes are obscured. The mass enhances on the contrast-enhanced image (
b
). Margins are moderately well defined, but there is intracranial extension of the mass through the petrous temporal bone defect.
Figure 1.2.16
Squamous Cell Carcinoma (Canine) CT
12y FS Golden Retriever with a mass associated with the right ear. A large, irregularly margined mass arises from the right middle ear (
a
). The external ear canal is not evident, and osteolysis of portions of the tympanic, petrosal, and squamous parts of the temporal bone is seen. The mass moderately and heterogeneously contrast enhances, and the bulk of the mass appears to be contained by the residual bulla and grossly distended external ear canal (
b
: arrowheads). There is also intracranial extension of the mass through a fenestration in the temporal bone (
b
: arrow). Ill-defined contrast enhancement is also present in peritumoral tissues. Biopsy of the mass revealed aural squamous cell carcinoma.
Figure 1.2.17
Squamous Cell Carcinoma (Canine) MR
7y MC Labrador Retriever with a 1-month history of head tilt. There is a large, irregularly margined, and highly invasive mass of mixed-signal intensity arising from the region of the right middle ear (
a
,
b
). An amorphous signal void seen centrally within the mass on multiple sequences suggests partial mineralization. The right tympanic bulla is absent, and incomplete destruction of the petrosal and squamous parts of the right temporal bone is evident. The mass extends intracranially (
a
,
b
,
c
,
f
: arrow) and incorporates the right temporomandibular joint (
d
,
e
). Biopsy revealed squamous cell carcinoma.
Figure 1.2.18
Cartilage Mineralization (Canine) CT
6y M German Shepherd Dog with longstanding history of bilateral otitis externa. Pronounced mineralization of the horizontal and vertical external ear canal walls is evident (
a
,
b
). External ear canals are occluded because of stenosis and exudates (
a
,
b
). Fluid-attenuating material is also present within the left tympanic bulla, indicative of concurrent otitis media (
a
). Biopsy of the canal wall revealed chronic neutrophilic otitis externa with osseous metaplasia.
Figure 1.2.19
Otitis Media with Otolith (Canine) CT
9y MC Australian Shepherd with chronic nasal discharge. The left tympanic bulla is fluid filled and contains multiple discrete mineral opacities. Biopsy acquired during bulla osteotomy yielded a histologic diagnosis of chronic otitis media with inspissated and mineralized debris.
Chapter 1.3
Figure 1.3.1
Normal Tempormandibular Joint (Canine) CT
7y MC Australian Shepherd. Osseous structures are well visualized on CT images, although the intrinsic soft tissue structures of the joint are not clearly delineated.
Figure 1.3.2
Normal Temporomandibular Joint (Canine) MR
2y M Pit Bull Terrier. The condyloid process and region of the mandibular fossa appear T1 and T2 hyperintense centrally because of medullary fat, with a well to poorly defined signal void peripherally defining the subchondral bone margins. The apparent irregularity of the subchondral bone of the condyle on transverse images is due to partial volume averaging.
Figure 1.3.3
Subchondral Cyst of the Condylar Process (Canine) CT
3y M Rottweiler. A CT scan of the head was performed as part of a diagnostic evaluation for chronic otitis. A well-delineated circular subchondral bone cyst is seen in the left mandibular condylar process (
a
). Contents are fluid-dense and surrounded by a thin rim of compact bone. The left condyle (
b
) is unremarkable and included in this figure in the same orientation for comparison. The cyst was clinically silent and identified as an incidental finding on this study.
Figure 1.3.4
Subchondral Cyst of the Condylar Process (Canine) MR
Adult MC Weimaraner. The MR study was part of a diagnostic evaluation of central neurologic signs. A well-delineated circular subchondral bone cyst is seen in the left mandibular condylar process. The center of the cyst has high water content, as suggested by the T2 hyperintensity and unenhanced T1 hypointensity. The low signal seen on the FLAIR image further suggests low cellular or macromolecular concentration, although the center does mildly contrast enhance.
Figure 1.3.5
Mandibular Condylar Dysplasia (Canine) CT
10mo MC Bassett Hound with a history of pain when opening the mouth and periodic episodes of inability to close the mouth. The sagittal reformatted image is oriented rostral to the left and caudal to the right. The left manibular condyle is misshapen (
a
,
b
: asterisk), and there is evidence of subluxation of the temporomandibular joint (
a–c
: arrow). The sagittal image reveals abnormal flattening of the articulating surfaces and striking hypoplasia of the retroarticular process resulting in ventral subluxation (
b
: arrowhead). Temporomandibular joint findings were bilaterally symmetrical in this dog.
Figure 1.3.6
Mandibular Condylar Dysplasia with Unilateral Luxation (Canine) CT
3y MC Lhasa Apso presented to the emergency service with temporomandibular luxation. The representative transverse images (
a
,
b
) are ordered from caudal to rostral. The left condyloid process is luxated rostrodorsally (
b
,
d
,
e
: arrow), and the right condyloid process is subluxated (
a
,
c
). The condyloid processes are misshapen, and the mandibular fossae are flattened with hypoplastic retroarticular processes (
c
: arrowheads).
Figure 1.3.7
Craniomandibular Osteopathy (Canine) CT
1y MC Golden Retriever with a history of mandibular swelling and pain. The representative transverse images (
a–c
) are ordered from rostral to caudal. There is marked, irregular, periosteal productive response that is symmetrically affecting the caudal mandible and temporomandibular joints. This productive response has extended to the temporomandibular joints (
a
: black arrows) and involves the temporal bones (
b–d
: arrows).
Figure 1.3.8
Unilateral Temporomandibular Joint Luxation (Feline) CT
Mature MC Domestic Shorthair hit by a car within the past 24 hours. The representative transverse images are ordered from rostral to caudal. Images reveal a rostral and dorsal luxation of the right mandibular condylar process (
a
,
b
: arrow).
Figure 1.3.9
Temporomandibular Fracture–Luxation (Canine) CT
1y MC Lhasa Apso with a history of having fallen off a ledge. The representative transverse images are ordered from rostral to caudal. The two images reformatted in the sagittal plane are oriented in the same direction for easier comparison. In both images, rostral is to the left and caudal is to the right. There is caudal luxation of the left condyloid process. Although the head position is symmetrical, the left process is not seen on the rostral image (
a
) but comes into view on a more caudal image (
b
: arrow). The sagittal reformatted image of the left temporomandibular joint (
c
) clearly shows the caudal luxation as well as a caudally displaced fracture of the retroarticular process (
c
: arrowhead). The fracture fragment is also evident on the transverse images (
b
: arrowhead). The appearance of the right temporomandibular joint (
d
) is normal by comparison. Fluid is also seen within the left external ear canal (
b
).
Figure 1.3.10
Inflammatory Mandibular Mass with Temporomandibular Subluxation (Feline) CT
12y FS Domestic Shorthair with iatrogenic open wound in the oropharyngeal region following a traumatic pill administration. Clinical signs included malocclusion, oral pain, and inability to close the mouth. The cat had a previous enucleation that is unrelated to the current presenting complaint. The transverse images are comparable unenhanced and contrast-enhanced images. The two images reformatted in the sagittal plane are oriented in the same direction for easier comparison. In both images, rostral is to the left and caudal is to the right. A heterogenously contrast-enhancing mass is evident surrounding the body of the mandible on the left (
b
: arrowhead). The left temporomandibular joint is subluxated as a result of extraarticular encroachment by the mass (
c
: arrow). The right temporomandibular joint is normal by comparison (
d
). Biopsy of the oropharyngeal region confirmed the presence of suppurative abscess and cellulitis.
Figure 1.3.11
Condylar Fossa Fracture (Canine) CT
1y German Shepherd Dog hit by a car 24 hours previously. The representative transverse images are ordered from rostral to caudal. A transverse fracture is seen in the rostral part of the right zygomatic bone near its articulation with the maxilla (
a
: arrow). A second, mildly displaced comminuted articular fracture is present near the origin of the zygomatic process of the right temporal bone (
b–d
: arrow). Another fracture line is evident coursing parallel to the subchondral bone margin of the fossa (
b
: arrowheads).
Figure 1.3.12
Temporomandibular Septic Arthritis (Canine) MR
8y FS Rhodesian Ridgeback with regional cellulitis associated with otitis media/interna. T2 hyperintensity is seen adjacent to the medial margin of the right temporomandibular joint, the right lateral pterygoid muscle, and the dorsal aspect of the pharynx (
a
: arrows). The same region contrast enhances (
b
: large arrows), and additional meningeal enhancement is evident (
b
: small arrows). There is periarticular contrast enhancement involving the right temporomandibular joint, with associated intraarticular enhancement, and a diminished subchondral signal void (
c
: arrow). The left temporomandibular joint is normal by comparison (
d
).
Figure 1.3.13
Temporomandibular Fibrosarcoma (Canine) CT
6y M Golden Retriever with recent onset of oral pain. A large, aggressive bone-destructive mass is centered on the caudal aspect of the left side of the mandible. Osteolysis of the left mandibular ramus (
a
: arrows) and condyloid process (
b
: arrow) is evident. Bone destruction extends to and includes the subchondral bone of the process, implying an intraarticular component to the mass. On comparable contrast-enhanced images, the mass has a complex, lobular appearance (
c
,
d
). Aspiration biopsy revealed the mass to be a fibrosarcoma.
Figure 1.3.14
Temporal Bone Chondrosarcoma (Canine) MR
8y FS German Shepherd Dog with neurologic signs relating to left cerebral and thalamic disease. A large, locally invasive complex mass arises from the temporal bone, with components extending intracranially and into the adjacent temporal musculature. Left temporal bone medullary signal intensity is reduced on unenhanced T1 images (
a
: arrow) as a result of marrow displacement by the mass, and cortical margins are attenuated. Multiple high intensity foci suggest the mass is multicameral and cystic (
b
). The mass is nonuniformly contrast enhancing (
c
,
d
). Biopsy revealed a highly anaplastic chondrosarcoma.
Figure 1.3.15
Temporomandibular Sarcoma (Canine) MR
8y MC Rottweiler with progressive right temporal and masseter muscle atrophy and pain upon opening the mouth. A poorly margined lobular mass arises in the region of the right mandibular process, resulting in mandibular cortical bone destruction and diminished marrow signal intensity on the unenhanced T1 image (
b
: arrows). The mass is moderately and uniformly contrast enhancing (
c–e
). Replacement of the normal right condyloid process architecture by the mass with extension into the right temporomandibular joint space is best seen on the right sagittal image (
c
: arrow). The left temporomandibular joint is normal by comparison (
f
). Right temporal and masseter muscle atrophy is seen associated with increased T2 and T1 signal intensity (
a
,
d
: asterisk), consistent with dysfunction of the mandibular branch of the right trigeminal nerve. Aspiration biopsy of abnormal spindle cells was consistent with sarcoma.
Figure 1.3.16
Temporomandibular Osteoarthrosis (Canine) CT
6y MC Miniature Schnauzer with a history of difficulty opening its mouth. Tests to assess for the presence of immune-mediated joint disease were negative. In the sagittal image, rostral is oriented to the left and caudal is to the right. Marked narrowing of the temporomandibular joint space is evident on both the transverse and sagittal images (
a
,
b
), implying a loss of articular cartilage and meniscal degeneration. Imaging findings are consistent with temporomandibular osteoarthrosis.
Figure 1.3.17
Temporomandibular Partial Ankylosis (Canine) CT
5y FS Labrador Retriever with a history of chronic otitis externa, a 1-year history of pain on opening the mouth, and more recent in-ability to open mouth. Image
b
represents a magnified view of the left temporomandibular joint from image
a
. In the sagittal image (
c
), rostral is oriented to the left and caudal is to the right. Subchondral bone remodeling of the left condylar process (
b
,
c
: asterisk) and marked periarticular bone proliferation surround the left temporomandibular joint. Reactive bone surrounds the medial and ventral aspect of the condylar process (
b
: arrowheads) and the angular process (
b
,
c
: large arrows). The left zygomatic process is thickened and sclerotic (
b
: small arrow). Milder changes to the right temporomandibular joint are also evident (
d
).
Chapter 1.4
Figure 1.4.1
Occipitoatlantoaxial Dysplasia (Canine) CT
8mo MC Yorkshire Terrier with atlantoaxial instability. An imaging diagnosis of occipital dysplasia was made as a component of a more complex anomaly of the atlantoaxial–occipital region. The transverse image is of the caudal aspect of the occipital bone at the level of the foramen magnum. The foramen magnum is larger than normal and elongated in the dorsal–ventral axis (
a
,
b
: two-headed arrow). The rostral margin of the dorsal arch of the atlas extends into the dorsal part of the foramen resulting in atlantooccipital overlapping (
a
,
b
: arrowhead). The occipital condyles (
c
: arrows) are hypoplastic but appear to articulate well with the articular fovea of the atlas (
c
: arrowheads). Marked rotational subluxation of the atlantoaxial joint is evident, and the odontoid process of the axis is hypoplastic (
b
).
Figure 1.4.2
Benign Calvarial Hyperostosis (Canine) CT
1y M Bernese Mountain Dog with prominent midline cranial mass. An irregular but well-defined osseous mass arises from the dorsal calvarium. The proliferative mass is dense and highly organized and has no appreciable overlying soft-tissue component. Bone biopsy revealed essentially normal bone tissue with considerable woven bone embedded in dense fibrous tissue overlying lamellar bone. This entity has previously been described in young Bull Mastiffs.
Figure 1.4.3
Acute Skull Fracture (Canine) CT
5y MC Pomeranian hit by a car earlier in the day. There is a depression fracture of the left side of the calvarium involving the interparietal suture (small arrow), the right parietal bone (large arrow), and the right parietotemporal suture (arrowhead). The dog also sustained multiple fractures involving the mandible, resulting in the asymmetry seen here. Additional CT or MR imaging is indicated to evaluate the extent of intracranial trauma.
Figure 1.4.4
Skull Fractures (Feline) CT
5y MC Domestic Shorthair that sustained trauma of unknown cause within the past 48 hours. This cat sustained a number of skull fractures commonly associated with high-impact trauma. Representative images are ordered from rostral to caudal. Injuries include a fracture–luxation involving the nasal and maxillary bones (
a
: arrow), mandibular symphyseal separation (
b
: arrow), fractures of the perpendicular processes of the palatine bones (
c
: arrows), separation of the palatine symphysis (
c
: arrowhead), fractures of the pterygoid bones (
d
: arrows), caudal luxation of the right condyloid process (
e
: arrowhead), and a fracture through the zygomatic process of the left temporal bone (
e
: arrow).
Figure 1.4.5
Masticatory Myositis (Canine) CT
1.5y MC Rottweiler with rapidly progressive inability to open mouth. Representative CT images were acquired immediately following contrast medium administration. There is moderate, diffuse contrast enhancement of the left masseter and temporal muscles (
a
,
b
: arrows). Pterygoid muscles appear relatively unaffected (
a
,
b
: arrowhead). Muscle biopsy revealed diffuse, chronic, lymphoplasmacytic myositis with muscle atrophy and fibrosis.
Figure 1.4.6
Masticatory Myositis (Canine) MR
9mo Miniature Pinscher with recent onset of left temporal muscle atrophy. The unenhanced T1 and T2 images are at the same anatomic level. The contrast-enhanced T1 image is more caudal. Marked atrophy of the left temporal muscle and moderate atrophy of the left masseter muscle are evident on all sequences. There is a pronounced increase in signal intensity of affected temporal (
a
: large arrows), masseter (
a
: small arrow), and pterygoid (
a
: arrowheads) muscles on the T2 image that corresponds to regions of mild hyperintensity present on the T1 image (
b
). The same regions markedly contrast enhance (
c
). Serum creatinine kinase was significantly elevated and an antibody test confirmed the diagnosis of masticatory myositis.
Figure 1.4.7
Masticatory Myositis (Canine) MR
8y FS Golden Retriever with a 2-week history of weight loss, stridor, cranial nerve deficits, and temporal muscle atrophy. Bilaterally symmetrical temporal muscle atrophy is evident on all sequences. There is marked, diffuse, and symmetrical hyperintensity of temporal (
c
: large arrows), masseter (
c
: small arrows), and pterygoid (
c
: arrowheads) muscles on the T2 and STIR images corresponding to regional enhancement on the contrast-enhanced T1 image (
b
). A similar diffuse T2 hyperintensity and contrast enhancement pattern of the laryngeal tissues is evident (
b
: arrow). Necropsy revealed severe, bilateral, chronic, and diffuse lymphoplasmacytic myositis with myonecrosis and myodegeneration. This dog also had laryngeal cellulitis.
Figure 1.4.8
Temporal Muscle Abscess (Canine) CT
9y FS Chow with pain when opening mouth. A focal draining lesion was seen in the caudal oral cavity. The contrast-enhanced image shows a poorly delineated cavitary lesion within the left temporal muscle, consistent with an intramuscular abscess (
b
: arrow). Peripheral contrast enhancement extends to the medial surface of the coronoid process of the left mandible and to the external surface of the left parietal bone, but overt bone reactivity is not appreciated. Fascial and muscle contrast enhancement is also evident ventrally (
b
: arrowheads), indicative of more diffusely distributed cellulitis. Biopsy revealed chronic suppurative cellulitis.
Figure 1.4.9
Osteomyelitis (Canine) CT
1y Pit Bull Terrier with an 8-month history of progressive right-sided head and facial swelling. Representative images are unenhanced (
a
,
b
) and contrast enhanced (
c
,
d
) at comparable anatomic levels. Images are ordered from rostral to caudal. Marked asymmetry of the head is evident, and the underlying mass has both a soft tissue and an osseous component (
a
,
b
). A peripherally contrast-enhancing cavitary lesion is seen within the right temporal muscle, consistent with an abscess and surrounding cellulitis (
c
). Dense osteoproliferation is seen involving the right and left parietal bones (
a
,
b
). An involucrum is present toward the caudal aspect of the proliferative bone mass (
b
: arrow) and contains a focal mineral-dense body consistent with a sequestrum (
d
: arrow). Biopsy of bone and associated soft tissues revealed severe, chronic, suppurative, and necrotizing osteomyelitis with reactive new bone formation. The hyperostotic component of this lesion could represent underlying benign calvarial hyperostosis that became infected.
Figure 1.4.10
Osteoma (Canine) CT & MR
2y MC Golden Retriever with cranial mass. There is a smooth, dense production of bone centered on the parietal bone and expanding both intracranially and extracranially. The mass is hyperattenuating and uniform on CT images (
a
). On MR images, the mass effect is evident with compression of the brain and lateral ventricle next to the mass (
b
,
c
), as well as displacement of the falx cerebri to the right (
d
