B SCAN

Moderator :- Dr. Supreet Juneja Presentor:- Dr.Pushkar Dhir

D 4 CONCEPTS

1. How Bscan came into existence?

2. Concept of Frequency.

3. Concept of Gain.

ULTRASONOGRAPHY

• Non-invasive, efficient and inexpensive diagnostic tool. • Examiner- dependent

• Expertise • A correlation with clinical findings is essential to make

a diagnosis..

• 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

• 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.

Apna B Scan

INSTRUMENTATION

• An USG unit is composed of four basic elements :

– Pulser,

– Receiver – Display screen – Transducer

B SCAN CONTROL PANEL

USE OF INCREASING GAIN

Use of Decreasing Gain

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

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.

REQUISITE 4 HIGH QUALITY BSCAN

1. Lesion Must be Placed in the centre

2. Beam must be directed perpendicular to the surface of interest

3. Lowest Possible decibel gain that is consistent with adequate mantainence of intensity and resolution of lesion.

ABOUT THE PROBE

• 1-5 MHZ = Abdominal USG• 8-10 MHZ = Ophthalmic USG• 50-100 MHZ = UBM

B Scan : Orientation & Labeling

1. Axial Section

2. Transverse Section

3. Longitudinal Section

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

Bscan in Various Pathologies

TOPOGRAPHIC EXAMn.

SHAPE

LOCATION

EXTENSION

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

References

• Most of the photographs and pics hav been taken from Textbook of Ophthalmic

Ultrasound by Hatem R. Aata WITHOUT PRIOR PERMISSION.

Correlation with clinical findings is essential to make a diagnosis

• THANK YOU EVERYONE FOR PATIENTLY LISTENING TO THIS SEMINAR.• For feedbacks & brickbats plz mail at• ykush@yahoo.co.in./drdhir2014@gmail.com

“ Thank you for listening B scan”