| Measurability of lesion at baseline | 1. 18F-FDG–avid | 1. 18F-FDG–avid tumor; baseline PET scan is desirable |
| 2. Standardized display with normalization to liver | 2. Variably 18F-FDG–avid tumor; 18F-FDG baseline PET scan is required |
| | 3. Follow-up PET at least 3 wk after last chemotherapy session or at least 8–12 wk after last radiation therapy session |
| Objective response | Complete metabolic response: 18F-FDG–avid lesions revert to background of normal tissues in which they are located | Complete response in 18F-FDG–avid tumors: no focal or diffuse increased 18F-FDG uptake over background in location consistent with tumor, regardless of CT abnormality; new lung nodules in lymphoma patient without history of lung involvement (regardless of 18F-FDG avidity) are not considered lymphoma; increased focal or multifocal marrow uptake is not considered tumor unless biopsy is done |
| Partial metabolic response: “significant reduction in SUV in tumors” | Noncomplete response: diffuse or focal uptake exceeding mediastinal blood pool if >2 cm in size; in nodes < 2 cm diameter, uptake of 18F-FDG greater than background is positive; lesions > 1.5 cm in size in liver or spleen with uptake equal to or greater than spleen are considered tumor |
| SMD: “no visible change in metabolic activity of tumors” | Partial remission: see Table 3 |
| Progressive metabolic disease: “increase in intensity or extent of tumor metabolic activity or new sites” | Progressive disease: see Table 3 |