The quantification with FDG as seen by a physician.

Although, at the present, in the routine practice, the qualitative analysis of PET with F-18 Fluoro-deoxyglucose (FDG) remains indispensable and sufficient for clinical purposes, a quantitative approach may add a significant contribution, when rigorous and reliable. In particular, a quantitative analysis may already be clinically applied for indications as a better definition of a specificity's threshold, a more precise prognostic stratification, a correct evaluation of the tumor response and/or of the disease's evolution. The cost/effectiveness of this approach may be found in better defining diagnostic and therapeutic strategies. Conversely to be applied in the clinical practice the method has to be as easy as possible. Therefore the final goal is to apply the simplest method to allow a reliable quantitative evaluation. To arrive to this result, applicable using simplified methods hopefully including also repeated static images, it is important to validate the new procedures versus the already verified more rigorous and precise measurements. Being acceptable in the clinical practice a lower precision with respect to the one required in the research, it is mandatory to avoid problems to the patient, as those connected with an intra-arterial sampling. Similarly cannot be applied in the routine a procedure too long or requiring overmuch expertise and performing tools, therefore non diffusible for a clinical use. The goal of this review is to suggest, from the point of view of a physician, which are at the present the simplified methods that could be easily and widely applied in the clinical practice for a reliable quantification with FDG.