Cardiovascular Magnetic Resonance

Cardiovascular Magnetic Resonance

Cardiovascular Magnetic Resonance (CMR), sometimes know as cardiac MRI is a medical imaging technology for the non-invasive assessment of the function and structure of the cardiovascular system. It is derived from and based on the same basic principles as Magnetic Resonance Imaging MRI but with optimisation for use in the cardiovascular system. These optimisations are principally in the use of ECG gating and rapid imaging techniques or sequences. By combining a variety of such techniques into protocols, key functional and morphological features of the cardiovascular system can be assessed.

An example of CMR movies in different orientations of a cardiac tumor - in this case, an
atrial myxoma. The full case can be seen [ here]

History of CMR and Nomenclature

The phenomenon of nuclear magnetic resonance (NMR) was first described in molecular beams (1938) and bulk matter (1946), work later acknowledged by the award of a joint Nobel prize in 1952. Further investigation laid out the principles of relaxation times leading to nuclear spectroscopy. In 1973, the first simple NMR image was published and the first medical imaging in 1977, entering the clinical arena in the early 1980s. In 1984, NMR medical imaging was renamed MRI. Initial attempts to image the heart were confounded by respiratory and cardiac motion, solved by using cardiac ECG gating, faster scan techniques and breath hold imaging. Increasingly sophisticated techniques were developed including cine imaging and techniques to characterise heart muscle as normal or abnormal (fat infiltration, oedematous, iron loaded, acutely infarcted or fibrosed).As MRI became more complex and application to cardiovascular imaging became more sophisticated, the Society for Cardiovascular Magnetic Resonance, [] SCMR was set up (1996) with an academic journal, (JCMR) in 1999, which is going open source in 2008. In a move analogous to the development of ‘echocardiography’ from cardiac ultrasound, the term ‘Cardiovascular Magnetic Resonance’ (CMR) was proposed and has gained acceptance as the name for the field.

Physics of CMR

CMR uses the same basic principles as other MRI techniques with the addition of ECG gating. Most CMR uses only 1H nuclei MR, which are abundant in human tissue. By using magnetic fields and radiofrequency (RF) pulses, the patients own 1H nuclei absorb and then emit energy, which can be measured and translated into images, without using ionising radiation. For further information, see MRI, earlier versions of this document, or the following outside links:


[ Hull physics lecture series]

[ the basics of MRI]

[ MRI tutor]

The different techniques in CMR

CMR uses several different techniques within a single scan. The combination of these results in a comprehensive assessment of the heart and cardiovascular system. Examples are below:

Visualising heart muscle scar or fat without using a contrast agent

Typically a sequence called spin-echo is used. This causes the blood to appear black. These are high resolution still image which in certain circumstances identify abnormal myocardium through differences in intrinsic contrast.

A short axis view of the heart showing a movie (cine)next to a spin-echo sequence. In this case, the scan demonstrates features of ARVC with fatty infiltration of the left and right ventricles. The full case can be seen [ here]

Heart function using cine imaging

Images of the heart may be acquired in real-time with CMR, but the image quality is limited. Instead most sequences use ECG gating to acquire images at each stage of the cardiac cycle over several heart beats. This technique forms the basis of functional assessment by CMR. Blood typically appears bright in these sequences due to the contrast properties of blood and its rapid flow. The technique can discrimate very well between blood and myocardium. The current technique typically used for this is called
balanced steady state free precession (SSFP), implemented as TrueFISP, b-FFE or Fiesta, depending on scanner manufacturer.

A 4 chamber view of the heart using SSFP cine imaging. Compare the image orientation (4 chamber) with the short axis view of the movie above

Infarct imaging using contrast

Scar is best seen after giving a contrast agent, typically one containing gadolinium bound to DTPA. With a special sequence, Inversion Recovery (IR) normal heart muscle appears dark, whilst areas of infarction appear bright white.

CMR in the 4 chamber view comparing the cine (left) with the late gadolinium image using inversion recovery (right). The subendocardial infarct is clearly seen. Fat around the heart also appears white.


In angina, the heart muscle is starved of oxygen by a coronary artery narrowing, especially during stress. This appears as a transient perfusion defect when a dose of contrast is given into a vein. Knowing whether a perfusion defect is present and where it is helps guide intervention and treatment for coronary artery narrowings.

CMR perfusion. Contrast appears in the right ventricle then left ventricle before blushing into the muscle, which is normal (left) and abnormal (right, an inferior perfusion defect).

Current applications of CMR

In the investigation of cardiovascular disease the physician has a wide variety of tools available. The key disadvantages of CMR are limited availability, expense, operator dependence and a lack of outcome data. The key advantages are image quality, non-invasiveness, accuracy, versatility and no ionising radiation. A good list of current CMR indications can be found [ here]

Case examples of the use of CMR

For online case examples, see [ here]

pecific clinical uses of CMR

A good overview of the clinical indications for CMR can be found [ here] and [ here]

Centres performing CMR

Training in CMR

Training is being increasingly protocolised and is now formal with stages of training and accreditation. Internationally approved training guidelines can be found [ here] A resource for anyone thinking about CMR as a career can be found [ here]

What it is like having a CMR scan

A good description of the experience of receieving a CMR can be found [ here]

Manufacturers of CMR scanners

[ GE Healthcare]

[ Philips medical systems]

[ Siemens medical solutions, Inc]

External links

* [ The Society for Cardiovascular Magnetic Resonance]
* [ An Atlas of normal cardiac structure and function by CMR]
* [ Having a CMR scan]

Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Magnetic resonance imaging — MRI redirects here. For other meanings of MRI or Mri, see MRI (disambiguation). Magnetic resonance imaging Intervention Sagittal MR image of the knee ICD 10 PCS B?3?ZZZ …   Wikipedia

  • Imagerie par résonance magnétique — Pour les articles homonymes, voir IRM et MRI. L imagerie par résonance magnétique (IRM) est une technique d imagerie médicale permettant d obtenir des vues 2D ou 3D de l intérieur du corps de façon non invasive avec une résolution relativement… …   Wikipédia en Français

  • Libin Cardiovascular Institute of Alberta — The Libin Cardiovascular Institute of Alberta is a partnership between the Calgary Health Region and the University of Calgary. Its mandate comprises all cardiovascular research, education and service delivery, with a service area extending from… …   Wikipedia

  • human cardiovascular system — ▪ anatomy Introduction       organ system that conveys blood through vessels to and from all parts of the body, carrying nutrients and oxygen to tissues and removing carbon dioxide and other wastes. It is a closed tubular system in which the… …   Universalium

  • Cardiac output — (Q or or CO ) is the volume of blood being pumped by the heart, in particular by a left or right ventricle in the time interval of one minute. CO may be measured in many ways, for example dm3/min (1 dm3 equals 1000 cm3 or 1 litre). Q is… …   Wikipedia

  • Fast Low-Angle Shot — Der englischsprachige Begriff Fast Low Angle Shot (FLASH) bezeichnet in der Medizin ein 1985 von Jens Frahm, Axel Haase, Wolfgang Hänicke, Klaus Dietmar Merboldt und Dieter Matthaei eingeführtes Verfahren zur schnellen Bildgebung auf der… …   Deutsch Wikipedia

  • Myocarditis — Classification and external resources Histopathological image of myocarditis at autopsy in a patient with acute onset of congestive heart failure. ICD 10 I …   Wikipedia

  • Communication inter-ventriculaire — Pour les articles homonymes, voir CIV. Cœur normal …   Wikipédia en Français

  • Morbus Fabry — Klassifikation nach ICD 10 E75.2 Sonstige Sphingolipidosen (inkl. Fabry (Anderson )Krankheit) …   Deutsch Wikipedia

  • Echtzeit-MRT — Die Echtzeit Magnetresonanztomographie (Echtzeit MRT) (auch MR Fluoroskopie) ist ein Verfahren auf der Grundlage der Magnetresonanztomographie für die kontinuierliche Beobachtung eines bewegten Objektes in Echtzeit, also für die Darstellung einer …   Deutsch Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”