Table 1.

Criteria for visual assessment of ¹⁸F-FDG PET/CT applied to distinguish lesions as most likely positive or ambiguous/unclear

Attribute	Criteria
Form	Most likely positive: round/nodular shape, regular or irregular; ambiguous/unclear: apparently round, but not perfectly defined because of small dimensions or too close to other lesions
Dimension	Most likely positive: ≥1 cm; ambiguous/unclear: 0.9–0.99 cm
Location	Most likely positive: sites normally involved in metastatic process, with optimal contrast between the lesion and its immediate surroundings (see also Table 2); ambiguous/unclear: sites normally involved in metastatic process, with suboptimal contrast between the lesion and its immediate surroundings
SUVmax	Both most likely positive and ambiguous: ≥2.5
Other attributes considered	Correlation with patient history; comparison with other imaging modalities; physical examination