Tumor size on computed tomography scans - Is one measurement enough?

BACKGROUND. Bidimensional tumor measurements are used routinely as surrogat es for tumor volume. The purpose this study was to determine whether there is any added benefit in bidimensional or tridimensional measurements over a unidimensional measurement. METHODS. Sixty-nine colorectal hepatic metastases on 19 computed tomography scans (1-8 lesions per scan) from 9 patients were analyzed. Five patients contributed 2-4 scans each (mean, 3 scans). The standard Volume of these le sions was determined by the "summation of areas" technique. The maximum axi al dimension, the product of the greatest axial dimensions, and several vol ume estimates (based on the volumes of a sphere, an ellipsoid, and a cube) each were correlated with the standard volume. RESULTS. The maximum axial dimension and the product of the greatest axial dimensions correlated equally with tumor volume (correlation coefficient = 0.93). Surrogate measures based on the equations for a sphere and an ellips oid underestimated tumor volume, whereas the equation for a cube overestima ted volume. CONCLUSIONS. When reporting tumor size, there is no significant added benef it in reporting bidimensional or tridimensional measurements over the maxim um axial dimension. (C) 2001 American Cancer Society.