Harmonizing SUVs in multicentre trials when using different generation PET systems: prospective validation in non-small cell lung cancer patients

Abstract

Purpose

We prospectively evaluated whether a strategy using point spread function (PSF) reconstruction for both diagnostic and quantitative analysis in non-small cell lung cancer (NSCLC) patients meets the European Association of Nuclear Medicine (EANM) guidelines for harmonization of quantitative values.

Methods

The NEMA NU-2 phantom was used to determine the optimal filter to apply to PSF-reconstructed images in order to obtain recovery coefficients (RCs) fulfilling the EANM guidelines for tumour positron emission tomography (PET) imaging (PSF _EANM). PET data of 52 consecutive NSCLC patients were reconstructed with unfiltered PSF reconstruction (PSF _allpass), PSF _EANM and with a conventional ordered subset expectation maximization (OSEM) algorithm known to meet EANM guidelines. To mimic a situation in which a patient would undergo pre- and post-therapy PET scans on different generation PET systems, standardized uptake values (SUVs) for OSEM reconstruction were compared to SUVs for PSF _EANM and PSF _allpass reconstruction.

Results

Overall, in 195 lesions, Bland-Altman analysis demonstrated that the mean ratio between PSF _EANM and OSEM data was 1.03 [95 % confidence interval (CI) 0.94–1.12] and 1.02 (95 % CI 0.90–1.14) for SUV _max and SUV _mean, respectively. No difference was noticed when analysing lesions based on their size and location or on patient body habitus and image noise. Ten patients (84 lesions) underwent two PET scans for response monitoring. Using the European Organization for Research and Treatment of Cancer (EORTC) criteria, there was an almost perfect agreement between OSEM _PET1/OSEM _PET2 (current standard) and OSEM _PET1/PSF _EANM-PET2 or PSF _EANM-PET1/OSEM _PET2 with kappa values of 0.95 (95 % CI 0.91–1.00) and 0.99 (95 % CI 0.96–1.00), respectively. The use of PSF _allpass either for pre- or post-treatment (i.e. OSEM _PET1/PSF _allpass-PET2 or PSF _allpass-PET1/OSEM _PET2) showed considerably less agreement with kappa values of 0.75 (95 % CI 0.67–0.83) and 0.86 (95 % CI 0.78–0.94), respectively.

Conclusion

Protocol-optimized images and compliance with EANM guidelines allowed for a reliable pre- and post-therapy evaluation when using different generation PET systems. These data obtained in NSCLC patients could be extrapolated to other solid tumours.

Electronic supplementary material

The online version of this article (doi:10.1007/s00259-013-2391-1) contains supplementary material, which is available to authorized users.