Tumor volume-adapted SUV as an alternative to SUV for quantification of small lesions in PET/CT imaging: a proof-of-concept study.

PURPOSE

SUV is a recommended quantification metric except for small lesions. We aimed to assess the averaged standard uptake value (SUV) as an alternative to SUV for small-lesion quantification.

MATERIALS AND METHODS

NEMA-like phantom images were reconstructed using OSEM, OSEM + PSF, OSEM + TOF and OSEM + TOF + PSF with two post-smoothing Gaussian filters for different background activity levels. SUV, SUV (N = 5, 10, 15, 20, 25, 30, 35 or 40 hottest voxels), and SUV, relative percent error, contrast recovery, and volume recovery coefficients were quantified and assessed.

RESULTS

SUV did not have the limitations of SUV for smaller lesions. In the smallest insert at 2.68 kBq/ml, optimum N values for OSEM, OSEM + PSF, OSEM + TOF and OSEM + TOF + PSF were 10, 5, 15, and 10 for SUV, respectively. The same N values were obtained for metabolic tumor volumes (MTVs) for all reconstruction algorithms. At 5.30 kBq/ml, N = 5 was optimum for SUV and MTVs. For the larger inserts, the optimum N increased and tended towards the maximum (similar to SUV).

CONCLUSIONS

SUV is more accurate than SUV or SUV for small lesions, while being as accurate in larger ones. This harmonizing capacity of SUV can be beneficial for the quantitative analysis of small tumor volumes.