Post-treatment imaging appearances in head and neck cancer patients

Skull base osteoradionecrosis: from pathogenesis to treatment

PURPOSE OF REVIEW

This review aims to provide a comprehensive analysis of skull base osteoradionecrosis (ORN), a severe and rare complication of radiotherapy for head and neck malignancies. It explores pathogenesis, clinical presentation, diagnostic strategies, and management approaches, emphasizing the importance of multidisciplinary care in addressing this challenging condition.

RECENT FINDINGS

Skull base ORN results from radiotherapy-induced tissue damage, characterized by hypovascularity, hypoxia, and necrosis, often compounded by secondary infections. Advances in radiotherapy techniques, such as intensity-modulated radiotherapy and heavy particles, have reduced ORN incidence, though cases persist, particularly in high-dose radiotherapy fields. Emerging treatments, including hyperbaric oxygen therapy and the pentoxifylline-tocopherol protocol, show promise but lack robust evidence for standardized use. Surgical interventions, especially those incorporating vascularized tissue reconstruction, have demonstrated favorable outcomes in refractory cases. Recent studies underscore the utility of multimodal imaging techniques, including MRI and PET/CT, for distinguishing ORN from tumor recurrence.

SUMMARY

Skull base ORN represents a complex and potentially life-threatening condition requiring tailored, multidisciplinary management. Although advancements in diagnostics and therapeutics have improved outcomes, significant challenges remain, particularly in developing standardized protocols. Further research is needed to refine treatment strategies and improve evidence-based practices for this entity.

Positron Emission Tomography-Magnetic Resonance Imaging, a New Hybrid Imaging Modality for Dentomaxillofacial Malignancies-A Systematic Review

Background/Objectives: Emerging hybrid imaging modalities, like Positron Emission Tomography/Computed Tomography (PET/CT) and Positron Emission Tomography/Magnetic Resonance Imaging (PET/MRI), are useful for assessing head and neck cancer (HNC) and its prognosis during follow-up. PET/MRI systems enable simultaneous PET and MRI scans within a single session. These combined PET/MRI scanners merge MRI's better soft tissue contrast and the molecular metabolic information offered by PET. Aim: To review scientific articles on the use of hybrid PET/MRI techniques in diagnosing dentomaxillofacial malignancies. Method: The available literature on the use of PET/MRI for the diagnosis of dentomaxillofacial malignancies in four online databases (Scopus, PubMed, Web of Science, and the Cochrane Library) was searched. Eligible for this review were original full-text articles on PET/MRI imaging, published between January 2010 and November 2024, based on experimental or clinical research involving humans. Results: Out of the 783 articles retrieved, only twelve articles were included in this systematic review. Nearly half of the articles (5 out of 12) concluded that PET/MRI is superior to PET, MRI, and PET/CT imaging in relation to defining malignancies' size. Six articles found no statistically significant results and the diagnostic accuracy presented was similar in PET/MRI versus MRI and PET/CT images. Regarding the overall risk of bias, most articles had a moderate risk. Conclusions: The use of PET/MRI in HNC cases provides a more accurate diagnosis regarding dimensions of the tumor and thus a more accurate surgical approach if needed. Further prospective studies on a larger cohort of patients are required to obtain more accurate results on the application of hybrid PET/MRI.

Radiologic findings of occult nodal metastasis during clinically-N0 salvage total laryngectomy

INTRODUCTION

Occult nodal disease (OND) during clinically-N0 salvage total laryngectomy (TL) can be detected with the Neck-Imaging-Reporting-and-Data-Systems (NI-RADS). However, some patients will still have OND revealed on final pathology.

METHODS

A retrospective study on all patients who had OND during salvage TL with elective neck dissection (END) between 2009 and 2021 was performed. Repeat CT and PET scan interpretation was performed to evaluate their preoperative imaging for suspicious features.

RESULTS

Among 81 salvage TL patients undergoing END, 12 (16%) had OND and a total of 26 occult nodes were identified. On pathology, the average node length [SD] was 0.6 cm [0.3]. On CT, 31% (8 of 26) had rounded morphology. On PET, most had SUVmax below blood pool. One patient scored NI-RADS 2; the rest scored 1.

CONCLUSIONS

On re-review of preoperative imaging, occult nodes were subtle and challenging to identify. Despite no clear impact on survival, performing an END may provide prognostic information.

Differentiation of submandibular sialadenitis based on apparent diffusion coefficient

OBJECTIVES

This study aimed to quantify the submandibular gland in suppurative sialadenitis, primary Sjögren's syndrome (pSS) and radiation-induced sialadenitis using the apparent diffusion coefficient (ADC) for differential diagnosis.

SUBJECTS AND METHODS

This retrospective study included 16 patients with suppurative sialadenitis (n = 9), pSS (n = 3) and radiation-induced sialadenitis (n = 4) who underwent magnetic resonance imaging between June 2006 and May 2022. The ADC of the submandibular glands in each state was calculated, and the differences were analysed using a one-way analysis of variance and Tukey's post hoc test. Receiver operating characteristic curves were used to assess the ability of the ADC to distinguish each condition. Statistical significance was set at p < 0.05.

RESULTS

The mean ADC value (×10-3 mm2/s) ± standard deviation in the control (non-affected side of the suppurative sialadenitis group), suppurative sialadenitis, pSS and radiation-induced groups were 0.94 ± 0.16, 1.24 ± 0.16, 1.33 ± 0.13 and 1.5 ± 0.12, respectively (p < 0.001). The diagnostic value for distinguishing each group was ≥0.75.

CONCLUSION

ADC values are useful for quantitatively assessing and distinguishing submandibular glands in suppurative sialadenitis, primary Sjögren's syndrome and radiation-induced sialadenitis.

Diagnostic Accuracy of [18F]FDG PET/MRI in Head and Neck Squamous Cell Carcinoma: A Systematic Review and Metaanalysis

This study evaluates the diagnostic utility of PET/MRI for primary, locoregional, and nodal head and neck squamous cell carcinoma (HNSCC) through systematic review and metaanalysis. Methods: A systematic search was conducted using PubMed and Scopus to identify studies on the diagnostic accuracy of PET/MRI for HNSCC. The search included specific terms and excluded nonhybrid PET/MRI studies, and those with a sample size of fewer than 10 patients were excluded. Results: In total, 15 studies encompassing 638 patients were found addressing the diagnostic test accuracy for PET/MRI within the chosen subject domain. Squamous cell carcinoma of the nasopharynx was the most observed HNSCC subtype (n = 198). The metaanalysis included 12 studies, with pooled sensitivity and specificity values of 93% and 95% per patient for primary disease evaluation, 93% and 96% for locoregional evaluation, and 89% and 98% per lesion for nodal disease detection, respectively. An examination of a subset of studies comparing PET/MRI against PET/CT or MRI alone for evaluating nodal and locoregional HNSCC found that PET/MRI may offer slightly higher accuracy than other modalities. However, this difference was not statistically significant. Conclusion: PET/MRI has excellent potential for identifying primary, locoregional, and nodal HNSCC.

Reconstructive flap surgery in head and neck cancer patients: an interdisciplinary view of the challenges encountered by radiation oncologists in postoperative radiotherapy

Background

Major advances have been made in reconstructive surgery in the last decades to reduce morbidity in head and neck cancer. Flaps are now present in 80% of patients with oral cavity cancer to cover anatomic, functional, and cosmetic needs. However, gaps in interdisciplinary innovation transfer from surgery to postoperative radiotherapy (poRT) remain challenging. We aimed to provide an interdisciplinary view of the challenges encountered by radiation oncologists in planning head and neck postoperative radiotherapy.

Methods

A systematic and critical review was conducted to address areas of optimization in surgery and radiology that may be relevant to poRT.

Results

Despite extensive surgical literature on flap techniques and salvage surgery, 13 retrospective series were identified, where flap outcomes were indirectly compared between surgery alone or poRT. These low-evidence studies suggest that radiotherapy accelerates flap atrophy, fibrosis, and osteoradionecrosis and deteriorates functional outcomes. Preliminary evidence suggests that tumor spread occurs at the flap-tissue junction rather than in the flaps. One prospective 15-patient study showed 31.3% vs. 39.2% flap volume reduction without or with poRT. In an international consensus, experts recognized the needs for optimized flap-sparing poRT against flap-related functional deterioration and bone damage. CT, MRI, and PET-CT modalities show potential for the delineation of the junction area between native tissues and flap for flap segmentation and to characterize flap-specific changes quantitatively and correlate them with patterns of relapse or complications.

Conclusion

Flap management in poRT is insufficiently documented, but poRT seems to damage flaps. Current gaps in knowledge underscore the need for prospective flap assessment and interdisciplinary trials investigating flap morbidity minimization by flap-sparing poRT planning.

Radiomic Assessment of Radiation-Induced Alterations of Skeletal Muscle Composition in Head and Neck Squamous Cell Carcinoma within the Currently Clinically Defined Optimal Time Window for Salvage Surgery-A Pilot Study

Patients with locally advanced head and neck squamous cell carcinoma (HNSCC) frequently require primary radiochemotherapy (RCT). Despite intensity modulation, the desired radiation-induced effects observed in HNSCC may also be observed as side effects in healthy tissue, e.g., the sternocleidomastoid muscle (SCM). These side effects (e.g., tissue fibrosis) depend on the interval between the completion of RCT and restaging CT. For salvage surgery, the optimal time window for surgery is currently clinically postulated at between 6 and 12 weeks after completion of RCT. Thus, no extensive tissue fibrosis is to be expected. This interval is based on clinical studies exploring surgical complications. Studies directly exploring radiation-induced changes of the SCM in HNSCC patients are sparse. The present study quantified tissue alterations in the SCM and paravertebral musculature (PVM) after RCT, applying radiomics to determine the optimal time window for salvage surgery. Three radiomic key parameters, (1) volume, (2) mean positivity of pixels (MPP), and (3) uniformity, were extracted with mint LesionTM in the staging CTs and restaging CTs of 98 HNSCC patients. Of these, 25 were female, the mean age was 62 (±9.6) years, and 80.9% were UICC Stage IV. The mean restaging interval was 55 (±28; range 29-229) days. Only the mean volume significantly decreased after RCT, from 9.0 to 8.4 and 96.5 to 91.9 mL for the SCM and PVM, respectively (both p = 0.007, both Cohen's d = 0.28). In addition, the mean body mass index (BMI) decreased from 23.9 (±4.2) to 21.0 (±3.6) kg/m² (p < 0.001; Cohen's d = 0.9). The mean BMI decreased significantly and was correlated with the volume decrease for the SCM (r = 0.27; p = 0.007) and PVM (r = 0.41; p < 0.001). If t-test p-values were adjusted for the BMI decrease, no significant change in volumes for the SCM and PVM was observed (both p > 0.05). The present data support the clinically postulated optimal interval for salvage surgery of 6 to 12 weeks.

Imaging Recommendations for Diagnosis, Staging, and Management of Nasopharynx Carcinoma

Nasopharyngeal carcinoma (NPC) is an epithelial carcinoma originating from lining of the nasopharyngeal mucosa usually at the fossa of Rosenmuller (pharyngeal recess). An early detection on endoscopy can be rewarding, however, often difficult as the tumor at the pharyngeal recess is hidden from the endoscopic view. Magnetic resonance imaging and positron emission tomography–computed tomography form the backbone of detection and spread of the carcinoma into local and distant regions. These modalities help further characterize the precise locoregional infiltration and lymph nodal involvement which aids in the planning of the surgery/chemoradiotherapy. They also help in the follow-up evaluation and further management strategies. Many research and treatment groups namely American Joint Committee on Cancer, National Comprehensive Cancer Network, American Society of Clinical Oncology, American College of Radiology, Radiological Society of North America, European Society of Radiology (iGuide), Indian Radiological & Imaging Association/Indian College of Radiology and Imaging, National Cancer Grid, etc. have devised guidelines for the optimal assessment and treatment of NPC. The present document aims at providing a comprehensive review of the clinicoradiological recommendations for the diagnosis and management of NPC based on these guidelines as well as personalized experience of the contributors.

Common blind spots and interpretive errors of neck imaging

Complex anatomy and a wide spectrum of diseases in the head and neck predispose interpretation of neck imaging to cognitive pitfalls and perceptual errors. Extra attention to common blind spots in the neck and familiarity with common interpretive challenges could aid radiologists in preventing these diagnostic errors.

Postoperative Imaging Appearance of Iliac Crest Free Flaps Used for Palatomaxillary Reconstructions

The osteomyocutaneous iliac crest free flap is a reconstructive option for segmental mandibular or complex palatomaxillary defects. Familiarity with the radiographic appearance of free flaps such as the iliac crest is necessary for the postoperative evaluation of patients after mandibular, maxillary, or palatal reconstructions because it allows radiologists to properly monitor and interpret the appearance of the flap over time. This study presents a retrospective review of 5 patients who underwent palatomaxillary reconstruction with an iliac crest free flap at our institution. The imaging appearances of the 5 patients were analyzed to determine the key radiographic characteristics of a healthy and successful iliac crest free flap. Radiographic fluency with the imaging appearance of the iliac crest free flap, as well as the new anatomy of the region in the postoperative period, will allow for better interpretation of the flap appearance on imaging and will prevent false identification of tumor recurrence.

Radiation Induced Mucositis: What the Radiologist Needs to Know

Radiation induced oral mucositis (RIOM) is a common and debilitating complication of radiation therapy for head and neck cancers. RIOM can lead to oral pain, dysphagia, and reduced oral intake, which can be severe enough to necessitate placement of a feeding tube or utilization of total parenteral nutrition. When severe, RIOM can cause premature termination of radiation therapy and can alter treatment plans leading to suboptimal treatment doses. While patient reporting of RIOM symptoms has been the gold standard of documenting RIOM progression, little has been described in the radiology literature concerning the typical imaging findings of RIOM. Herein, we review the pathophysiology and clinical presentation that underlies the development of RIOM with illustrative cases to highlight the relevant imaging findings related to RIOM for the practicing radiologist.

Imaging of the post-treatment neck

Post-treatment imaging of the neck is complex. It is important to have an understanding of the expected treatment related appearances as well as the possible complications. Common findings after radiation therapy include generalised soft-tissue oedema and thickening of the skin and platysma muscle. There are a number of complications of radiation that may be seen on imaging, including osteoradionecrosis, chondronecrosis, and accelerated atherosclerosis. Surgical procedures are variable depending on the primary tumour site and extent. The use of flap reconstructions can further complicate the imaging appearances. Any new nodule of enhancement or bone/cartilage erosion should raise concern for tumour recurrence. It is also important to assess for nodal recurrence. A standardised approach to reporting may help to increase accuracy and guide treatment decisions.

Osteoradionecrosis of the skull base

Radiation therapy (RT) is often necessary for the treatment of head and neck cancers. Osteoradionecrosis (ORN) is a rare, but potentially serious complication of RT. RT leads to the destruction of vasculature in radiated tissue causing hypoxia and tissue necrosis. ORN can occur in any bone, but bones with naturally poor blood supply appear to be more susceptible. Bones of the skull base are susceptible, with ORN occurring in the anterior, central, and lateral skull base. Risk factors include cancer type and location, radiation dose, and a variety of patient factors. Patients often present with pain, bleeding, and foul odor and are typically found to have exposed and necrotic bone. Treatment options vary depending on the severity, but typically include pentoxifylline and vitamin E as well as surgical debridement, with less evidence supporting hyperbaric oxygen therapy. Recognition and prompt treatment of ORN will allow for improved patient outcomes.

Extra-nodal extension in head and neck cancer: how radiologists can help staging and treatment planning

Extranodal extension (ENE) is a significant prognostic factor in p16-negative head and neck squamous-cell carcinoma and is classified as N3b by the American Joint Committee on Cancer 8th edition. While most previous radiological studies have focused on the diagnostic performance of pathological ENE, radiologists should be able to provide more clinically relevant information on this entity. The purpose of this article is to review the clinical implications of ENE, to describe key imaging features of ENE with clinical and histopathological correlations and to discuss evaluation of ENE for clinical staging, treatment planning, and predicting the response to treatment. First, we discuss the basics of ENE, including definitions of pathological and clinical ENE and its association with imaging findings. Second, we describe the ENE extension pattern at each location according to level system. The crucial structures determining the choice of treatment include the deep fascia in the deep cervical layer, internal and common carotid arteries, and mediastinal structures. Invasion of the muscles, internal jugular vein, nerves, or mandible also affect the surgical procedure. Finally, we discuss assessment of nodal metastasis after chemoradiotherapy.

Imaging of Surgical Free Flaps in Head and Neck Reconstruction

Head and neck surgical reconstruction is complex, and postoperative imaging interpretation is challenging. Surgeons now use microvascular free tissue transfer, also known as free flaps, more frequently in head and neck reconstruction than ever before. Thus, an understanding of free flaps, their expected appearance on cross-sectional imaging, and their associated complications (including tumor recurrence) is crucial for the interpreting radiologist. Despite the complexity and increasing frequency of free flap reconstruction, there is no comprehensive head and neck resource intended for the radiologist. We hope that this image-rich review will fill that void and serve as a go to reference for radiologists interpreting imaging of surgical free flaps in head and neck reconstruction.

Essentials on Oncological Imaging: Postoperative Computed Tomography and Magnetic Resonance Imaging of Oral Tongue Cancer

The contribution of diagnostic imaging in evaluating the pre- and postoperative status of tongue cancer is essential. Interpretation of postoperative images is made difficult by deformation; therefore, it is necessary to know how surgical technique, biological reaction, postoperative anatomy, and local recurrence are reflected on the images. This study explains the postoperative imaging features of tongue cancer to help in the early detection of local recurrence and avoid inappropriate treatment. We review schematic drawings of representative surgical procedures for tongue carcinoma, variable radiological features in postoperative conditions with or without complications, and typical features of local failures and their mimics. This article clarifies the important tasks of radiologists and clinicians in the postoperative evaluation of tongue carcinoma.

Imaging Evaluation of the Head and Neck Oncology Patient

Imaging plays a multifaceted role in the diagnosis and characterization of head and neck oncological patients and is integral to their care. Given the complexity of treatment, a multimodality approach is often necessary. With the advent of new technologies, imaging can also be used to predict tumor behavior and treatment response. In this chapter, with selected case examples, we describe the various imaging modalities available and offer suggestions on their utilization.

Tumor regression patterns by follow-up duration in patients with nasopharyngeal carcinoma treated with concurrent chemoradiotherapy

The aim of this study was to describe the patterns of tumor regression with respect to follow-up duration after chemoradiotherapy in patients with nasopharyngeal carcinoma. A total of 27 patients with nasopharyngeal carcinoma were included and received definitive concurrent chemoradiotherapy. Patterns of primary tumor regression and development of locoregional recurrences were evaluated by imaging studies every 1 to 2 months. Primary tumors gradually regressed over the period of follow-up. The median time to full regression was 4.9 months (range, 1.5-19.4). In 61.5% of patients, the primary tumor continued to regress for >4 months after completion of chemoradiotherapy. Six patients experienced locoregional recurrence during follow-up, all of which occurred after full regression of the primary tumor. A patient group with delayed regression did not have poorer prognosis than a patient group with early regression. Older age, non-current-smoker status, advanced T stage, and higher daily radiation dose were significantly associated with delayed primary tumor regression. Nasopharyngeal carcinoma continued to regress for >4 months after chemoradiotherapy in a considerable number of patients. We recommend waiting for >4 months for full regression of nasopharyngeal carcinomas after chemoradiotherapy, if signs of persistent or recurrent disease are not evident on follow-up examination.

High b-Value Diffusion MRI to Differentiate Recurrent Tumors from Posttreatment Changes in Head and Neck Squamous Cell Carcinoma: A Single Center Prospective Study

Recently DW-MR Imaging has shown promising results in distinguishing between recurrent tumors and posttreatment changes in Head and Neck Squamous Cell Carcinoma (HNSSC). Aim of this study was to evaluate the diagnostic performances of DWI at high b-value (b = 2000 s/mm²) compared to standard b-value (b = 1000 s/mm²) and ADC_ratio values (ADC_ratio = ADC₂₀₀₀/ADC₁₀₀₀ × 100) to differentiate recurrent tumors from posttreatment changes after treatment of HSNCC. 20 patients (16 M, 4 F) underwent MR Imaging between 2 and 16 months (mean 7) after treatment. Besides morphological sequences, we performed single-shot echo-planar DWI at b = 1000 s/mm² and b = 2000 s/mm², and corresponding ADC maps were generated (ADC₁₀₀₀ and ADC₂₀₀₀, resp.). By considering contrast-enhanced T1-weighted images as references, ROIs were drawn in order to evaluate mean ADC₁₀₀₀, ADC₂₀₀₀, and ADC_ratio. The mean ADC₁₀₀₀ and ADC₂₀₀₀ in recurrent tumors were significantly lower than those in posttreatment changes (P = 0.001 and P = 0.016, resp.). Moreover, the mean ADC_ratio between the two groups showed a statistically significant difference (P = 0.002). Sensitivity, specificity, and accuracy of ADC_ratio were 82.0%, 100%, and 90%, respectively, by considering an optimal cutoff value of 65.5%. ADC_ratio is a promising value to differentiate between recurrent tumors and posttreatment changes in HNSCC and may be more useful than ADC₁₀₀₀ and ADC₂₀₀₀.

Diagnostic Performance of Whole-Body PET/MRI for Detecting Malignancies in Cancer Patients: A Meta-Analysis

Background

As an evolving imaging modality, PET/MRI is preliminarily applied in clinical practice. The aim of this study was to assess the diagnostic performance of PET/MRI for tumor staging in patients with various types of cancer.

Methods

Relevant articles about PET/MRI for cancer staging were systematically searched in PubMed, EMBASE, EBSCO and the Cochrane Library. Two researchers independently selected studies, extracted data and assessed the methodological quality using the QUADAS tool. The pooled sensitivity, specificity, diagnostic odds ratio (DOR), positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were calculated per patient and per lesion. The summary receiver-operating characteristic (SROC) curves were also constructed, and the area under the curve (AUC) and Q* estimates were obtained.

Results

A total of 38 studies that involved 753 patients and 4234 lesions met the inclusion criteria. On a per-patient level, the pooled sensitivity and specificity with 95% confidence intervals (CIs) were 0.93 (0.90–0.95) and 0.92 (0.89–0.95), respectively. On a per-lesion level, the corresponding estimates were 0.90 (0.88–0.92) and 0.95 (0.94–0.96), respectively. The pooled PLR, NLR and DOR estimates were 6.67 (4.83–9.19), 0.12 (0.07–0.21) and 75.08 (42.10–133.91) per patient and 10.91 (6.79–17.54), 0.13 (0.08–0.19) and 102.53 (59.74–175.97) per lesion, respectively.

Conclusion

According to our results, PET/MRI has excellent diagnostic potential for the overall detection of malignancies in cancer patients. Large, multicenter and prospective studies with standard scanning protocols are required to evaluate the diagnostic value of PET/MRI for individual cancer types.

Postoperative Imaging and Surveillance in Large Nerve Perineural Spread

We present a review of the imaging surveillance following treatment for large nerve perineural spread in the skull base. The expected appearance and possible complications following surgery and radiotherapy are discussed. Imaging examples of the possible sites of disease recurrence are also presented.

Tumor Regression Patterns Based on Follow-up Duration in Patients With Head and Neck Squamous Cell Carcinoma Treated With Radiotherapy or Chemoradiotherapy

Objectives

We describe patterns of tumor regression based on follow-up duration after radiotherapy (RT) or chemo-RT in patients with head and neck squamous cell carcinoma.

Methods

Thirty-one patients with head and neck squamous cell carcinoma were included in this study and received definitive RT or chemo-RT. The pattern of primary tumor regression after treatment was evaluated every 1 to 2 months. Predictive factors for the length of time to full regression were also analyzed.

Results

Among all patients, 27 patients showed regression of the primary tumor, 24 patients showed >50% regression, and 15 patients showed total regression. The primary tumor gradually regressed during the course of follow-up. The median time to full regression was 5.2 months (range, 1.3 to 17.9 months). In the 24 patients who showed >50% regression, the rate of >50% regression increased over time as follows: 25.0% at 1 month, 62.5% at 2 months, 75.0% at 3 months, 91.7% at 4 months, and 95.8% at 5 months. Higher total RT dose and shorter RT duration were associated with longer time to full regression.

Conclusion

A substantial number of patients showed continuous regression of the primary tumor for more than 2 months after treatment. The timing for evaluation of tumor regression must be greater than 2 months from the completion of RT or chemo-RT in patients with head and neck squamous cell carcinoma.

Diagnostic value of retrospective PET-MRI fusion in head-and-neck cancer

Background

To assess the diagnostic value of retrospective PET-MRI fusion and to compare the results with side-by-side analysis and single modality use of PET and of MRI alone for locoregional tumour and nodal staging of head-and-neck cancer.

Methods

Thirty-three patients with head-and-neck cancer underwent preoperative contrast-enhanced MRI and PET/CT for staging. The diagnostic data of MRI, PET, side-by-side analysis of MRI and PET images and retrospective PET-MRI fusion were systematically analysed for tumour and lymph node staging using receiver operating characteristic (ROC) analysis. The results were correlated to the histopathological evaluation.

Results

The overall sensitivity/specificity for tumour staging for MRI, PET, side-by-side analysis and retrospective PET-MRI fusion was 79%/66%, 82%/100%, 86%/100% and 89%/100%, respectively. The overall sensitivity/specificity for nodal staging on a patient basis for MRI, PET, side-by-side analysis and PET-MRI fusion was 94%/64%, 94%/91%, 94%/82% and 94%/82%, respectively. MRI, PET, side-by-side analysis and retrospective image fusion were associated with correct diagnosis/over-staging/under-staging of N-staging in 70.4%/18.5%/11.1%, 81.5%/7.4%/11.1%, 81.5%/11.1%/7.4% and 81.5%/11.1%/7.4%, respectively.

ROC analysis showed no significant differences in tumor detection between the investigated methods. The Area Under the Curve (AUC) for MRI, PET, side-by-side analysis and retrospective PET-MRI fusion were 0.667/0.667/0.702/0.708 (p > 0.05). The most reliable technique in detection of cervical lymph node metastases was PET imaging (AUC: 0.95), followed by side-by-side analysis and retrospective image fusion technique (AUC: 0.941), which however, was not significantly better then the MRI (AUC 0.935; p > 0.05).

Conclusions

We found a beneficial use of multimodal imaging, compared with MRI or PET imaging alone, particular in individual cases of recurrent tumour disease. Side-by-side analysis and retrospective image fusion analysis did not perform significantly differently.

Post-treatment appearances, pitfalls, and patterns of failure in head and neck cancer on FDG PET/CT imaging

Majority of patients with head and neck cancer are treated with combined treatment regimes such as surgery, radiation therapy, and chemotherapy. The loss of structural symmetry and imaging landmarks as a result of therapy makes post-treatment imaging a daunting task on conventional modalities like computed tomography (CT) scan and magnetic resonance imaging (MRI) as well as on 18 Fluorine-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (18F FDG PET/CT). Combined multimodality treatment approach causes various tissue changes that give rise to a spectrum of findings on FDG PET/CT imaging, which are depicted in this atlas along with a few commonly encountered imaging pitfalls. The incremental value of FDG PET/CT in detecting locoregional recurrences in the neck as well as distant failures has also been demonstrated.

PET/MRI and PET/CT in follow-up of head and neck cancer patients

PURPOSE

Positron emission tomography (PET)/MRI combines the functional ability of PET and the high soft tissue contrast of MRI. The aim of this study was to assess contrast-enhanced (ce)PET/MRI compared to cePET/CT in patients with suspected recurrence of head and neck cancer (HNC).

METHODS

Eighty-seven patients underwent sequential cePET/CT and cePET/MRI using a trimodality PET/CT-MRI set-up. Diagnostic accuracy for the detection of recurrent HNC was evaluated using cePET/CT and cePET/MRI. Furthermore, image quality, presence of unclear (18)F-fluorodeoxy-D-glucose (FDG) findings of uncertain significance and the diagnostic advantages of use of gadolinium contrast enhancement were analysed.

RESULTS

cePET/MRI showed no statistically significant difference in diagnostic accuracy compared to cePET/CT (91.5 vs 90.6%). Artefacts' grade was similar in both methods, but their location was different. cePET/CT artefacts were primarily located in the suprahyoid area, while on cePET/MRI, artefacts were more equally distributed among the supra and infrahyoid neck regions. cePET/MRI and cePET/CT showed 34 unclear FDG findings; of those 11 could be solved by cePET/MRI and 5 by cePET/CT. The use of gadolinium in PET/MRI did not yield higher diagnostic accuracy, but helped to better define tumour margins in 6.9% of patients.

CONCLUSION

Our data suggest that cePET/MRI may be superior compared to cePET/CT to specify unclear FDG uptake related to possible tumour recurrence in follow-up of patients after HNC. It seems to be the modality of choice for the evaluation of the oropharynx and the oral cavity because of a higher incidence of artefacts in cePET/CT in this area mainly due to dental implants. However, overall there is no statistically significant difference.

Differentiation of recurrent tumor and posttreatment changes in head and neck squamous cell carcinoma: application of high b-value diffusion-weighted imaging

BACKGROUND AND PURPOSE

High b-value DWI has been expected to have an additional diagnostic role and demonstrated some promising results in head and neck cancer. The aim of this study was to evaluate the diagnostic performance of DWI at a high b-value (b=2000 s/mm(2)) compared with a standard b-value (b=1000 s/mm(2)) and the ratio of ADC values of high and standard b-values for their ability to differentiate between recurrent tumor and posttreatment changes after the treatment of head and neck squamous cell carcinoma.

MATERIALS AND METHODS

A total of 33 patients diagnosed with head and neck squamous cell carcinoma were enrolled in the present study; all had contrast-enhancing lesions on follow-up MR imaging. All patients underwent single-shot echo-planar DWI at b=1000 s/mm(2) and b=2000 s/mm(2), and corresponding ADC maps were generated (ADC1000 and ADC2000, respectively). The mean ADC1000, ADC2000, and ADCratio (ADCratio = ADC2000/ADC1000 × 100) values were evaluated within a manually placed ROI with contrast-enhanced T1-weighted images as references. For the statistical analysis, we performed a Student t test and multivariate logistic regression.

RESULTS

The mean ADC1000 in recurrent tumor was significantly lower than that in posttreatment changes (P < .001), whereas the mean ADC2000 resulted in no significant difference (P = .365). The mean ADCratio was significantly higher in recurrent tumor than that in posttreatment changes (73.5 ± 7.2% vs 56.9 ± 8.8%, respectively; P < .001). Multivariate logistic regression analysis revealed that the ADCratio was the only independently differentiating variable (P = .024). The sensitivity, specificity, and accuracy of ADCratio were 95.0%, 69.2%, and 84.8%, respectively, by use of the optimal cutoff value of 62.6%.

CONCLUSIONS

We suggest that the ADCratio calculated from the ADC1000 and ADC2000 is a promising value for the differentiation of recurrent tumor and posttreatment changes in head and neck squamous cell carcinoma.

Posttreatment CT and MR imaging in head and neck cancer: what the radiologist needs to know

In patients with head and neck cancer, posttreatment imaging can be complicated and difficult to interpret because of the complexity of the surgical procedures performed and the postirradiation changes, but such imaging is critical for the evaluation of (a) the response to therapy and (b) tumor control. Posttreatment changes are affected by the type of surgery performed, reconstruction, neck dissection, and radiation therapy. Three types of flaps are used for reconstruction in the head and neck region: (a) the local flap, with geometric repositioning of adjacent tissue; (b) the pedicle flap, with rotation of donor tissue and preservation of the original vascular system; and (c) the free flap, with transfer of tissue that is revascularized by using microvascular surgical techniques. The posttreatment imaging findings in patients with head and neck cancer can be divided into four groups: altered anatomy secondary to surgical reconstruction, tumor recurrence, potential postsurgical complications, and possible postirradiation changes. Potential postsurgical complications are wound infection, abscess, fistula, flap necrosis, hematoma, chylous fistula, and serous retention. Possible postirradiation changes include mucosal necrosis, osteoradionecrosis, radiation-induced vasculopathy, radiation pneumonitis, radiation lung fibrosis, radiation-induced brain necrosis, and radiation-induced secondary malignancies. A familiarity with the imaging characteristics of posttreatment changes and of the potential complications caused by surgery and irradiation and an ability to differentiate these findings from tumor recurrence are essential for posttreatment surveillance and follow-up management of patients with head and neck cancer.

Radiation necrosis of the pons after radiotherapy for nasopharyngeal carcinoma: diagnosis and treatment

We report a case of radiation necrosis in an unusual location, the pons, in a patient who had received chemoradiation for nasopharyngeal carcinoma (NPC) over one year prior to presentation. This patient presented with subacute onset of ataxic hemiparesis and slurred speech. Initial magnetic resonance imaging (MRI) studies showed two 1-2 cm peripherally contrast-enhancing lesions in the pons with extensive surrounding edema. Proton magnetic resonance spectroscopy (MRS) played a key role in narrowing the differential diagnosis to radiation necrosis. The patient underwent biweekly bevacizumab therapy and has remained clinically stable with radiologic improvement of his lesion. In addition to this case, we present an overview of the use of advanced neuroimaging in distinguishing radiation necrosis of the central nervous system (CNS) from other entities as well as the role of bevacizumab in treatment.