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Commencing the scan

Created: 5/4/2004
 

Click the following links for sections in this article

- Scanning basics
- Guided needle insertion techniques


 

1. Apply acoustic coupling gel

Apply Gel

Ultrasound will not travel through air at this frequency
A transmission gel is required to eliminate surface air

The gel should completely cover the scanhead membrane and may be applied to the patient's skin
An airfree layer of gel should be added inside the ends of any sheaths or sterile sleeves used in interventional procedures

Gel Biopsy 

2. Place transducer and obtain required view

Position the bed to a comfortable height
Position scanner for access to controls and clear view of screen
Hold the transducer comfortably using appropriate orientation
Use your little finger to determine how hard you are pressing
Lightly touch patient with heel of hand or little finger for stability

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3. Transducer orientation

The transducer notch/groove provides an orientation reference. By convention, the notch should point toward the patient's:

right side in transverse views
head in longitudinal views.

The side of the image corresponding with the notch end of the transducer is shown onscreen with a coloured orientation marker.

 

 

Transducer Notch


Transverse

 Transverse Arm

Longitudinal

Long Scan Long Arm

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Image presentation

Image Presentation

4. Optimise depth

Increasing the depth allows you to visualise deeper structures
Adjust the depth to maximise detail (typically the target vessel should be centred in the image)

Click here for depth optimisation example

(Click on the UP or DOWN buttons to find the optimal depth setting

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5. Optimise gain

Gain controls the brightness of the displayed image. As sound travels deeper, attenuation of the signal occurs. This is more pronounced with higher frequencies. Independent control of near-field and far-field gain settings is therefore needed to compensate for the progressive effect of depth-dependent attenuation. Note that too low a gain setting may result in a missed diagnosis. The gain should be increased until bright reflectors are white but do not bloom or oversaturate.

Gain Controls

Too low gain may result in missed diagnostic information. Too much gain may result in image oversaturation and obscured detail.
Near gain and far gain should be adjusted to provide a uniform image throughout the depth of field
Overall gain may be used to adjust the entire image equally.

Click here for gain optimisation example

(Use the UP and DOWN buttons below to change the overall gain control in our interactive flash movie example of a venous thrombus) 

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Guided needle insertion

Surgical Scan

Line Placement

1. Choose site

Arm Veins Avoid areas of flexion
Work distal to proximal
Vein choice:

Basilic - always attempt first
Brachial - can be paired
Cephalic - last resort (look at other arm first)

 

Vessels

2. Attach guide

Add gel inside sterile cover and attach needle guide

Transducer SleeveBiopsy Attachment

New transverse guide currently offered
Accepts 18, 21 and 22 gauge needles
Suitable for 1, 2 and 3 cm depths

3. Perform placement with visual guidance

Image Guided Insertion

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ArticleDate:20040405
SiteSection: Article
 
   
    
                                            
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