Temporal analysis of intratumoral metabolic heterogeneity characterized by textural features in cervical cancer

Abstract

Purpose: The aim of this pilot study was to explore heterogeneity in the temporal behavior of intratumoral [(18)F]fluorodeoxyglucose (FDG) accumulation at a regional scale in patients with cervical cancer undergoing chemoradiotherapy.

Methods: Included in the study were 20 patients with FIGO stages IB1 to IVA cervical cancer treated with combined chemoradiotherapy. Patients underwent FDG PET/CT before treatment, during weeks 2 and 4 of treatment, and 12 weeks after completion of therapy. Patients were classified based on response to therapy as showing a complete metabolic response (CMR), a partial metabolic response (PMR), or residual disease and the development of new disease (NEW). Based on the presence of residual primary tumor following therapy, patients were divided into two groups, CMR and PMR/NEW. Temporal profiles of intratumoral FDG heterogeneity as characterized by textural features at a regional scale were assessed and compared with those of the standardized uptake value (SUV) indices (SUVmax and SUVmean) within the context of differentiating response groups.

Results: Textural features at a regional scale with emphasis on characterizing contiguous regions of high uptake in tumors decreased significantly with time (P < 0.001) in the CMR group, while features describing contiguous regions of low uptake along with those measuring the nonuniformity of contiguous isointense regions in tumors exhibited significant temporal changes in the PMR/NEW group (P < 0.03) but showed no persistent trends with time. Both SUV indices showed significant changes during the course of the disease in both patient groups (P < 0.001 for SUVmax and SUVmean in the CMR group; P = 0.0109 and 0.0136, respectively, for SUVmax and SUVmean in the PMR/NEW group), and also decreased at a constant rate in the CMR group and decreased up to the 4th week of treatment and then increased in the PMR/NEW group.

Conclusion: The temporal changes in the heterogeneity of intratumoral FDG distribution characterized at a regional scale using image-based textural features may provide an adjunctive or alternative option for understanding tumor response to chemoradiotherapy and interpreting FDG accumulation dynamics in patients with malignant cervical tumors during the course of the disease.

Figure 1

Temporal characteristics of HGRE (High Gray-level Runs Emphasis), SRHGE (Short Runs High Gray-level Emphasis), and LRHGE (Long Runs High Gray-level Emphasis) in patients of CMR. The first column represents respective line plots of HGRE, SRHGE, and LRHGE scores prior to treatment, at weeks 2 and 4, and after completion of treatment in patients with CMR; corresponding error bar plots for each feature are summarized in the second column with linear trends over the course of treatment fitted in red.

Figure 2

Temporal characteristics of HGZE (High Gray-level Zones Emphasis), SZHGE (Short Zones High Gray-level Emphasis), and LZHGE (Large Zones High Gray-level Emphasis) in patients of CMR. The first column represents respective line plots of HGZE, SZHGE, and LZHGE scores prior to treatment, at weeks 2 and 4, and after completion of treatment in patients of CMR; corresponding error bar plots for each feature are summarized in the second column with linear trends over the course of treatment fitted in red.

Figure 3

Temporal characteristics of SUV_max and SUV_mean in patients of CMR. The first column represents respective line plots of SUV_max and SUV_mean scores prior to treatment, at weeks 2 and 4, and after completion of treatment in patients with CMR; corresponding error bar plots for each SUV index are summarized in the second column with linear trends over the course of treatment fitted in red.

Figure 4

Temporal characteristics of SUV_max and SUV_min in patients of PMR/NEW. The first column represents respective line plots of SUV_max and SUV_min scores prior to treatment, at weeks 2 and 4, and after completion of treatment in patients with PMR/NEW; corresponding error bar plots for each SUV index are summarized in the second column with linear trends over the course of treatment fitted in red.

Figure 5

Box-plot representation of features’ values extracted at pre-treatment FDG-PET scans as a function of treatment outcome (CMR; PRM/NEW) for SUV_max (P = 0.1513) (1a), SUV_min (P = 0.2870) (1b), LGRE (Low Gray-level Runs Emphasis) (P = 0.0577) (2a), HGRE (High Gray-level Runs Emphasis) (P = 0.1513) (2b), LGZE (Low Gray-level Zones Emphasis) (P = 0.0577) (3a), and HGZE (High Gray-level Zones Emphasis) (P = 0.1511) (3b).