REQUIREMENTS AND IMPLEMENTATION OF A FLEXIBLE KINETIC MODELING TOOL

Kinetic (or compartment) modeling is a highly versatile tool for the a nalysis of experiments within living systems. In PET, it is essential for developing tracers, for assessing tracer behavior and for extracti ng quantitative information about the target process. However, tools t o support the modeling tasks involved are not easily available. Method s: This article presents a requirements analysis for kinetic modeling in PET. The interactive kinetic modeling tool KMZ implements many of t hese features. It facilitates model development by a set of predefined models and by the ease of introducing new models. Monte Carlo studies allow assessing parameter identifiability. The responses in the diffe rent compartments as well as the expected time-activity curve can be s imulated for specific model configurations. For measured time-activity curves, model optimization can be performed by the Powell or the Marq uardt algorithm. Both support weighted nonlinear least-squares fitting and allow optional constraints of parameter ranges. To further improv e parameter estimation, the fitting of several regional time-activity curves can be coupled, resulting in lower standard errors for paramete rs common among regions. It is possible to highly automate the evaluat ion of study series and to forward the results into statistical analys is tools. Results: The KMZ tool has proven highly suitable in evaluati ng data from different types of studies, and the intuitive user interf ace enables medical doctors to successfully perform routine evaluation s after a short training period. Conclusion: A portable kinetic modeli ng tool with the described features would provide easy access to model development and may help consolidate kinetic modeling in clinical set tings for well-defined applications.