Posttreatment imaging of the nasopharynx

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

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

Evaluation of 11 C-Choline PET/CT for T Staging and Tumor Volume Delineation in Nasopharyngeal Cancer Patients in Comparison to 18 F-FDG PET/CT

PURPOSE

Accurate determination of the primary tumor extension of nasopharyngeal carcinoma (NPC) by 18 F-FDG PET/CT is limited by the high physiological 18 F-FDG uptake in the surrounding area, especially in the brain tissue. We aimed to assess whether 11 C-choline PET/CT could improve the accuracy of T staging and tumor volume delineation for NPC patients.

METHODS

Patients with pathologically confirmed diagnosis of NPC were enrolled. The primary tumor extension of each patient was evaluated by 11 C-choline PET/CT, 18 F-FDG PET/CT, and contrast-enhanced MRI. The PET/CT-based tumor volume ( VPET ) was measured by 3 threshold methods, including the threshold of SUV 2.5 (Th 2.5 ), 40% of maximal SUV (Th 40% ), and the relative background-dependent threshold (Th bgd ). Tumor volume and Dice similarity coefficient were compared among VPET with different segmentation methods and VMR .

RESULTS

Thirty-three patients with treatment-naive NPC and 6 patients with suspicious recurrent disease were enrolled. The NPC lesions were avid for both 11 C-choline and 18 F-FDG. Visual analysis showed that 11 C-choline PET/CT had better contrast and higher discernability than 18 F-FDG PET/CT for intracranial, skull base, and orbital involvement. 11 C-choline PET/CT also exhibited advantage over MRI for differentiation between local recurrence and radiation-induced alterations. For the tumor delineated, the VMR was larger than VPET in general, except for 18 F-FDG PET/CT with Th 2.5 threshold. For all 3 threshold methods applied, 11 C-choline PET/CT produced more consistent and comparable tumor volume to MRI than 18 F-FDG PET/CT. 11 C-choline PET/CT with Th bgd threshold showed the closest tumor volume and highest similarity to MRI.

CONCLUSIONS

11 C-choline PET/CT provides a higher accuracy than 18 F-FDG PET/CT in mapping tumor extension in locally advanced NPC and may be a promising complement to MRI in delineating the primary tumor.

Benefit of [18F] FDG PET/CT in the diagnosis and salvage treatment of recurrent nasopharyngeal carcinoma

PURPOSE

To compare PET/CT, MRI and ultrasonography in detecting recurrence of nasopharyngeal carcinoma and identify their benefit in staging, contouring and overall survival (OS).

METHODS

Cohort A included 1453 patients with or without histopathology-confirmed local recurrence, while cohort B consisted of 316 patients with 606 histopathology-confirmed lymph nodes to compare the sensitivities and specificities of PET/CT, MRI and ultrasonography using McNemar test. Cohorts C and D consisted of 273 patients from cohort A and 267 patients from cohort B, respectively, to compare the distribution of PET/CT-based and MRI-based rT-stage and rN-stage and the accuracy of rN-stage using McNemar test. Cohort E included 30 random patients from cohort A to evaluate the changes in contouring with or without PET/CT by related-samples T test or Wilcoxon rank test. The OS of 61 rT3-4N0M0 patients staged by PET/CT plus MRI (cohort F) and 67 MRI-staged rT3-4N0M0 patients (cohort G) who underwent similar salvage treatment were compared by log-rank test and Cox regression.

RESULTS

PET/CT had similar specificity to MRI but higher sensitivity (93.9% vs. 79.3%, P < 0.001) in detecting local recurrence. PET/CT, MRI and ultrasonography had comparable specificities, but PET/CT had greater sensitivity than MRI (90.9% vs. 67.6%, P < 0.001) and similar sensitivity to ultrasonography in diagnosing lymph nodes. According to PET/CT, more patients were staged rT3-4 (82.8% vs. 68.1%, P < 0.001) or rN + (89.9% vs. 69.3%, P < 0.001), and the rN-stage was more accurate (90.6% vs. 73.8%, P < 0.001). Accordingly, the contours of local recurrence were more precise (median Dice similarity coefficient 0.41 vs. 0.62, P < 0.001) when aided by PET/CT plus MRI. Patients staged by PET/CT plus MRI had a higher 3-year OS than patients staged by MRI alone (85.5% vs. 60.4%, P = 0.006; adjusted HR = 0.34, P = 0.005).

CONCLUSION

PET/CT more accurately detected and staged recurrence of nasopharyngeal carcinoma and accordingly complemented MRI, providing benefit in contouring and OS.

Posttreatment Magnetic Resonance Imaging Surveillance of Head and Neck Cancers

Treatment strategies and recommended surveillance imaging differ for head and neck cancers depending on subsite and neoplasm type, and pose confusion for referring physicians and interpreting radiologists. The superior soft tissue resolution offered by magnetic resonance imaging is most useful in the surveillance of cancers with high propensities for intraorbital, intracranial, or perineural disease spread, which most commonly include those arising from the sinonasal cavities, nasopharynx, orbits, salivary glands, and the skin. This article discusses recommended surveillance protocoling and reviews treatment approaches, common posttreatment changes, and pearls for identifying disease recurrence in a subsite-based approach.

Utility of diffusion-weighted magnetic resonance imaging in predicting the treatment response of nasopharyngeal carcinoma

OBJECTIVE

Predicting the treatment response in patients with nasopharyngeal carcinoma (NPC) is challenging. This study evaluated the utility of diffusion-weighted imaging (DWI) in predicting the treatment response in patients with NPC.

METHODS

We prospectively enrolled 33 patients with newly diagnosed NPC who underwent magnetic resonance imaging with the propeller DWI and apparent diffusion coefficient (ADC) map before and at 5 weeks after chemoradiation. The following ADC values of the primary tumor were calculated: pre-treatment ADC (pre-ADC), pre-treatment ADC ratio (pre-ADC ratio), ADC change (▵ADC), ADC change ratio (▵ADC ratio), and percentage of ADC change (▵%ADC). The correlations between these parameters and treatment outcomes were explored, and the patients were classified as good responders (complete response) and poor responders (stable disease, partial response, or progressive disease) based on the Response Evaluation Criteria in Solid Tumors, version 1.1.

RESULTS

The ▵ADC, ▵ADC ratio, and ▵%ADC were significantly lower in the poor-responder group (n = 12) than in the good-responder group (n = 21; p = 0.001, p = 0.002, and p = 0.004, respectively). There was no significant difference between groups in the pre-ADC and pre-ADC ratios (p = 0.602 and p = 0.685, respectively). The optimal ▵ADC, ▵ADC ratio, and ▵%ADC cutoff values for predicting poor response were >0.65 mm²/sec, 0.28, and 60%, respectively (sensitivity: 83.3%, 75%, and 83.3%; specificity: 71.4%, 85.7%, and 71.4%, respectively).

CONCLUSION

The ▵ADC, ▵ADC ratio, and ▵%ADC obtained during the pre-treatment and mid-treatment periods could be potential biomarkers for predicting treatment response in patients with NPC.

Deep Learning-Guided Fiberoptic Raman Spectroscopy Enables Real-Time In Vivo Diagnosis and Assessment of Nasopharyngeal Carcinoma and Post-treatment Efficacy during Endoscopy

In this work, we develop a deep learning-guided fiberoptic Raman diagnostic platform to assess its ability of real-time in vivo nasopharyngeal carcinoma (NPC) diagnosis and post-treatment follow-up of NPC patients. The robust Raman diagnostic platform is established using innovative multi-layer Raman-specified convolutional neural networks (RS-CNN) together with simultaneous fingerprint and high-wavenumber spectra acquired within sub-seconds using a fiberoptic Raman endoscopy system. We have acquired a total of 15,354 FP/HW in vivo Raman spectra (control: 1761; NPC: 4147; and post-treatment (PT): 9446) from 888 tissue sites of 418 subjects (healthy control: 85; NPC: 82; and PT: 251) during endoscopic examination. The optimized RS-CNN model provides an overall diagnostic accuracy of 82.09% (sensitivity of 92.18% and specificity of 73.99%) for identifying NPC from control and post-treatment patients, which is superior to the best diagnosis performance (accuracy of 73.57%; sensitivity of 89.74%; and specificity of 58.10%) using partial-least-squares linear-discriminate-analysis, proving the robustness and high spectral information sensitiveness of the RS-CNN model developed. We further investigate the saliency map of the best RS-CNN models using the correctly predicted Raman spectra. The specific Raman signatures that are related to the cancer-associated biomolecular variations (e.g., collagens, lipids, and nucleic acids) are uncovered in the map, validating the diagnostic capability of RS-CNN models to correlate with biomolecular signatures. Deep learning-based Raman spectroscopy is a powerful diagnostic tool for rapid screening and surveillance of NPC patients and can also be deployed for longitudinal follow-up monitoring of post-treatment NPC patients to detect early cancer recurrences in the head and neck.

The evolution of bone marrow signal changes at the skull base in nasopharyngeal carcinoma patients treated with radiation therapy

BACKGROUND

Clival infiltration is frequently seen in nasopharyngeal carcinoma (NPC) and the resultant bone marrow signal changes (BMSC) can persist even after complete tumor response to the radiation therapy (RT). The differentiation of those residual BMSC from recurrent/persistent disease may be challenging. We performed serial analysis of the clival BMSC after RT, to define an expected temporal evolution of those signal changes during the follow-up.

MATERIALS AND METHODS

Serial MRI studies of 50 NPC patients (with or without initial clival infiltration) who had undergone RT were retrospectively examined. Abnormal clival BMSC and contrast enhancement (CE) were evaluated on each follow-up scan. Duration of BMSC/CE was correlated with the degree of baseline clival involvement (BCID), RT dose, and primary mass volume (PMV).

RESULTS

Clival BMSC persisted without any evidence of recurrence, for a mean of 66.5 (max. 137) months (with accompanying CE for up to 125 months) in 26 patients with clival infiltration at diagnosis. Duration of BMSC and CE showed statistical correlations with PMW (p < 0.05), but not with RT dose or BCID. The rate of recurrence in clivus was 14%. New clival lesions that occurred within the first 12 months after RT (in six patients) did not develop recurrence suggesting radiation osteitis (12%).

CONCLUSION

After RT, residual clival medullary signal change/enhancement is seen in most NPC patients and can persist even years without recurrence.

Image-based diagnosis of residual or recurrent nasopharyngeal carcinoma may be a phantom tumor phenomenon

Some nasopharyngeal carcinoma (NPC) patients may present convincing radiological evidence mimicking residual or recurrent tumor after radiotherapy. However, by means of biopsies and long term follow-up, the radiologically diagnosed residuals/recurrences are not always what they appear to be. We report our experience on this "phantom tumor" phenomenon. This may help to avoid the unnecessary and devastating re-irradiation subsequent to the incorrect diagnosis.In this longitudinal cohort study, we collected 19 patients of image-based diagnosis of residual/recurrent NPC during the period from Feb, 2010 to Nov. 2016, and then observed them until June, 2019. They were subsequently confirmed to have no residual/recurrent lesions by histological or clinical measures. Image findings and pathological features were analyzed.Six patients showed residual tumors after completion of radiotherapy and 13 were radiologically diagnosed to have recurrences based on magnetic resonance imaging (MRI) criteria 6 to 206 months after radiotherapy. There were 3 types of image patterns: extensive recurrent skull base lesions (10/19); a persistent or residual primary lesion (3/19); lesions both in the nasopharynx and skull base (6/19). Fourteen patients had biopsy of the lesions. The histological diagnoses included necrosis/ inflammation in 10 (52.7%), granulation tissue with inflammation in 2, and reactive epithelial cell in 1. Five patients had no pathological proof and were judged to have no real recurrence/residual tumor based on the absence of detectable plasma EB virus DNA and subjective judgment. These 5 patients have remained well after an interval of 38-121 months without anti-cancer treatments.Image-based diagnosis of residual or recurrent nasopharyngeal carcinoma may be unreliable. False positivity, the "phantom tumor phenomenon", is not uncommon in post-radiotherapy MRI. This is particularly true if the images show extensive skull base involvement at 5 years or more after completion of radiotherapy. MRI findings compatible with NPC features must be treated as a real threat until proved otherwise. However, the balance between under- and over-diagnosis must be carefully sought. Without a pathological confirmation, the diagnosis of residual or recurrent NPC must be made taking into account physical examination results, endoscopic findings and Epstein-Barr virus viral load. A subjective medical judgment is needed based on clinical and laboratory data and the unique anatomic complexities of the nasopharynx.

Label-Free Follow-Up Surveying of Post-Treatment Efficacy and Recurrence in Nasopharyngeal Carcinoma Patients with Fiberoptic Raman Endoscopy

Recurrent nasopharyngeal carcinoma (NPC) is the main cause of poor prognosis for NPC patients after chemo- and radiotherapies. Subsequent long-term follow-ups of post-treatment patients are crucial for the early discovery of tumor recurrence with timely intervention. Current clinical imaging methods based on tissue morphology encounter difficulties in differentiating recurrent tumors from post-treatment inflammation and fibrosis. In this work, we apply a unique fiberoptic Raman endoscopy technique to address the challenges for label-free follow-up surveying of post-treatment NPC patients and accurate detection of tumor recurrence. Significant Raman spectral differences can be observed among normal, NPC, and nonrecurring post-treatment patients. Raman endoscopy provides diagnostic accuracy of 100% for detecting recurrent NPC from early post-treatment inflammation and diagnostic accuracy of 98.21% for separating recurrent NPC from long-term post-treatment fibrosis. Further quantitative Raman modeling on in vivo nasopharyngeal tissue Raman data acquired unveils the changes of major tissue biochemicals (e.g., triolein, elastin, keratin, fibrillar collagen, and type IV collagen) associated with primary NPC and post-treatment recurrent NPC tissue compared to normal nasopharyngeal tissue. This work demonstrates that fiberoptic Raman endoscopy can be a clinically powerful diagnostic tool for rapid, label-free post-treatment surveying and recurrent tumor detection in NPC patients at the molecular level.

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.

The Management of rNPC: Salvage Surgery vs. Re-irradiation

PURPOSE OF REVIEW

Treatment failure, in the form of either persistence or local recurrence, occurs in 10 to 30% of nasopharyngeal carcinoma patients after initial radiotherapy (RT). Early detection of persistent or recurrent disease aids in the recognition of tumors that can be candidates for salvage nasophayngectomy or re-irradiation. There is no consensus till now on the indications or selection of the above two salvage treatment.

RECENT FINDINGS

In recent years, there has been a paradigm shift from open to endoscopic approach for nasopharyngectomy, which carries nearly no complications. For salvage re-irradiation, intensity-modulated radiotherapy (IMRT) is the most commonly indicated modality. Compared to IMRT, salvage endoscopic nasopharyngectomy may be more beneficial in terms of prolonging survival, improving quality of life, and minimizing treatment-related complications and medical costs in a selected subset of recurrent nasopharyngeal carcinoma (rNPC) patients. Salvage nasopharyngectomy should be the mainstay of treatment for rNPC.

Management of Recurrent or Progressing Skull Base Chondrosarcomas: Predictors of Long-Term Outcomes

Background  Skull base chondrosarcomas (CSA) are difficult tumors to cure and there is little data regarding salvage therapy. Objective  This study aims to identify presentation and treatment-related factors which impact the progression free survival (PFS) and disease specific survival (DSS) for recurrent CSA, and to identify salvage treatment factors associated with successful restoration to the natural history following primary treatment. Methods  This single-institution retrospective review included patients with recurrent/progressive CSA over a 25-year period. Survival analysis for factors impacting PFS and DSS was performed. Salvage treatment factors associated with achieving PFS ≥newly diagnosed median PFS were identified using univariate statistics. Analysis was performed on first recurrences and all recurrences combined. Results  A total of 47 recurrence/progression events were analyzed from 17 patients (median two events/patient, range = 1-8). The overall PFS and DSS for the initial recurrence was 32 (range = 3-267) and 79 (range = 3-285) months, respectively. Conventional grade III or mesenchymal histology significantly predicted shorter PFS and DSS ( p  < 0.0001). After stratification by histology, previous radiation predicted shorter PFS for low-grade tumors ( p  = 0.009). Gross total resection (GTR) after a first time recurrence was significantly associated with successful salvage treatment ( p  < 0.05); however, this was rare. Conclusion  In this series, high grade histology and prior radiation treatment negatively impacted salvage treatment outcomes, while GTR was associated with restoration to natural history following primary treatment. Careful consideration of histology, systemic disease status, previous treatments, and the anatomic extent of the skull base disease can optimize the outcomes of salvage intervention.

Correlation of PET-CT, MRI and histopathology findings in the follow-up of patients with nasopharyngeal cancer

Introduction

Surgical treatment options are limited for nasopharyngeal cancer for many reasons including epidemiological and histological properties, proximity to important structures, heavy lymphatic drainage, and the difficulty in ensuring a safe surgical margin; therefore primary treatment is generally radiotherapy and chemotherapy. With current radiotherapy technology, oncological success has been increased and the quality of life of patients during the post- radiotherapy period is improved.

Objective

The role of magnetic resonance imaging and positron emission-computed tomography in the follow-up of recurrent nasopharyngeal cancer patients who were initially treated with radiotherapy was evaluated with respect to histopathological findings.

Methods

A total of 110 patients with nasopharyngeal cancer who had received radiotherapy were included in the study. Patients who were suspected to have recurrence according to endoscopic nasopharyngeal examination and magnetic resonance imaging findings were requested to undergo positron emission-computed tomography. Biopsies were taken from 40 patients who had suspicious lesions in positron emission-computed tomography images. These patients’ age, gender, presence/absence of contrast enhancement on magnetic resonance imaging, the SuvMax values of nasopharyngeal and neck lesions, T/N phases at initial diagnosis, histopathological recurrence, and history of neck dissection were assessed.

Results

Recurrence was observed in 8 patients (20.0%). Among these, 4 (10.0%) had recurrence at the nasopharynx and 4 (10.0%) at the neck. Patients with recurrence were found to be of older age, male gender, advanced T/N phase, contrast enhancement on magnetic resonance imaging, and higher nasopharyngeal and neck SuvMax values in positron emission-computed tomography. However, these differences were not statistically significant. Only the history of neck dissection was significantly more common among those with recurrence (p < 0.001). However, in multivariate analysis, those with a nasopharyngeal SuvMax value higher than 4.58 were found to have 7.667-fold higher risk for recurrence (p = 0.036).

Conclusions

Magnetic resonance imaging and positron emission-computed tomography should be evaluated together in the follow-up of nasopharyngeal cancer. Patients with minimal SuvMax 4.58 on positron emission-computed tomography after contrast enhancement in the T2 sequence on magnetic resonance imaging may considered appropriate for biopsy. Biopsies in patients with a SuvMax value lower than 4.58 can be avoided. Thus, patients avoid surgical stress and unnecessary costs.

Hopkins criteria for residual disease assessment after definitive radiotherapy in nasopharyngeal carcinoma

Objectives

Assessment of viable tumor residue after definitive radiotherapy is essential in patients with nasopharyngeal carcinoma (NPC). This study aimed to investigate the use of Hopkins criteria on positron emission tomography/computed tomography (PET/CT) for posttreatment response evaluation and whether plasma Epstein‐Barr virus (EBV) DNA could bring additional value.

Materials and methods

NPC patients who underwent FDG‐PET/CT scan within 26 weeks after definitive radiotherapy were retrospectively reviewed. Residual disease was evaluated by Hopkins 5‐point score. Accuracy of Hopkins criteria before and after incorporating EBV DNA was calculated. Prognostic value for locoregional failure‐free survival (LRFFS) and disease‐free survival (DFS) was analyzed.

Results

One hundred and sixteen patients were evaluated. Median follow‐up time was 28.3 months (range 3.3‐92.0 months). Residual disease was found in 19 (16.4%) patients. Overall, Hopkins criteria had high specificity (86.6%; 95% CI, 78.2%‐92.7%) and negative prognostic value (NPV) (94.4%; 95% CI, 88.7%‐97.3%), while sensitivity and positive prognostic value (PPV) was 73.7% (95% CI, 48.8%‐90.9%), 51.9% (95% CI, 37.8%‐65.6%), respectively. Posttreatment plasma EBV DNA was not predictive of residual tumor (P = .272). PPV and accuracy were 50.0% (95% CI, 32.1%‐67.9%) and 83.0% (95% CI, 73.8%‐90.0%) after incorporating detectable EBV DNA into the scoring system. Positive PET/CT results were significantly correlated with inferior 3‐year LRFFS (95.7% vs 79.5%, P = .043) and 3‐year DFS (84.6% vs 54.4%, P = .028).

Conclusions

The Hopkins criteria demonstrated high NPV and specificity in posttreatment assessment, with the potential to be a reliable prognostic indicator for locoregional failure. Combining EBV DNA with PET/CT did not improve diagnostic accuracies. PET/CT should not be performed less than 12 weeks after treatment.

Posttreatment surveillance for sinonasal malignancy

PURPOSE OF REVIEW

Sinonasal neoplasms have a high rate of recurrence following treatment, and clinicians utilize a variety of surveillance techniques. Generally, surveillance modality and frequency of follow-up are determined by the guidelines for head and neck cancer as a broad category. However, recent studies have demonstrated that a more tailored approach to follow-up may be necessary.

RECENT FINDINGS

Endoscopy has low sensitivity in recurrence detection, especially in the asymptomatic patient. However, it is able to identify superficial recurrences that may be more amenable to repeat resection. Conversely, imaging [computed tomography (CT), MRI, and F-fluorodeoxyglucose-PET/CT] is useful in ruling out disease, but the inflammatory environment of the posttreatment sinonasal cavity leads to a high number of false positives. This is especially notable in PET/CT, which has worse specificity and positive predictive value in sinonasal malignancy than in head and neck malignancy overall, especially in the early posttreatment period. Little data are available on optimal timing and duration of follow-up, but tumor histology and aggressiveness should be considered when choosing a surveillance approach.

SUMMARY

Sinonasal malignancy surveillance strategies may warrant modifications of current protocols used for head and neck malignancy. This is due to a number of factors, including a greater diversity of sinonasal disorder and increased duration of posttreatment sinonasal inflammation. Clinicians should be aware of the performance parameters of commonly used surveillance techniques and adjust follow-up regimens based on this information.

Magnetic resonance imaging of swallowing-related structures in nasopharyngeal carcinoma patients receiving IMRT: Longitudinal dose-response characterization of quantitative signal kinetics

BACKGROUND

We aim to characterize serial (i.e., acute and late) MRI signal intensity (SI) changes in dysphagia-associated structures as a function of radiotherapy (RT) in nasopharyngeal cancer (NPC) patients.

MATERIALS AND METHODS

We retrospectively extracted data on 72 patients with stage III-IV NPC treated with intensity-modulated RT (IMRT). The mean T1- and T2-weighted MRI SIs were recorded for the superior pharyngeal constrictor (SPC) and soft palate (SP) at baseline, early-after IMRT, and last follow up, with normalization to structures receiving <5 Gy.

RESULTS

All structures had a significant increase in T2 SIs early after treatment, irrespective of the mean dose given. At last follow-up, the increase in T2 SI subsided completely for SPC and partially for SP. The T1 SI did not change significantly in early follow-up images of both structures; on late follow-up, patients with mean doses >62.25 Gy had a significant decrease in the corresponding T1 SI for SPC (1.6 ± 0.4 vs. 1.3 ± 0.4, P=0.007) but decreased non-significantly for SP.

CONCLUSIONS

Serial MRI acquisitions enable the identification of both early and late radiation-induced changes in swallowing structures after definitive IMRT for NPC. Dose dependent decrease in late T1 SI is associated with higher RT doses to the superior pharyngeal constrictor muscle; while dose independent increase in SI for both structures in early post-RT T2 images is observed and subsides after therapy. Further efforts will seek to elucidate the relationship between dose-dependent muscle SI changes and functional alteration of swallowing muscles.

Post-treatment Evaluation of Paranasal Sinuses After Treatment of Sinonasal Neoplasms

The aim of imaging in the follow-up of asymptomatic patients treated for sinonasal neoplasms is to detect submucosal relapsing lesions. The challenge is to discriminate recurrent tissue within the changes resulting from unpredictable healing of tissue after surgery and radiotherapy. Scar, inflammation, and recurrence can be better separated with a multisequence MR imaging approach. The choice of the field of view should take into account the risk of in-field intracranial recurrences, craniofacial bone metastases, and perineural spread. Fluorodeoxyglucose-PET has a role in assessing distant metastasis. Its usefulness in local and regional surveillance has yet to be established.

A retrospective study of the prognostic value of MRI-derived residual tumors at the end of intensity-modulated radiotherapy in 358 patients with locally-advanced nasopharyngeal carcinoma

Objective

To retrospectively analyze the prognostic value of magnetic resonance imaging (MRI)-derived residual tumors after intensity-modulated radiation therapy (IMRT) in the patients with locally-advanced nasopharyngeal carcinoma.

Methods

A total of 358 patients with locally-advanced nasopharyngeal carcinoma who received IMRT were classified as having residual tumors or no residual tumor based on MRI at the end of radiotherapy. The χ² test, log-rank test, Cox proportional hazards regression model and Kaplan-Meir survival curves were used to investigate the relationship of clinicopathological features and residual tumors and to assess the prognostic value of residual tumors.

Results

The 3-year overall survival (OS) rate was 73% in the residual tumor group and 90% in the no residual tumor group (HR 2.15, 95% CI 1.21-3.82,, P = 0.007); 3-year local relapse-free survival (LRFS) was 89% in the residual tumor group and 97% in the no residual tumor group (HR 4.46, 95% CI 1.61-12.38, P = 0.002); 3-year disease free survival (DFS) was 67% in the residual tumor group and 82% in the no residual tumor group (HR 2.21, 95% CI 1.40-3.48, P = 0.001). A high prescribed radiation dose (>73.92 Gy) did not increase the percentage volume of the GTVnx receiving 95% of the prescribed dose (GTVnx V95%) or improve any survival outcome.

Conclusion

The presence of a residual tumor after IMRT was a significant negative independent prognostic factor for OS, LRFS and DFS. Although IMRT have improved the distribution of radiotherapy doses into the tumors, residual tumors detected by MRI after IMRT are still associated with poor prognosis in patients with advanced nasopharyngeal carcinoma.

Osteoradionecrosis after radiation therapy for head and neck cancer: differentiation from recurrent disease with CT and PET/CT imaging

BACKGROUND AND PURPOSE

Our aim was to compare the CT and PET/CT imaging features of osteoradionecrosis with those of recurrent disease after treatment of head and neck malignancy.

MATERIALS AND METHODS

We retrospectively reviewed maxillofacial and neck CT scans obtained for suspected osteoradionecrosis or tumor recurrence for the presence of the following: 1) discrete solid mass, 2) cystic mass, 3) interruption of the bony cortex, 4) bony fragmentation, 5) bony trabecular loss, 6) intraosseous gas, and 7) bony sclerosis. Trabecular bone loss was further categorized as permeative (<75% loss of trabecula) or lucent (>75% loss). PET/CT studies performed for suspected osteoradionecrosis or tumor recurrence were evaluated for mean standard uptake value and maximum standard uptake value.

RESULTS

Ten maxillofacial CT, 53 neck CT, and 23 PET/CT studies were performed in 63 patients. Osteoradionecrosis was diagnosed by pathology or imaging stability in 46 patients, and tumor recurrence, in 17 patients. Bony sclerosis was found to be significantly more prevalent in osteoradionecrosis and was never seen with tumor recurrence (P = .013). Patients with tumor recurrence were more likely to have a solid (P < .001) or cystic mass (P = .025), which was rare in osteoradionecrosis. While patients with tumor recurrence had significantly higher mean standard uptake values and maximum standard uptake values, there was significant overlap in mean standard uptake values and maximum standard uptake values between the 2 groups.

CONCLUSIONS

There is significant overlap of standard uptake values in patients with osteoradionecrosis and tumor recurrence. CT findings provide more reliable diagnostic tools, with a solid or cystic mass strongly associated with tumor recurrence and bony sclerosis seen only with osteoradionecrosis.

Imaging appearances for recurrent nasopharyngeal carcinoma and post-salvage nasopharyngectomy

Nasopharyngeal carcinoma (NPC) is a head and neck neoplasm that occurs in endemic numbers among people of southern Chinese descent. External beam radiation to the nasopharyngeal bed and primary draining lymph node echelons is the mainstay of treatment with concurrent cisplatin-based chemotherapy for more advanced disease. Detection of residual and/or recurrent NPC has important clinical implications, as salvage protocols are available. The review aims to increase awareness of the imaging features of NPC recurrences at local and distant sites using computed tomography (CT), magnetic resonance imaging (MRI), and positron-emission tomography (PET). Important changes in imaging seen in patients after nasopharyngectomy are also discussed.

MRI and CT of nasopharyngeal carcinoma

OBJECTIVE

This article reviews the MRI and CT of nasopharyngeal carcinoma. Extension of nasopharyngeal tumors, especially into the skull base and the deep facial spaces, is well illustrated on imaging. Assessment of retropharyngeal and cervical lymphadenopathy is important for treatment planning. MRI is commonly used for monitoring patients after therapy.

CONCLUSION

Imaging can detect effect of radiation on surrounding structures. The imaging findings that help to differentiate nasopharyngeal carcinoma from simulating lesions are discussed.

The postradiation neck: evaluating response to treatment and recognizing complications

OBJECTIVE

We summarize the rationale for and physiology of radiation therapy for the treatment of head and neck cancer and review the imaging findings of expected changes and complications after radiation to the neck. It is important to be able to recognize these features at all stages during management of patients with squamous cell carcinoma and other head and neck malignancies and to be able to distinguish these changes from residual or recurrent disease.

CONCLUSION

Radiation therapy results in imaging findings of tissue edema followed by fibrosis, scarring, and atrophy. Complications from radiation therapy can occur months to years after treatment. Findings of a new mass, lymphadenopathy, or bone or cartilage destruction must be viewed as concerning for recurrent disease.

[Imaging of nasopharyngeal diseases]

This article gives an overview about the main nasopharyngeal pathologies and incidental findings, which a radiologist could be confronted with in daily practice. These include nasopharyngeal cysts, lymphoid hyperplasia, juvenile angiofibroma, carcinomas and non-Hodgkin lymphoma. Typical radiological findings, possibilities for making a specific diagnosis, differential diagnosis and description of the spread of a neoplasm are the central points. Investigation techniques and clinical signs are briefly summarized.

Postirradiation Sinus Mucosa Disease in Nasopharyngeal Carcinoma Patients

OBJECTIVES/HYPOTHESIS

We sought to determine the incidence, progression, and risk factors for postirradiation sinus mucosa diseases (SMD) incidentally found on follow-up magnetic resonance images MRIs) in nasopharyngeal carcinoma (NPC) patients.

STUDY DESIGN

RETROSPECTIVE.

METHODS

The medical records, pre- and postradiotherapy (RT) MRIs were reviewed in NPC patients. Lund-Mackay system for staging of rhinosinusitis (Lund score) was used as a tool for investigation.

RESULTS

One hundred twelve NPC patients (77 males and 35 females) were recruited in this study. The distribution of tumor staging in these patients were 39 (34.8%) patients in T1,23(20.5%) in T2, 31(27.7%) in T3, and 19 (17.0%) in T4 by MRI staging before RT. In these 62 patients with normal sinus ventilation before RT, 42 (67.7%) patients returned to having SMDs 3 months after RT. The maxillary,anterior ethmoid, and posterior ethmoid sinuses were most readily affected. In patients with SMDs at 3 months postRT, advanced tumor stage (P = .013) and smoking habit (P =.047) were the two factors that significantly influence Lund score. When comparing Lund score with different times after radiation therapy, a trend of decrease in Lund score could be noted from 3 months to 3 years after irradiation.

CONCLUSIONS

The incidence and severity of SMD was found to be highest at 3 months postRT and decreased gradually with time. Conservative management with clinical symptom correlation should be attempted first in these patients. In these NPC patients,advanced tumor stage and smoking habit would predispose them to SMD development.

Advantages and pitfalls of 18F-fluoro-2-deoxy-D-glucose positron emission tomography in detecting locally residual or recurrent nasopharyngeal carcinoma: comparison with magnetic resonance imaging

INTRODUCTION

This prospective study was designed to elucidate the advantages and pitfalls of (18)F-FDG PET in detecting locally residual/recurrent nasopharyngeal carcinoma (NPC) in comparison with MRI.

METHODS

We recruited NPC patients from two ongoing prospective trials. One is being performed to evaluate suspected local recurrence (group A) and the other to assess local treatment response 3 months after therapy (group B). Both groups received (18)F-FDG PET and head and neck MRI. The gold standard was histopathology or clinical/imaging follow-up. An optimal cut-off standardised uptake value (SUV) was retrospectively determined.

RESULTS

From January 2002 to August 2004, 146 patients were eligible. Thirty-four were from group A and 112 from group B. In all, 26 had locally recurrent/residual tumours. Differences in detection rate between (18)F-FDG PET and MRI were not statistically significant in either group. However, (18)F-FDG PET showed significantly higher specificity than MRI in detecting residual tumours among patients with initial T4 disease (p=0.04). In contrast, the specificity of (18)F-FDG PET for patients with an initial T1-2 tumour treated with intracavitary brachytherapy (ICBT) was significantly lower than that for patients not treated by ICBT (72.2% vs 98.1%, p=0.003). At an SUV cut-off of 4.2, PET showed an equal and a higher accuracy compared with MRI in groups A and B, respectively.

CONCLUSION

(18)F-FDG PET is superior to MRI in identifying locally residual NPC among patients with initial T4 disease but demonstrates limitations in assessing treatment response in patients with initial T1-2 disease after ICBT. A cut-off SUV is a useful index for aiding in the visual detection of locally residual/recurrent NPC.

Nasopharyngeal carcinoma with cranial nerve palsy: the importance of MRI for radiotherapy

PURPOSE

To evaluate various prognostic factors and the impact of imaging modalities on tumor control in patients with nasopharyngeal cancer (NPC) with cranial nerve (CN) palsy.

MATERIAL AND METHODS

Between September 1979 and December 2000, 330 NPC patients with CN palsy received radical radiotherapy (RT) by the conventional opposing technique at Chang Gung Memorial Hospital-Linkou. Imaging methods used varied over that period, and included conventional tomography (Tm) for 47 patients, computerized tomography (CT) for 195 patients, and magnetic resonance image (MRI) for 88 patients. Upper CN (II-VI) palsy was found in 268 patients, lower CN (IX-XII) in 13, and 49 patients had both. The most commonly involved CN were V or VI or both (23%, 12%, and 16%, respectively). All patients had good performance status (World Health Organization <2). The median external RT dose was 70.2 Gy (range, 63-77.5 Gy). Brachytherapy was also given to 156 patients in addition to external RT, delivered by the remote after-loading, high-dose-rate technique. A total of 139 patients received cisplatin-based chemotherapy, in 115 received as neoadjuvant or adjuvant chemotherapy and in 24 concomitant with RT. Recovery from CN palsy occurred in 171 patients during or after radiotherapy. Patients who died without a specific cause identified were regarded as having died with persistent disease.

RESULTS

The 3-year, 5-year, and 10-year overall survival was 47.1%, 34.4%, and 22.2%. The 3-year, 5-year, and 10-year disease-specific survival (DSS) rates were 50.4%, 37.8%, and 25.9%. The 5-year DSS for patients staged with MRI, CT, and Tm were 46.9%, 36.7%, and 21.9%, respectively (p = 0.016). The difference between MRI and CT was significant (p = 0.015). The 3-year and 5-year local control rates were 62% and 53%, respectively. The 5-year local control was 68.2% if excluding patients who died without a specific cause. Patients who had an MRI had a significantly better tumor control rate than those evaluated with CT or Tm, with a 15-30% improvement in local tumor control and survival. Patients with extensive CN palsy had worse survival than those with only lower CN or upper CN involvement (5-year DSS 20.4% vs. 43.2% and 40.4%, respectively; p < 0.001). Patients who recovered from CN palsy had better survival than those who did not (47% vs. 26%, p < 0.001). Brachytherapy was associated with poorer local control, whereas a total external dose of more than 70 Gy improved local tumor control and marginally improved DSS. Subgroup analysis in CT and MRI patients group, either DSS or OS was significantly associated with imaging modality, N stage, or location of or remission of CN palsy.

CONCLUSION

The use of MRI was associated with improved tumor control and survival of patients with NPC causing CN palsy. Patients recovering from CN palsy had better survival. A higher radiation dose delivered by external beam may achieve better tumor control than brachytherapy.

[Target volumes in radiotherapy - head and neck tumors intensity - modulated radiation therapy (IMRT) of nasopharyngeal carcinoma: practical aspects in the delineation of target volumes and organs at risk]

The objective of this paper is to give some practical landmarks for the delineation of target volumes and organs at risk in Intensity Modulated Radiation Therapy for Nasopharyngeal Carcinoma. This delineation, drawn from anatomo-clinical data, natural history of the disease and radiological pre-treatment evaluation, seems to be easier to define than the delineation of other head and neck cancer localisations (oropharynx and oral cavity for example). Experience inside national and international cooperative groups should tend to standardize this initial and fundamental step of Nasopharyngeal Conformal Radiotherapy.

Nasopharynx

NPC represents 0.2% of malignant disease in the white population but is more common in southern China, among Chinese in East Asia and the United [figure: see text] States, and in North Africa, including Saudi Arabia. NPC in these ethnic groups tends to manifest at a younger age. Undifferentiated carcinoma is the most common histopathologic type and is associated with EBV. The tumor is optimally assessed with CT and MR imaging for staging; PET scanning provides optimal assessment of recurrent tumor or small lymph node metastases. The primary tumor in the nasopharynx may be small and infiltrating, causing no or only a small mass effect in the nasopharynx. In these cases, obliteration of fat planes and loss of muscle boundaries are important diagnostic findings, which are best evaluated with MR imaging including, Gd-DTPA with fat suppression. The size of the NPC varies from 1 to 2 cm to large tumors that extend to the oropharynx, PPS, nasal cavities, paranasal sinuses, and orbits. Skull base erosion is independent of the size of the nasopharyngeal tumor and ranges from slight erosion to extensive destruction. A concomitant finding is intracranial invasion, predominantly to the basal cisterns and cavernous sinuses associated with cranial nerve palsies. Intracranial invasion should be assessed with contrast MR imaging. Lymph node metastases in the neck are present in 90% of cases and are bilateral in 50% of cases. In a small percentage of cases, extension of lymph node metastases to the mediastinum and hilar areas are encountered. Distant metastases involve the lungs, skeleton, and liver, and occasionally the choroid. They are usually present at the initial presentation [figure: see text] and increase in frequency in advanced disease and in recurrent tumors. In addition, the metastatic lymph nodes in the neck reveal no specific imaging features that would allow differentiation from other lymph node metastases. They may be discrete, often multiple, and large and bulky displaying a variable degree of necrosis and enhancement following introduction of contrast material. Local recurrence manifests commonly within the first 2 to 3 years posttherapy and is optimally evaluated by MR imaging and PET scanning.