A patient with known lymphoma undergoes PET-CT after 4 cycles of chemotherapy. A residual mediastinal mass is present but shows no FDG uptake (SUVmax 1.8, same as background). According to the Deauville 5-point scale, this lesion scores:

• A Deauville 3 — partial metabolic response
• B Deauville 4 — partial metabolic response with residual disease
• C Deauville 2 — complete metabolic response ✓
• D Deauville 5 — progressive disease

Explanation

The Deauville scale: 1 = no uptake; 2 = uptake ≤ mediastinum; 3 = uptake > mediastinum but ≤ liver; 4 = uptake moderately > liver; 5 = markedly > liver or new lesions. An SUVmax equal to background (mediastinum blood pool ~2.0) falls at Deauville 2, indicating complete metabolic response (CMR). CMR (scores 1–2) predicts excellent prognosis. Score 3 is equivocal. Scores 4–5 indicate inadequate response.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.