Overview of Paranasal sinus Radiology.pptx

Anatomy of PNS, Variant anatomy, X-ray imaging and its pathology

1. Overview of Paranasal sinus & Xray Dr. Shailesh rathee PGY-1 Radiodiagnosis

2. Contents 1. Introduction 2. Anatomy – Development, Boundaries, Osteomeatal unit , Drainage of sinuses 3. Variant anatomy 4. Patient preparation 5. General imaging quality guidelines 6. Extra oral landmark for patient positioning 7. Various PNS view positioning and their modification 8. Pathology

3. Introduction The large, air-filled cavities of the paranasal sinus are sometimes called the accessory nasal sinuses because they are lined with mucous membrane, which is continues with nasal cavity. These sinuses are divided into four groups, according to the bones that contain them : Maxillary-maxilla (facial bone) Frontal -frontal (cranial bones) Ethmoid- ethmoid (cranial bones) Sphenoid (cranial bone )

4. Anatomy- Development

5. Anatomy – Frontal sinus Embryologically, the frontal sinuses are anterior ethmoid air cells that grows into frontal bone. Boundaries: Anterior wall – outer table of frontal bone Posterior wall – Inner table of frontal bone Floor – upper part of orbit Medial wall – forms the septum between two frontal sinus Drainage: Drains through the frontal sinus ostium and the frontal recess into the anterior portion of ethmoidal infundibulum. Dimension : Adult sinus is variable in size, averaging 24.3mmX29mmX20.5mm Most common site for Mucocele, osteomyelitis and fistula (patient presenting with early morning headache due to gravity) Most common site for benign tumor i.e. osteoma

6. Anatomy- Maxillary sinus/Antrum of Highmore Boundaries: Anterior wall: facial surface of maxilla and cheek Posterior wall: Infra temporal & pterygopalatine fossa Medial wall: lateral wall of the nasal cavity (Middle & inferior meatuses) This wall is thin and membranous. Laterally: Infratemporal fossa Roof : floor of orbit Floor: Alveolar part of maxilla ( maxillary alveolus Drainage: Via maxillary ostium->Posterior part of ethmoidal infundibulum ->hiatus semilunaris->Middle meatus Average capacity : 14.75 ml(14-15ml) Most common site of sinusitis in adults, Fibrodysplasia (benign), malignant tumor(maxillary carcinoma)

7. Anatomy- Sphenoid sinus Relations: Anterior part : Roof- (floor of sella )Olfactory tract, optic chiasma & frontal lobe Lateral –(ICA) Optic nerve, internal carotid artery & Maxillary nerve Posterior part : Roof- Pituitary gland in sella turcica Lateral – cavernous sinus, ICA & Cranial nerves III,IV,VI & all divisions of V Drainage: S-E recess above superior turbinate Extent: mean 17 mm (measured from ostium to nearest part of sella Pain radiating to occiput in sphenoid sinusitis

8. Anatomy- Ethmoidal sinus Relations: Roof- fovea ethmoidalis of frontal bone and horizontal cribriform plate Lateral wall- orbit (lamina papyracea) Medial wall- lateral surface of middle and superior turbinate Posterior wall- anterior wall of sphenoid Basal lamellae divide into anterior and posterior groups. Drainage: -Anterior- recess of hiatus semilunaris -Middle meatus – via ethmoid bulla Posterior – Via superior meatus and spehnoethmoidal recess Most common site of sinusitis in children (Pain on eye movement) Most common site for adeno carcinoma

9. Anatomy- OSTEOMEATAL Unit -The ostiomeatal unit(OMU) is a common channel that links the frontal sinus, anterior ethmoidal cells and maxillary sinus to the middle meatus, allowing airflow and mucociliary drainage. - Ostiomeatal unit parts(5): 1. Ostium of maxillary sinus 2. Infundibulum 3. Hiatus semilunaris 4. Bulla ethmoidalis (BE) (largest ethmoidal air cell) 5. Uncinate process -Drainage: Superior meatus – Posterior ethmoid Middle meatus – frontal/anterior ethmoidal/maxillary Inferior meatus – Nasolacrimal duct S-E Recess – sphenoid sinus

10. Variant anatomy - Pneumatization variants- Middle turbinate 1. Paradoxical middle turbinate: Abnormal inward rotation of middle turbinate. Occasionally DNS with bony spur may affect sinus outflow tract. 2. Concha bullosa: Ethmoid air cells may pneumatize the middle turbinate Large concha bullosa may push uncinate process laterally narrowing OMU.

11. Variant anatomy - Pneumatization variants- Ethmoidal cells 2. Ethmoidal air cell variants: Ethmoidal air cells may pneumatize surrounding bones to produce variant anatomy -Anterior ethmoidal cell: agger nasi cells(Recurrent frontal sinusitis), haller cells(recurrent maxillary sinusitis)(infraorbital), frontal cell(Migrate into frontal recess) -Posterior ethmoidal cell( sphenoethmoidal cells): ondi cells(optic nerve compression)(Double floor /cruciform appearance)

12. Variant anatomy- Pneumatization variants- frontal cells (Kuhn’s cells) Located directly above the agger nasi cells Four types : I : Single II : two or more III : single but large and bulges into frontal sinus IV : located completely within the frontal sinus “cells within cell”

13. Variant anatomy - Pneumatization variants- Sphenoid sinus and others 3. Sphenoid sinus: ( Hammer and Radberg classification for sphenoid pneumatization ) (A) Conchal type: pre dominantly non pneumatize sphenoid bone (children) (B) Presellar type : extending up to anterior wall of the sella turcica (C) Sellar type : Entire sphenoid body and behind sella turcica pneumatize ,so that the pituitary forms a distinct bulge in its posterosuperior wall (adults) 4. Interlameller cell of graunwald : vertical lamella of the middle turbinate pneumatized 5. Supreme/superior turbinate: paradoxically curved superior turbinate 6. Maxillary sinus: Partial or complete septations

14. Anterior ethmoidal artery Branch of Ophthalmic artery supplying PNS, nasal septum and lateral nasal wall Anterior ethmoidal notch can be identified bilaterally in 95-100 % cases If notch abuts fovea ethmoidalis or lateral lamella- Safe during FESS Supra orbital pneumatization of ethmoid air cells above anterior ethmoidal notch- Increased risk of injury during FESS.

15. Variant anatomy -Uncinate process attaches to lamina papyracea/skull base/middle turbinate/ -Isolated frontal sinus agenesis (common) -Accessory ostia of the maxillary sinus -Sphenoid sinus septa attachment on the bony canal of optic nerve - Total paranasal sinus agenesis(rare), - Dehiscent infraorbital canal Anteroposterior X-ray of the skull showing hypoplastic frontal sinuses and mild nasal septum deviation

16. Patient preparation - Before undertaking PNS radiography, the following specific considerations should be made -Ensure that all metal objects are removed from the patient , e.g. nose pin, hair clips and hairpins -Bunches of hair often produce artefacts and thus should be untied. -If the area of interest includes the mouth, then false teeth containing metal and metal dental bridges should be removed -The patient should be provided with a clear explanation of any movements and film positions associated with the normal operation of the skull unit.

17. General image quality guidelines - Images should have a visually sharp reproduction of all structures such as outer and inner lamina of the cranial vault, the trabecular structure of the cranium, the various sinuses and sutures where visible, vascular channels, petrous part of the temporal bone and the pituitary fossa. A 400 (regular) speed imaging system is recommended (regular conventional film/screen combination). Whenever possible, use an occipito -frontal ( postero -anterior) rather than a fronto -occipital (antero-posterior) technique, since this vastly reduces the dose to the eyes. 24 – 30 cm cassettes are generally used for plain skull radiography.

18. Extraoral landmarks for patient positioning- The median plane of the head (Midsagittal plane): This is determined by a line that is coincident with the sagittal suture between the upper margins of the parietal bones running from the top of the skull backwards. - In the lateral views the median plane is kept parallel with the cassette. - In the postero -anterior views, it is kept at right angles with the film cassettes.

19. Extraoral landmarks for patient positioning - The Orbitomeatal line ( Canthomeatal line): -This is an imaginary line from the outer canthus of the eye to the tragus of the ear. -This is known as the radiographic base line.

20. Extraoral landmarks for patient positioning - The Frankfort Horizontal line Is the line which runs from the most inferior portion of infraorbital margin of the orbit to the highest point on the superior surface of the external auditory meatus.

21. PNS VIEWS PROJECTION/MODIFICATIONS STRUCTURES VISUALISED BEST VISUALISED OCCIPITOFRONTAL/ POSTEROANTERIOR VIEW GRANGER PROJECTION CALDWELL VIEW Frontal bone, frontal sinus, ethmoid sinus, orbits, sphenoid wings, petrous ridges, and internal auditory canals. FRONTAL SINUS PUFFED CHEEK VIEW FOR SIALOLITHS OCCIPITOMENTAL/ NOSE TO CHIN VIEW WATER’S VIEW (0DEGREE) Maxillary sinuses, ethmoid sinuses, frontal sinuses, orbits, and zygomatic arches. PIERRE’S VIEW/MODIFIED WATERS VIEW(OPEN MOUTH) Sphenoidal sinuses can be seen if the patient is asked to open the mouth, whereby sphenoidal sinuses are projected on the palate. MAXILLARY SINUS Walls of maxillary sinus, orbit, zygomatic arch,nasal and mandible deviation BREGMA MENTON VIEW LATERAL VIEW Maxilla, hard palate, maxillary sinus, ethmoid sinus, sphenoid sinus, frontal sinus, and orbits. ALL SINUS CAN BE SEEN LATERAL OBLIQUE(RHESE’S VIEW) ETHMOID SINUS BASE SKULL VIEW/SUBMENTO-VERTICAL( Hitz view) SPHENOID SINUS

22. Lateral view Patient Position: Semiprone . Part Position: Head is in true lateral position against the bucky. The infraorbital meatal line is parallel with the long edge of the cassette, and the interpupillary line is perpendicular. Breathing Instructions: Suspended expiration. Common Pitfalls: Head rotation: Must be parallel to the film for proper demonstration.

23. Lateral view- All sinuses can be seen

24. Postero anterior (granger projection) Position of patient : Prone or upright. ; Midsagittal plane should be vertical and perpendicular to the plane of cassette. Radiographic baseline is at 90 degree to film. Only forehead and nose touches the cassette. Part Position: Frontal bone in contact with the bucky.Remove all lateral head tilt and rotation. The orbitomeatal line should be perpendicular to the cassette. Head Position : The patient faces the cassette, the forehead and the nose both touching the cassette (mid-sagittal plane perpendicular to the plane of cassette )

25. Caldwell view Position of patient & Part Position: Same as Granger projection. Measure: Through the CR(Central ray) directed 23 degree to the canthomeatal line entering skull about 3cm above the external occipital protuberance and exiting at the glabella. Tube Tilt: 15Åã caudad. Breathing Instructions: Suspended expiration. Common Pitfalls: 1. Head position: Failure to tuck chin impairs depiction of the orbits. 2.Artifacts: Removal of hair jewellery and eyeglasses is essential.

26. Modification of pa view: Caldwell view Best seen: Frontal sinus Offers better visualization of orbits and ethmoid air cells. Maxillary sinus are superimposed by dense shadow of petrosae .

27. Puffed cheek view Sialoliths in the distal portion of Stensen's duct or in the parotid gland are difficult to demonstrate by intraoral views. However, a PA skull projection with the cheeks puffed out may move the image of the sialolith free of the adjacent bone, rendering it visible on the projected image. Puffed cheek radiograph and its inverted image depicting the calcifications noted within the lesion

28. Occipitomental view/Modified waters view/pierre’s view positioning Patient Position: Prone or upright (PA) Part Position: Midline, with no lateral head tilt or rotation. The head is extended such that the canthomeatal line is elevated 37Åã relative to the CR. Breathing Instructions: Suspended expiration. Common Pitfalls: 1. Mouth position: If the mouth is closed the sphenoid sinus will be obscured. 2. Neck extension: If unable to extend the head, compensate by tube tilt, otherwise the sphenoid sinus will not be seen.

29. Occipitomental view/Modified waters view/pierre’s view(OM with mouth open)/Nose to chin position Best seen: Maxillary sinus; Not seen-posterior ethmoidal Standard occipitomental projection (0 degree Open mouth) Modified occipitomental projection (30 degree OM)

30. Steps of interpretation - Occipitomental view- Step 1: Evaluate the calvarium and sutures starting in the left temporal area over the supraorbital to the right temporal area. Look for intracranial calcification. Step 2: Evaluate the orbits and the frontal sinuses. -Identify the supraorbital and infraorbital rim, the inferior orbital foramen, the floor of the orbit, the zygomaticofrontal sutures and the innominate of the infratemporal fossa crossing on the lateral aspect of each orbit. Step 3: Evaluate the maxillary sinuses & nasal cavity. Identify the superior, medial & lateral walls of the maxillary sinuses; the nasal septum & the floor & lateral walls of nasal cavity. Step 4: Evaluate the zygomatic arches. Identify the frontal, maxillary and temporal processes of the zygoma and zygomaticofrontal suture. Step 5: Evaluate the condylar and coronoid processes of the mandible.

31. Frontal sinus – pathology and clinicoradiologic correlation 1. Congenital : Frontal sinus agenesis 2. Trauma: Frontal bone fractures, Fistula 3. Inflammatory : Frontal sinusitis , mucocele, Osteomyelitis, Fistula 4. Tumor: Frontal sinus osteoma

32. Frontal sinus – pathology and clinicoradiologic correlation Anteroposterior X-ray of the skull showing hypoplastic frontal sinuses and mild nasal septum deviation.

33. Frontal sinus – pathology and clinicoradiologic correlation PA Caldwell’s Skull, Frontal bone fracture. -The fracture is visible as multiple radiolucent lines. -The sinus is filled with hematoma (arrow)

34. Frontal sinus – pathology and clinicoradiologic correlation Chronic Maxillofrontal Sinusitis View: -Gas-fluid levels (red arrows), indicating acute sinusitis. Mucosal thickening of the maxillary sinuses (blue arrows), suggestive of chronic sinusitis. 

35. Frontal sinus – pathology and clinicoradiologic correlation Frontal Sinus Osteoma. Dense, ivory-like New bone fills a frontal sinus. Non-homogeneous lucent and sclerotic to predominantly fine, bony ground-glass appearance

36. Frontal sinus – pathology and clinicoradiologic correlation

37. Maxillary sinus- pathology and clinicoradiologic correlation Maxillary sinus disease can be divided into: Intrinsic disease : (1) Inflammatory disease - Mucositis, sinusitis, mucosal retention pseudocyst, polyps, antrolith , mucocele. (2) Benign neoplasm – papilloma, osteoma (3) Malignant neoplasm – squamous cell carcinoma, pseudotumor (B) Extrinsic disease : (1) Inflammatory disease - Periostitis

38. Maxillary sinus- pathology and clinicoradiologic correlation Mucositis: -Thickened mucosa -Non- corticated band more radiopaque than the air filled sinus, paralleling the bony wall of sinus

39. Maxillary sinus- pathology and clinicoradiologic correlation – Sinusitis - Criteria considered in water’s view :(According to veterans affairs general medicine clinic study) (1)Presence of air fluid level , (2)Sinus opacity, (3)Mucosal thickening greater than 3 mm in maxillary sinus, 2mm in ethmoidal sinuses, any thickening in frontal & sphenoidal sinuses -Appearance of thickened mucosa helps to differentiate between allergic reaction(Lobulated mucosa) and an infection (Smooth mucosal outline with contour following Sinus wall)

40. Maxillary sinus- pathology and clinicoradiologic correlation – Sinusitis -The resolution of acute sinusitis becomes apparent on radiograph as a gradual increase in the radiolucency of the sinus -The thickened mucosa gradually shrinks In time it again becomes radiographically invisible -In chronic sinusitis the inflammation may stimulate the sinus periosteum to produce bone resulting in thick sclerotic borders of the maxillary antrum - Lund-Mackay staging(CT): Stage 0: No abnormality Stage 1: Partial opacification Stage 2: Total opacification

41. Maxillary sinus- pathology and clinicoradiologic correlation- Retention pseudocyst Well defined, non corticated, smooth, dome shaped, homogenous radiopaque mass. Cysts usually found projecting from the floor of the sinus , though some form on lateral walls. Base maybe narrow or broad Dodd and Jing – Mucous cysts are more likely to have a broad base, serous more pedunculated Mucous cyst smaller than serous cyst Mucous cyst associated with thickened mucosa.

42. Maxillary sinus- pathology and clinicoradiologic correlation- Antrolith Deposition of mineral salts -> Calcium phosphate, carbonate, magnesium -> Nidus -> Antrolith Radiographic features: Location : maxillary sinus Edge: Well defined/smooth or irregular Shape: Round, ovoid Internal: Radiopaque, may have a “laminated” appearance with radiopaque and radiolucent bands evident due to continues layering down of calcium salts.

43. Maxillary sinus- pathology and clinicoradiologic correlation- Mucocele Intra antral/intra nasal inflammation/polyp/neoplasm->Blockage of sinus ostium->Mucocele

44. Facial bones on OM and OM 30 Views

45. Le fort fracture

46. Campbell’s and trapnell’s lines 4" line:- Runs across the right ramus of the mandible, line of the occlusal plane, left ramus of the mandible. 5" line:- ( trapnell’s line) Runs along the inferior border of the mandible from right angle to left angle.

47. Tripod fracture 1 - The zygoma (asterisk) is separated from the frontal bone at the zygomatico -frontal suture 2 - Comminated fracture of the zygomatic arch 3 - Orbital floor fracture 4 - Breach of the lateral wall of the maxillary antrum

48. Tripod fracture A 'tripod' fracture has 4 visible components - not always all visible 1 - Orbital floor fracture 2 - Fracture of the lateral wall of the maxillary antrum 3 - Zygomatic arch fracture 4 - Widening of the zygomatico -frontal suture Increased density of the maxillary antrum is due to it filling with blood Face - Tripod fracture - OM view Face - Tripod fracture - OM30 view The zygomatico -frontal suture (asterisk) appears relatively normal on this image and looks similar to the contralateral side A slightly wide zygomatico -frontal suture should not be taken as significant unless accompanied by other evidence of injury on the same side

49. Isolated zygomatic arch fracture Disruption of the middle McGrigor -Campbell line is due to a comminated fracture of the right zygomatic arch. Following the upper and lower lines shows no F racture

50. Isolated zygomatic arch fracture Zygomatic arch fracture - OM view Zygomatic arch fracture - OM30 view Look for the 'elephant's trunk' appearance of the zygomatic arch Comparing the symptomatic side with the asymptomatic side can help reveal an abnormal contour of the zygomatic arch The zygomatic arch fracture is more easily seen on the OM30 ( Occipito -Mental 30°) imageOn the left (the non-injured side) overlying structures give the impression of a fracture, but careful scrutiny shows the cortex is intact

51. CASE: Blunt trauma L side of the face 26y/M Blunt injury in field area Pain, swelling around L eye Vision preserved, restricted eye movements No field defects

52. Blowout Fracture/Trap door fracture Blowout fracture - OM view Blowout fracture - OM 30 view Blowout fractures are caused by increased pressure in the orbit - the orbit gives way at its weakest point, which is the orbital floor The classic 'teardrop' sign is due to herniation of soft tissue into the maxillary antrum The air/fluid level in the maxillary antrum is due to the presence of blood

53. Take home message!! Although investigation of choice/gold standard investigation for most PNS anomalies remains HRCT/FESS/MRI but x-ray plays a vital role as for its cost effectiveness, easy availability and in cases where CT scan are contraindicated.

54. References 1. Yochum TR, Rowe LJ. Yochum and Rowe’s Essentials of Skeletal Radiology. 2. Whitley AS, Jefferson G, Holmes K, Sloane C, Anderson C, Hoadley G. Clark’s Positioning in Radiography 13E [Internet]. CRC Press eBooks. 2015. Available from: https:// doi.org /10.1201/b13534 3. Watkinson JC, Clarke RW. Scott-Brown’s Otorhinolaryngology and Head and Neck Surgery, Eighth Edition: 3 volume set. CRC Press;

55. Thank you