WO2025160126A1 - Method and system for radiation-free assessment of coronary and skeletal muscle microvascular function using in-situ administration of vasoactive agents - Google Patents

Abstract

A method of performing rapid, minimally invasive MRI-based measurements of a biomarkers in an anatomy of a subject, comprising: using an interventional MRI-compatible guidewire and catheter; intravenously infusing an intravascular MRI contrast agent into the subject; guiding the guidewire into a region of interest in the anatomy of the subject; inserting the catheter over the guidewire until the catheter reaches the region of interest; removing the guidewire; acquiring post-infusion baseline myocardial T1 maps of the region of interest; performing intracardiac infusion of a vasoactive agent into the region of interest using the catheter for a first time period; acquiring "stress" myocardial T1 maps of the region of interest during the intracardiac infusion of the vasoactive agent; and comparing the baseline myocardial T1 maps to the "stress" myocardial T1 maps to measure the biomarker.

Description

METHOD AND SYSTEM FOR RADIATION-FREE ASSESSMENT OF CORONARY AND SKELETAL MUSCLE MICRO VASCULAR FUNCTION USING IN-SITU ADMINISTRATION OF VASOACTIVE AGENTS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 63/623,397 entitled “METHOD AND SYSTEM FOR RADIATION-FREE ASSESSMENT OF CORONARY AND SKELETAL MUSCLE MICRO VASCULAR FUNCTION USING IN-SITU ADMINISTRATION OF VASOACTIVE AGENTS”, filed on January 22, 2024, the entire disclosure of which is incorporated by reference in its entirety.

STATEMENT OF GOVERNMENTAL RIGHTS

[0002] This invention was made with government support under HL153430 awarded by National Institutes of Health. The Government has certain rights in the invention.

FIELD

[0003] The present disclosure pertains to assessment of coronary and skeletal muscle microvascular functions.

BACKGROUND

[0004] The type of biomarkers needed to guide therapies related to coronary artery dysfunction or heart failure are often measured in the cardiac catheterization laboratory (cath- lab) under x-ray fluoroscopy. In addition to cost and radiation exposure for both patients and healthcare providers, these measurements require accessing individual coronary vessels (i.e., epicardial arteries) which comes with a risk of serious complications such as coronary artery perforation, dissection, etc.

[0005] Despite the cost and associated risks, cath-lab-based coronary function testing (CFT) is experiencing growing popularity in the U.S. and Europe (with large interest from device vendors) and the recent CDC approval of 4 new ICD-10 codes to recognize the diagnosis and testing for coronary function including microvascular function. This is all driven by mounting clinical evidence that CFT-based management of patients with heart disease can help guide optimal medical therapy (with available pharmaceutical agents) resulting in alleviation of chest pain (angina), higher quality of life for the patients, and better outcomes.

[0006] Still, partially due to the risks associated with intra-coronary device placement/infusion, this fluoroscopy-based diagnostic modality is limited to highly specialized medical centers run by highly experienced interventional cardiologists. [0007] Historically, the field of interventional cardiac MRI (iCMRI) has been hampered by the incompatibility of "off the shelf' devices (specifically, guidewires and catheters) with MRI both in terms of safety and visibility (to enable real-time guidance, say, of a pigtail catheter into the left ventricle from a femoral -artery access point). In the past two years, this field has undergone a revolution with the arrival of commercially available midfield and low-field MRI scanners (e.g., 0.3T from Esaote or 0.55T from Siemens) which enable the use of off-the-shelf devices (with minimal modifications to add small "MRI markers" for improved visibility) that eliminates the issue of safety /heating of devices (up to 100-fold reduction of deposited energy compared to high-field MR). This has generated a large interest from the perspective of cardiovascular device manufacturers (e.g., Cook Medical, Boston Scientific, Nano4Imaging, Medtronic, Abbott, etc.) to introduce FDA- approved guidewires and catheters in this space. SUMMARY

[0008] The present disclosure provides a method of performing rapid, minimally invasive MRI-based measurements of a biomarkers in an anatomy of a subject. The method includes: intravenously infusing an intravascular MRI contrast agent into the subject; guiding a guidewire into a region of interest in the anatomy of the subject; inserting a catheter over the guidewire until the catheter reaches the region of interest; removing the guidewire; acquiring post-infusion baseline myocardial Ti maps of the region of interest; performing intracardiac infusion of a vasoactive agent into the region of interest using the catheter for a first time period; acquiring stress myocardial Ti maps of the region of interest during the intracardiac infusion of the vasoactive agent; and comparing the baseline myocardial Ti maps to the stress myocardial Ti maps to measure the biomarker. In one embodiment, the intravascular MRI contrast agent is Ferumoxytol. In another embodiment, the vasoactive agent is adenosine. In yet another embodiment, each of the guidewire and the catheter comprise a MR marker configured to create negative contrast on an MRI scan. The MR markers are placed on a tip of the catheter and guidewire.

[0009] In another embodiment of the method of the present disclosure, the baseline myocardial Ti map is of the subject while at rest. In another embodiment, the biomarker is ischemia. In yet another embodiment, the area of interest is a left ventricle of a heart of the subject.

[0010] The present disclosure provides an MRI-guided diagnostic device configured to measure a biomarker in an anatomy of a patient. The MRI-guided diagnostic device includes: a guidewire configured to be inserted into an artery connected to a region of interest; and a catheter configured to advance along the guidewire into the region of interest. The catheter is configured to intracardiaclly infuse a vasoactive agent into the region of interest. In one embodiment, the catheter is a pigtail catheter. In another embodiment, the region of interest is the left ventricle of a heart. In yet another embodiment, at least one of the guidewire and the catheter further comprise an MR marker configured to create negative contrast on an MRI scan. The MR markers are placed on a tip of the catheter and guidewire. In another embodiment, the vasoactive agent is adenosine. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above-mentioned and other advantages and objects of this disclosure, and the manner of attaining them, will become more apparent, and the disclosure itself will be better understood, by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0012] FIG. 1A is a side view of a 3D-printed heart phantom having a guidewire inserted into the aortic arch;

[0013] FIG. IB is a side view of the 3D-printed heart phantom of FIG. 1A having a pigtail catheter inserted into the left ventricle;

[0014] FIGS. 2A-C are side views depicting the use of a guidewire and a pigtail catheter for insertion of the pigtail catheter into the left ventricle;

[0015] FIG. 3 is a timeline diagram of an MRI protocol according to one embodiment of the present disclosure;

[0016] FIG. 4A is a myocardial T1 mapping of a heart at rest prior to hyperemia induced by intracardial infusion of adenosine;

[0017] FIG. 4B is a myocardial T1 mapping of the heart of FIG. 4A during hyperemia induced by intracardial infusion of adenosine;

[0018] FIG. 5 is a chart depicting dynamic myocardial T1 values of two regions of interest shown in FIGS. 4A and 4B before, during and after intracardial infusion of adenosine;

[0019] FIG. 6A is a graphic depiction of T1 reactivity for intracardial infusion of adenosine and intravenous infusion of adenosine; and

[0020] FIG. 6B is a graphic depiction of the percentage drop in blood pressure associated with intracardial infusion of adenosine as compared to intravenous infusion of adenosine.

[0021] Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present disclosure, the drawings are not necessarily to scale, and certain features may be exaggerated or omitted in some of the drawings in order to better illustrate and explain the present disclosure. For technical background, see the five references listed at the end of the description.

DETAILED DESCRIPTION

[0022] The present disclosure aims to solve the diagnostic problems associated with measurements taken in cath labs under x-ray fluoroscopy by enabling a rapid minimally invasive MRI-based approach to measure similar markers. Additionally, the approach described herein provides a comprehensive picture of the disease state/severity across all territories of coronary microcirculation whereas fluoroscopy-based testing typically is limited to one vessel territory (often LAD). Finally, the disclosed approach has the potential to measure biomarkers of coronary perfusion that can go beyond what is possible with intracoronary measurement of flow velocity and resistance (subendocardial reactivity, upslope, downslope, time-to-peak, peak-to-baseline) which may be more sensitive and may enable the early detection of disease.

[0023] In relation to other fully non-invasive approaches such as nuclear imaging (PET) and non-invasive MRI, the approach of the present disclosure can be performed, realistically, in a brief 10-15 minute imaging procedure which is competitive with fluoroscopy-based testing. According to the present disclosure, for the first time, real-time MRI is used to guide an MRI-compatible catheter (pigtail shape) into the left ventricle to enable in-situ (intra-cardiac) infusion of adenosine (or other vasoactive agents) with a much lower dose compared to the conventional intravenous infusion of adenosine (20-30 fold reduction in dose) over 10 seconds (10-20 fold faster than a typical 4-minute long intravenous infusion) and multi-fold lower hemodynamic change (drop in blood pressure) which helps with patient comfort.

[0024] Finally, the present disclosure leverages the emerging developments in the iCMRI marketplace by introducing a new methodology that is now commercially feasible perhaps for the first time since the invention of MRI as a clinical imaging modality 50 years ago. Although testing of coronary function and perfusion is primarily described herein, the same techniques enable testing of microvascular function in the skeletal muscle.

[0025] Myocardial stress/rest T1 reactivity, defined as the relative MRI-measured T1 change from rest to stress, has been proposed as a marker for the detection of ischemia, or lack of blood supply. Myocardial stress/rest T1 reactivity refers to the changes in the T1 relaxation time of myocardial tissue, measured using magnetic resonance imaging (MRI), under conditions of stress and rest. T1 relaxation time is a parameter that reflects the time it takes for protons in the heart tissue to relax after being excited by a magnetic field, and is influenced by the tissue’s composition and characteristics. A prolonged time for the protons in the heart tissue to relax after being excited may indicate ischemia.

[0026] A baseline T1 relaxation time of the myocardium is measured while the patient is at rest and may be depicted as a “rest T1 map.”

[0027] The T1 relaxation time is measured again after induction of stress through a pharmacological agent, such as a vasoactive agent, or through physical exercise, which increases the heart’s workload. One suitable vasoactive agent may be adenosine. The measurement taken after induction of stress may be depicted as a “stress T1 map.” Pharmacological agents may be introduced intravenously or intracardially, as described in the present disclosure. The rest T1 map and the stress T1 map may be compared to find markers for the detection of ischemia.

[0028] Invasive clinical studies have shown that intracoronary adenosine infusion has notable advantages vs. intravenous (“IV”) infusion including a faster measurement time, more than 10-fold lower dose, and improved patient comfort partially due to a smaller drop in blood pressure. Inspired by this difference between systemic (IV) and in situ (local) infusion, the present disclosure provides an iCMR paradigm for intracardiac (“IC”) infusion of adenosine to enable faster stress/rest reactivity measurement compared to IV infusion with reduced hemodynamic side effects while inducing a similar level of hyperemia, which is measured based on free-breathing, beat-to beat T1 mapping. [0029] The present disclosure provides an MRI-compatible diagnostic device configured to intracardiacally infuse a vasoactive agent into a region of interest to measure a particular biomarker. The device may comprise a guidewire and a catheter.

[0030] A needle may be inserted into a chosen artery to access the region of interest. The guidewire may be threaded into the artery and manuvered into the region of interest. The guidewire may be a flexible material comprising stainless steel, nitinol, or other surgical materials. The guidewire may have a diameter and length that allows a catheter or other device to be advanced along the guidewire into the region of interest.

[0031] Real-time CMR with modified devices (MRI-compatible sheath and guidewire as described below) may be used to navigate a guidewire, for example, from the femoral artery into the left ventricle (“LV”).

[0032] The catheter may be advanced over the guidewire into the area of interest. The catheter may be made of a flexible biocompatible material such as polyurethane, polyethylene, or other flexible polymers. Various types of catheters may be used in the diagnostic method of the present disclosure, such as a pigtail catheter.

[0033] A pigtail catheter may be then advanced over the guidewire and into the LV, and the guidewire may then be removed to enable IC infusion.

[0034] Preclinical data in pigs was acquired using the disclosed techniques as is further described below and in the figures. These data show proof of concept and feasibility of the present methodology.

[0035] The present disclosure provides a pigtail catheter suited for iCMR procedures (in terms of safety and visibility); markers on the catheter configured to create negative contrast on an MRI; a guidewire; and markers on the guidewire configured to create negative contrast on an MRI.

[0036] Known pigtail catheters can be modified for use in conjunction with the present disclosure by attaching MR conditional markers at various locations such as the tip of the catheter and adjacent to the side ports or proximal to them. [0037] The markers, or “MR markers,” create negative contrast during interventional MRI on, for example, commercially available 0.55T or 1.5T scanners. Additionally, some or all of the side ports located proximally to the most proximal marker may be plugged.

[0038] The MRI-compatible guidewire may include an elongated body and may include a curved portion adjacent the distal end. MR conditional markers may be attached at various locations along the length of the guidewire to enable it to be visible during the MRI procedure.

[0039] Referring now to FIGS. 1 A and IB, the feasibility of using MR conditional markers 22 and 36 on the pigtail catheter 10 and the guidewire 26, respectively, is demonstrated by the use of these instruments for left heart catheterization on a 3D-printed heart phantom 38. In FIG. 1A, the MR markers 36 of the guidewire 26 are clearly visible in the aortic arch 40 of the heart phantom 38. FIG. IB, the MR markers 22 of the catheter 10 are shown inside the left ventricle (“LV”) cavity 42.

[0040] FIGS. 2A-C provide images of a pig study wherein the interventional cardiovascular MRI (iCMR) approach according to the present disclosure was used, including guiding the pigtail infusion catheter 10 into the LV. As shown in FIG. 2A, the guidewire 26 (markers 36 shown) was advanced through the femoral artery toward the aortic arch and into the LV by crossing the aortic valve. In FIG. 2B, the markers 20 of the pigtail catheter 10 are shown after the catheter 10 was advanced over the guidewire 26 through the ascending aorta into the LV chamber. FIG. 2C shows the pigtail catheter 10 fully placed inside the LV chamber and ready for intra-cardiac (“IC”) adenosine infusion (following removal of the guidewire 26) as is further described herein.

[0041] Referring now to FIG. 3, a process diagram is provided depicting the overall protocol 68 for the in-vivo practice of the teachings of the present disclosure. At step 70, localizer images are generated to identify the relative anatomical position of the cardiac areas of interest. As step 72, cine imaging is performed according to know techniques to obtain motion information over a selected time period. At step 74, Ferumoxytol is infused and, at step 76, the pigtail catheter 10 is placed in the LV under iCMR guidance. The process of placing the pigtail catheter 10 takes a first period of time 78, such as two minutes. At step 80, post-F erum oxy tol infusion rest T1 maps are acquired. Then, at step 82, dynamic beat-to- beat myocardial T1 maps are acquired every heartbeat. During step 82, as indicated by step 84, 5-fold diluted IC adenosine is infused over a selected time period such as 10-15 seconds. Following step 82, a waiting period of, for example, ten minutes is imposed as indicated by time period 86.

[0042] After the waiting period 86, which permits a return to baseline hemodynamics, IV adenosine is infused at step 88 with a high clinical dose (e.g., 210 mcg/kg/min) for an infusion period such as four minutes. At step 90, continuous dynamic myocardial T1 maps are acquired after a portion of the infusion period has lapsed, such as three minutes, corresponding to maximal hyperemia. During the steps 80 through 90, blood pressure is continuously recorded invasively from the femoral artery thereby covering a time period 92 that encompasses the IC adenosine infusion and the IV adenosine infusion.

[0043] Referring now to FIGS. 4A and 4B, representative results of rest and intracardiac adenosine stress T1 mapping are shown. FIG. 4A depicts myocardial T1 maps (1.8 x 1.8 mm² in-plane resolution) at rest and during hyperemia induced by IC adenosine infusion of step 84 (FIG. 3). The change (i.e., reduction) in myocardial T1 from rest to stress (i.e., from FIG. 4A to FIG. 4B) is referred to as “T1 reactivity” and as shown, the intramyocardial blood volume of two regions of interest from different coronary artery territories (i.e., region 94 and region 96) increases during IC adenosine infusion.

[0044] FIG. 5 depicts the actual dynamic myocardial T1 values for region 94 and region 96 before, during and after IC adenosine infusion. Data series 100 represents the T1 values for region 94 and data series 102 represents the T1 values for region 96. The shaded time period 104 between approximately 26 second and 51 seconds corresponds to the IC adenosine infusion step 84 depicted in FIG. 3. As shown, the T1 values for data series 100 and data series 102 decrease during time period 104 (i.e., during IC adenosine infusion) and then rapidly increase and substantially return to baseline values (i.e., pre-IC adenosine infusion values) of intramyocardial blood volume after the IC adenosine infusion has ended. [0045] Referring now to FIGS. 6A and 6B, bar plots are provided comparing the T1 reactivity (FIG. 6A) and the percentage of arterial pressure drop (FIG. 6B) for intracardiac (“IC”) infusion 106 vs. intravenous (“IV”) adenosine infusion 108. As shown in FIG. 6A, the myocardial T1 reactivity values for IC infusion 106 and IV infusion 108 of adenosine were similar. In this example, the T1 reactivities for IC adenosine infusion 106 were 5.6 +/- 0.8% and the T1 reactivities for IV adenosine infusion 108 were 5.9 +/- 0.4%, p = n.s. These similar reactivities were measured despite an approximately 20-fold lower amount of the stress drug (i.e., adenosine) infused and a 10-fold faster imaging procedure. The lower amount of infused adenosine and the more rapid imaging time provide reduced cost for the procedure of the present disclosure (e.g., at least in terms of drug cost and MRI scan time) and increased patient comfort and compliance, which may translate into improved diagnostic accuracy and procedure success rate.

[0046] In FIG. 6B, on the other hand, it is clearly shown that the IC adenosine infusion 106 had a markedly lower percent drop in mean arterial pressure (as measured invasively) compared to IV adenosine infusion 108. As lower pressure drop is associated with improved patent comfort during the procedure and a reduced number of failed “stress CMR” diagnostic procedures.

[0047] Any directional references used with respect to any of the figures, such as right or left, up or down, or top or bottom, are intended for convenience of description, and do not limit the present disclosure or any of its components to any particular positional or spatial orientation. Additionally, any reference to rotation in a clockwise direction or a counter-clockwise direction is simply illustrative. Any such rotation may be implemented in the reverse direction as that described herein.

[0048] Although the foregoing text sets forth a detailed description of embodiments of the disclosure, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent and equivalents. The detailed description is to be construed as exemplary only and does not describe every possible embodiment. Numerous alternative embodiments may be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims. [0049] The following additional considerations apply to the foregoing description. Throughout this specification, plural instances may implement components, operations, or structures described as a single instance. Although individual operations of one or more methods are illustrated and described as separate operations, one or more of the individual operations may be performed concurrently, and nothing requires that the operations be performed in the order illustrated. Structures and functionality presented as separate components in example configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements fall within the scope of the subject matter herein.

[0050] In various embodiments, a hardware module may be implemented mechanically or electronically. For example, a hardware module may comprise dedicated circuitry or logic that is permanently configured (e.g., as a special -purpose processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC)) to perform certain operations. A hardware module may also comprise programmable logic or circuitry (e.g., as encompassed within a general -purpose processor or other programmable processor) that is temporarily configured by software to perform certain operations. It will be appreciated that the decision to implement a hardware module mechanically, in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations.

[0051] Accordingly, the term “hardware module” should be understood to encompass a tangible entity, be that an entity that is physically constructed, permanently configured (e.g., hardwired), or temporarily configured (e.g., programmed) to operate in a certain manner or to perform certain operations described herein. Considering embodiments in which hardware modules are temporarily configured (e.g., programmed), each of the hardware modules need not be configured or instantiated at any one instance in time. For example, where the hardware modules comprise a general-purpose processor configured using software, the general-purpose processor may be configured as respective different hardware modules at different times. Software may accordingly configure a processor, for example, to constitute a particular hardware module at one instance of time and to constitute a different hardware module at a different instance of time.

[0052] Hardware modules may provide information to, and receive information from, other hardware modules. Accordingly, the described hardware modules may be regarded as being communicatively coupled. Where multiple of such hardware modules exist contemporaneously, communications may be achieved through signal transmission (e.g., over appropriate circuits and buses) that connect the hardware modules. In embodiments in which multiple hardware modules are configured or instantiated at various times, communications between such hardware modules may be achieved, for example, through the storage and retrieval of information in memory structures to which the multiple hardware modules have access. For example, one hardware module may perform an operation and store the output of that operation in a memory device to which it is communicatively coupled. A further hardware module may then, at a later time, access the memory device to retrieve and process the stored output. Hardware modules may also initiate communications with input or output devices, and may operate on a resource (e.g., a collection of information).

[0053] The various operations of example methods described herein may be performed, at least partially, by one or more processors that are temporarily configured (e.g., by software) or permanently configured to perform the relevant operations. In certain embodiments, the methods are performed by a controller that executes non-transitory computer-readable instructions stored on a memory device. Whether temporarily or permanently configured, such processors may constitute processor-implemented modules that operate to perform one or more operations or functions. The modules referred to herein may, in some example embodiments, comprise processor-implemented modules.

[0054] Similarly, the methods or routines described herein may be at least partially processor-implemented. For example, at least some of the operations of a method may be performed by one or more processors or processor-implemented hardware modules. The performance of certain of the operations may be distributed among the one or more processors, not only residing within a single machine, but deployed across a number of machines. In some example embodiments, the processor or processors may be located in a single location (e.g., within a home environment, an office environment or as a server farm), while in other embodiments the processors may be distributed across a number of locations. [0055] The performance of certain of the operations may be distributed among the one or more processors, not only residing within a single machine, but deployed across a number of machines. In some example embodiments, the one or more processors or processor-implemented modules may be located in a single device or geographic location (e.g., within a home environment, an office environment, or a server farm). In other example embodiments, the one or more processors or processor-implemented modules may be distributed across a number of devices or geographic locations.

[0056] Unless specifically stated otherwise, use herein of words such as “processing,” “computing,” “calculating,” “determining,” “presenting,” “displaying,” or the like may refer to actions or processes of a machine (e.g., a computer) that manipulates or transforms data represented as physical (e.g., electronic, magnetic, or optical) quantities within one or more memories (e.g., volatile memory, non-volatile memory, or a combination thereof), registers, or other machine components that receive, store, transmit, or display information.

[0057] As used herein any reference to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

[0058] Some embodiments may be described using the expression “coupled” and “connected” along with their derivatives. For example, some embodiments may be described using the term “coupled” to indicate that two or more elements are in direct physical or electrical contact. The term “coupled,” however, may also mean that two or more elements are not in direct contact with each other, but yet still co-operate or interact with each other. The embodiments are not limited in this context.

[0059] Additionally, some embodiments may be described using the expression “communicatively coupled," which may mean (a) integrated into a single housing, (b) coupled using wires, or (c) coupled wirelessly (i.e., passing data / commands back and forth wirelessly) in various embodiments.

[0060] As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0061] In addition, use of the “a” or “an” are employed to describe elements and components of the embodiments herein. This is done merely for convenience and to give a general sense of the description. This description, and the claims that follow, should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

[0062] The patent claims at the end of this patent application are not intended to be construed under 35 U.S.C. § 112(f) unless traditional means-plus-function language is expressly recited, such as “means for” or “step for” language being explicitly recited in the claim(s).

Claims

CLAIMS What is claimed is:

1. A method of performing rapid, minimally invasive MRI-based measurements of a biomarkers in an anatomy of a subject, comprising: intravenously infusing an intravascular MRI contrast agent into the subject; guiding a guidewire into a region of interest in the anatomy of the subject; inserting a catheter over the guidewire until the catheter reaches the region of interest; removing the guidewire; acquiring post-infusion baseline myocardial T1 maps of the region of interest; performing intracardiac infusion of a vasoactive agent into the region of interest using the catheter for a first time period; acquiring stress myocardial T1 maps of the region of interest during the intracardiac infusion of the vasoactive agent; and comparing the baseline myocardial T1 maps to the stress myocardial T1 maps to measure the biomarker.

2. The method of claim 1, wherein the intravascular MRI contrast agent is Ferumoxytol.

3. The method of claim 1, wherein the vasoactive agent is adenosine.

4. The method of claim 1, wherein each of the guidewire and the catheter comprise a MR marker configured to create negative contrast on an MRI scan.

5. The method of claim 4, wherein the MR markers are placed on a tip of the catheter and guidewire.

6. The method of claim 1, wherein the baseline myocardial T1 map is of the subject while at rest.

7. The method of claim 1, wherein the biomarker is ischemia.

8. The method of claim 1, wherein the area of interest is a left ventricle of a heart of the subject.

9. An MRI-guided diagnostic device configured to measure a biomarker in an anatomy of a patient, comprising: a guidewire configured to be inserted into an artery connected to a region of interest; and a catheter configured to advance along the guidewire into the region of interest; wherein the catheter is configured to intracardiaclly infuse a vasoactive agent into the region of interest.

10. The MRI-guided diagnostic device of claim 9, wherein the catheter is a pigtail catheter.

11. The MRI-guided diagnostic device of claim 9, wherein the region of interest is the left ventricle of a heart.

12. The MRI-guided diagnostic device of claim 9, wherein at least one of the guidewire and the catheter further comprise an MR marker configured to create negative contrast on an MRI scan.

13. The MRI-guided diagnostic device of claim 12, wherein the MR markers are placed on a tip of the catheter and guidewire.

14. The MRI-guided diagnostic device of claim 9, wherein the vasoactive agent is adenosine.