Cardiac MR -Complimentary -Competitor -Conqueror ?

Dr Girish Dwivedi MRCP (UK), PhD (UK), FASE

Staff Cardiologist, Assistant Professor in Medicine

University of Ottawa Heart Institute

University of Ottawa, Canada

Today’s talk

Physics

Indications and Examples

Safety

Questions

Nishimura DG. Principles of MRI. & Lawson Imaging 3-T facility, Siemens Verio

Body lies on table encompassed by coils for

static field (Bo), gradient fields (Gz and Gx

shown), and radiofrequency field (RF or B1).

Physics

Which is likely to result in most harm or damage?

A. Putting a patient with mechanical valves and sternal wires in MRI.

B. Putting a patient with reveal device, stents or ASD occluder in MRI.

C. Putting a patient with Pacemaker in MRI.

D. Putting a patient with intracranial clip in MRI.

E. Returning home late after finishing consults and forgetting your sigmificant others birthday.

MRI: Mapping abundance & behavior of hydrogen nuclei in tissues.

Tissues are largely water and fat

many hydrogen atoms (humans are ~ 63% hydrogen!)

Hydrogen nucleus comprised of a single proton

Each proton can be viewed as a small magnetic field

Bare H proton has a nuclear spin, and total angular momentum

Physics

My old boss

Difference between Iron and Steel

Ferromagnetic

Paramagnetic

Diamagnetic

Processing

How does it work?

T1 weighted Spin echo Gradient echo

So where is it useful, really?

Left ventricular function

Ischaemic Heart disease – One stop

Cardiomyopathy – Dare you do it without CMR?

“Fascinomas”

Congenital heart disease

And just about every other cardiac and great vessel disease………….

So why bother?

No dependence on acoustic windows – can “always” get good quality images

Can do things echo can’t – New perspectives on common diseases

Can pick any plane

Accurate

Reproducible

No radiation

Image quality

It’s not all good news

Expensive

Fixed

Not real time

Cardiac/respiratory artefacts

Resolution

Portability

1. CMR LV function

Base

Apex

LV-RV stroke volumes in normal hearts

Longmore Lancet 1985; 1360-2

Pennel, AHJ, 2002

Echo 230

CMR 28

Reduce number of subjects in trials

2. Ischaemic heart disease

IHD

Bulk of our work

Myocardial Ischaemia

Stress wall motion

Stress perfusion

Myocardial viability

Complications of IHD

Coronary angiography

Hibernating myocardium

Hibernating myocardium

Hypokinetic myocardium which has the potential to improve in function

Cellular integrity

Late enhancement Gd

TTC MRI

R Judd, Northwestern University, Chicago

Validation of Gadolinium Hyper enhancement in CMR

This is something unique:

Imaging “dead” heart muscle as well as live heart muscle

Transmural Extent of Scar and Functional Recovery

Kim R, ACC Sessions 2000

Gadolinium

Cine Late Gad

Case example

83 years old

Little comorbidity

Severely limited by SOB

Severe 3 vessel disease

Severely impaired LV function.

CMR- Pre CABG

CMR- Post CABG

Myocardial Perfusion

Stress

Rest

Coronary artery imaging

Radiation

Ca scoring X Ray angio CT angio

Cardiac MR Echo Exercise testing

Anomalous RCA with Inter-arterial Course

LAD

LCX

R

L NC

Pulmonary trunk

RCA

Can it be done?

Li D. Radiology 1996; 201: 857-63.

3 Tesla coronary MR

But

Not robust

Not reproducible

Resolution

Technical issues

Time

Is it what we need?

3. Cardiomyopathy

HCM

Apical HCM

Case example

Right ventricular cardiomyopathy

ARVC

Iron cardiomyopathy

Before

And after

Congenital heart disease

Quadricuspid Aortic Valve

Complex ACHD

Next Images

It’s an attempt to image the first test baby by echo and shows a normal heart

No, they represent Zebra fish embryo heart.

Actually, a resident (this time medicine) is trying image an abnormal heart.

None or all the above

Echo: Unclear Apical views

Congenital Heart Disease (real case)

Abdominal and atrial situs solitus, AV/VA concordance.

Malposition of the great arteries

Tricuspid atresia

Dextrocardia

Juxtaposed right atrial appendages

Acquired pulmonary atresia

Aged 6 weeks right classical Blalock-Taussig shunt

Aged 4 years left classical Blalock-Taussig shunt

Aged 7 years modified Fontan operation (SVC to right pulmonary artery,

right atrial appendage to left pulmonary artery)

Fontan operation

Done in single ventricle circulation

Congenital cardiac malformation in which one ventricle is dormant or biventricular repair is not possible

3D non-contrast enhanced MRI

Mechanical valves, annuloplasty rings-OK ASD device, PFO, Duct closure etc-OK Stents: OK Pacemaker, ICD-XX Sternal wires, epicardial wires-OK Catheters if poly urethane or PVC OK LVAD and IABP-XXXX www.mrisafety.com. www.radiology.upmc.edu/MRsafety. www.IMSER.org

Guidelines for 1.5 T scanner

Safety

Gold standard

1. Ventricular volumes

2. Ventricular function

3. Complex congenital heart disease

4. Imaging of other structural abnormalities

5. Myocardial viability

6. (aortic disease)

On it’s way

Myocardial perfusion imaging

Coronary artery imaging?

Quantification of

Myocardial function

Scar

Perfusion

The Future

Single examination for CAD

MR spectroscopy

Real time imaging

Thank you