Abstract
PurposeThe aim of the study was to evaluate the usefulness and accuracy of 18-fluorine-labeled fluorodeoxyglucose (PET) and magnetic resonance imaging (MRI) hybrid in gross tumor volume (GTV) delineation during radiotherapy planning in patients with carcinoma of the tongue.MethodsTen patients with squamous cell carcinoma (SCC) of the tongue underwent computed tomography (CT) and PET/MRI examination. The GTV for primary tumor and lymph nodes (nGTV) were defined on CT (GTV-CT) and compared to GTVs obtained from PET (GTV-PET) and MRI (GTV-MRI) images. Two methods of GTV determination were used: visual interpretation of CT, PET (GTV-PETvis) and MRI images and quantitative automatic method (Syngovia, Siemens) based on a chosen threshold value (20%, 30%, 40%, 50%) of standardized uptake values (SUVmax) from PET examination (GTV-PET20%, GTV-PET30%, etc.). Statistical analysis of differences in GTV values obtained from CT, PET and MRI studies was performed. GTV-CT was used as a reference.ResultsIn all, 80% of GTV-MRI and 40% of GTV-PETvis were larger than GTV-CT. Respectively, 20% of GTV-MRI and 60% of GTV-PETvis were smaller than GTV-CT. Taking into account all threshold measurements, 70% of volumes were smaller than GTV-CT. GTV-PET30% were the most closely related volumes to GTV-CT from all threshold methods in 50% of patients. GTV-PETvis generated the most similar volumes in relation to GTV-CT from all PET measurements. Statistical analysis confirmed those results. Compared to nGTV-CT, 70% of nGTV-MRI and 20% of nGTV-PETvis were larger. The remaining nGTV-MRI and nGTV-PETvis measurements were smaller than nGTV-CT. Measurements of all thresholds nGTVs were smaller than nGTV-CTV in 52.5% of cases. nGTV-PET20% were the most closely related volumes to nGTV-CT in 40% of the cases. Statistical analysis showed that nGTV-PET20% (p = 0.0468), nGTV-PETvis (p = 0.0166), and nGTV-PET50% (p = 0.0166) diverge significantly from nGTV-CT results. nGTV-MRI (p = 0.1141), nGTV-PET30% (p = 0.2845), and nGTV-PET40% (p = 0.5076) were significantly related with nGTV-CT.ConclusionCombination of PET/MRI provides more information during target tumor mass delineation in radiotherapy planning of patients with SCC of the tongue than other standard imaging methods. The most frequently matching threshold value was 30% of SUVmax for primary tumor delineation and 30–40% of SUVmax for nGTV determination.
Highlights
Head and neck cancers (HNC) are the sixth most common malignancy in the world [1]
Remaining nGTVMRI and node target volumes (nGTV)-PETvis measurements were smaller than nGTV-computed tomography (CT)
Statistical analysis (Fig. 2) showed that nGTV-PET20% (p = 0.0468) diverge significantly from nGTV-CT results, as well as nGTV-PETvis (p = 0.0166) and nGTV-PET50% (p = 0.0166). nGTV-magnetic resonance imaging (MRI) (p = 0.1141), nGTV-PET30% (p = 0.2845) and nGTV-PET40% (p = 0.5076) were the most significantly related with nGTV-CT
Summary
Head and neck cancers (HNC) are the sixth most common malignancy in the world [1]. Squamous cell carcinoma (SCC) is the major histology. Radiotherapy alone or with concurrent chemotherapy/immunotherapy, beside surgery, is the main treatment method of HNC patients [2]. Techniques characterized by high-precision dose delivery to the tumor, with maximal sparing of normal tissues, have been introduced to every-day practice including, among others, intensity modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT) and stereotactic radiotherapy/radiosurgery (SRT/SRS). Accurate definition of the target volumes is crucial in these techniques. Spatial error in volume delineation may result in early recurrence due to undertreatment near the tumor boundary or unnecessary damage to critical anatomical structures [2,3,4]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call