Does whole-body Patlak 18F-FDG PET imaging improve lesion detectability in clinical oncology?

Purpose Single-pass whole-body (WB) F-18-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-18-FDG influx rate constant K-i, as a complement to standard-of-care standardized uptake value (SUV) imaging for a range of oncologic studies. Methods We compared SUV and K-i 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 SUVmean, SUVmax, K-imean, K-imax, tumor-to-background ratio (TBRSUV, TBRKi), and contrast-to-noise ratio (CNRSUV, CNRKi) 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-i images. One proven malignant lesion was detected only on K-i images whereas none of the proven malignant lesions was visible only on SUV images. The proven malignant lesions had overall higher K-i 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-i over SUV imaging. Conclusion Oncologic WB Patlak K-i imaging may achieve equivalent or superior lesion detectability with reduced false-positive rates when complementing standard-of-care SUV imaging.