Tumor volume definitions in head and neck squamous cell carcinoma - Comparing PET/MRI and histopathology

Emmanouil Terzidis; Jeppe Friborg; Ivan R Vogelius; Giedrius Lelkaitis; Christian von Buchwald; Anders B Olin; Helle H Johannesen; Barbara M Fischer; Irene Wessel; Jacob H Rasmussen

doi:10.1016/j.radonc.2023.109484

Tumor volume definitions in head and neck squamous cell carcinoma - Comparing PET/MRI and histopathology

Radiother Oncol. 2023 Mar:180:109484. doi: 10.1016/j.radonc.2023.109484. Epub 2023 Jan 20.

Affiliations

¹ Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen, Denmark; Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden.
² Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen, Denmark.
³ Department of Pathology, Rigshospitalet, Copenhagen, Denmark.
⁴ Department of Otorhinolaryngology, Head & Neck Surgery and Audiology, Rigshospitalet, Copenhagen, Denmark.
⁵ Department of Clinical Physiology and Nuclear Medicine, Rigshospitalet, University of Copenhagen, Denmark.
⁶ Department of Clinical Physiology and Nuclear Medicine, Rigshospitalet, University of Copenhagen, Denmark; Department of Clinical Medicine, University of Copenhagen, Denmark.
⁷ Department of Otorhinolaryngology, Head & Neck Surgery and Audiology, Rigshospitalet, Copenhagen, Denmark; Department of Clinical Medicine, University of Copenhagen, Denmark. Electronic address: jacob.hoeygaard.rasmussen.01@regionh.dk.

PMID: 36690303
DOI: 10.1016/j.radonc.2023.109484

Abstract

Background and purpose: In cancer treatment precise definition of the tumor volume is essential, but despite development in imaging modalities, this remains a challenge. Here, pathological tumor volumes from the surgical specimens were obtained and compared to tumor volumes defined from modern PET/MRI hybrid imaging. The purpose is to evaluate mismatch between the volumes defined from imaging and pathology was estimated and potential clinical impact.

Methods and materials: Twenty-five patients with head and neck squamous cell carcinoma were scanned on an integrated PET/MRI system prior to surgery. Three gross tumor volumes (GTVs) from the primary tumor site were delineated defined from MRI (GTV_MRI), PET (GTV_PET) and one by utilizing both anatomical images and clinical information (GTV_ONCO). Twenty-five primary tumor specimens were extracted en bloc, scanned with PET/MRI and co-registered to the patient images. Each specimen was sectioned in blocks, sliced and stained with haematoxylin and eosin. All slices were digitalized and tumor delineated by a head and neck pathologist. The pathological tumor areas in all slices were interpolated yielding a pathological 3D tumor volume (GTV_PATO). GTV_PATOwas compared with the imaging GTV's and potential mismatch was estimated.

Results: Thirteen patients were included. The mean volume of GTV_ONCOwas larger than the GTV's defined from PET or MRI. The mean mismatch of the GTV_PATOcompared to the GTV_PET, GTV_MRIand GTV_ONCOwas 31.9 %, 54.5 % and 27.9 % respectively, and the entire GTV_PATO was only fully encompassed in GTV_ONCO in 1 of 13 patients. However, after the addition of a clinical 5 mm margin the GTV_PATO was fully encompassed in GTV_ONCO in 11 out of 13 patients.

Conclusions: Despite modern hybrid imaging modalities, a mismatch between imaging and pathological defined tumor volumes was observed in all patients.A 5 mm clinical margin was sufficient to ensure inclusion of the entire pathological volume in 11 out of 13 patients.

Keywords: Magnetic resonance imaging; Pathology; Positron emission tomography; Squamous cell carcinoma of head and neck.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Fluorodeoxyglucose F18
Head and Neck Neoplasms* / diagnostic imaging
Humans
Magnetic Resonance Imaging / methods
Positron-Emission Tomography / methods
Radiopharmaceuticals
Squamous Cell Carcinoma of Head and Neck / diagnostic imaging
Tomography, X-Ray Computed* / methods
Tumor Burden

Substances

Fluorodeoxyglucose F18
Radiopharmaceuticals