Assessing ablation margins of FDG-avid liver tumors during PET/CT-guided thermal ablation procedures: a retrospective study

• Published in: European journal of nuclear medicine and molecular imaging 2021-08, Vol.48 (9), p.2914-2924
• Main Authors: Casadaban, Leigh C., Catalano, Paul J., Lee, Leslie K., Hyun, Hyewon, Tuncali, Kemal, Gerbaudo, Victor H., Shyn, Paul B.
• Format: Article
• Language: English
• Subjects: Ablation; Cardiology; Computed tomography; Imaging; Liver; Liver cancer; Magnetic resonance imaging; Medical imaging; Medicine; Medicine & Public Health; Miscellanea; Nuclear Medicine; Oncology; Original Article; Orthopedics; Positron emission; Positron emission tomography; Radiology; Tomography; Tumors
• ISSN: 1619-7070; 1619-7089
• DOI: 10.1007/s00259-021-05206-5

Background To retrospectively assess liver tumor ablation margins using intraprocedural PET/CT images from FDG PET/CT-guided microwave or cryoablation procedures and to correlate minimum margin measurements with local progression outcomes. Methods Fifty-six patients (ages 36 to 85, median 62; 32 females) with 77 FDG-avid liver tumors underwent 60 FDG PET/CT guided, percutaneous microwave, or cryoablation procedures. Single breath-hold PET/CT images were used for intraprocedural assessment of the tumor ablation margin: liver tumors remained visible on PET immediately following ablation; microwave ablation zones were visible using contrast-enhanced CT; cryoablation zones (ice balls) were visible using unenhanced CT. Two readers retrospectively determined ablation margin assessability and measured the minimum ablation margin on intraprocedural PET/CT ( n = 77) and postprocedural MRI ( n = 56). Local tumor progression was assessed on all available follow-up imaging (1–49 months, mean 15). Local tumor progression was correlated with PET/CT minimum margin measurements using clustered survival models for 61 tumors. Results Minimum ablation margins were more often assessable using intraprocedural PET/CT (≥ 73/77 tumors, 95%) than postprocedural MRI (≤ 35/56 tumors, 63%). In 61 tumors with PET/CT-assessable margins (excluding tumors with overlapping ablations after PET/CT), there was a 6-fold increased risk of local tumor progression [hazard ratio (HR) 6.05; P = 0.004] for minimum ablation margins < 5 mm. Conclusion Breath-hold PET/CT scans, during PET/CT-guided microwave or cryoablation procedures for FDG-avid liver tumors, enable reliable intraprocedural assessment of the entire tumor ablation margin; a minimum PET/CT ablation margin threshold of 5 mm correlates well with local tumor progression outcomes.