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
Physics Body lies on table encompassed by coils for static field (B o ), gradient fields (G z and G x shown), and radiofrequency field (RF or B 1 ). Nishimura DG. Principles of MRI. & Lawson Imaging 3-T facility, Siemens Verio
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.
Physics 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
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
Apex Base
LV-RV stroke volumes in normal hearts Longmore Lancet 1985; 1360-2
Reduce number of subjects in trials Echo 230 CMR 28 Pennel, AHJ, 2002
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
Rest Stress
Coronary artery imaging
Radiation Ca scoring X Ray angio CT angio Cardiac MR Echo Exercise testing
Anomalous RCA with Inter-arterial Course RCA Pulmonary trunk LCX NC R L LAD
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
Safety 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
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