Impact of pretreatment PET/MRI on radiooncologic target delineation in Hodgkin’s lymphoma: a case series

TL;DR

This study compares PET/CT and PET/MRI for Hodgkin’s lymphoma staging and radiotherapy planning, finding both methods equally effective with PET/MRI offering less radiation exposure.

Contribution

The study evaluates PET/MRI as a radiation-reducing alternative to PET/CT for Hodgkin’s lymphoma target delineation.

Findings

PET/MRI and PET/CT showed no differences in disease staging.

Delineated tumor volumes had minor differences without clinical impact.

PET/MRI is a viable alternative with reduced radiation exposure.

Abstract

Positron-emission tomography combined with computed tomography (PET/CT) is the diagnostic standard for patients with Hodgkin’s lymphoma. Positron-emission tomography combined with magnetic resonance imaging (PET/MRI) is an alternative diagnostic modality that reduces radiation exposure to the patient. This study aims to evaluate the potential merits of PET/MRI compared to PET/CT for target delineation for radiotherapy of Hodgkin’s lymphoma.

Five patients with newly diagnosed Hodgkin’s lymphoma underwent PET/CT imaging directly followed by PET/MRI imaging as part of initial staging. Both modalities were subsequently compared regarding each patient’s diagnosed involved nodal regions. Three of these patients received radiotherapy after the completion of chemotherapy. In the radiotherapy planning CT, different gross tumor volumes and clinical target volumes were contoured for both PET/CT and PET/MRI and quantitatively compared using the Dice coefficient.

No differences regarding the diagnosed disease stage were observed. The delineated tumor and target volumes showed minor differences without clinical significance.

Positron-emission tomography/MRI is a viable option to assure adequate staging and later target delineation in patients with Hodgkin’s lymphoma. Due to the reduction of radiation exposure compared to PET/CT, it might be the preferable option if readily available.

Figures