Contemporary Imaging and Reporting Strategies for Head and Neck Cancer: MRI, FDG PET/MRI, NI-RADS, and Carcinoma of Unknown Primary-AJR Expert Panel Narrative Review

Merkel Cell Polyomavirus (MCPyV) and Its Possible Role in Head and Neck Cancers

Despite significant progress in its prevention, diagnosis, and treatment, head and neck cancer (HNC) remains a major global health issue due to its multifactorial pathogenesis. Indeed, HNCs have been found to be associated with different environmental and lifestyle factors, as well as with infection with oncogenic viruses. To date, seven viruses are recognized for their tumorigenic properties and have been proposed as implicated in HNC development, including Merkel Cell Polyomavirus (MCPyV). MCPyV is well recognized as the major etiological agent of Merkel cell carcinoma (MCC), a rare but rapidly metastasizing skin neoplasm. Specifically, in almost 80% of MCC cases, viral genome integration occurs, and a truncated form of Large T Antigen (tLT) is expressed. Although MCC is a rare cancer, MCPyV is a ubiquitous virus, widely distributed among the human population. Therefore, a plausible role of the virus has been proposed, even for other tumors. The current review provides an overview of the available data describing the presence of MCPyV in non-MCC tumors, such as HNCs, with the aim of elucidating the potential contribution of MCPyV to oral cancer. Understanding the role of viral infections in the etiology of cancer opens up the opportunity for developing preventive measures and targeted therapies that effectively address HNC progression while reducing treatment-related side effects.

Circulating tumor DNA in human papillomavirus-associated oropharyngeal cancer management: A systematic review

OBJECTIVE

Circulating tumor DNA (ctDNA) has emerged as a promising tool in the treatment of HPV-associated oropharyngeal squamous cell cancer (OPSCC). This systematic review sought to answer the question: what is the current role of ctDNA in the diagnosis, treatment, and surveillance of HPV-associated OPSCC?

DATA SOURCES

Medline (Ovid), Embase (Ovid), Scopus.

REVIEW METHODS

Original articles studying the role of ctDNA in the diagnosis or surveillance of HPV-associated OPSCC were eligible for inclusion. Two authors independently reviewed studies for inclusion and abstracted data, including study design, characterization of liquid biopsy technology, and diagnostic outcomes.

RESULTS

After a preliminary screening of 441 studies, 23 were selected for inclusion. Ten studies were conducted retrospectively, and 13 were conducted prospectively. In these studies, diagnostic testing included plasma-based droplet digital polymerase chain reaction (ddPCR, n = 13), quantitative PCR (qPCR, n = 4), digital PCR (dPCR, n = 3), next-generation sequencing (NGS) (n = 3), or a ctDNA detection kit (n = 1). Diagnostic outcomes were reported for pre-diagnosis (n = 1), pre-treatment (n = 17), during treatment (n = 6), and surveillance/recurrence (n = 11) timepoints. Test sensitivities ranged from 20.6 %-100 % pre-treatment and 72 %-100 % during surveillance, while test specificities ranged from 95 %-100 % pre-treatment and 87.2 %-100 % during surveillance.

CONCLUSION

The majority of studied ctDNA technologies allow for detection of HPV-associated OPSCC with high diagnostic accuracy. However, heterogeneity is introduced by test type and assay used. These findings highlight the utility, as well as limitations, of ctDNA in the diagnosis, treatment monitoring, and surveillance of HPV-associated OPSCC. Future studies and clinical consensus will need to address acceptable diagnostic accuracy thresholds for clinical use.

Application of Surface-Enhanced Raman Spectroscopy in Head and Neck Cancer Diagnosis

Surface-enhanced Raman spectroscopy (SERS) has emerged as a crucial analytical tool in the field of oncology, particularly presenting significant challenges for the diagnosis and treatment of head and neck cancer. This Review provides an overview of the current status and prospects of SERS applications, highlighting their profound impact on molecular biology-level diagnosis, tissue-level identification, HNC therapeutic monitoring, and integration with emerging technologies. The application of SERS for single-molecule assays such as epidermal growth factor receptors and PD-1/PD-L1, gene expression analysis, and tumor microenvironment characterization is also explored. This Review showcases the innovative applications of SERS in liquid biopsies such as high-throughput lateral flow analysis for ctDNA quantification and salivary diagnostics, which can offer rapid and highly sensitive assays suitable for immediate detection. At the tissue level, SERS enables cancer cell visualization and intraoperative tumor margin identification, enhancing surgical precision and decision-making. The role of SERS in radiotherapy, chemotherapy, and targeted therapy is examined along with its use in real-time pharmacokinetic studies to monitor treatment response. Furthermore, this Review delves into the synergistic relationship between SERS and artificial intelligence, encompassing machine learning and deep learning algorithms, marking the dawn of a new era in precision oncology. The integration of SERS with genomics, metabolomics, transcriptomics, proteomics, and single-cell omics at the multiomics level will revolutionize our comprehension and management of HNC. This Review offers an overview of the transformative impacts of SERS and examines future directions as well as challenges in this dynamic research field.

Development and validation of MRI-derived deep learning score for non-invasive prediction of PD-L1 expression and prognostic stratification in head and neck squamous cell carcinoma

BACKGROUND

Immunotherapy has revolutionized the treatment landscape for head and neck squamous cell carcinoma (HNSCC) and PD-L1 combined positivity score (CPS) scoring is recommended as a biomarker for immunotherapy. Therefore, this study aimed to develop an MRI-based deep learning score (DLS) to non-invasively assess PD-L1 expression status in HNSCC patients and evaluate its potential effeciency in predicting prognostic stratification following treatment with immune checkpoint inhibitors (ICI).

METHODS

In this study, we collected data from four patient cohorts comprising a total of 610 HNSCC patients from two separate institutions. We developed deep learning models based on the ResNet-101 convolutional neural network to analyze three MRI sequences (T1WI, T2WI, and contrast-enhanced T1WI). Tumor regions were manually segmented, and features extracted from different MRI sequences were fused using a transformer-based model incorporating attention mechanisms. The model's performance in predicting PD-L1 expression was evaluated using the area under the curve (AUC), sensitivity, specificity, and calibration metrics. Survival analyses were conducted using Kaplan-Meier survival curves and log-rank tests to evaluate the prognostic significance of the DLS.

RESULTS

The DLS demonstrated high predictive accuracy for PD-L1 expression, achieving an AUC of 0.981, 0.860 and 0.803 in the training, internal and external validation cohort. Patients with higher DLS scores demonstrated significantly improved progression-free survival (PFS) in both the internal validation cohort (hazard ratio: 0.491; 95% CI, 0.270-0.892; P = 0.005) and the external validation cohort (hazard ratio: 0.617; 95% CI, 0.391-0.973; P = 0.040). In the ICI-treated cohort, the DLS achieved an AUC of 0.739 for predicting durable clinical benefit (DCB).

CONCLUSIONS

The proposed DLS offered a non-invasive and accurate approach for assessing PD-L1 expression in patients with HNSCC and effectively stratified HNSCC patients to benefit from immunotherapy based on PFS.

An international survey of diffusion and perfusion magnetic resonance imaging implementation in the head and neck

OBJECTIVE

The goal of this international survey was to understand how diffusion (DWI) and perfusion imaging (PWI) are being applied to clinical head and neck imaging.

METHODS AND MATERIALS

An online questionnaire focusing on acquisition, clinical indications, analysis, and reporting of qualitative DWI (QlDWI), quantitative DWI (QnDWI) and dynamic contrast-enhanced PWI (DCE-PWI) in the head and neck was circulated to members of the American Society of Head and Neck Radiology (ASHNR) and European Society of Head and Neck Radiology (ESHNR) over a 3-month period. Descriptive statistics and group comparisons were calculated with SPSS® v27.

RESULTS

There were 294 unique respondents (17.6% response rate) from 256 institutions (182 ESHNR, 74 ASHNR). DWI was routinely acquired for some head and neck indications at 95.7% of the respondents' institutions, with 92.5% of radiologists interpreting QlDWI but only 36.7% analysing QnDWI. QlDWI was most frequently applied to primary mucosal masses or the middle ear, whilst QnDWI was routinely used to distinguish tumour histologies, and primary or recurrent carcinoma. DCE-PWI was routinely acquired at 53.6% of institutions and used by 40.8% of respondents, however, there was no clinical scenario in which it was routinely applied by most users. DCE-PWI analysis methods varied, with time-intensity curve classifications being the most frequently reported. Lack of standardisation was identified as a key reason for not implementing QnDWI, whilst numerous factors prevented the adoption of DCE-PWI.

CONCLUSION

There is widespread routine interpretation of QlDWI by head and neck radiologists, but there is considerable variation in the application and analysis of head and neck QnDWI and DCE-PWI.

KEY POINTS

Question How are diffusion (DWI) and dynamic contrast-enhanced perfusion imaging (DCE-PWI) being utilised by head and neck radiologists across a wide range of practices? Findings An international survey demonstrated widespread routine interpretation of qualitative DWI but variable application and analysis of quantitative DWI and DCE-PWI with numerous barriers to implementation. Clinical relevance The survey results will aid discussion on how to standardise and optimally disseminate these MRI techniques in day-to-day practice. More focused education and resource allocation may be required to accelerate the adoption of quantitative DWI and DCE-PWI.

Radiographic Response Assessments and Standardized Imaging Interpretation Criteria in Head and Neck Cancer on FDG PET/CT: A Narrative Review

INTRODUCTION

There is growing interest in the development and application of standardized imaging criteria (SIC), to minimize variability and improve the reproducibility of image interpretation in head and neck squamous cell carcinoma (HNSCC).

METHODS

"Squamous cell carcinoma" AND "standardized interpretation criteria" OR "radiographic response assessment" were searched using PubMed and Google Scholar for articles published between 2009 and 2024, returning 56 publications. After abstract review, 18 were selected for further evaluation, and 6 different SICs (i.e., PERCIST, Porceddu, Hopkins, NI-RADS, modified Deauville, and Cuneo) were included in this review. Each SIC is evaluated in the context of 8 desired traits of a standardized reporting system.

RESULTS

Two SICs have societal endorsements (i.e., PERCIST, NI-RADS); four can be used in the evaluation of locoregional and systemic disease (i.e., PERCIST, Hopkins, NI-RADS, Cuneo), and four have specific categories for equivocal imaging results (i.e., Porceddu, NI-RADS, modified Deauville, and Cuneo). All demonstrated areas for future improvement in the context of the 8 desired traits.

CONCLUSION

Multiple SICs have been developed for and demonstrated value in HNSCC post-treatment imaging; however, these systems remain underutilized. Selecting an SIC with features that best match the needs of one's practice is expected to maximize the likelihood of successful implementation.

Utility of TTMV-HPV DNA in resolving indeterminate findings during oropharyngeal cancer surveillance

OBJECTIVES

Clinical and imaging examinations frequently have indeterminate results during cancer surveillance, which can lead to overtreatment and cause psychological and financial harm to the patient. This study addresses the critical need to enhance diagnostic precision and decision-making in the management of HPV-associated oropharyngeal cancer. This study evaluated the utility of tumor tissue-modified viral (TTMV)-HPV DNA to resolve indeterminate disease status following definitive treatment for HPV-associated oropharyngeal cancer.

MATERIALS AND METHODS

In this retrospective cohort, patients treated for HPV-associated oropharyngeal cancer at eight U.S. institutions and who received one or more TTMV-HPV DNA tests during post-treatment surveillance between February 2020 and January 2022 were included.

RESULTS

Among 543 patients, 210 patients (38.7%; 210/543) experienced one or more clinically indeterminate findings (CIFs) during surveillance, with 503 CIFs recorded. Of those patients with an "indeterminate" disease status at a point during surveillance, 79 were associated with contemporaneous TTMV-HPV DNA testing. TTMV-HPV DNA testing demonstrated high accuracy (97.5%; 77/79) in correctly determining recurrence status. Patients whose disease status was "indeterminate" at the time of a positive TTMV-HPV DNA test were clinically confirmed to recur faster than those whose disease status was "no evidence of disease." Only 3% of patients (17/543) experienced indeterminate TTMV-HPV DNA tests during surveillance. Discordance between TTMV-HPV DNA tests and clinical results was minimal, with only 0.6% (3/543) of patients showing positive tests without recurrence.

CONCLUSION

Our findings support the utility of circulating TTMV-HPV DNA in resolving indeterminate disease status and informing the subsequent clinical course.

The Role of Oncogenic Viruses in Head and Neck Cancers: Epidemiology, Pathogenesis, and Advancements in Detection Methods

Head and neck cancers (HNCs) constitute a wide range of malignancies originating from the epithelial lining of the upper aerodigestive tract, including the oral cavity, pharynx, larynx, nasal cavity, paranasal sinuses, and salivary glands. Although lymphomas affecting this region are not conventionally classified as HNCs, they may occur in lymph nodes or mucosa-associated lymphoid tissues within the head and neck. Oncogenic viruses play a crucial role in HNC onset. Human papillomavirus (HPV) is extensively studied for its association with oropharyngeal cancers; nevertheless, other oncogenic viruses also contribute to HNC development. This review provides an overview of the epidemiology, pathogenesis, and advancements in detection methods of oncogenic viruses associated with HNCs, recognizing HPV's well-established role while exploring additional viral connections. Notably, Epstein-Barr virus is linked to nasopharyngeal carcinoma and lymphomas. Human herpesvirus 8 is implicated in Kaposi's sarcoma, and Merkel cell polyomavirus is associated with subsets of HNCs. Additionally, hepatitis viruses are examined for their potential association with HNCs. Understanding the viral contributions in the head and neck area is critical for refining therapeutic approaches. This review underlines the interaction between viruses and malignancies in this region, highlighting the necessity for ongoing research to elucidate additional mechanisms and enhance clinical outcomes.

Predicting Response to Exclusive Combined Radio-Chemotherapy in Naso-Oropharyngeal Cancer: The Role of Texture Analysis

The aim of this work is to identify MRI texture features able to predict the response to radio-chemotherapy (RT-CHT) in patients with naso-oropharyngeal carcinoma (NPC-OPC) before treatment in order to help clinical decision making. Textural features were derived from ADC maps and post-gadolinium T1-images on a single MRI machine for 37 patients with NPC-OPC. Patients were divided into two groups (responders/non-responders) according to results from MRI scans and 18F-FDG-PET/CT performed at follow-up 3-4 and 12 months after therapy and biopsy. Pre-RT-CHT lesions were segmented, and radiomic features were extracted. A non-parametric Mann-Whitney test was performed. A p-value < 0.05 was considered significant. Receiver operating characteristic curves and area-under-the-curve values were generated; a 95% confidence interval (CI) was reported. A radiomic model was constructed using the LASSO algorithm. After feature selection on MRI T1 post-contrast sequences, six features were statistically significant: gldm_DependenceEntropy and DependenceNonUniformity, glrlm_RunEntropy and RunLengthNonUniformity, and glszm_SizeZoneNonUniformity and ZoneEntropy, with significant cut-off values between responder and non-responder group. With the LASSO algorithm, the radiomic model showed an AUC of 0.89 and 95% CI: 0.78-0.99. In ADC, five features were selected with an AUC of 0.84 and 95% CI: 0.68-1. Texture analysis on post-gadolinium T1-images and ADC maps could potentially predict response to therapy in patients with NPC-OPC who will undergo exclusive treatment with RT-CHT, being, therefore, a useful tool in therapeutical-clinical decision making.

Role of 18F-FDG PET/CT in Head and Neck Squamous Cell Carcinoma: Current Evidence and Innovative Applications

This article provides an overview of the use of 18F-FDG PET/CT in various clinical scenarios of head-neck squamous cell carcinoma, ranging from initial staging to treatment-response assessment, and post-therapy follow-up, with a focus on the current evidence, debated issues, and innovative applications. Methodological aspects and the most frequent pitfalls in head-neck imaging interpretation are described. In the initial work-up, 18F-FDG PET/CT is recommended in patients with metastatic cervical lymphadenectomy and occult primary tumor; moreover, it is a well-established imaging tool for detecting cervical nodal involvement, distant metastases, and synchronous primary tumors. Various 18F-FDG pre-treatment parameters show prognostic value in terms of disease progression and overall survival. In this scenario, an emerging role is played by radiomics and machine learning. For radiation-treatment planning, 18F-FDG PET/CT provides an accurate delineation of target volumes and treatment adaptation. Due to its high negative predictive value, 18F-FDG PET/CT, performed at least 12 weeks after the completion of chemoradiotherapy, can prevent unnecessary neck dissections. In addition to radiomics and machine learning, emerging applications include PET/MRI, which combines the high soft-tissue contrast of MRI with the metabolic information of PET, and the use of PET radiopharmaceuticals other than 18F-FDG, which can answer specific clinical needs.

Posttreatment Head and Neck Cancer Imaging: Anatomic Considerations Based on Cancer Subsites

Posttreatment imaging surveillance of head and neck cancer is challenging owing to complex anatomic subsites and diverse treatment modalities. Early detection of residual disease or recurrence through surveillance imaging is crucial for devising optimal treatment strategies. Posttreatment imaging surveillance is performed using CT, fluorine 18-fluorodeoxyglucose PET/CT, and MRI. Radiologists should be familiar with postoperative imaging findings that can vary depending on surgical procedures and reconstruction methods that are used, which is dictated by the primary subsite and extent of the tumor. Morphologic changes in normal structures or denervation of muscles within the musculocutaneous flap may mimic recurrent tumors. Recurrence is more likely to occur at the resection margin, margin of the reconstructed flap, and deep sites that are difficult to access surgically. Radiation therapy also has a varying dose distribution depending on the primary site, resulting in various posttreatment changes. Normal tissues are affected by radiation, with edema and inflammation occurring in the early stages and fibrosis in the late stages. Distinguishing scar tissue from residual tumor becomes necessary, as radiation therapy may leave behind residual scar tissue. Local recurrence should be carefully evaluated within areas where these postradiation changes occur. Head and Neck Imaging Reporting and Data System (NI-RADS) is a standardized reporting and risk classification system with guidance for subsequent management. Familiarity with NI-RADS has implications for establishing surveillance protocols, interpreting posttreatment images, and management decisions. Knowledge of posttreatment imaging characteristics of each subsite of head and neck cancers and the areas prone to recurrence empowers radiologists to detect recurrences at early stages. ©RSNA, 2024 Test Your Knowledge questions in the supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

PET/MR Imaging in Head and Neck Cancer

Head and neck squamous cell carcinoma (HNSCC) can either be examined with hybrid PET/MR imaging systems or sequentially, using PET/CT and MR imaging. Regardless of the acquisition technique, the superiority of MR imaging compared to CT lies in its potential to interrogate tumor and surrounding tissues with different sequences, including perfusion and diffusion. For this reason, PET/MR imaging is preferable for the detection and assessment of locoregional residual/recurrent HNSCC after therapy. In addition, MR imaging interpretation is facilitated when combined with PET. Nevertheless, distant metastases and distant second primary tumors are detected equally well with PET/MR imaging and PET/CT.

Personalizing Surveillance in Head and Neck Cancer

Head and neck squamous cell carcinoma (HNSCC) encompasses a spectrum of heterogeneous diseases originating in the oral cavity, pharynx, and larynx. Within the United States, head and neck cancer (HNC) accounts for 66,470 new cases, or 3% of all malignancies, annually.¹ The incidence of HNC is rising, largely driven by increases in oropharyngeal cancer.^2-4 Recent molecular and clinical advancements, particularly with regard to molecular and tumor biology, reflect the heterogeneity of the subsites contained within the head and neck. Despite this, existing guidelines for post-treatment surveillance remain broad without much consideration given to different anatomic subsites and etiologic factors (such as human papillomavirus [HPV] status or tobacco exposure).⁵ Surveillance incorporating the physical examination, imaging, and emerging molecular biomarkers is an essential part of care for patients treated for HNC and allows for the detection of locoregional recurrence, distant metastases, and second primary malignancies aiming for better functional and survival outcomes. Additionally, it allows for evaluation and management of post-treatment complications.