A number of techniques are used to diagnose blocks
in the arteries supplying to the heart. These techniques help the cardiologist
decide if the person requires angioplasty. Coronary angiography, in which a dye
is injected into the coronary arteries, is a procedure that checks the
structure of the blood vessels supplying to the heart. Some of the newer
techniques are designed to test the function of the heart. These include SPECT
single-photon emission computed tomography is a procedure in which the patient
is administered a radioactive substance though an injection
. The radioactive substance
moves along the blood flow. Images are then taken with a special camera. Areas
with reduced blood flow are thus detected. The disadvantages of this procedure
are varying degrees of accuracy and exposure of the patient to radiation.
magnetic resonance or CMR, also known as cardiac MRI, is another new technique
that may be used as an alternative to SPECT
. Like other MRIs, it produces a powerful
magnetic field to study the heart. It has the advantage that it does not expose
the patient to radiation. It can detect multiple problems of the heart during a
single examination including those affecting the heart muscles or the blood
vessels supplying to the heart.
A recent study
compared the sensitivity of SPECT and CMR in angina patients requiring a
The patients underwent the procedures of x-ray coronary angiography,
SPECT and CMR.
The study found that CMR was more sensitive in
diagnosing clinically significant heart disease in suspected cases of angina as
compared to SPECT. CMR however is not useful in patients with claustrophobia,
wide abdominal girth and presence of medical implants.
The study thus
suggests that CMR is superior to SPECT in diagnosing problems related to a
reduction in blood flow to the heart, and should be used more often
. However, the costs of the
procedure should also be considered while opting for a particular procedure.
1. Cardiovascular magnetic resonance and single-photon emission computed
tomography for diagnosis of coronary heart disease (CE-MARC): a prospective
trial; Dr. John Greenwood et al; The Lancet, Volume 379, Issue 9814, Pages 453