Cardiac MRI Imaging: What can the Power of the Magnet do for Our Patients

Transcription

1 Cardiac MRI Imaging: What can the Power of the Magnet do for Our Patients Jennifer Dickerson MD FACC Medical Director Ross Echocardiography Lab Assistant Director Cardiac MRI/CT Quality Assurance

2 What do we do as clinicians? Listen Examine Review existing data IDENTIFY INFORMATION NEEDS Establish diagnosis, prognosis Deliver optimal prevention, treatment Develop new therapies based on better understanding of disease mechanisms

3 Atherosclerosis Heart failure Valvular disease Arrhythmias Congenital heart disease Prevention Acute Therapies Post-Event Stabilize noncritical plaque Treat asymptomatic LV dysfunction Retard lesion progression, define aortopathy Reduce triggers of Atrial Fib. Treat asymptomatic RV dysfunction Revascularization ICDs in high-risk post-mi patients Volume management Valve replacement Ablation Percutaneous shunt closure What is the underlying substrate for arrhythmia? Who is high-risk? Will LV function improve? Bi-V pacing, transplantation How severe is the regurgitation? Precision in diagnosis precedes rational therapy. C. F. Wooley, MD SBE prophylaxis Pacemakers Anticoagulation

4 Ways to Image the Heart Electrical Waves (Electrocardiogram) Sound Wavesultrasound (Echocardiogram) Nuclear Energy (SPECT, MUGA, CT and PET) Spinning Hydrogen Photons in a Magnetic Field (MRI) 4

5 Power of Cardiac Imaging Cardiac Structure Cardiac Function Ejection Fraction Stress Testing Viability Vascular Imaging Congenital imaging Tissue Characterization 5

6 What do magnets have to do with my heart? Our bodies are made of >60% hydrogen; >90% water (H 2 O) Hydrogen atoms are like little magnets, pointed in random directions In a magnetic environment, they line up with the magnetic field By changing the magnetic field with radio waves, we get information about the hydrogen in molecules anywhere in the body Hydrogen atom (little magnet) MRI Scanner (big magnet)

7 + + Protons (H 1 ) in water Static/Gradient Magnetic Field Radiofrequency (RF) Pulse Reception of RF Signal + Image Reconstruction = Courtesy Dr. Alex Auseon

8 Cardiovascular MR: How We Do It Before the procedure: patient history Before the procedure: screening Contraindications to MR: ferromagnetic foreign body, pacers/icds, retro-orbital metal (MRISafety.com) Severe renal insufficiency if MRI contrast (gadolinium used) These are OK: sternal wires, prosthetic heart valves, stents, orthopedic hardware

9 Caveats of Cardiovascular MR Discomfort due to noise, laying flat, claustrophobia. Larger bore scanner available. MRI compatible ventilators, pumps.

10 Use of MRI IV contrast (gadolinium) for scar imaging: A Tail of Two Phases injection Normal Myocardium Delayed Enhancement Infarcted Myocardium Ischemic Myocardium < 1 min > 5 min First-Pass time

11 CMR for Ventricular Function

12 55 y/o M with CHF

13 DME: LAD-territory infarct scar

14 LV EF 26% Fixed abnormalities with stress Extensive, transmural scar (30% of myocardium)

15 Scar and Post-MI Risk How much of my heart has been damaged? Transmural extent of infarct Ventricular arrhythmias Adverse remodeling Heart Failure

16 Post-MI Remodeling acute MI (hrs) infarct expansion (hrs to days) global remodeling (days to months)

17 Infiltrative Cardiomyopathies Cardiac Biopsy samples only part of the heart. MRI samples the entire myocardium Sarcoidosis Amyloidosis Hemochromatosis Chagas disease Glycogen Storage diseases (Gaucher s disease, Anderson-Fabry disease, etc.)

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19 36 y/o African-American male with palpitations, near-syncope PMH: sarcoidosis PE, echocardiogram unremarkable CMR to assess for myocardial sarcoid

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21 42 y/o male with atrial fibrillation refractory to drug therapy FH: no known cardiovascular disease PE: unremarkable Echocardiogram: low-normal EF CMR exam to delineate pulmonary veins preablation

22 Dx: arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) Change in management: -RFA plus ICD placement -Screening of family members

23 Myocarditis Infection in the heart muscle Autopsy prevalence of % of Sudden Cardiac Death in young adults While heart biopsy typically involves 4-6 samples, postmortem study suggests >17 samples needed to make diagnosis >80% of the time 1 1-Hauck AJ et al. Mayo Clin Proc 1989.

24 Myocarditis CMR Cine Images Markedly abnormal DME-CMR Small focus of mononuclear cells Dickerson _ ACC 08

25 Hypertrophic Cardiomyopathy Variety of genotypes and phenotypes >200 mutations in 10 different sarcomeric genes Asymptomatic, mildly symptomatic, arrhythmias, heart failure, SCD Substrate for arrhythmia may be myocyte disarray and scar

26 39 y/o anxious male with palpitations FH: HTN, MVP PE: systolic murmur that increased with standing Echo: asymmetric septal hypertrophy, no LVOT gradient Medical management--persistent PVCs CMR to define arrhythmia substrate

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28 Family 1: late onset slow progression No pt with SCD Family 2: early onset rapid phenotype development Proband had SCD at age 18

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30 Predicting Resynchronization Therapy Response 40 ICMP patients referred for CRT EF 35%, LBBB, QRS >120ms Baseline CMR: scar location, transmurality Baseline, post-implant TDI Y/N dyssynchrony: septal-to-lateral wall delay 65ms Baseline, 6-month clinical assessment incl. NYHA class, 6-minute walk, QOL score Bleeker GB et al. Circ 2006; 113:

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32 Navigator Localization

33 33 Bicuspid Aortic Valves

34 PDA PDA 26 year-old with chest pain Machinery-type continuous murmur on exam

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36 Recoarctation

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38 4.6cm 1.9cm 4.1cm

39 Cardiac Tumors Clinical Questions Impact on cardiac function Feb 2006 (LVEF 40%) Oct 2006 (LVEF 15%)

40 DDx: malignant vascular tumor with pericardial involvement Tissue diagnosis: Angiosarcoma

41 Multilevel Peripheral Artery Disease

42 Occluded Aorta

43 Left Common iliac stenosis

44 OSU CMR/CT Team Subha Raman MD Jennifer Dickerson MD Alex Auseon MD Sharon Roble MD Karolina Zareba MD Anne Garcia, RT Non-invasive Nursing Lon Simonetti, PhD Beth McCarthy, RT Debbie Scandling