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Cardiovascular MRI 2016 Current Practices, Future Direction

Elden R. Rand, MD, MS, FACC, FACP, FASNC, FASE, FSCCT Cardiologist-Invasive, Noninvasive, Advanced Imaging

North Central Heart Institute

Disclosures Dr. Rand has no relevant financial or nonfinancial relationships to disclose. This presentation will involve discussion of investigational or unlabeled use of commercial products, devices, or pharmaceuticals that has not been approved for such purpose by the FDA. (gadolinium, ferumoxytol)

Outline I. History of MRI and cardiac MRI II. MRI Physics III. MRI “Contrast” – Gadolinium and ferumoxytol IV. Benefits/Limitations of MRI V. Uses of Cardiovascular MRI VI. History of CM MRI in our Region VII. Examples VIII. Future of Cardiovascular MRI

History Jean Baptiste Joseph Fourier (1768-1830) – Mathematical transformation method Nikola Tesla (1856-1943) – rotating magnetic field, AC machinery, Tesla coil Sir Joseph Larmor (1857-1942) – Larmor equation- frequency/magnetic field 1946 – Felix Bloch (Stanford) and Edwin Purcell (Harvard) -- independently reported phenomenon- Nuclear Magnetic Resonance -- Nobel prize in physics to both – 1952 1966 – Richard Ernst -- Apply Fourier transformation to NMR spectroscopy -- Improved the sensitivity of generating NMR signal --Provided platform for development, speed, performance -- Nobel Prize 1991 1970’s – Paul Lauterbur and Peter Mansfield --Added magnetic field gradient to spectrometer --Proved a means to vary resonance from point to point --Provided a means to generate an image --Nobel Prize 2003 d

Pohost, GM. The History of Cardiovascular Magnetic Resonance, JACC: Cardiovascular Imaging; 2008;Vol 1 No 5. Geva, T. Magnetic Resonance Imaging: Historical Perspective. SCMR; 2006;8, 573-580).

History

1980’s – Advancement and development of NMR at various sites – Harvard, England 1980– earliest seeds of cardiac MRI at Massachusetts General Hospital 1981 -- use of NMR in imaging cerebral infarction (animal models) 1984 – “NMR. Potential applications in clinical cardiology” (Pohost, et al, JAMA). 1984 – T1/T2 relaxation times differ in infarcted and normal myocardium after gad. 1986 – Official nomenclature change from NMR to MRI Supposed concern for patients getting a “nuclear process” during imaging 1993 – first report of using gadolinium for delayed enhancement of MI. 1999 – Contrast enhancement in acute MI, reversible ischemic injury, chronic MI - dogs 2000– Delayed imaging identifies reversible myocardial dysfunction -50 patients imaged before/after PCI or CABG

Westbey, et al. Radiology. 1984;Ict;153(1):165-9. Pohost, GM. JACC: Cardiovascular Imaging; 2008;Vol 1 No 5. Fieno, Kim, Chen, et al. JACC 2000;36:1985-1991. Kim, Wu, Rafael, Chen, et al NEJM 2000;343;1445-1493.

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MRI Physics Basis of MRI: 96% of human body is Oxygen, Hydrogen, Carbon, Nitrogen Hydrogen is 9.5%. In ionic state, hydrogen is a proton (H+) Protons 1. Positively charged 2. Possess quantum property of spin (“Wobble”)

MRI Physics Overall concepts:

• Place the patient in a strong stationary magnet – aligns the spins • Use radiofrequency (RF) coil to apply energy to the hydrogen nuclei • Spin is altered depending on several factors. • RF signal is turned off. • As spins return to base state, they release their energy • Energy is measured by a receiver coil and converted to electric signal.

MRI Physics Equipment needed: Very strong magnet with precise/homogeneous magnetic field Strong/precise field generation to generate gradients – localize signals. Precise coils to send and receive signals Fast computer processing (Fourier analysis)

MRI Physics “The Magnet” 1.5 Tesla typical magnet strength. 1 Tesla = 10,000 Gauss Earth Magnetic Field = 0.5 gauss 1.5 Tesla magnet is ~30,000 times Earth’s Magnetic Field Superconductor basis using liquid helium (4K = -269oC = -454.2oF) And…

THE MAGNET IS ALWAYS ON !!!

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Do Not Enter an MRI Area with Unauthorized equipment

MRI Contrast Contrast agents used during MRI when needed Gadolinium Ferumoxytol

Gadolinium Gadolinium

• A paramagnetic metal ion • Moves differently in a magnetic field • Is chelated to a large organic molecule to stabilize and reduce toxicity • Renally cleared • Also commonly used for MRA

Not FDA approved. No other agents are either.

• May increase risk of developing Nephrogenic Systemic Fibrosis in patients with severe renal insufficiency (GFR<30).

• Gadolinium contrast Shortens T1 relaxation- increasing T1 signal Gd washes out of scar or fibrotic tissue more slowly than normal myocardium. This is the Basis of Delayed Enhancement Imaging “Bright Is Dead”

Ferumoxytol Ferumoxytol FDA approved iron replacement in patients with renal insufficiency Superparamagnetic iron compound. Becoming more popular for use in MRA in patients with renal insuff. Not used for Delayed Enhancement Imaging Not FDA approved for MRA Anaphylaxis risk/monitoring

The ferumoxytol in renal insufficiency study (FiRST) Sreekanth Vemulapalli1*, Lucien Abboud4, Cassidy Duran2, Igor Klem1, Han W Kim1, Anna Lisa Crowley1, Miguel A Quinones2, Faisal Nabi2, John P Middleton3, William A Zoghbi2, Raymond J Kim1 and Dipan J Shah2 Journal of Cardiovascular Magnetic Resonance 2013, 15(Suppl 1):P228 doi:10.1186/1532-429X-15-S1-P228

Benefits / Limitations of MRI Benefits: No ionizing radiation No iodinated IV contrast Excellent resolution of tissue differences Gold standard for many cardiology conditions For certain conditions, MRI is a “one-stop-shop” – single study provides info rather than multiple modalities. Limitations Requires MRI scanner with coils and proper software Requires trained technicians/physician imager for optimal results Certain patient implants/devices cannot be put in MRI scanner Increased time for imaging (as compared to CCTA or Echo)

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Some Uses of CV MRI/MRA Heart Morphology and Function Cardiomyopathy evaluation Hypertrophic cardiomyopathy Sarcoidosis/Amyloidosis/Iron overload/ARVC Tumors Thrombus Pericardial diseases Unclear EF/wall motion by other modalities Congenital Heart Disease Scar/Fibrosis analysis - Evaluate Viable myocardial tissue – who to revascularize MRA Aorta evaluation- following aneurysm, post-repair monitoring Carotids Peripheral Arterial Disease Pulmonary Vein mapping prior to Atrial Fibrillation Ablation Coronary angiography- anomalous coronary artery origin MRI Stress testing – adenosine or dobutamine Structure, Function, Ischemia, myocardial scar

The History of CMR Locally

<2016 - Patients who could benefit from CV MRI were sent to Omaha, Minneapolis, or Rochester for their studies. No program in our region at any site in Sioux Falls region.

2011-2014: Initial concepts at NCH for a cardiovascular MRI program.

Dr Rand - prior CMR training and experience.

2014-Collaboration with Avera McKennan to develop and implement a CMR program using the new MRI magnet at Avera McKennan.

9/2014- 5/2015 Formal CV MRI fellowship training at Duke University.

12/2015: Pilot: GE imaging specialist on site. Several patients with known conditions scanned.

1/2016: First formal Cardiovascular CMR program in region launched.

To date, remains the only Cardiovascular CMR program in region.

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Timeline Timeline

Due to need to coordinate with other inpatient/outpatient studies, CMR program started with 2 scanning days per month, and we have increased scheduled days on a quarterly basis as per demand, with add-on studies (e.g. inpatients or more urgent requirements) as needed.

As of this month, 66 studies have been done.

Reasons for CMR Ordering 2016

CM Eval

48%

Viability

21%

Arrhythmia 21%

Mass/Thrombus 4%

Aorta/Vasc 3%

Pectus/Chest 2%

Valvular 1%

Some of these are from our program, others are excellent demonstrations of rarer findings from

Duke.

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CMR Examples BICUSPID AORTIC VALVE

CMR Examples

MECHANICAL VALVE

CMR Examples

Hypertrophic Cardiomyopathy

CMR Examples

Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

CMR Examples Left Atrial Myxoma

CMR Examples Metastatic Melanoma (with coronary sinus infiltration)

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CMR Examples

ENDOMETRIAL CANCER (note pericardial involvement)

CMR Examples Left Anterior Descending Artery Ischemia

SHORT AXIS REST PERFUSION STRESS PERFUSION

DELAYED ENHANCEMENT (None; no scar)

Present and Future Local Advancement: Plan to start CMR stress testing in spring/summer Increase CMR for valve disease/shunt analysis In the CV MRI world: Faster acquisition – less time in magnet Increased magnetic gradient technology – improved imaging Further refinement of 3 Tesla MRI systems - excellent images, but higher field strength poses unique challenges. Increase in stress MRI testing Further delineation of gadolinium based contrast and NSF Alternative MRI contrast agents T1 mapping, T2 mapping

Source: http://4dlab.northwestern.edu/wp-content/uploads/sites/7/2014/08/tpm-images.jpg

4D Flow Data Analysis Visualization of blood flow, peak velocity, regurgitation, net flow, advanced flow parameters.

Aortic Coarctation Source: http://4dlab.northwestern.edu/2-advanced-4d-flow-data-analysis/

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Summary CV MRI - No ionizing radiation - No iodinated contrast exposure - Gold standard for many cardiac conditions - Safety issues for certain implants/devices - The magnet is always on.

Thank you