Dispersive Ultrasound Technology as a Diagnostic Device for Traumatic Brain Injuries

• US 20130225998A1
• Filed: 02/28/2012
• Published: 08/29/2013
• Est. Priority Date: 02/28/2012
• Status: Active Grant

• Current Assignee: Her Majesty The Queen In Right of Canada As Represented By The Minister of National Defence
• Original Assignee: Her Majesty The Queen In Right of Canada As Represented By The Minister of National Defence
• Inventors: Stergiopoulos, Stergios, Freibert, Andreas, Zhang, Jason
• Granted Patent: US 8,834,376 B2
• Time in Patent Office: Days
• US Class Current: 600/442
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: A61B 8/0808 for diagnosis of the brain
• CPC Class Codes: A61B 8/0858 involving measuring tissue layers, e.g. skin, interfaces
• CPC Class Codes: G01N 2291/048 Transmission, i.e. analysed material between transmitter and receiver

Abstract

Described herein is the use of ultrasound pulses at different frequencies to track the dispersion properties of intracranial tissues which may have been altered due to traumatic or other neurological brain injury. Dispersive ultrasound does not provide imaging, but it can provide data of significant diagnostic value by using decision support systems that can be trained as a medical diagnostic system for traumatic brain injuries applications to detect specific patterns of dispersion that are associated with specific intracranial injuries.

Claims

1. A method of identifying an unknown medium comprising:

a) interrogating an unknown medium with a plurality of ultrasound pulses at different frequencies;

b) identifying individual signals by pulse duration, center frequency and bandwidth;

c) estimating the propagation time through the medium for a first ultrasound frequency using cross correlation;

d) improving the estimate of the propagation time by determining zero phase crossing using linearity of phase;

e) repeating steps (b)-(d) for all frequencies;

f) using information derived from ultrasound pulses to generate an ultrasonic fingerprint of the medium; and

g) identifying the medium based on characteristics of the fingerprint.

2. The method according to claim 1 including at step (b) applying a temporal window to the signal.

3. The method according to claim 1 wherein the ultrasound signal is a broadband frequency modulated signal.

4. The method according to claim 3 wherein each signal has a bandwidth of about 0.5 MHz.

5. The method according to claim 1 including applying FIR filters to the cross correlation data.

6. The method according to claim 1 wherein the phase information is calculated by Hilbert transformation.

7. The method according to claim 1 wherein the ultrasound fingerprint is compared to a database of fingerprints of known media and the unidentified medium is identified based on said comparison.

8. The method according to claim 1 wherein the medium is intracranial tissues.

9. The method according to claim 8 wherein frequencies are between 500 kHz and 10 MHz.

10. The method according to claim 8 wherein the medium is intracranial tissues which are suspected of having been altered by a brain injury.

11. The method according to claim 10 wherein frequencies are between 500 kHz and 10 MHz.

12. The method according to claim 8 wherein the database comparison is carried out by a support vector machine.