Does whole-body Patlak 18F-FDG PET imaging improve lesion detectability in clinical oncology?
PURPOSE: Single-pass whole-body (WB) 18F-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 18F-FDG influx rate constant Ki, as a complement to standard-of-care standardized uptake value (SUV) imaging for a range of oncologic studies. METHODS: We compared SUV and Ki 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, Kimean, Kimax, 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 Ki images. One proven malignant lesion was detected only on Ki images whereas none of the proven malignant lesions was visible only on SUV images. The proven malignant lesions had overall higher Ki 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 Ki over SUV imaging. CONCLUSION: Oncologic WB Patlak Ki 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 18 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 18 F-FDG uptake relative to SUV. • Parametric imaging may achieve equivalent or superior 18 F-FDG lesion detectability than standard-of-care SUV imaging in oncology.