B SCAN BY DR.PUSHKAR DHIR, DHIR HOSPITAL BHIWANI.pptx

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1. Dr.Pushkar Dhir DHIR EYE HOSPITAL & POST GRADUATE INSTITUTE OF OPHTHALMOLOGY BHIWANI HARYANA

2. B SCAN Moderator :- Dr. Supreet Juneja Presentor :- Dr.Pushkar Dhir

3. D 4 CONCEPTS How B scan came into existence? Concept of Frequency. Concept of Gain.

4. ULTRASONOGRAPHY Non-invasive, efficient and inexpensive diagnostic tool. Examiner- dependent Expertise A correlation with clinical findings is essential to make a diagnosis. .

5. 1793: Lazzaro Spallanzani (Italy) discovered that bats orient themselves with the help of sound whistles while flying in darkness. This was the basis of modern ultrasound application

6. 1956: Mundt and Hughes - first used the A-scan technique . 1958: Baum and Greenwood - B-scan (immersion method) 1962:Oksala and Lehtinen further refined the technique In the sixties, imaging of the eyeball and orbit using ultrasound was popularised by Ossoining .

7.  Apna B Scan 

8. INSTRUMENTATION An USG unit is composed of four basic elements : Pulser , Receiver Display screen Transducer

9. B SCAN CONTROL PANEL

10. USE OF INCREASING GAIN

11. Use of Decreasing Gain

12. PRINCIPLE OF ULTRASOUND VELOCITY REFLECTIVITY ANGLE OF INCIDENCE ABSORPTION USG wave has a frequency > 20 kHz. Wavelength α Depth of penetration of the ultrasound. Larger d frequency = short wavelength = shallow penetration = better resolution Sound travels faster through solids than liquids. Velocity of sound wave is depends on the density of the media . Vitreous 1532 m/s Cornea speed of 1,641 m/s Greater the density difference at interface, stronger the echo/higher the reflectivity The stronger the echo, the higher the spike The stronger the echo, the brighter the dot. Perpendicular d probe to the area of interest, =more of the echo is reflected directly back into the probe tip. = brighter d spot. More dense the medium, the greater the amount of absorption. B-scan should be performed on the open eye unless the patient is a small child or has an open wound

13. PTR before doing Bscan For Best B scan results :- Put the Probe directly on globe ( improve resolution and determine the patient gaze) Coupling jelly applied to probe tip In cases of suspected infection cover the probe tip with cling film Clean the probe tip with alcohol wipe after every use.

14. REQUISITE 4 HIGH QUALITY BSCAN Lesion Must be Placed in the centre Beam must be directed perpendicular to the surface of interest Lowest Possible decibel gain that is consistent with adequate mantainence of intensity and resolution of lesion.

15. ABOUT THE PROBE 1-5 MHZ = Abdominal USG 8-10 MHZ = Ophthalmic USG 50-100 MHZ = UBM

16. B Scan : Orientation & Labeling Axial Section Transverse Section Longitudinal Section

17. Normal B-scan Cornea, AC and the anterior capsule- not easily visualised without immersion technique Lens –oval high reflective structure Vitreous - acoustically clear Retina, choroid and sclera- seen together as a high reflective structure Sclera – 100% reflective Optic nerve- wedge shaped acoustic void in retrobulbar space on axial scan Extraocular muscles- echolucent to low reflective fusiform orbital structures

18. Bscan in Various Pathologies

19. PVD RETINA DETACHMENT CHOROID DETACHMENT SHAPE Linear LOCATION ATTCH. TO ON Variable Yes No OTHER Thicker inferiorly Folds/Breaks Vortex Vein SPIKE HT. 40-90% 80-100% 90-100% SPIKE PEAKS Single Single Double / M shape peak MOBILITY Marked (Hammock like) Moderate Minimal AFTER MOVMT. Marked Moderate to severe Absent

20. References Most of the photographs and pics hav been taken from Textbook of Ophthalmic Ultrasound by Hatem R. Aata WITHOUT PRIOR PERMISSION.

21. Correlation with clinical findings is essential to make a diagnosis 

22. THANK YOU EVERYONE FOR PATIENTLY LISTENING TO THIS SEMINAR. For feedbacks & brickbats plz mail at [email protected]./[email protected] “ Thank you for listening B scan”

23. Vitreous syneresis Clumps of cells compromised of blood Uveitis Endophtalmitis Asteroid Hyalosis