Clearance determination methods

There are several principles which can be used for clearance determination, and a number of different methods are applied under each principle, some of them dependent on the radiopharmaceutical used. A large variety of different algorithms, which were determined empirically, are available for methods employed in clinical routine. Experts seldom agree on their usefulness and accuracy, and they are employed to different extents depending on the country. This review article presents the physiological basics of clearance determination and gives a short overview of the radiopharmaceuticals used as well as showing the theoretical background of the respective clearance determination methods. The paper focuses on the author's modification of the single-sample method, which has been known since the 1970's. The resulting new algorithms are meanwhile widely used especially in Germany, which is a considerable contribution to the standardization of clearance results using 99mTc-MAG3. Furthermore, a selection of suitable algorithms for the use of different clearance substances is offered. A further, essential aspect of renal diagnostics in nuclear medicine is described in detail: The calculation of the split clearance using a method implemented in the software of most camera manufacturers. (orig.)