WO2012122462A2

WO2012122462A2 - Use of magnetic resonance techniques for molecular detection

Info

Publication number: WO2012122462A2
Application number: PCT/US2012/028455
Authority: WO
Inventors: Ching-Hua Tseng; Shyamal Somaroo; Grum Teklemariam
Original assignee: Thimbletech, Inc.
Priority date: 2011-03-09
Filing date: 2012-03-09
Publication date: 2012-09-13
Also published as: WO2012122462A3

Abstract

System and methods are provided to perform non-invasive, real-time, continuous or episodic molecular detection and quantification of molecular species in a sample or animal or human subject using magnetic resonance. Such systems and methods may be applied to identify and quantify molecular species found in the body, which may be useful for many aspects of medical care including without limitation prenatal diagnosis, detecting deep skin infections, performing cerebral spinal fluid assessment, measuring arterial blood gases, blood glucose, cardiac biomarkers, and creatinine flow rates. The non-invasive, quantification of such molecular species continuously in real time enables significantly more attractive methods of diagnosis, monitoring and therapy than existing methods and protocols.

Description

USE OF MAGNETIC RESONANCE TECHNIQUES FOR MOLECULAR

DETECTION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and takes the benefit of US Provisional Application Serial No. 61/450,809 filed on March 9, 2011, the contents of which are incorporated herein by reference.

AREA OF TECHNOLOGY

[0002] The present invention relates to systems and spectroscopic techniques to study molecules using magnetic resonance.

BACKGROUND

[0003] Magnetic resonance methods extract molecular information such as location, composition, and dynamics from the electromagnetically excited response of molecular nuclear magnetic moment systems placed in an external magnetic field.

[0004] Spectroscopic information can be obtained from molecular species from nuclear magnetic resonance (NMR) methods (see, e.g., Principles of nuclear magnetic resonance in one and two dimensions, Richard R. Ernst, Geoffrey Bodenhausen, Alexander Wokaun, Oxford University Press, London/New York. 1987).

[0005] NMR methods have been used in in vivo human metabolomic studies, (see, e.g., Human in vivo NMR spectroscopy in diagnostic medicine: clinical tool or research probe? PA Bottomley, GE Research and Development Center, Schenectady, NY 12301, Radiology, Vol 170, 1-15, 1989.) However, NMR methods suffer from lack of sensitivity.

A steady state behavior can be established in a dynamic system by applying a repetitive drive. A particular case, as shown by Carr (Steady-State Free Precession in Nuclear Magnetic Resonance, H. Y. Carr, Phys. Rev. 112, 1693-1701 (1958).), is the steady state free precession (SSFP) method used in nuclear magnetic resonance (NMR). A description of the basic technique is given by Scheffler (Principles and applications of balanced SSFP techniques, Klaus Scheffler, Stefan Lehnhardt, Eur Radiol (2003) 13:2409-2418.)· The SSFP approach is commonly used in imaging (Oppelt A, Graumann R, Barfub H, Fischer H, Hartl W, Schajor W. 1986. FISP— a new fast MRI sequence. Electromedica 54(1): 15-18.) and gives high signal-to-noise data acquisition and discrimination of signals based on relaxation parameters. The steady state dynamics that results depends on the natural frequency and relaxation of the spin. This fact allows a spectroscopic capability, that is, spins of different natural parameters to be discriminated. By appropriate choices of parameters, a large contrast between the signal emitted by on- and off- resonance spins can be achieved. In particular, it is sometimes desired to suppress the signal from water so that weaker signals may be observed. A further application of SSFP is the phase discrimination of oxygenated states of hemoglobin for fMRI (Frequency Stabilization Using Infinite Impulse Response Filtering for SSFP fMRI at 3T, Ming-Long Wu, Pei-Hsin Wu,Teng-Yi Huang,Yi-Yu Shih, Ming- Chung Chou, Hua-Shan Liu, Hsiao-Wen Chung, and Cheng- Yu Chen, Magnetic Resonance in Medicine 57:369-379 (2007) and Karla Miller, Stephen Smith, Peter Jezzard, John Pauly, High- Resolution FMRI at 1.5T Using Balanced SSFP, Magnetic Resonance in Medicine 58: 161-170 (2006).). The advantage of such steady state approaches is that the signal strength per unit time is much improved compared to conventional free induction decay experiments. SSFP techniques would potentially enhance the molecular signal from a sample compared to the normal form of NMR spectroscopy, while eliminating non-resonant background, reducing measurement time, and enabling real-time analysis.

[0006] NMR methods for metabolite detection that do not depend on an SSFP like approach include: WO 99/32897 (1999) NMR apparatus and method for no n- invasive in -vivo testing of a patient's body fluid glucose levels, Anderson, Marvin, H., Schleich, Thomas W., John Boban K., Schoolery, James N.; US 6,404,197 Bl (2002) Small scale NMR spectroscopic apparatus and method, Anderson, Marvin, H., Schleich, Thomas W., John Boban K., Schoolery, James N.; US 5,685,300 (1997) Noninvasive and in-vitro measurement of glucose and cholesterol by nuclear magnetic resonance spectroscopy, Kuenstner, J. Todd; US 4,875,486 (1989) Instrument and method for non-invasive in vivo testing for body fluid constituents, Rapoport, U., and Panosh, R.; US 5,072, 732 (1991) NMR instrument for testing for fluid constituents, Rapoport, U., and Panosh, R.

[0007] Further non-SSFP-like spectral editing techniques for detecting resonances near water include: Recovery of underwater resonances by magnetization transferred NMR spectroscopy (RECUR_NMR), Liu, M., Tang, H., Nicholson, J., Lindon, J. Journal of Magnetic Resonance 153, 133-137 (2001).; Uncovering hidden in-vivo resonances using editing based on localized TOCSY, Marjanska, M., Henry, P., Bolan, P., Vaughn, B., Seaquist, E., Gruetter, R., Ugurbil, K., Garwood, M., Magnetic Resonance in Medicine, 53(4): 783-789 (2005).

[0008] Increased signal to noise ratio performance in steady-state free precession (SSFP) nuclear magnetic resonance methods would enable higher spatiotemporal resolution for cardiac imaging or functional imaging for example.

[0009] Non-invasive detection of physiological conditions is an attractive option compared to existing invasive protocols that may require, for instance, painful and potentially dangerous withdrawal of bodily fluid, such as blood, amniotic fluid, or spinal fluid. Many current proposals for non-invasive detection are either not sensitive to low levels of target molecules or cannot be calibrated to provide an absolute concentration value. Even for instances where an in vitro sample is available, existing highly sensitive assays may require an undesirable delay. Several examples are discussed below.

[0010] Prenatal diagnostics through chorionic villus sampling (CVS), amniocentesis, cordocentesis are commonly performed to rapidly verify the presence of Down syndrome or other fetal chromosomal abnormalities (18, 13), Tay-Sachs, cystic fibrosis, etc. These prenatal tests can also used to detect in fetuses the presence of infectious disease such as toxoplasmosis, rubella, or cytomegalovirus in the fetus, so that it can be treated, and to perform a blood count and check for anemia or low platelet levels. Unfortunately, the value of these diagnostics is counterbalanced by the unacceptably high risk of fetal loss at a rate of about one in two hundred.

[0011] Current non-invasive diagnostics, such as the triple or quad marker blood test coupled with other tests, such as ultrasound Nuchal translucency, free beta, PAPPA screens have a detection rate of only about 90-95%, with a false positive rate of 2-5%. A need therefore exists for a better way to discern chromosomal characteristics of the fetus without breaching the amniotic sac, or otherwise endangering the fetus.

[0012] Bacterial or viral detection is another common concern for healthcare providers and consumers in general. In particular, bacterial infection of the deep skin, called cellulitis, involves a rapid and potentially life-threatening infection, which can result in an extreme medical emergency. Following infection, the disease may spread to the lymph nodes and bloodstream and/or involve necrotizing fasciitis. Possible causes include Group A streptococcus, Vibrio vulnificus, Clostridium perfringens, Bacteroides fragilis, and/or Methicillin-resistant Staphylococcus aureus (MRS A). Cellulitis is often difficult to diagnose definitively and rapidly because its symptoms may resemble deep vein thrombosis or a rash caused by stasis dermatitis. Definitive bacterial cultures usually require days, and some bacterial causes of human infection cannot be easily cultured either by biopsy, wound culture, or saline wash. The disease may progress significantly leading to loss of limb or death before the 24-48 hours required for cultures to become positive. Other indirect blood markers of infection may not yield a diagnosis until the patient has developed general sepsis. It can thus be difficult to determine the severity of the health danger from the observed rash. Although patients suspected of harboring significant bacterial infection are generally treated with broad spectrum antibiotics until cultures allow definitive identification of bacterial species and antibiotic sensitivity, some resistant infections are not well treated by standard antibiotic regimens, and use of broad spectrum antibiotics carries significant individual and public health risks. A method to rapidly identify bacterial populations in the deep skin, and preferably to discern the class or specific strain of pathogen involved would have great clinical benefit both for diagnosis and for selection of effective antibiotics from among the numerous classes in general use.

[0013] Lumbar punctures, also known as spinal taps, are often performed to withdraw cerebral spinal fluid (CSF) to help diagnose meningitis, subarachnoid hemorrhage, hydrocephalus, cancers, inflammation, Multiple Sclerosis, neurosyphillis , among others. Unfortunately, lumbar punctures create the risk of epidural infection, paralysis, and paraplegia. A method of identifying diagnostic molecules in CSF in situ without piercing the membrane protecting the central nervous system would reduce the risk of such complications.

[0014] Alzheimer's disease is clinically diagnosed based on the presence of characteristic neurological and neuropsychological features. Presently, no non-invasive or pre-mortem bio marker for Alzheimer's exists. Similarly, there are no known bio markers for Parkinson's disease. An in situ method of monitoring CSF would be useful for evaluating drug response to new treatments of diseases, such Alzheimer's and Parkinson's disease.

[0015] Arterial blood gas measurements help doctors assess pulmonary function in numerous respiratory and metabolic conditions including sepsis, respiratory failure, diabetic ketoacidosis and other acute and chronic metabolic conditions, and management of critically ill, ventilated patients in the neonatal and adult intensive care units (ICU). Generally, ABG values are obtained through arterial puncture blood draws. Repeated intermittent invasive arterial puncture is painful and carries risks including infection, arterial injury and anemia. In dehydrated, chronically ill, or pediatric patients, arterial punctures can be technically difficult to perform. In neonates, blood loss from frequent ABG sampling can necessitate transfusions and increase the risk of intravascular contamination. Low volume samplings are subject to errors, especially in blood electrolyte concentration measurements. In addition to the discomfort, health risks, and difficulty scheduled or episodic ABG sampling may miss rapid fluctuations in blood oxygenation, carbon dioxide, glucose or pH. Continuous ABG monitoring could increase patient safety. Although some transcutaneous devices to monitor carbon dioxide and oxygen levels have been developed, they require frequent site changes and recalibration of the probe, and can be contraindicated in hemo dynamically compromised patients because of changes in blood flow to the tissues. Other devices, such as a pulse oximeter offer continuous estimation of blood oxygen saturation but give no information about pH or PaC02.

[0016] Acute heart attacks and congestive heart failure (CHF) is the leading cause of hospitalization for persons over 65 years of age. Currently, blood is withdrawn from patients to assess the level of enzyme and other molecular markers of cardiac muscle damage, and to diagnose or stratify the patient's condition. These tests must be repeated frequently in the acute phases of illness to monitor changes in substance levels. Some of the same cardiac biomarkers may be elevated in skeletal muscle injury. Real time continuous time course data may aid in the differential diagnosis, but current known and proposed methods to monitor these biomarkers are episodic and entail a time delay for analysis. Providing real time quantitative determination of cardiac biomarkers such as troponin, creatine kinase (CK-MB), myoglobin, B-type Natriuretic Peptide (BNP), aspartate transaminase, or lactate dehydrogenase could aid in the diagnosis and treatment of acute myocardial infarction (MI), congestive heart failure (CHF), and other acute coronary syndromes (ACS).

[0017] Renal function is measured by the glomerular filtration rate, which in turn is approximated by the creatinine clearance or filtration rate. The ability to measure directly creatinine levels in serum and urine in real time would enable the early detection of renal failure. Currently, definitive evaluation of renal function generally involves collecting urine for 24 hours and measuring the serum creatinine concentration. Often, doctors require a faster diagnosis, particularly if renal therapy is required, so GFR is estimated from measured serum creatinine using via the Cockcroft-Gault equation, and refinements thereon. A technique for real time measurements of serum and urine creatinine concentration and urine flow could allow faster and more accurate assessment of renal function. A continuous method could allow continuous monitoring of renal function in acutely ill patients with hypotension, sepsis, shock, trauma or other causes of acute renal failure.

[0018] Diabetes, a condition resulting from the body's incapacity to regulate glucose, afflicts 150 million people worldwide with China, India and the US most affected. In the US alone, 21 million individuals suffer from this disease. It is expected that the number of diabetics will grow at an annual rate of 10% as the population ages and life expectancy increases. Alarmingly, incidence in children and young adults is also rising. Diabetics risk many short and long-term secondary complications, including blindness, amputation and nerve damage. The majority of these complications are directly related to the peak and average levels of blood sugar, and tight control of blood sugar has been shown to prevent their development. Proper disease management via frequent monitoring of blood glucose levels is thus paramount. Unfortunately, the current commonly used method of measuring blood glucose levels by means of an invasive fingertip blood draw does not facilitate patient compliance for several reasons. Although the long-term medical consequences are severe, patients cannot sense high blood sugar directly and so feel fine unless the levels become extremely high. Consequently, patients often put off the immediate pain, discomfort, and inconvenience of a finger prick test . Furthermore, the information obtained provides only a single snapshot in time and so may fails to detect periods of dangerous hypoglycemia (too little glucose) and hyperglycemia (too much glucose). Not surprisingly, less than 30% of patients consistently check their glucose levels one or more times a day, even though doctors recommend that for tight control to be optimal, patients should monitor and control their blood sugar levels seven times a day. Non-invasive, painless, convenient methods of monitoring blood glucose could significantly increase compliance, improve patient outcomes and decrease treatment costs. No non-invasive means of measuring blood glucose concentration currently exist or have been proposed that are accurate enough for optimal quantitative measurement of the glucose levels in diabetics.

[0019] In addition to cardiac biomarkers and ABG, other measures of blood, such a complete blood count (CBC), which measures a patient's Hgb (hemoglobin) concentration, number of WBC (white blood cells), Pit (platelet) and Hct (hematocrit) values, have conventionally required a blood draw. A CBC is performed via automated (flow cytometry) or manual (blood film) counting. A non-invasive means of obtaining information regarding blood analytes would be desirable, especially in pediatric cases, for many of the same reasons discussed above.

[0020] Other biomarkers of interest to measure non-invasively include lactate, neurophysiology markers, blood lipids, and triglycerides. A non-invasive, and thus routinely accessible, multiple parameter measurement of biomarkers such as lipids, triglycerides, and glucose could provide a valuable indicator of metabolic health. SUMMARY

[0021] Embodiments of the invention provide magnetic resonance techniques for materials studies, medical diagnostic and therapeutic purposes, and calibration techniques for the same.

[0022] Under one aspect, the presence of a target substance or substances in a subject using nuclear magnetic resonance is measured by the following steps: determining a target resonance or resonances, generating an electromagnetic field pattern comprising a repeated pattern; exposing a portion of said subject to said electromagnetic field pattern so as to drive the target system toward or in a steady state cycle, and to suppress the signal from water, other metabolites, or non-target resonances, and enhance the signal from the target resonance or resonances, and to cause fields to emanate from said target substance in said subject; detecting said emitted fields from said target substance; and analyzing said emitted fields.

[0023] Some embodiments include electromagnetic field patterns comprising at least one of: continuous, non-instantaneous pulses, soft pulses, or spin lock drives; adiabatic pulses, time varying, swept, frequency modulated, phase modulated, or amplitude modulated drives; stochastic drives, random and pseudorandom drives; combinations of drive elements and free precession delays or phase increments operable to enforce or approach closed loop magnetization trajectories after one or more pulse group operations; one or more time delays, stochastic time delays; phase increments; and time-varied magnetic field gradients, time- varied magnetic fields,.

[0024] Some embodiments of the invention include, a nuclear magnetic resonance nonrepeating sequence method with a tailored response function that is used to suppress the signal from water or other substances or to enhance the signal from one or more target substances in the sample. These non-repeating sequences comprise elements selected from the set of drive elements similar to those used in the repeating sequences.

[0025] Some embodiments include the case where the detected fields are used to create a spatial or spatio-temporal image according to the principles of chemical shift imaging (CSI) or magnetic resonance tomography (MRT), or spectroscopy, or spatial localization to facilitate target location. [0026] Some embodiments include the case wherein a modulation of the static magnetic field or reference frequency provides for a phase sensitive lock-in detection of the signals. Further embodiments include a feedback loop adjusting the modulation amplitude or phase. The magnetic field or the fields may be modulated to provide a reference for phase sensitive detection of the response of the sample.

[0027] Some embodiments include a sequence or sequences wherein the control pulse sequence is constructed and adjusted by control theory methods such as optimal control, maximum entropy, invariant operation group, geometric algebra, or Green's function methods.

[0028] Further embodiments include one or more of the following features. In some aspects, said method is operable to identify in said portion of said subject at least one member selected from the group consisting of a chromosomal composition, metabolite, blood gas, glucose, biomarker, bacteria, virus, infectious disease biomarker in a fetus, meningitis, subarachnoid hemorrhage, hydrocephalus, benign intracranial hypertension, cancer, inflammation, Multiple Sclerosis/Guillian-Barre, neurosyphillis, Down syndrome, Tay-Sachs, cystic fibrosis, genetic disease arising from chromosomal deletion, duplication, translocation, inversion, or ring formation, cholesterol, triglycerides, C- reactive protein, bilirubin, alkaline phosphatase, alanine aminotransferase, AST/GOT, TSH, creatinine, albumin, CK-MB, myoglobin, troponin I, B-type Natriuretic Peptide (BNP), cancer specific markers, cancer antigens, prostate specific antigen (PSA), cell count, cell morphology, pharmaceutical composition, or a therapeutic drug. In some aspects, said sample is at least one member selected from the group consisting of tissue, secretion products, excretion products, exogenous material, aminiotic fluid, bile, blood, blood plasma, cerumen, cowper's fluid, chyle, chyme, lymph, menses, breast milk, mucus, pleural fluid, pus, sebum, serum, urine, saliva, semen, sweat, tears, stool, ocular aqueous humor, pulmonary exhalate, phlegm, gastrointestinal gavage, pulmonary gavage, and skin, stem cells, bone marrow, cerebral spinal fluid, transplant tissue, skin tissue, or wound culture, or a flowing substance. In some aspects, the subject is a human or animal, or part thereof.

[0029] In some aspects, the concentration is derived from the following steps: exposing a sample or plurality of samples to electromagnetic field pattern so as to cause fields to emanate from a reference substance and said target substance; detecting said emitted fields from said reference substance and from said target substance; measuring an electrical signal corresponding to an amount of detected fields from said reference substance; measuring an electrical signal corresponding to an amount of detected fields from said target substance; calculating an attenuation factor based on said signal from said reference substance; correcting the signal of said target substance based on the attenuation factor; and determining an absolute concentration of said target substance in said subject from said corrected signal.

[0030] Further embodiments include the case where the reference substance is HbAlc, or water, or a form of glucose.

[0031] Further embodiments include a nuclear magnetic resonance system with a tailored response function operable to suppress the signal from water or other substances or to enhance the signal from one or more target substances in a sample. The system may be operable to determine a target resonance or resonances, generate an electromagnetic field pattern, expose a portion of said sample to said electromagnetic field pattern, detect said emitted fields from said target substance, analyze said emitted fields. The system comprises at least one of the following elements: a source of magnetic field comprising at least one of: a magnetic field system, a source of electromagnetic field patterns, a detector, a processor, a calculation system, or a calibrator.

[0032] The said magnetic field system comprises at least one of: a Halbach array of permanent magnets, a ferromagnetic pole system, an active and passive shim control, a field stabilizing lock-in system, RF shielding, or magnetic shielding.

[0033] The said source of electromagnetic field patterns that can cause fields to emanate from said target substance in a said sample, comprises at least one of: RF pulses, time varying RF pulses, time varying magnetic field gradients, time-varied magnetic fields, adiabatic pulses, or time delays.

[0034] The said detector to measure said emitted fields from said target substance fields comprises at least one of: a phase sensitive detector, a power detector, an RF receiver.

[0035] The said processor to analyze the said emitted fields comprises at least one of: a calculation system, wherein a frequency amplitude spectrum and a phase spectrum are constructed, a Fourier transform calculator, a correlation integrator, phase filtering process, an imaging system to determine the spin density distribution for one or more species, an imaging system to help determine a suitable location in said sample to expose said reference substance and said target substance comprising at least one of: a display and control system, an RF coil to excite the substance or target, a gradient coil to spatially encode the substance or target, RF electronics to receive control pulses and generate RF power to drive said RF coils, and control pulses and feedback circuitry for a field stabilizing lock- in system, gradient electronics to receive control pulses to drive x,y,z and shim coils in said gradient coils, a control waveform system to store digital control pulses, convert digital pulses to analog pulses and drive RF and gradient coils, an RF signal receiving system to amplify, filter, heterodyne, convert analog to digital waveform and process the digital signal suitable for display.

[0036] The said calculation system is operable to determine the absolute concentration of said target substance in said sample from said corrected measure of said target substance by exposing a sample or plurality of samples to the electromagnetic field pattern so as to cause fields to emanate from a reference substance and said target substance, detecting said emitted fields from said reference substance and from said target substance, measuring an electrical signal corresponding to an amount of detected fields from said reference substance, measuring an electrical signal corresponding to an amount of detected fields from said target substance, calculating an attenuation factor based on said signal from said reference substance, correcting the signal of said target substance based on the attenuation factor, determining an absolute concentration of said target substance in said sample from said corrected signal.

[0037] The said calibrator provides self-calibration based on an internal phantom sample, or an intrinsic element of the subject sample.

[0038] Some embodiments include the case where said source of electromagnetic field patterns is capable of exposing a sample of blood and detecting scattered fields from said sample to monitor in real time an analyte including, without limitation, a chromosomal composition, metabolite, blood gas, glucose, HbAlc, biomarker, bacteria, virus, infectious disease biomarker in a fetus, meningitis, subarachnoid hemorrhage, hydrocephalus, benign intracranial hypertension, cancer, inflammation, Multiple Sclerosis/Guillian-Barre, neurosyphillis, Down syndrome, Tay-Sachs, cystic fibrosis, genetic disease arising from chromosomal deletion, duplication, translocation, inversion, or ring formation, cholesterol, triglycerides, C-reactive protein, bilirubin, alkaline phosphatase, alanine aminotransferase, AST/GOT, TSH, creatinine, albumin, CK-MB, myoglobin, troponin I, B-type Natriuretic Peptide (BNP), cancer specific markers, cancer antigens, prostate specific antigen (PSA), cell count, cell morphology, pharmaceutical composition, or a therapeutic drug.

[0039] Further embodiments include a small and portable NMR device.

[0040] Further embodiments of the invention will readily appear to those skilled in the art from a review of the invention as disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Fig. 1 is a schematic view of an electromagnetic pulse train for magnetic resonance excitation and measurement.

[0042] Fig. 2 is a calculated magnetic resonance response from a one-pulse and one delay train (solid line) and a two-pulse and two delay train (dotted line) of a glucose and water sample, showing suppression of the water signal.

[0043] Fig. 3 is the calculated response of a multiple closed loop sequence.

[0044] Fig. 4 is a calculated magnetic resonance response from a stochastic pulse sequence with a single delay.

[0045] Fig. 5 is a calculated magnetic resonance response from a continuous pulse sequence with a single delay.

[0046] Fig. 6 is a calculated magnetic resonance response from an adiabatic pulse sequence with a single delay.

[0047] Fig. 7 is the measured response from glucose at 200 mM concentration dissolved in whole pig blood using a repetitive single pulse, single delay sequence.

[0048] Fig. 8 is a schematic view of a magnetic array system for creating a magnetic field.

[0049] Fig. 9 is a schematic view of an implementation of the magnetic resonance system of Fig. 8. DETAILED DESCRIPTION

[0050] A magnetic resonance, non- invasive, non-destructive system and method to detect molecules, in particular physiological analytes or biomarkers that are ex vivo, in vivo, or both, is provided. Specifically, magnetic resonance techniques are used to perform or facilitate otherwise difficult medical diagnostics or therapeutic treatments. Because of the nature of the technique, non-invasive detection is possible.

In one aspect, a method for generalizing the SSFP approach proposed by Carr to pulse trains of multiple discrete pulses and to continuous interactions is disclosed. See Figure 1. Pulse sequence 100 comprises pulses 101, 102, 103, and delay times 104, 105, 106. Instantaneous 'hard' pulses are commonly used. Other interaction elements can be placed in conjunction with or instead of the pulses. Examples include time varying pulses such as 'soft pulses', adiabatically swept drives, stochastic drives, and AM or FM drives. The drive elements are drawn schematically as soft pulses, though this is not restrictive. The delay times and phase increments can be varied depending on sequence design. In principle, a tailored behavior can be imposed upon a spin system through such methods. For the one pulse SSFP sequence, a large, but incomplete, suppression of the on-resonance signal, water, for instance, is possible whilst preserving a large off- resonance (glucose) signal. SSFP can be extended to a two pulse repetitive train. By varying the repetition time, TR, the pulses (frequencies, amplitudes, and phases), and the interpulse delay, tl, in principle, a complete suppression of the on-resonance spin, such as water, can be achieved whilst preserving a large off-resonance (such as underwater glucose) signal. A two delay sequence is described by (Wideband SSFP: Alternating Repetition Time Balanced Steady State Free Precession with Increased Band Spacing, Krishna Nayak, Hsu-Lei Lee, Brian Hargreaves, Bob Hu, Magnetic Resonance in Medicine 58:931-938 (2007), and S. I. Goncalves, M. L. W. Ziech, R. Lamerichs, J. Stoker, and A. J. Nederveen, Optimization of Alternating TR-SSFP for Fat-Suppression in Abdominal Images at 3T, Magnetic Resonance in Medicine 67:595-600 (2012)). This permits fat signal suppression, and a narrow stopband. Further, the one and two pulse SSFP sequence can be broadly extended to multiple pulses and delays. For example, a multiple time delay sequence, multiple-TR SSFP, is described by (Cukur and Nishimura, Multiple Repetition Time Balanced Steady-State Free Precession Imaging Magn. Reson. Med. 2009 July; 62(1): 193-204, and US 7,560,925 (2009) Nishimura, Dwight G., Cukur, Tolga, Multiple Repetition Time Steady-state Free Precession Imaging). Their approach aims to suppress fat further whilst maintaining a flat passband for water. Constant flip angle hard pulses are used rather than general time dependent drives. A further method, similar to the Dixon method (US 6,608,479 Method and System for MRI with Lipid Suppression, Dixon, William, Hardy, Christopher), for fat water separation is described in (US 7,518,364 (2009) Species Separation Using Selective Spectral Suppression in Balanced Steady State Free Precession Imaging, Cukur, T.). This method phase alternates images and combines them for the desired spectral response. The degree of suppression is important for metabolite detection given that the water signal is typically at least four orders of magnitude larger than a metabolite. In one aspect of the present invention, a phase filter of an SSFP sequence will produce similar passbands and stopbands. In another aspect, a generalized SSFP sequence is used to detect blood glucose non-invasively. For glucose detection applications, direct band-stop and bandpass methods must take into account the fact that the glucose resonance frequency is often overlapping with the much larger water peak. Under one aspect of the invention, the multiple TR SSFP sequence is extended to incorporate non-selective drive elements such as soft pulses, and adiabatic pulses, including time varying pulses with swept amplitude, phase, or frequency. Static adiabatic pulse, one pulse SSFP is described by (US 2010/026492 Spin Locked Ballanced Steady-State Free Precession (SL-SSFP), Walter Witschey, Mark Elliot, Ari Borthakur, Ravinder Reddy.) to provide a low power alternative to SSFP response profiles. Their approach is tailored for imaging needs. For example, the use of strong off-resonance spin lock drives make the sequence less frequency selective, but does provide a flat passband. Their approach does not include time-varying drives, nor multiple pulse and delay sequences. In the present invention, the drives are extended to the class of non-selective drives, and the sequence to multiple element patterns. In general, to reach a significant steady state magnetization, an effective B field must be generated that is lifted off of the xy plane. For Rabi frequencies large compared to the resonance offset of the drive to the Larmor frequencies, the sequence will not be strongly frequency discriminating and suitable for imaging; alternatively, for small Rabi frequencies, the sequence will be discriminating and thus suitable for spectroscopy.

[0051] The response of a one-pulse sequence is shown in Fig. 2 (201 solid line). Using a two-pulse sequence and representative values for relaxation (longitudinal relaxation, Tl, equals 10 times the transverse relaxation, T2) and frequency separation (25 Hz), a high discrimination of the positive frequency signal from the water signal is achieved, and is displayed in Fig. 2 (202 dotted line). The signal can be detected from a desired phase quadrant. The spin density of water (on resonance), alpha glucose (25 Hz), and other resonances (-80 Hz) is shown in grey (203). Additional refocusing pulses can also be used. In this example, the alpha glucose resonance is enhanced, while the water and other glucose resonances are suppressed. Further modifications may broaden the stopbands.

[0052] Under a repetitive pulse sequence, the trajectory of the spins in the Bloch sphere will at steady state form a closed loop, although the steady state is only approached dynamically. A repeated closed loop may be formed for a set of pulse and delay operations. Traditional SSFP forms a single repeated closed loop for each spin frequency. This behavior can be extended with a pulse sequence that forms multiple, distinct closed loop trajectories that may partially overlap. Since the available space of closed loops is continuous, the sequence does not have to be repeating, or may repeat after multiple distinct cycles.

[0053] The steady state behavior of spins will fall on an ellipsoid surface. The magnetization is: M_ss = (T₂ ² B_z B + σ_ζ + Τ₂σ_ζ X B)/(l + Ti T₂ (B_x ²+ B_y ²)+ T₂ ² B_z ²),where the effective drive magnetic field is: B=(o cOref )σ_ζ + CORabi (cos(0) σ_χ + sin(0) o_y). Here CO is the drive frequency, CQ-ef is the reference frame frequency, CORabi is the Rabi frequency, σ are the Pauli spin matrices, Ti and T₂ are the relaxation parameters The surface is determined by a balance between the relaxation and drive forces. The magnetization trajectories will cross the surface during each cycle.

[0054] Non-repeated pulse sequence patterns may also be used to create a response function that is steady in an averaged sense. For example, the SSFP trajectory for a given spin frequency undergoes a closed loop. However, there are multiple closed loops that intersect with this first loop. By adjusting the pulse sequence, a series of overlapping closed loops can be enforced, none of which are identical, but which at prescribed times give the same signal. The pulse sequence is not necessarily repeating.

[0055] Fig. 3 shows the frequency discrimination of a multiple closed loop sequence. 50 observations are averaged for each frequency point in the plot. The on-resonance signal, Mxy, is near maximum for the system parameters (Tl=800 ms, T2=80 ms), whereas it quickly is reduced for off-resonance spins. The flip angles were -0.032 +/- 0.004 radians, with delays of 8.7 +/- 1.1 ms.

[0056] The drive elements do not have to form a closed loop after each cycle, but may instead be driven by a random or pseudorandom sequence of pulse elements and delays. The average behavior, and variation about the average behavior, can be used to discriminate spin species.

[0057] Fig. 4 shows a stochastically driven sequence response wherein the drive flip angle and time delay are varied about mean values. The inset 401 shows the magnetization trajectories in the Bloch sphere for various frequency offsets. The correlations (rho) of the variances in magnetization compared to the resonance case are calculated. These show frequency discrimination, and are plotted in 402.

[0058] For spins of distinct frequencies some operations at certain points in the sphere are invariant or symmetric. For instance, a rotation about the axis direction of the magnetization of one spin will leave that spin magnetization the same, but will rotate a non-colinear spin. The z-axis and the origin are positions of particular interest. Placement of pulses whilst certain spins are located at these positions, and other spins are elsewhere, will give differential control of the spin species.

[0059] In another aspect, frequency discrimination may be attained through use of frequency selective drive elements such as soft pulses and adiabatic pulses.

[0060] Fig. 5 shows the response to a continuous drive. In 501 the dotted line is the response to a continuous drive with no delay. The grey line is the SSFP response. The solid line is response to the continuous drive with time delay. The phase profiles are shown in 502. The Rabi frequency is 1 Hz. [0061] Fig. 6 shows the response to an adiabatic drive (601) compared to a continuous drive (602). The adiabatic drive matches the continuous drive except for at odd nodes of the continuous drive response,

[0062] The Bloch sphere trajectory's approach to equilibrium can be influenced by a pre- sequence that places the trajectory along a desired direction, or by a non-repetitive pulse sequence such as a pulse train with flip angles that converge to a desired value. This pre- sequence can achieve a steady state solution, at which point the pre-sequence is abandoned and replaced by the steady state sequence that maintains the trajectory. Alternatively, the pre-sequence causes a converging approach to the targeted steady state, and the sequence is maintained. The signal from the approach to equilibrium may be used to advantage. In one aspect, a pre-sequence is combined with an extended SSFP sequence.

[0063] For a symmetric finite linewidth water peak, an SSFP sequence using an x pulse train produces an integrated signal from the transverse magnetization Mx, measured at an echo time that is half the repetition time (TE = TR/2), that is zero. However, the integrated signal from My is not zero. However, in one aspect, further pulses can adjust the steady state trajectories such that the total transverse magnetization is integrated to zero. In particular, an additional x pulse prior to detection, and a return x pulse after detection will result in a zero water signal at the detection time.

[0064] The pulse sequences described may also include elements, such as magnetic field gradients, to implement spatial or spatio-temporal imaging of the sample according to the principles of chemical shift imaging (CSI) or magnetic resonance tomography (MRT), or spectroscopy, or spatial localization to facilitate target location.

[0065] For example, the generalized SSFP system also may be utilized in a multiplexed fashion for chemical shift imaging. In particular, an SSFP image may indicate that certain points in the sample contain substantially more collagen than hemoglobin, and that other points in the sample contain substantially more hemoglobin than collagen. The points with more hemoglobin likely contain blood vessels, and the user can then attempt to obtain additional selective information from the blood vessels, e.g., make a measurement of glucose in the blood vessels. [0066] In one aspect, a method for measuring molecules in a sample is disclosed whereby modulation of the resonant frequency, either by changing the magnetic field or by changing the drive frequencies, gives a signal modulated at the modulation frequency or at a multiple of the modulation frequency depending on whether the slope of the response profile is linear or a higher polynomial order. Using standard lock- in frequency detection techniques, this approach can provide additional discrimination between two spin signatures such as water and alpha glucose.

[0067] Alternative to a rational design pulse sequence, a set of optimization criteria can be established, perhaps in conjunction with a rational design hypothesis, and a sequence solution numerically sought in a multidimensional parameter space including, for example, pulse amplitudes, phases, and delays. Optimal control theory, described by Borneman (Application of optimal control to CPMG refocusing pulse design, Borneman, T.W.; Hurlimann, M.D.; Cory, D.G., Journal of Magnetic Resonance, Volume 207, Issue 2, December 2010, Pages 220-233.) for the case of CPMG optimization, for example, also provides a means to make the signal robust against imperfections in the RF field. Further example methods to effect pulse sequence control design include maximum entropy methods, invariant operation group methods, geometric algebra methods, and Green's function methods.

[0068] By its nature, nuclear magnetic resonance is not restricted to measuring only one molecule species. Many target substances are in principle possible, and include: a chromosomal composition, metabolite, blood gas, glucose, HbAlc, biomarker, bacteria, virus, infectious disease biomarker in a fetus, meningitis, subarachnoid hemorrhage, hydrocephalus, benign intracranial hypertension, cancer, inflammation, Multiple Sclerosis/Guillian-Barre, neurosyphillis, Down syndrome, Tay-Sachs, cystic fibrosis, genetic disease arising from chromosomal deletion, duplication, translocation, inversion, or ring formation, cholesterol, triglycerides, C-reactive protein, bilirubin, alkaline phosphatase, alanine aminotransferase, AST/GOT, TSH, creatinine, albumin, CK-MB, myoglobin, troponin I, B-type Natriuretic Peptide (BNP), cancer specific markers, cancer antigens, prostate specific antigen (PSA), cell count, cell morphology, pharmaceutical composition, or a therapeutic drug. Furthermore, both in vivo and ex vivo measurements are possible. Target samples include: tissue, secretion products, excretion products, exogenous material, amniotic fluid, bile, blood, blood plasma, cerumen, Cowper's fluid, chyle, chyme, lymph, menses, breast milk, mucus, pleural fluid, pus, sebum, serum, urine, saliva, semen, sweat, tears, stool, ocular aqueous humor, pulmonary exhalate, phlegm, gastrointestinal gavage, pulmonary gavage, and skin, stem cells, bone marrow, cerebral spinal fluid, transplant tissue, skin tissue, wound culture, or a flowing substance.

[0069] The devices described herein may be used for quantitative in vivo testing of biological fluids and tissue for determining biochemical or hematological characteristics, or measuring the concentration of proteins, hormones, carbohydrates, lipids, drugs, toxins, gases, electrolytes, etc. If the absolute signal of an analyte molecule were constant, a non-invasive measurement of the analyte would also be constant, and variations in the detected signal could be directly related to variations in the underlying analyte quantity. This variation would depend only on the concentration of the analyte, the detection volume, and the detection method. In practice however, the detected signal of a constant concentration of the analyte is not constant. The signal varies with the degree of coupling of the sample to the detector. In the measurements described herein, when applied in vivo the precise composition of the various types of tissues of different electromagnetic properties, and the precise geometric relationship of these tissues to the electronic elements required for detection, alters the strength of the detected signal. For example, the skin's temperature, hydration and analyte composition will all vary over time and may cause varying levels of detected signal. In addition, these variations might be different from one person to another.

[0070] A calibration method can be used to correct for this variation. Specifically, to measure the absolute concentration of a physiologically or medically relevant substance ("target substance"), a container of a known quantity of a detectable molecule ("reference substance") can be placed in the detection volume either prior to the sample of interest or at the same time as the sample of interest. The resulting signal then provides an absolute calibration of the detection sensitivity. Multiple concentrations of the reference substance can be used to establish the linearity of the relationship between the detected signal and the substance concentration. The reference substance and the target substance volumes can be juxtaposed and discriminated by magnetic field gradient applications such that the reference and target measurements can occur simultaneously or in rapid succession allowing the absolute concentration of the target substance to be calculated by scaling the detected signal from the substance of interest to the detected signals from the reference substance samples of known concentration.

[0071] Alternatively, to measure the absolute concentration of a target substance, a different internal reference substance may be used to calibrate a concentration measurement of the target substance. Assuming that the target substance has a known essentially unchanging concentration, the abundance of both the reference substance and the target substance can be calculated from signal detected at the target site by one or more of the noninvasive detection methods described herein. The concentration of the target substance can be measured by any conventional means known to those skilled in the art, such as an enzymatic assay, HPLC, electrochemical assay, or mass spectrometry. The reference analyte should be selected such that its concentration does not change significantly over time (e.g., does not change significantly over a time period greater than a day, or greater than a week). In one embodiment a reference substance that occurs naturally in the body would be selected, but because many naturally occurring substances concentrations vary over time. An alternative embodiment is also envisioned in which a synthetic or implanted substance is used, to provide a reference substance concentration that does not change or changes slowly relative to the desired observation period (τ). By these methods, the system can be self-calibrating.

[0072] The spectroscopic methods and systems set forth here may be used, among other things, to non-invasively measure glucose concentrations in vivo. Preferably, a calibration phantom consisting of a range of glucose concentrations can be placed in the detection volume and used to provide an absolute concentration measurement of the target glucose substance.

[0073] Figure 7 shows the SSFP response spectrum from 200 mM glucose in whole porcine blood measured at 600 MHz proton frequency. The node of the SSFP was chosen to cancel the large water solvent peak (702). The spectrum exhibits incomplete suppression. The alpha peak (701) and the beta peak (703) are visible, as are the other glucose protons (704). The repetition time was 8 ms; and the acquisition time was less than a sec. For many averages, the signal to noise efficiency of the SSFP sequence should be superior to a presaturated experiment. An integration of the signal from the alpha or beta peaks should be proportional to the glucose concentration.

[0074] Alternatively, HbAlc may be used as an internal reference calibration standard. HbAlc is a subtype of hemoglobin A that is bound to glucose. The reverse reaction, or decomposition of glucose from hemoglobin proceeds relatively slowly, so that any buildup of this subtype will generally persist for roughly 4 weeks. HbAlc has a half- life in human blood that is -120 days, and is suitable for use as a calibration standard in the non-invasive spectroscopic methods described herein. Other suitable and long-lived species, such as fructosamine, that may be employed in the methods described herein will be evident to those skilled in the art.

[0075] The systems and methods described herein can also be used, for example, to obtain NMR signals from a urine sample contained in a flow tube. A catheter placed to collect the urine output from a patient can direct the flow past a flow meter, and then past an NMR detection volume. In the case of creatinine clearance measurement in urine, the multiplicative product of the flow rate and instantaneous creatinine concentration would give the desired creatinine clearance rate, i.e., a desired volume of blood plasma that is cleared of creatinine per unit time. The absolute value of the creatinine concentration can be calibrated from a neighboring reference cell, from an internal marker such as urea, or from a combination of these methods.

[0076] Detection of nuclear magnetic resonance signals require, usually, a high strength, uniform magnetic field, in addition to fast electronics to generate magnetic field gradients and to excite and detect the radiofrequency signals. Systems for medical applications include clinical 1.5 Tesla and 3.0 Tesla liquid cryogen cooled superconducting magnet based and lower magnetic field strength 0.2 T to 0.7 T permanent magnet based clinical MRI imaging scanners. Both types of systems are very large and heavy. Recent materials and engineering advances have enabled the production of lighter and smaller high homogeneity permanent magnet based systems. Furthermore, electronic technology advances have enabled miniaturization of the spectrometer and imaging system electronics.

[0077] A uniform magnetic field suitable for an appendage, such as a finger, wrist, or earlobe can be created from a Halbach array. The temperature and magnetic field homogeneity may be controlled actively and passively. The system of Fig. 8 shows an Eight-element Halbach array in a disk configuration. The elements are depicted by permanent magnet (PM) segments 811-818 and exhibit magnetization orientations 821- 828 that differ by 90° from segment to segment along the ring array. As is well known, this arrangement has the property of concentrating all the flux generated inside the cavity 840 while there is only minimal flux outside the disk. Furthermore, the flux 830 generated inside the cavity 840 forms a very uniform dipolar field. The dipolar field 830 can be further shaped by ferromagnetic pole elements. The poles can be designed as element 50 for both upper and lower poles. However, further field shaping can be accomplished if the pole can be structured as element 852 for both upper and lower poles. More complex pole contours are also possible but are not shown here.

[0078] The dipolar field 830 will require further field shimming accomplished by a combination of passive and active shimming. Ferromagnetic or PM pieces can be placed inside the cavity walls 840 and poles 850 or 852 to shim the magnet 800. Additionally, active shims are provided inside the gradient magnetic field coils for further shimming enabling the device the ability to shim electronically based on the condition of the subject to be analyzed.

[0079] Although system 800 is an Eight-element Halbach array, a sixteen-element, or more, Halbach array can be used for the magnet system. The geometry can also be circular in configuration including the cavity 840 and outer edges.

Fig. 9 depicts the device 900 that includes the electronic, digital, display and control systems. The system 900 is composed of the magnetic devices 300; the gradient coil set 930 and RF coil set 920, the display and control 910 and electronic control unit 940. The RF coils 920 excite the molecules in the subject to be analyzed and also serve to receive the signal from the molecules. The coils are formed from a solenoidal wire configuration. During the excite stage the signals are sent over the T control lines from the control unit 940. During the receive stage, the R control lines are used to collect the signal and the T lines are decoupled from the R control lines by a decoupling switch in the RF electronics unit inside 940. A lock-in system is also provided in the RF electronics unit inside 940 which uses a sense coil in the RF coil set 920 controlled through control line L to continuously sense the dipolar field from 800 and provide compensation dipolar field to keep the total field constant and minimize drift of dipolar field from 800. A cylindrical RF shield coil is placed inside the gradient coil set 930 to decouple the RF coil from the gradient coil.

[0080] Gradient coils 930 generate linear magnetic field variations along the dipolar field direction or the z direction as shown in Fig. 9 axis system 950. This is controlled through control line z of the Gradient electronics unit inside 940. The gradient coils 930 also generate linear magnetic field variations along the x and y axis directions of axis system 950 oriented in the dipolar field direction or z axis, and respectively controlled by control lines x and y of the Gradient electronics unit inside 940. The gradient coils each have an active shield integrated into the coil set 930 and controlled by the same control lines x, y and z of the Gradient electronics unit inside 940. Additionally, active shim coils for shimming dipolar field 930 are also integrated in the gradient coils 930 and controlled by the Gradient electronics unit inside 940 through control line s.

The control waveforms inside 940 activated through unit 910 generate a sequence of predetermined control waveforms that drive the RF and Gradient electronics units that in turn generate analog signals to drive the RF and Gradient coils. When a subject is being analyzed, these sequences of signals will interact with the subject through the magnetic fields of the RF and Gradient coils and stimulate the molecules in the subject to generate signals that are received by the RF coils and sent to the received signal processing unit inside 940. This unit will heterodyne the signal, condition it and send it to the display unit 910.

[0081] The disk magnet 800 will be magnetically and RF shielded to protect the RF coil 920 and the magnet 800 and to keep the stray field from it to acceptable levels such as 5 gauss or below.

[0082] In order to measure an absolute concentration of a metabolite such as glucose, a separate phantom consisting of a known quantity or quantities of the molecule or other reference molecules can be inserted in the device alongside the sample of interest. The signal from an actual in vivo measurement can then be directly compared to the reference standard, and an absolute concentration determination can be made. Alternatively, an intrinsic internal reference in the sample may be used. [0083] The embodiment of Fig. 9 may be suitable for use, for example, as part of a medical diagnostic or therapeutic device to locate a desired site, such as a blood vessel, within in the human body or animal or human subject. Once the desired site is located, an SSFP pulse sequence may be initiated to obtain the NMR spectrum of a target molecule within the detection volume. The present devices contemplated herein are suited for measuring blood glucose levels.

[0084] An embodiment of Fig. 9 may be small and portable, and suitable for use, for example, in the home, office, or public space as a medical monitoring device. The device may be for individual use, or for shared public use.

[0085] The invention having been fully described, it will be apparent to one of ordinary skill in the art that many modifications and changes may be made to it without departing from the spirit and scope of the present invention.

OTHER PUBLICATIONS

Principles of nuclear magnetic resonance in one and two dimensions, Richard R. Ernst, Geoffrey Bodenhausen, Alexander Wokaun, Oxford University Press, London/New York. 1987.

Human in vivo NMR spectroscopy in diagnostic medicine: clinical tool or research probe? PA Bottomley, GE Research and Development Center, Schenectady, NY 12301, Radiology, Vol 170, 1-15, 1989.

Steady-State Free Precession in Nuclear Magnetic Resonance, H. Y. Carr, Phys. Rev. 112, 1693-1701 (1958).

Principles and applications of balanced SSFP techniques, Klaus Scheffler, Stefan Lehnhardt, Eur Radiol (2003) 13:2409-2418.

Oppelt A, Graumann R, Barfub H, Fischer H, Hard W, Schajor W. 1986. FISP— a new fast MRI sequence. Electromedica 54(1): 15-18).

Frequency Stabilization Using Infinite Impulse Response Filtering for SSFP fMRI at 3T, Ming-Long Wu, Pei-Hsin Wu,Teng-Yi Huang,Yi-Yu Shih, Ming-Chung Chou, Hua-Shan Liu, Hsiao-Wen Chung, and Cheng- Yu Chen, Magnetic Resonance in Medicine 57:369-379 (2007).

Karla Miller, Stephen Smith, Peter Jezzard, John Pauly, High-Resolution FMRI at 1.5T Using Balanced SSFP, Magnetic Resonance in Medicine 58: 161-170 (2006).

WO 99/32897 (1999) NMR apparatus and method for no n- invasive in -vivo testing of a patient's body fluid glucose levels, Anderson, Marvin, H., Schleich, Thomas W., John Boban K., Schoolery, James N.

US 6,404,197 Bl (2002) Small scale NMR spectroscopic apparatus and method, Anderson, Marvin, H., Schleich, Thomas W., John Boban K., Schoolery, James N.

US 5,685,300 (1997) Noninvasive and in-vitro measurement of glucose and cholesterol by nuclear magnetic resonance spectroscopy, Kuenstner, J. Todd.

US 4,875,486 (1989) Instrument and method for non-invasive in vivo testing for body fluid constituents, Rapoport, U., and Panosh, R.

US 5,072, 732 (1991) NMR instrument for testing for fluid constituents, Rapoport, U., and Panosh, R.

Recovery of underwater resonances by magnetization transferred NMR spectroscopy (RECUR_NMR), Liu, M., Tang, H., Nicholson, J., Lindon, J. Journal of Magnetic Resonance 153, 133-137 (2001).

Uncovering hidden in-vivo resonances using editing based on localized TOCSY, Marjanska, M., Henry, P., Bolan, P., Vaughn, B., Seaquist, E., Gruetter, R., Ugurbil, K., Garwood, M., Magnetic Resonance in Medicine, 53(4): 783-789 (2005).

Application of optimal control to CPMG refocusing pulse design, Borneman, T.W.; Hurlimann, M.D.; Cory, D.G. Journal of Magnetic Resonance, Volume 207, Issue 2, December 2010, Pages 220-233.

Wideband SSFP: Alternating Repetition Time Balanced Steady State Free Precession with Increased Band Spacing, Krishna Nayak, Hsu-Lei Lee, Brian Hargreaves, Bob Hu, Magnetic Resonance in Medicine 58:931-938 (2007). S. I. Goncalves, M. L. W. Ziech, R. Lamerichs, J. Stoker, and A. J. Nederveen, Optimization of Alternating TR-SSFP for Fat-Suppression in Abdominal Images at 3T, Magnetic Resonance in Medicine 67:595-600 (2012).

Cukur and Nishimura, Multiple Repetition Time Balanced Steady-State Free Precession Imaging Magn. Reson. Med. 2009 July ; 62(1): 193-204.

US 7,560,925 (2009) Nishimura, Dwight G., Cukur, Tolga, Multiple Repetition Time Steady- state Free Precession Imaging.

US 7,518,364 (2009) Species Separation Using Selective Spectral Suppression in Balanced Steady State Free Precession Imaging, Cukur, T.

US 6,608,479 Method and System for MRI with Lipid Suppression, Dixon, William, Hardy, Christopher.

US 2010/026492 Spin Locked Ballanced Steady-State Free Precession (SL- SSFP), Walter Witschey, Mark Elliot, Ari Borthakur, Ravinder Reddy.

Claims

CLAIMS [0086] What is claimed is:

1. A nuclear magnetic resonance steady state method with a tailored response function operable to suppress the signal from water or other substances and to enhance the signal from one or more target substances in a sample comprising determining a target resonance or resonances,

generating a repeated electromagnetic field pattern comprising at least one of the following

continuous, non-instantaneous pulses, soft pulses, or spin lock drives,

adiabatic pulses, time varying, swept, frequency modulated, phase modulated, or amplitude modulated drives,

stochastic drives, random and pseudorandom drives,

combinations of drive elements and free precession delays or phase increments operable to enforce or approach closed loop magnetization trajectories after one or more pulse group operations,

one or more time delays, stochastic time delays,

phase increments,

time- varied magnetic field gradients, time- varied magnetic fields, exposing a portion of said sample to said electromagnetic field pattern operable to

drive the said target substance system toward or in a steady state cycle,

suppress the signal from water, other metabolites, or non-target resonances, enhance the signal from the target resonance or resonances,

cause fields to emanate from the said target substance in said sample,

detecting said emitted fields from said target substance,

analyzing said emitted fields.

2. A nuclear magnetic resonance non-repeating sequence method with a tailored response function operable to perform at least one of

suppression of the signal from water or other substances, enhancement of the signal from one or more target substances in a sample, comprising

determining a target resonance or resonances,

generating a non-repeated electromagnetic field pattern comprising at least one of the following

continuous, non-instantaneous pulses, soft pulses, or spin lock drives,

stochastic drives, random and pseudorandom drives,

one or more time delays, stochastic time delays,

phase increments,

drive the said target substance system toward or in a steady state cycle,

suppress the signal from water, other metabolites, or non-target resonances,

enhance the signal from the target resonance or resonances, cause fields to emanate from the said target substance in said sample,

detecting said emitted fields from said target substance,

analyzing said emitted fields.

3. The method of claim 1 or 2, wherein the signal is used for spatial or spatio- temporal imaging of the sample according to the principles of chemical shift imaging (CSI) or magnetic resonance tomography (MRT), or spectroscopy, or spatial localization to facilitate target location.

4. The method of claim 1 or 2, wherein the detection of the signal is arranged to be phase synchronous, thereby permitting a lock- in detection method comprising modulating the static magnetic field or reference frequency, detecting in a phase sensitive manner the response signals, frequency or phase filtering the detected signals,

adjusting the modulation amplitude or frequency based on the detected signals in a feedback manner.

5. The method of claim 1 or 2, wherein the control pulse sequence is constructed and adjusted by control theory methods comprising at least one of

optimal control methods

maximum entropy methods

invariant operation group methods geometric algebra methods

Green's function methods.

6. The method of claim 1 or 2, wherein said method is operable to identify in a portion of said sample at least one member selected from the group of substances consisting of

a chromosomal composition, metabolite, blood gas, glucose, HbAlc,biomarker, bacteria, virus, infectious disease biomarker in a fetus, meningitis, subarachnoid hemorrhage, hydrocephalus, benign intracranial hypertension, cancer, inflammation, Multiple Sclerosis/Guillian-Barre, neurosyphillis, Down syndrome, Tay-Sachs, cystic fibrosis, genetic disease arising from chromosomal deletion, duplication, translocation, inversion, or ring formation, cholesterol, triglycerides, C-reactive protein, bilirubin, alkaline phosphatase, alanine aminotransferase, AST/GOT, TSH, creatinine, albumin, CK-MB, myoglobin, troponin I, B-type

Natriuretic Peptide (BNP), cancer specific markers, cancer antigens, prostate specific antigen (PSA), cell count, cell morphology, pharmaceutical composition, or a therapeutic drug,

and said sample is of animal or human origin and is at least one member selected from the group consisting of

tissue, secretion products, excretion products, exogenous material, aminiotic fluid, bile, blood, blood plasma, cerumen, cowper's fluid, chyle, chyme, lymph, menses, breast milk, mucus, pleural fluid, pus, sebum, serum, urine, saliva, semen, sweat, tears, stool, ocular aqueous humor, pulmonary exhalate, phlegm, gastrointestinal gavage, pulmonary gavage, and skin, stem cells, bone marrow, cerebral spinal fluid, transplant tissue, skin tissue, wound culture, or a flowing substance.

7. The method of claim 1 or 2, wherein the concentration of the target substance is derived from the following steps exposing a sample or plurality of samples to the electromagnetic field pattern so as to cause fields to emanate from a reference substance and said target substance,

detecting said emitted fields from said reference substance and from said target substance,

measuring an electrical signal corresponding to an amount of detected fields from said reference substance,

measuring an electrical signal corresponding to an amount of detected fields from said target substance,

calculating an attenuation factor based on said signal from said reference substance,

correcting the signal of said target substance based on the attenuation factor,

determining an absolute concentration of said target substance in said sample from said corrected signal.

8. The method of claim 7, wherein said reference substance is HbAlc, or water, or a form of glucose.

9. A nuclear magnetic resonance system with a tailored response function operable to suppress the signal from water or other substances or to enhance the signal from one or more target substance in a sample and operable to

determine a target resonance or resonances,

generate an electromagnetic field pattern comprising at least one of the following

continuous, non-instantaneous pulses, soft pulses, or spin lock drives,

adiabatic pulses, time varying, swept, frequency modulated, phase modulated, or amplitude modulated adiabatic drives, stochastic drives, random and pseudorandom drives,

combinations of drive elements and free precession, delays or phase increments operable to enforce closed loop magnetization trajectories after one or more pulse group operations, one or more time delays,

phase increments,

time- varied magnetic field gradients, time- varied magnetic fields, expose a portion of said sample to said electromagnetic field pattern operable to

drive the said target substance system toward or in a steady state cycle,

suppress the signal from water, other metabolites, or non-target resonances,

detect said emitted fields from said target substance,

analyze said emitted fields,

and comprising at least one of the following elements

a source of magnetic field comprising at least one of

Halbach array of permanent magnets,

ferromagnetic pole system,

active and passive shim control,

field stabilizing lock-in system,

RF shielding,

magnetic shielding, a source of electromagnetic field patterns that can cause fields to emanate from said target substance in a said sample, comprising at least one of

RF pulses,

time varying RF pulses,

time varying magnetic field gradients, time- varied magnetic fields, adiabatic pulses,

time delays,

a detector to measure said emitted fields from said target substance fields comprising at least one of

phase sensitive detector,

power detector,

RF receiver,

a processor to analyze the said emitted fields comprising at least one of calculation system, wherein a frequency amplitude spectrum and a phase spectrum are constructed,

Fourier transform calculator,

correlation integrator,

phase filtering process,

imaging system to determine the spin density distribution for one or more species,

imaging system to help determine a suitable location in said sample to expose said reference substance and said target substance comprising at least one of

a display and control system,

an RF coil to excite the substance or target, a gradient coil to spatially encode the substance or target, RF electronics to receive control pulses and generate RF power to drive said RF coils, and control pulses and feedback circuitry for a field stabilizing lock-in system, gradient electronics to receive control pulses to drive x,y,z and shim coils in said gradient coils,

a control waveform system to store digital control pulses, convert digital pulses to analog pulses and drive RF and gradient coils,

an RF signal receiving system to amplify, filter, heterodyne, convert analog to digital waveform and process the digital signal suitable for display,

a calculation system, operable to determine the absolute concentration of said target substance in said sample from said corrected measure of said target substance by

exposing a sample or plurality of samples to the electromagnetic field pattern so as to cause fields to emanate from a reference substance and said target substance,

correcting the signal of said target substance based on the

F attenuation factor, determining an absolute concentration of said target substance in said sample from said corrected signal.

a calibrator, wherein the signal is self-calibrating based on an internal phantom sample, or an intrinsic element of the subject sample.

10. The system of claim 9, wherein said source of electromagnetic field patterns is capable of exposing a sample of tissue and detecting scattered fields from said sample to monitor in real time a substance comprising at least one of

Natriuretic Peptide (BNP), cancer specific markers, cancer antigens, prostate specific antigen (PSA), cell count, cell morphology, pharmaceutical composition, or a therapeutic drug.

11. The system of claim 9, which is a small and portable device.

12. A method to detect a target substance in a sample using nuclear magnetic resonance comprising:

determining a target resonance or resonances,

generating a repeated electromagnetic field pattern,

exposing a portion of said sample to said electromagnetic field pattern operable to

drive the said target substance system toward a steady state cycle, suppress the signal from water, other metabolites, or non-target resonances,

enhance the signal from the target resonance or resonances, cause fields to emanate from the said target substance in said sample;

detecting said emitted fields from said target substance;

analyzing said emitted fields.

13. The method of claim 12, wherein the electromagnetic field pattern comprises a discrete phase cycled pulse and a time delay;

14. The method of claim 12, wherein the electromagnetic field pattern comprises at least one of the following:

a repeated pattern comprising at least one of the following:

two or more discrete pulses, time delays, continuous field segments, and magnetic field gradients;

a non-repeated pattern comprising at least one of the following:

discrete pulses, time delays, continuous field segments and magnetic field gradients;

15. The method of claim 12, wherein the said target substance is glucose and the said target resonance is the alpha glucose resonance.

16. The method of claim 12, wherein the said sample is a human or animal subject.

17. The method of claim 12, wherein the concentration of the target substance is derived from:

exposing a sample or plurality of samples to the electromagnetic field pattern so as to cause fields to emanate from a reference substance and said target substance; detecting said emitted fields from said reference substance and from said target substance;

measuring an electrical signal corresponding to an amount of detected fields from said reference substance;

measuring an electrical signal corresponding to an amount of detected fields from said target substance;

calculating an attenuation factor based on said signal from said reference substance;

correcting the signal of said target substance based on the attenuation factor; and

18. The method of claim 12, further comprising imaging said impinged portion of said sample to help locate where said substance may be present in said subject.

19. The method of claim 12, wherein said portion of said sample is at least one member selected from the group consisting of tissue, secretion products, excretion products, exogenous material, aminiotic fluid, bile, blood, blood plasma, cerumen, cowper's fluid, chyle, chyme, lymph, menses, breast milk, mucus, pleural fluid, pus, sebum, serum, urine, saliva, semen, sweat, tears, stool, ocular aqueous humor, pulmonary exhalate, phlegm, gastrointestinal gavage, pulmonary gavage, and skin, stem cells, bone marrow, cerebral spinal fluid, transplant tissue, skin tissue, or wound culture.

20. The method of claim 12, wherein said method is operable to identify in said portion of said sample at least one member selected from the group consisting of a chromosomal composition, metabolite, blood gas, glucose, biomarker, bacteria, virus, infectious disease biomarker in a fetus, meningitis, subarachnoid hemorrhage, hydrocephalus, benign intracranial hypertension, cancer, inflammation, Multiple Sclerosis/Guillian-Barre, neurosyphillis, Down syndrome, Tay-Sachs, cystic fibrosis, genetic disease arising from chromosomal deletion, duplication, translocation, inversion, or ring formation, cholesterol, triglycerides, C-reactive protein, bilirubin, alkaline phosphatase, alanine aminotransferase, AST/GOT, TSH, creatinine, albumin, CK-MB, myoglobin, troponin I, B-type Natriuretic Peptide (BNP), cancer specific markers, cancer antigens, prostate specific antigen (PSA), cell count, cell morphology, pharmaceutical composition, or a therapeutic drug.

21. The method of claim 17, wherein said reference substance is HbAlc, or water, or a form of glucose.

22. The method of claim 12, wherein at least a portion of the sample is exposed under flow conditions.

23. The method of claim 12, wherein the signals are used for spatial or spatio- temporal imaging the sample according to the principles of chemical shift imaging (CSI) or magnetic resonance tomography (MRT).

24. The method of claim 12, wherein

the sample contains a target substance and water,

the electromagnetic field pattern comprises one or more discrete pulses and one or more time delays, operable to

place a portion of the water steady state trajectory on the z-axis of the Bloch sphere,

enhance the transverse magnetization signal from the target substance resonance.

25. A method to alter the approach to a steady state cycle in a SSFP-like sequence using a sequence of elements comprising at least one of

time varied magnetic field gradients,

discrete RF pulses at least partially in the transverse plane, continuous drive patterns causing adiabatic transformations,

spin lock drives,

non-uniform in time, amplitude, phase, or frequency pulse trains.

26. A method to enhance the detection of signals from an SSFP-like operation comprising:

modulating the static magnetic field or reference frequency, detecting in a phase sensitive manner the response signals, frequency filtering the detected signals,

adjusting the modulation amplitude or frequency based on the detected signals.

27. A system to detect a target substance in a sample using magnetic resonance comprising:

a source of electromagnetic field patterns that can cause fields to emanate from said target substance in a said subject,

a detector to measure said emitted fields from said target substance and, a processor to analyze the said emitted fields.

28. The system of claim 27, further comprising a processor to calculate the concentration of said target substance in said sample from said emitted fields.

29. The system of claim 27, wherein the source of magnetic field arises from a

system comprising at least one of:

Halbach array of permanent magnets

A ferromagnetic pole system

Active and passive shim control

A field stabilizing lock-in system

RF shielding

Magnetic shielding

30. The system of claim 27, further comprising an imaging system to help determine a suitable location in said sample to expose said reference substance and said target substance using:

a display and control system,

an RF coil to excite the substance or target,

a gradient coil to spatially encode the substance or target,

RF electronics to receive control pulses and generate RF power to drive said RF coils, and control pulses and feedback circuitry for a field stabilizing lock-in system,

gradient electronics to receive control pulses to drive x,y,z and shim coils in said gradient coils,

an RF signal receiving system to amplify, filter, heterodyne, convert analog to digital waveform and process the digital signal suitable for display.

31. The system of claim 27, wherein an attenuation factor is calculated by:

a source of electromagnetic field patterns that can cause fields to emanate from a reference substance in a sample;

a detector to measure said emitted fields from said reference substance; a processor to calculate an attenuation factor based on said measure of emitted fields from said reference substance, to correct said measure of emitted fields from said target substance based on said attenuation factor; and to determine an absolute concentration of said target substance in said sample from said corrected measure of said target substance.

The system of claim 27, further comprising an imaging system to help determine a suitable location in said sample to expose said reference substance and said target substance. The system of claim 27, wherein said source of electromagnetic field patterns is capable of exposing a sample of tissue and detecting scattered fields from said sample to monitor a blood glucose level in real time.

The system of claim 27, wherein said source of electromagnetic field patterns is capable of exposing a sample of tissue and detecting scattered fields from said sample to monitor blood lipid or triglyceride levels in real time.