The purpose of this page is to familiarize you with the planes, sequences, and protocols used in cardiac MR.  Sequence descriptions are kept to a minimum here and are discussed in one of the recommended readings.   This page focuses instead on obtaining the proper imaging planes for performing a cardiac MR exam. Once you know how to get the planes you can put them together to form actual cardiac MRI protocols.  To scroll though multi plane stacks (images with borders), click on the image and use the "<" and ">" keys.

 

CMR Sequences

 

 

 

CMR Planes

 

 

Basic CMR Protocols

 

 

 

Dark Blood

 

Dark blood images null the signal from blood using the double inversion recovery (DIR) technique, which is not discussed further here.  DIR sequences can be fast spin echo, in which case each image is acquired in a separate breath hold, or single shot, in which case multiple images are acquired in one breath hold.  DIR images are always gated to the EKG so that cardiac motion is removed from the images.  These sequences are used to determine anatomy.

 

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Bright Blood

 

Bright blood technique is either a balanced steady state (TRUE FISP or FIESTA) or a more conventional gradient echo (GRE) sequence.  TRUE FISP is faster and has better signal to noise and contrast to noise ratios, but is more susceptible to metal artifact and magnetic field inhomogenieties.  This is the sequence we use most often to watch the heart beat.  GRE is more sensitive for detecting turbulent jets but has lower contrast and the images take longer to acquire.  You might use GRE if you are looking to see the subtle jet of an ASD or VSD.  Both techniques are gated to the EKG to produce movies of the beating heart.  Generally, 1 slice is obtained per breath hold.  These images are used to assess cardiac function by watching the heart beat.

 

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Triple Inversion Recovery

 

Fast spin echo sequence is a double inversion recovery STIR  Edema and fluid are bright.  This is used to look for myocardial edema from myocarditis or active inflammatory disease.  The images are gated to the EKG.  Generally, one image is obtained per breath hold.  Since this is a STIR the sequence is run pre-contrast.

 

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Delayed Myocaridal Enhancement (MDE)

 

Post contrast sequence used to evaluate for myocardial scar.  Normal myocardium enhances and then washes out.  Myocardial scar enhances late.  An inversion recovery pulse is used to null the signal from normal myocardium and make the scar more conspicuous.  The optimal inversion time (TI) is different for each patient and is determined by you and manually entered into the sequence to optimize results.  MDE images are obtained 10-15 minutes after contrast injection to give the scar time to enhance.

 

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Phase Contrast

 

This is a gradient echo sequence used to measure blood velocity.  By integrating pixel velocities across a vessel volume flows can be calculated.  Velocity measurements are used to estimate pressure gradients.  Volume flows are used to calculate stroke volumes, estimate shunt fractions (by comparing pulmonary versus systemic flow), and for assessing the severity of valvular insufficiency (by measuring regurgitant fractions).  You must estimate the maximum velocity of the blood in the vessel you are imaging prior to running the sequence.

 

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Axial Scouts:

 

 

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Vertical Long Axis (VLA)

 

 

    

 

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Fake Short Axis

 

 

   

 

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True 4 Chamber (4CH)

 

 

 

   

 

 

LA = Left Atrium, LV = Left Vetricle, RA = Right Atrium, RV = Right Ventricle, A = Aorta

 

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Short Axis Stack (SAS)

 

 

  

 

 

 

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Short Axis for T2 FS, T2 Mapping, T1 Mapping, Perfusion

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Left Ventricular Outflow Tract

 

 

 

LV = Left Ventricle,  LA = Left Atrium, RV = Right Ventricle

 

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Right Ventricular Outflow Tract

 

 

  

 

RV = Right Ventricle, RVOT = Right Ventricular Outflow Tract, PA = Pulmonary Artery, LA = Left Atrium, A = Aorta

 

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Pulmonary Artery

 

 

 

  

 

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Phase Contrast Aorta

 

 

  

 

RPA = Right pulmonary artery

 

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Phase Contrast PA

 

 

  

  

 

PA = Pulmonary Artery (in cross section), a = aorta

 

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Aortic Valve

 

 

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TI scout

 

 

 

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MDE images

 

 

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Delayed Enhancement Study:

 

The purpose of this protocol is to evaluate the myocardium for scar which can be secondary to prior infarct, infiltrative disease, myocarditis, or cardiomyopathy.

 

 

 

 

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Congenital Heart Disease Study:   repaired CHD, question shunt

 

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Breath hold or free breathing?

 

End expiration breath hold is the most reproducible technique.  This is important because you will be making volume measurements off of the images. However, this is the most difficult for the patinet.  I find I get the best results with multiple short end expiratory breath holds.  I try to keep the breath hold time to less than 8 seconds.

 

Tips

 

Use oxygen

Revert to end inspiration if necessary

Have free breathing sequences available to use as a last resort.  Free breathing sequences will have decreased resolution and use multiple aveages.