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

Abstract

Background To retrospectively assess liver tumor ablation margins using intraprocedural PET/CT images from FDG PET/CTguided 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.

MRI non-rigid registration with tumor contraction correction for ablative margin assessment after microwave ablation of hepatocellular carcinomas

“…In this study, we focused on the critical role of accurate registration in predicting residual tumor and analyzing AM, with a specific emphasis on addressing registration errors arising from tumor contraction (Tani et al 2016, Casadaban et al 2021. To tackle this issue, we introduced a tumor contraction model that utilizes the mean MEAV to calculate and adjust tumor volume following primary non-rigid registration.…”

Biopsy and Margins Optimize Outcomes after Thermal Ablation of Colorectal Liver Metastases

“…The 2D assessment is time-consuming, and most importantly, cannot reliably discriminate between tumors that will eventually progress versus those that will not [13]. Several methods have been described regarding the assessment of the ablation zone after TA of liver tumors [30][31][32][33][34][35][36][37][38][39][40][41]. Assessing minimal margin in all anatomical planes is desirable and can be accomplished by the use of 3D models [13,34,[36][37][38].…”

“…Assessing minimal margin in all anatomical planes is desirable and can be accomplished by the use of 3D models [13,34,[36][37][38]. It has been shown that multiplanar, stereotactic volumetric assessments can provide more reliable measurements than the 2D method [13,40,42,43], that is prone to error independently of the interventional radiologist's expertise in percutaneous tumor ablation [43]. However, both 2D and 3D methods rely on imaging.…”

Real-Time Split-Dose PET/CT-Guided Ablation Improves Colorectal Liver Metastasis Detection and Ablation Zone Margin Assessments without the Need for Repeated Contrast Injection

“…For biopsy-proven tumor-negative AZs, the MM size and SUV ratio were predictive surrogate imaging biomarkers of LTP [ 21 ]. Volumetric assessment of the MM has been used as an intraprocedural tool for ablation success [ 15 ] and a MM of 5 mm in a PET/CT ablation series correlated well with LTP [ 32 ]. In the current study, because of the imprecise portrayal of the tumor contour and edges, the theoretical 5- and 10-mm margins could not be defined in 32.1% of CLMs using CT alone.…”