Radiographic Procedures II: Sinuses and Orbits PDF

RADIOGRAPHIC PROCEDURES II Sinuses and Orbits Jena Heflin, MBA, RT(R), CMOM Sinuses Air-containing cavities  Sometimes referred to as Paranasal Sinuses  Formed from nasal mucosa Communicate with the nasal fossas  Situated in the frontal, ethmoid, sphenoid, and maxillary bones 1 Sinus Function S...

RADIOGRAPHIC PROCEDURES II Sinuses and Orbits Jena Heflin, MBA, RT(R), CMOM Sinuses Air-containing cavities  Sometimes referred to as Paranasal Sinuses  Formed from nasal mucosa Communicate with the nasal fossas  Situated in the frontal, ethmoid, sphenoid, and maxillary bones 1 Sinus Function Serve as a resonating chamber for the voice  Decrease weight of the skull by containing air  Help to warm and moisten inhaled air  Act as shock absorbers in trauma  Possibly control the immune system  Sinus Development Development starts early in the fetal life  Maxillary Sinuses evident at birth  Frontal & Sphenoid Sinuses develop around age 6 or 7  Ethmoid Sinuses develop during puberty  All sinuses completely develop by age 17 or 18  2 Sinus Divisions Maxillary (2)  Frontal (1 or 2)   Sometimes absent Ethmoid (many)  Sphenoid (1 or 2)  Maxillary Sinuses Largest paranasal sinus  Pyramid in shape  Have three thin walls  Vary considerably in size & shape, but are usually symmetric  Only paranasal sinus NOT found in a cranial bone  Divided into two sinuses by a complete septum  Each sinus divided into subcompartments by a partial septum  3 Maxillary Sinuses  Sinus floor has several elevations corresponding to the roots of the first and second upper molar teeth  Infections can start in the teeth and lead into the maxillary sinus Maxillary Sinuses  Most common paranasal sinus to retain mucus and fluid  Air-Fluid level on x- ray Unique – only sinus to drain upward  Drains into the middle nasal meatus  4 Frontal Sinuses Second largest sinus  Located posterior to the glabella  Rarely symmetric in size and shape  Usually there are 1 or 2, sometimes none  Usually separated by a septum  Drain into the middle nasal meatus  Generally larger in males than in females  Ethmoid Sinuses Contained within the lateral masses of the labyrinths of the ethmoid bone  Number of ethmoid sinuses vary  Divided into 3 main groups:  Anterior Middle Posterior 5 Ethmoid Sinuses  Anterior and Middle Ethmoid Sinuses Each group varies in number from 2 - 8 Drain into the middle nasal meatus  Posterior Ethmoid Sinuses Vary in number from 2 - 6 Drain into the superior nasal meatus Sphenoid Sinuses  Located in the body of the sphenoid bone directly below the sella turcica  Lie between dorsum sellas and the posterior ethmoid air cells Vary in size and shape, usually asymmetric  Usually one or two, but NEVER more than two  Drain into the sphenoethmoidal recess of the nasal cavity  6 Osteomeatal Complex Made up of the drainage pathways between the frontal, maxillary, and ethmoid sinuses  Sinusitis – infection of the sinuses due to obstruction of all or part of the osteomeatal complex  Two key passages:   Infundibulum  Middle Nasal Meatus Osteomeatal Complex 7 Orbits Cone-shaped, bony-walled cavities  Base = rim of the orbit  Apex = posterior portion which corresponds to the optic foramen  Project 30° superiorly from OML  Project 37° away from the MSP  Orbits 8 Orbits  Formed by seven different bones  Cranial Bones  Frontal  Sphenoid  Ethmoid  Facial Bones  Maxilla  Zygoma  Lacrimal  Palatine Orbits  Circumference of Orbit (outer rim):  Frontal  Orbital plate of the frontal bone forms most of the roof of the orbit  Zygoma  Forms the lateral walls  Maxilla  Forms the floor 9 Orbits  Each orbit contains three holes or openings in the posterior portion:  Optic Foramen  Superior Orbital Fissure  Inferior Orbital Fissure Orbits  Optic Foramen  Small hole in the sphenoid bone  Passageway for the Optic Nerve (CN II)  Corresponds to apex of the orbit  Superior Orbital Fissure  Opening between the greater and lesser wing of the sphenoid bone  Located lateral to the optic foramen  Passageway for 4 cranial nerves (CN III - VI) 10 Orbits  Inferior Orbital Fissure  Located between the maxilla, zygomatic bone, and the greater wing of the sphenoid  Passageway for the maxillary branch of the Trigeminal Nerve (CN V)  Sphenoid Strut  Small root of bone separating the superior orbital fissure and the optic canal Orbital Fractures  Blowout Fracture  Common fracture to the orbital floor  Orbit contents “blow out” into the floor of the orbit  Usually caused by blunt trauma  Example – Baseball hitting eye  Seen in athletes, such as boxers or baseball players 11 Blowout Fracture Orbital Fractures  Tripod Fracture   Involves the zygomatic bone and its three connections: 1. Frontal 2. Temporal 3. Maxilla Healing is quite rapid 12 Image Analysis Presentation of radiographs, pertinent anatomy, and positioning criteria. General Considerations    10 x 12 IRs 40-inch SID Sinus view are best performed upright  Demonstrates   air/fluid levels Shield using full lead apron Taken on suspended respiration 13 Sinuses – PA Caldwell Extend pt.’s neck and rest tip of the nose on the bucky OML forms a 15 angle with the CR       A sponge can be used for support MSP  to plane of IR CR exits bridge of the nose (nasion) Collimate to sinuses Sinuses – PA Caldwell Structures Seen    Petrous ridges in the lower 1/3 of the orbit Symmetric petrous ridges Best view to demonstrate frontal sinuses and anterior ethmoid sinuses 14 Sinuses – PA Water’s Method      a.k.a. Parietoacanthial Projection Head titled back & chin resting on bucky OML is 37 degrees with the IR (MML  to bucky) CR exits the acanthion Collimate to sinuses Sinuses – PA Waters Method Structures Seen   Petrous pyramids projected below the floor of the maxillary sinuses Best view to demonstrate maxillary sinuses 15 Sinuses – PA Water’s Open Mouth An Open-Mouth Waters can be performed in which the patient is instructed to open the mouth. In this case, the MML will NOT be  to the IR. In this view, the sphenoidal sinuses will be projected through the open mouth. Sinuses – Lateral Projection       Pt in RAO or LAO position, head it turned lateral MSP is // to IR IOML  to front edge of IR IP line  to IR CR is ½ - 1 inch posterior to outer canthus Collimate to sinuses 16 Sinuses – Lateral Projection Structures Seen    Superimposed orbital roofs and mandibular rami No rotation of sella turcica Demonstrates all sinuses Sinuses – SMV (Submentovertical)        Done on upright bucky Pt’s head is tilted back; vertex rests on upright bucky MSP is  to IR IOML is // to IR CR is  to IOML; CR enters at MSP, passing through sella turcica (3/4” anterior to EAM) Collimate to sinuses 17 Sinuses – SMV (Submentovertical) Structures Seen    Anterior frontal bone superimposed by mental protuberance (chin) Mandibular condyles anterior to petrous pyramids Best view to demonstrate the sphenoid and ethmoid sinuses Orbits – PA Axial CR angled 30 caudal       Some protocols may require a PA Caldwell, which would use a 15 caudal angle Nose and forehead resting on bucky with eyes closed MSP & OML  to IR CR exits center of orbits Collimate closely to orbits 18 Orbits – PA Axial Structures Seen   Petrous pyramids seen below inferior orbital margins Symmetric superior orbital fissures seen between the greater and lesser sphenoid wings Orbits – PA Modified Waters Method      Head tilted back and chin resting on bucky with eyes closed MSP  to IR OML is 50 degrees with the IR CR exits mid-orbits Collimate closely to orbits 19 Orbits – PA Modified Waters Method Structures Seen    Petrous pyramids lie below orbital shadows Symmetric orbits Demonstrates localization of foreign body Best view to demonstrate a blowout fracture Orbits – Lateral Projection       Pt in RAO or LAO position, head is turned lateral with eyes looking straight ahead MSP is // to plane of IR IOML  to edge of IR IP line  to the plane of the IR CR at outer canthus Collimate closely to orbits 20 Orbits – Lateral Projection Structures Seen   Superimposed orbital roofs Demonstrates foreign bodies Perform upright if done for fracture Orbits – Rhese Method       Pt. prone/semi-prone 3-point landing: chin, cheek, and nose touching the table AML  to IR MSP 37° from vertical or 53° from horizontal CR at 1 inch superior and posterior to TEA CR exits mid-orbit on side closest to IR 21 Orbits – Rhese Method Structures Seen  Optic foramen should be seen in the lower outer quadrant of the orbit Radiographic Evaluation for the Rhese Method 22 Critical Thinking What would you do? Situation A radiograph of a Parietoacanthial (Waters) projection reveals that the petrous ridges are projected within the maxillary sinuses. What can be done to correct the positioning of this view? Choice A Choice B The patient’s head needs to be extended more The patient’s head needs to be flexed more 23 Situation A patient with a clinical history of sinusitis comes into the radiology department for a sinus study. The patient is quadriplegic and cannot be placed erect. What projection (with modifications) will best demonstrate any possible air-fluid levels? Correct Answer: Situation A patient enters the emergency department with trauma to his eye. The doctor suspects a blowout fracture and orders an orbit x-ray series. What view and patient position will best demonstrate a blowout fracture? Correct Answer: 24 Assignment See course schedule for reading assignment  Sinuses Worksheet  Entire  worksheet Study positioning notes!!! 25