NUCLEAR MEDICINE:

Nuclear Medicine has got a tremendous role in cardiac imaging. In fact it is complementary to Coronary Angiography in the assessment of haemodynamically significant lesions which is helpful in the therapeutic  decision making . The department of Nuclear Medicine is equipped with advanced state of the art Siemens Symbia Dual Head SPECT Gamma Camera. Nuclear Medicine studies use small doses of radioactive material to assess myocardial blood flow , evaluate the pumping function of the heart  as well as visualization of location of a heart attack. The main investigations carried out in nuclear medicine:

Cardiac Tests  (95% of cases)

1. Myocardial Perfusion Imaging (MPI)
   1. Rest – Redistribution study
   2. Stress Myocardial perfusion Scintigraphy.

2. Rest-Muga Radionuclide Ventriculography

Non Cardiac Tests

(5% of cases)

1. Renal Dynamic Study
2. Lung Perfusion Imaging
3. Thyroid scans
4. Whole body bone scans

The Role of Myocardial Perfusion Scintigraphy is useful in :

• Diagnosis of Coronary artery disease (CAD) and various cardiac abnormalities.
• Identifying location, criticality of existing coronary stenosis and degree of coronary artery disease (CAD) in patients with a history of CAD.
• Prognostication (risk stratification) and evaluation of patients that are at risk of having a myocardial or coronary incident. (ex: myocardial infarction, myocardial ischemia, coronary aneurysm, wall motion abnormalities)
• Assessment of viable myocardium in particular coronary artery territory following heart attacks to justify revascularization
• Post intervention revascularization (coronary artery bypass graft /angioplasty) evaluation of heart.

A stress Myocardial Perfusion imaging is used to assess the regional blood flow of the heart muscle both at stress and rest and the comparision of both the images helps in assessment of heart attacks as well as the inducible ischaemia . It also helps in prognostication and assessment of future cardiac events . It is also used in the detection of homodynamic significance of  coronary artery disease as assessed on a coronary angiography/ 64 slice CT. It also helps in pre-discharge evaluation and assess  the future risks . Also it is helpful in post intervention evaluation.

A rest MUGA imaging is the blood pool imaging of the heart and is helpful in the Evaluation of Left & Right ventricular Ejection Fractions (Pumping Function Of The Heart as  well as the ventricular wall motion abnormalities.

There are two gamma cameras installed. The installation of new top of the line gamma camera from GE (Discovery NM 530c), which is only the second in the country, has made significant improvements in the Nuclear Myocardial perfusion imaging. It is a cardiac dedicated camera which is based on the semiconductor technology of cadmium zinc tellurium (CZT) detectors and stationary acquisition which uses Alcyone technology. This technology incorporates four innovations :Solid State Detector Technology , Stationary acquisition Focused collimation & Topographic Reconstruction. The combination of these four innovations results into improved energy and spatial resolution, high sensitivity and provides clear images and reduces the probability of artifacts and thus can potentially translate into clinical values not seen today with the current technology.

 It has got a large number of advantages over the conventional gamma camera:

• Superior technology including superior processing tools which helps in
  • Improved image quality and reduces the probability of artifacts.
  • Shorter acquisition time improves patient comfort.
  • Stationary acquisition provides full volume scans with no moving parts.
• Reduction in quantity of dose administered which reduces the radiation exposure to the patients.
• It also reduces the scanning time to half thus significantly reducing the test time.
• Fast preparation of report because of improved processing software.
• The imaging can be done even in semi supine position which is beneficial to the patients who can’t lie down properly because of left ventricular failure
• A claustrophobic patient can also undergo imaging with ease because of its configuration (C shaped).