WO2015197720A1

WO2015197720A1 - Mri system with wireless synchronization of a wireless rf coil portion using a double sideband suppressed carrier signal

Info

Publication number: WO2015197720A1
Application number: PCT/EP2015/064297
Authority: WO
Inventors: Arne Reykowski
Original assignee: Koninklijke Philips N.V.
Priority date: 2014-06-25
Filing date: 2015-06-24
Publication date: 2015-12-30

Abstract

A magnetic resonance system having a system clock, the system including: at least one controller which: forms pilot and carrier signals, the pilot signal formed in accordance with at least the system clock, and wirelessly transmits a dual sideband suppressed carrier (DSB-SC) signal based upon a product of the pilot and carrier signals; and a wireless-type radio-frequency (RF) coil portion which: receives the DSB-SC signal, recovers the pilot and carrier signals from the received DSB-SC signal, and sets a clock of the RF portion in accordance with the recovered pilot signal.

Description

MRI SYSTEM WITH WIRELESS SYNCHRONIZATION OF A WIRELESS RF COIL PORTION USING A DOUBLE SIDEBAND SUPPRESSED CARRIER SIGNAL

The present system relates to a magnetic resonance imaging (MRI) system with a wireless-type radio-frequency (RF) coil portion with enhanced accuracy and a method of operation thereof.

MRI is an imaging method that generally uses frequency and phase encoding of protons for image reconstruction. Recently, MRI systems have begun to use wireless- type RF coil (hereinafter wireless RF coils), which typically employ an internal receiver clock. Wireless RF coils acquire analog MR information during an acquisition period and thereafter reconstruct the analog MR information to form digitized information, such as digitized image information. Thereafter, the wireless RF coils provide the digitized information to a system controller for further processing and/or display on a display of the MRI system. Wireless RF coils rely upon an internal receiver clock for correct synchronization with a system clock (e.g., a master clock). However, because of the wireless nature of wireless RF coils and induced RF noise, it is often difficult to accurately synchronize the receiver clock with the system clock using conventional wireless communication methods. Unfortunately, when the receiver clock is not accurately synchronized with the system clock, phase noise of the receiver clock can cause image artifacts in reconstructed images due to the nature of an encoding method being used, particularly during long acquisitions.

Accordingly, embodiments of the present system overcome the above- mentioned shortcomings of prior art systems.

Further, embodiments of the present system may provide a receiver clock that can reduce or otherwise minimize phase noise such as RMS phase error on a digitized signal. For example, if it is required that clock-induced RMS phase error in image raw data remain below 1 degree, then the RMS time jitter should be controlled to remain below 44 picoseconds (ps) at 64MHz and below 22 ps at 1 28MHz.

The system(s), device(s) , method(s), user interface(s) , computer program(s), processes, etc. (hereinafter each of which will be referred to as system, unless the context indicates otherwise) , described herein address problems in prior art systems.

In accordance with embodiments of the present system, there is provided a magnetic resonance system having a system clock, the system comprising: at least one controller which: forms pilot and carrier signals, the pilot signal formed in accordance with at least the system clock, and wirelessly transmits a dual sideband suppressed carrier (DSB-SC) signal based upon a product of the pilot and carrier signals; and a wireless-type radio-frequency (RF) coil portion which: receives the DSB-SC signal, recovers the pilot and carrier signals from the received DSB-SC signal, and sets a clock of the RF portion in accordance with the recovered pilot signal. In accordance with embodiments of the present system, the at least one controller may determine an operating state to set for the wireless-type RF coil portion. The at least one controller may modulate the pilot signal in accordance with the determined operating state. The at least one controller may modulate the pilot signal using at least one of a Binary Phase Shift Keying (BPSK) method and Multiple Frequency Shift Keying (MFSK) method. The MRI system of claim 1 , wherein the wireless-type RF coil portion further identifies at least one recovered pilot tone from the recovered pilot signal. The wireless-type RF coil portion may determine an operating state of the wireless-type RF coil portion in accordance with the identified at least one recovered pilot tone from the recovered pilot signal.

In accordance with embodiments of the present system, the MRI system may further comprise a memory. The wireless-type RF coil portion: may acquire echo information; form digitized information comprising the acquired echo information and at least a synchronous portion of the received DSB-SC signal; and store the digitized information in the memory. The at least one controller may further: obtain the digitized information from the memory; extract a clock synchronization signal from the digitized information; and reconstruct the digitized information in accordance with the extracted clock synchronization signal.

In accordance with embodiments of the present system, a wireless synchronization method is provided for a magnetic resonance (MR) system having a system clock, and a wireless-type radio-frequency (RF) coil portion, the method performed by at least one controller of the MR imaging system and comprising acts of: forming pilot and carrier signals, the pilot signal formed in accordance with at least the system clock; wirelessly transmitting a dual sideband suppressed carrier (DSB-SC) signal which is based upon a product of the pilot and carrier signals; receiving, by the wireless- type RF coil portion, the DSB-SC signal; recovering, by the wireless-type RF coil portion, the pilot and carrier signals from the received DSB-SC signal, and setting, by the wireless-type RF coil portion, a clock of the wireless-type RF coil portion in accordance with the recovered pilot signal.

In accordance with embodiments of the present system, the method may further comprise an act of determining an operating state to set for the wireless-type RF coil portion. The method may further comprise an act of modulating the pilot signal in accordance with the determined operating state. The method may further comprise an act of modulating the pilot signal using at least one of a Binary Phase Shift Keying (BPSK) method and Multiple Frequency Shift Keying (MFSK) method. The method may further comprise an act identifying, by the wireless-type RF coil portion, at least one recovered pilot tone from the recovered pilot signal. The method may further comprise an act of determining an operating state of the wireless-type RF coil portion in accordance with the identified at least one recovered pilot tone from the recovered pilot signal.

In accordance with embodiments of the present system, the method may further comprise acts of: acquiring, by the wireless-type RF coil portion, echo information; forming digitized information comprising the acquired echo information and at least a synchronous portion of the received DSB-SC signal; and storing the digitized information in a memory. The method may further comprise acts of: obtaining, by the at least one controller, the digitized information from the memory; extracting a clock synchronization signal from the digitized information; and reconstructing the digitized information in accordance with the extracted clock synchronization signal.

In accordance with embodiments of the present system, a computer readable non-transitory memory medium is provided including instructions stored thereon, which, when executed by at least one controller, configures one or more of the at least one controller to perform a method of synchronizing a magnetic resonance system having a system clock and a wireless-type radio-frequency coil portion, the method comprising acts of: forming pilot and carrier signals, the pilot signal formed in accordance with at least the system clock; wirelessly transmitting a dual sideband suppressed carrier (DSB- SC) signal which is based upon a product of the pilot and carrier signals; receiving, by the wireless-type RF coil portion, the DSB-SC signal; recovering, by the wireless-type RF coil portion, the pilot and carrier signals from the received DSB-SC signal, and setting, by the wireless-type RF coil portion, a clock of the wireless-type RF coil portion in accordance with the recovered pilot signal.

In accordance with embodiments of the present system, the instructions may configure one or more of the at least one controller to perform an act of determining an operating state to set for the wireless-type RF coil portion. The instructions may configure one or more of the at least one controller to perform an act of modulating the pilot signal in accordance with the determined operating state. The instructions may configure one or more of the at least one controller to perform an act of identifying, by the wireless-type RF coil portion, at least one recovered pilot tone from the recovered pilot signal.

The invention is explained in further detail, and by way of example, with reference to the accompanying drawings wherein:

FIG. 1 shows a cutaway side view of a portion of an MR system operating in accordance with embodiments of the present system;

FIG. 2 shows a schematic block diagram of a portion of a PLL clock synchronizer using a single pilot carrier input as a wireless synchronization signal in accordance with embodiments of the present system;

FIG. 3 shows a schematic block diagram of a portion of a Costas loop-type clock synchronizer using a single pilot carrier input in accordance with embodiments of the present system;

FIG. 4 shows a schematic block diagram of a portion of a synchronizer in accordance with embodiments of the present system;

FIG. 5 shows a graph of a spectrum plot of a DSB-SC signal generated in accordance with embodiments of the present system;

FIG. 6 shows a schematic block diagram of a portion of a synchronizer including a mixer for mixing a single pilot signal (PS) and a carrier signal (CS) to form a modulated signal (MS) in accordance with embodiments of the present system;

FIG. 7 shows a graph of an output spectrum of the modulated signal (MS) in accordance with embodiments of the present system; FIG. 8 shows a schematic block diagram of transmission and reception of a DSB- SC synchronization signal, such as a modulated signal (MS), over a wireless channel in accordance with embodiments of the present system;

FIG. 9 which shows a schematic block diagram of a portion of an MR system with a wireless-type RF portion in accordance with embodiments of the present system;

FIG. 10 shows an enhanced pilot tone spectrum of a recovered pilot signal (PSr) in accordance with embodiments of the present system;

FIG. 1 1 A shows a graph of an enhanced spectrum for entering a first RF operating state in accordance with embodiments of the present system;

FIG. 1 1 B shows a graph of an enhanced spectrum for entering a second RF operating state in accordance with embodiments of the present system;

FIG. I I C shows a graph of an enhanced spectrum for entering a third RF operating state in accordance with embodiments of the present system;

FIG. 1 1 D shows a graph of an enhanced spectrum for entering a fourth RF operating state in accordance with embodiments of the present system;

FIG. 12 shows a graph of a combined spectrum including a Center DSB-SC signal and an MRI signal in accordance with embodiments of the present system; and

FIG. 13 shows a portion of a system (e.g., peer, server, etc.) in accordance with embodiments of the present system;

FIG. 14 shows a schematic block diagram of a portion of digital Costas loop clock synchronizer in accordance with embodiments of the present system; and

FIG. 15 shows a schematic block diagram of a portion of digital Costas loop-type clock synchronizer in accordance with embodiments of the present system.

The following are descriptions of illustrative embodiments that when taken in conjunction with the following drawings will demonstrate the above noted features and advantages, as well as further ones. In the following description, for purposes of explanation rather than limitation, illustrative details are set forth such as architecture, interfaces, techniques, element attributes, etc. However, it will be apparent to those of ordinary skill in the art that other embodiments that depart from these details would still be understood to be within the scope of the appended claims. Moreover, for the purpose of clarity, detailed descriptions of well known devices, circuits, tools, techniques and methods are omitted so as not to obscure the description of the present system. It should be expressly understood that the drawings are included for illustrative purposes and do not represent the entire scope of the present system. In the accompanying drawings, like reference numbers in different drawings may designate similar elements. The term and/or and formatives thereof should be understood to mean that only one or more of the recited elements may need to be suitably present (e.g., only one recited element is present, two of the recited elements may be present, etc., up to all of the recited elements may be present) in a system in accordance with the claims recitation and in accordance with one or more embodiments of the present system. Similarly while terms such as "the plurality", "each of the plurality", "all of the plurality", "all ..." etc., and formatives thereof are illustratively used herein, these terms and formatives should be understood to mean that only two or more of the recited elements may need to be suitably present, performed, etc. (e.g., in a case wherein there are four coils, the plurality of coils may refer to only two of the four coils, three of the four coils, etc., up to all of the four coils) in a system in accordance with the claims recitation and in accordance with one or more embodiments of the present system.

FIG. 1 shows a cutaway side view of a portion of an MR system 1 00 (hereinafter system 1 00 for the sake of clarity) operating in accordance with embodiments of the present system. The system 1 00 may include one or more of a controller 1 1 0, a memory, a display, a body 1 02, a main magnet 1 04, gradient coils 1 06, and an RF portion 1 20. A patient support 1 40 may be provided to support an object-of-interest (OOI) such as a patient 1 01 (hereinafter patient for the sake of clarity) and/or to position the patient 1 01 in a desired position and/or orientation in relation to the body 1 02 under the control of a user and/or the controller 1 1 0.

The body 1 02 may include at least one cavity 1 08 and a main bore 1 1 2 situated between opposed ends 1 1 4. The main bore 1 1 2 may be situated between opposed openings 1 1 5 of the body 1 02 and may be configured to receive the patient 1 01 through one of the opposed openings 1 1 5. The at least one cavity 1 08 may be configured to receive one or more of the main magnet 1 04, the gradient coils 1 06, and at least a portion of the RF portion 1 20 (e.g., an MRI receiver coil) . The body 1 02 may further include a cooling mechanism (e.g., a cryogenic cooling system, etc.) configured to cool portions of the system 1 00 such as the main magnet 1 04, if desired.

The controller 1 1 0 may control the overall operation of the system 1 00 and may include one or more logic devices such as processors (e.g., micro-processors, etc.) etc. The controller 1 10 may include one or more of a main magnet controller, a gradient controller, an RF controller, a system clock synchronizer 1 1 1 , and a reconstructor. The main magnet controller may control the operation of the main magnet 104. The gradient controller may control the operation of the gradient coils 106. The RF controller may control the operation of the RF portion 120. The system clock synchronizer 1 1 1 may be operative to wirelessly synchronize one or more clocks of the system such as the system clock (system clock) and an internal clock (int. clock) of the RF portion 120 which may be known as an RF clock (e.g., an MRI receiver coil clock) using methods operating in accordance with embodiments of the present system. The reconstructor may be operative to reconstruct analog information such as echo information and/or form corresponding image information which may be further processed, stored in a memory of the system for later use, and/or rendered on a display of the system for the convenience of the user. In accordance with embodiments of the present system, the analog information may be digitized and stored in a memory of the system for later processing such as for later reconstruction and rendering. This digitized information may be referred as raw digitized information and may, in some embodiments, include at least a portion of a synchronously-recorded recovered modulated signal (MSr) as will be discussed elsewhere.

The controller 1 10 may further determine or otherwise obtain scan sequences, scan parameters, etc. from a user and/or from the memory and apply them during a scanning procedure. For example, the controller 1 10 may obtain a scan sequence from the memory and, for example, control one or more of the main magnet 104, the gradient coils 106 and/or RF portion 120 in accordance with the scanning sequence to obtain, for example, desired magnetic resonance (MR) information such as echo information (e.g., analog MR information). The controller 1 10 may include at least one controller such as system controller and may be formed integrally with, or separately from, the body 102. For example, in some embodiments, the controller 1 10 may be remotely located from the body 102. Further, one or more portions of the controller 1 10 may be formed integrally with each other and/or remotely from (e.g., distributed) each other. The controller 1 10 and/or portions thereof, may communicate with one or more of the memory, the display, the main magnet 104, the gradient coils 106, and the RF portion 120 via any suitable method such as via wired and/or wireless communication methods, via one or more networks (e.g., a wide area network (WAN) , a local area network (LAN) , the Internet, a proprietary communication bus, a controller area network (CAN) , a telephony network, etc.

The main magnet 104 may have a bore 1 13 and may be configured to generate a main magnetic field (e.g., a Bo field) within the main bore 1 12. The main magnetic field may be substantially homogenous within a scanning volume of the main bore 1 12. The main magnet 104 may include one or more main magnets each configured to generate at least a portion of a main magnetic field. The main magnet 104 may be an annular (e.g., ring) magnet. However, in yet other embodiments, the main magnet may include any suitable magnet or magnets such as an annular or ring magnet, a planar magnet, a split magnet, an open magnet, a semicircular magnet (e.g., a C- shaped magnet, etc. The main magnet 1 04 or portions thereof may be formed from any suitable material such as a superconducting material and/or may operate under the control of the controller 1 10.

The gradient coils 1 06 may include one or more gradient coils (e.g., x-, y-, and z- gradient coils) which may produce one or more gradient fields along one or more corresponding axes under the control of the controller 1 1 0. The RF portion 1 20 may include a plurality of RF coils configured to transmit RF excitation pulses and/or receive (e.g., induced) MR signals (e.g., echo information, analog MR information) under the control of a controller such as the controller 1 1 0. For example, in some embodiments, the RF portion 1 20 may include a transducer array of transmission and/or reception coils. The RF portion 120 may be situated within the main bore 1 1 2 of the body 102 and may be placed in a desired position and/or orientation such as under the patient support 1 40 to obtain images of a desired scanning volume within the main bore 1 1 2. The RF portion 1 20 may include an RF clock which may be wirelessly synchronized to the system clock in accordance with embodiments of the present system. The RF clock may provide one or more signals to control the timing of the RF portion 1 20. For example, operations of the RF portion 1 20 may be timed in accordance with the RF clock.

The RF portion 1 20 may include one or more transmit and/or receive loops (such as a receive loop array) . For example, a detune switch portion may be associated with each transmit and/or receive loop, a power storage portion (to supply power to the RF portion 1 20), and a processing portion. Each loop may include a conductive radio- frequency (RF) coil configured†o resonate at one or more desired frequencies.

In accordance with embodiments of the present system, the RF coil portion 1 20 may have two or more operative states (e.g., modes) such as a tune state and a detune state. In the tune state, the detune switch portion may be operative to tune the one or more receive loops so that they may acquire MR signals (hereinafter echo information for the sake of clarity) . Thereafter, regardless of state, the RF portion 1 20 may locally sample the echo information and digitize the sampled echo information so as to form corresponding digital data (e.g., k-space data) . The digital data may then be reconstructed to form reconstructed MR information such as image information, spectrographs information, location information (e.g., for MR guided interventional procedures), etc., within the RF portion 1 20 or external to the RF portion 120 (e.g., at the controller 1 10) . The digital data and/or the reconstructed MR information may be transmitted from the RF portion 1 20 using any suitable wireless communication method or methods. For example, the digital data may be transmitted to the controller 1 1 0 via a wireless channel. In accordance with embodiments of the present system, by using wireless communication methods, the use of galvanic conductors such as RF cables may be avoided. In the detune state, the detune switch portion may be configured to detune the receive loops using any suitable method to protect sensitive circuitry which may be damaged by large currents induced in the receive loops. Further, when the switch portion detunes the receive loops, the switch portion may wirelessly harvest induced energy from the receive loops and/or store this energy in the power storage portion which may include a power storage device such as a battery, a super- capacitor, and/or the like. The switch portion may be actively controlled to store or release energy as desired by the RF portion 1 20, the controller 1 1 0, etc.

In accordance with embodiments of the present system, the RF portion 1 20 may further include a power storage state (e.g., a mode) during which one or more coils of the RF portion 1 20 may store induced power. In accordance with embodiments of the present system, the RF portion 1 20 may further include data storage states as will be described elsewhere. In accordance with embodiments of the present system, the timing of when the RF portion 1 20 enters the states (e.g., tune, detune, data storage, etc.) may be controlled by timing information provided by the RF clock. Though the RF portion 1 20 is illustratively shown located within the main bore 1 1 2 and the body 1 02, in accordance with embodiments of the present system, the RF portion 1 20 may be located outside of one or more of the main bore 1 1 2 and the body 102 (e.g., the RF portion 120 may be located outside of the main bore 1 1 2 within the body 1 02, the RF portion 1 20 may be located outside of the main bore 1 1 2 and the body 102, etc.) .

Methods to wirelessly synchronize the RF clock in accordance with embodiments of the present system are discussed further herein. In accordance with embodiments of the present system, RF clock synchronization may be accomplished, for example, by using a phase-locked-loop (PLL) circuit or a Costas loop circuit. PLL clock synchronization

With regard to the PLL clock synchronization system, FIG. 2 shows a schematic block diagram of an exemplary portion of a PLL clock synchronizer 200 using a pilot carrier input as a wireless synchronization signal in accordance with embodiments of the present system. The wireless synchronization signal may include a carrier signal such as a pilot tone that is wirelessly transmitted (e.g., from a transmitter 130 of the controller 1 1 0) to and received by the RF portion (e.g., received by a receiver 132 of the RF portion 1 20) . In accordance with some embodiments, the received signal may be received by one or more receive coil(s) or one or more antennas of the RF portion. For example, in accordance with embodiments of the present system, receive coils of the RF portion may be tuned and/or matched to two frequencies: such as an MRI signal frequency and a clock synchronization frequency. Once the single pilot carrier input signal (e.g., the detected signal) is received, it may be processed such as amplified, filtered, etc. for use to synchronize a Phase-Locked-Loop (PLL) circuit, such as the PLL circuit 228. In accordance with embodiments of the present system, the detected signal may be passed on to a PLL circuit that may act as a bandpass filter and may remove jitter from the detected signal. In accordance with embodiments of the present system, the PLL circuit 228 may thereafter output or otherwise provide a corresponding recovered clock output signal.

In accordance with embodiments of the present system, the pilot carrier input may be defined as V · sin(<»_p · t + Φ_ρ (t)) , the recovered clock output signal may be defined as V_r - s {N · ω_ρ ·ί + Φ_Γ(ί)) , where V_P is an amplitude of the pilot carrier input signal, ω_Ρ is an angular frequency of the pilot carrier input signal (e.g., in radians/second),† is time (sec), N is an integer that may be used as a multiplier/divider as will be discussed below, , Φ (Ι) is phase noise of the pilot carrier input signal, V_r is an amplitude of the recovered clock output signal, and O_r(t) is phase noise of the recovered clock output signal. The phase noise O_r(t) of the recovered clock output signal may be defined as a combination of phase noise Φ (Ι) of the received single pilot carrier input signal and the phase noise generated by the PLL circuit 228. Accordingly, the PLL 228 in accordance with embodiments of the present system is configured to minimize phase noise of the recovered clock output signal. With regard to the integer N, an oscillator internal to the PLL circuit 228 may be set to run at an integer multiple (e.g., N) of an incoming clock signal to produce an internal clock signal. This internal clock signal may then be divided by N (so that it may have a desired frequency that may be equal to a frequency of the detected signal (e.g., an incoming clock signal)) so as to form a generated clock signal before being passed on to the phase comparator that compares the generated clock signal with the detected signal and outputs the recovered clock output signal. This may be beneficial for phase lock which may be achieved for signals with identical frequency.

It is further envisioned that in accordance with some embodiments, the incoming clock signal may be utilized for energy harvesting. Accordingly, circuitry for utilizing energy harvesting methods may be provided in accordance with embodiments of the present system. Costas Loop-type clock synchronization

With regard to a Costas loop-type clock synchronization system, FIG. 3 shows a schematic block diagram 300 of an exemplary portion of a Costas loop-type clock synchronizer using a pilot carrier input in accordance with embodiments of the present system.

The Costas loop-type synchronizer in accordance with embodiments of the present system may include a Costas loop 334 which is a type of PLL circuit that may be used for carrier phase and frequency recovery for example from suppressed-carrier (SC) modulation signals, such as from dual-sideband suppressed carrier (DSB-SC) signals generated in accordance with embodiments of the present system. For example, the Costa loop 334 may receive a modulated signal (MSr) as a pilot carrier input. In accordance with embodiments of the present system, the Costas loop 334 may recover carrier and pilot signals (CSr) and (PSr) respectively from the received modulated signal (MSr) . More particularly, the Costas loop 334 may form two signals: a quadrature signal Q(t) and an in-phase signal l(t), the latter of which is the recovered pilot signal (PSr) . Then, the recovered pilot signal (PSr) may be provided to a mixer 344 and an RF clock synchronizer 348. In accordance with embodiments of the present system, the RF clock synchronizer 348 may synchronize a clock of the RF portion to the system clock. The mixer 344 may for example, multiply the in-phase signal l (t) by the quadrature signal Q(t) and provide the product to a loop filter 346 which is a low-pass filter for filtering higher order modulation terms. For example, if the signals l(t) and Q(t) are single tone sinusoidal signals, than in accordance with embodiments of the present system, the loop filter 346 may be a filter that has a cut-off frequency that is well below a frequency range of either of the signals l (t) and Q(t) so as to essentially pass a direct current (DC) component of the product of the signals l(t) and Q(t). This filtered product may form a loop error signal (LES) which may be used for example†o control frequency and phase of a numerically controlled oscillator (NCO) 352 which outputs a recovered carrier signal (CSr) having a recovered carrier frequency (f_rc) . More particularly, if the loop error signal (LES) is a negative value, the NCO decreases the recovered carrier frequency (frc) and if the loop error signal (LES) is a positive value, the NCO increases the recovered carrier frequency (frc) . In accordance with embodiments of the present system, a PLL circuit may be set up so that an increase in the LES results in an increase in the NCO frequency and vice versa.

An advantage of Costas loop-based synchronization methods over PLL synchronization methods (such as that shown in FIG. 2) is that at small deviations of phase, the Costas loop error voltage is sin(2(9i-9f)) as opposed to an error voltage of sin (Bi-Bf) for PLL synchronization methods. This translates to double the sensitivity and also makes the Costas loop based synchronization system better suited for tracking signals such as doppler-shifted carriers. An additional advantage of the Costas Loop based clock recovery is the potentially higher SNR of the incoming signal. This is due to the fact that the incoming signal can be an entire band of spectrum and thus contain higher energy.

Dual Sideband Suppressed Carrier (DSB-SC) Arbitrary signal generation

A method to generate gn grbitrary DSB-SC signgl will now be discussed with reference to FIG. 4, which shows o schemgtic block diogram 400 of o portion of an exemplary synchronizer 41 1 in accordance with embodiments of the present system. The synchronizer 41 1 is similar†o the synchronizer 1 1 1 and may include a mixer 415 for mixing (e.g., multiplying) a pilot signal (PS) (e.g., a pilot tone or message signal) and a (frequency) carrier signal (CS) to obtain for example a product which is a modulated signal (MS), for example, as may be defined by Equation 1 below in accordance with embodiments of the present system. The pilot signal (PS) may include desired information such as one or more pilot tones that for example may be selected by the system in accordance embodiments of the present system. For example, the pilot signal (PS) may include desired information such as pilot tones which may be selected by the system in accordance with a desired operation state (e.g., operating mode) for the RF portion (e.g., 120).

V^' _m cos ( _mi) x V_ccos (<¾;*) COS -I- 0½) t) -I- COS {{¾ - iVn) t) ...Eq. (i ;

Audio Carrier USB LSB

Mixer

where V_m is an amplitude of the pilot signal (e.g., PS), co_m is an angular frequency of the pilot signal (PS) (e.g., in radians/second),† is time (sec), V_c is an amplitude of the carrier signal (e.g., CS), co_c is an angular frequency of the carrier signal (CS) (e.g., in radians/second), USB refers to an upper-side-band and LSB refers to a lower-side-band of the modulated signal

FIG. 5 shows a graph 500 of a spectrum plot of a DSB-SC signal generated in accordance with embodiments of the present system. The DSB-SC signal may lack a carrier as indicated by the dotted oval 503 and may essentially be considered an amplitude modulation (AM) signal without a carrier. Further, in graph 500, fc denotes a carrier frequency (e.g., a frequency of a carrier signal (CS) and fp denotes pilot frequency (e.g., a frequency of the pilot signal (PS)) .

Dual Sideband Suppressed Carrier (DSB-SC) Pilot Tone DSB-SC signal generation

A method to generate a single pilot tone ond a DSB-SC signgl will now be discussed with reference to FIG. 6 which shows o schemgtic block diogram of a portion of a synchronizer 620 including a mixer 61 5 for mixing a single pilot signal (PS) and a carrier signal (CS) to form a modulated signal (MS) in accordance with embodiments of the present system. The single pilot signal (PS) , the carrier signal (CS) , and the modulated signal (MS) (e.g., the output signal) may be represented by Equations 2 through 4, respectively, as illustrated below. Further, a bandpass filter 608 may be provided to pass portions of the modulated signal (MS) which are located within one or more desired bands such as signals located within an envelope defined by the dotted lines 707 (as will be described below with reference to FIG. 7) and filter signals outside of the pass band (e.g., outside of the dotted lines) . The filtered modulated signal (MS) may then be provided to a transmission antenna (or antennas (for diversity, if desired) and/or resonators) 628 for transmission to an RF portion such as the RF portion 1 20. V_p - sm( o_p - t) , ...Equation (2)

Pilot signal (PS) =

V_c - sin(<»_c - t), and ...Equation (3)

Carrier signal (CS) =

— - [cos((ft>_c + ft>_p )- i)+ cos((ft>_c - ω_ρ )- t)], ... Equation (4)

Modulated signal (MS) =

where† is time (sec) , V_P is an amplitude (volts) of the pilot signal (PS) , ω_Ρ is an angular frequency of the pilot signal (PS) (rad/sec) , V_c is an amplitude of the carrier signal (CS) with an angular frequency coc, wherein the V_P and the V_c are assumed to be

substantially sinusoidal signals . In accordance with embodiments of the present system, it is envisioned that a pilot signal may also include a group of frequencies formed by a plurality of signals where each signal of the plurality of signals may include its own phase and amplitude modulation. Further, this group of signals may then be used for energy harvesting and may enhance the SNR of an incoming DSB-SC signal.

The output of the synchronizer 620 may be represented as shown in FIG. 7 which shows a graph 700 of an output spectrum of the modulated signal (MS) in accordance with embodiments of the present system. The graph 700 shows that the output spectrum of the modulated signal (MS) is centered about co_c with sidebands located at coctcop. However, as the signal is a DSB-SC signal, there is no significant signal present at Qc (e.g., carrier signal) as illustrated by the dotted lines 705. The bandpass filter may be provided to pass signals within one or more desired bands such as signals located within an envelope defined by the dotted lines and filter signals outside of the dotted lines.

Dual Sideband Suppressed Carrier: DSB-SC Pilot Tone Transport via Channel After the pilot signal (PS) is generated by, for example, a synchronizer, it may be processed such as by mixing the pilot signal (PS) with a carrier signal (CS) (as illustrated in FIG. 4) to form a modulated signal (MS) . The modulated signal (MS) may then be transmitted via any suitable wireless channel to a receiver such as a receiver of an RF coil operating in accordance with embodiments of the present system.

FIG. 8 which shows a schematic block diagram 800 of transmission and reception of a DSB-SC synchronization signal, such as a modulated signal (MS), over a wireless channel 813 in accordance with embodiments of the present system. More, particularly, a synchronizer 81 1 forms a modulated signal (MS) which is a DSB-SC signal and includes a pilot signal (e.g., including a pilot tone or tones) that corresponds with a system clock and a carrier signal (CS) . Further, the pilot signal (PS) may further be formed in accordance with selected state (mode) information which may indicate for example an operating state (e.g., mode) which the RF portion may be configured to operate after the selected state information is received/identified. The modulated signal (MS) at transmission may be known as a transmitted modulated signal (MSt) and may generally be represented as shown in Equation 4 above.

However, as wireless channels can contribute to amplitude and phase errors which can negatively affect the integrity of the pilot signal, a recovered signal transmitted over these wireless channels may include signal errors. These errors may be considered a form of noise and may be modeled as random variables such as a random variation At in the signal arrival time and additive noise n(t) . After transmission (e.g., after the transmitted modulated signal (MS) is received by an antenna of an RF portion 820), the received modulated signal may be subject to noise and fading. For example, a received modulated signal based on the transmitted modulated signal (of Equation 5) may be known as a recovered modulated signal (MSr) and may be represented as shown in Equation 5 below. )

...Equation (5)

Both of the above- mentioned random variables (i.e., At and n(t) of Equation 5) may produce errors in phase and amplitude, respectively, of the recovered pilot signal (PS) . As embodiments of the present system may employ a pilot tone for clock recovery to synchronize an internal clock of the RF portion, a primary concern is phase noise of a recovered pilot tone obtained from the recovered pilot signal (PSr) . This recovery may be performed by a clock recovery portion of the RF portion.

As mentioned above, a pilot tone (e.g., a pilot signal) may be used for clock recovery under certain conditions such as if it is an integer fraction of the recovered carrier signal. However, in accordance with yet other embodiments of the present system, it is envisioned that a recovered carrier signal may be used for clock recovery.

FIG. 9 shows a schematic block diagram of a portion of an MR system 900 with a wireless-type RF portion 920 in accordance with embodiments of the present system. The MR system 900 may include a synchronizer 91 1 which may form a modulated signal (MS) which is a synchronization signal and includes a pilot signal (PS) mixed with a carrier signal (CS) . The synchronizer 91 1 may transmit the modulated signal (MS) via any suitable wireless method such by using an antenna 921 (or more than one antenna with diversity) of the synchronizer 91 1 as a transmitted modulated signal (MSt) . Then, the transmitted modulated signal (MSt) may be received by an antenna 932 of the RF portion 920 and will now be referred to as a recovered modulated signal (MSr) . The recovered modulated signal (MSr) may then for example be provided to a Costas loop- type PLL circuit 934 (CL) of a clock recovery portion (CRP) 930 of the RF portion 920 in accordance with embodiments of the present system. Then Costas loop 334 may process the recovered modulated signal (MSr) to recover carrier and pilot signals (CSr) and (PSr) respectively from the recovered modulated signal (MSr) .

More particularly, the recovered modulated signal (MSr) may be split and forwarded to first and second mixers 936 and 938, respectively and multiplied at these respective mixers with an in-phase signal (e.g., a recovered carrier signal (CSr) as will be described below) and a 90 degree phase-shifted recovered carrier signal (CS_r-9o) and the products may then be filtered at first and second filters 942 and 950, respectively, to remove high-frequencies.

A description of signal processing in the in-phase arm of the Costas loop 934 in accordance with embodiments of the present system will now be described. However, the signal processing of the quadrature arm is similar with a difference being a phase change.

For example, assuming the recovered modulated signal (MSr) is defined as shown in Equation 5 as: -^y^ · [cos((<»_c + ω_ρ )· (ί + At))+ cos((a>_c - ω_ρ )· (ί + At))+ n(t^ , and the recovered carrier signal (CSr) is defined as shown in Equation 6 below, ^■ί + Φ(ή), ...Equation (6) then, the first mixer 936 may output a product of these two signals (e.g., the signals of Equations 5 and 6) which may be considered to be an unfiltered recovered pilot signal (PSr) and may be defined as:

V c V p V r cos((i»_c + ω_ρ ) · (t + At)) · cos(i»_c · t + φ(ή)

+ cos((i»_c - ω_ρ ) · (t + At)) · cos(i»_c · t + φ(ί)) + n(t)^■ cos(i»_c · t + φ(ί))

...Equation (7)

1

Using the identity: cos(«)cos( ?) =— [cos(« + 0) + cos(« - ?)] , the product may be redefined as: v v v cos((»_c + ω_ρ (t + At)+ (m_c ^■ t + (ή))+ cos((m_c + ω_ρ (t + At)- (m_c ^■ t + φ(ή))

+ cos(( _c - a>_p )- (t + At) + (a>_c - t + (ί))) + cos((ffi»_c - ω_ρ )^■ (/ + At) - (co_c ^■ t + φ(/))) + n(/)^■ cos(ffi»_c ^■ t + φ(/)) and simplified to: v v v cos((2»_c + ω_ρ )^■ t + (co_c + ω_ρ )^■ At + Φ(/))+ cos(ffl_p ^■ t + (co_c + ω_ρ )^■ At - φ(/))

+ cos((2»_c - co_p )^■ t + {co_c - co_p )^■ At + φ(/)) + cos(- co_p ^■ t + {co_c - co_p )^■ At - φ(/)) + n(/)^■ cos(c _c ^■ t

...Equation (8)

Thus, the signal of Equation 8 may form the unfiltered recovered pilot signal (PSr) . However, by passing this signal (e.g., the unfiltered recovered pilot signal (PSr) ) through the first filter 942, which is a low-pass filter having a transfer function H i(s), the higher frequency components of Equation 8 may be eliminated to form a recovered pilot signal (PSr) as defined in Equation 9 below.

[cos(ft>_p · (t + At) + (o_c ^■ At - φ(ή) + cos(- ω_ρ ^■ (t + At) + ω_ε ^■ At - φ(ή) + n_DM (t)] ...

Equation (9) Then, by simplifying Equation 9, the recovered pilot signal (PSr) may be defined as: n_DM {

... Equation ( 1 0)

Further, the recovered pilot signal (PSr) may include a recovered pilot tone or tones. For the sake of clarity and simplicity, it will be assumed that the term cos(co_P+A†- O(tj) approaches 1 for small values of At and O(t) .

With regard to a quadrature arm of the Costas loop, the second mixer 938 may mix the recovered modulated signal (MSr) with the 90 degree phase-shifted recovered carrier signal (CSr) which may be defined as V_r sin(<w_c · t + (t)) ) to obtain a product which may be an unfiltered quadrature signal Q(t), which may be similar to the

unfiltered pilot signal (PSr) with a different phase.

Then, by passing this signal (e.g., the unfiltered quadrature signal Q(†)) through the second filter 950, which is a low-pass filter having a transfer function HQ(S), the higher frequency components of the unfiltered quadrature signal Q(t) may be eliminated to form a recovered quadrature signal Q(t) similarly to the operation of the first filter 942.

Loop Control Signal

A loop control signal may be operative as control signal to control a voltage control oscillator (VCO) such as a numerically controlled oscillator (NCO) 952 and may be formed using a filtered product of the recovered pilot signal (PSr) (as shown in Equation 10) and the recovered quadrature signal Q(t). Accordingly, the recovered quadrature signal Q(t) and the recovered pilot signal (PSr) may first be multiplied by a third mixer 944 and the product (as output by the third mixer 944) may be defined as:

V cV p 'V r cos((i»_c + ω_ρ )^■ (t + At))- sin(i»_c · t + φ(ή)

+ cos((i»_c - ω )^■ (t + At)) · sin(i»_c · t + φ(ή) + n(t)^■ sm^' (a>_c ^■ t + φ(ή)

...Equation (1

1

Using the identity: sin(«:)cos(?) =— [sin(« + 0) + sin(« - ?)] , the product of Equation 11 may be redefined as: vvv sin(iy_c ^■ / + At))

+ sin(iy_c -ί

+ At)) +n(t)-sm(a)_c t + Φ and simplified to:

V cV pV r sin((2<y_c +

t + Φ(ή+ [co_c +a>_p)-At)+smfo(t)-a>_p -(t + At))

+ sin((2iy_c -ω_ρ)+φ(ί)+{ω_ΰ -<y_p)-At)+sin(©(t) + <y_p · (t + At))+ n(t)- s (o_c - ί + Φ'

...Equation (12)

The signal of Equation 12 may form an unfiltered loop control signal. However, by passing this signal (e.g., the unfiltered loop control single) through third filter 946, which is a low-pass filter having a transfer function F(s), the higher frequency components of Equation 12 may be eliminated to form a loop control signal as defined in Equation 13 below.

^VcVpVr .[sin(p(f) + fi> -(r + At))+sin(D(r)-fi> -{t + At ))+n_DMC(t)]... Equation (13)

Then, by simplifying Equation 13, the loop control signal may be defined as:

The NCO 952 may receive the loop control signal as an input and may output a signal which is the recovered carrier signal (CSr) in accordance with a voltage of the loop control signal. With regard to the loop control signal, if it is positive, the NCO 952 may decrease a frequency of the recovered carrier signal (CSr) and if it is negative, the NCO 952 may increase a frequency of the recovered carrier signal (CSr) . Thus, in accordance with embodiments of the present system, a loop control signal may act to move NCO towards a correct frequency and, thus, act to reduce a loop control signal.

The recovered carrier signal (CSr) may then be provided to the first mixer 936 for mixing with the recovered modulated signal (MSr) as discussed herein and to a phase shifter 940 for phase shifting by a desired amount such as 90 degrees. The phase shifter 940 may then provide its output to the second mixer 938 for mixing with the recovered modulated signal (MSr) as discussed herein.

Both, the phase noise of the recovered carrier signal and the phase noise of the recovered pilot signal may be partially due to noise picked up during channel propagation such as over the wireless channel. This noise may be described via a channel signal-to-noise ratio (SNR) . For example, if it is desired to improve the channel SNR, the system may increase the power of the modulated signal for transmission. This may be done where channel noise cannot be decreased. However, there are limitations to the maximum signal amplitude of the modulated signal due to saturation and/or non-linearity of the components involved in increasing the amplitude of the modulated signal such as amplifiers, etc. However, to overcome this limitation, embodiments of the present system may increase signal energy of the modulated signal (MS) in frequency space. For example, this may be accomplished by adding multiple pilot tones with different frequencies and/or amplitudes to the carrier signal (CS) prior to modulation of the pilot signal with the carrier signal (as may be performed by the synchronizer 91 1 so as to form a pilot signal. One or more of the multiple pilot tones may be indicative of a desired operating mode, a desired function, etc., as may be set by the user and/or system and which may stored in a memory of the system (e.g., in any suitable format) for later use. Further, embodiments of the present system may further act to enhance suppression of unwanted coherent distortions such as spikes and the like.

Further, the synchronizer may communicate with the RF portion by modulating the pilot signal (PS) with information. This may be accomplished using any suitable modulation method such as Binary Phase Shift Keying (BPSK), Multiple Frequency Shift Keying (MFSK), combinations thereof, etc. which may be performed by the synchronizer 91 1 . This information may include clock synchronization information, RF portion operating state information (e.g., tune, detune, and power storage modes, etc.), etc. The pilot tones of the pilot signal (PS) may be included in an enhanced pilot tone spectrum.

FIG. 10 shows an enhanced pilot tone spectrum 1000 of a recovered pilot signal

(PSr) in accordance with embodiments of the present system. The RF clock synchronizer 948 may analyze a recovered pilot signal (PSr) for one or more pilot tones included therein. Then, upon detecting the presence of a particular pilot tone or tones in the recovered pilot signal (PSr), the corresponding state may be identified and the RF portion 920 may be controlled accordingly to enter the corresponding state such as a tune, detune, synchronize (e.g., a clock synchronization), digitized information transfer, and/or power storage states. In accordance with embodiments of the present sytem, it is desirable that no significant carrier (or other frequency) components are located at Qc as illustrated by the dotted line 1005. Further, several pilot tones PT-1 through PT-3 (generally PT-x) are present centered in sidebands about co_c ± ω_Ρ and may be filtered using a bandpass filter tuned to the pass desired frequencies or a range of frequencies within the dotted lines 1007 so as to pass desired pilot tones centered at about co_c ± ω_Ρ such as the PT-xs. The PTs in these sidebands (e.g., upper and lower sidebands PT2 and PT3, respectively) may represent information encoded by the synchronizer 91 1 into the pilot signal (PS) prior to mixing (e.g., with a carrier signal (CS)) and transmission.

For example, FIGs. 1 1 A through 1 1 D each illustrate an enhanced spectrum in accordance with embodiments of the present system. More particularly, FIG. 1 1 A shows a graph 1 100A of an enhanced spectrum for entering a first RF operating state in accordance with embodiments of the present system; FIG. 1 1 B shows a graph 1 100B of an enhanced spectrum for entering a second RF operating state in accordance with embodiments of the present system; FIG. 1 1 C shows a graph 1 100C of an enhanced spectrum for entering a third RF operating state in accordance with embodiments of the present system; and FIG. 1 1 D shows a graph 1 100D of an enhanced spectrum for entering a fourth RF operating state in accordance with embodiments of the present system. In accordance with embodiments of the present system, although the states may be defined using numerical conventions, they do not have to follow any particular order. Further, the controller 1 10 may, in some embodiments, select an operating state based upon, for example, timing of an MR pulse sequence to be output by the MR system (e.g., by the gradient coils, the RF coils, etc.) during a scan. In accordance with embodiments of the present system, the RF portion may determine its operating states based upon its pulse output. With reference to graph 1 1 00A three pilot tones are shown; a center tone at ωο±ω_Ρ which will be referred to as tone A, a second tone at COc±{ CO p+ Δ) which will be referred to as tone B and is an upper sideband, and a third tone at ωο±(ωρ- Δ) which will be referred to as tone C and is a lower sideband. In accordance with embodiments of the present system, the controller 1 1 0 may select an operating state to place the RF portion based upon, for example, a timing sequence of a scan being performed. In accordance with embodiments of the present system, the controller 1 10 may use an operating state table (e.g., stored in a memory such as the memory 1320 shown in FIG. 1 3) to determine corresponding pilot tones to insert into pilot signal (PS) for transmission to the RF portion.

Upon recovering the pilot signal (PSr) , the RF clock synchronizer 948 may identify which recovered pilot†one(s) are present in the recovered pilot signal (PSr) . In accordance with embodiments of the present system, the RF clock synchronizer 948 may determine a corresponding state based upon the identified recovered pilot †one(s) and control the RF portion accordingly. As discussed herein, the operating states may be set by the user and/or system. For example, Table 1 shows an operating state table in accordance with embodiments of the present system.

Table 1

The operating state table may be set by the user and/or system and may be stored in a memory of the system. Thereafter upon detecting pilot tones in a recovered pilot signal (PSr), the RF clock synchronizer 948 may compare the detected pilot tones with those stored in the memory (e.g., Table 1 ) and determine a corresponding operating state for the RF coil. Then, the RF portion 920 may be controlled to enter or otherwise enter an operating state/mode in accordance with the determined corresponding operating state. In accordance with embodiments or the present system, the detected pilot tones may be compared with threshold values for each of the pilot tones (e.g., threshold values for each of absolute values for coc-ω _P, ωο±(ω_Ρ+ Δ _Ρ) , and coc±(cop- A p) ) . Then, if a detected pilot tone of the pilot tones is substantially equal to a threshold pilot tone value, the system may select a corresponding operating state/mode. However, if the detected pilot tone is not substantially equal to the threshold pilot tone value, the system may not select an operating state/mode which corresponds with the threshold pilot tone value.

Thus, assuming the system detects the pilot tones shown in graph 1 100B of FIG. 1 1 B (e.g., pilot tones A and B only and not C), then with reference to Table 1 , the system may determine to enter a tune mode (state) . For example, the synchronizer 91 1 may perform a reverse lookup using Table 1 that may be stored in substantial form in a memory. For example, if it is determined that the RF portion should enter a detune state, the synchronizer 91 1 may modulate the pilot signal to include pilot tones A and C. Thereafter, upon recovering the corresponding pilot signal, the RF portion may analyze a recovered pilot signal and thereafter determine to enter the detune state.

Further, the RF clock synchronizer 948 may compare a detected amplitude of one or more of the pilot tones with a corresponding threshold value which may be a general threshold value or may correspond with a threshold amplitude value for a corresponding pilot tone. Then, if it is determined that the amplitude of a detected pilot tone is greater than or equal to the corresponding threshold value, the RF synchronizer 948 may set a corresponding state (e.g., as set forth in the operating state table). However, if it is determined that determined that the pilot tone is less than the corresponding threshold value, the RF synchronizer 948 may ignore the pilot tones.

Dual Sideband Suppressed Carrier-Center DSB-SC signal on MRI frequency

A method of transmitting a Dual Sideband Suppressed Carrier and Center DSB-

SC signal on an MRI frequency is discussed herein with reference to FIG. 1 2 which shows a graph 1200 of a combined spectrum including a Center DSB-SC signal and an MRI signal in accordance with embodiments of the present system. The Center DSB-SC signal may be a modulated signal (MS) which includes a pilot signal (PS) mixed with a carrier signal (CS) and may be centered on the MRI frequency without interfering with the MRI signal (and vice versa) provided that frequency components of the DSB-SC signal are maintained above or below a spectrum of the MRI spectrum as shown in the graph 1200. Thus, for example, pass-bands 1 207 of a band pass filter (BPF) should lie outside of a spectrum of the MRI signal as shown which may be defined as a signal centered at co_c and having a bandwidth of ±COBW about co_c. An anti-aliasing filter may be provided to limit signal bandwidth so as to avoid aliasing of noise.

FIG. 13 shows a portion of a system 1 300 (e.g., peer, server, etc.) in accordance with embodiments of the present system. For example, a portion of the present system may include a processor 1 31 0 (e.g., a controller) operationally coupled to a memory 1 320, a display 1 330, RF transducers 1 360 (e.g., such as coupled through a wireless coupling), magnetic coils 1 390, and a user input device 1 370. The memory 1 320 may be any type of device for storing application data as well as other data related to the described operation. The application data and other data are received by the processor 1 31 0 for configuring (e.g., programming) the processor 1 31 0 to perform operation acts in accordance with the present system. The processor 131 0 so configured becomes a special purpose machine particularly suited for performing in accordance with embodiments of the present system.

The operation acts may include configuring an MRI system by, for example, controlling optional support actuators, the magnetic coils 1 390, and/or the RF transducers 1 360. The support actuators may control a physical location (e.g., in x, y, and z axes) of a patient, if desired. The magnetic coils 1 390 may include main magnetic coils, and gradient coils (e.g., x-, y-, and z-gradient coils) and may be controlled to emit a main magnetic field and/or gradient fields in a desired direction and/or strength. The controller may control one or more power supplies to provide power to the magnetic coils 1390 so that a desired magnetic field is emitted at a desired time. The RF transducers 1360 may be controlled to transmit RF pulses at the patient and/or to receive echo information therefrom. A reconstructor may process received signals such as the echo information and transform them (e.g., using one or more reconstruction techniques of embodiments of the present system) into content which may include image information (e.g., still or video images (e.g., video information)), data, and/or graphs that can be rendered on, for example, a user interface (Ul) of the present system such as on the display 1 330. Further, the content may then be stored in a memory of the system such as the memory 1 320 for later use. Thus, operation acts may include transmitting and/or receiving a synchronization signal, requesting, providing, and/or rendering of content such as, for example, reconstructed image information obtained from the echo information, etc. The processor 1 31 0 may render the content such as video information on a Ul of the system such as a display of the system. As may be readily appreciated, the RF transducers may further include a processor, such as the processor 1 310.

The user input 1 370 may include a keyboard, a mouse, a trackball, or other device, such as a touch-sensitive display, which may be stand alone or be a part of a system, such as part of a personal computer, a personal digital assistant (PDA) , a mobile phone (e.g., a smart phone), a monitor, a smart- or dumb-terminal or other device for communicating with the processor 1 31 0 via any operable link. The user input device 1 370 may be operable for interacting with the processor 1 31 0 including enabling interaction within a Ul as described herein. Clearly the processor 1 310, the memory 1 320, display 1 330, and/or user input device 1 370 may all or partly be a portion of a computer system, MRI device, etc., such as a client and/or server.

The methods of the present system are particularly suited to be carried out by a computer software program, such program containing modules corresponding to one or more of the individual steps or acts described and/or envisioned by the present system. Such program may of course be embodied in a computer-readable medium, such as an integrated chip, a peripheral device or memory, such as the memory 1 320 or other memory coupled to the processor 1 31 0.

The program and/or program portions contained in the memory 1 320 may configure the processor 1 31 0 to implement the methods, operational acts, and functions disclosed herein. The memories may be distributed, for example between the controller 1 10 and the RF portion 120, or local, and the processor 1 31 0, where additional processors may be provided, may also be distributed or may be singular. The memories may be implemented as electrical, magnetic or optical memory, or any combination of these or other types of storage devices. Moreover, the term "memory" should be construed broadly enough to encompass any information able to be read from or written to an address in an addressable space accessible by the processor 1 31 0. With this definition, information accessible through a network 1 380 is still within the memory, for instance, because the processor 131 0 may retrieve the information from the network for operation in accordance with the present system.

The processor 1 31 0 is operable for providing control signals and/or performing operations in response to input signals from the user input device 1 370 as well as in response to other devices of a network and executing instructions stored in the memory 1 320. The processor 1 31 0 may include one or more of a microprocessor, an application-specific or general-use integrated circuit(s) , a logic device, etc. Further, the processor 131 0 may be a dedicated processor for performing in accordance with the present system or may be a general-purpose processor wherein only one of many functions operates for performing in accordance with the present system. The processor 131 0 may operate utilizing a program portion, multiple program segments, or may be a hardware device utilizing a dedicated or multi-purpose integrated circuit.

Digital Costas loop circuits in accordance with embodiments of the present system are illustratively described with reference to FIGs. 1 4 and 1 5.

FIG. 1 4 shows a schematic block diagram of a portion of a portion of digital Costas loop clock synchronizer 1 400 (hereinafter the synchronizer) in accordance with embodiments of the present system. The synchronizer may receive a DSB-SC signal and may include one or more of an anti-aliasing signal 1 402, an analog-to-digital sampling clock (ADC) 1 404, mixers 1406, 1 408, and 1 41 6, a numerically-controlled oscillator (NCO) 1 412, finite impulse response (FIR) filters 1 41 0, 141 4, and 1 41 8, a digital-to-analog converter (DAC) 1 420 and a voltage-controlled oscillator (VCO) 1 422. The VCO 1 422 may control both the ADC sampling clock 1404 for receiving the filtered DSC-SC signal and a clock signal (Clock) for the NCO 1 41 2. However, from a digital frame of reference it appears as if the input DSB-SC signal changes in phase/frequency while the NCO generated signals sin (art) and cos (art) (which are output to the mixers 1 406 and 1 408, respectively) are fixed.

FIG. 1 5 shows a schematic block diagram of a portion of a portion of digital Costas loop-type clock synchronizer 1 500 (hereinafter the synchronizer) in accordance with embodiments of the present system. The synchronizer 1 500 may include one or more of an anti-aliasing signal 1 502, an analog-to-digital sampling clock (ADC) 1 504, mixers 1 506, 1 508, and 1 51 6, a numerically-controlled oscillator (NCO) 1 512, finite impulse response (FIR) filters 1 51 0, 1 51 4, and 1 518, a digital-to-analog converter (DAC) 1 520 and a free-running crystal oscillator (FR-CO) 1522. The FR-CO provides a clock signal (Clock) to the ADC 1504 which receives an incoming DSB-SC signal and to the NCO 1 512.

Analog Costas loop circuits using off-the-shelf components in accordance with embodiments of the present system may also be suitably utilized in accordance with embodiments of the present system.

Embodiments of the present system may provide wireless synchronization systems and methods for wireless-type RF coils. Suitable applications may include imaging systems such as MRI and MRS systems and the like which require: a short acquisition time and high resolution. Further variations of the present system would readily occur to a person of ordinary skill in the art and are encompassed by the following claims. Finally, the above-discussion is intended to be merely illustrative of the present system and should not be construed as limiting the appended claims to any particular embodiment or group of embodiments. Thus, while the present system has been described with reference to exemplary embodiments, it should also be appreciated that numerous modifications and alternative embodiments may be devised by those having ordinary skill in the art without departing from the broader and intended spirit and scope of the present system as set forth in the claims that follow. In addition, the section headings included herein are intended to facilitate a review but are not intended to limit the scope of the present system. Accordingly, the specification and drawings are to be regarded in an illustrative manner and are not intended to limit the scope of the appended claims.

In interpreting the appended claims, it should be understood that:

a) the word "comprising" does not exclude the presence of other elements or acts than those listed in a given claim;

b) the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements;

c) any reference signs in the claims do not limit their scope;

d) several "elements" may be represented by the same item or hardware or software implemented structure or function;

e) any of the disclosed elements may be comprised of hardware portions

(e.g., including discrete and integrated electronic circuitry), software portions (e.g., computer programming), and any combination thereof; f) hardware portions may be comprised of one or both of analog and digital portions;

g) any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise;

h) no specific sequence of acts or steps is intended to be required unless specifically indicated; and

i) the term "plurality of" an element includes two or more of the claimed element, and does not imply any particular range of number of elements; that is, a plurality of elements may be as few as two elements, and may include an immeasurable number of elements.

Claims

1 . A magnetic resonance (MR) system (100, 900, 1 300) having a system clock, the system comprising:

at least one controller ( 1 1 0, 1 31 0) which:

forms pilot and carrier signals, the pilot signal formed in accordance with at least the system clock, and

wirelessly transmits a dual sideband suppressed carrier (DSB-SC) signal based upon a product of the pilot and carrier signals; and

a wireless-type radio-frequency (RF) coil portion (1 20, 820, 920, 1 360) which: receives the DSB-SC signal,

recovers the pilot and carrier signals from the received DSB-SC signal, and sets a clock of the RF portion in accordance with the recovered pilot signal.

2. The MRI system of claim 1 , wherein the at least one controller further determines an operating state to set for the wireless-type RF coil portion.

3. The MRI system of claim 2, wherein the at least one controller further modulates the pilot signal in accordance with the determined operating state.

4. The MRI system of claim 3, wherein the at least one controller further modulates the pilot signal using at least one of a Binary Phase Shift Keying (BPSK) method and Multiple Frequency Shift Keying (MFSK) method.

5. The MRI system of claim 1 , wherein the wireless-type RF coil portion further identifies at least one recovered pilot tone from the recovered pilot signal.

6. The MRI system of claim 4, wherein the wireless-type RF coil portion determines an operating state of the wireless-type RF coil portion in accordance with the identified at least one recovered pilot tone from the recovered pilot signal.

7. The MRI system of claim 1 , wherein the MRI system further comprises a memory (1 320), and wherein the wireless-type RF coil portion:

acquires echo information;

forms digitized information comprising the acquired echo information and at least a synchronous portion of the received DSB-SC signal; and stores the digitized information in the memory.

8. The MRI system of claim 7, wherein the at least one controller further: obtains the digitized information from the memory;

extracts a clock synchronization signal from the digitized information; and reconstructs the digitized information in accordance with the extracted clock synchronization signal.

9. A wireless synchronization method for a magnetic resonance (MR) system (1 00, 900, 1 300) having a system clock and a wireless-type radio-frequency (RF) coil portion (120, 820, 920, 1 360), the method performed by at least one controller (1 1 0, 1 31 0) of the MR imaging system (1 00, 900, 1 300) and comprising acts of:

forming pilot and carrier signals, the pilot signal formed in accordance with at least the system clock;

wirelessly transmitting a dual sideband suppressed carrier (DSB-SC) signal which is based upon a product of the pilot and carrier signals; receiving, by the wireless-type RF coil portion, the DSB-SC signal;

recovering, by the wireless-type RF coil portion, the pilot and carrier signals from the received DSB-SC signal, and

setting, by the wireless-type RF coil portion, a clock of the wireless-type RF coil portion in accordance with the recovered pilot signal.

10. The method of claim 9, further comprising an act of determining an operating state to set for the wireless-type RF coil portion.

1 1 . The method of claiml 0, further comprising an act of modulating the pilot signal in accordance with the determined operating state.

12. The method of claim 1 1 , further comprising an act of modulating the pilot signal using at least one of a Binary Phase Shift Keying (BPSK) method and Multiple Frequency Shift Keying (MFSK) method.

13. The method of claim 9, further comprising an act identifying, by the wireless-type RF coil portion, at least one recovered pilot tone from the recovered pilot signal.

14. The method of claim 13, further comprising an act of determining an operating state of the wireless-type RF coil portion in accordance with the identified at least one recovered pilot tone from the recovered pilot signal.

15. The method of claim 9, further comprising acts of:

acquiring, by the wireless-type RF coil portion, echo information;

forming digitized information comprising the acquired echo information and at least a synchronous portion of the received DSB-SC signal; and storing the digitized information in a memory ( 1 320) .

1 6. The method of claim 1 5, further comprising acts of: obtaining, by the at least one controller, the digitized information from the memory; extracting a clock synchronization signal from the digitized information; and reconstructing the digitized information in accordance with the extracted clock synchronization signal.

1 7. A computer readable non-transitory memory medium (1 320) including instructions stored thereon, which, when executed by at least one controller, configures one or more of the at least one controller to perform a method of synchronizing a magnetic resonance (MR) system (1 00, 900, 1 300) having a system clock and a wireless-type radio-frequency (RF) coil portion ( 1 20, 820, 920, 1 360) , the method comprising acts of: forming pilot and carrier signals, the pilot signal formed in accordance with at least the system clock; wirelessly transmitting a dual sideband suppressed carrier (DSB-SC) signal which is based upon a product of the pilot and carrier signals; receiving, by the wireless-type RF coil portion, the DSB-SC signal; recovering, by the wireless-type RF coil portion, the pilot and carrier signals from the received DSB-SC signal, and setting, by the wireless-type RF coil portion, a clock of the wireless-type RF coil portion in accordance with the recovered pilot signal.

1 8. The computer program of claim 1 7, wherein the instructions configure one or more of the at least one controller to perform an act of determining an operating state to set for the wireless-type RF coil portion.

19. The computer program of claim 18, wherein the instructions configure one or more of the at least one controller to perform an act of modulating the pilot signal in accordance with the determined operating state.

20. The computer program of claim 19, wherein the instructions configure one or more of the at least one controller to perform an act of identifying, by the wireless-type RF coil portion, at least one recovered pilot tone from the recovered pilot signal.