Conventional echocardiography is performed from the anterior chest wall (precordium) and is known as transthoracic echo. Echocardiography can also be performed from the oesophagus which is known as transoesophageal echo. Standard positions on the chest wall are used for placement of the transducer which are called echo windows. These are left parasternal, apical, sub-costal, right parasternal, and suprasternal. During echocardiography, a balance has to be struck between tissue penetration and image resolution. Low frequency transducers used for transthoracic echo have good penetration (less attenuation) but relatively poor resolution. On the other hand, high frequency transducers have poor penetration (more attenuation) but better resolution. The oesophagus provides an opportunity to examine the heart and related structures with a high frequency transducer positioned in the oesophagus for better image resolution. Techniques are also being developed to improve assessment of myocardial perfusion, viability and function by use of sonicated radiographic contrast materials. Coronory flow can then be estimated by time-intensity curves of sonodensity.