B SCAN

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B SCAN

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

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