# US 11,896,422 B2 · Systems and method for performing pulse wave velocity measurements

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- Number: US 11,896,422 B2
- Document ID: US11896422B2
- Status: Granted
- Kind: B2
- Application number: 17/269,672
- Filed: 2019-08-13
- Published: 2021-11-04
- Granted: 2024-02-13
- Earliest claimed: 2018-08-21
- Assignees: Koninklijke Philips N.V.
- Applicants: Koninklijke Philips N.V.
- Inventors: Maarten Petrus Joseph Kuenen; Arjen Van Der Horst
- Web page: https://patentgrep.com/patent/US11896422B2

## CPC

- A61B 8/06: Measuring blood flow
- A61B 8/12: in body cavities or body tracts, e.g. by using catheters
- A61B 8/4494: {characterised by the arrangement of the transducer elements}
- A61B 8/488: {involving Doppler signals}
- G01S 7/52066: {Time-position or time-motion displays}
- G01S 15/8915: {using a transducer array}
- G01S 15/8979: {Combined Doppler and pulse-echo imaging systems}
- A61B 5/02007: {Evaluating blood vessel condition, e.g. elasticity, compliance}
- A61B 5/02108: {from analysis of pulse wave characteristics}
- A61B 5/0285: Measuring or recording phase velocity of blood waves
- A61B 8/0891: {for diagnosis of blood vessels}
- A61B 8/4488: {the transducer being a phased array}
- G01S 7/5208: {with integration of processing functions inside probe or scanhead}
- G01S 15/8925: {the array being a two-dimensional transducer configuration, i.e. matrix or orthogonal linear arrays}
- G01S 15/8993: {Three dimensional imaging systems}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

The invention provides a system and a method for calculating a pulse wave velocity based on a plurality of intravascular ultrasonic pulses directed along a vessel. For each ultrasonic pulse, a plurality of echoes is received from a plurality of distances along the vessel. A first ultrasound Doppler signal is received from a first distance from the pulse origin and a second ultrasound Doppler signal from a second distance from the pulse origin. A first and second flow velocity metric is obtained based on the first and second ultrasound Doppler signal, respectively. The pulse wave velocity is calculated based on the time delay, which is based on the first flow velocity metric and the second flow velocity metric.

## Claims

### Claim 1

A system for performing intravascular pulse wave velocity measurements, the system comprising:
an intravascular ultrasound device adapted to:
generate, using a single sensor, a plurality of intravascular ultrasonic pulses at a pulse origin, wherein the plurality of intravascular ultrasonic pulses are directed along a vessel;
for each of the plurality of intravascular ultrasonic pulses, receive a plurality of echoes from a plurality of distances relative to the pulse origin, using the single sensor; and
a processor adapted to:
obtain a first ultrasound Doppler signal from a first distance relative to the pulse origin based on a plurality of echoes;
identify a change in velocity at the first distance based on the first ultrasound Doppler signal;
obtain a second ultrasound Doppler signal from a second distance relative to the pulse origin based on the plurality of echoes;
identify the change in velocity at the second distance based on the second ultrasound Doppler signal;
determine a time delay based on the change in velocity at the first distance and the change in velocity at the second distance, wherein the time delay corresponds to a time for the change in velocity to propagate from the first distance to the second distance;
calculate a pulse wave velocity based on the time delay; and
provide an output based on the pulse wave velocity to a display.

### Claim 2 (depends on 1)

The system according to claim 1, wherein the single sensor comprises:
a single ultrasound transducer element; or an array of ultrasound transducer elements.

### Claim 3 (depends on 1)

The system of claim 1, wherein, to determine the time delay, the processor is adapted to perform cross-correlation between the first ultrasound Doppler signal and the second ultrasound Doppler signal.

### Claim 4 (depends on 1)

The system of claim 1, wherein, to identify the change in velocity at the first distance, the processor is adapted to obtain a first flow velocity metric based on the first ultrasound Doppler signal, and wherein, to identify the change in velocity at the second distance, the processor is adapted to obtain a second flow velocity metric based on the second ultrasound Doppler signal.

### Claim 5 (depends on 4)

The system of claim 4, wherein the first flow velocity metric comprises a first average velocity and the second flow velocity metric comprises a second average velocity.

### Claim 6 (depends on 4)

The system of claim 4, wherein the first flow velocity metric comprises a first distribution of flow velocities and the second flow velocity metric comprises a second distribution of flow velocities.

### Claim 7 (depends on 6)

The system of claim 6, wherein the first distribution of flow velocities comprises a first frequency spectrum and the second distribution of flow velocities comprises a second frequency spectrum.

### Claim 8 (depends on 6)

The system of claim 6, wherein, to determine the time delay, the processor is adapted to:
for each velocity value of the first distribution of flow velocities and second distribution of flow velocities, calculate an individual time delay of a plurality of individual time delays; and
calculate an average time delay based on the plurality of individual time delays.

### Claim 9 (depends on 6)

The system of claim 6,
wherein, to identify the change in velocity at the first distance, the processor is adapted to extract a first feature of the first distribution of flow velocities;
wherein, to identify the change in velocity at the second distance, the processor is adapted to extract a second feature of the second distribution of flow velocities; and
wherein, to determine the time delay, the processor is adapted to:
calculate the time delay based on the first feature and the second feature.

### Claim 10 (depends on 9)

The system of claim 9, wherein the first and second feature comprises one or more of:
an instantaneous peak velocity;
a pulse onset;
a peak time;
a maximum acceleration; and
an instantaneous average velocity.

### Claim 11 (depends on 6)

The system of claim 6, wherein, to determine the time delay, the processor is adapted to perform cross-correlation between the first distribution of flow velocities and the second distribution of flow velocities.

### Claim 12 (depends on 1)

The system of claim 1, wherein the system is further configured to obtain a pressure metric and wherein the calculation of the pulse wave velocity is based on the time delay and the pressure metric.

### Claim 13 (depends on 1)

The system according to claim 1, wherein the processor is adapted to use electronic beam steering and/or electronic beam focusing to control the intravascular ultrasound device to generate the plurality of intravascular ultrasonic pulses.

### Claim 14

A method of calculating a pulse wave velocity, the method comprising:
generating, using a single sensor, a plurality of intravascular ultrasonic pulses at a pulse origin, wherein the plurality of intravascular ultrasonic pulses are directed along a vessel;
for each of the plurality of intravascular ultrasonic pulses, receiving a plurality of echoes from a plurality of distances relative to the pulse origin, using the single sensor;
obtaining a first ultrasound Doppler signal from a first distance relative to the pulse origin based on a plurality of echoes;
identifying a change in velocity at the first distance based on the first ultrasound Doppler signal;
obtaining a second ultrasound Doppler signal relative to a second distance from the pulse origin based on the plurality of echoes;
identifying the change in velocity at the second distance based on the second ultrasound Doppler signal;
determining a time delay based on the change in velocity at the first distance and the change in velocity at the second distance, wherein the time delay corresponds to a time for the change in velocity to propagate from the first distance to the second distance;
calculating a pulse wave velocity based on the time delay; and
outputting the pulse wave velocity to a display.

### Claim 15 (depends on 1)

A non-transitory computer-readable storage medium comprising a computer program which is adapted, when said computer program is run on a computer, to implement a method of calculating a pulse wave velocity on a system according to claim 1.