? Head-to-head intra-individual comparison of 18F-FDG total-body PET/CT and conventional digital PET/CT in patients with malignance tumor: how sensitive could it be?

Introduction: This study aims to investigate the sensitivity of the ¹⁸F-FDG total-body (TB) PET/CT and a conventional digital PET/CT using a head-to-head comparison with the pathological findings as reference.

Methods: The prospective study was conducted on 125 consecutive patients who underwent a TB PET/CT scan and a conventional digital PET/CT scan in random sequence after a single ¹⁸F-FDG injection (3.7MBq/kg). Finally, 67 patients (median age, 65 years; 24 female and 43 male patients) were enrolled in this study. PET raw data of TB PET/CT were acquired within 5 min and reconstructed using data from the first 1, 2, 3, 4, and 5 min (G1, G2, G3, G4, G5). The images of conventional digital PET/CT were referred to as G0. Two nuclear medicine physicians independently assessed subjective image quality using a 5-point Likert scale and interpreted images for staging. Objective image quality and lesions characteristics were measured and compared with G0. Sub-analysis on regional lymphocytes was also performed.

Results: A total of 241 lesions (69 primary lesions; 140 local lymphocyte metastases; 32 distal metastases) of 67 patients&nbsp;with ten types of cancer,&nbsp;proved by pathology, were analyzed. The subjective image quality score and SNR increased gradually from G1 to G5, significantly higher than G0 (all&nbsp;p&nbsp;< 0.05). In addition, G4 and G5 of TB PET/CT detected additional 13 lesions (2 primary lesions; 6 lymphocyte metastases; 5 distant lesions) and&nbsp;enabled correct treatment recommendations for six patients&nbsp;(6/67?9.0%)&nbsp;compared with&nbsp;conventional&nbsp;PET/CT.

Conclusions: This study showed that 4-min acquisition in TB PET/CT using regular dose is&nbsp;appreciated for optimal detection efficiency in various lesions, including small and low-uptake lesions. And&nbsp;TB PET/CT enables more appropriate management than conventional digital PET/CT for detecting more lesions as well as higher image quality.