研究目的
Investigating the relationship of standardized uptake values (SUVs) to radiobiological parameters, such as tumor control probability (TCP), to allow for quantitative prediction of tumor response based on SUVs from 18F-FDG PET before and after treatment for esophageal cancer.
研究成果
The TCP model was characterized using SUV in tumor before and after therapy. According to the TCP model, <SUVafter/SUVbefore> is a possible surrogate for cell survival in esophageal cancer patients. Despite the fact that CIs are large because of the small patient sample, parameters for a TCP curve can be derived and an individualized TCP can be calculated for future patients. Initial SUV did not predict for response, and a correlation was found between surrogates for tumor burden and cell kill.
研究不足
The patient number was small and a larger patient population may be needed to obtain TCP values with reasonably small CIs to clinically validate the model parameters.
1：Experimental Design and Method Selection:
The study analyzed data from 20 esophageal cancer patients treated with chemoradiotherapy (CRT) followed by surgery. Tumor pathologic response to CRT was assessed in surgical specimens. Patients underwent 18F-FDG PET imaging before and after CRT. Rigid image registration was performed between both images. TCP was modeled as a function of <SUVR>, a possible surrogate for average cell survival (<SUVR>=<SUVafter/SUVbefore>). TCP was represented by a sigmoid function with two parameters: SUVR50 and γ
2：The two parameters and their confidence intervals (CIs) were estimated using the maximum-likelihood method. Sample Selection and Data Sources:
The study was based on a cohort of 20 esophageal cancer patients treated with trimodality therapy (CRT followed by surgery) from 2006 to
3：All patients underwent both pre-CRT and post-CRT PET/CT imaging. List of Experimental Equipment and Materials:
20 PET images were attenuation corrected, with a resolution of 4.0×4.0×4.0 mm3, and CT images had a resolution of 0.98×0.98×4.0 mm3. Rigid image registration (VersorRigid3DTransform in the Insight Segmentation and Registration Toolkit 4.6.0; National Library of Medicine, Bethesda, MD) was used to register post-CRT CTs to pre-CRT CTs.
4：0×0×0 mm3, and CT images had a resolution of 98×98×0 mmRigid image registration (VersorRigid3DTransform in the Insight Segmentation and Registration Toolkit 0; National Library of Medicine, Bethesda, MD) was used to register post-CRT CTs to pre-CRT CTs. Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The tumor volume in the pre-CRT PET image was defined as the region with SUV >
5：Surgical resection was performed in all patients 1–7 weeks following the post-CRT PET/CT, and resected specimens were submitted to a pathologist for evaluation. Data Analysis Methods:
The maximum-likelihood estimate method was used to determine the parameters SUVR50 and γ50 that best fit the data. The correlation between SUV before CRT and SUV change <SUVbefore – SUVafter> was also studied.
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