The cardiothoracic ratio--an inaccurate and outdated measurement: new data from CT.

Cardiomegaly (and left ventricular size in particular) is well recognized to have cardiovascular prognostic significance. Cardiac assessment should be routinely performed when evaluating imaging studies encompassing the thorax, whether cross sectional or projectional. However, such measurements should be robust, readily available and practical. In this issue of European Radiology, Schlett et al. describe such a technique based on single level area and transverse diameter measurements on transverse CT and projection digitally acquired radiographs. This paper is significant as it makes a simple tool for left ventricular assessment readily available to all cross-sectional imagers and highlights the established limitation of cardiothoracic ratio on the chest radiograph.