Radiographic determination of cardiomegaly using cardiothoracic ratio and transverse cardiac diameter: can one size fit all? Part one.

Introduction: The cardio-thoracic ratio (CTR) and the transverse cardiac diameter (TCD) on Plain chest radiography are the two parameters commonly used to diagnose cardiomegaly and heart disease. A CTR of greater than 50% on a PA film is abnormal and normally indicates cardiac or pericardial disease condition, whiles an increase of TCD from 1.5 to 2cm on two consecutive radiographs, taken at short interval, suggests possible cardiac pathology.