Fig. 4.1
Cellulitis in the left orbital cavity. (a) Cross-sectional CT image in soft tissue window showed widely swelling and thickening of left eyelid, soft tissue on the left temporal and back of nose regions. (b) Cross-sectional T1WI without enhancement administration showed the blurred margined lesion with inhomogeneous slightly lower SI. (c) Cross-sectional T2WI showed mixed inhomogeneous hyper-intensity. (d) After contrast enhanced, the cross-sectional MR image showed inhomogeneous enhanced lesion, which was extended to superior orbital fissure posteriorly. The boundary between the lesion and lacrimal gland was not clear. The temporal pole meningeal was thickened and enhanced (white arrow). There was patchy of enhancement in the greater wing of sphenoid bone (black arrow)
Fig. 4.2
Cellulitis in the left orbital cavity. (a) Coronal CT image in soft tissue window showed widely swelling and thickening of the left temporal and facial soft tissue (secondary inflammation due to inappropriate management after trauma) (white arrow). (b) Coronal CT image in soft tissue window showed swelling of the left zygomaticofacial soft tissue (asterisk) and widely distributed cable strip shadow in the intra- and extraocular muscle cone space with blurred margin (long arrow). There was soft tissue in the left ethmoid sinus and maxillary sinus (short arrow)
Fig. 4.3
Subperiosteal abscess secondary to nasal source cellulitis in the right orbital cavity. (a) Cross-sectional CT image in soft tissue window showed strip shaped soft tissue in the nasal side of right orbital cavity, which is not separate from the medial rectus. The adjacent ethmoid sinus was filled with soft tissue density. (b) Cross-sectional T1WI without enhancement showed inhomogeneous iso-intensity lesion with strip shaped hypo-intensity in the center. The lesion in the orbital cavity and the ethmoid sinus were not separated clearly. The fat in the extraocular muscle cone space disappeared. (c) Cross-sectional T2WI showed mixed hyper-intensity in the right orbital cavity and ethmoid sinus. The medial rectus was thickened with increased SI, which was not separated from the lesion. (d) Cross-sectional contrast enhanced T1WI with fat saturation showed significant inhomogeneous enhanced lesion in the orbital cavity, with strip shaped unenhanced part in the center. The lesion in the right ethmoid was significantly enhanced
4.1.4 Evaluation
The diagnostic value of traditional X-ray is limited. Ultrasound is a noninvasive examination. It is fast and easy to be used, which can indicate the pathological stage according to the altered echo. But it cannot observe abnormalities deep in the orbital cavity, nor can reveal alternations adjacent to the lesion. CT and MRI scans can comprehensive and objective display the range of lesion and adjacent structures and combined osteomyelitis, sinusitis, foreign body, etc. They are important methods used for the clinical diagnosis and therapeutic evaluation of orbital cellulitis. The diagnosis and differential diagnosis of cellulitis are based on combination of clinical history, clinical manifestation, and radiologic manifestations.
4.2 Idiopathic Orbital Inflammation
4.2.1 Pathological Features
- 1.
Lymphocytic infiltration type: Scattered distributed or infiltrated with large amount of lymphocytes, plasma cells, and (or) eosinophilic cells.
- 2.
Constrictive type: Hyperplasia of large amount of fibrous connective tissue placed in rope or clumps shape. Parts of the lesion are hyaline changed or degenerated. Only small amount of lymphocytes and (or) plasma cells infiltrated.
- 3.
Mixed type: Represent as mixed fibrous connective tissue with infiltrated and hyperplastic chronic inflammation cells. Collagen fiber wraps around the lesion. Parts of the collagen fiber are hyaline changed or degenerated (Mouriaux et al. 2014).
4.2.2 Order of the Imaging Examination
- 1.
Ultrasound. Ultrasound can reveal the structure, characterization of the lesion and its relationship with adjacent soft tissue.
- 2.
CT scan. CT can show the shape, size, location of the lesion and spatial positioning it. It can also show the secondary changes around the lesion. CT scan is recommended.
- 3.
MRI scans. MR images can show the lesion clearly. It can indicate the structure of the lesion according to its different SI.
4.2.3 Radiologic Features
- 1.
Ultrasound: The results are complicated. The echoic features are varied according to the growth pattern and involved structures. If the lesion grows like a mass, it can be a mass shaped lesion with clear margin, low echo-level inside, and blurred posterior margin, which can arise from both the intra- and the extraocular muscle cone space. For the diffused inflammation, the lesions are widespread in the orbital cavity and involve multiple structures. The lesions show inhomogeneous echoes on ultrasound imaging. Structures in the orbital cavity cannot be identified clearly. Lesion arises from the lacrimal gland, presents with enlarged lacrimal gland with decreased echo-level inside and clear posterior boundary. The extraocular muscle involvement can represent as thickened one or multiple extraocular muscles, including the swelling of the tendon attachment points.
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