Definition of SUVmax
SUVmax (maximum standardized uptake value) is a quantitative measure representing the single voxel with the highest radiotracer uptake within a lesion on PET imaging, most commonly used with FDG-PET/CT to assess tumor metabolic activity.
Technical Definition
SUVmax represents the measure of the single whole voxel in a particular lesion with highest/maximum uptake 1. The maximum uptake must be defined on original reconstructed PET images—no additional rebinning, resampling, smoothing, or any other manipulation by the user is allowed 1.
Calculation Formula
The standardized uptake value is calculated as:
SUV = (radiotracer uptake in μCi/ml tissue as determined from PET image) / (total injected radiotracer activity in μCi/g body mass) 2
This is also referred to as SUVbm when normalized to total body mass.
Key Characteristics
- Single voxel measurement: Unlike SUVmean or SUVpeak, SUVmax captures only the most metabolically active single voxel within a region of interest
- No spatial averaging: It does not average uptake across multiple voxels
- Highly reproducible: When proper acquisition protocols are followed per EANM or UPICT standards 1
Clinical Context
SUVmax is widely used in oncologic imaging to:
- Assess tumor aggressiveness 3, 4
- Predict prognosis in various malignancies 4, 5
- Evaluate treatment response
- Distinguish benign from malignant lesions
Important Caveats
SUVmax is sensitive to body weight changes, which can lead to inaccuracies in patients with cancer cachexia or obesity 3. For this reason, SULmax (SUV normalized to lean body mass) may be preferred in patients with significant weight fluctuations, though both metrics perform similarly in most clinical scenarios 3.
The metric requires standardized acquisition protocols including consistent uptake time (typically 60 minutes post-injection), patient preparation, and scanner calibration 1, 2.