B SCAN
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  • 1. B – SCAN ULTRASONOGRAPHY Dr. Parameshwar Rao Dr. Haridev Dr. Ashok Dr. Siva Kumar.W (PG)
  • 2. INTRODUCTION
    • B-scan ultrasonography is an important adjuvant for the clinical assessment of various ocular and orbital diseases.
    • This presentation is designed to describe the principles, techniques, and indications for echographic examination, as well as to provide a general understanding of echographic characteristics of various ocular pathologies.
  • 3.
    • B- SCAN is a two dimensional imaging system which utilises high freq sound waves ranging from 8-10 MHz .
    • B stands for bright echoes.
  • 4. B - SCAN
    • It was first introduced by Baum and Greenwood in 1958
    • First commercially available B scan is developed by Coleman et al in seventies
    • The importance of the instrument and technique is emphasised by Karl Ossoinig
  • 5.
    • Physics:
    • It is an acoustic wave that consists of particles within the medium
    • Frequencies used in diagnostic ophthalmic ultrasound are in the range of 8-10 MHz
    • These high frequencies produce shorter wave lengths which allow good resolution of minute ocular and orbital structures
  • 6.
    • Multiple short pulses are produced with a brief interval that allows the returning echos to be detected, processed and displayed.
    • The basis of the echo system is piezoelectric element which is a quartz or ceramic crystal located near the face of the probe
  • 7. sound waves from transmitter Echoes are received by receiver Amplification Oscilloscope screen Target tissue
  • 8.  
  • 9.
    • Low frequency : orbital tissue
    • Medium frequency : ( 7 – 10 mhz )
          • Retinal , vitreous , optic nerve
          • High frequency : ( 30 – 50 mhz) :
          • ant chamber upto 5 mm
    Types of frequency
  • 10.
    • IMPEDENCE : The difference between the strength of the returning echoes from tissues with abrupt changes in acoustic properties.
    • GAIN : Increase in gain is associated with increase in tissue penetration and sensitivity but decrease in resolution.
  • 11.
    • HIGH FREQUENCIES - LOW PENETRATION BUT GOOD RESOLUTION.
    • (abdominal US-1-2MHz )
    • INCREASE IN GAIN - INCREASE IN TISSUE PENETRATION AND SENSITIVITY – DECREASE IN RESOLUTION.
  • 12. INCREASE IN GAIN - INCREASE IN TISSUE PENETRATION AND SENSITIVITY – DECREASE IN RESOLUTION.
  • 13.
    • DISPLAY MODES : A SCAN/ B SCAN / BOTH
    • TIME GAIN COMPENSATION : to enhance echoes from deeper structures.
  • 14. AMPLIFICATION
    • Three types are commonly used.
    • 1. Linear : Can show minor differences in echos . Limited range .(A SCAN)
    • 2. Logarithmic : Wider range. Minor differences cannot be seen.(B SCAN)
    • 3. S Curve : Combines the benefits of both the above.(in the standardized A SCAN for tissue differentiation)
  • 15.
    • The probe has ‘ Dampening material’ which limits the vibrations of the crystal thus shortening the pulse
    • Shape of the crystal is useful in determining the character of the sound beam
    • The electrical signal produced by returning echos is of very weak radio frequency signal
  • 16.
    • This signal undergoes complex processing before displayed on the screen
    • Adjust the amplification of the signal displayed on the screen, this is referred as ‘gain’ or ‘sensitivity’ of the instrument
    • The higher the gain level the greater the sensitivity of the instrument
  • 17.
    • It produces Two dimensional section
    • It uses both horizontal and vertical dimensions of screen to indicate configuration and location
    • A section of tissues is examined by an oscillating transducer
    Instrumentation:
  • 18.
    • An echo is represented by a dot on the screen
    • The probe is filled inside with a fluid , a crystal oscillates sending sound waves out in a fan like array called Sector scan
  • 19.
    • Image documentation modes :
    • They are of 2 types
    • stationary/static
    • moving/dynamic
  • 20.
    • The images may be saved in different
    • methods
    • Polaroid photographs
    • 35 mm photo
    • Ink prints
    • Thermal prints
    • Videotapes
  • 21.
    • Anterior segment:
    • Opaque ocular media (i.e. corneal opacities)
    • Pupillary membrane
    • Dislocation / Subluxation lens
    • Cataract / after cataract
    • Posterior capsular tear
    • Pupillary size / reaction
    • Clear ocular media
    • Diagnosis of iris and ciliary body tumors
    Indications:
  • 22.
    • Posterior segment:
    • Opaque ocular media
    • Vitreous haemorrhage
    • Vitreous exudation
    • Retinal detachment (type / extent)
    • Posterior vitreous detachment (extent)
    • Intraocular foreign body (size/ site/ type)
    • Clear ocular media
    • Tumour (size/ site/ post treatment follow up)
    • Retinal detachment (solid / exudative)
    • Optic disc anomalies
    • 3. ocular trauma
  • 23. The patient is either reclining on a chair or lying on a couch. The probe can be placed directly over the conjunctiva or the lids. Examination technique:
  • 24. Probe positions
    • Transverse : most common
    • Lateral extent, 6 clock hours
    • Longitudinal : radial ,1 clock hrs, AP diameter in Retinal tumors and tears
    • Axial : lesion in relation to lens and optic nerve .
  • 25. Transverse scan
    • EYE anaesthetised.
    • EYE – looking in the direction of observer’s interest
    • PROBE –parallel to limbus and placed on the opposite conjunctival surface
    • PROBE MARKER – superior (if examining nasal or temporal) or nasal(if examining superior and inferior).
    • 6 clock hrs examined at a time.
  • 26.
    • The clock hour which the marker faces is always at the top of the scan.
    • The area of interest in a properly done transverse scan is always at the centre of the right side of scan.
    • If examining nasal area -12 – 6 clock hrs
    • temporal - 6- 12 clock hrs
    • superior - 9 -3 clock hrs
    • inferior - 3- 9 clock hrs
  • 27. NASAL AREA TEMPORAL AREA
  • 28. SUPERIOR AREA INFERIOR AREA
  • 29.  
  • 30. Longitudinal scan
    • EYE Anaesthetised.
    • EYE - looking in the direction of observer’s interest.
    • PROBE – perpendicular to the limbus and placed on the opposite conjunctival surface.
    • PROBE MARKER- directed towards the limbus or towards the area of interest regardless of the clock hour to be examined.
    • Optic nerve shadow always at the bottom on the right side.
    • 1 clock hour .
  • 31. Axial scan
    • EYE anaesthetised.
    • EYE – in primary gaze
    • PROBE – centered on the cornea .
  • 32.
    • LENS : Oval highly reflective structure with intralesional echoes with none to highly reflective echoes.
    • VITREOUS is echolucent.
    • RETINA, CHOROID AND SCLERA : Are seen as a single reflective high structure.
  • 33.
    • OPTIC NERVE : Wedge shaped acoustic void in the retrobulbar region.
    • EXTRA OCULAR MUSCLES : Echolucent to low reflective fusiform structures. The SR- LPS complex is the thickest. IR is the thinnest. IO is generally not seen except in pathological conditions.
  • 34.
    • ORBIT -highly reflective due to orbital fat.
    • Always examine the other eye before coming to a conclusion regarding the lesion .
    • Opacities produce dots or short lines
    • Membranous lesions produce an echogenic line
  • 35. Anterior segment evaluaton
    • Immersion technique
    • High resolution technique
  • 36. ULTRASONOGRAPHIC CHARACTERISTICS
  • 37. VITREOUS HAEMORRHAGE To detect extent, density, location and cause Fresh haemorrhage shows dots or lines Old haemorrhage the dots gets brighter
  • 38. POSTERIOR VITREOUS DETACHMENT Posterior vitreous detachment: The detached posterior vitreous is seen as membranous lesion with no/some attachments to the optic disc
  • 39. POSTERIOR VITREOUS DETACHMENT Mobility of PVD is more than RD. The spike of RD is more than PVD. PVD becomes more prominent in higher gain settings
  • 40. RETINAL DETACHMENT The detachment produces a bright continuous, folded appearance with insertion into the disc and ora serrata. It is to determine the configuration of the detachment as shallow, flat or bullous
  • 41. EXUDATIVE RETINAL DETACHMENT
  • 42. RHEGMATOGENOUS RD
  • 43.
    • RHEGMATOGENOUS RETINAL DETACHMENT
  • 44. CLOSED FUNNEL RD WITH RETINAL CYST
  • 45. CLOSED FUNNEL RD WITH RETINAL CYST
  • 46. APPEARS AS RD BUT IT IS A PVD. CLUES : NON UNIFORM THICNESS OF MEMBRANE VERY THIN ATTACHMENT TO THE DISC.
  • 47. RETINAL TEAR
  • 48. RETINAL TEAR WITH FREE SUPERIOR END . THE MEMBRANE IS CONVOLUTED ON ITSELF. POSTERIOR VITREOUS IS ATTACHED AT THE SUPERIOR END OF THE TEAR.
  • 49. ASTEROID HYALOSIS Asteroid hyalosis: Calcium soaps produce bright point like echos
  • 50.
    • Differentiation, extrascleral extension, size, assessing tumour growth or regression.
    • Measurement of tumour dimensions such as elevation and base.
    • Help in distinguishing solid from cystic lesions.
    TUMOURS
  • 51. RETINOBLASTOMA Size of the tumour Shows irregular configuration Calcification shows high internal reflectivity
  • 52.  
  • 53.  
  • 54. Collar button or mushroom shape.Large tumours shows acoustic hallowing MELANOMA
  • 55. TUMOURS - OSTEOMA
  • 56. CHOROIDAL DETACHMENT KISSING CHOROIDS Smooth, thick, dome shaped membrane in the periphery with very little after movement 360 degree detachment shows a pathognomonic “scalloped appearance
  • 57. CHOROIDAL DETACHMENT KISSING CHOROIDS
  • 58. CHOROIDAL DETACHMENT
  • 59.
    • Intraocular foreign bodies:
    • Localisation and extent of intraocular damage
    • Metallic foreign bodies produce very high bright signal
    • Shadow present posterior to the foreign body
    • Wood, glass and organic material produce specific echographic finding
  • 60. INTRA OCULAR FOREIGN BODY
  • 61. CUPPED DISC
  • 62. MACULAR EDEMA
  • 63. PERSISTENT HYALOIDAL VESSEL
  • 64. POSTERIOR STAPHYLOMA
  • 65. LACRIMAL GLAND TUMOUR
  • 66. NANOPHTHALMOS
  • 67. RETINOSCHSIS
  • 68.
    • Retinoschisis:
    • Smooth, thin dome shaped membrane that doesn’t insert on optic disc
    • Diabetic retinopathy:
    • Nature and extent of the disease
    • To monitor progress of the disease
    • Aids in pre – vitrectomy evaluation
  • 69. ENDOPHTHLMITIS
  • 70. CYSTICERCOSIS WITH RETINAL TEAR
  • 71. COLOBOMA OF THE CHOROID AND DISC
  • 72. PERSISTENT FETAL VASCULATURE
  • 73. RETINOPATHY OF PREMATUIRITY
  • 74. POSTERIORLY DISLOCATED LENS
  • 75. INTRA OCULAR AIR / GAS
  • 76. SILICON OIL FILLED VITREOUS
  • 77.
    • Sclera:
    • Thickening in hyperopic and nanopthalmic eyes
    • Infolding in severe hypotony or a ruptured globe
  • 78. SCLERITIS
  • 79.
    • Normal muscles show less echo dense than surrounding orbital soft tissue
    • Documenting the gross size and contour of a muscle
    Evaluation of extraocular muscles:
  • 80. Nodular posterior scleritis with fluid in the Tenon capsule. Positive T-sign at the insertion of the optic nerve.
  • 81. Evaluation of optic nerve
    • General topography, relationship to structures, optic disc anomalies and alteration in contour of the globe
    • The subarachnoid space surrounding optic nerve appears as echolucent cresentric or circle around the nerve called ‘ Doughnut sign’
  • 82.
    • Non invasive
    • Performed in an office setting
    • Does not expose to radiation
    • High resolution echography provides reliable and accurate assessment
    • Ideal for follow up of lesion
    Advantages:
  • 83. Disadvantages
    • High frequency sounds waves have limited penetration
  • 84.
    • Useful in the following conditions:
    • Abnormal size of eye
    • Abnormal shape of eye
    • Congenital abnormalities
    • Vitreous alterations
    • Retinal detachments (type/ location)
    • Ocular and orbital tumours
    • Trauma
    ULTRASONOGRAPHY IN PAEDIATRIC PATIENTS:
  • 85.
    • Artefacts :
    • Insufficient fluid coupling ( i.e., lack of methyl cellulose) cause entrapment of air between the probe and eye leading to display of bright echos which represent multiple signals
    PITFALLS
  • 86. REVERBERATION ARTEFACTS
  • 87. ANGLE OF INCIDENCE ARTEFACT
  • 88. PITFALLS
    • Tumours :
    • Mass may be missed is less than 0.75 mm
    • False –ve results in case of small lesion and fibrotic tissue
    • False + ve in subretinal haemorrhage and metastatic tumour with massive infiltration
  • 89.
    • Vitroretinal disease:
    • In RD unable to detect actual tear
    • In vitrectomsed eyes vitreous haemorrhage is diffuse leading to echolucency
    • Silicon oil decrease in sound velocity
    PITFALLS
  • 90. PITFALLS
    • Intraocular foreign body :
    • Small Intraocular foreign body of < 1mm
    • may be missed.
    • Orbit:
    • An orbital mass can be detected or
    • differentiated if > 3 mm in size if anterior and
    • > 5 mm in posterior orbits.
  • 91. B- SCAN REPORTING
    • Describe the features and correlate with clinical findings.
    • Dont jump to diagnosis.
    • Always examine both in sitting and erect postures in case of RD.
    • Examine other eye also.
    • Try to take the best picture possible.
  • 92.
    • FOUR TRANSVERSE SCANS
    • ONE HORIZONTAL AXIAL SCAN TO EVALUATE THE POSTERIOR POLE ARE SUFFICIENT.
  • 93. THANK YOU