Quantification in Nuclear Medicine Imaging

Nuclear Medicine imaging is based on tracing a radioactive labelled biomolecule (aka tracer) specific to a functional process within a living organism. This enables an assessment of the underlying functional or metabolic processes non-invasive. Such an evaluation can be done qualitatively, for example by visually assessing areas of enhanced metabolism or it can be done quantitatively However, multiple ways of quantification in nuclear medicine exist; Rather simple methods are based on comparing the tracer uptake in a target region with the uptake in a reference organ or with physiological uptake in a normal control group. More advanced methods are based on the ratio of tracer uptake in a target region with a surrogate of available tracer (e.g. the standardized uptake value – SUV in positron emission tomography) and full quantitative approaches make use of models of the underlying functional or metabolic process which are fitted to dynamic data. Yet, all of these quantification approaches have their advantages and disadvantages; the simple methods often fall short in terms of quantitative accuracy while full kinetic modelling usually requires long and complicated examination protocols and extensive post-processing of the data. Therefore, the selection of a quantitative metric to assess a specific process is often task specific and new- and improved methods are under current development. For example, fully automated kinetic modelling pipelines have been suggested, direct kinetic reconstruction techniques incorporating the functional models in the image reconstruction are available and new imaging protocols based on constant tracer infusions have been introduced. Further, standardization and harmonization efforts have been taken to improve the comparability of data across imaging systems and centres.

In this research topic we seek to collect articles dealing with quantification approaches in Nuclear Medicine. Among others, this includes assessments and improvements of the quantitative accuracy of the Nuclear Medicine imaging systems, the use of quantitative measures and their improvement in clinical and preclinical applications and new concepts to assess functional parameters. Further, review articles concerning the topic of quantification in nuclear medicine and articles on standardization and harmonization approaches are welcome as well.