The British journal of radiology 2017 12 15() 20170774 doi 10.1259/bjr.20170774
Focal incidental uptake, with or without CT abnormalities, is a common finding on FDG PET/CT and evidence based management for this type of uptake is lacking. This article reviews the evidence on focal incidental uptake including the incidence of malignancy, differential diagnosis and imaging criteria which can be used to further characterise it. The article focusses on PET rather than CT criteria. The strength of the evidence base is highly variable ranging from systematic reviews and meta-analyses to a virtual absence of evidence. Caution needs to be used when using SUVs reported in other studies due to inter-patient and institution observed variation in SUVs. There is sufficient evidence to permit specific suggestions on how to interpret the foci and recommend further management in the: pituitary (investigate when SUVmax > 4.1), thyroid (investigate all), breast (investigate all), lung parenchyma (if focus of FDG without a CT nodule no further investigations), colon (investigate all foci with SUVmax >5.9 , urgently if SUVmax > 11.4), adrenals (criteria depend on if patient has cancer) and prostate gland (investigate in men aged > 50 years or >40 years if peripheral uptake or patient has other risk factors). There is some evidence to guide further management for the parotid gland, naso-orophaynx, oesophagus, pancreas, uterus and ovaries. There is insufficient evidence to guide management for the liver, spleen, kidneys, gallbladder, testis and bone, for these organs patient characteristics and other guidelines will likely be of more use in determining further management.