1. 1. Paranasal sinuses Presented by: Dr. Bharath Jain 1st year radiology PG SSIMS& RC
2. 2. Nasal cavity Nasal cavity extends from the palate to the skull base and is divided by nasal septum. It opens posteriorly via choana in to nasopharynx. Nasal septum comprises the septal cartilage anteriorly and perpendicular plate of ethmoid and vomer posteriorly.
3. 3. Sinuses Air containing cavity in certain skull bones Develop as a diverticula/outpouching from the lat wall of nose & extend into Maxilla, Ethmoid, sphenoid and frontal bones. Each sinuses have orifices that open into the meatus, covered by turbinates.
4. 4. Sinuses Status at birth 1st radiological evidence Adult size reached at Maxillary sinus Present at birth 4-5 months after birth 15years Ethmoid sinus Present at birth 1year 15years Sphenoid sinus Not present 4year 12years Frontal sinus Not present 6year 18-19years
5. 5. Frontal sinuses.
6. 6. Frontal recess The frontal recess is an hourglass like narrowing between the frontal sinus and the anterior middle meatus through which the frontal sinus drains The frontal recesses are the narrowest anterior air channels and are common sites of inflammation. Their obstruction subsequently results in loss of ventilation and mucociliary clearance of the frontal sinus
7. 7. Maxillary sinus Its the first sinus to form and is hypoplastic in 10% of people. The roof forms the orbital floor and floor is formed by the maxillary alveolus. Its medial wall forms the lateral wall of nasal cavity. Its drains in to middle meatus via the infundibulum.
8. 8. Osteomeatal unit: It drains the frontal, anterior ethmoid and maxillary sinuses. It includes maxillary sinus ostium, ethmoid infundibulum, hiatus semilunaris and frontal recess. It is best demonstrated on coronal CT.
9. 9. The OMC is bounded medially by the middle turbinate, posteriorly and superiorly by the basal lamella, and laterally by the lamina papyracea. Inferiorly and anteriorly the OMC is open.
10. 10. Sphenoid sinus Sphenoid sinus develops in the body of the sphenoid sinus and drains via a sinus ostium into spheno ethmoid recess. The degree of pneumatisation is variable and may extend into greater and lesser wing of sphenoid and pterygoid plates. There are many important structures in relation to sphenoid sinus like vidian canal, optic nerve and foramen rotundum.
11. 11. Ethmoid air cells Thin walled air cavities in the lateral masses of the ethmoid bone. Varies from 3 18 in number. Clinically divided into anterior ethmoidal air cells & posterior ethmoidal air cells, by basal lamella (lateral attachment of middle turbinate to lamina papyracea) Anterior drain into- Middle meatus. Posterior- sup.meatus & spenethmoidal recess.
12. 12. Anatomical variants
13. 13. Paradoxic Curvature Normally, the convexity of the middle turbinate bone is directed medially, toward the nasal septum. When paradoxically curved, the convexity of the bone is directed laterally toward the lateral sinus wall. The inferior edge of the middle turbinate may assume various shapes, which may narrow and/or obstruct the nasal cavity, infundibulum, and middle meatus.
14. 14. Concha Bullosa It is an aerated turbinate, most often the middle turbinate. When the pneumatization involves the bulbous segment of the middle turbinate, the term concha bullosa applies. If only the attachment portion of the middle turbinate is pneumatized, and the pneumatisation does not extend into the bulbous segment, it is known as a lamellar concha.
15. 15. Agger Nasi Air Cell Its an ethmoturbinal remnant present in nearly all patients. Located anterior to the vertical attachment of the middle turbinate to the skull base. The degree of ANC pneumatization varies and has a significant effect on both the size of the frontal sinus ostium and the shape of the recess.
16. 16. Fronto-ethmoid/kunh cells/bulla frontalis Are the anterior ethmoid cells which invade the frontal bone, bulging its floor. They are more easily demonstrated at sagittal view, where they appear as ethmoid air cells located above the ethmoid bulla and as an extension towards the frontal sinus. Depending on their size and pneumatization extent, such cells may affect the frontal sinus drainage.
17. 17. These air cells, are categorized into four types depending on their number and degree of extension into the frontal sinus. They are all located superior to the ANC.
18. 18. Type 1 (most common): Single cell superior to the ANC that does not extend into the frontal sinus Type 2: Two or more cells superior to the ANC that may or may not extend into the frontal sinus. Type 3: Single frontal cell superior to the ANC that extends into the frontal sinus. Type 4: Completely contained in the frontal sinus. This configuration is rare.
19. 19. Haller cell These are ethmoid air cells located anterior to the ethmoid bulla, along the orbital floor, adjacent to the natural ostium of the maxillary sinus, which may cause mucociliary drainage obstruction, predisposing to the development of sinusitis.
20. 20. Sphenoethmoid cell (Onodi cell) This is formed by lateral and posterior pneumatization of the most posterior ethmoid cells over the sphenoid sinus. The presence of Onodi cells increases the chance that the optic nerve and / or carotid artery would be exposed in the pneumatized cell.
21. 21. Accessory maxillary ostia Accessory maxillary ostia are generally solitary, but occasionally may be multiple. Such variation may be congenital or secondary to sinusal diseases. Possible mechanisms involved in the development of such variation include: main ostium obstruction, maxillary sinusitis or anatomical/pathological factors in the middle meatus, resulting in rupture of membranous areas.
22. 22. Variations in uncinate process
23. 23. Imaging modalities
24. 24. X RAY CT MRI
25. 25. X ray Waters view & caldwell view. CT gold standard. Coronal & axial sections. MRI is predominantly used for pre and post operative management of naso sinus malignancy. The chief disadvantage of MRI is its inability to show the bony details of the sinuses, as both air and bone give no signal.
26. 26. Parietoacanthial projection: waters view
27. 27. Part Position: Extend neck, placing chin and nose against table/upright Bucky surface. Head is adjusted so as to bring the orbito meatal line to a 45 degree angle to the casette holder. Position the median saggital plane is perpendicular to the midline of grid or table/upright bucky surface. Ensure that no rotation or tilt exists. Centering is done at acanthion.
28. 28. Waters view
29. 29. Caldwell Part Position: Place patient's nose and forehead against upright Bucky or table with neck extended to elevate the OML 15 from horizontal. A radiolucent support between forehead and upright Bucky or table may be used to maintain this position.(alternate method if Bucky can be tilted 15.) Align MSP perpendicular to midline of grid or upright Bucky surface. Centering is done at nasion, ensuring no rotation.
30. 30. PA PROJECTION: SINUSES Caldwell Method
31. 31. 1
32. 32. Parietoacanthial transoral projection: Open Mouth Waters Method
33. 33. CT procedures and techniques CT is currently the modality of choice in the evaluation of the paranasal sinuses and adjacent structures. Its ability to optimally display bone, soft tissue, and air provides an accurate depiction of both the anatomy and the extent of disease in and around the paranasal sinuses. In contrast to standard radiographs, CT clearly shows the fine bony anatomy of the osteomeatal channels.
34. 34. SCAN LIMITS : From the ant margin of frontal sinus to post margin of sphenoid sinus
35. 35. Coronal section procedure
36. 36. Axial plane Axial images complement the coronal study, particularly when there is severe disease (opacification) of any of the paranasal sinuses and surgical treatment is contemplated. Axial images are particularly important in visualizing the frontoethmoid junction and the sphenoethmoid recess.
37. 37. Contrast CT Contrast is not required for all cases of CT paranasal sinus. Used in cases such as vascular lesion, malignancy, mass extending intra cranially, acute infections.
38. 38. MRI is helpful in knowing intrcranial or intraorbital extension.
39. 39. The real value of unenhanced CT is the following: if you see an opacified sinus with hyperdense contents, it is usually a sign of benign disease. Tumor is not hyper-dense. The hyperdensity is due to one or a combination of the following: Inspissated secretions Fungus Blood
40. 40. Sinusitis Sinusitis is the inflammatory condition of the mucous membrane lining of the sinuses. It may progress to pus formation. Sinusitis may be acute and chronic.
41. 41. Sinusitis may divided into: Rhinogenous infection spreads from the nasal cavity. It is the most common way for infection and such sinusitis is the complication of the flu. Odontogenic infection spreads from upper teeth. This way is typical only for maxillary sinus. The pathologic process may spreads from 4,5,6 cheek-teeth apex to the inferior wall of the maxillary sinus Traumatic Hematogenic Allergic.
42. 42. Acute sinusitis It is an acute inflammation of the nasal and paranasal sinus mucosa that last less than four weeks and can occur in any of the paranasal sinuses. It usually follows viral infection. X-ray:Opacification of the sinuses and air/fluid level best seen in maxillary sinus.
43. 43. CT Better anatomical delineation and assessment of inflammation extension, causes and complications. Peripheral mucosal thickening, air/fluid level, air bubbles within the fluid and obstruction of the OMC are recognised findings.
44. 44. Chronic sinusitis Chronic sinusitis refers to on going long term sinus infection- inflammation that often develops secondary to prolonged or refractory acute sinus infection. Allergic and fungal sinusitis tend to be usually symmetrical and involve nasal fossa as well as sinuses. Bacterial sinusitis involves only single or group of contiguous sinuses. Polyps are more common in allergic rather than infected patients.
45. 45. Fungal diseases Invasivse fungal sinusitis: -Acute/chronic/chronic granulomatus Non invasive fungal sinusitis:
46. 46. Acute invasive fungal sinusitis It is a rapidly progressing infection seen predominantly in immunocompromised patients and patients with poorly controlled diabetes. The disease tends to be more rapidly progressing with relatively high mortality and morbidity. Noncontrast CT demonstrates hypoattenuating mucosal thickening or an area of soft-tissue attenuation within the lumen of the involved paranasal sinus and nasal cavity
47. 47. Aggressive bone destruction of the sinus walls occurs rapidly with intracranial and intraorbital extension of the inflammation. These fungi tend to extend along the vessels, and extension beyond the sinuses may occur with intact bony walls. CT is better to assess for bone changes, MR imaging is superior in evaluating intracranial and intraorbital extension of the disease.
48. 48. Chronic invasive fungal sinusitis Inhaled fungal organisms are deposited in the nasal passageways and paranasal sinuses. Insidious progression occurs over several months to years in which fungal organisms invade the mucosa, submucosa, blood vessels, and bony walls of the paranasal sinuses. Individuals are usually immunocompetent.
49. 49. A hyperattenuating soft-tissue collection is seen at noncontrast CT within one or more of the paranasal sinuses. Mottled lucencies or irregular bone destruction may be seen in the paranasal sinuses There may also be sclerotic changes in the bony walls of the affected sinuses representing chronic sinus disease . Infiltration of the periantral soft tissues about the maxillary sinus is an indicator of invasive disease
50. 50. Allergic fungal sinusitis It is the most common form of fungal sinusitis. It is particularly common in warm, humid climates. cause is thought to be a hypersensitivity reaction to certain inhaled fungal organisms
51. 51. Imaging There is usually involvement of multiple sinuses. Disease tends to be bilateral, and there is a frequent nasal component. The majority of the sinuses show near-complete opacification and are expanded. Noncontrast CT demonstrates hyperattenuating allergic mucin within the lumen of the paranasal sinus.
52. 52. Mycetoma- Fungus ball Its usually due to deficient mucociliary clearance mechanism in which fungal organisms deposited in the paranasal sinuses are inadequately cleared. Its common in older individuals. The fungus ball represents a tangled collection of fungal hyphae in the absence of allergic mucin.
53. 53. Fungus ball appears as a mass within the lumen of a paranasal sinus and is usually limited to one sinus. The maxillary sinus is the most commonly involved sinus. A fungus ball typically appears hyperattenuating at noncontrast CT due to dense matted fungal hyphae and may demonstrate punctate calcifications
54. 54. Sino nasal polyposis Polyps are soft tissue pedunculated masses of oedematous hyperplastic mucosa lining the nasal cavity and sinuses. These are benign mucosal lesions. Commonest sites in order of frequency are: Ethmoids >>Maxillary > Sphenoids
55. 55. X ray: Opacification of nasal cavity and sinuses. Hypodense polypoidal,rounded masses in the nasal cavity and paranasal sinuses enlarging sinus ostium . Expansion of the sinus, thining of sinus walls, nasal and ethmoid septa. Widening of the infundibulum.
56. 56. Antrochoanal polyp Benign antral polyp which widens the sinus ostium and extends into nasal cavity;5% of all nasal polyps. Features: -Well defined mass with mucin density arising within maxillary sinus. -Smooth mass enlarging the sinus ostium -No sinus expansion.
57. 57. Mucocele Mucoceles are benign, locally expansile paranasal sinus masses most commonly found in the frontal sinus. Secondary to obstruction of the sinus ostia, there is accumulation of fluid within a mucoperiosteal lined cavity, resulting in erosion and remodelling of the surrounding bone. The most common causes of mucoceles are chronic infection, allergic sinonasal disease, trauma and previous surgery.
58. 58. The most common location of a mucocele is the fronto-ethmoidal sinus, followed by the sphenoid sinus. The least common location is the maxillary sinus. X-ray: will show an expansion of the sinus cavity with loss of the scalloped margin of the normal sinus.
59. 59. Soft tissue density mass- having mucoid (15HU) attenuation. Sinus cavity expansion. Bone remodeling at late stage but no bone destruction Surrounding zone of bone sclerosis/calcification of edges of mucocele(ch sinusitis).
60. 60. Protrusion into orbit displacing medial rectus muscle laterally. Expansion into subarachnoid space. resulting in CSF leaking.
61. 61. Neoplastic diseases Papillomas Carcinomas Olfactory neuroblastoma. Lymphoma
62. 62. InvertedPapilloma Occur in middle aged man. They arise from lateral wall of nose in the region of middle turbinate. May extend into adjacent paranasal sinuses.
63. 63. CT: Features are largely non-specific, demonstrating a soft tissue density mass with some enhancement. MRI often demonstrates a distinctive appearance, referred to as convoluted cerebriform pattern seen on both T2 and contrast enhanced T1 weighted images. It refers to alternate lines of low and high signal intensity.
64. 64. Fungiform papilloma These make up for half of the papillomas. They always arise from nasal septum. They are usually solitary and unilateral and may have an irregular surface. They do not have malignant potential.
65. 65. Carcinoma Squamous cell carcinoma: -This is the most common type of PNS carcinoma. -Most commonly from maxillary sinus. -6th to 8th decade. -Most of them are low grade tumors arise from nasal septum near the mucocutaneous junction. -These usually go undiagnosed untill they involve oral cavity or cheek.
66. 66. Most important feature is bone destruction even in presence of small demonstrable mass.
67. 67. Adenoid cystic carcinima These are the tumors of minor salivary glands. They most commonly affects the maxillary sinus among all the paranasal sinuses. They tend to spread along perineural sheaths and tend to leave skip lesion.
68. 68. Adenocarcinoma Arise from seromucinous glands. It is common in wood workers. Non-specific imaging features- Like bone destruction, intracranial/ intra orbital extension.. Predilection for ethmoid sinuses
69. 69. Olfactory neuroblastoma Originate from olfactory epithelium. Bimodal age distribution with one peak in young adult patients (~2nd decade) and another in 5th to 6th decades. These tumours are slow growing so bony remodelling is seen rather than bone distruction.
70. 70. The lesion is very difficult to distinguish from other malignincies except for its origin. Intracranial extension can be seen.
71. 71. Lymphoma Majority NHL. Nasal cavity and maxillary sinuses are most common sites. These tend to be grossly bulky with good enhancement. They tend to remodel the bone. Bony destruction is rare.
72. 72. Fibrous dysplasia FD is a condition in which medullary bone is replaced by a poorly organized and loosely wooven bone. There will be ground glass appearance of affected bone.
73. 73. Osteoma Mature bony outgrowth. Osteomas can be of three types: - Ivory osteoma - Mature osteoma. - Mixed.
74. 74. Kerros classification
75. 75. Kerros clssification
76. 76. FESS Its is done to regain the drainage of sinuses. Steps: -Septoplsty. -Uncinectomy. -Widening of sinus ostium and infundibulum. -Unroofing of ethmoid bulla. -Frontal sinusotomy.
77. 77. Post FESS CT scan It has to be interpreted in following ways: -Anatomical changes that have been made. -Residual or recurrent disease. -Any complications -we have to comment on Lamina papyracea, cribriform plate, roof of ethmoid and all other sinuses.
78. 78. Granulomatous diseases Wegners granulomatosis. TB Syphilis Sarcoidosis. Rhinoscleroma.
79. 79. Nasopharyngeal/ Juvenile angiofibroma Is a rare benign but locally aggressive vascular tumour. Its is highly vascular and nonencapsulated polypoidal mass that is histilogically benign but highly aggressive. Males and 2nd decade. Site: Nasopharyngeal region at pterygopalatine fossa or sphenopalatine foramen.
80. 80. Plain film: - visualisation of a nasopharyngeal mass -opacification of the sphenoid sinus -anterior bowing of the posterior wall of the maxillary antrum (Holman- miller sign). -Erosion of the medial pterygoid plate.
81. 81. CT: -Typically a lobulated soft tissue mass is demonstrated centred on the sphenopalatine foramena. -Typically bowing the posterior wall of the maxillary antrum anteriorly. - Marked contrast enhancement.
82. 82. Thank you