WO2000069336A9 - Sodium magnetic resonance imaging used in diagnosing tumors and assessing response to treatment - Google Patents
Sodium magnetic resonance imaging used in diagnosing tumors and assessing response to treatmentInfo
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- WO2000069336A9 WO2000069336A9 PCT/US2000/013186 US0013186W WO0069336A9 WO 2000069336 A9 WO2000069336 A9 WO 2000069336A9 US 0013186 W US0013186 W US 0013186W WO 0069336 A9 WO0069336 A9 WO 0069336A9
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- magnetic resonance
- sodium
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/5607—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reducing the NMR signal of a particular spin species, e.g. of a chemical species for fat suppression, or of a moving spin species for black-blood imaging
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/483—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy
- G01R33/4838—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy using spatially selective suppression or saturation of MR signals
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/5602—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T436/00—Chemistry: analytical and immunological testing
- Y10T436/24—Nuclear magnetic resonance, electron spin resonance or other spin effects or mass spectrometry
Definitions
- BACKGROUND In vi tro cytotoxicity assays can provide preliminary information about the activity of an antineoplastic agent against a particular solid tumor. These techniques are limited not only by the difficulties in obtaining fresh tumor tissue for culture, but also in culturing human cells in explant. In vivo assessment of antineoplastic activity is limited by the length of time required for a change in size in a measurable soft tissue lesion to occur, which can sometimes be weeks. Moreover, some cancers metastasize predominantly in bone, and cannot be accurately measured by computer tomography (CT) or magnetic resonance imaging (MRI) . Therefore, some patients have ineffective drugs administered needlessly until clear progression is observed in a CT scan or MRI, or clinical symptoms worsen.
- CT computer tomography
- MRI magnetic resonance imaging
- NaJ Changes in intracellular sodium [NaJ have been described in a variety of biological systems during normal and pathophysiological events relevant to chemotherapy, including movement through the cell cycle, apoptosis, necrosis and transformation from normal to neoplastic tissue.
- Sodium nuclear magnetic resonance (Na-NMR) and Na-MRI were used in assessing intracellular sodium changes in vivo and to follow the effects of chemotherapy on a tumor [NaJ .
- Flow cytometry, fluorescent indicators, and atomic absorption spectroscopy was used in parallel cell culture experiments to establish cell death or cellular dysfunction and changes in intracellular [NaJ during antineoplastic exposure in vi tro.
- Detailed postmortem studies with immunohistofluorescence and culturing of tumor cells provided further confirmation of the link between cell ions and in vivo response to antineoplastics .
- Na-NMR is a particularly useful tool for the study of physiological and pathophysiological processes.
- intracellular concentration of H+ (pH) and Na+ [NaJ is correlated with the proliferation rate of nonneoplastic and malignant cell populations (13).
- Increased [NaJ is presumably related to the role of Na+ influx in initiating movement through the cell cycle, and to Na+ linkage by transmembrane exchangers to both Ca++ and H+ (51, 54) .
- SQ NMR single quantum NMR
- EC extracellular
- IC intracellular
- SRs paramagnetic shift reagents
- An alternative MR approach to measure IC Na content is based on the interaction of Na polyanions and their resultant effects on nuclear spin transitions; spin 3/2 nuclei (such as Na and K) have a nonvanishing quadrupole moment, allowing interaction with electrostatic field gradients (EFG) (30) .
- EFG electrostatic field gradients
- MQ multiple quantum
- spin transitions occur which can be detected by specific pulse sequences -- multiple-quantum filters (71, 72, 20, 69, 81, 95, 45) .
- pulse sequences -- multiple-quantum filters 71, 72, 20, 69, 81, 95, 45
- the presence of an MQ signal can be used to identify populations of Na nuclei by their molecular environment and to detect changes in [NaJ without the use of shift reagents (18, 20, 37, 39, 91, 92, 20b) . 4
- This invention uses sodium MRI rather than the traditional proton MRI or phosphorous MRI.
- Sodium MRI is currently an ignored area in the field of commercial clinical imagers.
- Na-MRI has failed to reach its full potential due to problems with discerning intracellular from extracellular populations of sodium nuclei. Shift reagents, which can be used in some experimental systems, are prohibited clinically.
- This invention distinguishes a responsive population of sodium nuclei, intracellular in origin, which responds to chemotherapeutic agents.
- this experiment weights these sodium MR images to enhance the contribution of the responsive population of sodium nuclei. Since this is done, using single quantum pulse sequences, it is readily applicable in current clinical imaging systems.
- This invention utilized two human tumor lines as subjects and two representative drugs as antineoplastic agents (both of significant clinical importance, having different modes of action) illustrate that the disclosed technique can detect the response to the chemotherapy administered at an equivalent human dose level.
- Defining intracellular concentration in a subcellular micro environment requires precise definitions of the dimensions of the physical domain of interest, its particular cellular location, the time frame over which the measurement is made, and the definition of concentration (as distinct from activity) . It has long been known that determining intracellular sodium and total sodium with measurements based on ion selective micro electrodes, fluorescent dyes, atomic absorption spectroscopy, single quantum Na NMR, multiple quantum filtered Na NMR, electron probe microanalysis or flame photometry give different values.
- a novel aspect of the MRI acquisition procedure described herein is the use of two different weightings (a weighted image and a non-weighted image) and the quantitative use of these two images to numerically derive two additional images which represent average estimated spatial profiles of important pathophysiological parameters of great clinical interest.
- the phantoms represent known and spatially homogeneously distributed values of the two parameters, it is possible to link the two derivative images to real units and values.
- the deficiencies of the prior art are substantially ameliorated in accordance with the present invention, which is, in one aspect, an optimized sodium magnetic resonance imaging technique for enhancing intracellular sodium and diagnosing of tumors and their response to chemotherapy.
- the present invention provides a method for acquiring magnetic resonance data from a sample comprising (a) applying a radio frequency pulse to a sample in a magnetic field, thereby causing alignment of nuclei populations within the sample; (b) applying a radio frequency pulse at a set time interval (TJ , thereby causing a measurable signal in the transverse plane; (c) suppressing a nuclei population in the sample by suitably selecting (TJ or by applying a multiple quantum filter; (d) applying image encoding for signal acquisition of the sample in (a) ; (e) detecting and analyzing the output signal to obtain a weighted image; (f) applying the magnetic field to the sample in (a) ; (g) detecting and analyzing the output signal to obtain an unweighted image; and (h) comparing the weighted and unweighted images.
- the present invention provides a method of determining the effectiveness of chemotherapy comprising (a) administering a dose of an antineoplastic agent to a subject prior to surgical removal of a cancerous tumor, (b) applying the method for acquiring magnetic resonance data from the subject; and (c) using the data obtained by applying the method for acquiring magnetic resonance data to determine if the antineoplastic agent has altered the nuclei populations in the subject.
- the present invention provides a method for detecting and characterizing tumors in a subject comprising (a) applying the method the method for acquiring magnetic resonance data to the subject, and (b) using the data obtained by applying the method for acquiring magnetic resonance data to determine the nuclei populations in the subject .
- the present invention provides a method for determining cell death or cellular dysfunction in a subject by (a) applying the method for acquiring magnetic resonance data to the subject; (b) using the data obtained by applying the method for acquiring magnetic resonance data to determine the nuclei populations in the subject; and (c) comparing the weighted and unweighted images.
- FIG. 2 Comparison of two cell lines and two pulse sequences -
- a plastic animal platform was constructed to which were glued two reference phantoms of 200 mMol/L NaCl with either 30% Ficoll (PI) or 40% Ficoll (P2) .
- the 40% phantom is the brightest phantom on the IR image and the 30% phantom the brightest on the SQ image.
- PI Ficoll
- P2 40% Ficoll
- panels C & D show a single quantum (left panels, A & C) , and inversion recovery acquisitions (right panels, B & D) .
- Enhanced FITC fluorescence indicated reorientation of phosphatidylserine within the cell membrane.
- PI was added to detect dead cells, which was both PI and annexin positive, the latter response due to internal binding of an antibody to phosphatidylserine sites accessed through membrane rupture.
- Control cells were mostly PI and FITC negative.
- the percentage of live PC3 cells that were annexin positive (vertical axis) is plotted versus time (horizontal axis) for taxotere (10 nM; filled circles) and VP-16 (10 ug/ml; filled triangles).
- FITC intensity A one dimensional annexin histogram (FITC intensity) for live cells is shown for control (bottom insert) and after 24 hrs VP-16 (top insert) .
- FITC intensity A one dimensional annexin histogram for live cells is shown for control (bottom insert) and after 24 hrs VP-16 (top insert) .
- Flow cytometry was performed on the Becton/Dickenson FACStar II (APO-BrdU) or exCaliber flow system (Annexing) at the Columbia University Cancer Center and analyzed using CellQuest Software.
- (A) Graphs of normalized image intentsity versus time.
- (B) Graph of mitotic figure/field versus IA change. The y-axis is the mean mitotic figures and the x-axis is the IR intensity change. 12
- mice post chemotherapy The MRI studies on individual mice post chemotherapy is limited by the limited life time of nude mice outside the sterile animal barrier. We can readily acquire control images, with 1-2 post chemotherapy re-imagings at intervals of 24 to 72 hours. In most cases mice survived several days and were sacrificed while showing no signs of behavior or health impairment.
- the anesthetized mouse was aligned in a deep grove with the tumor positioned through a small elliptical opening, thus maintaining the same relative position from experiment to experiment and routinely aligning the tumor just slightly above the plane defined by the two phantoms.
- B The image of an immunofluorescent slide of the 13 tumor from figure 5A is shown.
- the DNA is fluorescently endlabelled on slides using the APO-BRDU kit (Pheonix Flow Systems) adapted from flow cytometry (figure 3A) .
- the bright area on this digitized image indicates apoptotic cells occurring within the dark surviving rim, but outside of the necrotic center.
- This figure shows effect of 6 mg taxotere on a carcinogen (MNU) induced breast tumor in a Spraque Dawley rat.
- the weighted (IR) images become brighter after the treatment.
- a proton image of the mouse is shown along with companion IR and SQ sodium images from a tumor bearing mouse.
- Proton SQ sodium, and IR sodium images are shown for the same approximate slice location.
- the subcutaneous PC3 cell prostrate cancer tumor and kidneys are clearly visible on the proton image.
- the kidneys, which are bright on the SQ image with no inversion pulse, are suppressed in the IR sodium image.
- the tumor is enhanced in the sodium IR image.
- the proton image was acquired with a 2D spin echo sequence, TE/TR was 25 ms/700 ms, slice thickness was 3 mm, NEX was 2, and acquisition matrix was 256x256.
- SQ and IR Na images were acquired with 3D gradient echo based sequences with 14 acquisition matrix 64x64x12.
- the nude mouse was positioned in a special holder to which were permanently attached two reference phantoms (left and right respectively were 30% and 40% Ficoll in 200 mM NaCl) .
- the tumor was positioned through a small oval opening in the holder platform, which standardized its position with reference to the phantoms. This allowed for reproducibly positioning the tumor and body during different imaging sessions.
- the proton and sodium quadrature birdcage coils employed here are identical in dimension .
- the present invention provides a method for acquiring magnetic resonance data from a sample comprising (a) applying a radio frequency pulse to a sample in a magnetic field, thereby causing alignment of nuclei populations within the sample; (b) applying a radio frequency pulse at a set time interval (TJ , thereby causing a measurable signal in the transverse plane; (c) suppressing a nuclei population in the sample by suitably selecting (TJ or by applying a multiple quantum filter; (d) applying image encoding for signal acquisition of the sample in (a) ; (e) detecting and analyzing the output signal to obtain a weighted image; (f) applying the magnetic field to the sample in (a) ; (g) detecting and analyzing the output signal to obtain an unweighted image; and (h) comparing the weighted and unweighted images.
- the radio frequency pulse is 180° followed by 90°.
- the radio frequency pulse includes but is not limited to selective, nonselective, single or composite, sine, sech or tyco.
- the data acquired is two- dimensional data or three-dimensional data.
- the data acquired includes but is not limited to with slice selection or without slice selection, with or without projection reconstruction, with or without spin-echo, with or without gradient echo.
- the magnetic field is generated by a magnet having an arbitrary field strength. In a further embodiment the magnetic field is generated by a magnet having a field strength of 1 to 5 tesla. In another embodiment the field strength is 1 to 15 tesla. In still another embodiment the method for acquiring magnetic resonance data the magnetic 16 field is generated by a magnetic coil having a field strength of 4.23 tesla
- the said magnetic coil is tuned for protons, sodium, nuclei of a single element or nuclei of multiple elements .
- the coil is tuned for sodium. In another embodiment the coil is multiple tuned.
- the present embodiment includes but is not limited to multiple tuning with or without use of surface coils.
- the magnet can be a single magnet or multiple magnets.
- the set time (TJ is the time which suppresses detection of a population of nuclei
- set time (TJ comprises the time which suppresses detection of a population of nuclei
- TJ is (ln2)T x
- T x is the longitudinal relaxation time of the suppressed nuclei.
- TJ includes but is not limited to 25 msec.
- suppression comprises minimization of the signal of a population of nuclei.
- suppression includes but is not limited to the use of phantoms.
- said detecting and analyzing is of intracellular and extracellular populations of nuclei.
- the intracellular and extracellular populations of nuclei have different longitudinal relaxation times.
- the weighted image and the unweighted image are compared.
- the weighted image and the unweighted image comparison includes 17 but is not limited to pixel to pixel, region to region, or algebraic .
- the methods of administration are to include, but are not limited to, administration cutaneously, subcutaneously, intravenously, parenterally, orally, topically, or by aerosol.
- the present invention provides a method for detecting and characterizing tumors in a subject comprising (a) applying the method for acquiring magnetic resonance data from the subject, and (b) using the data obtained by applying the method for acquiring magnetic resonance data from the subject to determine the nuclei populations in the subject.
- the present invention provides a method for determining cell death or cellular dysfunction in a subject comprising (a) applying the method for acquiring magnetic resonance data from the subject, and (b) using the data obtained by applying the method for acquiring magnetic resonance data from the subject to determine the nuclei populations in the subject.
- ech shall mean the hyperbolic segment of x 18
- the term "tyco” shall mean the composite pulse sequence for inversion of the signal magnetization.
- Doubly tuned coil - a coil which can be simultaneously tuned to two Larmer frequencies (for example, to those of protons and sodium), thus permitting MR acquisitions of both nuclei.
- Gradient echo - spin echo produced by reversing the direction of a magnetic field gradient or by applying balanced pulses of magnetic field gradient before and after a refocusing (RF pulse) so as to cancel out the position-dependent phase shifts that have accumulated due to the gradient.
- the gradient echo is generally adjusted to be coincident with the RF spin echo.
- Image acquisition time - time required to carry out an MR imaging procedure comprising only the data acquisition time.
- the total image acquisition time is equal to the product of the repetition time, TR; the number of signals averaged, NSA; and the number of different signals (encoded for position) to be acquired for use in image reconstruction.
- the additional image reconstruction time also is important to determine how quickly the image can be viewed. In comparing sequential plane imaging and volume imaging techniques, the equivalent image acquisition time per slice must be considered, as well as the actual image acquisition time.
- Magnetic field the region surrounding a magnet (or current- carrying conductor) .
- Magnetic field is a vector quantity; 19 the direction of the field is defined as the direction that the north pole of a small magnet points when in equilibrium.
- a magnetic field produces a magnetizing force on a body within it .
- Pixel - acronym for a picture element the smallest discrete part of a digital image display.
- Projection-reconstruction methods - essentially based on Fourier transformation of the free induction decay (FID) signals that are obtained by rotating a magnetic field gradient with subsequent back projection to determine the spin-density function.
- FID free induction decay
- Pulse, 90 degrees - Radiofrequency (RF) pulse designed to rotate the macroscopic magnetization vector 90 degrees in space as referred to the rotating frame of reference.
- RF Radiofrequency
- Pulse, 180 degrees - RF pulse designed to rotate the macroscopic magnetization vector 180 degrees in space as referred to the rotating frame of reference.
- Pulse sequences - set of RF (and/or gradient) magnetic field pulses and time spacings between these pulses; used in conjunction with magnetic field gradients and NMR signal reception to produce NMR images.
- Radiofrequency (RF) - wave frequency intermediate between auditory and infrared The principal effect of RF magnetic 20 fields on the body is power deposition in the form of heating, mainly at the surface.
- Selective excitation - controlling the frequency spectrum of an irradiating RF pulse (via tailoring) while imposing a magnetic field gradient or spins, such that only a desired region has a suitable resonant frequency to be excited.
- Slice the effective physical extent of the "planar" region being imaged.
- the slice thus imaged is the selected slice.
- Suppression one of a number of techniques designed to minimize the contribution of a particular spectral line to the detected signal. Most commonly used to suppress the strong signal from water in order to detect other components.
- T x - spin-lattice or longitudinal relaxation time the characteristic time constant for spins to tend to align themselves with the external magnetic field. Starting from zero magnetization in the z direction, the z magnetization will grow 63 percent of its final maximum value in a time T x .
- Tuning - process of adjusting the resonant frequency e.g., the Larmor frequency. 2 1
- Voxel - volume element the element of three-dimensional space corresponding to a pixel, for a given slice thickness.
- the practice of this invention includes the ability to assess the efficacy of a particular therapy at an early stage.
- Effective chemotherapy may lead to reduced F-18 fluorodeoxyglucose (FDG) uptake monitored by PET imaging (94), or, changes in cell metabolism using P-31 MR spectroscopy (44, 52, 75-78, 84).
- FDG F-18 fluorodeoxyglucose
- PET imaging 94
- P-31 MR spectroscopy 44, 52, 75-78, 84
- successful application of advanced Na-MRI techniques has yet to realized and could considerably enhance the promise of this approach.
- SQ NMR Single-quantum
- MQF multiple-quantum filtered Na-NMR- Due to the biological importance of Na, its relative abundance, and its sensitivity, Na-NMR is a particularly useful tool for the study of physiological and pathophysiological processes. Measurement of Na content clinically has typically been done, using SQ NMR techniques (4-6, 8, 11, 12, 25, 58, 74).
- a significant disadvantage of SQ NMR is due to the relatively larger abundance of extracellular (EC) versus intracellular (IC) [Na] . Attempts to discern [NaJ using only SQ NMR requires paramagnetic shift reagents (SRs) which have distinct disadvantages including: toxicity, possible drug interaction, expense, and impermeability to the blood brain barrier.
- SRs paramagnetic shift reagents
- MQ Na signals have been observed in cells (31, 71, 72, 86, 90) and tissues (20, 28, 32, 33, 70, 85), as well as in studies of proteins (10, 29, 69, 71, 72, 81, 82, 90) and polysaccharides (45, 46, 90) in solutions (phantoms) .
- Novel use of inversion recovery to weight Na MR Images An unexpected technical advance capturing the utility of multiple quantum Na-MRI in a single quantum framework.
- the higher signal to noise of single quantum Na-MRI make it more readily implemented using current clinical systems, thus allowing for manageable acquisition times without the need of paramagnetic shift reagents.
- Selection of subpopulations of Na nuclei based on relaxation times uses the longitudinal relaxation time (TJ rather than the transverse relaxation time (T 2 ) used by multiple quantum Na-MRI.
- TJ longitudinal relaxation time
- T 2 transverse relaxation time
- an inversion recovery (IR) pulse sequence is used to suppress signals from Na nuclei with long T x relaxation times. The goal was to set the inversion time at a value where Na in free extracellular solution was suppressed to produce an intracellular sodium weighted image.
- tissue culture studies provide baseline data, specifically cell cycle plots and endlabelling responses that compare treated and untreated cells in culture to cells dissociated from postmortem tumor explants.
- Tumors were removed from mice and examined histologically . Counts of the number of mitotic figures were significantly higher (p ⁇ 0.05) in tumors from non-treated than from treated mice. This confirms that the tumors in treated mice were affected in another measurable way in addition to the elevation of weighted image intensity.
- MTT microculture tetrazolium technique
- the IR pulse sequence may be used to suppress the contribution of sodium nuclei within a specific range of T l r e.g. a range centered about T lex . Having identified this range, one sets the inversion time to (In 2) (T le J , a good approximation for long repetition times.
- the inversion time is the time between the 180° and 90° pulses in the IR pulse sequence.
- the optimal T lex is a mean longitudinal relaxation time, whereby a composite signal, predominantly extracellular in origin, which acts to mask the functionally relevant changes can be suppressed.
- a 25 msec inversion pulse produced images with complete suppression of kidneys (compare curved arrows, panels C versus D, fig. 2.) and cystic tumors (image inserts, fig. 1).
- the inversion time producing the best suppression of fluid objects also produced the best relative enhancement of the tumor (fig. 2.; panel B, DU145 tumor; panel D, PC3 tumor).
- the relative enhancement of the tumors was readily apparent on 3-4 contiguous slices from each 3D image of 24 slices.
- a breast cancer tumor is imaged in an animal model.
- This image verifies that the imaging diagnostic described herein responds to the treatment of a different animal model when using a different tissue type as the neoplastic target.
- the tumor was induced by injecting a Sprague Dawley rat with carcinogen MNU.
- the rat was imaged using weighting and non-weighting pulse sequences.
- One rat was given a 3 mg intra venous injection of taxotere and a second was given a 6 mg injection of taxotere. Only the latter showed a response, illustrated in the figure (7) . Both the images became brighter, with the most dramatic proportional change occurring in the weighted image.
- paired proton and sodium quadrature birdcage magnetic coils identical in dimension, were tuned to obtain proton images immediately after the two Na images (with the animal position still maintained in the plastic animal platform) .
- a set of Proton, SQ sodium, and IR sodium image are shown for the same approximate slice location.
- Figure 8 The subcutaneous PC3 cell prostate cancer tumor and the kidneys are clearly visible on the proton image. The kidneys, which are bright on the SQ image with no inversion pulse, are suppressed in the IR sodium image. The tumor is enhanced in the sodium IR image.
- the proton image was acquired with a 2D spin echo sequence (two-dimensional data) , TE/TR was 25ms/700ms, slice thickness was 3 mm, NEX was 2, and acquisition matrix was 256x256.
- SQ and IR Na images were acquired with 3D gradient echo base sequences (three-dimensional data) with acquisition matrix 64x64x12.
- DNA fragmentation is not a requirement of apoptosis; since apoptosis can proceed in the presence of endonuclease inhibitors, which block DNA fragmentation. Therefore, a second earlier event in the apoptotic cascade will also be examined. Live cells will be exposed to an Annexin V / FITC conjugated antibody and then examined with flow cytometry. Enhanced fluorescence indicates reorientation of 31 phosphatidylserine within the cell membrane and identifies a very early cellular commitment to the apoptotic cascade (61, 93).
- Inversion recovery images (25 msec inversion time) were acquired for 16 nude mouse tumors following chemotherapy. Mice were positioned in a plastic holder with phantoms permanently attached just below the plane of the tumor, which protruded through a small whole in the platform. The slice with the brightest tumor region was used for analysis and normalized to the brighter phantom. Peak of the line profile is plotted through the center of the tumor, and for predrug (0 hrs) and two later times (24, 48 hrs). Taken separately, the change for each drug on PC3 cells was significant - taxotere induced a 32% increase (p ⁇ 0.001; Fig. 4. A) and VP-16 induced a 38% change (p ⁇ 0.0005; Fig. 4. B) .
- LNCaP is the slowest responding of the 3 lines with almost no response at 24 hrs, but significant DNA fragmentation at 44 hrs.
- antineoplastics e.g. taxotere (1 to 100 nM) , 9-amino-camptothecin (10-200 nM) , and VP-16 etoposide (1-100 ug/ml
- the cells to be used in such drug studies could either commercially available cell lines from ATCC, or cells dissociated from tumors (treated or untreated) .
- SBFI/AM is ratiometric (26, 35, 55) and is unaffected by variations in loading. However, its double wavelength ultraviolet excitation requirement is impractical for flow cytometry.
- Sodium green (3) uses standard Fluorescein excitation/emission wavelengths. Forward scattering is used to normalize for loading, or alternatively various Na+ insensitive fluorescent dyes (with different spectral properties but using similar loading mechanisms) are used. Using sodium green, propidium iodide (PI) , and forward scattering several populations in treated DU145 and PC3 cells were identified, one of which may be an apoptotic population with elevated [NaJ .
- PI propidium iodide
- tissue culture ionic meaurements can be made on commercially available, well studied cell culture lines. They can also be run to compare these results to those on primary cultures of cells from human tumors.
- Patterns of [Na] change can be examined in relation to an event in the apoptotic cascade, and for example, to drug and dose levels, or cell line.
- SBFI/AM Two dyes (both from Molecular Probes) were used for this purpose, SBFI/AM (26,55) and sodium green (3).
- Sodium green is designed for flow cytometry, and SBFI/AM, a dual excitation wavelength dye, is used in a fluorescent plate scanner.
- SBFI/AM a dual excitation wavelength dye
- cells can be treated and cultured and adherent in black (non fluorescent) 96 well plates and measure average [NaJ of the cells in each well.
- sodium green cell suspensions can be run through the fluorescence activated cell sorter, populations selected for subsequent fixation and further study, or, with proper controls and use of Na ionophores, measure [NaJ . By combining the two approaches it is possible to compare average [NaJ in treated versus untreated cells.
- a murine myocyte line (AT-1) in non athymic mice was propagated, since these mice could be subject to multiple imaging sessions.
- SQ and TQ images of a large ATI tumor were acquired and noted was the higher signal intensity in tumor compared to normal tissue in the Na images.
- there is a higher contrast between tumor and normal tissue in the TQ image compared to the SQ image due to the higher sensitivity of TQ NMR to [NaJ .
- Tumor propagated from the AT-1 myocyte cell line was used for an additional MR confirmation of the approach.
- a single tumor was removed and finely minced, then split in half and resuspended in two 50 ml Falcon tubes filled with oxygenated media.
- Triple quantum filtered sodium MR spectroscopy was utilized with a Bruker 400. After control spectra were acquired, the tissue was resuspended in fresh media.
- To one tube was added lonidamine and doxorubicin (adriamycin) . This combination was recommended as synergistic. At six hours, the two tubes were again examined and the treated tumor gave a clearly higher signal, indicating sodium elevation.
- the total cell content of Na can be determined with atomic absorption spectroscopy (AAS) for cell pellets (>300 mg; 89) trypsinized from culture dishes. This is a useful measurement since Na-NMR can measure changes in total Nai in the absence of a change in [NaJ . Examination of untreated cells in a pellet with AAS and revealed higher total [NaJ in LNCaP than in PC3 and DU145 cell lines. This is intriguing since LNCaP also has the highest level of ambient endlabelling fluorescence. These studies will be pursued and used in combination with AAS measurements on tumors removed after imaging.
- AAS atomic absorption spectroscopy
- Tumors had a central necrosis (coagulation or liquefaction type) with a surviving rim. Between the surviving rim and central necrosis was a region of apoptotic cells.
- Control images are acquired for each mouse to be treated. Both SQ and IR images are acquired. Proton MR images are acquired to define the underlying tumor structure. Potential [NaJ gradients associated with inhomogeneous distributions of necrotic tissue, rapidly growing cells (different cell cycle distribution) , and non-neoplastic tissues can be examined. High resolution line profiles are obtained at different regions of the tumor. Line profiles are more 3 9 rapidly acquired than full images and can be used to monitor real time changes. However, even using line profiles, with their reduced acquisition times, the triple quantum data described above was still noisy. Acquisition times are constrained to about 1-2 hours for rodent experiments, the time during which anesthetic remains active. For clinical studies, acquisition times would be constrained by considerations of patient comfort and ability to remain motionless, and utilization/cost criteria. Thus the inversion pulse technique described with its enhanced signal to noise ration, is a significant improvement over the triple quantum filtering technique.
- mice Prior to recovery from the final imaging session, mice were sacrificed, tumors recovered, fixed in 10% formalin and sectioned. Some sections can be: i) flash frozen for later histology and immunohistochemistry as required; ii) washed in PBS, treated with collagenase, suspended in serum containing medium, cultured or fixed for later flow cytometry study; or, iii) blotted and placed in liquid nitrogen for later AAS analysis.
- a 100 ⁇ L injection of 80 mM potassium cobaltic EDTA in saline is injected in a femoral artery (83, 96) .
- Adequacy of in vivo drug levels can also be assessed by comparing flow cytometric data of cells fixed from treated tumors versus those cultured directly from commercial stocks. Parameters like cell cycle distribution and endlabelled DNA strand breaks (both from fluorescent stained DNA) are sufficiently stable during the approximately 2 hrs required to disperse and fix the cells.
- Image intensity is examined as a function of propagating cell line and tumor size, and compared to normal tissue. High resolution line profiles are examined for relative changes following chemotherapy. Such changes indicate a rapid and 40 measurable response to chemotherapy.
- needle biopsies can be performed to histologically assess the effects of drugs on cell morphological and immunological status. If tumor removal is undertaken at this time, complete studies of morphology, proliferation index
- apoptosis can then be performed.
- One goal in performing imaging studies on tumors prior to removal is to examine the drug sensitivity profile of the tumor cells in order to more effectively perform profylactic treatment of potential metastasis.
- Late events - DNA strandbreaks Fixed cells (treated and control) have DNA strandbreaks (Phoenix Flow Systems, APO-Brdu KIT) and total DNA (propidium iodide) fluorescent labeled. DNA fragmentation is quantitated by flow cytometry.
- Combination therapies with multiple imaging modalities- listings of NIH sponsored clinical cancer trials indicate the potential efficacy of combining traditional chemotherapy with anti-angiogenesis therapy.
- proton MRI can be used to assess blood vessel capacity, by employing well known techniques with contrast agents; the invention taught here could readily be employed with a doubly tuned or multiply tuned coil to generate co-registered proton images with weighted and unweighted sodium images.
- information on chemotherapy effectiveness could be attained concurrently with that on vessel capacity in "real time”. This would assist in developing new clinical protocols and testing combination drug therapies.
- 42 Analysis - FACS data is analyzed using software (CellQuest; Winmidi). Two dimensional histograms are used to examine endlabelling fluorescence versus PI, or annexin versus PI. In the former case, PI gives cell cycle information. In the latter, it allows for gating of dead cells.
- Sodium green - This dye can be used with flow cytometry.
- Cell [NaJ can be determined on selected populations of treated cells. Cells can be sorted based on [NaJ for subsequent fixation and additional flow cytometry.
- Sodium green can be used with annexin V by changing to a compatible chromophore (PE) on the annexin and using a propidium iodide substitute (7-AAD) with different fluorescent characteristics (both available from Pharmingen) .
- PE compatible chromophore
- 7-AAD propidium iodide substitute
- annexin cell membrane integrity, sodium green fluorescence and forward scattering can be simultaneously determined.
- ionophores monoensin, gramicidin
- a sodium insensitive dye with similar loading characteristics (e.g. calcein/AM, Molecular Probes).
- SBFI/AM This dual excitation wavelength dye is used in a fluorescent plate scanner.
- SBFI/AM we can treat cells cultured in black (non fluorescent) 96 well plates and measure average [NaJ of the cells in each well. [NaJ is calculated using ratio method and in situ calibration - thus ionophores (monensin and gramidicidin) eliminate the transmembrane gradient so that [NaJ can be altered by changing [NaJ .
- Analysis of flow cytometry is performed using standard one and two dimensional histograms and scatter plots.
- the total cell content of Na can be determined with atomic absorption spectroscopy (AAS) from cell pellets (89) trypsinized from culture dishes.
- AAS atomic absorption spectroscopy
- Large cell pellets are obtained from multiple plate cultures (x20 100mm plates) for each cell line. Total Na per cell and per dry weight of the pellet is obtained in triplicate for each cell population with or without prior treatment.
- the protocols are constrained by the maximum duration of imaging sessions. Thus a 90 min period of anesthetization during which animals are motionless can readily be attained.
- Na-MRI images - Control images are acquired for each mouse to be treated. Both single quantum (SQ) and inversion recovery sodium images are acquired. Since they are taken sequentially, they are coregistered.
- Proton MR images - Proton images are acquired to define the underlying tumor structure.
- tumors are to be removed for histological analysis, they are removed from subjects and the alignment of tumor with relation to the field of the main magnet is noted.
- cell sodium is known as a function of cell morphology from flow cytometry studies, then planimetry and digital reconstruction of the tumor from histological sections can be used to estimate the 3-dimensional sodium data for comparison with the weighted Na-MR images. This is because equivalent identification of cell morphology can be made for flow cytometry and histology. That is , similar techniques of DNA staining, fluorescent endlabelling, and annexin binding can be used in both modalities.
- Chemotherapy as monitored with Na-MRI Following acquisition of control images, antineoplastics are administered. Mice are reanesthetized and an additional set of MRI images acquired.
- mice Prior to recovery from the final imaging session, mice are sacrificed, tumors recovered and sectioned. Sections are prepared as follows: a. Histology - sections are flash frozen or fixed in 10% formalin for later histology and immunohistochemistry as required. In si tu fluorescent endlabelling is performed on immunoblanks prepared from fixed tumors by the Cancer Center Molecular Pathology Core. 46 b. Cultured or fixed for flow cytometry - sections are washed in PBS, treated with collagenase, cultured or fixed for later flow cytometry study. Adequacy of in vivo drug levels are assessed by comparing flow cytometry data of cells from treated tumors versus those cultured directly from commercial stocks.
- Atomic absorption spectroscopy - sections are blotted and placed in liquid nitrogen for later AAS analysis.
- AAS studies 20 minutes prior to sacrifice, a 100 ⁇ L injection of 80 mM potassium cobaltic EDTA in saline is injected as an extracellular marker into a femoral artery (83, 96). Due to potential problems with inadequate vasculature perfusion, these experiments are performed on small tumors (5-7 mm diameter) where gross evidence of necrosis is not seen, either from histology or in the images . Treated tumors are compared with non-treated controls.
- cells are dissociated from sections of tumor (-0.5 gm ea . ) removed from treated and untreated mice. After culturing, they will be subjected to MTT or FACS to look for altered drug response due to in vivo mutations, gene amplification, or altered MDR expression.
- Portions of images means single pixels, groups of pixels determined by categorical groupings or by analysis of local contrast or noise, or regions of interest (defined as 47 collections of pixels with definable boundaries based on properties of variations in the image intensity) .
- Co-registered images are images using different pulse sequences, but where a pixel to pixel mapping between images identify equivalent physical locations.
- experimental animal imaging two images are co-registered if the images are taken in sequence without the animal moving or the coil positions being changed. Tumor boundary definition will be accomplished with co-registered proton images which show structure. Proton and sodium images can be obtained without changing coils if the coils are doubly tuned. ( Figure 8)
- ⁇ I[a,b] integrated image intensity - sum of all pixel intensities over the region defined by the argument 'a' using a pulse sequence defined by the argument ' b 1
- #px as the number of pixels in the regions defined by ' a ' .
- V j _ All volume within cells and within tumor boundary or defined region.
- V Q All volume outside cells but within tumor boundary or defined region.
- C 0 average extracellular sodium concentration (units of Na moles of nuclei per extracellular volume in liters).
- C Q 145 millimoles per liter (mMol/L)
- plasma sodium levels could be measured for each patient prior to imaging and used for this value.
- a series of phantoms would be available having been tested and characterized. They would contain values of sodium concentration over the normal expected range varying in steps of 1 mMol/L.
- phantoms Using varying concentrations of Ficoll or agarose, phantoms would also have varying T ] _ values over an expected range in steps of 1 millisecond (for example, but not limited to 35 msec to 55 msec) . If possible T2 values could also be matched between the phantom and the extracellular fluid, but alternatively they could be measured and difference corrected for by the equation just below for £. Since echo times can be kept short compared to T2, this correction may be small.
- T ] _, T2, T R , T E , T ⁇ which are respectively the longitudinal relaxation times 1 and 2, the repetition and echo times, and the time to the inversion pulse.
- T X#I and T x>0 We refer to the composite intracellular T x as T 1(1 and the composite extracellular T : as T lf0 .
- Quantitation Equation 1 Quantitative estimation of average IR(T ⁇ ) image intensity as a function of relaxation times, inversion times, relative intracellular volume, and intracellular sodium concentration.
- Quantitation Equation 2 Quantitative estimation of average single quantum image intensity as a function of relaxation times, inversion times, relative intracellular volume, and intracellular sodium concentration.
- dl/dT x C 0 A (l-(V i /V T )) f[ ⁇ l#0, X/min ]/dT x + C ⁇ A
- Flow cytometry was used to examine a second, presumably an earlier event in the apoptotic cascade, reorientation of phosphatidylserine within the cell membrane (Fig. 3.B.).
- Live cells were exposed to an annexin V / FITC conjugated antibody.
- annexin labeling cells were cultured for 1 day, treated, then lifted off the culture plate using PBS plus EDTA and exposed to Annexin V / FITC conjugated antibody. Trypsin - which cleaves the antibody binding site - was avoided. Cells were then examined with flow cytometry as per Kit instructions (product #AG604, Chemicon International. (93) Enhanced fluorescence indicates early cellular commitment to the apoptotic cascade.
- annexin V response to 10 ug/ml VP-16 etoposide (10 ⁇ g/ml) was pronounced at 24 and apparent at 17 hrs, but not at 5 hrs.
- Up to 2/3 of the live cells (propidium iodide negative) were in the well defined annexin V positive peak (top insert, Fig. 3.B.) .
- the taxotere response was much less pronounced at 24 hrs (10 nM) , but was substantially greater at higher drug concentrations (10.0 ⁇ M) or at later times (e.g. 48 hrs), where a response comparable to VP16 etoposide occurred. From dose response curves with annexin V fluorescent antibody, we determined that our standard doses were approximately 3 x Kd measured at 24 hrs for VP-16 and 48 hrs for taxotere .
- Typical human doses per square meter for taxotere and for VP-16 etoposide are respectively 60-100 mg and 100 mg .
- Tumors were removed from animals following the final imaging session, and examined histologically to confirm their cellular 57 constituents. Tumors were weighed, measured, preserved in 10% formalin, sectioned, and stained with H&E. Most tumors were elliptical in shape and were encapsulated by an endothelial membrane.
- Beneath an endothelial sheath were cells characterized as high grade carcinoma. Elliptical dimensions of major and minor axes were in the ranges of 1.0-1.5 and 0.5-0.8. Quantitative immunofluorescent studies are required to determine the differential response of chemotherapy versus ambient necrosis. Tumor weights ranged from 230 mg to 1.5 gms . This result is best illustrated visually by showing images from a particular experiment where, in addition to the intensity change, there was a clear spatial broadening of the tumor on the IR image. This is illustrated with two adjacent IR slices from image sets prior to (panels A & B) and subsequent to (panels C & D) taxotere administration (Fig. 5a). Preliminary studies show end labeling fluorescence is brightest in regions suggesting imaging results (5b).
- the in vivo injection doses were picked to be comparable to human clinical doses, and were at the high end of the maximum tolerable dose (MTD) range for nude mice. From clinical studies (9B) of plasma levels following human single loading doses of taxotere, peak values were about 5 ⁇ Mol/L, were in excess of 50 nMol/L for the first 9.6 hrs, and in excess of 10 nMol/L for the first 25 hrs. We have shown that exposure to 10 nMol/L in tissue culture resulted by 6 hrs in significant ionic elevations ( [NaJ , [CaJ ) , which persisted for at least 24 hrs.
- Antineoplastics can change cell cycle distribution often leading to apoptosis, and both changes in cell cycle phase and apoptosis alters [NaJ (21) .
- Antineoplastics affect various cellular targets which may alter ion activity, including destruction of actin filaments, microtubules, and suppression of protein synthesis and metabolism.
- antineoplastics colchicine and lonidamine both increase [CaJ and alter its subcellular handling (9, 14).
- VP-16 etoposide is reported to elevate [CaJ and [NaJ , lowers pHi, and decreases [KJ (7) in L cells.
- Both lonidamine and VP-16 are reported to cause a net reduction of total cellular monovalent cations, where K+ loss exceeds Na+ gain (7) .
- both Ca++ and H+ levels within cells are controlled by exchangers coupled to the transmembrane Na+ 59 gradient (48) ; and H+ and Ca+, have both been linked to apoptotis through pHi and [CaJ dependent endonucleases, effects on cellular Ca++ buffering and destabilization of the cytoskeleton (21, 98) .
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AU2003243236A1 (en) * | 2002-05-15 | 2003-12-02 | Yeda Research And Development Co., Ltd. | Method and apparatus for quantitatively evaluating a kidney |
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US7042219B2 (en) * | 2004-08-12 | 2006-05-09 | Esaote S.P.A. | Method for determining the condition of an object by magnetic resonance imaging |
US7289840B2 (en) | 2004-09-22 | 2007-10-30 | Receptomon, Llc | Method for monitoring early treatment response |
US7622102B2 (en) * | 2005-02-08 | 2009-11-24 | Receptomon, Llc | Method for monitoring early treatment response |
US8131337B2 (en) * | 2005-04-05 | 2012-03-06 | Receptomon, Llc | Method for monitoring early treatment response |
US7330746B2 (en) * | 2005-06-07 | 2008-02-12 | Chem Image Corporation | Non-invasive biochemical analysis |
US7330747B2 (en) * | 2005-06-07 | 2008-02-12 | Chemimage Corporation | Invasive chemometry |
US8175366B2 (en) * | 2006-10-17 | 2012-05-08 | Yeda Research & Development Co. Ltd. | Method for obtaining spatial images through MRI and processing the resulting spatial images and product |
WO2008127692A1 (en) * | 2007-04-11 | 2008-10-23 | The Trustees Of The University Of Pennsylvania | Magnetic resonance imaging for diagnostic mapping of tissues |
RU2541175C2 (en) | 2009-06-30 | 2015-02-10 | Конинклейке Филипс Электроникс Н.В. | Quantitative analysis of perfusion |
US9075122B2 (en) * | 2009-11-06 | 2015-07-07 | New York University | Method, system and computer-accessible medium for providing multiple-quantum-filtered imaging |
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US11071470B2 (en) | 2014-04-22 | 2021-07-27 | University of Pittsburgh—Of the Commonvvealth System of Higher Education | Method and system for monitoring a tissue parameter such as proteoglycan content by magnetic resonance imaging |
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