Stage with FDG PET-CT by the Lugano classification (nodal regions above and below the diaphragm, extranodal sites, bulk), then assess response with the Deauville five-point scale against the mediastinum and liver.
Orient first
- Most lymphomas are FDG-avid and are staged and response-assessed with PET-CT; some subtypes are variably avid and use CT criteria.
- Lugano staging: I–II limited (one side of the diaphragm), III–IV advanced; bulk is recorded by the longest diameter — verify the bulk threshold for the histology.
- Deauville: 1 no uptake, 2 at or below mediastinum, 3 above mediastinum but at or below liver, 4 moderately above liver, 5 markedly above liver or new lesions.
Acquire the study
- FDG PET-CT with a diagnostic or low-dose CT; standardised uptake time and fasting.
The manoeuvre
- Nodal regions on each side of the diaphragm: avid nodes, their size on the CT component in mm.
- Extranodal disease: spleen (diffuse or focal uptake), liver, bone marrow (focal uptake), lung, gut.
- Bulk: longest diameter of the largest mass in cm.
- Reference regions for response: mediastinal blood pool and liver SUV.
- Deauville score of the most avid residual lesion at interim and end of treatment, compared with baseline.
What confirms it
- A Lugano stage with bulk recorded at baseline; a Deauville score at each response scan.
What licenses you to exclude it
- A Deauville 1–3 at end of treatment is a complete metabolic response in most FDG-avid lymphomas (context and trial rules can differ).
The classic misread
- Scoring diffuse marrow uptake after growth factors, or thymic rebound in young patients, as disease.