This document discusses cardiac MRI (CMRI) and its clinical applications. CMRI provides anatomical and functional information to assess heart abnormalities through various sequences like ECG-gated bright and dark blood sequences. It is useful for evaluating congenital heart diseases, valvular heart diseases, ventricular function, coronary arteries, myocardial perfusion and viability, cardiac masses, and pericardial diseases. CMRI is more accurate than echocardiography for measuring ejection fraction, volumes, and assessing ventricular function and viability. It is useful for differentiating conditions like arrhythmogenic right ventricular dysplasia, restrictive vs constrictive cardiomyopathy, and determining feasibility of revascularization procedures.

1. Cardiac MRI
Rahman Ud Din
Lecturer Medical Imaging
NWIHS

2. Introduction
• CMRI
• Information to assess the abnormality of heart
• Anatomical and functional information
• Acquired or congenital heart diseases
• Modality of choice
▫ ARVD,
▫ Differentiation from constrictive pericarditis from
restrictive pericarditis, aortic dissection
▫ Precise quantification of ventricular dimensions
▫ Myocardial viability and perfusion
ARVD

3. ECG Gating
• ECG/EKG gating essential for motion-free image
of heart
• Images are acquired in a particular phase of
cardiac cycle in every cardiac cycle
• To avoid image blur and motion artifacts
• The image is decided by ECG gating
• Usually R-wave is used to trigger the acquisition
• Such data acquired in the diastolic phase
• Peripheral pulse also used for gating
• But less effective than ECG gating

4. Imaging Sequences
• Pulse sequences used
▫ Dark-blood sequences
▫ Bright-blood sequences
• Dark-blood tech
• Spin-echo seq; that show the flowing blood as flow
void
• Seqs; include breath-hold turbo or FSE (TSE,
FSE)
• Single shot FSE
• Double inversion recovery FSE (Double-IR-FSE)

5. Bright blood technique
• GRE seq: based shows blood bright
• Seqs; include spoiled GRE
▫ (turboFLASH/SPGR/T1-FSE)
▫ Balanced SSFP (TrueFISP/FIESTA/balanced TFE)
• Balanced TFE is mainstay seq; in CMRI
• Motion loop is obtained rapid cine imaging (RCI)
• Used RCI used ventricular function
• To calculate EF, SV as well as valvular & RWM
• Phase contrast useful in velocity & flow direction
• Initial CMRI starts from black blood than bright
blood techniques used to assess functions

6. Imaging planes
• Orthogonal planes (axial, sagittal and coronal)
• Used for chest imaging and not suitable in CMRI
• Because cardiac axes are not parallel to body axes
• Three axes images are taken and used as localiser

7. 1. Vertical long-axis
plan (two chamber
view)
• Axial image
• Large oblique
diameter image of LV
• Chambers; LA and
LV

8. 2. Horizontal long-axis (Four
Chamber view)
• Planned on two chamber
view
• By a drawing line passing
through LA, MV & LV
• All four chambers, MV and
TV assessed
• Cine GRE images obtained
on this plane to assess
function of MV, TV, AV and
LV, RV wall motion

9. 3. Short-axis plane
• Multiple cross sections are
obtained perpendicular to
LV long axis as seen on a
two-chamber view
• Sections are taken from the
base to the apex of the
heart
• Cine GRE images allow
visualization and
quantification of systolic
myocardial wall thickening
• Images in this plane are
used for calculating
ventricle volume, mass and
EF by postprocessing

11. 4. Five-Chamber view
• View obtained parallel
to the line passing
through the LV apex
and aortic outflow tract
on coronal images
• Apart from all four
chambers, this view
also shows aortic root
• This describe MV and
AV

12. 5. RVOT
• Plane passing through the RV outflow tract

13. Clinical Applications of CMRI
1. Congenital Heart Disease (CHD)
• Complex information about heart anatomy
• When echocardiography fail
• ASD, VSD detected with high sensitivity &
specificity
• Calculate shunt size
• Conditions like
▫ TGA (transposition of Greater Arteries)
▫ Truncus arteriosus
▫ Many anomalies
CMRI in children are having limitation

14. ASD
Truncus
arteriosus

15. 2. Valvular Heart Disease (VHD)
• Arrhythmogenic right ventricular dysphagia
• Enlargement and dilatation of RV
• Thinning of wall, area of dyskinesia, focal
bulging of free wall in systole
• Decreased EF and impair ventricular filling
during diastole
• HCM (Hypertrophied)
▫ Echo detect but RV involvement is checked CMRI
• RCM (Restrictive) vs Constrictive
▫ Constrictive calcified pericardium, WT + 4mm
• Hemochromatosis
▫ Myocardial iron deposition i.e. Thalasemia
▫ Quantified by T2*-w seq;

16. 4. Ventricular Function
• CMRI more accurate than Echo
• It measure EF, EDV & ESV (end systolic vol)
• Done on short axis image using software
• Balanced SSFP, good contrast b/w blood pool
and myocardium

17. 5. Coronary artery assessment
• Not good enough for visualisation of coronary
arteries and its branches
• Presently it is used for such purpose, to find
anomalies, aneurysms and bypass grafting
patency
• GRE seq; balanced SSFP C+ or C-

18. 6. Myocardial perfusion and viability
• IV Gd
• T1-weighted GRE seq; turboFLASH
• Low signal areas of underperfusion on these images
correspond with regions of ischemia or infarct
• Myocardial viability
▫ Viability seq; run after 10-15 minutes after Gd contrast
▫ T1-w GRE or inversion recovery balanced SSFP seq
▫ IR pulse used to suppress myocardium to get LV info
▫ Proper TI is important
▫ Infracted area on viability imaging shows enhancement
▫ This imaging is ‘Bright is dead’
▫ Answer feasibility revascularisation procedure like
angioplasty and bypass or not
▫ CMRI viability is superior compared to the PET

19. 7. Cardiac and Pericardial masses
• CMRI accurate method for cardiac and
pericardial masses evaluation
• Thrombus the most common filling defect in
cardiac chamber
• Gd enhancement differentiate b/w mass or
thrombus
• Most cardiac neoplasm are metastatic
• Primary neoplasm are rare and 80% benign

20. 8. Pericardial disease
• Visualised with spin echo or GRE images
• Normal pericardium seen on SE images
• As a line of low signal intensity located b/w high
signals of pericardial and epicardial fat
• Normal thickness 1-2 mm; more than 4 mm is
considered thickening