Skull radiography

Skull radiography - views with radiological approach for skull radiograph

1. SKULL RADIOGRAPHY CHAIRMAN – DR VIRUPAXI HATTIHOLI CO CHAIRMAN – DR A C SHETTI PRESENTER – DR SUDHIR PATEL

2. Introduction In the past skull radiographs were considered an essential step in the investigative protocol of a patient suspected to have neurological disease. Now , With the availability of CT and MRI there has been a dramatic decline in the use of plain films and the indications for skull radiographs have been redefined. The major indication for skull radiographs is in the evaluation of skeletal dysplasias , diagnostic survey in abuse, abnormal head shapes, infections and tumors affecting the skull bones, metabolic bone disease, leukemias and multiple myeloma. Abnormalities in skull radiographs my be seen in the form of change in the density, size and shape of the skull, as well as skull defects.

3. -form protective housing of brain (cranial vault) 14 Facial 2 types of Skull bones 8 Cranial -provides structure, shape & support for face protective housing for upper ends of respiratory & digestive tracts with cranial-forms eye sockets

4. The 8 Cranial Bones are: 1 Frontal 2 Parietal 1 Occipital 1 Ethmoid 1 Sphenoid 2 Temporal

5. Top of skull = skull cap = Calvarium It is made up of 4 bones Frontal L & R Parietal Occipital

6. 2 parietal bones

7. The Floor of the Cranium is made of 4 bones (The four on the floor!) The Ethmoid The Sphenoid Left & Right Temporal bones

8. 1 Ethmoid Bone & 2 Temporal bones

9. Temporal Bones AP

10. 1 Sphenoid bone

11. ANATOMICAL VIEW OF BASE OF SKULL FROW ABOVE

12. Few terms in base of skull Basilar invagination Superior migration of vertebral elements mostly dens due to softening of bones of base of skull like Paget’s disease, hyperparathroidism , RA, osteogenesis imperfecta , rickets , hurler’s syndrome , osteomalacia , FD etc… Basilar impression Superior migration of vertebral elements mostly dens into normal foramen magnaum . congenital anomaly like atlanto -occipital fusion , klippel feil syndrome, chairi malformations, down syndrome etc.

13. McGregor’s line line is drawn from the posterosuperior margin of the hard palate to the most inferior surface of the occipital bone. the odontoid apex should not lie above this line > 8 mm in males and > 10 mm in females.

14. Basilar Angle & Platybasia Three points are located and joined together by two lines; the subsequent angle is measured. The three points are the nasion , the center of sella turcica & and the basion . normal range - 123-152°. index of the relationship between the anterior skull and its base. The angle will increase beyond 152° in platybasia , in which the base is elevated in relation to the rest of the skull. This may or may not be associated with basilar impression. The deformity may be congenital (isolated impression, occipitalization ) or acquired (Paget’s disease, rheumatoid arthritis, fibrous dysplasia).

15. There are 14 Facial Bones 2 maxillary bones 2 nasal 2 lacrimal 2 Zygoma (malar) 2 palatine 2 inferior nasal conchae 1 vomer 1 mandible

16. 2 Maxillary bones

17. 2 nasal bones 2 lacrimal bones

18. 2 Zygomas

19. 2 Palatine bones

20. 2 inferior nasal conchae

21. 1 Vomer

22. 1 Mandible

23. PNS WATERS VIEW FOR ALL FACIAL BONES

24. What are fontanels & sutures ? Six areas of incomplete ossification in a newborn

25. Fontanels Soft spots Present at birth Areas of Unossified connective tissue Where three or more bones are joint Six Fontanels Gradually replaced with bone Allow for skull compression during birth Most prominent are the anterior and posterior fontanels Located on the anterior and posterior ends of the sagittal suture

26. Fontanels Articulation between the frontal and both parietal bones at the anterior end of the sagittal suture is the bregma Articulation between the occipital bone and both parietal bones at the posterior end is the lambda Anterolateral (sphenoid) fontanel is the pterion Posterolateral fontanel is the asterion

27. Mastoid fontanel (asterion) Sphenoidal fontanel (pterion)

28. At what age do the fontanels close? Posterior and sphenoidal fontanels close during first 1-3 months after birth Anterior and mastoid fontanels close during 2 nd year of life

29. Sutures Normal suture develop late at 16 weeks of gestation Sequence of closure --- Metopic coronal lambdoid Saggittal Distance more than 2 mm after age of 3 yrs is stated as sutural diathesis

30. All skull positions are based on 3 factors Rotation Tilt Flexion-Extension

31. 3 types of Skull Position change 1st type - Rotation - head is rotating on an axis-your neck The “NO” position

32. 2 nd type of skull position change Flexion-extension Also called “Yes” position

33. 3 rd type of skull position change Tilt Or “Maybe” position

34. Major Lines used in Skull Radiography Inter-orbital / Inter- pupillary line Infraorbital line Anthropological baseline - from Infraorbital point to upper border of EAM Orbito-Meatal / Radiographic baseline - From outer canthus of eye to centre of EAM Auricular vertical line - Passes through vertex & centre point of EAM

35. SAME LINES SHOWN ON A LATERAL XRAY FILM

36. Planes

37. General guidelines Skull radiography Remove all metal objects, unite bunches of hair to reduce artefacts Protection: Full coat apron with lead to back or half apron draped over back of chair. Forty-five-degree triangular pads are extremely useful for immobilizing children. They can be held by the parent and support the head. Straps are used to immobilizing adult a patient on a skull unit. Individual side markers. Use 70–85 kV tube voltage Fixed focus 100 cms . 24 x 30-cm cassettes are generally used for plain skull radiography.

38. Occipito -frontal projections Central ray is parallel to the sagittal plane are named according to the direction of the central ray. Central ray enters the skull through occipital bone and exits through the frontal bone... Therefore called occipto -frontal (OF) projection. centering at nasion .

39. collimation field should include the vertex of the skull superiorly, the region immediately below the base of the occipital bone inferiorly & lateral skin margins. Ensure No Rotation – assessed by measuring the distance from a point in the midline of the skull to the lateral margin. Occipito -frontal caudal angulation : 10 , 15 & 20 degrees. Degree of beam angulation evaluated by assesement of petrous ridges within the orbit.

40. OF / PA VIEW Nasal Septum Frontal Sinus Maxillary Sinus Ethmoid Sinus Inferior Turbinate Superior orbital fissure Sagittal suture Coronal suture Sphenoid ridge Mastoid process Hard palate Innominate line Petrous ridge 2 1 4 3 5 6 7 8 9 10 12 11 13

41. 46 Caldwell Sinus Projection / Occipito -frontal 15 degree caudad view The Caldwell Projection will have the petrous ridges below the orbits. This view will provide a clear view of the frontal and ethmoid sinuses. The super orbital rims can be evaluated for fracture when facial bone are of interest.

42. SINUS CALDWELL VIEW FRONTAL SINUS SPHENOID BONE MAXILLARY SINUS INFERIOR TURBINATE MANDIBLE HARD PALATE MASTOID AIR CELLS ORBIT ETHMOID

43. SINUSES 1. Frontal sinus 2. Ethmoid Sinus 3. Nasal Septum (bony) 4. Zygomatical -Frontal Suture 5. Maxillary Sinus 6. Zygoma 7. Zygomatic Arch 8. Mandible 9. Inferior orbital margin 10. Left orbit 8 1 2 5 7 9 10 3 4 AP WATERS VIEW 6

44. Fronto -occipital projections Central ray is parallel to the sagittal plane, except that the central ray now enters the skull through the frontal bone and exits through the occipital bone. Used for immobile patients , same anatomy demonstrated as OF projections...but orbits & frontal bones are magnified . Centring is done at external occipital protuberance.

45. Beam angulation Many OF and FO projections will require central ray to pass along the sagittal plane at some angle to orbital- meatal plane. In these cases, the degree of angulation is stated after the name of the projection, than direction of angulation mentioned. Caudo -cranial angulation involves the beam pointing up body towards the head (written in short form as ↑). Cranio -caudal angulation involves the beam pointing down body towards feet (written in short form as ↓). Example - fronto -occipital 30-degree cranio -caudal projection (FO30° ↓).

46. Chamberlain-Townes / Fronto -occipital 30 degree caudad projection The tube is angled 30 degree to orbito-meatal line caudally to throw the anterior part of the skull away from the occipital region of the skull. 51

47. SKULL Townes view 1 . Parietal bone 2. Lambdoid suture 3. Foramen magnum 4. Petrous temporal bone 5. Mandible Mastoid air cells Transverse sinus Sphenoid sinus Greater wing of sphenoid Superior sagttal sinus 4 5 1 1 2 3 6 7 8 9 10

48. Lateral projection Central ray passes along a coronal plane at right-angles to the median sagittal plane. Named according to the side of the head nearer to the image receptor. In example, the beam enters the head on the left side, passes along a coronal plane, and exits the head on the right side, where the image receptor is located. therefore, a right lateral projection.

49. Centre midway between the glabella and the external occipital protuberance to a point approximately 5 cm superior to the external auditory meatus . Collimation: slightly less than film size

50. Lateral with angulation Central ray passes along a coronal plane at some angle to the median sagittal plane, then the degree of angulation is stated. Example of right lateral with 30-degree caudal angulation (R Lat 30°↓).

51. Oblique projections Oblique projection is obtained when the central ray is at some angle to the median sagittal plane and the coronal plane. How the projection is named will depend on two factors: 1 ST whether the anterior or posterior portion of the head is in contact with the cassette 2 ND whether the left or right side of the head is in contact with the cassette . Example of 40 degree left anterior oblique

52. Fifty-five-degree left anterior oblique with 35 degree caudal angulation / optic foramina view The head has been rotated, such that the right side of the face is in contact with the cassette and the median sagittal plane makes an angle of 55 degrees to the Bucky. the central ray has a 35-degree caudal angulation .

53. XRAY VIEW OF OPTIC FORAMINA

54. SUBMENTOVERTICAL VIEW Routine skull view that can be used to evaluate the upper cervical spine. Provides an axial view of C-1 and C-2 as well as the foramen magnum. 60

55. Erect The patient sits a short distance away from a vertical Bucky. The neck is hyperextended to allow the head to fall back until the vertex of the skull makes contact with the centre of the vertical Bucky. The head is adjusted to bring the external auditory meatuses equidistant from the cassette. The median sagittal plane should be at right-angles to cassette along its midline. The orbito-meatal plane should be as near as possible parallel to the cassette .

56. The central ray is directed at right-angles to the orbito-meatal plane and centred midway between the external auditory meatuses . Collimation: slightly less than film size or skin of skull Breathing Instructions: suspended respiration Make exposure Erosion of the bony margins of the skull-base foramina is an important indicator of destruction by tumour. 62

57. 3 2 4 6 1. Lat. & Med. ptyergoid plate 2. Ethmoid Sinus 3. Odontoid Process 4. Sphenoid Sinus 5. Foramen ovale 6. Maxillary Sinus 7. Mastoid air cells 8. Ant arch of C-1 9. Margin of foramen magnum 10. Ext. auditory canal 11. Foramen spinosum 12. Carotid canal 13. Cervical spine 7 9 1 5 8 10 BASE OF SKULL 11 12 13

58. Radiological Approach For Skull X-rays Abnormalities that can be detected on the plain skull X-rays can be categorized in the following groups: Abnormal density (increased or decreased) Abnormal contour of the skull Abnormal intracranial volume Increased thickness of the skull Single lucent defect / Multiple lucent defects Sclerotic areas Intracranial calcification

59. Abnormal Density GENERALIZED REDUCED DENSITY Thinning of the skull bones with decreased done density is seen in osteogenesis imperfecta , hypophosphatasia & achondrogenesis . In hypophosphatasia ( reduced serum alkaline phosphatase )- decreased ossification of the skull and vertebrae or as isolated areas of unusually thin calvarial bone. FOCAL REDUCED DENSITY: Focal areas of defective ossification can occur in the lacunar skull where in well-defined lucent areas are seen corresponding to nonossified fibrous bone and the lacunae are bounded by normally ossified bone.

60. OSTEOGENESIS IMPERFECTA (BRITTLE BONE SYNDROME ) increased osseous fragility leading to multiple fractures with Osteopenia Blue sclerae intrasutural ( wormian ) bones Dentinogenesis imperfecta Platybasia

61. Craniolacunia : Lateral skull radiograph in an infant shows multiple lucencies with intervening dense areas typical of craniolacunia . With associated occipital encephalocele and absence of sutural widening

62. GENERALIZED INCREASED DENSITY Sclerosing bone dysplasias such as osteopetrosis & Pyknodysostosis . LOCALIZED INCREASED DENSITY fibrous dysplasia, osteoma , craniometaphyseal dysplasia , etc.

63. Osteopetrosis (marble bone disease): Due to defective osteoclastic resorption of primary spongiosa of bone Frontal radiograph shows diffuse increased density affecting all bones of the skull vault as well as base Poorly developed PNS & Mastoid air cells.

64. PYKNODYSOSTOSIS Wormian bones delayed closure of the fontanelles generalized increase in density of the skeleton (particularly the calvarium , skull base and orbital rims) hypoplastic facial bones straight mandible

65. Fibrous dysplasia. Developmental disorder of the bone (which ceases growth with maturity) Medullary bone is replaced with well-defined areas of fibrous tissue later then ossify. Patchy sclerosis affecting the vault and the base of the skull. CT demonstrating expanded and abnormally mineralized bone occupying the skull base.

66. Osteoma . commonly affect the paranasal sinuses (frontal and ethmoid > sphenoid sinus Multiple osteomas occur in Gardner’s syndrome A homogeneous smooth dense lesion with a well-defined spherical margin ▶ it is attached to underlying bone ▶ it rarely exceeds 2–3cm diameter

67. Abnormal Contour of the Skull Normal contour of the skull is maintained by sutures, the intracranial contents and normal bone formation...Abnormality in any of these result in abnormal contour of the skull. PREMATURE FUSION OF THE SUTURES Normal suture develop late at 16 weeks of gestation Sequence of closure --- Metopic – coronal – lambdoid – saggittal craniosynostosis -commonest cause ... Suture is obliiterated by diffuse or focal bony beaking .... Location Sagittal (60%, most common single suture) Coronal (22%) , Metopic (15%), Lambdoid (2%) & Multiple (5%)

68. Primary simple non- syndromic type : this usually involves one suture Complex syndromic type : this involves many sutures Secondary craniosynostosis : this is due to disrupted growth caused by drugs, metabolic bone disease, or an underlying small brain ( microcephaly ) Skull growth decreases perpendicular to the suture and increases parallel to it (therefore a normal skull shape makes craniosynostosis unlikely) Clinical features An abnormal skull shape ▶ visual failure ▶hydrocephalus

69. Scaphocephaly Most common type - Sagittal suture synostosis Elongated “ dolichocephalic ” / boat shaped skull with midline bony ridge

70. Trigonocephaly Metopic suture synostosis Wedge- or triangle-shaped forehead with vertical ridge of bone & widened transverse diameter of calvaria

71. Brachycephaly Bicoronal or bilambdoid synostosis Coronal → foreshortening in AP & widened transverse dimension ± “harlequin” orbit ( lateral elevation of sphenoid wing ) , hypertelorism Lambdoid → flattened occiput

72. “Cloverleaf” Skull Bicoronal + bilambdoid synostoses Temporal fossae bulge outward, “towering” skull, shallow orbit Signs of raised ICP in the form of increased convolutional markings.

73. Plagiocephaly Usually multiple sutures or unilateral coronal Skull very asymmetric Oxycephaly The coronal , sagittal & lambdoid stutures are all fused.

74. Arachnoid cyst: Basal view of skull shows thinning and ballooning of anterior and lateral walls of the left middle cranial fossa Expansion of the bony calvarium due to the presence of slow growing intracerebral or subarachnoid space occupying lesions such as arachnoid cysts may also result in abnormal contour. The bony vault bulges outwards with thinning of the inner table. Chronic subdural hematomas may also cause expansion of the adjacent calvarium and may even erode the inner table. Calcifications when present facilitates the diagnosis.

75. Abnormal bone formation Achondroplasia characterized by defective endochondral bone formation Shortening of the bones of the skull base as these bones develop from cartilage... Since the bones of the vault develop from membranous bones, these remain unaffected. Short skull base with Enlarged cranial vault with frontal bossing and large jaws. Narrow cervical canal

76. Abnormal Intracranial Volume Size of the calvarium is dependent on the size of the intracranial contents. Assessing the size of the skull - compare the skull vault to the size of the face. At birth, the volume of skull is approximately four times that of face. This ratio decreases to 3:1 by age 2 and 1.5:1 by adulthood. ENLARGED HEAD SIZE Hydrocephalus - congenital obstruction of the ventricular system with Raised ICP . Sutures become wide due to expansion of the intracranial contents. Macrocephaly , Pituitary dwarfism.

77. SMALL HEAD SIZE Microcephaly – associated with mental retardation Otherwise normal contour Cranial sutures fuse early Sinuses are large Convolutional markings are absent or decreased Differention of premature closure of all the sutures from microcephaly with fused sutures When multiple sutures fuse prematurely, the fusion does not occur simultaneously so irregular skull due to expansion of the skull in unusual directions to accommodate the brain. Clinically signs of raised intracranial tension are present. Convolutional markings are exaggerated.

78. Increased thickness of the skull may result due to early cessation of brain growth or cerebral atrophy . Increased width of diploic space due to increased hematopoiesis is seen in hemolytic anemias - hyperplasia of the bone marrow Examples - Thalassemia ,sickle cell disease, hereditary spherocytosis The diploic space is widened with striking radial striations, the “hair-on-end” appearance The paranasal sinuses may also be completely obliterated due to widening of the diploic space of facial bones. Progressive hydrocephalus leads to large bony calvarium and a decreased diploic space

79. THALASSEMIA Lateral skull radiograph shows widened diploic space with coarsened trabeculae giving “Hair-on-end” appearance Sinuses obliterated typical of hemolytic anemia

80. Single Radiolucent Defect Evaluate for location, associated soft tissue swelling, table of the bone involved and margins of the lytic lesion, whether well-defined , ill-defined or sclerotic. Variety of causes – congenital or acquired . Congenital causes parietal foramina, anomalous apertures, meningoencephalocele or dermal sinus Acquired causes Trauma, infections, tumors and histiocytosis . Bilaterally symmetrical rounded lytic defects located in posterior parietal bone are characteristic of parietal foramina and are of no clinical significance. Lytic defects due to meningoencephalocele are located in the midline in the frontal or occipital regions and have sharp margins . Associated soft tissue mass helps the diagnosis. In the first 3 months of life, meningoencephalocele is generally associated with lacunar skull ( craniolacunia )

81. Craniolacunia : Lateral skull radiograph in an infant shows multiple lucencies with intervening dense areas typical of craniolacunia . With associated occipital encephalocele

82. FRACTURES occur at the site of injury , associated with soft tissue swelling. Linear nondepressed fractures seen as radiolucent lines and should not be confused with sutures or vascular grooves. Fracture lines are nontapering , nonbranching and have sharp borders whereas vascular grooves have ill-defined borders and an undulating course. Sutures are seen in known anatomical positions and have saw tooth edges. Depressed fractures Generally occur after severe trauma . Radiologically the depressed fragment presents as area of increased radiodensity surrounded by a radiolucent zone .

83. Depressed fracture : Frontal radiograph shows the parallel dense lines due to depressed bone fragments and associated lucency due to absence of bone.

84. Growing fracture In children, when the dura beneath the suture is torn, the arachnoid membrane herniates through the dura into the bony defect. The pulsations of the brain lead to progressive enlargement of the arachnoid collection resulting in expansion of the fracture line termed as growing skull fracture. The bulging membranes result in the formation of leptomeningeal cyst.

85. Dermoid / Epidermoid tumors of scalp Congenital inclusion of epithelial cells within the calvarium Skull radiograph shows a well circumscribed lytic lesion with sclerotic margins overlying the coronal suture Dermoid always located midline Intracranial epidermoid produce same appearance –CT scan – to differentiate location.

86. INTRACRANIAL EPIDERMOID TUMOR (A) Skull radiograph shows a well circumscribed lucency overlying the coronal suture mimicking a lytic lesion. (B) Coronal CT scan in the same patient shows a large hypodense lesion due to epidermoid in the temporoparietal region. No lytic lesion of skull vault is seen.

87. HISTOCYTOSIS Complex Of Eosinophilic Granuloma, Hand- Schüller -Christian disease & Letterer- Siwe disease. Eosinophilic granuloma -Lateral skull radiograph shows a single small lytic lesion having sharp nonsclerotic border and bevelled edges Occasionaly small bone present in centre – button Sequestrum

88. Histiocytosis (Hand- Schüller -Christian disease): Lateral radiograph of skull shows multiple well-defined lytic lesions of the vault with bevelled edges characteristic of histiocytosis

89. Osteosarcoma : (A) Large lytic area with irregular margin is seen affecting the left parietal bone. (B) CT scan of the same patient shows the soft tissue swelling, destruction of the bone and extradural extension of the tumor

90. MULTIPLE RADIOLUCENT DEFECTS In children Craniolacunia Multiple Wormian bones- along suture line, due to defective mineralisation... osteogenesis imperfecta , hypothyroidism , pyknodysostosis etc. Increased Convolutional makings due to raised intracranial tension Histiocytosis Metastasis from neuroblastoma , leukemia or Ewing’s sarcoma. In adults multiple myeloma, metastasis and hyperparathyroidism

91. Hyperparathyroidism “Pepper pot” skull / “salt & pepper” skull Lateral skull radiograph shows multiple lytic lesions with mottled appearance Loss of inner & outer tables definition

92. Multiple myeloma: Lateral skull radiographs shows multiple well-defined punched out lytic lesions with osteroporosis affecting the skull vault as well as mandible typical of myeloma Differentiation from metastasis is difficult

93. Increased Density /Sclerotic Areas of the Skull Normal as well as pathological conditions. Osteopetrosis Fibrous dysplasia Paget disease Osteoma Thickening of the frontal and parietal bones may occur in rickets Meningioma Hyperostosis frontalis interna

94. Paget’s disease Initial lytic (hot) phase: increased osteoclastic activity results in bone resorption (with osteoblastic activity lagging behind)- osteoporosis circumscripta Intermediate (mixed) phase: increased bone resorption is followed by increased formation of abnormally coarsened trabeculae ▶ corticomedullary differentiation is lost Late sclerotic (cold) phase: osteoblastic activity predominates, generating disorganized bone of increased density Skull shows focal areas of opacities in previous areas of osteoporosis giving “cotton wool” appearance

95. Sphenoid wing meningioma : (A) PA view of skull shows hyperostosis of the left lesser and greater wings of the sphenoid bone typical of meningioma . (B) Contrast enhanced CT scan in the same patient shows proptosis and hyperostosis of sphenoid wings with enhancing extradural mass due to meningioma on the left side

96. Hyperostosis frontalis interna Lateral skull radiograph shows irregular thickening of the frontal bone in an elderly female. The inner table is involved more than the outer table with sparing of diploic spaces

97. Intracranial Calcification Physiological Calcification Pineal gland typical in midline approx. 3 cms above & behind to posterior clinoids in lateral view ... If Size increase suspect pinealoma . Habenular commissure calcification Choroid plexus calcification Falx Familial conditions • Tuberous sclerosis • Sturge -Weber syndrome • Idiopathic familial cerebrovascular calcinosis ( Fahr’s disease) Metabolic causes • Hypoparathyroidism & Pseudohypoparathyroidism

98. Inflammatory disease • CMV Infection , Toxoplasmosis , Rubella • Abscess Vascular causes • Arteriovenous malformation • Intracerebral hematoma • Subdural hematoma Neoplasms • Suprasellar Craniopharyngioma • Astrocytomas & Oligodendrogliomas • Pinealoma & meningioma

99. Vastine -Kinney Method of Pineal Gland Localization Anteroposterior (AP) position. Measurement A is plotted against the sum of A and B and should fall within the specified range. Superoinferior position. Measurement C is plotted against the sum of C and D and also should fall within a specified range. A pineal shift may be caused by a space-occupying mass, such as a tumor , hemorrhage , or localized atrophic cerebral disease..

100. Sturge -Weber syndrome: PA and lateral view of the skull shows gyriform calcification on the left side.

101. Thank you . Next teaching programme – Case Presentation – Siddharth k