MRI of nasopharyngeal carcinoma with emphasis on relationship to radiotherapy

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.

Research progress on mechanism and dosimetry of brainstem injury induced by intensity-modulated radiotherapy, proton therapy, and heavy ion radiotherapy

Radiotherapy (RT) is an effective method for treating head and neck cancer (HNC). However, RT may cause side effects during and after treatment. Radiation-induced brainstem injury (BSI) is often neglected due to its low incidence and short survival time and because it is indistinguishable from intracranial tumor progression. It is currently believed that the possible mechanism of radiation-induced BSI includes increased expression of vascular endothelial growth factor and damage of vascular endothelial cells, neurons, and glial cells as well as an inflammatory response and oxidative stress. At present, it is still difficult to avoid BSI even with several advanced RT techniques. Intensity-modulated radiotherapy (IMRT) is the most commonly used therapeutic technique in the field of RT. Compared with early conformal therapy, it has greatly reduced the injury to normal tissues. Proton beam radiotherapy (PBT) and heavy ion radiotherapy (HIT) have good dose distribution due to the presence of a Bragg peak, which not only results in better control of the tumor but also minimizes the dose to the surrounding normal tissues. There are many clinical studies on BSI caused by IMRT, PBT, and HIT. In this paper, we review the mechanism, dosimetry, and other aspects of BSI caused by IMRT, PBT, and HIT.Key Points• Enhanced MRI imaging can better detect radiation-induced BSI early.• This article summarized the dose constraints of brainstem toxicity in clinical studies using different techniques including IMRT, PBT, and HIT and recommended better dose constraints pattern to clinicians.• The latest pathological mechanism of radiation-induced BSI and the corresponding advanced treatment methods will be discussed.

Positron emission tomography/computed tomography outperforms MRI in the diagnosis of local recurrence and residue of nasopharyngeal carcinoma: An update evidence from 44 studies

Studies on nasopharyngeal carcinoma (NPC) in five electronic databases were systematically searched online from the inception to June 5, 2018. Quality of the included studies was assessed using the updated Quality Assessment of Diagnostic Accuracy Studies 2. Data of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and the 95% confidence intervals were pooled using a bivariate random‐effect model. Forty‐four studies with 61 groups of data and totally 3369 patients were included in the qualitative and quantitative synthesis analysis. The overall estimated sensitivity and specificity of positron emission tomography/computed tomography/magnetic resonance imaging (PET‐CT/MRI) for local recurrent/residual NPC were 0.90 and 0.85, respectively. The pooled area under the curve of (AUC) of PET‐CT/MRI in the summary receiver operator characteristic curve was 0.94. Subgroup analysis showed MRI vs PET‐CT had lower sensitivity (0.83 vs 0.92) and specificity (0.78 vs 0.89). The AUCs of MRI and PET‐CT were 0.87 and 0.96, respectively. No‐cross of 95% CI was found in MRI vs PET/CT (0.87‐0.90 vs 0.94‐0.98). Meta‐regression showed PET/CT vs MRI was a potential source of heterogeneity. PET/CT and MRI both showed quite high overall ability in diagnosing local recurrent/residual NPC, but the subgroup analysis indicated PET‐CT was superior over MRI in diagnosis of local recurrence and residue of NPC after radiotherapy. The examination methods affected the heterogeneity within studies.

18F-FDG PET/CT for the Diagnosis of Residual or Recurrent Nasopharyngeal Carcinoma After Radiotherapy: A Metaanalysis

The aim of this work was to assess the overall value of (18)F-FDG PET/CT in the diagnosis of residual or recurrent nasopharyngeal carcinoma using a metaanalysis.

METHODS

The literature published between January 1990 and September 2014 was searched in the PubMed, EMBASE, Cochrane Library, EBSCO, VIP, CNKI, and Wanfang databases to identify eligible studies on PET/CT of residual or recurrent lesions. The methodologic quality of the included studies was evaluated using the "quality assessment for studies of diagnostic accuracy" tool. Summary sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and receiver-operating characteristic curve were obtained using Meta-DiSc freeware. Subgroups were also analyzed.

RESULTS

A total of 23 studies, involving 1,253 subjects, were included in the metaanalysis. Pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio, with 95% confidence intervals in parentheses, for (18)F-FDG PET or PET/CT were 0.93 (0.91-0.95), 0.87 (0.84-0.89), 5.52 (3.96-7.71), 0.12 (0.09-0.15), and 55.31 (34.94-87.57), respectively. The area under the receiver-operating characteristic curve and Q* index estimate of PET/CT were 0.9473 and 0.8869, respectively. There was no significant difference between the area under the curve of PET and PET/CT (P > 0.05).

CONCLUSION

Our study has confirmed that (18)F-FDG PET/CT has high sensitivity and specificity but significant heterogeneity in the diagnosis of residual or recurrent nasopharyngeal carcinoma.

Sonographic findings of nasopharyngeal carcinoma and its involvement in the parapharyngeal space

OBJECTIVES

The purpose of this study was to determine the sonographic performance in pathologically proven cases of nasopharyngeal carcinoma and its involvement in the parapharyngeal space.

METHODS

The study included 58 patients being treated for suspected nasopharyngeal carcinoma detected by routine nasopharyngoscopy who underwent pathologic biopsy. Sonography was performed immediately thereafter with a convex array transducer in both the B-mode and color mode. Forty-five of the 58 patients (90 parapharyngeal spaces) in whom nasopharyngeal carcinoma was proved by both sonography and pathologic biopsy underwent preradiotherapy magnetic resonance imaging (MRI). The sonographic findings were compared to the pathologic findings. The sonographic findings of parapharyngeal space involvement were correlated with the MRI findings.

RESULTS

The normal anatomy of the nasopharynx and parapharyngeal space, nasopharyngeal carcinoma, and its relationship with the parapharyngeal space were well shown on sonography. The sensitivity of sonography for detection of nasopharyngeal carcinoma was 97.8%, and the specificity was 41.7%. The sonographic findings of parapharyngeal space involvement had a high degree of agreement with MRI (κ = 0.757; P < .001).

CONCLUSIONS

These promising initial data indicate that sonography may be a useful tool for diagnosing nasopharyngeal carcinoma and defining the relationship between the tumor and the parapharyngeal space.

Staging of untreated nasopharyngeal carcinoma with PET/CT: comparison with conventional imaging work-up

PURPOSE

We prospectively compared PET/CT and conventional imaging for initial staging of nasopharyngeal carcinoma (NPC).

METHODS

A total of 111 patients with histologically proven NPC were investigated with PET/CT and conventional imaging (head-and-neck MRI, chest X-ray, abdominal ultrasound, and bone scan) before treatment. The respective findings were reviewed independently and then compared with each other.

RESULTS

With regard to T staging, PET/CT showed a discrepancy with head-and-neck MRI in 36 (32.4%) of the study subjects. With regard to N staging, PET/CT showed a discrepancy with head-and-neck MRI in 15 (13.5%) patients. Among the discordant cases, MRI was superior in demonstrating tumor involvement in the parapharyngeal space, skull base, intracranial area, sphenoid sinus, and retropharyngeal nodes while PET/CT was superior in demonstrating neck nodal metastasis. PET/CT disclosed 13 of 16 patients with distant malignancy compared with four patients disclosed by conventional imaging work-up. The false-positive rate of PET/CT was 18.8%. PET/CT correctly modified M staging in eight patients (7.2%) and disclosed a second primary lung malignancy in one patient (0.9%).

CONCLUSION

In NPC patients, MRI appears to be superior to PET/CT for the assessment of locoregional invasion and retropharyngeal nodal metastasis. PET/CT is more accurate than MRI for determining cervical nodal metastasis and should be the better reference for the neck status. PET/CT has an acceptable diagnostic yield and a low false-positive rate for the detection of distant malignancy and can replace conventional work-up to this aim. PET/CT and head-and-neck MRI are suggested for the initial staging of NPC patients.

18F-FDG-PET for evaluation of the response to concurrent chemoradiation therapy with intensity-modulated radiation technique for Stage T4 nasopharyngeal carcinoma

PURPOSE

This article evaluates [18F] fluorodeoxyglucose positron emission tomography (18F-FDG-PET) findings as a predictor for local responders (R) vs. nonresponders (NR) in nasopharyngeal carcinoma (NPC) patients with Stage T4 lesions, before and at 3 months after completion of concurrent chemotherapy and radiation therapy (CCRT).

METHODS AND MATERIALS

From January 2002 to November 2003, 39 T4 NPC patients were enrolled. All had magnetic resonance imaging and 18F-FDG-PET, both before and 3 months after CCRT. Any residual/recurrent lesions were confirmed histopathologically.

RESULTS

Of the 39 eligible patients, after a follow-up of 24.2 +/- 9.5 months, 35 became disease-free and 4 had residual or recurrent disease. Marginal differences in standard uptake values (SUV) were observed (10.9 +/- 5.3 vs. 15.6 +/- 3.4, p = 0.058) between R and NR before treatment, and value changes of SUV before and after CCRT were not significantly different. However, highly significantly lower values of SUV were noted for R than for NR 3 months after completion of CCRT (2.1 +/- 0.8 vs. 5.5 +/- 3.2, p = 0.001). One hundred percent positive and negative predictive values were observed for SUV values of 4.0, set 3 months after completion of CCRT.

CONCLUSIONS

Neither the pretreatment SUV nor the changes of SUV between pretreatment and posttreatment were significant predictors for local response. SUV at 3 months after completion of CCRT was a significant determinator for local response. The cutoff of 4.0 for SUV at 3 months after completion of CCRT was useful to be offered as a diagnostic reference for recurrent or residual tumor for NPC treatment.

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.

Influence of MRI abnormality in skull base bone on prognosis of nasopharyngeal carcinoma

PURPOSE

To evaluate the influence of skull base bone (SBB) abnormality showed by MRI on prognosis of nasopharyngeal carcinoma (NPC).

PATIENTS AND METHODS

From March 1993 to December 1998, 122 NPC patients received prime radiotherapy treatment. All of them were proved pathologically and checked by magnetic resonance imaging (MRI). Every patient received radiation through conjoint facio-cervical field and conventional dose-fractionation schedules. The total dose to the primary tumor was 60-75 Gy (median, 70 Gy). The Kaplan-Meier method, the Log-rank test and the Cox regression model were used to evaluate the significance of prognostic factors on NPC patient survival.

RESULTS

The overall median survival period was 50 (6-92) months, and the 1, 3 and 5 year-survival rates were, respectively, 99.2%, 87.9%, and 73.3%. The 1, 3, and 5 year-survival rates of abnormality and normality of the SBB on MRI were 98.9%, 87.2%, 71.9%, and 100.0%, 89.8%, 77.0%, respectively (P = 0.4233). Gender, age, head pain, SBB abnormality, cranial nerve palsy, cervical lymphadenopathy and primary tumor extent were analyzed with the Cox regression model and SBB abnormality on MRI did not prove to have statistical significance (P = 0.6934). According to the analysis of regrouping, patients with SBB abnormalities > or =2 sites have a worse prognosis (P = 0.0427). Then, the above seven factors are analyzed by Cox regression model and the result had statistical significance (P = 0.0385).

CONCLUSION

The SBB abnormality on MRI is of no obvious influence on prognosis of NPC. However, when SBB abnormality sites were > or =2, there is obvious statistical significance on the prognosis.

Semi-quantitative assessment of oral cavity squamous cell carcinoma using201 TI SPECT for evaluating effectiveness of preoperative radiotherapy

The aim of this study is to reveal the usefulness of semi-quantitative assessment using 201Tl chloride (Tl) single photon emission computed tomography (SPECT) (Tl SPECT) to evaluate the effectiveness of radiotherapy in 15 patients with oral cavity squamous cell carcinma (SCC). Fifteen patients were diagnosed with SCC by biopsy. All 15 patients enrolled in this study were planned to undergo preoperative radiotherapy with or without chemotherapy using carboplatin (CBDCA) and received reduction operation. Tl SPECTs were performed 15 minutes after intravenous administration of 111 MBq 201Tl chloride. Regions of Interest (ROI) were set up around tumor (T), and non-lesion (N) at the part of contralateral scalp at the height of the cerebellum. The ratios of mean counts in ROI of the tumor to those in non-lesion were measured as pre- and post-treatment T/N ratios (pre T/N, post T/N). Furthermore, reduction rate (RR) was obtained by calculating [(pre T/N - post T/N)/(pre T/ N)] x 100%. Each parameter (pre T/N, post T/N, and RR) was compared to histopathological grade of surgical specimen based on the Oboshi and Shimosato classification (grade I-IV). RR showed significantly higher values in grade III and IV than in grade I and II (p = 0.0008). In conclusion, semi-quantitative assessment using Tl SPECT, especially calculating RR, is useful to evaluate the effectiveness of preoperative radiotherapy.

Detection of Recurrent Nasopharyngeal Carcinomas After Radiotherapy with Technetium-99m Tetrofosmin Single Photon Emission Computed Tomography in Patients with Indeterminate Magnetic Resonance Imaging Findings

The aim of this study is to evaluate the effectiveness of technetium-99m tetrofosmin (Tc-99m TF) single photon emission computed tomography (SPECT) of head and neck for detecting suspected recurrence of nasopharyngeal carcinomas (NPCs) when magnetic resonance imaging (MRI) findings are indeterminate. MRI was performed 4 months after radiotherapy and 26 NPC patients with indeterminate MRI findings were included. MRI, Tc-99m TF SPECT, and biopsy were performed within 1 week. The final results were based on histopathologic findings and clinical follow-up for at least 6 months. For detecting recurrent NPC in indeterminate MRI findings, the sensitivity, specificity, and accuracy of Tc-99m TF SPECT were 92.3%, 100.0%, and 96.2%, respectively. Based on this result, we can suggest Tc-99m TF SPECT is effective to detect recurrent NPC when MRI findings are indeterminate. However, further studies including a larger NPC patient population are warranted to determine the exact role and clinical usefulness of Tc-99m TF SPECT to differentiate benign lesions and recurrent NPC when MRI findings are indeterminate.

Nasopharyngeal carcinoma: posttreatment changes of imaging findings

OBJECTIVE

The purpose of this study was to determine the radiologic results of nasopharyngeal carcinoma (NPC) that showed complete responses on follow-up imaging studies after radiation therapy.

MATERIALS AND METHODS

This study is a retrospective review of 23 patients (18 male, 5 female, aged 15-71 years; mean age, 48.5 years) affected with NPC, from August 1995 to July 2000, who were examined with magnetic resonance imaging or computed tomography scan before and after either radical radiotherapy or chemoradiotherapy. The median follow-up was 24.7 months and ranged from 12 to 48 months. We analyzed the primary tumors by ascertaining/measuring tumor size, depth, middle ear effusion, skull base invasion, and lymphadenopathy. The treatment responses for primary tumors were classified as either atrophy, scar (asymmetric elevation without enhancement), or normalized. The tumor response and the appearance of bone regeneration in the previous destructive part of the skull base were also recorded.

RESULTS

The 23 patients consisted of 12 superficial tumors, for whom treatment results were normalized in 10, atrophy in 1, and scar in 1 and 11 deep tumors for whom treatment results were scar in 6, normalized in 3, and atrophy in 2. Skull base invasion was detected in 6 patients, 5 of whom showed complete healing of skull base destruction after radiotherapy. However, the other patient exhibited an unusual hyperostotic change in the skull base mimicking fibrous dysplasia of the skull base.

CONCLUSIONS

The superficial tumors tended to be radiologically normalized even when they were large. However, the deep tumors mainly changed to scar after radiation therapy. On the other hand, skull base invasion could be normalized after radiotherapy.

Neurological changes following radiation therapy for head and neck tumours

Radiation therapy is widely used in the treatment of head and neck tumours either as a primary form of treatment or a supplementary modality. Although the benefits of radiation therapy are well established, this treatment modality is not without untoward consequences and complications. The intent of this paper is to highlight the neurological complications that may follow the treatment for head and neck malignancies, in particular, following radiation therapy for nasopharyngeal carcinoma.

Posttreatment imaging of the nasopharynx

Nasopharyngeal carcinoma (NPC) is the most common epithelial tumor of the nasopharynx. Radiation therapy is the mainstay of treatment while surgery or chemotherapy is used in selected patients. NPC usually regresses after 3 months of radiation therapy. Nonetheless, a residual mass may be present following treatment and this does not necessarily indicate viable tumor. Imaging studies are often used in conjunction with clinical examination following treatment. While computed tomography (CT) is widely used due to its greater availability, less expensive, and less time consuming, MR imaging is now becoming the preferred modality. MR imaging is more capable than CT for identifying mature scarring, tumor recurrence and postradiation complications. However, MR imaging cannot reliably demonstrate mucosal recurrence or differentiate tumor recurrence from postradiation tissue changes. Familiarity with the imaging findings of various posttreatment changes, tumor recurrence and postradiation complications is essential for management of NPC. Comparison with previous images or imaging-guided biopsy facilitates definitive diagnosis.

Skull-base invasion of nasopharyngeal carcinoma: magnetic resonance imaging findings and therapeutic implications

PURPOSE

To evaluate the value of skull-base abnormality on MRI for predicting local recurrence in nasopharyngeal carcinoma.

MATERIALS AND METHODS

Between November 1988 and February 1997, 48 patients with NPC were examined with both MRI (1.5 T) and CT prior to radiation therapy. T classification (1987 UICC) based on physical examination and CT findings were T1 in 3 cases, T2 in 22, T3 in 9, and T4 in 14. On MRI, low-intensity tissue with Gd enhancement in the marrow of the skull was considered to be a suspicious finding of skull-base invasion. CT simulation was performed in all patients. The total dose to the primary tumor was 60-75 Gy (mean, 67 Gy). The mean follow-up period was 42 months.

RESULTS

All 14 T4 patients had abnormal tissue in the marrow of the skull base on MRI. Thirty-eight percent (13 of 34) of T1-3 patients were suspected to have skull-base invasion based on MRI (0% for T1, 27% [6 of 22] for T2, and 78% [7 of 9] for T3). The 5-year local control rate was significantly different between T1-3 and T4 tumors (97% vs. 69%, p < 0.025) but was not different by the presence of the MRI abnormality in the skull base.

CONCLUSION

Skull-base invasion suspected solely by MRI does not relate to local recurrence provided that careful treatment planning is performed with the aid of MRI and CT simulator.

Paranasal sinuses and nasopharynx CT and MRI

Neoplastic disease of the nose, paranasal sinuses, the nasopharynx and the parapharyngeal space requires thorough assessment of location and extent in order to plan appropriate treatment. CT allows the deep soft tissue planes to be evaluated and provides a complement to the physical examination. It is especially helpful in regions involving thin bony structures (paranasal sinuses, orbita); here CT performs better than MRI. MRI possesses many advantages over other imaging modalities caused by its excellent tissue contrast. In evaluating regions involving predominantly soft tissue structures (ec nasopharynx and parapharyngeal space) MRI is superior to CT. The possibility to obtain strictly consecutive volume data sets with spiral CT or 3D MRI offer excellent perspectives to visualize the data via 2D or 3D postprocessing. Because head and neck tumors reside in a complex area, having a 3D model of the anatomical features may assist in the delineation of pathology. Data sets may be transferred directly into computer systems and thus be used in computer assisted surgery.

Locally recurrent nasopharyngeal carcinoma

PURPOSE

To assess the outcome of and determine prognostic factors for locally recurrent nasopharyngeal carcinoma (NPC) in patients treated with a second course of radiotherapy (RT).

MATERIALS AND METHODS

From 1982 to 1995, 186 NPC patients, who had initially been treated in the Department of Radiation Oncology, Chang Gung Memorial Hospital-Linkou, developed local recurrence in the nasopharynx and were re-treated with RT (>/=20 Gy). The time from the initial RT to re-treatment ranged from 8 to 136 months (median: 23 months). All patients were treated with external RT and conformal radiotherapy was used in 35 patients after 1993. Fifteen received radiosurgery as a boost treatment. The RT dose at the nasopharyngeal tumor area ranged from 20 to 67.2 Gy (median 50 Gy). Eighty-two patients received one to eight courses of cisplatin-based chemotherapy in addition to RT.

RESULTS

The 1-, 3- and 5-year survival was 54.9, 22. 1 and 12.4%, respectively. Patients whose tumor relapsed later than 2 years after the first treatment had a better survival than those with earlier relapse (3-year survival: 30.1 vs. 10.8%; P=0.015), but the difference became insignificant in patients who received >/=50 Gy. Patients without evidence of intracranial invasion or cranial nerve palsy had better survival than those with such lesions (3-year survival: 30.9 vs. 3.7%; P=0.006). A re-treatment dose >/=50 Gy yielded better survival (3-year survival: 22.8 vs. 18.5%; P=0.003). Addition use of radiosurgery may improve survival. The use of chemotherapy did not improve survival. Conformal radiotherapy resulted in significantly fewer severe complications than conventional RT.

CONCLUSIONS

A repeat course of RT for locally recurrent NPC successfully prolongs survival in a significant number of patients. Intracranial invasion and/or cranial nerve palsy and re-treatment dose affect the prognosis, with a dose of >/=50 Gy significantly improving survival. Radiosurgery boost may also improve survival. Our preliminary data indicates that conformal radiotherapy may decrease the severity of radiation-induced complications. However; longer follow-up and larger sample size is necessary to document the findings.

Nasopharyngeal carcinoma: review of how imaging affects staging

Imaging plays an important role in the staging of carcinoma of the nasopharynx. Accurate staging is necessary as the treatment is directly dependent on stage. Clinical examination provides information on mucosal involvement but is unable to determine the deep extension or presence of skull base invasion or intracranial spread. The 1997 International Union Against Cancer (UICC) and American Joint Committee on Cancer (AJCC) staging manuals were a collaborative project that provided a unified classification for nasopharyngeal carcinoma (NPC). The majority of staging can be identified only on imaging and not by clinical examination. The intent of this article is to provide information on the specific imaging findings that will directly affect the stage and treatment of NPC.