Hrct temporal bone pk1 ppt

this prsentation incluses HRCT temportal bone cross sectional anatomy images axial saggital and coronal with labelled diagram. This presentation help alot for radiology resident. Thanks.

1. HRCT TEMPORAL BONE Dr. Pradeep Kumar MD Radiodiagnosis

2. Radiographic positions of mastoids The mastoid process is a part of the temporal bone which is also comprised of tympanic, petrous and squamous parts. Accordingly, examination of the mastoid can be possible using the following projections: Law view : The X-ray beam is directed at a 15 degree oblique plain cephalocaudally while the skull's sagittal plane is parallel to the X-ray film. Law view: The X-ray beam is directed at a 15 degree oblique plain cephalocaudally while the skull's sagittal plane is parallel to the X-ray film.

3. Stenver's view: It is also called an Axio-anterior oblique posterior view. The X-ray beam is directed at a 14 degree angle caudally and the head faces the film with slight flexion and rotation at an angle of 45 degrees to the opposite side.

4. Transorbital view: (posterioanterior and anteroposterior): The X-ray beam is directed either postero anteriorly or anteroposteriorly along the orbito-meatal line at a 90 degree angle to the film.

5. Town's view: It is an anteroposterior view with a 30 degree fronto-occipital axial tilt. It helps in visualization of the temporal bones of, arcuate eminence, mastoid antrum, superior semicircular canal, internal auditory meatus, cochlea and external auditory meatus. It is also valuable in the diagnosis of apical petrositis and acoustic neuroma.

6. Axial anatomy from inferior to superior At the most inferior level we see the facial nerve passing inferiorly to finally reach the stylomastoid foramen (not shown in this image). The carotid artery is shown within the carotid canal. Also at this level is the top of the jugular bulb. Coronal anatomy The petrous bone is positioned in an oblique orientation from posterolateral to anteromedial. As a result most structures will be sectioned obliquely on coronal images. The following coronal images go from anterior to posterior. First we will see the tympanic membrane with the ossicles, followed by the cochlea, antrum and semicircular canals. Finally the most posterior image will show the point where the facial nerve exits the temporal bone at the stylomastoid foramen.

7. Glenoid fossa Scissura eardrum Fascial canal Mastoid air cells. Occipital condyle Jugular foramen. Foramen magnum Carotid foramen . Tensor tympani

8. Fascial canal Jugular foramen. Tensor tympani Eustachian tube Corda tympani canal

9. Fascial canal Jugular foramen. Tensor tympani

10. Tensor tympani Jugular foramen. Tympanic membrane Corda tympani canal Fascial canal

11. Tendon for Tensor tympani Jugular foramen. Osseous fascial canal External auditory canal

12. Petrous Apex. Osseous fascial canal Inferior handle of malleus Jugular f o r a m i n a. Jugular Bulb. Tendon for Tensor tympani

13. Tendon for Tensor tympani Apical turn of the cochlea Basal turn of the cochlea Handle of malleus Osseous fascial canal

14. Handle of malleus Long process of Incus Osseous fascial canal 3 rd portion Tendon for Tensor tympani Cochlear process Basal turn of cochlea Aqueduct of cochlea Promontory

15. Head of malleus Wall for middle ear Body of Incus Osseous fascial canal (3 rd portion) Tendon for Tensor tympani Cochlear process Round window Pyramidal eminence

16. Pyramidal eminence V e s tibule Osseous fascial canal (3 rd portion)

17. Ovale Window Osseous fascial canal (2 nd portion)

18. Osseous fascial canal (1 st portion) Mastoid antrum Extreme upper jugular foramen.

19. Internal acoustic meatus Aditus ad antrum Mastoid antrum

20. Lateral semicircular canal Aditus ad antrum

21. Mastoid antrum

22. Mastoid antrum Mastoid foramen Upper jugular foramen. Vestibular aqueduct

23. Mastoid foramens

24. Ma s t oid canal Superior semicircular canal. Posterior semicircular canal. jugular foramen.

25. Mastoid antrum Ear pinna Foramina for internal jugular vein Coronal section

26. internal jugular vein foramen Mastoid antrum

27. Mastoid antrum Ear pinna internal jugular vein foramen

28. Posterior semicircular canal. internal jugular vein foramen

29. Aditus ad antrum Bony canal for Corda tympanum 3 rd portion of osseous fascial canal. internal jugular vein foramen Pyramidal eminence

30. Lateral semicircular canal. 3 rd portion of osseous fascial canal. Ear pinna internal jugular vein foramen Pyramidal eminence Jugular -facial foramen

31. Lateral semicircular canal. Superior semicircular canal. Pyramidal eminence internal jugular vein foramen 3 rd portion of osseous fascial canal.

32. Lateral semicircular canal. Superior semicircular canal. internal jugular vein foramen

33. internal jugular vein foramen Superior semicircular canal. Cochlear aqueduct Round window. Septum epit y mpanum jugulare

34. epitympanum Round window. Tegmen tympani. Lateral semicircular canal.

35. Lateral semicircular canal. 2nd portion of osseous fascial canal. Ovale window. Ear drum V e s tibule Malleous Epitympanum

36. Epitympanum Tegmen tympani Incus Drum spur External auditory meatus Tympanic membrane Superior semicircular canal. Internal acoustic meatus Pro m o n t o r y

37. Epitympanum Tegmen tympani Drum spur Handle of malleous Tympanic membrane Petrous apex. 1 st portion of osseous fascial canal Basal turn of cochlea

38. Tympanic m e mbrane Drum spur Tegmen tympani malleous 1 st portion of osseous fascial canal Internal acoustic meatus

39. 1 st portion of osseous fascial canal Cochl e a 2 nd portion of osseous fascial canal Malleous Head Neck Han d le Tendon for Tensor tympani Septum epitympanum jugulare

40. Cochlea Carotid canal Coc hlear process

41. G e nicula t e ganglia. Myotendinous junction of tensor tympani Carotid canal Apex of Cochl e a Petrous apex

42. G e nicula t e ganglia. Muscle belly of tensor tympani Aditus antrum P e trous apex Carotid canal

43. Muscle belly of tensor tympani P e trous apex Carotid canal Aditus antrum

44. Head of malleous Body of incus

45. Spiral laminar bone with cochlear apex Cochlea (basal turn)

46. Pyramidal eminence Pro m o n t o r y Sinus tympani. 3rd portion of osseous fascial canal Cavernous Tympanicum

47. The internal auditory canal: Has three parts: the internal acoustic meatus (medial opening), the canal (an average of 8 mm) and the fundus, of irregular shape (modulates the passage of the VII and VIII cranial nerves). Nervous contents: the facial nerve (the largest in size) and the cochleo-vestibular nerve that divides into the cochlear nerve and the vestibular nerve which further divides itself into the superior (innervates the utricle and the ampulla of the superior and lateral SCC), and the inferior branches (innervates the saccule and the ampulla of the posterior SCC). The singular nerve (or the posterior ampullary nerve) has its proper canal, the singular canal, in the postero-inferior quadrant of the fundus that can be often be observed with 3T imaging. Vascular content: arterial by the labyrinthine artery and venous with three drainage pathways (internal auditory vein, vein of cochlear aqueduct and vein of vestibular aqueduct). The inner ear MR anatomy.

48. Axial section through the inner auditory canal (IAC) and the labyrinthe with visualization of the cochlear and inferior vestibular nerves. The utricular macula is also well depicted.

49. Anterior coronal section through the IAC. Outline of the facial nerve in its complete cisternal course, the cochlear nerve is only partially viewed.

50. Posterior coronal section through the IAC. Vestibular nerve division and vestibular ganglion (of Scarpa) are visualized.

51. Appearance variant of the vestibular nerve with inferior vestibular division into the saccular nerve (that innerves the saccule) and the posterior ampullary nerve (for the ampulla of the posterior semicircular canal). The singular canal is also frequently observed, not shown in this figure. Coronal and sagittal sections through the IAC.

52. Sagittal seriate sections of the IAC from medial (left), showing the pontocerebellar cistern, to lateral (right), showing the fundus and inner ear structures.

53. Cochlear nerve at the fundus of the IAC and its passage via the modiolus to the cochlea in an oblique sagittal section. This finding is of clinical importance when studying the inner ear malformations.

54. Heavily T2 coronal section respective to the IAC. Vestibular and cochlear structures are seen, note the utricular macula and spiral lamina.

55. Sagittal section respective to the IAC through the inner ear in a 3D Heavily T2 sequence. This section is also orthogonal to the macula of the utricle and unfolds partially the cochlea.

56. Oblique coronal section through the anterior labyrinth and fundus of the IAC, 3D Heavily T2 sequence.

57. FLAIR sequence in the axial plane four hours after Gd intravenous injection, the saccule and part of the utricle are visualized.

58. Axial FLAIR Gd sequence through the utricle, the saccule is partially visualized .

59. Heavily T2 in the plane of the lateral semicircular canal (oblique axial). The ampulla and its ampullary crest (low signal) are seen.

60. FLAIR Gd sequence section in the lateral SCC plane, passing through the utricle.

61. Section in the plane of the superior semicircular canal (plane of Pöschl, sagittal to the petrous bone), with heavily T2 sequence.

62. Section in the same plane of the superior semicircular canal with FLAIR Gd sequence.

63. T2 sequence in the plane of the posterior SCC (plane of Stenver, coronal to the petrous bone). Notice the common part of the superior and posterior semicircular canals, i.e. the common crus.

64. FLAIR and Heavily T2 sequences, sections in the coronal plane. Notice the position of the utricular macula (T2 sequence) relative to the utricle (FLAIR).

65. HRCT Temporal bone anatomy on the basis of level

66. Planes of scanning Axial 30 Degrees to anthropological base line Parallel to lateral SCC. Best displays inner & middle ear. Sections parallel to the hard Palate Direct Coronal plane patient head extended in prone or supine with 105 degree plane is perpendicular to the lateral SCC Sections are parallel to posterior wall of maxillary sinus Saggital plane 2 105 30

67. Temporal Bone 3 1.Squamous Lateral wall of MCF Petrous Encloses Labyrinth Mastoid Mastoid air cells Tympanic Forms bony EAC Styloid Forms Styloid process

68. EXTERNAL EAR MIDDLE EAR INTERNAL EAR 5 E A C Bony & membranous labyrinth

69. 6 EXTERNAL EAR Cartilaginous Lateral 1/3rd Osseous Medial 2/3rd Tympanic membrane-makes 55 degree angle With floor of the meatus

70. 7 Boundaries & Communications Of Middle Ear

71. 8 PROMOTARY- Round bulge produced by basal turn of cochlea FENESTRA OVALIS - Lies postero- superior to promontory & connects middle ear with vestibule and is occupied by footplate of stapes FENESTRA ROTUNDA- Posteroinferiorly to oval window & connects ME with scala tympani of cochlea. PROMINENCE OF FACIAL NERVE CANAL -Runs backwards just above the oval window to reach the lower margin of aditus. Medial wall of middle ear:

72. 9 ANTERIOR WALL Superior-opening of canal for tensor tympani. Middle –opening of auditory tube. Inferior-thin plate of bone separating from carotid canal. POSTERIOR WALL Aditus to mastoid Fossa incudis-lodges the short process of incus. Pyramidal eminence-attachment for stapedial tendon.

73. The scutum is normally thin and sharply edged; and is an important bony landmark as it is one of the bony structures eroded early by a cholesteatoma. • Scutum, the tympanic membrane and the tympanic annulus are best demonstrated on coronal images at the mid bony portion of the external auditory canal.

74. Cochlea The perilymphatic space of vestibule is continuous with the cochlea anteriorly. The cochlea is a conical structure,extends for 2.5- 2.75turns Promontory (P) is the projection raised by the basal turn of cochlea. The basal turn opens into the round window niche Coronal Mi d dle turn Axial

75. The vestibule consists of the superior utricle and the inferior saccule. The semicircular ducts open into the utricle.

76. The cochlear aqueduct contains the perilymphatic duct while the vestibular aqueduct contains the endolymphatic duct and the intraosseous portion of the endolymphatic sac.

77. Facial Nerve VII n:- Intracranial segment Labyrinthine segment Tympanic segment Mastoid portion Parotid segment 41

78. The facial nerve, from the lateral end of the internal auditory canal enters the petrous bone as the labyrinthine portion running anterolaterally, superior to the cochlea and towards the anterior genu (geniculate ganglion). Then it makes an abrupt turn to run posterolaterally along the medial attic wall beneath the lateral semicircular canal as the tympanic portion towards the posterior genu. And finally turns inferiorly as the descending (mastoid) portion to exit at the stylomastoid foramen.

79. How to identify Facial nerve canal? Axial: at level of Epitympanum, it is seen as a linear structure medial to ice-cream cone. ronal: At level of OW, it is seen as a round structure with bony outline between OW inferiorly and Lateral Semicircular canal (LSC)superiorly . • Coron a C l: o A

80. 46 Axial sections- caudal to cephalad 1.Axial hypotympanic-jugular foramen level carotid canal & jugular F o s s a f ormin g sn o wman Configuration opening of auditary Tube petrooccipital fissure TM joint and mandibular Condyle

81. 47 Jugular fossa Temporo mandibular jt Auditory tube Carotid canal Petro occipital fissure

82. 48 2.Axial inferior tympanic level ant &post walls of EAC descending facial nerve canal 3)carotid canal 4)cochlear aqueduct 5)long process of Malleus.

83. 49 EAC Descen d ing facial nerve Cochlear aq u edu c t P r omo n t o r y canal For tensor ty m p a ni

84. 50 3.Axial mid tympanic level neck of malleus ,long process of incus and stapes semicanal for tensor tympani 3 turns of cochlea facial nerve canal

85. 51 malleus inc u s s t apes Round window

86. 52 Oval window IAC Scala tympani Facial recess

87. 4. Axial Epitympanic IAC level Ice-cream cone appearance-head of malleus and body of incus Stapes –occasionally seen articulating with oval window. Internal auditory canal Descending facial nerve canal 53

88. 54 Ice cream cone appearance Facial nerve canal Internal auditory canal

89. 1)mastoid antrum and its aditus & Koerner’s septum 2) lateral semicircular canal and vestibule 3) post semicircular canal &vestibular aqueduct 4) IAC 5) sq part of temporal bone. 6) geniculate ganglion 55

90. 56 I A C PROXIMAL LIMB OF 7 TH N VESTIBULE LATERAL SC CANAL ADITUS TO MASTOID ANTRM VESTIBULAR AQUEDUCT

91. 57 C O R ONA L S E C TIONS 1. Coronal anterior tympanic level -Head of malleus -Tegmen tympani -Basal & 2 nd turn of Cochlea -Geniculate ganglion - scutum

92. 58 HEAD OF MALLEUS GENICULATE GANGLIA IAC COCHLEA SQ TEMP ORAL BONE SC U T U M

93. 59 2.Coronal mid-tympanic level - L shaped incudo-stapedial articulation -Stapes -Oval window -Tegmen tympani

94. 60 IAC Oval Window Incus in aditus S t a p es Tegmen tympani

95. 61 3.CORONAL - OVAL WINDOW LEVEL IAC Oval window Stapes Lateral SCC

96. 62 V es t ibule IAC Sup SCC A n trum Lateral SCC Oval window EAC Middle ear

97. 63 5.Coronal jugular foramen level Jugular foramen Descending facial Nerve Mastoid antrum Occipital bone and atlas

98. 64 Descending facial nerve Jugular fossa Mastoid Air Cells

99. Role of MRI Excellent in studying Inner ear Membranous labyrinth Vestibule Saccule & utricles Preoperative evaluation in pts for Cochlear implants To evaluate CP angle tumors To evaluate Neurovascular bundles Functional assessment – Nerve stimulation Virtual scopy 65