# US 2013/0158387 A1 · Mri thermal imaging of water tissue and fat tissue using transverse relaxometry data and proton resonance frequency shift data

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- Number: US 2013/0158387 A1
- Document ID: US20130158387A1
- Status: Published application
- Kind: A1
- Application number: 13/817,912
- Filed: 2011-08-26
- Published: 2013-06-20
- Earliest claimed: 2010-08-30
- Assignees: Koninklijke Philips Electronics N.V.
- Inventors: Jukka Ilmari Tanttu
- Web page: https://patentgrep.com/patent/US20130158387A1

## CPC

- A61B 5/055: involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
- A61B 5/0036: {including treatment, e.g., using an implantable medical device, ablating, ventilating}
- A61B 5/01: Measuring temperature of body parts {; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue} (clinical contact thermometers G01K13/20)
- A61B 5/4836: {Diagnosis combined with treatment in closed-loop systems or methods (A61B5/0036 takes precedence)}
- A61B 5/4872: {Body fat}
- A61B 5/4875: {Hydration status, fluid retention of the body}
- A61B 5/7278: {Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals}
- A61B 18/1206: {Generators therefor}
- A61B 18/24: with a catheter (A61B18/26, A61B18/28 take precedence)
- A61N 7/02: Localised ultrasound hyperthermia
- G01R 33/4804: {Spatially selective measurement of temperature or pH}
- G01R 33/4828: {Resolving the MR signals of different chemical species, e.g. water-fat imaging}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

An apparatus (300, 400, 500) comprising a magnetic resonance imaging system (302), the magnetic resonance imaging system comprising: a magnet (306) adapted for generating a magnetic field for orientating the magnetic spins of nuclei of a subject (310) located within an imaging volume (308); a radio frequency transceiver (320) adapted for acquiring magnetic resonance data (346) using a radio frequency coil (318); a computer system (336) comprising a processor (338), wherein the computer system is adapted for controlling the apparatus; and a memory (342, 344) containing machine readable instructions (354, 356, 358, 360, 362), wherein execution of the instructions cause the processor to perform the steps of: acquiring (100, 204) magnetic resonance data using the magnetic resonance imaging system, wherein the magnetic resonance data comprises transverse relaxometry data, and calculating (102, 206) the temperature of the subject within a temperature measurement volume (332) in accordance with the transverse relaxometry data.

## Claims

### Claim 1

An apparatus comprising a magnetic resonance imaging system, the magnetic resonance imaging system comprising:
a magnet adapted for generating a magnetic field for orientating the magnetic spins of nuclei of a subject located within an imaging volume;
a radio frequency transceiver adapted for acquiring magnetic resonance data using a radio frequency coil;
a magnetic field gradient coil adapted for spatial encoding of the magnetic spins of nuclei within the imaging volume;
a magnetic field gradient coil power supply adapted for supplying current to the magnetic field gradient coil;
a computer system comprising a processor, wherein the computer system is adapted for controlling the apparatus; and
a memory containing machine readable instructions for execution by the processor, wherein execution of the instructions cause the processor to perform the steps of:
acquiring magnetic resonance data using the magnetic resonance imaging system, wherein the magnetic resonance data comprises transverse relaxometry T2 or T2 star data, as well as proton resonance frequency shift data, wherein at least the transverse relaxometry T2 or T2 star data is acquired using a turbo spin echo (TSE) sequence, and
calculating the temperature of the subject within a temperature measurement volume in accordance with the transverse relaxometry T2 or T2 star data, in combination with calculating the temperature of the subject within the temperature measurement in accordance with the proton resonance frequency shift data, wherein the temperature measurement volume is within the imaging volume.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the machine readable instructions include to interleave the acquisition of the transverse relaxometry data with the acquisition of the proton resonance frequency shift data.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein the machine readable instructions include to repeatedly measure or monitor the temperature and to update the proton resonance frequency shift data more often than transverse relaxometry data.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein the acquisition of the transverse relaxometry data involves a fat-selective excitation and the temperature measurement in accordance with the proton resonance frequency shift data involves a water-selective excitation.

### Claim 5 (depends on 1)

The apparatus of claim 1 in which the acquisition of the transverse relaxometry data involves a repetition time that is longer than the longitudinal relaxation time (T1) of the tissue in the measurement volume.

### Claim 6 (depends on 1)

The apparatus of claim 1 in which the acquisition of the transverse relaxometry data involves a gradient echo sequence with a low flip angle, in particular less than 30° or less than 5°.

### Claim 7 (depends on 1)

The apparatus of claim 1, wherein the therapeutic apparatus further comprises a tissue heating system for heating a target volume of the subject, wherein the target volume is within the imaging volume, and wherein the computer system is further adapted for controlling the tissue heating system.

### Claim 8 (depends on 7)

The therapeutic apparatus of claim 7, wherein the tissue heating system is any one of the following: a high intensity focused ultrasound system for sonicating the target volume, a radio frequency tissue heating system for heating the target volume with radio frequency energy, and a laser ablation system for ablating tissue within the target volume.

### Claim 9 (depends on 7)

The apparatus of claim 7, wherein the instructions further cause the processor to perform the steps of:
receiving a treatment plan specifying the target volume within the imaging volume, wherein the treatment plan comprises instructions for controlling the operation of the tissue heating system;
heating the target volume using the tissue heating system by executing the treatment plan;
acquiring repeatedly magnetic resonance data using the magnetic resonance imaging system during execution of the treatment plan;
calculating repeatedly the temperature of the subject within the temperature measurement volume; and
modifying the treatment plan during execution of the treatment in accordance with the temperature within the temperature measurement volume.

### Claim 10 (depends on 1)

The apparatus of claim 1, wherein the memory contains a pulse sequence for controlling the operation of the magnetic resonance imaging system, wherein the pulse sequence is an inversion recovery T2 weighted turbo spin echo sequence, wherein the pulse sequence is adapted for acquiring both the transverse relaxometry T2 or T2 star data and longitudinal relaxometry T1 data by using an inversion time which is short in comparison to the T1 relaxation time.

### Claim 11 (depends on 7)

The apparatus of claim 7, wherein the temperature of each of the temperature measurement volumes associated with the transverse relaxometry T2 or T2 star data, and the proton resonance frequency shift data, respectively is determined individually in accordance with any one of the following: the transverse relaxometry data and the proton resonance frequency shift data.

### Claim 12 (depends on 1)

The apparatus of claim 1, wherein execution of the instructions further causes the processor to perform the steps of:
constructing a temperature map in accordance with the temperature measurement volumes;
reconstructing a magnetic resonance image in accordance with the magnetic resonance data; and
displaying a thermal magnetic resonance image on a display by superimposing the temperature map on the magnetic resonance image.

### Claim 13

(canceled)

### Claim 14

A computer-implemented method of acquiring magnetic resonance thermometry data, the method comprising the steps of:
acquiring (100, 204) magnetic resonance data (346) using a magnetic resonance imaging system (302) to implement a turbo spin echo (TSE) sequence, wherein the magnetic resonance data comprises transverse relaxometry T2 or T2 star data as well as proton resonance frequency shift data, and
calculating (102, 206) the temperature of a subject (310) within a temperature measurement volume (332) in accordance with the transverse relaxometry T2 or T2 star data in combination with calculating the temperature of the subject within the temperature measurement in accordance with the proton resonance frequency shift data, wherein the temperature measurement volume is within an imaging volume (308) of the magnetic resonance imaging system.

### Claim 15

A computer program product comprising machine executable instructions (354, 356, 358, 360, 362) for execution by a processor (338) of a computer system (336) of an apparatus (300, 400, 500) comprising a magnetic resonance imaging system (306);
wherein execution of the instructions cause the processor to perform the steps of:
acquiring (100, 204) magnetic resonance data using the magnetic resonance imaging system to implement a turbo spin echo (TSE) sequence, wherein the magnetic resonance data comprises transverse relaxometry T2 or T2 star data as well as proton resonance frequency shift data; and
calculating (102, 206) the temperature of a subject (310) within a temperature measurement volume (332) in accordance with the transverse relaxometry T2 or T2 star data in combination with calculating the temperature of the subject within the temperature measurement in accordance with the proton resonance frequency shift data, wherein the temperature measurement volume is within an imaging volume (308) of the magnetic resonance imaging system.