A review of the predictive role of functional imaging in patients with mucosal primary head and neck cancer treated with radiation therapy

Abstract

Advanced radiotherapy techniques, such as intensity-modulated radiotherapy, have been reported to reduce toxicities by improving the dose conformity in mucosal primary head and neck cancer (MPHNC). However, to further optimize the therapeutic ratio, details on individual patient and disease characteristics may be necessary to tailor treatments. This is likely to include identifying poor responders for treatment intensification and good responders for de-escalation strategies. Non-invasive, repeatable imaging biomarkers are attractive modalities in both pre-treatment and intra-treatment response prediction with a view to individualized treatment options. This review has assessed the current literature on the prognostic/predictive role of widely available functional imaging (FI) studies such as fMRI(functional magnetic resonance imaging), functional computed tomography (fCT) and positron-emission-tomography(PET). A literature search was carried out using Medline, Embase and PubMed. Studies were included if imaging was undertaken pre and/or during radiotherapy (with or without the addition of chemotherapy and/or surgery). A total of 99 relevant studies were identified: 14 fMRI, 10 fCT, 59 FDG-PET and 16 non-FDG-PET studies. These articles were reviewed to identify imaging parameters demonstrating a correlation with patient outcome or a factor considered to impact on patient outcome and thus likely to be of potential predictive value in MPHNC and associated future radiotherapy treatment directions. Several studies have demonstrated that both pre-treatment and mid-treatment FDG-PET is predictive of outcomes. However, further studies are required to confirm the role of other imaging studies including fMRI and PET using other tracers. There is large heterogeneity within and between published studies, including tumour sites, treatment options, outcome endpoints and parameters assessed. We propose a minimum set of factors that should be reported and make recommendations for studies evaluating the predictive utility in MPHNC.

Automated model‐based quantitative analysis of phantoms with spherical inserts in FDG PET scans

“…PET is commonly used in clinical trials as a more sensitive means of staging initial disease extent and to assess changes in tumor activity after treatment that may be detected sooner than changes in tumor volume, resulting in a faster and more accurate indication of treatment response. Many studies in the last two decades have assessed PET imaging as an enhanced indicator of response . However, differences among imaging protocols, image reconstructions, and inherent imaging properties of commercial PET/CT systems complicate reproducible quantitation.…”

“…Many studies in the last two decades have assessed PET imaging as an enhanced indicator of response. [1][2][3][4] However, differences among imaging protocols, image reconstructions, and inherent imaging properties of commercial PET/ CT systems complicate reproducible quantitation. This is particularly problematic in multi-institutional trials that may use a variety of PET/CT scanners with different imaging routines and reconstructions.…”

Task Group 174 Report: Utilization of [18F]Fluorodeoxyglucose Positron Emission Tomography ([18F]FDG‐PET) in Radiation Therapy

“…Response assessment is typically based on images acquired at one or more time points: pre‐therapy or post‐therapy; pre‐therapy vs post‐therapy; pre‐therapy vs intra‐therapy. The reader is recommended to extensive literature reviews on response assessment for head‐and‐neck cancer, esophageal cancer, lung cancer, and uterine/cervix cancer . These reviews cover response assessment based on image metrics extracted from segmented tumor volumes in the images, for example, maximum SUV, mean SUV, metabolic tumor volume (tumor volume above some SUV threshold), total lesion glycolysis (integral of SUV in the metabolic tumor volume), and, more recently, texture features.…”

PET-based prognostic survival model after radiotherapy for head and neck cancer

“…Finally, we exclusively investigated PET imaging. However, CT scan [58] and MRI image [59] analyses are also prognostic of patient outcome based on radiomic analysis including a large number of parameters.…”