What Percentage Change In SUV is “Clinically Significant” on a Follow Up Exam?

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If SUV is so easily influenced by external factors (addressed in detail, here), does a 5% or 10% or 20% change in a lesion’s SUV on a subsequent exam more likely reflect an alteration in the tumor’s intrinsic metabolic activity, or does it simply reflect a normal and expected variation intrinsic to the SUV formula?

A growing consensus strongly cautions against interpreting as “clinically significant” any SUV change less than 25-30%.

Moreover, before calling a 25-30% change “significant”, one must be sure there are not other visible signs on the study that might account for the significant difference in SUV (addressed in detail, here).

To put this in perspective, an intensely FDG-avid liver mass that decreases in SUV from 7.1 to 5.4 (24%) may actually represent no change at all.