Radiography of the Orbits Ballinger Frank 1999 pg

Radiography of the Orbits Ballinger & Frank, 1999, pg 291

Function of Orbits n Serve as bony sockets for the eyeballs n Openings for nerves and blood vessels

Division of the Orbits n Roof n n Floor n n Primarily composed of -orbital plate of frontal bone Zygoma (small amount) Maxilla Palatine Two Walls n Medial n n Lacrimal Lateral n Zygoma (large amount)

Bones of the Orbits - 7

Base of the Orbit n The circumference n n or circular base Made of 3 bones n Frontal (cranial bone) n n n Maxilla ( facial bone) n n Orbital plate Forms most of the roof Helps form the floor Zygoma (facial bone) n Forms part of the lateral wall and some of the floor

Openings in Posterior Orbit n Optic Foramen n n Optic canal Sphenoid strut Superior Orbital Fissure Inferior Orbital Fissure

ANGLE OF ORBITS n Each orbit projects n n 30 degrees superiorly 37 degrees toward MSP

Indications for Orbit and Eye Radiography n Possible Fractures n Foreign body of the eye

Mechanisms producing Orbital Fractures n Auto accidents n Assault n Falls, sports, and industrial accidents

Blowout Fracture n n Blow to the eye Orbital floor is fractured Soft tissue herniates into maxillary sinuses Often have ocular injury Ponsell, 2003

Tripod Fracture n n n Direct blow to zygoma Visual concave abnormalities Usually orbits are involved Ponsell, 2003

Le. Fort Fractures Le. Fort types II and III involve the orbits Richardson, 2000

Le. Fort Fractures n Type 3 n Separation of mid third of face at zygomaticotemporal, nasofrontal sutures, and across orbital floors n Complications n Non-union n Malocclusion n Lenthening of mid face n Lacrimal system obstruction

Le. Fort Fractures n Type II n Complications n n Separation through frontal processes, lacrimal bones, orbit floors, zygomaticomaxillary suture line, lateral wall of maxillary sinuses, and pterygoid n Lacrimal system obstruction Infraorbital nerve anesthesia n Diplopia n malocclusion

Basic and Special Projections n Orbits n Basic n n n Parietoorbital (Rhese Method) Parietoacanthial (Waters method) Special n Modified Parietoacanthial (Modified Waters method) n Eyes n Basic n Lateral n PA Axial n Modified Parietoacanthial (Modified Waters method)

Parietoacanthial Projection Waters Method n n n Tip of extended chin on grid device OML 37 degrees from plane of cassette MSP perpendicular to cassette MML perpendicular to cassette CR exits acanthion Ballinger & Frank, 1999, pg 317

Parietoacanthial Projection Waters Method Radiograph n n Distance from lateral border of skull and orbit equal on each side Petrous ridges projected immediately below maxillary sinuses

Modified Parietoacanthial Projection Modified Waters n n n OML 55 degree angle from plane of IR MSP perp CR perpendicular and exits acanthion

Modified Parietoacanthial Projection Modified Waters Radiographs n n Petrous ridges projected immediately below the inferior border of the orbits Equal distance from lateral orbit to lateral skull on both sides

Modified Parietoacanthial Projection Modified Waters method

Modified Waters Radiograph & Diagram

Acanthioparietal Projection Reverse Waters Method n n Patients chin up and neck adjusted so the OML is 37 degrees from cassette MML perpendicular to cassette MSP perpendicular to cassette CR enters acanthion Ballinger & Frank, 1999, pg 320

Reverse Waters Radiograph n n Distance from lateral border of skull and orbit equal on each side Petrous ridges projected immediately below maxillary sinuses

Parietoorbital Projection Rhese Method (PA) Optic Canal and Foramen n 3 point landing n n n Zygoma, nose, and chin AML perpendicular to cassette MSP forms a 53 degrees angle from cassette PA- CR enters 1”superior and posterior to TEA PA- CR exits through the affected orbit Ballinger & Frank, 1999, pg 290

n Parietoorbital Projection Rhese Method (PA) Optic Canal and Foramen Radiograph Optic canal & foramen visible at end of sphenoid ridge in inferior & lateral quadrant of orbit n Entire orbital rim n Supraorbital margins lying in same horizontal plane n Close beam restriction to the orbital region

Rhese Method (AP) Optic Canal and Foramen n 3 point landing n Zygoma, nose, and chin n AML perpendicular to cassette n MSP forms a 53 degrees to cassette n AP- CR enters uppermost orbit at inferior lateral quadrant Ballinger & Frank, 1999, pg 292

Rhese Method (AP) Optic Canal and Foramen Radiograph n Optic canal & foramen visible at end of sphenoid ridge in inferior & lateral quadrant of orbit n Entire orbital rim n Supraorbital margins lying in same horizontal plane n Close beam restriction top the orbital region

Rhese Radiograph and Diagram

Foreign objects in the EYE

Lateral Projection (EYE) n Use non-grid high resolution technique n Semiprone or seated upright n Affected eye closest to cassette n MSP parallel with plane of IR n Instruct pt to look straight ahead n IPL perpendicular to IR n CR: Perp through outer canthus

Lateral Eye for Foreign Body n Density & contrast permitting optimal visibility of orb it and foreign bodies n SI orbital roofs n Close beam restriction

n n n Non-grid high resolution technique Forehead & nose on IR. Center IR ¾ “ distal to nasion MSP & OML perp Eyes closed & held still CR: Through center of orbits, 30 degrees caudal PA Axial (EYE)

PA Axial Eye Radiograph n Petrous pyramids lying below orbital shadows n No rotation of cranium n Close beam restriction

Modified Waters (EYE) n IR at level of orbits n Rest pt’s chin on IR n n n MSP perp and OML 50 degrees from IR CR: Perp through midorbits Instruct pt to close eyes and hold eyes still

Modified Waters Radiograph n n n Petrous Pyramids lying well below orbital shadows Symmetric visualization of orbits Close beam restriction

LETS REVIEW

Seven Bones of the Orbit

Seven Bones of the Orbit n n n n A. Frontal bone- orbital plate B. Sphenoid bone C. Palatine bone D. Zygomatic bone E. Maxillary bone F. Ethmoid bone G. Lacrimal bone

Openings and Supporting Structures of Openings of the Orbit

Openings and Supporting Structures of Openings of the Orbit n A. Optic Foramen n B. Sphenoid Strut n n C. Superior Orbital Fissure D. Inferior Orbital Fissure

Parietoorbital Oblique Projection of Orbits

Parietoorbital Oblique Projection of Orbits n n A. Frontal bone- orbital plate B. Sphenoid bone C. Optic foramen & canal D. Superior orbital fissure n n E. Inferior orbital fissure F. Sphenoid strut G. Lateral orbital margin H. Superior orbital margin

Orbital anatomy Review n http: //www. uth. tmc. edu/radiology/test/er _primer/face/images/wtrs 02. html

References Ballinger, P. W. & Frank, E. D. (1999). Merrill’s atlas of radiographic positions and radiologic procedures. V 2. New York: Mosby Ponsell, M. R. (2003). Assessing facial fractures in the emergency room. New Jersey Richardson, M. L. (2000). Facial and mandibular fractures. Retrieved May 5, 2007 from: http//www. rad. washington. edu/mskbook/facialfx. html