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Functional magnetic resonance imaging (fMRI) is a medical imaging modality that indirectly measures neural activity by observing the local hemodynamics, or blood oxygen level dependent signal (BOLD). fMRI data offers a range of insights, and can be roughly divided into two categories:
Gated SPECT is a nuclear medicine imaging technique, typically for the heart in myocardial perfusion imagery. [1] An electrocardiogram (ECG) guides the image acquisition, and the resulting set of single-photon emission computed tomography (SPECT) images shows the heart as it contracts over the interval from one R wave to the next.
Imaging of the cardiovascular system is usually performed with cardiac gating using an adaptation of conventional ECG techniques. [19] Cine sequences of the heart are acquired using balanced steady state free precession (bSSFP) which has good temporal resolution and intrinsic image contrast. T1-weighted sequences are used to visualize anatomy ...
A tagged MRI showing motion of a human heart is shown in the image (a). The effect of tagging can be described as a multiplication of the underlying image by a sinusoid tag pattern having a certain fundamental frequency, causing an amplitude modulation of the underlying image and replicating its Fourier transform into the pattern shown in (b).
A physician may recommend cardiac imaging to support a diagnosis of a heart condition. Medical specialty professional organizations discourage the use of routine cardiac imaging during pre-operative assessment for patients about to undergo low or mid-risk non-cardiac surgery because the procedure carries risks and is unlikely to result in the change of a patient's management. [1]
Cardiac magnetic resonance imaging perfusion (cardiac MRI perfusion, CMRI perfusion), also known as stress CMR perfusion, [1] is a clinical magnetic resonance imaging test performed on patients with known or suspected coronary artery disease to determine if there are perfusion defects in the myocardium of the left ventricle that are caused by narrowing of one or more of the coronary arteries.
Heart signals were indeed seen, but were very noisy. The next development was by David Cohen , [ 2 ] who used a magnetically shielded room to reduce the background, and a smaller coil with better electronics; the heart signals were now less noisy, allowing a magnetic map to be made, verifying the magnetic properties and source of the signal.
Radionuclide angiography is an area of nuclear medicine which specialises in imaging to show the functionality of the right and left ventricles of the heart, thus allowing informed diagnostic intervention in heart failure. It involves use of a radiopharmaceutical, injected into a patient, and a gamma camera for acquisition.