Clinical Practice in PET/CT for the Management of Head and Neck Squamous Cell Cancer

The Evolving Role of Novel Imaging Techniques for Radiotherapy Planning

The ability to visualise cancer with imaging has been crucial to the evolution of modern radiotherapy (RT) planning and delivery. And as evolving RT technologies deliver increasingly precise treatment, the importance of accurate identification and delineation of disease assumes ever greater significance. However, innovation in imaging technology has matched that seen with RT delivery platforms, and novel imaging techniques are a focus of much research activity. How these imaging modalities may alter and improve the diagnosis and staging of cancer is an important question, but already well served by the literature. What is less clear is how novel imaging techniques may influence and improve practical and technical aspects of RT planning and delivery. In this review, current gold standard approaches to integration of imaging, and potential future applications of bleeding-edge imaging technology into RT planning pathways are explored.

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.

Quarter Century Positron Emission Tomography/Computed Tomography Transformation of Oncology: Head and Neck Cancer

During the last 2 decades, f-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F FDG PET/CT) has transformed the clinical head and neck cancer imaging for patient management and predicting survival outcomes. It is now widely used for staging, radiotherapy planning, posttherapy assessment, and for detecting recurrence in head and neck cancers and is widely included in NCCN and other evidence based clinical practice guidelines. Future Directions would include evaluating the potential value of FAPI PET/CT for head and neck cancers, opportunity to use volumetric and tumor heterogeneity parameters and deploying AI in diagnostic and therapeutic assessments.

The clinical acceptability of short versus long duration acquisitions for head and neck cancer using long-axial field-of-view PET/CT: a retrospective evaluation

PURPOSE

To evaluate the utility of long duration (10 min) acquisitions compared to standard 4 min scans in the evaluation of head and neck cancer (HNC) using a long-axial field-of-view (LAFOV) system in 2-[18F]FDG PET/CT.

METHODS

HNC patients undergoing LAFOV PET/CT were included retrospectively according to a predefined sample size calculation. For each acquisition, FDG avid lymph nodes (LN) which were highly probable or equivocal for malignancy were identified by two board certified nuclear medicine physicians in consensus. The aim of this study was to establish the clinical acceptability of short-duration (4 min, C40%) acquisitions compared to full-count (10 min, C100%) in terms of the detection of LN metastases in HNC. Secondary endpoints were the positive predictive value for LN status (PPV) and comparison of SUVmax at C40% and C100%. Histology reports or confirmatory imaging were the reference standard.

RESULTS

A total of 1218 records were screened and target recruitment was met with n = 64 HNC patients undergoing LAFOV. Median age was 65 years (IQR: 59-73). At C40%, a total of 387 lesions were detected (highly probable LN n = 274 and equivocal n = 113. The total number of lesions detected at C100% acquisition was 439, of them 291 (66%) highly probable LN and 148 (34%) equivocal. Detection rate between the two acquisitions did not demonstrate any significant differences (Pearson's Chi-Square test, p = 0.792). Sensitivity, specificity, PPV, NPV and accuracy for C40% were 83%, 44%, 55%, 76% and 36%, whilst for C100% were 85%, 56%, 55%, 85% and 43%, respectively. The improved accuracy reached borderline significance (p = 0.057). At the ROC analysis, lower SUVmax was identified for C100% (3.5) compared to C40% (4.5).

CONCLUSION

In terms of LN detection, C40% acquisitions showed no significant difference compared to the C100% acquisitions. There was some improvement for lesions detection at C100%, with a small increment in accuracy reaching borderline significance, suggestive that the higher sensitivity afforded by LAFOV might translate to improved clinical performance in some patients.

Imaging of Tumor Stroma Using 68Ga-FAPI PET/CT to Improve Diagnostic Accuracy of Primary Tumors in Head and Neck Cancer of Unknown Primary: A Comparative Imaging Trial

The low detection rate of primary tumors by current diagnostic techniques remains a major concern for patients with head and neck cancer of unknown primary (HNCUP). Therefore, in this study, we aimed to investigate the potential role of 68Ga-labeled fibroblast activation protein inhibitor (68Ga-FAPI) PET/CT compared with 18F-FDG PET/CT for the detection of primary tumors of HNCUP. Methods: In this prospective comparative imaging trial conducted at Fudan University Shanghai Cancer Center, 91 patients with negative or equivocal findings of a primary tumor by comprehensive clinical examination and conventional imaging were enrolled from June 2020 to September 2022. The presence of a primary tumor was recorded by 3 experienced nuclear medicine physicians. Primary lesions were validated by histopathologic analysis and a composite reference standard. Results: Of the 91 patients (18 women, 73 men; median age, 60 y; age range, 24-76 y), primary tumors were detected in 46 (51%) patients after a thorough diagnostic work-up. 68Ga-FAPI PET/CT detected more primary lesions than 18F-FDG PET/CT (46 vs. 17, P < 0.001) and showed better sensitivity, positive predictive value, and accuracy in locating primary tumors (51% vs. 25%, 98% vs. 43%, and 51% vs. 19%, respectively). Furthermore, 68Ga-FAPI PET/CT led to treatment changes in 22 of 91 (24%) patients compared with 18F-FDG PET/CT. The Kaplan-Meier curve illustrated that patients with unidentified primary tumors had a significantly worse prognosis than patients with identified primary tumors (hazard ratio, 5.77; 95% CI, 1.86-17.94; P = 0.0097). Conclusion: 68Ga-FAPI PET/CT outperforms 18F-FDG PET/CT in detecting primary lesions and could serve as a sensitive, reliable, and reproducible imaging modality for HNCUP patients.

Predictability and Utility of Contrast-Enhanced CT on Occult Lymph Node Metastasis for Patients with Clinical Stage IA-IIA Lung Adenocarcinoma: A Double-Center Study

RATIONALE AND OBJECTIVES

With the advantage of minimizing damage and preserving more functional lung tissue, limited surgery is considered depend on the lymph node (LN) involvement situation. However, occult lymph node metastasis (OLM) may be ignored by limited surgery and become a risk factor for local recurrence after surgical resection. The aim of this study was to assess the risk factors for OLM based on computed tomography enhanced image in patients with clinical lung adenocarcinoma (ADC).

MATERIALS AND METHODS

From January 2016 to July 2022, 707 patients with clinical stage IA-IIA ADC underwent lobectomy with systematic LN dissection and were divided into training and validation group based on different institution. Univariate analysis followed by multivariable logistic regression were performed to estimate different risk factors of OLM. A predictive model was established with visual nomogram and external validation, and evaluated in terms of accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve (AUC).

RESULTS

Fifty-nine patients were diagnosed with OLM (11.9%), and four independent predictors of LN involvement were identified: larger consolidation diameter (odds ratio [OR], 2.35, 95% confidence interval [CI]: 1.06, 5.22, p = 0.013), bronchovascular bundle thickening (OR, 1.99, 95% CI: 1.00, 3.95, p = 0.049), lobulation (OR, 2.92, 95% CI: 1.22, 6.99, p = 0.016) and obstructive change (OR, 1.69, 95% CI: 1.17, 6.16, p = 0.020). The model showed good calibration (Hosmer-Lemeshow goodness-of-fit, p = 0.816) with an AUC of 0.821 (95% CI: 0.775, 0.853). For the validation group, the AUC was 0.788 (95% CI: 0.732, 0.806).

CONCLUSION

Our predictive model can non-invasively assess the risk of OLM in patients with clinical stage IA-IIA ADC, enable surgeons perform an individualized prediction preoperatively, and assist the clinical decision-making procedure.

Utility of PET-CT in Newly Diagnosed HPV-Associated Oropharyngeal Squamous Cell Carcinoma

OBJECTIVE

To compare the utility of positron emission tomography-computed tomography (PET-CT) versus contrasted CT neck combined with routine chest imaging for disease staging and treatment planning in human papillomavirus (HPV) associated oropharyngeal squamous cell carcinoma (OPSCC) with clinically evident sites of primary disease.

METHODS

All adult patients with primary HPV-associated OPSCC at a single quaternary care cancer center from 2018 to 2019 were reviewed, and those with images available for re-review were included. Primary outcomes included concordance in clinical staging between the 2 imaging modalities of interest (PET-CT vs CT), as well as independent agreement of each with pathologic staging. Analysis was performed via ordinal logistic regression. A secondary outcome was treatment selection after diagnostic imaging, analyzed via chi-squared testing.

RESULTS

In total, 100 patients were included for evaluation, of which 89% were male, 91% Caucasian, and mean age was 61.2 years (SD 9.6). Clinical disease staging agreed between imaging modalities in 95% of cases (54 of 57 patients). Pathologic staging agreed with clinical staging from CT neck in 93% of cases (25 of 27 patients; P = .004), and with PET-CT in 82% (14 of 17 patients; P =.003). No differences were observed between the 2 imaging modalities for subsequent treatment selection (P = .39).

CONCLUSION

In uncomplicated HPV-associated OPSCC, CT offers equivalent diagnostic accuracy to that of combined whole-body PET-CT for clinical staging, and has no appreciable impact on treatment selection. A reduced reliance on routine PET-CT during initial workup of HPV-associated OPSCC may be favorable for otherwise healthy patients with clinically evident sites of primary disease.

Effectiveness of Head-and-Neck Molecular Imaging Reporting and Data System Criterion in Head-and-Neck Squamous Cell Carcinoma PostConcurrent Chemoradiotherapy

Purpose

Postconcurrent chemoradiotherapy (CRT) response assessment has been challenging in locally advanced head-and-neck squamous cell carcinoma (LA-HNSCC) due to prevailing postradiation changes. Molecular response methods have been encouraging, although further clarifications and validations were needed. We tested the effectiveness of a proposed semi-quantitative molecular response criterion in these patients.

Materials and Methods

Two subspecialty-trained physicians evaluated 18F-fluorodeoxyglucose positron emission tomography/computed tomography of LA-HNSCC patients (n = 83) post 3 months CRT using a five points Head and Neck Molecular Imaging-Reporting and Data System (HAN-MI-RADS) criterion. Where available, histopathology examination with clinical and imaging interpretation was taken as a reference for the disease. A diagnostic accuracy comparison was done with the existing Hopkins score. Further effectiveness was analyzed with disease-free survival (DFI) and overall survival (OS).

Results

Metastasis was developed in 11/83 patients at 3 months of evaluation. Of 72 patients, 39, 2, and 31 patients had a complete response, equivocal response, and partial response as per HAN-MI-RADS. Per patient sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for predicting loco-regional disease up to 1 and 2 years was 93.3%, 92.5%, 90.3%, 94.9%, 92.9%, and 84.9%, 91.9%, 90.3%, 87.2%, and 88.6% respectively. One year and two years DFI for each HAN-MI-RADS score showed a statistically significant difference while it was not for OS. The receiver operating characteristic curve analysis showed significantly better outcome predictability of HAN-MI-RADS (area under the curve [AUC] 0.884) than Hopkins (AUC 0.699).

Conclusions

A five points HAN-MI-RADS criterion was found promising for response assessment with less equivocal results and statistically significant higher AUC than Hopkins for loco-regional recurrence prediction.

Diagnostic Performance of Response Assessment FDG-PET/CECT in HNSCC Treated With Definitive Radio(chemo)therapy Using NI-RADS

OBJECTIVE

To assess the diagnostic performance of response assessment 18F-fluorodeoxyglucose positron emission tomography/contrast-enhanced computed tomography (FDG-PET/CECT) following definitive radio(chemo)therapy in head and neck squamous cell carcinoma (HNSCC) using Neck Imaging Reporting and Data System (NI-RADS).

STUDY DESIGN

A retrospective analysis from a prospectively maintained dataset.

SETTING

Tertiary-care comprehensive cancer center in a low-middle-income country.

METHODS

Adults with newly diagnosed, biopsy-proven, nonmetastatic HNSCC treated with definitive radio(chemo)therapy were included. Posttreatment response assessment FDG-PET/CECT scans were retrospectively assigned NI-RADS categories (1-3) for the primary site, neck, and both sites combined. Locoregional recurrence occurring within 2-years was defined as the event of interest. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy were calculated. Locoregional control stratified by NI-RADS categories was computed with the Kaplan-Meier method and compared using the log-rank test.

RESULTS

Posttreatment FDG-PET/CECT scans were available in 190 patients constituting the present study cohort. Sensitivity, specificity, PPV, NPV, and overall accuracy of the NI-RADS template for the primary site was 73.5%, 81.4%, 46.3%, 93.4%, and 80.0%, respectively. Similar metrics for the neck were 72.7%, 87.5%, 43.2%, 96.1%, and 85.8%, respectively. Combining primary site and neck, the corresponding metrics of diagnostic accuracy were 84.4%, 69.7%, 46.3%, 93.5%, and 73.2%, respectively. At a median follow-up of 40 months, Kaplan-Meier estimates of 2-year locoregional control were significantly higher for NI-RADS category 1 (94.2%) compared to NI-RADS category 2 (69.4%) and category 3 (20.4%), respectively (stratified log-rank p < .0001).

CONCLUSION

FDG-PET/CECT using the NI-RADS template is associated with good diagnostic performance and prognostic utility in HNSCC treated with definitive radio(chemo)therapy.

Importance of PET/CT in Initial Workup of Head and Neck Squamous Cell Carcinoma

Objective

Assess the impact of positron emission tomography/computed tomography (PET/CT) on disease staging at presentation in patients with head and neck squamous cell carcinoma.

Study Design

Retrospective cross-sectional review.

Setting

Academic multicenter single institution (Geisinger Health System).

Methods

All patients who had PET/CT imaging during workup for head and neck squamous cell carcinoma were included in the study. Pre- and post-PET/CT clinical staging were recorded. Statistical analyses were performed for patients with a change in clinical staging or detection of second primary malignancies on PET/CT.

Results

A total of 292 patients were included in the study, 238 of whom underwent PET/CT imaging as part of their initial workup. Twenty-eight (11.9%) patients were clinically upstaged on PET/CT with 7 patients having treatment alterations based on imaging. Eighteen (7.6%) patients were found to have second primary malignancies on PET/CT.

Conclusion

The current study further illustrates the importance of PET/CT in the workup of head and neck squamous cell carcinoma. Without the inclusion of PET/CT imaging, 19.3% of patients would have either been staged inappropriately or had second primary malignancies missed, again confirming the necessity of comprehensive functional imaging during the initial pretreatment workup.

The Prognostic and Diagnostic Value of [18F]FDG PET/CT in Untreated Laryngeal Carcinoma

This study aims to determine the diagnostic accuracy of staging PET/CT and neck MRI in patients with laryngeal carcinoma and to assess the value of PET/CT in predicting progression-free survival (PFS) and overall survival (OS). Sixty-eight patients who had both modalities performed before treatment between 2014 and 2021 were included in this study. The sensitivity and specificity of PET/CT and MRI were evaluated. PET/CT had 93.8% sensitivity, 58.3% specificity, and 75% accuracy for nodal metastasis, whereas MRI had 68.8%, 61.1%, and 64.7% accuracy, respectively. At a median follow-up of 51 months, 23 patients had developed disease progression and 17 patients had died. Univariate-survival analysis revealed all utilized PET parameters as significant prognostic factors for OS and PFS (p-value < 0.03 each). In multivariate analysis, metabolic-tumor volume (MTV) and total lesion glycolysis (TLG) predicted better PFS (p-value < 0.05 each). In conclusion, PET/CT improves the accuracy of nodal staging in laryngeal carcinoma over neck MRI and adds to the prognostication of survival outcomes through the use of several PET metrics.

Towards reliable head and neck cancers locoregional recurrence prediction using delta-radiomics and learning with rejection option

PURPOSE

A reliable locoregional recurrence (LRR) prediction model is important for the personalized management of head and neck cancers (HNC) patients who received radiotherapy. This work aims to develop a delta-radiomics feature-based multi-classifier, multi-objective, and multi-modality (Delta-mCOM) model for post-treatment HNC LRR prediction. Furthermore, we aim to adopt a learning with rejection option (LRO) strategy to boost the reliability of Delta-mCOM model by rejecting prediction for samples with high prediction uncertainties.

METHODS

In this retrospective study, we collected PET/CT image and clinical data from 224 HNC patients who received radiotherapy (RT) at our institution. We calculated the differences between radiomics features extracted from PET/CT images acquired before and after radiotherapy and used them in conjunction with pre-treatment radiomics features as the input features. Using clinical parameters, PET radiomics features, and CT radiomics features, we built and optimized three separate single-modality models. We used multiple classifiers for model construction and employed sensitivity and specificity simultaneously as the training objectives for each of them. Then, for testing samples, we fused the output probabilities from all these single-modality models to obtain the final output probabilities of the Delta-mCOM model. In the LRO strategy, we estimated the epistemic and aleatoric uncertainties when predicting with a trained Delta-mCOM model and identified patients associated with prediction of higher reliability (low uncertainty estimates). The epistemic and aleatoric uncertainties were estimated using an AutoEncoder-style anomaly detection model and test-time augmentation (TTA) with predictions made from the Delta-mCOM model, respectively. Predictions with higher epistemic uncertainty or higher aleatoric uncertainty than given thresholds were deemed unreliable, and they were rejected before providing a final prediction. In this study, different thresholds corresponding to different low-reliability prediction rejection ratios were applied. Their values are based on the estimated epistemic and aleatoric uncertainties distribution of the validation data.

RESULTS

The Delta-mCOM model performed significantly better than the single-modality models, whether trained with pre-, post-treatment radiomics features or concatenated BaseLine and Delta-Radiomics Features (BL-DRFs). It was numerically superior to the PET and CT fused BL-DRF model (nonstatistically significant). Using the LRO strategy for the Delta-mCOM model, most of the evaluation metrics improved as the rejection ratio increased from 0% to around 25%. Utilizing both epistemic and aleatoric uncertainty for rejection yielded nonstatistically significant improved metrics compared to each alone at approximately a 25% rejection ratio. Metrics were significantly better than the no-rejection method when the reject ratio was higher than 50%.

CONCLUSIONS

The inclusion of the delta-radiomics feature improved the accuracy of HNC LRR prediction, and the proposed Delta-mCOM model can give more reliable predictions by rejecting predictions for samples of high uncertainty using the LRO strategy.

Advanced imaging of head and neck infections

When head and neck infection is suspected, appropriate imaging contributes to treatment decisions and prognosis. While contrast-enhanced CT is the standard imaging modality for evaluating head and neck infections, MRI can better characterize the skull base, intracranial involvement, and osteomyelitis, implying that these are complementary techniques for a comprehensive assessment. Both CT and MRI are useful in the evaluation of abscesses and thrombophlebitis, while MRI is especially useful in the evaluation of intracranial inflammatory spread/abscess formation, differentiation of abscess from other conditions, evaluation of the presence and activity of inflammation and osteomyelitis, evaluation of mastoid extension in middle ear cholesteatoma, and evaluation of facial neuritis and labyrinthitis. Apparent diffusion coefficient derived from diffusion-weighted imaging is useful for differential diagnosis and treatment response of head and neck infections in various anatomical sites. Dynamic contrast-enhanced MRI perfusion may be useful in assessing the activity of skull base osteomyelitis. MR bone imaging may be of additional value in evaluating bony structures of the skull base and jaw. Dual-energy CT is helpful in reducing metal artifacts, evaluating deep neck abscess, and detecting salivary stones. Subtraction CT techniques are used to detect progressive bone-destructive changes and to reduce dental amalgam artifacts. This article provides a region-based approach to the imaging evaluation of head and neck infections, using both conventional and advanced imaging techniques.

Imaging Approach for Cervical Lymph Node Metastases from Unknown Primary Tumor

Neck swelling due to lymph node (LN) metastasis is one of the initial symptoms of head and neck cancer, and in some cases, the primary tumor is not clinically evident. The purpose of imaging for LN metastasis from an unknown primary site is to identify the primary tumor or detect its absence, which leads to the correct diagnosis and optimal treatment. The authors discuss diagnostic imaging approaches for identifying the primary tumor in cases of unknown primary cervical LN metastases. The distribution and characteristics of LN metastases may help locate the primary site. Unknown primary LN metastasis often occurs at nodal levels II and III, and in recent reports, these were mostly related to human papillomavirus (HPV)-positive squamous cell carcinoma of the oropharynx. Another characteristic imaging finding suggestive of metastasis from HPV-associated oropharyngeal cancer is a cystic change in LN metastases. Other characteristic imaging findings such as calcification may help predict the histologic type and locate the primary site. In cases of LN metastases at nodal levels IV and VB, a primary lesion located outside the head and neck region must also be considered. One clue for detecting the primary lesion at imaging is the disruption of anatomic structures, which can help in identifying small mucosal lesions or submucosal tumors at each subsite. Additionally, fluorine 18 fluorodeoxyglucose PET/CT may help identify a primary tumor. These imaging approaches for identifying primary tumors enable prompt identification of the primary site and assist clinicians in making the correct diagnosis. ^© RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

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

CT, MRI, and FDG PET/CT play major roles in the diagnosis, staging, treatment planning, and surveillance of head and neck cancers. Nonetheless, an evolving understanding of head and neck cancer pathogenesis, advances in imaging techniques, changing treatment regimens, and a lack of standardized guidelines have led to areas of uncertainty in the imaging of head and neck cancer. This narrative review aims to address four issues in the contemporary imaging of head and neck cancer. The first issue relates to the standard and advanced sequences that should be included in MRI protocols for head and neck cancer imaging. The second issue relates to approaches to surveillance imaging after treatment of head and neck cancer, including the choice of imaging modality, the frequency of surveillance imaging, and the role of standardized reporting through the Neck Imaging Reporting and Data System. The third issue relates to the role of imaging in the setting of neck carcinoma of unknown primary. The fourth issue relates to the role of simultaneous PET/MRI in head and neck cancer evaluation. The authors of this review provide consensus opinions for each issue.

89Zr-panitumumab Combined With 18F-FDG PET Improves Detection and Staging of Head and Neck Squamous Cell Carcinoma

PURPOSE

Determine the safety and specificity of a tumor-targeted radiotracer (89Zr-pan) in combination with 18F-FDG PET/CT to improve diagnostic accuracy in head and neck squamous cell carcinoma (HNSCC).

EXPERIMENTAL DESIGN

Adult patients with biopsy-proven HNSCC scheduled for standard-of-care surgery were enrolled in a clinical trial and underwent systemic administration of 89Zirconium-panitumumab and panitumumab-IRDye800 followed by preoperative 89Zr-pan PET/CT and intraoperative fluorescence imaging. The sensitivity, specificity, and AUC were evaluated.

RESULTS

A total of fourteen patients were enrolled and completed the study. Four patients (28.5%) had areas of high 18F-FDG uptake outside the head and neck region with maximum standardized uptake values (SUVmax) greater than 2.0 that were not detected on 89Zr-pan PET/CT. These four patients with incidental findings underwent further workup and had no evidence of cancer on biopsy or clinical follow-up. Forty-eight lesions (primary tumor, LNs, incidental findings) with SUVmax ranging 2.0-23.6 were visualized on 18F-FDG PET/CT; 34 lesions on 89Zr-pan PET/CT with SUVmax ranging 0.9-10.5. The combined ability of 18F-FDG PET/CT and 89Zr-pan PET/CT to detect HNSCC in the whole body was improved with higher specificity of 96.3% [confidence interval (CI), 89.2%-100%] compared to 18F-FDG PET/CT alone with specificity of 74.1% (CI, 74.1%-90.6%). One possibly related grade 1 adverse event of prolonged QTc (460 ms) was reported but resolved in follow-up.

CONCLUSIONS

89Zr-pan PET/CT imaging is safe and may be valuable in discriminating incidental findings identified on 18F-FDG PET/CT from true positive lesions and in localizing metastatic LNs.

Predicting local persistence/recurrence after radiation therapy for head and neck cancer from PET/CT using a multi-objective, multi-classifier radiomics model

Objectives

Accurate identifying head and neck squamous cell cancer (HNSCC) patients at high risk of local persistence/recurrence (P/R) is of importance for personalized patient management. Here we developed a multi-objective, multi-classifier radiomics model for early HNSCC local P/R prediction based on post-treatment PET/CT scans and clinical data.

Materials and methods

We retrospectively identified 328 individuals (69 patients have local P/R) with HNSCC treated with definitive radiation therapy at our institution. The median follow-up from treatment completion to the first surveillance PET/CT imaging was 114 days (range: 82-159 days). Post-treatment PET/CT scans were reviewed and contoured for all patients. For each imaging modality, we extracted 257 radiomic features to build a multi-objective radiomics model with sensitivity, specificity, and feature sparsity as objectives for model training. Multiple representative classifiers were combined to construct the predictive model. The output probabilities of models built with features from various modalities were fused together to make the final prediction.

Results

We built and evaluated three single-modality models and two multi-modality models. The combination of PET, CT, and clinical data in the multi-objective, multi-classifier radiomics model trended towards the best prediction performance, with a sensitivity of 93%, specificity of 83%, accuracy of 85%, and AUC of 0.94.

Conclusion

Our study demonstrates the feasibility of employing a multi-objective, multi-classifier radiomics model with PET/CT radiomic features and clinical data to predict outcomes for patients with HNSCC after radiation therapy. The proposed prediction model shows the potential to detect cancer local P/R early after radiation therapy.

Imaging of human papilloma virus associated oropharyngeal squamous cell carcinoma and its impact on diagnosis, prognostication, and response assessment

The clinical behaviour and outcomes of patients with oropharyngeal cancer (OPC) may be dichotomised according to their association with human papilloma virus (HPV) infection. Patients with HPV-associated disease (HPV+OPC) have a distinct demographic profile, clinical phenotype and demonstrate considerably better responses to chemoradiotherapy. This has led to a reappraisal of staging and treatment strategies for HPV+OPC, which are underpinned by radiological data. Structural modalities, such as CT and MRI can provide accurate staging information. These can be combined with ultrasound-guided tissue sampling and functional techniques (such as diffusion-weighted MRI and 18F-fludeoxyglucose positron emission tomography-CT) to monitor response to treatment, derive prognostic information, and to identify individuals who might benefit from intensification or deintensification strategies. Furthermore, advanced MRI techniques, such as intravoxel incoherent motion and perfusion MRI as well as application of artificial intelligence and radiomic techniques, have shown promise in treatment response monitoring and prognostication. The following review will consider the contemporary role and knowledge on imaging in HPV+OPC.

Histogram analysis of 18F-FDG PET imaging SUVs may predict the histologic grade of oral squamous cell carcinoma

OBJECTIVE

We tested the hypothesis that histogram analysis parameters of standardized uptake values (SUVs) obtained preoperatively using ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) are significantly influenced by differences in metabolic capacity due to the histologic grade of oral squamous cell carcinoma (OSCC).

STUDY DESIGN

The study included 62 patients who were clinically diagnosed with OSCC and received surgical treatment after an ¹⁸F-FDG PET examination. Histogram analysis was performed using all voxels contained in the tumor area of each patient with an SUV ≥2.5. The histogram parameters calculated were the mean and standard deviation of SUVs, maximum SUV, metabolic tumor volume, skewness, and kurtosis. Statistical analyses were performed using a Mann-Whitney U test to calculate the significance of differences in these parameters between groups with well- and moderately- or poorly-differentiated tumors. Statistical significance was assumed at P < .05.

RESULTS

Only a comparison of kurtosis in the histogram showed a significant difference between the well- and moderately/poorly-differentiated tumors (P = .0294).

CONCLUSIONS

The distribution of metabolic capacity in oral squamous cell carcinoma tissues revealed on an ¹⁸F-FDG PET examination may help identify the histologic grade. This finding may provide valuable information for determining the subsequent treatment plan and predicting disease prognosis.

Progression Free Survival Prediction for Head and Neck Cancer Using Deep Learning Based on Clinical and PET/CT Imaging Data

Determining progression-free survival (PFS) for head and neck squamous cell carcinoma (HNSCC) patients is a challenging but pertinent task that could help stratify patients for improved overall outcomes. PET/CT images provide a rich source of anatomical and metabolic data for potential clinical biomarkers that would inform treatment decisions and could help improve PFS. In this study, we participate in the 2021 HECKTOR Challenge to predict PFS in a large dataset of HNSCC PET/CT images using deep learning approaches. We develop a series of deep learning models based on the DenseNet architecture using a negative log-likelihood loss function that utilizes PET/CT images and clinical data as separate input channels to predict PFS in days. Internal model validation based on 10-fold cross-validation using the training data (N = 224) yielded C-index values up to 0.622 (without) and 0.842 (with) censoring status considered in C-index computation, respectively. We then implemented model ensembling approaches based on the training data cross-validation folds to predict the PFS of the test set patients (N = 101). External validation on the test set for the best ensembling method yielded a C-index value of 0.694, placing 2^nd in the competition. Our results are a promising example of how deep learning approaches can effectively utilize imaging and clinical data for medical outcome prediction in HNSCC, but further work in optimizing these processes is needed.

Tetraspanin CD9: A friend or foe of head and neck cancer (Review)

Head and neck cancers are diverse and complex diseases characterised by unregulated growth of tumour cells in various parts of the head and neck region, such as in the buccal mucosa, floor of the mouth, tongue, oropharynx, hypopharynx, oesophagus, nasopharynx and salivary glands. Partial or total glossectomy, radiation or chemotherapy greatly affect patient quality of life. However, even following treatment, patients may relapse. Nicotine-derived nitrosamines and alcohol are the major etiological factors underlying this deadly disease. These compounds induce DNA damage that may lead to mutation in crucial genes, such as p53 and p21, which are important to regulate cell proliferation, thus leading to cancer. CD9 is a tetraspanin, which are a group of transmembrane proteins that have a role in cell motility and adhesion. The present review aimed to explore the role of CD9 in head and neck cancer. Epidermal growth factor receptor activity and cell proliferation are regulated by the CD9-integrin/CD9-transforming growth factor interaction. Hence, CD9 can play a dual role in various types of cancer.

PET/MR Imaging in Evaluating Treatment Failure of Head and Neck Malignancies: A Neck Imaging Reporting and Data System-Based Study

BACKGROUND AND PURPOSE

PET/MR imaging is a relatively new hybrid technology that holds great promise for the evaluation of head and neck cancer. The aim of this study was to assess the performance of simultaneous PET/MR imaging versus MR imaging in the evaluation of posttreatment head and neck malignancies, as determined by its ability to predict locoregional recurrence or progression after imaging.

MATERIALS AND METHODS

The electronic medical records of patients who had posttreatment PET/MR imaging studies were reviewed, and after applying the exclusion criteria, we retrospectively included 46 studies. PET/MR imaging studies were independently reviewed by 2 neuroradiologists, who recorded scores based on the Neck Imaging Reporting and Data System (using CT/PET-CT criteria) for the diagnostic MR imaging sequences alone and the combined PET/MR imaging. Treatment failure was determined with either biopsy pathology or initiation of new treatment. Statistical analyses including univariate association, interobserver agreement, and receiver operating characteristic analysis were performed.

RESULTS

There was substantial interreader agreement among PET/MR imaging scores (κ = 0.634; 95% CI, 0.605-0.663). PET/MR imaging scores showed a strong association with treatment failure by univariate association analysis, with P < .001 for the primary site, neck lymph nodes, and combined sites. Receiver operating characteristic curves of PET/MR imaging scores versus treatment failure indicated statistically significant diagnostic accuracy (area under curve range, 0.864-0.987; P < .001).

CONCLUSIONS

Simultaneous PET/MR imaging has excellent discriminatory performance for treatment outcomes of head and neck malignancy when the Neck Imaging Reporting and Data System is applied. PET/MR imaging could play an important role in surveillance imaging for head and neck cancer.

Detailed patient-individual reporting of lymph node involvement in oropharyngeal squamous cell carcinoma with an online interface

PURPOSE/OBJECTIVE

Whereas the prevalence of lymph node level (LNL) involvement in head & neck squamous cell carcinomas (HNSCC) has been reported, the details of lymphatic progression patterns are insufficiently quantified. In this study, we investigate how the risk of metastases in each LNL depends on the involvement of upstream LNLs, T-category, HPV status and other risk factors.

MATERIALS/METHODS

We retrospectively analyzed patients with newly diagnosed oropharyngeal squamous cell carcinoma (OPSCC) treated at a single institution, resulting in a dataset of 287 patients. For all patients, involvement of LNLs I-VII was recorded individually based on available diagnostic modalities (PET, MR, CT, FNA) together with clinicopathological factors. To analyze the dataset, a web-based graphical user interface (GUI) was developed, which allows querying the number of patients with a certain combination of co-involved LNLs and tumor characteristics.

RESULTS

The full dataset and GUI is part of the publication. Selected findings are: Ipsilateral level IV was involved in 27% of patients with level II and III involvement, but only in 2% of patients with level II but not III involvement. Prevalence of involvement of ipsilateral levels II, III, IV, V was 79%, 34%, 7%, 3% for early T-category patients (T1/T2) and 85%, 50%, 17%, 9% for late T-category (T3/T4), quantifying increasing involvement with T-category. Contralateral levels II, III, IV were involved in 41%, 19%, 4% and 12%, 3%, 2% for tumors for tumors with and without midline extension, respectively. T-stage dependence of LNL involvement was more pronounced in HPV negative than positive tumors, but overall involvement was similar. Ipsilateral level VII was involved in 14% and 6% of patients with primary tumors in the tonsil and the base of tongue, respectively.

CONCLUSIONS

Detailed quantification of LNL involvement in HNSCC depending on involvement of upstream LNLs and clinicopathological factors may allow for further personalization of CTV-N definition in the future.

18F-FDG PET cannot predict expression of clinically relevant histopathological biomarkers in head and neck squamous cell carcinoma: a meta-analysis

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is a common cancer. Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) is a widely used imaging modality in HNSCC.

PURPOSE

To provide evident data about associations between 18F-FDG PET and histopathology in HNSCC.

MATERIAL AND METHODS

The MEDLINE database was screened for associations between maximum standard uptake values (SUV_max) derived from 18F-FDG PET and histopathological features in HNSCC up to May 2020. Only papers containing correlation coefficients between SUV_max and histopathology were acquired. Overall, 23 publications were collected.

RESULTS

The following correlations were calculated: KI 67: 12 studies (345 patients), pooled correlation coefficient (PCC): 0.23 (95% confidence interval [CI] 0.06-0.40); hypoxia-inducible factor-1α: eight studies (240 patients), PCC: 0.24 (95% CI 0.06-0.42); microvessel density: three studies (64 patients), PCC: 0.33 (95% CI 0.02-0.65); vascular endothelial growth factor: two studies (59 cases), PCC: 0.27 (95% CI 0.02-0.51); tumor suppressor protein p53: four studies (159 patients), PCC: 0.05 (95% CI -0.41 to 0.51); epidermal growth factor receptor: two studies (124 patients), PCC: 0.21 (95% CI 0.05-0.37); tumor cell count: three studies (67 patients), PCC: 0.18 (95% CI -0.06 to 0.42); tumor cell apoptosis: two studies (40 patients), PCC: 0.07 (95% CI = -0.85 to 0.99); B-cell lymphoma-2 protein: two studies (118 patients); PCC: 0.04 (95% CI -0.65 to 0.74); glucose-transporter 1: 10 studies (317 patients), PCC: 0.20 (95% CI 0.10-0.30).

CONCLUSION

SUV_max derived from 18F-FDG PET cannot reflect relevant histopathological features in HNSCC.

Single photon emission computed tomography-computed tomography visualization of sentinel lymph nodes for lymph flow guided nodal irradiation in oral tongue cancer

PURPOSE

To evaluate correlation of single photon emission computed tomography-computed tomography (SPECT-CT) data on lymph flow (LF) from oral tongue cancer (OC) and the topography of lymph nodes (LN) metastases; to determine the clinical value of lymph flow guided radiotherapy (LFGRT).

MATERIALS AND METHODS

SPECT-CT visualization of LF from the OC lesions was performed after peritumoral injection of 99mTc-phytate in 26 primary patients with clinical stage cT1-2N0M0 disease. We determined the individual drainage (unilateral/bilateral) from the tumor, and localization of sentinel LNs according to the neck levels. Metastases in LNs were verified with histology and a 2-year follow-up.

RESULTS

SPECT-CT detected bilateral LF in 10 (38.5%) of 26 patients; in 16 (61.5%) cases the drainage was unilateral. Histology revealed LNs metastases in three cases; regional recurrences were diagnosed in other four patients. In all seven observations metastases were located at the same site and level as the sentinel LNs. In eight (30.8%) of 26 patients sentinel LNs were visualized unilaterally at levels Ib-IIa; in five cases, unilaterally at levels I-IIa-III. In these patients, LFGRT demonstrated 59%-70% reduction of irradiated volume, and 26%-42% and 51%-70% decrease of the mean dose to the spinal cord and the contralateral parotid gland. In patients with a bilateral drainage the reduction of doses absorbed by the spinal cord and contralateral parotid gland was 19% and 6%, respectively.

CONCLUSION

Localization of sentinel LNs determined by SPECT-CT corresponds to the localization of metastatic LNs in terms of side and levels.

The Added Value of 68Ga-FAPI-04 PET/CT in Patients with Head and Neck Cancer of Unknown Primary with 18F-FDG Negative Findings

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) plays an important role in locating of primary tumor for patients with head and neck cancer of unknown primary (HNCUP). Nevertheless, it can be challenging to locate the primary malignancy in ¹⁸F-FDG-PET/CT scan in some cases. As ⁶⁸Ga-radiolabeled fibroblast activation protein inhibitor (FAPI) PET/CT has promising results in detecting different tumor entities, our study aimed to evaluate the performance of ⁶⁸Ga-FAPI-PET/CT for detecting the primary tumor in HNCUP patients with negative ¹⁸F-FDG findings. Methods: A total of eighteen patients (16 males and 2 females; median age, 55 years; range, 24-72 years) with negative ¹⁸F-FDG findings were enrolled in this study. All patients underwent ¹⁸F-FDG and ⁶⁸Ga-FAPI-PET/CT within one week. Biopsy and histopathological examinations were done in the sites with positive ⁶⁸Ga-FAPI-PET/CT findings. Results: ⁶⁸Ga-FAPI-PET/CT detected the primary tumor in 7 out of 18 patients (38.89%). Among the 7 patients, in respect of the primary tumor sites, 1 was in nasopharynx, 2 were in palatine tonsil, 2 were in submandibular gland, and 2 were in hypopharynx. The primary tumors showed moderate to intensive uptake of FAPI (mean SUV_max, 8.79; range, 2.60-16.50) and excellent tumor-to-contralateral normal tissue ratio (mean SUV_max ratio, 4.50; range, 2.17-8.21). In lesion-based analysis, a total of 65 lymph nodes and 17 bone metastatic lesions were identified. The mean SUV_max of lymph node metastases were 9.05 ± 5.29 for FDG and 9.08 ± 4.69 for FAPI (P = 0.975); as for bone metastases, the mean SUV_max were 8.11 ± 3.00 for FDG and 6.96 ± 5.87 for FAPI, respectively (P = 0.478). The mean tumor-to-background ratio (TBR) values of lymph node and bone metastases were 10.65 ± 6.59 vs. 12.80 ± 8.11 (P = 0.100) and 9.08 ± 3.35 vs. 9.14 ± 8.40 (P = 0.976), respectively. Conclusion: We presented first evidence of diagnostic role of ⁶⁸Ga-FAPI-PET/CT in HNCUP, and our study demonstrated that ⁶⁸Ga-FAPI-PET/CT had the potential to improve the detection rate of primary tumor in HNCUP patients with negative FDG findings. Moreover, ⁶⁸Ga-FAPI had similar performance in assessing metastases with ¹⁸F-FDG.

Risk Stratification Using 18F-FDG PET/CT and Artificial Neural Networks in Head and Neck Cancer Patients Undergoing Radiotherapy

This study retrospectively analyzed the performance of artificial neural networks (ANN) to predict overall survival (OS) or locoregional failure (LRF) in HNSCC patients undergoing radiotherapy, based on 2-[¹⁸F]FDG PET/CT and clinical covariates. We compared predictions relying on three different sets of features, extracted from 230 patients. Specifically, (i) an automated feature selection method independent of expert rating was compared with (ii) clinical variables with proven influence on OS or LRF and (iii) clinical data plus expert-selected SUV metrics. The three sets were given as input to an artificial neural network for outcome prediction, evaluated by Harrell’s concordance index (HCI) and by testing stratification capability. For OS and LRF, the best performance was achieved with expert-based PET-features (0.71 HCI) and clinical variables (0.70 HCI), respectively. For OS stratification, all three feature sets were significant, whereas for LRF only expert-based PET-features successfully classified low vs. high-risk patients. Based on 2-[¹⁸F]FDG PET/CT features, stratification into risk groups using ANN for OS and LRF is possible. Differences in the results for different feature sets confirm the relevance of feature selection, and the key importance of expert knowledge vs. automated selection.

Application of Community Detection Algorithm to Investigate the Correlation between Imaging Biomarkers of Tumor Metabolism, Hypoxia, Cellularity, and Perfusion for Precision Radiotherapy in Head and Neck Squamous Cell Carcinomas

The present study aimed to investigate the correlation at pre-treatment (TX) between quantitative metrics derived from multimodality imaging (MMI), including 18F-FDG-PET/CT, 18F-FMISO-PET/CT, DW- and DCE-MRI, using a community detection algorithm (CDA) in head and neck squamous cell carcinoma (HNSCC) patients. Twenty-three HNSCC patients with 27 metastatic lymph nodes underwent a total of 69 MMI exams at pre-TX. Correlations among quantitative metrics derived from FDG-PET/CT (SUL), FMSIO-PET/CT (K1, k3, TBR, and DV), DW-MRI (ADC, IVIM [D, D*, and f]), and FXR DCE-MRI [Ktrans, ve, and τi]) were investigated using the CDA based on a "spin-glass model" coupled with the Spearman's rank, ρ, analysis. Mean MRI T2 weighted tumor volumes and SULmean values were moderately positively correlated (ρ = 0.48, p = 0.01). ADC and D exhibited a moderate negative correlation with SULmean (ρ ≤ -0.42, p < 0.03 for both). K1 and Ktrans were positively correlated (ρ = 0.48, p = 0.01). In contrast, Ktrans and k3max were negatively correlated (ρ = -0.41, p = 0.03). CDA revealed four communities for 16 metrics interconnected with 33 edges in the network. DV, Ktrans, and K1 had 8, 7, and 6 edges in the network, respectively. After validation in a larger population, the CDA approach may aid in identifying useful biomarkers for developing individual patient care in HNSCC.

Skeletal muscle mass at C3 may not be a strong predictor for skeletal muscle mass at L3 in sarcopenic patients with head and neck cancer

PURPOSE

To evaluate the feasibility of using skeletal muscle mass (SMM) at C3 (C3 SMM) as a diagnostic marker for sarcopenia in head and neck cancer (HNC) patients.

METHODS

We evaluated 165 HNC patients and 42 healthy adults who underwent 18F-fluorodeoxyglucose positron emission tomography/computed tomography scans. The paravertebral muscle area at C3 and skeletal muscle area at L3 were measured by CT. Pearson's correlation was used to assess the relationship between L3 and C3 SMMs. The prediction model for L3 SMM was developed by multiple linear regression. Then the correlation and the agreement between actual and predicted L3 SMMs were assessed. To evaluate the diagnostic value of C3 SMM for sarcopenia, the receiver operating characteristics (ROC) curves were analyzed.

RESULTS

Of the 165 HNC patients, 61 (37.0%) were sarcopenic and 104 (63.0%) were non-sarcopenic. A very strong correlation was found between L3 SMM and C3 SMM in both healthy adults (r = 0.864) and non-sarcopenic patients (r = 0.876), while a fair association was found in sarcopenic patients (r = 0.381). Prediction model showed a very strong correlation between actual SMM and predicted L3 SMM in both non-sarcopenic patients and healthy adults (r > 0.9), whereas the relationship was moderate in sarcopenic patients (r = 0.7633). The agreement between two measurements was good for healthy subjects and non-sarcopenic patients, while it was poor for sarcopenic patients. On ROC analysis, predicted L3 SMM showed poor diagnostic accuracy for sarcopenia.

CONCLUSIONS

A correlation between L3 and C3 SMMs was weak in sarcopenic patients. A prediction model also showed a poor diagnostic accuracy. Therefore, C3 SMM may not be a strong predictor for L3 SMM in sarcopenic patients with HNC.

Radiologic Evaluation of the Head and Neck Cancer Patient

CT, PET, ultrasound, and MRI examinations all have roles in the staging and surveillance of cancers in the head and neck. Contrast-enhanced CT is generally the primary examination because of availability, cost, reproducibility, and good overall quality regardless of where performed. PET, ultrasound, and MRI have more specific and nuanced applications. Good interdisciplinary interactions with radiologist consultation can streamline the examination process and reduce the examination burden on patients by limiting the number and maximizing the quality of the examinations and image-guided interventions performed.

PET/CT Variants and Pitfalls in Head and Neck Cancers Including Thyroid Cancer

PET/CT imaging is a dual-modality diagnostic technology that merges metabolic and structural imaging. There are several currently available radiotracers, but ¹⁸F-FDG is the most commonly utilized due to its widespread availability. ¹⁸F-FDG PET/CT is a cornerstone of head and neck squamous cell carcinoma imaging. ⁶⁸Ga-DOTA-TOC is another widely used radiotracer. It allows for whole-body imaging of cellular somatostatin receptors, commonly expressed by neuroendocrine tumors and is the standard of reference for the characterization and staging of neuroendocrine tumors. The normal biodistribution of these PET radiotracers as well as the technical aspects of image acquisition and inadequate patient preparation affect the quality of PET/CT imaging. In addition, normal variants, artifacts and incidental findings may impede accurate image interpretation and can potentially lead to misdiagnosis. In order to correctly interpret PET/CT imaging, it is necessary to have a comprehensive knowledge of the normal anatomy of the head and neck and to be cognizant of potential imaging pitfalls. The interpreter must be familiar with benign conditions which may accumulate radiotracer potentially mimicking neoplastic processes and also be aware of malignancies which can demonstrate low radiotracer uptake. Appropriate use of structural imaging with either CT, MR or ultrasound can serve a complimentary role in several head and neck pathologies including local tumor staging, detection of bone marrow involvement or perineural spread, and classification of thyroid nodules. It is important to be aware of the role of these complementary modalities to maximize diagnostic accuracy and patient outcomes. The purpose of this article is to outline the basic principles of PET/CT imaging, with a focus on ¹⁸F-FDG PET/CT and ⁶⁸Ga-DOTA PET/CT. Basic physiology, variant imaging appearances and potential pitfalls of image interpretation are presented within the context of common use cases of PET technology in patients with head and neck cancers and other pathologies, benign and malignant.

Best Practices: Application of NI-RADS for Posttreatment Surveillance Imaging of Head and Neck Cancer

Imaging surveillance is an important component of posttreatment management of head and neck cancers. There is variability in the surveillance regimen used by various practitioners and institutions, with no official National Comprehensive Cancer Network guidelines for patients showing no symptoms beyond 6 months posttreatment. Moreover, imaging of the neck after treatment is a complex examination with significant interreader heterogeneity, particularly in terms of the manner in which degree of suspicion for disease recurrence is expressed. The Neck Imaging Reporting and Data System (NI-RADS) was introduced by the American College of Radiology (ACR) in 2018 as a practical guide for the interpreting radiologist. NI-RADS is a proposed interpretive framework that can be applied to any standardized or institutional surveillance imaging protocol. NI-RADS simplifies communication between radiologists and referring clinicians and provides management guidance linked to specific levels of suspicion. The ACR NI-RADS Committee also provided general best practice recommendations for imaging surveillance modality and timing in the 2018 white paper. This article will review existing literature regarding choice of modality and timeline for surveillance in treated cancer of the head and neck. NI-RADS will then be presented as an approach to imaging reporting, interpretation, and design of next steps in management.

Diagnostic and Prognostic Utility of 18F-FDG PET/CT in Recurrent Salivary Gland Cancers

OBJECTIVE. The role of ¹⁸F-FDG PET/CT in the evaluation of recurrent salivary gland tumors remains poorly defined. We investigated the diagnostic and prognostic utility of PET in this setting. MATERIALS AND METHODS. A total of 146 patients with recurrent salivary gland cancer were treated at our institution between January 2002 and December 2015. Patients who underwent FDG PET/CT and conventional imaging (CT or MRI) within 3 months of recurrence (n = 78) were included in this retrospective analysis. On FDG PET/CT, we measured the SUV_max, total body metabolic tumor volume of all lesions, and total lesion glycolysis of all lesions to determine the intensity and extent of FDG-avid disease. We assessed the correlation of FDG PET/CT findings with clinicopathologic features, progression-free survival, and overall survival. RESULTS. FDG PET/CT was positive for recurrence in 74 of 78 patients (94.9%) and falsely negative in four patients (5.1%). In comparison with conventional imaging, FDG PET/CT performed for restaging detected additional recurrent lesions in 14 patients (17.9%). The median SUV_max was 7.4, the median total body metabolic tumor volume was 30.1 cm³, and median total lesion glycolysis was 97.3 g/mL × cm³. Sixty-six patients had progressive disease, and 54 died. Univariate and multivariate Cox hazards analysis identified pathologic risk group (p = .04), total body metabolic tumor volume (p < .001), and total lesion glycolysis (p < .001) as independent prognostic factors for progression-free survival and identified age (p = .05), total body metabolic tumor volume (p < .001), and total lesion glycolysis (p < .001) as independent prognostic factors for overall survival. CONCLUSION. In patients with recurrent salivary gland cancer, FDG PET/CT is useful as a single test for defining the extent of disease and providing prognostic information, which may help in selecting appropriate treatment strategies.

Percutaneous Management of Recurrent Head and Neck Cancer: Current Role and Evolving Principles in the Multidisciplinary Setting

PURPOSE OF REVIEW

In this review, we will outline the role of percutaneous interventional radiological management of recurrent head and neck (H&N) cancer in the context of a multidisciplinary setting which consists of surgery, radiation therapy, as well as established and evolving systemic therapies that may impact current practice.

RECENT FINDINGS

Management of recurrent H&N cancer is complex, with attention to the preservation of function and minimal treatment-related morbidity. The favored treatment modalities in local recurrence previously treated with radiotherapy are surgical resection, and if unresectable, for chemotherapy as definitive treatment, or as a prelude to resection if there is good tumor response. Unfortunately, some of these patients are too frail for major surgery or to withstand the toxicity of chemotherapy. There is a gap for effective local therapy without the morbidity of surgery, toxicity of re-irradiation, and systemic side effects of chemotherapy. Percutaneous interventions have the potential to bridge that gap as well as provide palliative symptomatic treatment for patients that have exhausted all treatment options. In the multidisciplinary setting involving the treatment of complex recurrent H&N cancer, percutaneous management now plays a viable and effective role with a foothold in this team-based approach.

18F-FDG-PET/CT in laryngeal cancer: Comparison with conventional imaging and prognostic role

OBJECTIVE

The aim of this study was to investigate the diagnostic accuracy of staging ¹⁸F-FDG-PET/CT in laryngeal cancer, compare these results with conventional imaging (CI) and assess the value of ¹⁸F-FDG-PET/CT features to predict survival.

METHODS

Fifty-four patients with laryngeal squamous cell cancer and baseline ¹⁸F-FDG-PET/CT were retrospectively enrolled. The PET images were analyzed visually and semi-quantitatively by measuring several metabolic parameters. A combination of clinical follow-up/imaging follow-up and/or histopathology was taken as reference standard. Progression free survival (PFS) and disease specific survival (DSS) were computed using Kaplan-Meier curves.

RESULTS

All primary tumors were clearly identified by CI, and 52/54 by ¹⁸F-FDG-PET/CT with a sensitivity of 96.3%. Cervical nodal metastases were detected in 40/54 patients at ¹⁸F-FDG-PET/CT and in 34/49 patients at CI. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy on a patient-based analysis for nodal disease were 100%, 85.7%, 94.6%, 100% and 95.9% at ¹⁸F-FDG-PET/CT, and 91.4%, 85.7%, 94.1%, 80%, 89.8% at CI. Diagnostic performances of PET/CT and CI were not significantly different on a patient-based, side-by-side and level-by-level analysis. ¹⁸F-FDG-PET/CT recognized distant metastases in 7 patients allowing to an upstaging. At a median follow-up of 27 months, relapse/progression of disease occurred in 31 patients and death occurred in 32. Metabolic tumor volume (MTV T), MTV total and total lesion glycolysis (TLG) showed to be independent prognostic factors for PFS.

CONCLUSIONS

Both CI and PET/CT had good diagnostic performances for the staging of laryngeal cancer; baseline metabolic features (MTV and TLG) showed an important prognostic value in assessing the rate of PFS.

Oligometastases in head and neck carcinoma and their impact on management

Historically, patients with head and neck squamous cell carcinoma (HNSCC) with distant metastases were regarded as palliative. Oligometastasis (OM) refers to patients with a limited number of distant metastatic deposits. Treatment of patients with OMs has been reported in patients with lung, colon, breast, prostate and brain malignancies. Selected patients with oligometastatic HNSCC have a higher probability of durable disease control and cure and these patients should be treated aggressively. Treatment options for patients with HNSCC OMs include single or combinations of the three arms of cancer treatment, that is surgery, radiotherapy and chemotherapy/immunotherapy. To date, there are limited studies reporting the management of OM with head and neck malignancy. This review will give insights into the management of OMs in HNSCC.

The impact of particulate electron paramagnetic resonance oxygen sensors on fluorodeoxyglucose imaging characteristics detected via positron emission tomography

During a first-in-humans clinical trial investigating electron paramagnetic resonance tumor oximetry, a patient injected with the particulate oxygen sensor Printex ink was found to have unexpected fluorodeoxyglucose (FDG) uptake in a dermal nodule via positron emission tomography (PET). This nodule co-localized with the Printex ink injection; biopsy of the area, due to concern for malignancy, revealed findings consistent with ink and an associated inflammatory reaction. Investigations were subsequently performed to assess the impact of oxygen sensors on FDG-PET/CT imaging. A retrospective analysis of three clinical tumor oximetry trials involving two oxygen sensors (charcoal particulates and LiNc-BuO microcrystals) in 22 patients was performed to evaluate FDG imaging characteristics. The impact of clinically used oxygen sensors (carbon black, charcoal particulates, LiNc-BuO microcrystals) on FDG-PET/CT imaging after implantation in rat muscle (n = 12) was investigated. The retrospective review revealed no other patients with FDG avidity associated with particulate sensors. The preclinical investigation found no injected oxygen sensor whose mean standard uptake values differed significantly from sham injections. The risk of a false-positive FDG-PET/CT scan due to oxygen sensors appears low. However, in the right clinical context the potential exists that an associated inflammatory reaction may confound interpretation.

Clinical impact and utility of positron emission tomography on occult lymph node metastasis and survival: radical surgery for stage I lung cancer

OBJECTIVE

The surgical result of early-staged lung cancer is not satisfactory due to unexpected postoperative lymph node metastasis and recurrence. This study aimed to investigate which preoperative factors-including the standard uptake value max (SUV_max) of positron emission tomography-could predict occult lymph node metastasis and survival.

METHODS

We retrospectively analyzed data from 598 patients with clinical stage I lung cancer who underwent surgery, and examined their preoperative clinical characteristics.

RESULTS

A total of 1586 patients had surgery for primary lung cancer between 2006 and 2019; 598 patients with clinical stage I lung cancer were the study inclusion; occult lymph node metastasis was detected in 102 (17.1%). Univariable and multivariable analyses showed that SUV_max ≥ 3 (P < 0.001), clinical invasive tumor size ≥ 2 cm (P = 0.009), and carcinoembryonic antigen > 5 (P = 0.03) were associated with significant risk factors rated (%) for occult lymph node metastasis, as follows: high-risk group (three factors), moderate-risk group (two factors) and low-risk group (one factor or none) corresponding to 32.2 (28/87), 22.8 (41/180) and 7.3 (19/262), respectively (P < 0.001). The 5-year overall survival rates (%) of patients without lymph node metastasis holding SUV_max 6 or over were as poor as those of patients with lymph node metastasis (72.0% vs 64.1%; P = 0.56).

CONCLUSIONS

We might consider wedge resection or segmentectomy, omitting lymphadenectomy, for the low-risk group; adjuvant therapy is indicated for patients without lymph node metastasis having SUV_max 6 or over.

Diagnostic values of F-18 FDG PET or PET/CT, CT, and US for Preoperative Lymph Node Staging in Thyroid Cancer: A Network Meta-Analysis

OBJECTIVE

This study compared the diagnostic performance of three different imaging modalities for preoperative lymph node (LN) staging in thyroid cancer patients, using a network meta-analysis (NMA).

METHODS

PubMed and Embase were searched to identify studies evaluating the performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET or PET/CT), computed tomography (CT), and ultrasonography (US) for preoperative LN staging in thyroid cancer patients. The NMA included both patient- and lesion-based analyses. The surface under the cumulative ranking curve (SUCRA) values was used to decide on the most effective diagnostic method.

RESULTS

A total of 3,571 patients from 19 direct comparison studies using three different imaging modalities for preoperative LN staging in thyroid cancer patients were included. US showed the highest SUCRA values for positive predictive values (PPV), negative predictive values (NPV), and accuracy in detection of all cervical LN metastasis. F-18 FDG PET or PET/CT and US showed the highest SUCRA values for PPV and sensitivity, respectively, for central LN, and the highest SUCRA value of specificity and sensitivity, respectively, for lateral LN.

CONCLUSION

The results from this NMA indicate that F-18 FDG PET or PET/CT, CT, and US have complementary diagnostic roles for preoperative staging in thyroid cancer patients.

ADVANCES IN KNOWLEDGE

Using NMA, we comprehensively compared the different diagnostic values and limitations of F-18 FDG PET or PET/CT, CT, and US for the preoperative LN staging in thyroid cancer patients.

Novel system in vitro of classifying oral carcinogenesis based on feature extraction for gray-level co-occurrence matrix using scanned laser pico projector

Oral cancer is among the top 10 causes of death due to cancer worldwide. The prognosis for oral cancer patients is not good, with a 5-year survival rate of only 50%. Earlier and more precise classification will help clinicians make a diagnosis and patients survive. With the advancement of technology, computer-aided detection methods are used to help clinicians form therapy strategies. Gray-level co-occurrence matrix (GLCM) feature extraction of images describing the spatial distribution of gray levels is widely used in medical imaging analysis. Scanned laser pico projector (SLPP) has advantages such as high intensity, directivity, coherence, and mono-color with low bandwidth. In this study, GLCM feature extraction and SLPP reflex images were combined to make a small, non-staining, noninvasive classification system. According to the various image characteristics in oral carcinogenesis, SLPP reflex images better define the borders and three-dimensional structures and provide effective GLCM features such as contrast, energy, and homogeneity to classify carcinogenesis in dysplastic oral keratinocyte (DOK) and normal oral keratinocyte (NOK) cells. Moreover, it also reliably classifies highly metastatic (HSC-3) and tongue cancer (CAL-27) cells. A promising computer-aided classification system for oral cancer was developed to build a reliable intraoral examination system for in situ computer-aided diagnosis in normal clinics.

PET-CT scan-based maximum standardized uptake value as a prognostic predictor in oropharynx squamous cell cancer

INTRODUCTION

Positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-D-glucose integrated with computed tomography (18F-FDG PET-CT) is clinically useful and extensively used in initial staging and follow-up of patients with head and neck squamous cell carcinoma (HNSCC). We studied the potential prognostic significance of primary tumor maximum standard uptake value (SUVmax) by 18F-FDG PET-CT in oropharyngeal cancer.

METHODS

Sixty patients with early and locally advanced histopathologically proven oropharyngeal squamous cell cancer were staged using FDG PET-CT at diagnosis. All patient received radiation therapy and concurrent chemotherapy (in stage III and IVA disease) and were assessed prospectively for treatment outcome. Groups were created based on stage and cut off for SUVmax. The association of SUVmax of primary tumour and stage with disease-free survival and overall survival was analyzed by univariate and multivariate statistics.

RESULTS

In univariate analysis, a primary tumour SUVmax of greater than 13.0 and advanced stage (IVA) predicted inferior disease-free survival (P=0.0241 and 0.0005, respectively) and overall survival (P=0.0510, toward significance and 0.0003, respectively). In proportional hazards analysis, stage was significant only when adjusted for primary SUVmax.

CONCLUSION

SUVmax failed to demonstrate predictive significance in oropharyngeal cancer, and an increase in primary tumor uptake is possibly a direct effect of advanced disease and consequently increased metabolic activity and aggressiveness.

Hybrid positron emission tomography imaging for initial staging of sinonasal tumors: Total lesion glycolysis as prognosticator of treatment response

BACKGROUND

To assess hybrid positron emission tomography (PET) imaging in the initial staging and outcome prediction of sinonasal malignancies.

METHODS

Retrospective study on patients with sinonasal malignancies undergoing hybrid PET imaging for initial staging.

RESULTS

Complete remission (CR) was achieved in 45 of 65 patients (69.2%). Overall sensitivity for detection of primaries using 18F-fluoro-deoxy-d-glucose PET (FDG-PET) was 95.4%, for lymph node metastases 100% and distant metastases (DM) 100%. On univariate analysis, PET parameter total lesion glycolysis (TLG) was associated with achieving CR after primary treatment (176.8 ± 157.2 vs 83.7 ± 110.8, P = .03). Multivariate logistic regression demonstrated that TLG adjusted for the T classification best predicted achievement of CR.

CONCLUSIONS

Hybrid PET imaging yields an excellent sensitivity in detecting primary tumors, lymph node metastases and DM in sinonasal malignancies. TLG of the primary tumor is an independent prognostic factor for achieving CR after initial treatment.

18F-FDG-PET/CT in laryngeal cancer: comparison with conventional imaging and prognostic role

OBJECTIVE

The aim of this study was to investigate the diagnostic accuracy of staging 18 F-FDG-PET/CT in laryngeal cancer, compare these results with conventional imaging (CI) and assess the value of 18 F-FDG-PET/CT features to predict survival.

METHODS

Fifty-four patients with laryngeal squamous cell cancer and baseline 18 F-FDG-PET/CT were retrospectively enrolled. The PET images were analyzed visually and semi-quantitatively by measuring several metabolic parameters. A combination of clinical follow-up/imaging follow-up and/or histopathology was taken as reference standard. Progression free survival (PFS) and disease specific survival (DSS) were computed using Kaplan-Meier curves.

RESULTS

All primary tumors were clearly identified by CI, and 52/54 by 18 F-FDG-PET/CT with a sensitivity of 96.3%. Cervical nodal metastases were detected in 40/54 patients at 18 F-FDG-PET/CT and in 34/49 patients at CI. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy on a patient-based analysis for nodal disease were 100%, 85.7%, 94.6%, 100% and 95.9% at 18 F-FDG-PET/CT, and 91.4%, 85.7%, 94.1%, 80%, 89.8% at CI. Diagnostic performances of PET/CT and CI were not significantly different on a patient-based, side-by-side and level-by-level analysis. 18 F-FDG-PET/CT recognized distant metastases in 7 patients allowing to an upstaging. At a median follow-up of 27 months, relapse/progression of disease occurred in 31 patients and death occurred in 32. Metabolic tumor volume (MTV T), MTV total and total lesion glycolysis (TLG) showed to be independent prognostic factors for PFS.

CONCLUSIONS

Both CI and PET/CT had good diagnostic performances for the staging of laryngeal cancer; baseline metabolic features (MTV and TLG) showed an important prognostic value in assessing the rate of PFS.

Imaging for Target Delineation in Head and Neck Cancer Radiotherapy

The definition of tumor involved volumes in patients with head and neck cancer poses great challenges with the increasing use of highly conformal radiotherapy techniques eg, volumetric modulated arc therapy and intensity modulated proton therapy. The risk of underdosing the tumor might increase unless great care is taken in the process. The information gained from imaging is increasing with both PET and MRI becoming readily available for the definition of targets. The information gained from these techniques is indeed multidimensional as one often acquire data on eg, metabolism, diffusion, and hypoxia together with anatomical and structural information. Nevertheless, much work remains to fully exploit the available information on a patient-specific level. Multimodality target definition in radiotherapy is a chain of processes that must be individually scrutinized, optimized and quality assured. Any uncertainties or errors in image acquisition, reconstruction, interpretation, and delineation are systematic errors and hence will potentially have a detrimental effect on the entire radiotherapy treatment and hence; the chance of cure or the risk of unnecessary side effects. Common guidelines and procedures create a common minimum standard and ground for evaluation and development. In Denmark, the treatment of head and neck cancer is organized within the multidisciplinary Danish Head and Neck Cancer Group (DAHANCA). The radiotherapy quality assurance group of DAHANCA organized a workshop in January 2020 with participants from oncology, radiology, and nuclear medicine from all centers in Denmark, treating patients with head and neck cancer. The participants agreed on a national guideline on imaging for target delineation in head and neck cancer radiotherapy, which has been approved by the DAHANCA group. The guidelines are available in the Supplementary. The use of multimodality imaging is being recommended for the planning of all radical treatments with a macroscopic tumor. 2-[¹⁸F]FDG-PET/CT should be available, preferable in the treatment position. The recommended MRI sequences are T1, T2 with and without fat suppression, and T1 with contrast enhancement, preferable in the treatment position. The interpretation of clinical information, including thorough physical examination as well as imaging, should be done in a multidisciplinary setting with an oncologist, radiologist, and nuclear medicine specialist.

Early 18F-FDG-PET Response During Radiation Therapy for HPV-Related Oropharyngeal Cancer May Predict Disease Recurrence

PURPOSE

Early indication of treatment outcome may guide therapeutic de-escalation strategies in patients with human papillomavirus (HPV)-related oropharyngeal cancer (OPC). This study investigated the relationships between tumor volume and ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) parameters before and during definitive radiation therapy with treatment outcomes.

METHODS AND MATERIALS

Patients undergoing definitive (chemo)radiation for HPV-related/p16-positive OPC were prospectively enrolled on an institutional review board-approved study. ¹⁸F-fluorodeoxyglucose PET/computed tomography scans were performed at simulation and after 2 weeks at a dose of ∼20 Gy. Tumor volume and standardized uptake value (SUV) characteristics were measured. SUV was normalized to blood pool uptake. Tumor volume and PET parameters associated with recurrence were identified through recursive partitioning (RPART). Recurrence-free survival (RFS) and overall survival (OS) curves between RPART-identified cohorts were estimated using the Kaplan-Meier method, and Cox models were used to estimate the hazard ratios (HRs).

RESULTS

From 2012 to 2016, 62 patients with HPV-related OPC were enrolled. Median follow-up was 4.4 years. RPART identified patients with intratreatment SUV_max (normalized to blood pool SUV_mean) <6.7 or SUV_max (normalized to blood pool SUV_mean) ≥6.7 with intratreatment SUV_40% ≥2.75 as less likely to recur. For identified subgroups, results of Cox models showed unadjusted HRs for RFS and OS (more likely to recur vs less likely) of 7.33 (90% confidence interval [CI], 2.97-18.12) and 6.09 (90% CI, 2.22-16.71), respectively, and adjusted HRs of 6.57 (90% CI, 2.53-17.05) and 5.61 (90% CI, 1.90-16.54) for RFS and OS, respectively.

CONCLUSIONS

PET parameters after 2 weeks of definitive radiation therapy for HPV-related OPC are associated with RFS and OS, thus potentially informing an adaptive treatment approach.