PET/CT-guided percutaneous liver mass biopsies and ablations: targeting accuracy of a single 20 s breath-hold PET acquisition.

AIM: To determine whether a single 20 s breath-hold positron-emission tomography (PET) acquisition obtained during combined PET/computed tomography (CT)-guided percutaneous liver biopsy or ablation procedures has the potential to target 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG)-avid liver masses as accurately as up to 180 s breath-hold PET acquisitions. MATERIALS AND METHODS: This retrospective study included 10 adult patients with 13 liver masses who underwent FDG PET/CT-guided percutaneous biopsies (n = 5) or ablations (n = 5). PET was acquired as nine sequential 20 s, monitored, same-level breath-hold frames and CT was acquired in one monitored breath-hold. Twenty, 40, 60, and 180 s PET datasets were reconstructed. Two blinded readers marked tumour centres on randomized PET and CT datasets. Three-dimensional spatial localization differences between PET datasets and either 180 s PET or CT were analysed using multiple regression analyses. Statistical tests were two-sided and p < 0.05 was considered significant. RESULTS: Targeting differences between 20 s PET and 180 s PET ranged from 0.7-20.3 mm (mean 5.3 ± 4.4 mm; median 4.3) and were not statistically different from 40 or 60 s PET (p = 0.74 and 0.91, respectively). Targeting differences between 20 s PET and CT ranged from 1.4-36 mm (mean 9.6 ± 7.1 mm; median 8.2 mm) and were not statistically different from 40, 60, or 180 s PET (p = 0.84, 0.77, and 0.35, respectively). CONCLUSION: Single 20 s breath-hold PET acquisitions from PET/CT-guided percutaneous liver procedures have the potential to target FDG-avid liver masses with equivalent accuracy to 180 s summed, breath-hold PET acquisitions and may facilitate strategies that improve image registration and shorten procedure times.

Incidence, appropriateness, and consequences of recommendations for additional imaging tests in oncological PET/CT reports.

AIM: To assess the incidence, appropriateness, and outcomes of recommendations for additional imaging tests (RAI) in oncological combined 2-[(18)F]-fluoro-2-deoxy-d-glucose positron-emission tomography and computed tomography (FDG-PET/CT) reports. MATERIAL AND METHODS: In this retrospective study, conducted with institutional review board approval, the first oncological FDG-PET/CT reports in 2008 for 250 consecutive patients were reviewed to identify RAI. PET/CT reports containing RAI were retrospectively reviewed by two blinded readers. PET/CT findings prompting RAI, appropriateness of RAI, results of additional imaging tests actually performed, and the ultimate clinical significance of findings prompting RAI were recorded. Confirmation of clinical significance required pathology confirmation, unequivocal imaging progression, imaging stability for 12 months, or clinical follow-up for 24 months or end of life. RESULTS: Eighty-four RAI were identified for 88 PET/CT findings in 29.6% (74/250) of PET/CT reports, of which 51.2% (43/84) were deemed unnecessary by reviewers. Referring clinicians only followed 31% (26/84) of RAI by requesting additional imaging tests, and these tests resolved the PET/CT question in 76.9% (20/26) of those cases. Only 11.4% (10/88) of all findings prompting RAI proved to be clinically significant. Only 4.7% (2/43) of RAI deemed unnecessary by reviewers and 5.2% (3/58) of RAI not pursued by clinicians were found to be clinically significant; however, PET/CT alone was sufficient for diagnosis or guiding appropriate clinical management in each of these cases. CONCLUSION: RAI were found in 29.6% of oncological PET/CT reports. No potential adverse impact on patient management or outcome, by not issuing or following RAI, was identified in the 51.2% of RAI deemed unnecessary by study readers or in the 69% of RAI not pursued by referring clinicians.