Dissemination patterns of Hodgkin lymphoma using a probability network model based on [¹⁸F]-FDG PET/CT

The preferred hypothesis for the dissemination patterns of Hodgkin lymphoma (HL) is the contiguity hypothesis. However, this hypothesis is based on studies performed before the advent of [¹⁸F]-FDG PET/CT which is now the established reference for HL staging. This study aims to extract the dissemination patterns of HL using [¹⁸F]-FDG PET/CT and a probability network model.

We retrospectively analyzed [¹⁸F]-FDG PET/CT performed for initial staging of patients with classical HL. The HL involvement status (presence of absence) was reported for 19 supra- and infra-diaphragmatic lymph node regions and 4 extranodal regions (lung, spleen, liver, and osteo- medullary). The analysis of HL dissemination was carried out using HL involvement status for all regions through 3 distinct methods: comparison of nearby lymph node regions, correlation assessment between all regions and relationship strength between all regions using Ising network model.

A total of 196 patients were included. Our results showed strong relationships between nearby involved lymph node regions (for example between the left pelvic and the abdominal lymph node regions (relationship strength = 0.980)) and between more distant regions (for example between right and left axillary lymph node regions (strength = 0.714)). Furthermore, involvement of the infra-diaphragmatic lymph node regions was significantly correlated with Ann Arbor stage IV (phi = 0.56, p < 0.001).

This study confirms the hypothesis of lymphatic dissemination of HL in a contiguous mode, with additional links between more distant regions. These predictable dissemination patterns could be useful for the initial staging assessment of patients with HL using [¹⁸F]-FDG PET/CT.