Apparatus and method for characterization of acute otitis media
An ultrasound signal processor uses an excitation generator to cause displacement of a tympanic membrane while a series of ultrasound pulses are applied to the tympanic membrane. Phase differences between a transmitted signal and received signal are examined to determine the movement of the tympanic membrane in response to the applied excitation. An examination of the phase response of the tympanic membrane provides a determination as to whether the fluid type behind the tympanic membrane is one of: no fluid, serum fluid, or purulent fluid.
1. A method for characterizing a tympanic membrane, the method comprising:
applying an excitation to the tympanic membrane to cause a displacement of the tympanic membrane, the excitation comprising a pressure modulation;
transmitting with a micro-machined ultrasound transducer transmit acoustic waves toward the tympanic membrane during a transmit interval;
receiving reflected acoustic waves from the tympanic membrane during a receive interval;
comparing a phase of the transmitted transmit acoustic waves to a phase of the received reflected acoustic waves;
generating a phase output in response to the comparison of the phases of the transmitted transmit acoustic waves and the received reflected acoustic waves;
comparing the phase output to the excitation; and
determining one or more of the displacement or a mobility of the tympanic membrane in response to the comparison of the phase output to the excitation.
2. The method of claim 1 , wherein the pressure modulation is an air puff.
3. The method of claim 1 , wherein the excitation is generated using a voice coil actuator or a moving diaphragm.
4. The method of claim 1 , wherein the pressure modulation has a sub-audio frequency below 20 Hz, an audio frequency from 20 Hz to 20 kHz, or a super-audio frequency above 20 kHz.
5. The method of claim 1 , wherein the excitation is generated using an excitation generator, and wherein the transmit acoustic waves are generated using a transducer distinct from the excitation generator.
6. The method of claim 1 , wherein the transmit acoustic waves comprise a continuous wave (CV) transmit signal or a pulsed transmit signal.
7. The method of claim 1 , wherein the transducer is a capacitive micro-machined ultrasound transducer (cMUT).
8. The method of claim 1 , wherein the micro-machined ultrasound transducer has a pulse repetition rate of less than 15 kHz.
9. The method of claim 1 , wherein the receive interval and the transmit interval are concurrent intervals of time.
10. The method of claim 1 , wherein the receive interval and the transmit interval are exclusive intervals of time.
11. The method of claim 1 , wherein the phase output is compared to the excitation over a plurality of sample points.
12. The method of claim 1 , wherein the phase output comprises an amplitude response of the received reflected acoustic waves.
13. The method of claim 12 , wherein one or more of the displacement, position, or mobility of the tympanic membrane is determined in response to the amplitude response.
14. The method of claim 1 , wherein the phase output comprises a time delay of the received reflected acoustic waves.
15. The method of claim 14 , wherein one or more of the displacement or mobility of the tympanic membrane is determined in response to the time delay.
16. The method of claim 1 , wherein the displacement of the tympanic membrane is a change in position of the tympanic membrane in response to the excitation.
17. The method of claim 1 , further comprising determining one or more of a viscosity of a fluid adjacent to the tympanic membrane in response to the comparison of the phase output to the excitation.
18. The method of claim 1 , further comprising determining an effusion metric of the tympanic membrane in response to the comparison of the phase output to the excitation, wherein the effusion metric distinguishes between no effusion, serum effusion, or purulent effusion.
19. The method of claim 1 , further comprising characterizing an ear of a patient as having a bacterial ear infection or a viral ear infection in response to the comparison of the phase output to the excitation.
20. The method of claim 1 , wherein the transmit acoustic waves are transmitted through an air medium.