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Updated: Dec 1, 2025
Thermal Ablation for the Treatment of Abdominal Tumors
Published on: March 7, 2011
Liver tumor F-18 FDG-PET before and immediately after microwave ablation enables imaging and quantification of tumor
Zihao Yan1,2, Ramin Khorasani1,2,3, Vincent M Levesque3
1Harvard Medical School, Boston, MA, USA.
Purpose:
Poor liver tumor visibility after microwave ablation (MWA) limits direct tumor ablation margin assessments using contrast-enhanced CT or ultrasound (US). Positron emission tomography (PET) or PET/CT may offer improved intraprocedural assessment of liver tumor ablation margins versus current imaging techniques, as 18F-fluorodeoxyglucose (18F-FDG)-avid tumors remain visible on PET immediately following ablation. The purpose of this study was to assess intraprocedural 18F-FDG PET scans before and immediately after PET/CT-guided MWA for visualization and quantification of metabolic liver tumor tissue contraction resulting from MWA.
Methods:
This retrospective study, conducted at a large academic medical center after Institutional Review Board approval, included 36 patients (20 men; mean age 63 [range 37-85]) who underwent PET/CT-guided MWA of 42 18F-FDG-avid liver tumors from May 2013 to March 2018. Tumor metabolic diameters (short/long axes) were measured for each tumor on pre- and post-ablation PET images. Tumor metabolic volumes were calculated using tumor diameter measurements and compared with automated volumes using an SUV threshold algorithm. A two-tailed paired t test was used for the analyses.
Results:
Comparing intraprocedural pre- and post-ablation PET images, mean metabolic tumor short- and long-axis diameters decreased from 21.4 to 14.9 mm [- 29%, p < 0.001, standard deviation (SD) 18%] and from 24.0 to 18.0 mm (- 24%, p < 0.001, SD 16%), respectively. The mean calculated tumor metabolic volume decreased from 10.5 to 4.6 mm3 (- 55%, p < 0.001, SD 26%). The mean automated tumor metabolic volume decreased from 10.6 to 5.8 mm3 (- 45%, p < 0.001, SD 30%).
Conclusion:
Intraprocedural PET images of 18F-FDG-avid liver tumors allow visualization and quantification of MWA-induced metabolic tumor tissue contraction during 18F-FDG PET/CT-guided procedures. The ability to visualize contracted tumor immediately post-MWA may facilitate emerging intraprocedural PET and PET/CT imaging techniques that address a clinical gap in directly assessing the ablation margin.
Insights
Positron emission tomography (PET) imaging can visualize liver tumor changes after microwave ablation (MWA). This study shows PET scans accurately quantify metabolic tumor volume reduction, improving ablation margin assessment.
Area of Science:
- Oncology
- Radiology
- Nuclear Medicine
Background:
- Liver tumor visibility after microwave ablation (MWA) is limited with conventional imaging like CT or ultrasound.
- Positron emission tomography (PET) offers potential for improved intraprocedural assessment of ablation margins due to the continued visibility of 18F-fluorodeoxyglucose (18F-FDG)-avid tumors post-ablation.
Purpose of the Study:
- To assess intraprocedural 18F-FDG PET scans before and immediately after PET/CT-guided MWA.
- To visualize and quantify metabolic liver tumor tissue contraction resulting from MWA.
Main Methods:
- Retrospective study of 36 patients with 42 18F-FDG-avid liver tumors undergoing PET/CT-guided MWA.
- Measurement of tumor metabolic diameters and calculation of metabolic volumes from pre- and post-ablation PET images.
- Comparison of manual and automated volume calculations using an SUV threshold algorithm.
Main Results:
- Mean metabolic tumor diameters decreased significantly post-ablation (short axis: -29%, long axis: -24%).
- Mean metabolic tumor volume showed substantial reduction (calculated: -55%, automated: -45%).
- All reductions were statistically significant (p < 0.001).
Conclusions:
- Intraprocedural PET imaging enables visualization and quantification of MWA-induced metabolic tumor contraction.
- This capability may support emerging PET and PET/CT techniques for direct assessment of liver tumor ablation margins.
