Does whole-body Patlak F-FDG PET imaging improve lesion detectability in clinical oncology?

PURPOSE: Single-pass whole-body (WB) F-FDG PET/CT imaging is routinely employed for the clinical assessment of malignant, infectious, and inflammatory diseases. Our aim in this study is the systematic clinical assessment of lesion detectability in multi-pass WB parametric imaging enabling direct imaging of the highly quantitative F-FDG influx rate constant K, as a complement to standard-of-care standardized uptake value (SUV) imaging for a range of oncologic studies.

METHODS: We compared SUV and K images of 18 clinical studies of different oncologic indications (lesion characterization and staging) including standard-of-care SUV and dynamic WB PET protocols in a single session. The comparison involved both the visual assessment and the quantitative evaluation of SUV, SUV, K, K, tumor-to-background ratio (TBR, TBR), and contrast-to-noise ratio (CNR, CNR) quality metrics.

RESULTS: Overall, both methods provided good-quality images suitable for visual interpretation. A total of 118 lesions were detected, including 40 malignant (proven) and 78 malignant (unproven) lesions. Of those, 111 were detected on SUV and 108 on K images. One proven malignant lesion was detected only on K images whereas none of the proven malignant lesions was visible only on SUV images. The proven malignant lesions had overall higher K TBR and CNR scores. One unproven lesion, which was later confirmed as benign, was detected only on the SUV images (false-positive). Overall, our results from 40 proven malignant lesions suggested improved sensitivity (from 92.5 to 95%) and accuracy (from 90.24 to 95.12%) and potentially enhanced specificity with K over SUV imaging.

CONCLUSION: Oncologic WB Patlak K imaging may achieve equivalent or superior lesion detectability with reduced false-positive rates when complementing standard-of-care SUV imaging.

KEY POINTS: • The whole-body spatio-temporal distribution of F-FDG uptake may reveal clinically useful information on oncologic diseases to complement the standard-of-care SUV metric. • Parametric imaging resulted in less false-positive indications of non-specific F-FDG uptake relative to SUV. • Parametric imaging may achieve equivalent or superior F-FDG lesion detectability than standard-of-care SUV imaging in oncology.