Measuring lesion growth from 3D medical images

Evaluating precisely the temporal variations of lesion volumes is very important for at least three types of practical applications: pharmaceutical trials, decision making for drug treatment or surgery and patient follow-up. The authors present a volumetric analysis technique, combining precise rigid registration of 3D medical images, nonrigid deformation computation and flowfield analysis. Their analysis technique has two outcomes: the detection of evolving lesions and the quantitative measurement of volume variations. The originality of their approach is that no precise segmentation of the lesion is needed but the approximative designation of a region of interest, which can be automatized. They distinguish between tissue transformation (image intensity changes without deformation) and expansion or contraction effects reflecting a change of mass within the tissue; a real lesion being generally the combination of both effects. The method is tested with synthesized 3D image sequences and applied, in a first attempt to quantify in vivo a mass effect, to the analysis of a patient with multiple sclerosis (MS).