MXPA00002376A - Imaging agents for early detection and monitoring of cardiovascular plaque - Google Patents

Abstract

The invention provides imaging agents comprising a label in association with a plaque specific targeting molecule. Methods for using the imaging agents to diagnose or monitor plaque formation and growth and kits containing the cardiovascular agents or components suitable for production of the imaging agents are also provided.

Description

AGENTS TRAINERS OF IMAGES FOR TIMELY DETECTION AND MONITORING OF CARDIOVASCULAR PLATE The present invention is in the field of nuclear medicine. More specifically, the invention relates to the formation of images of plaque formation in cardiovascular tissue.

BACKGROUND OF THE INVENTION It is estimated that, in the United States, more than 1.5 million myocardial infarcts occur annually, and at least 500,000 infarctions result in death, usually sudden. (American Heart Association, Heart and Stroke Facts, Dallas, Tex: American Heart Association National Center, 1992). In accordance with the above, myocardial infarction is the most frequent cause of mortality in the United States; and in most Western countries (Coopers, ES, Prevention: The Key to Progress, Circulation, 1993; 24: 629-632, HO- ONICA Project, Myocardial Infaction and Coronary Deaths in the World Health Organization, Monica Project; Registration Procedures , Event Rates and Care Fatality Rates in 38 Populations From 21 Countries in Four Continents, Circulation, 1994; 90: 583-612). However, even the optimal use of thrombolytic therapy for myocardial infarction, the advance that has focused the most attention, could prevent only 25,000 deaths or 5 percent of the total, because most deaths occur in a sudden way, before any kind of treatment can be started. (Muller, JE, et al, Acute Risk Factors and Vulnerable Plaques: The Lexicon of a New Frontier, J. Am. Coil, Cardiol., 1994; 23: 809-813). In 1992, Fuster et al. (Fuster V. et al, The Pat ogenesis of Coronary Artery Disease and the Acute Coronary Syndromes, N. Engl. J. Med. 1992; 326: 242-250) classified the progress of coronary atherosclerotic disease. in five phases. Phase I is represented by a small plaque that is present in most people under 30 years of age, regardless of their country of origin, and usually progresses slowly (lesions types I to III). Phase II is represented by a plate, not necessarily very stenotic, with a high lipid content, which is very susceptible to rupture (lesions types IV and Va). The plate of phase 23 can be broken with predisposition in exchange for its geometry, and its formation of mural thrombus, and these processes by definition represent phase 3 (type I injury), with a subsequent increase in stenosis, possibly resulting in angina , or sudden ischemic death. The mural and occlusive thrombi of the plaques of phases 3 and 4, when organized by the connective tissue, can contribute to the progress of the atherosclerotic process represented by several stenotic or occlusive plaques of phase 5 (lesions types Vb and Ve). The severely stenotic plaques of phase 5, due to stasis and / or desendothelialization, can become complicated by a thrombus and / or by a rapid myoproliferative response, also leading to an occlusive plate of phase 5. It is interesting that approximately Two thirds of the coronary occlusions are the result of this last stenotic type of plaque, and they are not related to the alteration of the plaque. Unlike the rupture of lipid-rich plaques, less stenotic, leading to occlusion and subsequent infarction, or other acute coronary syndromes, this process of occlusion by late stenotic plaques tends to be silent, because the severe stenosis precedent and ischemia improve protective collateral circulation. (Fuster, V et al, The Pathogenesis of Coronary Artery Disease and the Acute Coronary Syndromes, N. Engl., J. Med. 1992; 326: 242-250; Chesebro, JH et al., Antithrombotic Therapy and Progression of Coronary Artery Disease. Circulation 1992; 86 (supplement III)). Sensitive and specific agents are needed to identify the early stages of plaque formation in a subject, whose progress can then be delayed or reduced by initiating an appropriate therapeutic regimen or change in lifestyle.

SUMMARY OF THE INVENTION In general, the invention provides imaging agents comprised of a targeting moiety and a tag, such as a radionuclide or paramagnetic contrast agent. In the preferred embodiments, the labeled imaging agents comprise a small molecule that localizes rapidly (i.e., in less than about 24 hours, more preferably in less than about 12 hours, and most preferably in less than about 6 hours), and that it is located in a selective and irreversible way at the site of a plate, and is rapidly released from other tissues. Examples of the appropriate radionuclides include: 131I, 125I, 123I, 99mTc, 18F, 68Ga, e7Ga, 72As, 89Zr, 6 Cu, 62Cu, lxlIn, 203Pb, 198Hg, 97Ru, lC and 201TI. Suitable paramagnetic contrast agents include gadolinium, cobalt, nickel, manganese, and iron. Particularly preferred paramagnetic radionuclides or contrast agents have an appropriate half-life and high spic activity. Particularly preferred targeting moieties comprise components of the processes involved in plaque formation and growth, as well as spic binding partners therewith (eg, receptors and fragments thereof, receptor ligands, and antibodies and binding fragments). thereof) . Particularly preferred targeting fractions are comprised of components of the processes involved in plaque formation and growth, as well as spic binding partners with these components (e.g., receptors and fragments thereof, receptor ligands (e.g., agonists). or receptor antagonists), and antibodies and binding fragments thereof). Examples include: (i) cells, including smooth muscle cells, leukocytes, lymphocytes (B lymphocytes and T lymphocytes), monocytes, macrophages, foam cells, platelets, erythrocytes, and polymorphonuclear cells (e.g., granulocytes and neutrophils), and cell fragments (e.g., heme) and analogs thereof (e.g., porphyrins and phthalocyanines); (ii) molecules that attract or modify cell migration, including chemotactic proteins and peptides (for example, monocyte chemotactic protein 1 (MCP-1)), and N-formyl-methionyl-leucyl-phenylalanine and other formyl peptides; colony-stimulating factors (e.g., GM-CSF and CSF-1), and receptors and antibodies thereto; and platelet factor 4; (iii) growth factors (e.g., transforming growth factors, e.g., TGF-β, endothelial growth factors (e.g.

VEGF), and growth factors that initiate smooth muscle proliferation), (iii) cell surface adhesive glycoproteins (e.g., E-selectin, VCAM-1 and VCAM1 / 8, and carbohydrates, such as 1: LC-deoxy -D-glucose and 18F-2-fluorodeoxy-D-glucose); (iv) other components of a vascular inflammatory response (for examples of complement components (eg, Cl, Clq, Clr, Cls, C2, C3, C3a, C3b, C4, C4C2, C4C2C3b, C5a, C5b, and C5a )), immunoglobulins and cytokines (eg, interleukins (eg, IL-1, (IL-la and IL-10, IL-2, IL-3, IL-6, IL-7, and IL-8)) , interferons (interferon ot, interferon?), and tumor necrosis factors (eg, TNF-a), (v) cellular sources of energy for the formation of metabolically active plaque, (vi) lipids (eg, liposomes, including liposomes coated with polyethylene glycol (PEG), cholesterol and its esters, lipoproteins (e.g., LDL, HDL, oxidized LDL), and lipid receptors, and (vii) components of the coagulation cascade (e.g., fibrin, thrombin, fibrinogen , factor VIII, factor IX, etc.) In another aspect, the invention relates to methods for manufacturing the imaging agents, in a preferred embodiment, a sea The appropriate cation is ionically or covalently associated with the address fraction by any of a variety of means. In a preferred embodiment, the association is through the incorporation of a chelating structure, such as -N2S2, -NS3, -N4, an isonitrile, a hydrazine, a HYNIC (hydrazinonicotinic acid), 2-methylthiolnicotinic acid, phosphorus, or a group containing carboxylate. In yet another aspect, the invention provides methods for imaging a subject for plaque formation and growth, which comprises administering to the subject an effective amount of an imaging agent of the invention, and detecting the concentration and spatial distribution of the agent, using an appropriate detection means, wherein a higher differential accumulation of the agent at a particular location relative to other locations within the cardiovascular tissue or of a subject, indicates plaque formation in the subject, and where a higher differential accumulation of the agent at a particular location relative to the accumulation detected at the same location in a previous image formation indicates plaque growth. In yet a further aspect, the invention provides a kit for imaging, which includes, but is not limited to, a delivery of the imaging agent or its precursor. The kit can also include at least one chelating structure and / or an auxiliary molecule, such as mannitol, gluconate, glucoheptonate, and tartrate.; and a reducing agent containing tin. Other features or advantages of the present invention will become clearer from the following detailed description and from the claims.Detailed Description of Preferred Modes For convenience, the meaning of certain terms and phrases employed in the following specification, examples, and appended claims are given below: An "antibody or fragment thereof" refers to a polyclonal or whole monoclonal antibody, or a binding fragment thereof. A "chelating structure" refers to any molecule or complex of molecules that binds both to the brand and to the address fraction. Examples include: the structure N2S2, a structure NS3, a structure N4, a structure containing isonitrile, a structure containing hydrazine, a structure containing the group HYNIC (hydrazinonicotinic acid), a structure containing acid group 2 -methytiolnicotinic, a structure containing carboxylate group, and the like. "Cardiovascular disease" or "cardiovascular injury" refers to any of a variety of diseases or injuries of the heart or the vasculature of a subject. Examples include atherosclerosis (ie, thickening and hardening of the arteries due to plaque formation), and related disorders resulting from clogged blood flow (eg, angina, cerebral ischemia, renal hypertension, ischemic heart disease, embolism), and thrombus formation (eg, deep vein thrombosis (DVT)). "Cardiovascular tissue" refers to any and all tissue comprising the cardiovascular system, including: all components of the heart, aortas, arteries, eg, coronary and carotid), veins, or components of these tissues and organs. A "precursor of an imaging agent" refers to any molecule or complex of molecules that are readily converted to the imaging agent. A "small molecule" refers to a composition having a molecular weight that is less than about 5 KD, more preferably less than about 4 KD, still more preferably less than about 3 KD, and most preferably less than about 2 KD. "Subject" refers to an animal, for example a mammal, particularly a human being. A "targeting fraction or precursor thereof" is any molecule or biological entity that targets cardiovascular tissue or thrombi, or any molecule or biological entity that readily converts to that molecule or biological entity. "Thrombus" refers to a blood clot formed inside a blood vessel from a plaque, and which remains attached to its place of origin. "Vascular inflammation" refers to vascular tissue damage in a subject, which may result from a number of causes (e.g., microbial infection, autoimmune processes, any injury or trauma, etc.). Regardless of the cause, the vascular inflammatory response consists of a complicated set of functional and cellular adjustments that involve changes in microcirculation, movement of fluids, proliferation of smooth muscle cells, generation of foam cells, and influx and activation of inflammatory cells . The present invention provides novel imaging agents that are comprised of a directional fraction and a mark. These novel imaging agents accumulate specifically on actively active or actively growing plates, and therefore, are useful for detecting or monitoring plaque formation. Particularly preferred targeting fractions are comprised of components of the processes involved in plaque formation and growth, as well as the binding partners specific to these components (eg, receptors and fragments thereof, receptor ligands (eg, agonists). or receptor antagonists), and antibodies and binding fragments thereof). Examples include: (i) cells, including smooth muscle cells, leukocytes, lymphocytes (B lymphocytes and T lymphocytes), monocytes, macrophages, foam cells, platelets, erythrocytes, and polymorphonuclear cells (e.g., granulocytes and neutrophils), and cell fragments and analogs thereof (for example, porphyrins, such as heme and phthalocyanines); (ii) molecules that attract or modify cell migration, including chemotactic proteins and peptides (e.g., monocyte chemotactic protein 1 (MCP-1)), and N-formyl-methionyl-leucyl-phenylalanine (see U.S. Pat. United States No. 5,7921,444), other formyl peptides; colony-stimulating factors (e.g., GM-CSF (see U.S. Patent Nos. 5,229,496 and 4,879,227), and CSF-1 (see U.S. Patent Nos. 4,847,201; 4,868,119 and 4,929,700), and receptors and antibodies thereto; and platelet factor 4; (iii) growth factors (e.g., transforming growth factors, e.g. TGF-β, endothelial growth factors (e.g., VEGF), and growth factors that initiate smooth muscle proliferation), (iii) cell surface adhesive glycoproteins (e.g., E-selectin, VCAM-1 and VCAMlβ (see U.S. Patent Number 5,272,263), and ICAM-1 (see Rosenfeld , ME et al., Cellularity of Atherosclerotic Lesions Car. Art. Dis. 1994; 5: 189-197; Navab, M. et al., Monocyte Adhesion and Transmigration in Atherosclerosis, Cor Art. Dis. 1994; 5: 198-204) and other binding molecules (See, for example, Kim, JA et al., Partial Characterization of Leukocyte Binding Molecules on Endothelial Cells Induced by Minimally Oxidized LDL Arterio. Thromb. 1994; 24: 427-433)); and carbohydrates (such as 1: LC-deoxy-D-glucose and 18F-2-fluorodeoxy-D-glucose); (iv) other components of a vascular inflammatory response (for examples, the complement components (eg Cl, Clq, Clr, Cls, C2, C3, C3a, C3b, C4, C4C2, C4C2C3b, C5a, C5b, and C5a), immunoglobulins and cytokines (e.g., interleukins, (e.g., IL-1, (IL-la (see U.S. Patent Number 4,762,914) and IL-lß (See Patent of the United States of America Number 4,766,061), IL-2 (see U.S. Pat.

North America Numbers 5,037,644; 4,939,093; 4,604,377; and 4,518,584); IL-3; IL-4 (see U.S. Patent Number 5,017,691); IL-6; IL-7; and IL-8), interferons (interferon alpha, interferon?), and tumor necrosis factors (e.g., TNF-a); (v) cellular sources of energy for the formation of metabolically active plaque; (vi) lipids (e.g., liposomes, including liposomes coated with polyethylene glycol (PEG), cholesterol and its esters, lipoproteins (e.g., LDL, HDL, oxidized LDL), and lipid receptors, and (vii) components of the cascade of coagulation (for example, fibrin, thrombin, fibrinogen, factor VIII, factor IX, etc.).

According to the invention, the steering molecule is in association with (in spatial proximity to) the mark. The spatial proximity between the targeting molecule and the tag can be affected in any way that retains the specificity of the targeting molecule for its target tissue. For example, the spatial proximity between the label and the targeting molecule can be affected by a covalent or non-covalent chemical bond. This chemical bond can be effected through a chelating substance and / or an auxiliary molecule, such as mannitol, gluconate, glucoheptonate, tartrate, and the like. Alternatively, the spatial proximity between the tag and the targeting molecule can be effected by incorporating the tag and the targeting molecule into a mycelium or liposome, so that the affinity of the targeting molecule is maintained for your target tissue. The spatial proximity between the label and the targeting molecule can also be effected by attaching the label and the targeting molecule to a matrix, such as a microsphere, liposome, or mycelium. The imaging agents described above may contain any marking according to the invention. Radionuclides provide highly specific and sensitive markers, which can then be detected, using positron emission tomography (PET), or single-photon emission computed tomography (SPECT) imaging. More preferably, the imaging agent of the invention contains a radionuclide selected from the group consisting of 131I, 125I, 123I, 99mTc, 18F, 68Ga, 67Ga, 72As, 89Zr, 64Cu, 62Cu, ^ In, 203Pb, 198Hg, "C, 97Ru, and 201TI, or a paramagnetic contrast agent, such as gadolinium, cobalt, nickel, manganese, and iron.These labels can be incorporated into the imaging agent by covalently linking directly with an atom. of the targeting molecule, or the tag can be associated in a non-covalent or covalent manner with the targeting molecule through a chelating structure, or through an auxiliary molecule, such as mannitol, gluconate, glucoheptonate, tartrate, and the like When a chelant structure is used to provide spatial proximity between the mark and the direction molecule, the chelating structure can be directly associated with the direction molecule, or it can be associated with the molecule. a direction through an auxiliary molecule, such as mannitol, glycolate, glucoheptonate, tartrate, and the like. Any suitable chelating structure can be used to provide spatial proximity between the radionuclide and the agent targeting molecule through covalent or non-covalent association. Many of these chelating structures are known in the art. Preferably, the chelating structure is a N2S2 structure, an NS3 structure, a N4 structure, a structure containing isonitrile, a structure containing hydrazine, a structure containing HYNIC group (hydrazinonicotinic acid), a structure containing acid group, and -methythiolnicotinic, a structure containing carboxylate group and the like. In some cases, chelation can be achieved without including a separate chelating structure, because the radionuclide is directly chelated in the atoms in the directional fraction, for example in the oxygen atoms of different fractions. The chelating structure, the auxiliary molecule, or the radionuclide, can be placed in spatial proximity to any position of the targeting molecule, which does not interfere with the interaction of the targeting molecule with its target site in the cardiovascular tissue. In accordance with the foregoing, the chelating structure, the auxiliary molecule, or the radionuclide, may be covalently or non-covalently associated with any fraction of the targeting molecule, with the exception of the binding moiety of the receptor. The radionuclides can be placed in spatial proximity to the targeting molecule using known methods that effect or optimize the chelation, association, or binding of the specific radionuclide to the ligands. For example, when 123I is the radionuclide, the imaging agent can be labeled according to known radioiodination procedures, such as direct radioiodination with chloramine T, radioiodination exchange for a halogen or an organometallic group, and the like. When the radionuclide is 99mTc, the imaging agent can be labeled using any suitable method to bind 99mTc to a ligand molecule. Preferably, when the radionuclide is 99mTc, an auxiliary molecule such as mannitol, gluconate, glucoheptonate, or tartrate is included in the marker reaction mixture, with or without a chelating structure. More preferably, 99mTc is placed in spatial proximity to the targeting molecule, by reducing 99mTc 02 with tin in the presence of mannitol and the targeting molecule. Other reducing agents, including tin tartrate or non-tin reducing agents, such as sodium dithionite, can also be used to make the cardiovascular imaging agent of the invention. In general, the methodologies of marking vary with the choice of the radionuclide, the fraction to be marked, and the clinical condition under investigation. Labeling methods using 99mTc and 11: LIn are described, for example, in Peters A.M. and collaborators, Lancet 2: 946-949 (1986); Srivastava, S.C. and collaborators, Semin. Nucí Med. 14 (2) -.68-82 (1984); Sinn, H. and collaborators, Nucí. Med. (Stuttgart) 13: 180 (1984); McAfee, J.G. and collaborators, J.? ucl. Med. 17: 480-487, 1976; McAfee, J.G. and collaborators, J.? ucl. Med. 17: 480-487, 1976; Welch, M.J. and collaborators, J.? ucl. Med. 18: 558-562, 1977; McAfee, J.G. and collaborators, Semin. Nucí Med. 14 (2): 83, 1984; Thakur, M.L. and collaborators, Semin. Nucí Med. 14 (2): 107, 1984; Danpure, H.J. and collaborators, Br. J. Radiol. , 54: 597-601, 1981; Danpure, H.J. and collaborators, Br. J. Radiol. 55: 247-249, 1982; Peters, A.M. and collaborators, J. Nucí. Med. 24: 39-44, 1982; Gunter, K.P. et al., Radiology 149: 563-566, 1983; and Thakur, M.L. and collaborators, J. Nucí. Med. 26: 518-523, 1985. After the labeling reaction is completed, the reaction mixture can optionally be purified using one or more chromatography steps, such as Sep Pack, or high performance liquid chromatography (HPLC). ). Any suitable high performance liquid chromatography system can be used, if a purification step is performed, and the performance of the cardiovascular imaging agent obtained from the high performance liquid chromatography step can be optimized by varying the parameters of the high performance liquid chromatography system, as is known in the art. Any parameter of high performance liquid chromatography can be varied to optimize the performance of the cardiovascular imaging agent of the invention. For example, the pH can be varied, for example it can be raised to decrease the elution time of the peak corresponding to the cardiovascular imaging agent of the invention.

The invention as incorporated in an imaging kit comprises one or more of the imaging agents described above, in combination with a pharmaceutically acceptable carrier, such as human serum albumin. Human serum albumin for use in the kit of the invention, can be made in any way, for example, through purification of human serum protein, or through recombinant expression of a vector containing a gene encoding the human serum albumin. Other substances can also be used as vehicles in accordance with this embodiment of the invention, for example, detergents, diluted alcohols, carbohydrates, auxiliary molecules, and the like. The cassette of the invention, of course, may also contain other articles that may facilitate its use, such as syringes, instructions, reaction flasks, and the like. In one embodiment, a kit according to the invention contains from about 1 to about 30 mCi of the radionuclide-labeled cardiovascular imaging agent described above, in combination with a pharmaceutically acceptable carrier. The cardiovascular imaging agent and the vehicle can be provided in solution or in a lyophilized form. When the cardiovascular imaging agent and the carrier of the kit are in a lyophilized form, the kit may optionally contain a sterile and physiologically acceptable reconstitution medium, such as water, serum, regulated serum, and the like. In another embodiment, the kit of the invention may contain the non-labeled targeting molecule, which has been combined in a covalent or non-covalent manner with a chelating agent; an auxiliary molecule, such as mannitol, gluconate, glucoheptonate, tartrate, and the like; and a reducing agent, such as SnCl2 or tin tartrate. The unlabeled targeting molecule / chelating agent and the auxiliary molecule may be present as separate components of the kit, or may be combined in a one-component kit. The unlabeled targeting molecule / chelating agent, the auxiliary molecule, and the reducing agent, can be provided in solution or in a lyophilized form, and these components of the kit of the invention optionally can contain stabilizers, such as NaCl, silicate, regulators of phosphate, ascorbic acid, gentisic acid, and the like. In this embodiment, additional stabilization of the cassette components can be provided, for example, by providing the reducing agent in an oxidation-resistant form. The determination and optimization of these stabilizers, and the stabilization methods, are well within the level of experience in the field. When the unlabelled targeting molecule / chelating agent of this embodiment is in a lyophilized form, the kit may optionally contain a sterile and physiologically acceptable reconstitution medium, such as water, serum, regulated serum, and the like. The amounts of unlabeled direction molecule / chelating agent, auxiliary molecule, and reducing agent in this embodiment can be optimized according to the methods for making the cardiovascular imaging agent stipulated above. Radionuclides, including, but not limited to, 99mTc, for example, obtained from a commercially available 99Mo / 99mTc generator, or commercially available 123I, may be combined with the unlabeled targeting molecule / chelating agent and the reducing agent, for a sufficient period of time, and at a sufficient temperature, to chelate the radionuclide to the targeting molecule / chelating agent, and in this manner, the formed imaging agent is injected into the patient. The cardiovascular imaging agents of the invention can be used in accordance with the methods of the invention by those skilled in the art., for example, by specialists in nuclear medicine, to form the image of the plaque in the cardiovascular system of a subject. The images are generated by virtue of the differences in the spatial distribution with the image-forming agents that accumulate in the different tissues and organs of the subject. The spatial distribution of the accumulated imaging agent can be measured using any suitable means, for example, a gamma camera, a PET apparatus, a SPECT apparatus, and the like. Some cardiovascular lesions may be evident when a less intense spot appears within the image, indicating the presence of tissue, where a lower concentration of imaging agent accumulates relative to the concentration of imaging agent that accumulates in the the surrounding cardiovascular tissue. Alternatively, a cardiovascular lesion could be detected as a more intense spot within the image, indicating a region of better concentration of the imaging agent at the site of the lesion in relation to the concentration of the agent that accumulates in the lesion. surrounding cardiovascular tissue. Thrombi and embolisms are examples of cardiovascular lesions that accumulate higher concentrations of the imaging agents of the invention. The accumulation of lower or higher amounts of the imaging agent at the site of a lesion can be detected visually, by inspection of the image of the cardiovascular tissue. Alternatively, the extent of the accumulation of the imaging agent can be quantified using known methods for quantifying radioactive emissions. A particularly useful imaging approach employs more than one imaging agent to perform simultaneous studies. For example, simultaneous studies of perfusion and metabolic function would allow us to study the coupling and uncoupling of the flow of metabolism, thus facilitating the determinations of tissue viability after cardiac injury. These determinations are useful to diagnose cardiac ischemia, cardiomyopathy, tissue viability, heart in hibernation, and other abnormalities of the heart. An effective amount of an imaging agent comprising at least one targeting molecule and a tag (eg, from about 1 to about 50 mCi of a radionuclide), may be combined with a pharmaceutically acceptable carrier for use in training studies. of pictures. According to the invention, "an effective amount" of the imaging agent of the invention is defined as an amount sufficient to produce an acceptable image using equipment that is available for clinical use. An effective amount of the imaging agent of the invention can be administered in more than one injection. The effective amounts of the image forming agent of the invention will vary according to factors such as the degree of susceptibility of the individual, the age, sex, and weight of the individual, the idiosyncratic responses of the individual, dosimetry. The effective amounts of the image forming agent of the invention will also vary according to the instrument and factors related to the film. The optimization of these factors is well within the level of experience in the field. In general, the effective amount will be on the scale from about 0.1 to about 10 milligrams per injection, and from about 5 to about 100 milligrams orally for use with MRI. As used herein, "pharmaceutically acceptable carrier" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic agents, absorption delaying agents, and the like. The formulation used in the present invention may also contain stabilizers, preservatives, pH regulators, antioxidants, and other additives known to those skilled in the art. The use of these media and agents for pharmaceutically active substances is well known in the art. Complementary active compounds can also be incorporated into the imaging agent of the invention. The imaging agent of the invention can be further administered in an individual in a suitable diluent or auxiliary, it can be co-administered with enzyme inhibitors or in an appropriate vehicle, such as human serum albumin or liposomes. Pharmaceutically acceptable diluents include sterile serum and other aqueous buffer solutions. Auxiliaries contemplated herein include resorcinols, non-ionic surfactants such as polyoxyethylene oleyl ether and N-hexadecyl polyethylene ether. Enzyme inhibitors include pancreatic trypsin inhibitor, diethyl pyrocarbonate, and trasilol. Liposome inhibitors include CGF emulsions of water in oil in water, as well as conventional liposomes (Strejan et al., J. Neuroimmunol 7:27 [1984]). The present imaging agents can be administered to a subject according to any means that facilitates the accumulation of the agent in a cardiovascular system of the subject. Preferably, the imaging agent of the invention is administered by arterial or venous injection, and has been formulated as a sterile, pyrogen-free, parenterally acceptable aqueous solution. The preparation of these parenterally acceptable solutions, with due regard to pH, and their tonicity, stability, and the like, is within the field of experience. A preferred formulation for intravenous injection should contain, in addition to the cardiovascular imaging agent, an isotonic vehicle, such as Sodium Chloride Injection, Ringer's Injection, Dextrose Injection, Dextrose Injection and Sodium Chloride, Lactated Ringer's Injection , or another vehicle known in the art. The amount of imaging agent used for diagnostic purposes, and the duration of the imaging study, will depend on the nature and severity of the condition being treated, on the nature of the therapeutic treatments the patient has undergone, and the idiosyncratic responses of the patient. Finally, the attending physician will decide the amount of imaging agent that should be administered to each individual patient, and the duration of the imaging study. The present invention is further illustrated by the following examples, which are not to be construed as limiting in any way. The content of all cited references (including literature references, issued patents, published patent applications), as cited throughout this application, is expressly incorporated herein by reference.

Example; Preparation of the Radiolabeled Chemoattractant Peptide For-MLF For-MLF is a bacterial product that initiates the chemotaxis of leukocytes by its binding to high-affinity receptors on the membranes of white blood cells (Showell et al., J. Exp. Med. 143 : 1154-1169 [1976], Schiffmann et al., Proc Nati Acad Sci USA 72: 1059-1062 [1975], Williams et al., Proc Nati Acad Sci 74: 1204-1208 [1977]). These receptors are present in both polymorphonuclear leukocytes and mononuclear phagocytes. Due to the very small size of For-MLF (MW 437), its molecular structure can be easily manipulated to design an optimal imaging agent. The labeled chemotactic peptide can be synthesized and purified by the techniques described in Babich et al., J Nucí Med 34: 1964-1974 (1993). Dimethylformamide (DMF) (2 milliliters) and 60 microliters of di-isopropylethylamine are added to 186 milligrams of N-For-Met-Leu-Phe-diaminohexylamide, followed by 154 milligrams of succinimidyl-6-t-BOC-hydrazinopyridin-3 acid. -carboxylic acid in 1 milliliter of dimethylformamide. The mixture becomes yellow, and the peptide dissolves within a short time. After 2 hours, ether is added to the reaction mixture, and the top layer is discarded. Water is added to the oily residue causing a solid to form. The solid is washed with 5 percent sodium bicarbonate, water, and ethyl acetate, and the yield is determined. The t-BOC protecting group is removed by stirring the crude product with 5 milliliters of trifluoroacetic acid (TFA) containing 0.1 milliliter of p-cresol for 15 minutes at 20 ° C. A prolonged treatment with trifluoroacetic acid results in higher levels of a secondary product. The trifluoroacetic acid is removed by rotary evaporation, and ether is added to the residue to precipitate the deprotected peptide. The product is purified by reverse phase high performance liquid chromatography on a Whatman ODS-3 column of 2.5 x 50 centimeters, and eluted with a gradient of acetonitrile in 0.1 percent trifluoroacetic acid. The fractions containing the major component are combined, and the solvent is removed to give the desired product. Techteinium-99m pertechnetate (99Mo / 99Tc generator) and stannous glucoheptonate (Glucosan) are obtained from New England Nuclear (Boston, MA). Technetium-99m glucoheptonate is used to provide the Te (V) oxo species necessary for the radiolabelling of the hydrazinonicotinamide-conjugated peptides. Approximately 2.5 milliliters of 99mTc pertechnetate in 0.9 percent NaCl is added to the freeze-dried case. The final radioactive concentration is 5-10 mCi / milliliter, and the radiochemical purity of the product is determined by flash thin layer silica gel chromatography (ITLC-sg) using both acetone and 0.9 percent NaCl as solvents in mobile phase. Approximately 0.2 milligrams of peptide are dissolved in 50 microliters of dimethyl sulfoxide, and the solution is diluted to a final concentration of 0.1 milligram / milliliter with 0.1M acetate buffer, pH 5.2. The peptide solution (0.5 milliliters) is placed in a clean glass jar, and 0.5 milliliters of 99mTc glucoheptonate are added. The mixture is vortexed briefly and allowed to stand at room temperature for 1 hour. The radiochemical purity is determined by ITLC-sg in three solvent systems: acetone, 0.9 percent NaCl, and acetone and water (9: 1).

Equivalents Those skilled in the art will recognize, or may assert, using no more than routine experimentation, many equivalents of the specific embodiments of the invention described herein. It is intended that these equivalents be encompassed by the following claims.

Claims (22)

1. t T 29 CLAIMS 1. A cardiovascular imaging agent, which comprises a radionuclide, wherein the radionuclide is associated with a targeting moiety, this targeting moiety comprising a specific infection agent.
2. 2. The agent of claim 1, wherein the address fraction is linked to characteristic fractions of an infection process.
3. 3. The agent of claim 2, wherein the infection process is inflammation.
4. 4. The agent of claim 1, wherein the address fraction is a leukocyte.
5. 5. The agent of claim 1, wherein the targeting moiety is a protein.
6. 6. The agent of claim 5, wherein the protein is a chemotactic peptide.
7. 7. The agent of claim 6, wherein the chemotactic peptide is For-MLF.
8. 8. The agent of claim 5, wherein the protein is an antibody or fragment thereof.
9. 9. The agent of claim 1, wherein the radionuclide is selected from the group consisting of 123I, 99mTc, 18F, 68Ga, 62CU, and X11ln.
10. The agent of claim 9, wherein the agent comprises the product of combining the targeting moiety or the precursor thereof with a chelating compound, which chelates this radionuclide.
11. The agent of claim 10, wherein the chelating compound is selected from the group consisting of an -N2S2 structure, an NS3-structure, an N4-structure, an isonitrile, a hydrazine, a structure containing HYNIC group , a structure containing 2-methylthiolnicotinic acid group, a carboxylate group-containing structure, an amino carboxylate, and a phenolate.
12. 12. The agent of claim 11, wherein the radionuclide is 99mTc.
13. 13. A method for imaging cardiovascular tissue in a mammal, which comprises administering to the mammal the agent of claim 1.
14. The method of claim 13, wherein the method detects a cardiovascular injury in a mammal, comprising method the steps of administering to the mammal said agent, detecting the spatial distribution of the accumulated agent in the cardiovascular system of the mammal, wherein a detected accumulation of the agent in a region that is different from the accumulation detected of this agent in other regions, indicates a injury.
15. 15. The method of claim 14, wherein the cardiovascular lesion is an atherosclerotic lesion.
16. 16. A method for imaging a thrombus in a mammal, which comprises administering to the mammal the imaging agent of claim 1.
17. 17. A kit for forming cardiovascular images, which comprises a delivery of the imaging agent, or a precursor of the imaging agent of claim 1.
18. 18. The kit of claim 17, which further comprises at least one chelating agent, each chelating agent comprising an auxiliary molecule selected from the group consisting of mannitol, gluconate. , glucoheptonate, and tartrate; and a reducing agent.
19. 19. The kit of claim 18, wherein the reducing agent contains tin.
20. The kit of claim 18, wherein the radionuclide of the imaging agent is selected from the group consisting of 123I, 99mTc, 18F, 68Ga, 62CU, and ^ In.
21. The kit of claim 20, wherein the chelating agents are selected from the group consisting of an -N2S2 structure, an NS3-structure, an N4-structure, an isonitrile, a hydrazine, a structure containing HYNIC group , a structure containing a 2-methylthiolnicotinic acid group, a carboxylate group-containing structure, an amino carboxylate, and an amino phenolate.
22. 22. The kit of claim 21, wherein the radionuclide is 99mTc.