18FDG PET Textural Indices in Adrenal Lesion

Tumors are characterized by a great heterogeneity. Characterizing this intra-tumor heterogeneity is a major challenge in oncology to improve the therapeutic management and move towards personalized medicine adapted to each patient. However, intra-tumor heterogeneity remains rarely used for diagnostic purposes The discovery of an adrenal mass can occur in different circumstances. Detection of an adrenal mass can be done in a context of secreting syndrome, in the assessment of an extra-adrenal neoplasia or fortuitously when performing an imaging for another reason. The etiologies are numerous (cortical tumors, medullary tumors, metastatic lesion of a extra-adrenal neoplasia, others). The adrenal masses can be divided into two categories, depending on whether they are hyperfunctional or not. In patients without an oncological history, an adrenal mass discovered is most often a benign adenoma, but requires an endocrine assessment. In patients with known primary cancer, approximately 30% of the adrenal masses are malignant.

In all cases, the diagnostic procedure includes an imaging assessment to characterize the lesion and an endocrine assessment. CT scan performed without and after intravenous iodinated contrast agent injection is the first-line examination to assess an adrenal mass.

18F-FDG-PET may be indicated as second-line for characterizing an adrenal mass. Adrenal tumor SUVmax (Standard Uptake Value) and adrenal tumor SUVmax / liver SUVmax ratio are routinely used to determine the malignancy of a lesion. Although very useful for assessing the glucose metabolism of a given lesion, these parameters do not allow assessing the heterogeneity of tumor uptake. The texture analysis corresponds to an analysis of the spatial distribution of FDG uptake, and allows, by the calculation of many indices, an evaluation of the heterogeneity of the tumors.

The hypothesis of our study is that the texture parameters could have an additional diagnostic value to improve the performance of conventional quantitative parameters to determine the malignancy of a lesion.

The objective of this study is to investigate the diagnostic value of texture indices in a large cohort of patients presenting an adrenal lesion