Ultrasound Safety and Recent Advances

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ULTRASOUND SAFETY AND RECENT ADVANCES Dr. Varun Babu MD Resident Dept. of Radiology AIMS, Cochin June 9, 2011

Ultrasound Safety : 

No study has shown any damaging effect of pulsed US at diagnostic intensities when applied to the intact fetus in utero There is no place in medicine for a ‘quick (inadequate) ultrasound’, or for ‘just to have a look’ (e.g. at a fetus) European Federation of Societies for Ultrasound in Medicine and Biology www.efsumb.org Ultrasound Safety

Safety – some terms : 

Ultrasound intensity Energy flowing across a surface in unit time (W/cm2) B mode imaging ~ 175 m W/cm2 Spectral Doppler ~ 1600 m W/cm2 2 indices Mechanical Index (MI) Probability of mechanically induced damage MI of 1 warns possible damage Thermal Index (TI) Heating of tissues TIS and TIB TIS of 1 = tissue gets heated to a max. of 10C Safety – some terms

3D Ultrasound : 

3D Ultrasound

3D and 4D Ultrasonography : 

Data can be acquired rapidly enough to allow display in real-time at low frame rates Display of complex anatomy like fetal face and the heart Most parts of the body don’t have clean surfaces for 3D rendering However reslicing in other planes help in some situations Viewing uterus in coronal plane for developmental anomalies 3D and 4D Ultrasonography

Elastography : 


Elastography : 

Elasticity imaging – offers high contrast between tumors and host tissue Principle: obtain signals before and after applying a distorting force that creates an image of the tissue’s response (strain) Role in breast and prostate The need for antiviral therapy in hepatitis – assessed by measuring the liver elasticity (a measure of fibrosis) Elastography

Contrast Ultrasound - Hemangioma : 

Contrast Ultrasound - Hemangioma

Contrast Sonography : 

‘Microbubble’ agents to enhance US signals – perfluorocarbons Allows continuous imaging for 5min after injection Stabilized by encapsulating in a membrane – denatured albumin or phospholipid Contrast Sonography

Atherosclerotic plaque : 

Atherosclerotic plaque

Stroke : 


Contrast Sonography - Uses : 

Demonstrate tissue perfusion at infarction sites Identify bleeding points Encorporated into European guidelines for hepatoma detection in cirrhosis As tracers – like radioisotope studies Role in cardiac perfusion studies (negative bolus) Therapeutic: vehicles for DNA, olignoucleotides Contrast Sonography - Uses

Ultrasound Therapy : 

Ultrasound Therapy

Ultrasound therapy : 

Tissue ablative therapy in oncology Principle: Thermal energy Similar to a radiotherapy approach but has more advantages More precise, rapid Easy to handle, no damage to adjacent tissues Can monitor effects with realtime ultrasound Disadvantage Usual limitations of US Ultrasound therapy

Slide 16: 

This has been an attempt to just introduce the basics of ultrasound physics. Try to correlate as you acquire the skills Thank you 

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