诊断

Review

Nasopharyngeal Carcinoma: Imaging Diagnosis and Recent Progress

Rakesh Maharjan, Zhanwang Xiang, Feng Shi, Ketong Wu, Chuanxing Li

 

Department of Medical Imaging & Interventional Radiology, Cancer Center and State Key Laboratory of Oncology in South China, Sun Yat-sen University, Guangzhou, 510060, P R China

Corresponding author: Chuanxing Li, MD. Email: lichuanh@mail.sysu.edu.cn

 

 

Citation: Maharjan R, Xiang ZW, Shi F, Wu KT, Li CX. Nasopharyngeal Carcinoma: Imaging Diagnosis and Recent Progress. J Nasopharyng Carcinoma, 2014, 1(1): e1. doi:10.15383/jnpc.1.

Competing interests: The authors have declared that no competing interests exist.

Conflict of interest: None.

Copyright: http://journalofnasopharyngealcarcinoma.org/Resource/image/20140307/20140307234733_0340.png2014 By the Editorial Department of Journal of Nasopharyngeal Carcinoma This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

 

 

Abstract: With continuous development of imaging techniques, medical imaging plays an important role in diagnosis of Nasopharyngeal Carcinoma (NPC) Computed tomography (CT) is the basic mean for diagnosis of NPC and has an advantage over diagnosis of those involving the skull base Magnetic resonance imaging(MRI) has an excellent soft tissue contrast resolution and it is superior to CT for detecting areas involving early primary focal invasion and retropharyngeal lymph node metastasis With positron emission tomography(PET) imaging alone, the anatomical localization is unclear but when combined with CT, it shows high sensitivity in the identification of primary tumor, lymph node metastasis ,distant metastasis and efficacy assessment In this article, we review the current imaging methods commonly used in clinical diagnosis of nasopharyngeal carcinoma and discuss the most recent advances

Keywords: Nasopharyngeal carcinoma; Imaging diagnosis; CT; MRI; PET/CT

 

 

 

Nasopharyngeal carcinoma is the most common head and neck cancer It is of epithelial origin and 90% are poorly differentiated squamous cell carcinoma followed by well-differentiated squamous cell carcinoma and undifferentiated carcinoma Due to its anatomy and pathology, radiotherapy is preferred and is the most effective means of treatment Local invasion and lymph node metastasis of nasopharyngeal carcinoma had higher incidence, early detection, early diagnosis, accurate staging and evaluation after treatment had been the key to improve the efficacy of treatment and prolong survival period[1] Moreover, CT, MRI and PET/CT play significant role in the diagnosis of NPC, its TNM staging and post treatment assessment as well as provides improved efficacy together in order to provide an important basis for further clinical treatment.

 

Computed Tomography

Nasopharyngeal carcinoma usually occurs in lateral nasopharyngeal recess Local soft tissue obviously thickens and forms a lobulated rim of soft tissue mass CT value about 35~45Hu, density is more or less uniform with adjacent muscle tissue Necrosis may be seen in a few places With the contrast scan, there is moderate enhancement CT has features of good density resolution and overlapping of unorganized images It can clearly show the nasopharynx and parapharyngeal and other deep soft tissue and is significant for qualitative diagnosis and positioning of nasopharyngeal carcinoma With the progression of NPC, the surrounding bone tissue is easily invaded Moreover, the biggest advantage of CT imaging is that the surrounding bony destruction by NPC can be clearly visualized on CT image Zheng et al [2] found that radiologists should pay attention to bony structures invaded by nasopharyngeal carcinoma on CT images In addition, CT scan is very quick and abundant information can be achieved ,it is also relatively cheaper and therefore is still an effective imaging method for diagnosis and follow-up of nasopharyngeal carcinoma.

 

New CT Techniques and diagnostic for Nasopharyngeal Carcinoma: Modern technologies of CT in nasopharyngeal carcinoma include perfusion imaging (CTP) and virtual endoscopy (CTVE),which are increasingly used in clinical diagnosis The technology of CTP utilizes perfusion parameters (such as :blood perfusion , blood volume and so on) to get an image which shows vascular characteristics and hemodynamic changes in nasopharyngeal lesion It can find more early recurrent nasopharyngeal carcinoma lesions than conventional CT Jin et al[3]found the technology of CTP can provide timely hemodynamic changes in the physiological and pathological situations and evaluate the efficacy of the treatment process, it can also further infer biological characteristics of the tumor and prognosis[4] Meanwhile, studies from Liu et al[5] also showed that multi-slice spiral CT can more clearly reflect the tumor blood flow, blood volume and other characteristics of tumor blood supply Moreover, they can be correlated with TNM staging of nasopharyngeal carcinoma Also with rapid development of spiral CT, its scan data can be used for reconstruction in variety of ways and image fusion as per clinical need Its benefits are that it can measure the size of tumor, determine the biological target for radiotherapy and can be used to further standardize radiation dose CT virtual endoscopy (CTVE) technology, also known as endovascular reconstruction techniques, applies a continuous spiral CT scans to adjust the threshold value of CT and organizational transparency, eliminate unwanted organization, and then show the change of lumen according to the navigation It is able to objectively display the surface and extent of the lesion and is good for guiding treatment and prognosis Zhao et al[6] found Multislice spiral CT virtual endoscopy(MSCTVE) and endoscopy had good correlation Song [7] also found that spiral CT image reconstruction was a reliable method to study the anatomy of facial nerve and other cranial nerve canals.

 

Magnetic Resonance Imaging

MRI shows a good soft tissue resolution Due to its multi-faceted, multi-parameter function of medical imaging and molecular characteristics, it is currently considered to be the most effective method for nasopharyngeal carcinoma It can clearly show the infiltration to surrounding structures of nasopharynx such as the parapharyngeal space, masticator space, pterygopalatine fossa,etc It can also detect the skull base and cranial nerve involvement as well as relatively smaller cervical and retropharyngeal lymph nodes In comparison to CT, MRI can cause staging changes about more 33 9% patients with NPC, 19 5% to adjust treatment strategy Sun[8] found that in X92 staging, MRI made 32 0% of the T stage change, 11 6% N staging change, 30 4% change in clinical staging According to the sixth edition of the UICC/AJCC staging, MRI makes 39 6% of the T stage change (36 0% upgrade, 3 6% downgrade); 9 2% N stage change(5 6% upgrade, 3 6% downgrade); 37 6% of the clinical stage change(33 6% upgrade, 4 0% downgrade) At the same time, MRI can detect the bone marrow infiltration by tumor before the local bone trabecula has been destroyed and distinguish fibrotic lesion and tumor recurrence after radiotherapy.

MRI Manifestations of Nasopharyngeal Carcinoma: NPC typically manifests the lesion of nasopharyngeal soft tissue, mainly originated in the pharyngeal recess, followed by nasopharyngeal wall and roof It causes local mucosal thickening or formation of small lumps and finally leads to toasymmetrical narrowing of nasopharynx Tumor tissue signal intensity is uniform, On T1W1 the tumor is isointense to the adjacent muscles, while on T2-weighted images, the tumor shows high signal intensity Gd-DT PA enhanced scan shows significant strengthening of the mass The tumor margins are partially visible and can intrude into pharyngonasal cavity by forming mass or the parapharyngeal space by submucosal growth Some sections may be infiltrative growth and form unclear boundaries with the surrounding structures Fat stripe disappears Most of the researches show[9] that MRI is the modality of choice for detecting local invasion of tumor With the growth of tumor, it spreads anterolaterally or posteriorly invading the sorrounding tissue Even the meninges behind the invaded structures may be seen thickened or formation of lumps NPC can also be dissected along the adjacent channels (such as the carotid sheath, oval foramen, etc) into invading the brain, it results in local thickening of the meninges or the cavernous sinus and forming lumps.

In addition, submucosal nasopharyngeal carcinoma mainly spreads from nasopharyngeal epithelial submucosal growth, forming deep submucosal mass The signal intensity is similar to that of typical naospharyngeal carcinoma but nasopharyngeal mucosa is still intact and smooth, T2W1 shows continuous hyperintense linear shadow Most of the biopsies were negative, only by taking deep biopsy of the submucosal tumor as displayed in MRI images, diagnosis is possible.

 

New MRI Techniques for Nasopharyngeal Carcinoma: Modern technologies of MRI include diffusion-weighted imaging(DWI), magnetic resonance spectroscopic imaging(MRS), magnetic resonance perfusion imaging (PWI )and diffusion tensor imaging(DTI) Diffusion-weighted imaging can sensitively detect nasopharyngeal primary tumor and metastatic lymph nodes[10] and also through the apparent diffusion coefficient (ADC) value differentiate between the nasopharyngeal lymphoma and cervical lymphoma Fong et al [11] reported that DWI can be used to differentiate between nasopharyngeal carcinoma and nasopharyngeal lymphoma ADC value of nasopharyngeal lymphoma is about (0.75±0.19)× 10-3mm2/s while that of NPC is approximately (0.98±0.16)× 10-3mm2/s ADC value for nasopharygeal lymphoma is lower than that of NPC Ozgen et al [12]found that in NPC skull base invasion, the ADC value of skull base was lower than that of osteomyelitis ADC value was about (0.74 ± 0.18)×10-3mm2/s in NPC invasion while (1.26±0.19)×10-3mm2/s in osteomyelitis Magnetic resonance spectroscopic imaging, by measuring the content of metabolites between the tumor and normal tissues , can evaluate the content of metabolites changes in the tumor tissue[13], it mainly detects choline(Cho), creatinine (Cr), lactate (Lac) and N-acetyl asparate(NAA) among other metabolites in the tissue Jansen et al[14] found that 1 H MRS combined with PET can better predict short-term efficacy of NPC Li et all [15]also proved that the Cho was increasing, the NAA was declining and the rate of Cho/NAA was also increasing 3 weeks before radiotherapy The peak value of Cho of damaged brain tissue was higher than that of normal brain tissue, peak NAA value was less and with treatment the peak values gradually returned to normal Thus, there is a significant value of MRS assessment for evaluation of curative effect of NPC, early detection of recurrenance and assessment of temporal lobe damage due to radiation Magnetic resonance perfusion imaging can distinguish between the tumor tissue and fibrosed tissue after radiotherapy and can be used for the detection of recurrent lesions of NPC The studies from Quon [16] showed that the residual tumor area showed a high perfusion in PWI but noted that to confirm whether the high perfusion area is due to tumor antiogenesis or not needs further investigations Magnetic resonance diffusion tensor imaging can be used to assess radiation damage to the brain tissue as well as to monitor the changes of brain during the curative process Early changes after radiotherapy can be displayed with DTI which is not possible with conventional MRI[17], therefore, it can prevent or delay radiation induced brain tissue damage and provide more imaging evidences for clinical early intervention treatment In conclusion, advances in MRI technology with its unique advantages to NPC imaging has opened a new chapter in its diagnostic imaging In clinical practice, every new imaging technique plays a different role and can also be used in together according to the requirment, it can complement each other and thus improve comprehensive diagnostic capabilities of NPC

Advances in TNM Staging of Nasopharyngeal Carcinoma: In 2009, a collaborative project of UICC and AJCC formed 7th edition of TNM classification(Table 1) by modifying the 6th edition formed in 2003 In compare to 6th edition, the 7th edition of UICC/AJCC has staged that the oropharynx and nasal involvement down to T1 and the retropharyngeal lymph nodes is regarded as N1 Moreover, MRI for primary tumor invasion , skull base involvement as well as retropharyngeal lymph nodes is preferred than CT.

 

 

Table 1 Seventh edition of UICC staging system for nasopharyngeal carcinoma

Classifications UICC (2009) staging system

T1 Nasopharynx, oropharynx or nasal cavity without parapharyngeal extension

T2 Parapharyngeal extension

T3 Bony structures of skull base and/or paranasal sinuses

T4 Intracranial,cranial nerves, hypopharynx, orbit,

Infratemporal fossa/masticator space

N1 Unilateral cervical, unilateral or bilateral retropharyngeal lymph nodes, above supraclavicular fossa; < 6 cm

N2 Bilateral cervical above supraclavicular fossa;< 6 cm

N3 N3a > 6 cm

N3b Supraclavicular fossa

 

 

Primary tumor staging of nasopharyngeal carcinoma: Primary tumor staging of nasopharyngeal carcinoma (T stage), according to the size of the primary tumor nasopharyngeal carcinoma and its surrounding tissue invasions, is divided into 4 stages(Table 1) Assessment of primary nasopharyngeal tumors and its surrounding tissue structure is the most important factor for treatment and prognosis of NPC Parapharyngeal space from the base of the skull to the crescent-shaped hyoid bone mainly contains fat tissue, on MRI it is usually characterized by high signal intensity TNM classification of parapharyngeal space involved is defined as infiltration posterolaterally beyond the fascia of nasopharyngeal skull base On T1W1 and T2W2 imaging, pharyngobasilar fascia is expressed as hypointense linear signal, early involvement is expressed as interrupted line It can be taken to identify tumors confined to parapharyneal cavity, parapharyngeal space invasion and pharyngeal lymph nodes after fusion 7th edition of UICC/AJCC staging defined parapharyngeal involvement which contains masticator space as T2, Teo P et al [18] found that parapharyngeal involvement was associated with distant metastasis and prognosis in NPC patients Masticator space is located outside the parapharyngeal space, containing palate venous plexus, mandibular nerve and the muscles of mastication, the muscles mainly include the temporalis muscle, masseter, medial and lateral pterygoid muscles 7th edition of UICC/AJCC staging defined invasion of medial pterygoid muscles in masticator space as T4 Studies by Chong VF et al[19] have shown that the specific imaging findings that will directly affect the stage and treatment of NPC Lateral pterygoid muscle involvement means neurovascular tissue within the gap has been involved The studies from Chen YB [20]also showed that 69 14% medial pterygoid muscle involvement was associated with characteristics of nerve involvement in T4 NPC MRI has significant advantage to show tumor involving cranial nerve lesions over CT On MRI, the circular structures or disappearance of fat around the patent foramen can serve as a reliable sign of nervous around early infiltration Early detection of cranial nerve involvement is possible with MRI Studies from Cheng SH et al[21] showed that MRI diagnosis of cranial nerve involvement enables more patients with T-stage upgrade NPC with cranial nerve involvement usually indicates poor prognosis ,the survival and control rates in these patients were significantly reduced[22] It has been reported [23] that among the T3, T4 NPC patients, the 3 year overall survival rate of no distant metastasis was significantly higher than those with cranial nerve invasion in MRI In 3 year overall survival group with cranial nerve palsy, there was no significant difference in survival in patients without distant metastasis, local recurrence free survival and the group without cranial nerve palsy.

 

Lymph Nodes Staging: According to the 7th edition of UICC/AJCC criteria

(Table 1), unilateral retropharyngeal lymph nodes are classified as N1, bilateral cervical lymph nodes metastases as N2 and for N2 or N3, the main difference lies in the size of lymph nodes and site involved N staging of NPC lymph node metastasis depends on the evaluation of retropharyngeal and cervical lymph node metastasis which acts as the key factor affecting the clinical staging, treatment planning and prognosis NPC firstly metastasized to the retropharyngeal lymph nodes, MRI is superior to CT for detecting retropharyngeal lymph nodes<4mm and can distinguish from primary tumor site The studies from King and Lam[24,25] showed that lateral retropharyngeal lymph nodes which the minimum of diameter was 5mm can be considered as metastases and medially any visible lymph node be considered as malignant When retropharyngeal or cervical lymph node showed necrosis or extracapsular spread, it would be malignant regardless of the size of lymph node.

 

Positrone Mission Tomography-computed Tomograph PET/CT Manifestation of NPC: The characteristics of PET/CT imaging of NPC show irregular or spherical shape of primary nasopharyngeal tumor The soft tissue mass of NPC has specific characteristics with metabolic sharp edges, invasion and metastasis It can roughly divided into two types; mucosal and submucosal invasive type Mucosal type are small, mostly unilateral, bulky shadow and cord like shadow (cross-section), less dioactive concentration and indistinct boundaries Oval mass shadow is common in submucosal type, mostly unilateral Bilateral invasions are connected together with multiple cervical lymph node metastases forming "pea shaped" Radioactivity concentration is significantly increased It can clearly show the primary tumor location, size, shape, relations with the surrounding tissue and cancer tissue metabolism.

 

TMN staging: NPC patients are prone to lymph node metastasis and distant metastasis The most common metastasis is to the meditational lymph nodes, which is followed by lung, liver and finally bone metastasis Distant metastasis is an important indicator for prognosis of NPC but only about 1/6 of the patients are diagnosed with distant metastasis on examination Meta-analysis by Chang MC et al[26] found that the good diagnostic performance of the whole-body FDG-PET or PET/CT in M staging of NPC Researches from Liu et al[27] suggested that PET/CT carried a higher diagnostic accuracy in the depiction of distant metastases of cervical lymph node metastases than enhanced CT and MRI It was also more sensitive and accurate than enhance CT and MRI for diagnosing residual or recurrent NPC In addition, PET/CT can detect metastatic lymph nodes of ≤10mm A study from Antoch et al[28] compared MRI and PET/CT findings in 98 cases of malignant tumors in which accuracy was 79% and 93% respectively in N staging.

 

Radiotherapy and Efficacy Assessment:

Currently, due to the special nature of nasopharyngeal anatomy and pathology, radiotherapy is preferred and is the most effective means of treatment PET/CT has an irreplaceable role before the radiotherapy of nasopharyngeal lesion, it can confirm the size and scope of lesion, make radiation treatment planning,and provide the basis for clinical treatment and prevention of further complications after radiotherapy provide the basis Zhuang etc [29]found PET/CT can help determine the tumor target volume and clinical target volume, it can also devote to build appropriate programs and three-dimensional radiotherapy program Meantime, Shankar LK [30]also thought that PET/CT is the first step before radiotherapy planning.

The partial residual tumor and recurrence after comprehensive treatment of NPC is very common ,the suitable evaluation of the local and systemic conditions of the patients which in turn is very important for timely and effective treatment to improve the patient life quality and prolong survival The study by Ng SH et al[31] suggested that it was difficult to accurately distinguish between the residual/ recurrence of tumor from radiotherapy fibrosis, edema and scar by CT, MRI Analysis of 21 studies done between 1990 to 2007 by Liu T et all[32] showed that PET had an upper hand over CT, MRI in diagnosis of local recurrence, moreover, PET which was combined with CT would be the most perfect Thus, PET/CT has a higher sensitivity and specificity in early detection of nasopharyngeal tumor recurrence after radiotherapy[33,34] TSA IM H et al[35,36] also found that, in the follow-up of patients after radiotherapy, those patients on MRI suggested residue and recurrence of NPC, the sensitivity of undergoing PET/CT scan was 90% ~100%, specificity was 88 9%~100% and accuracy was 85 7%~97%, the result was that PET/CT should be better than MRI in early detection of nasopharyngeal tumor residue and recurrence after radiotherapy Therefore, PET/CT can be used effectively to compensate the limitations of CT and MRI in detection of residual and recurrent tumor

 

Summary

At present, the imaging methods for clinical diagnosis of NPC include CT, MRI and PET/CT and they do have their own characteristics Radiological diagnosis of NPC should be done by a combination of CT,MRI and PET/CT for comprehensive analysis and estimation Since different forms of imaging are complementary to each other, only through multi-mode imaging can we get broader and comprehensive information MRI is superior in depiction and delineation of local invasion of primary tumor, when combined with diagnostic characteristics of distant metastasis on PET/CT ,it will be the best clinical strategy to guide diagnosis and cure However, for early diagnosis, relapsing tumor after treatment and recessive forms of metastases still remains difficult and requires more clinical trial data analysis and research

 

References

1 Chung N N, Ting L L, Hsu WC, et al Impact of magnetic resonance imaging versus CT on nasopharyngeal carcinoma: primary tumor target delineation for radiotherapy [J] Head Neck ,2004, 26( 3) : 241- 246.

2 Zheng GL, Zeng QX, Wu PH, et al Computed tomography in the management of nasopharyngeal carcinoma Clini Radiol 1989; 40: 25.

3 Su D, Jin G, Xie D, et al Identification of local recurrence and radiofibrosis by computed tomography perfusion on nasopharyngeal carcinoma after radiotherphyJ]. Can Assoc Radiol J, 2010, 61 (5): 265-270.

4 Jin G, Su D, Liu L, et al The accuracy of computed tomographicperfusion in detecting recurrent nasopharyngeal carcinoma after radiation therapy J J Comput Assist Tomogr, 2011,35(1):26-30.

5 Liu YL, Chen X, Chen J, et al Nasopharyngeal carcinoma CT perfusion imaging and their correlation in biology study Chin J Radiol 2007;41( 9) : 907-9111.

6 Zhao DL, Zhang ZR, Liu BL, et al The diagnostic value of nasopharyngeal carcinoma in the multislice spiral CT virtual endoscopy [J] Journal of China Clinic Medical Imaging , 2007, 18( 8) : 563-5651.

7 Song YG, Liu JH, Zhao GM, et al Curved planar reform ation and anatomical study Journal of Practical Radiology, 2006, 22( 12) :1441-51.

8 Sun Y, Mao YP, Ma J, et al The role of MRI in nasopharyngeal cancer stagingJ Chinese Journal of Cancer 2007;26(2):158-63.

9 Cheng YZ, Hu CS, Zhou ZR, et al The bone of the skull base invasion of nasopharyngeal carcinoma (NPC) CT and MRI contrast detection [J] China Oncology 2005; 15(2) :167-8.

10 Takahara T, Imai Y, Yamashita T, et al Diffusion weighted whole body imaging with background body signal suppression (DWIBS): technical improvement using free breathing, STIR and high resolution 3D display Radiat Med 2004;22(4):275-82.

11 Fong D, Bhatia KS, Yeung D, et al Diagnostic accuracy of diffusion-weighted MR imaging for nasopharyngeal carcinoma, head and neck lymphoma and squamous cell carcinoma at the primary site Oral Oncol 2010;46:603-6.

12 Ozgen B, Oguz KK, Cila A Diffusion MR imaging features of skull base osteomyelitis compared with skull base malignancy[J] AJNR Am J Neuroradiol 2011;32:179-84.

13 Chawla S, Kim S, Loevner LA, et al Proton and phosphorous MR spectroscopy in squamous cell carcinomas of the head and neck Acad Radiol 2009;16:1366-72.

14.Jansen JF, Sch der H, Lee NY. Tumor metabolism and perfusion in head and neck squamous cell carcinoma : pretreatment multimodality imaging with 1H magnetic resonance spectroscopy,dynamic contrast-enhanced MRI, and [18F]FDG-PET [J]. Int J Radiat Oncol Biol Phys 2012;1;82:299-307.

15 Li H, Li JP, Lin CG, et al An experimental study on acute brain radiation injury: Dynamic changes in proton magnetic resonance spectroscopy and the correlation with histopathology Eur [J] Radiol 2012;81(11):3496-503.

16 Quon H, Brizel DM Predictive and prognostic role of functional imaging of head and neck squamous cell carcinomas Semin Radiat Oncol 2012;22(3):220-32.

17 Chapman CH, Nagesh V, Sundgren PC Diffusion tensor imaging of normal-appearing white matter as biomarker for radiation-induced late delayed cognitive decline[J] Int J Radiat Oncol Biol Phys 2012;82:2033-40.

18 Teo P, Lee WY, Yu P The prognostic significance of parapharyngeal tumor involvement in nasopharyngeal carcinoma Radio therOncol 1996;39:209-21.

19 Chong VF, Mukherji SK, Ng SH, et al Nasopharyngeal carcinoma :review of how imaging affects staging [J] Comput Assist Tomogr 1999;23(6):984-993.

20 Chen YB, Fang YH, Chen Y, et al MRI study on the relationship between the invasion patterns and staging of nasopharyngeal carcinoma. Chinese Journal of Radiology 2010;44(10):1024-9.

21 CHENG SH, TSAI SY, HORNG CF, et al A prognostic scoring system for locoregional control in nasopharyngeal carcinoma following conformal radiotherapyJ Int J Radiat Oncol Biol Phys 2006;66:992-1003.

22 Galloway T[J], Morris CG, Mancuso AA, et al Impact of radiographic findings on prognosis for skin carcinoma with clinical perineural invasion Cancer 2005;103(6): 1254-7.

23 Liu L, Liang S, Li L, et al Prognostic impact of magnetic resonnce I maging-detected cranial nerve involvement in nasopharyngeal carcinoma Cancer 2009;115:1995-2003.

24 King AD, Ahuja AT, Leung SF, et al Neck node metastases from nasopharyngeal carcinomaMR imaging of patterns of disease[J] Head Neck 2000;22(3):275-81.

25 Lam WW, Chan YL, Leung SF, et al Retropharyngeal lymphadenophy in nasopharyngeal carcinoma[J] Head Neck 1997;19(3):76-181.

26 ChangMC,ChenJH,LiangJA,etal Accuracyof whole-body FDG-PET and FDG-PET/CT in M staging of nasopharyngeal carcinoma: a systematic review and meta-analysis Eur [J] Radiol 2013 Feb;82(2):366-73.

27 Liu T, Xu W, Yan WL, et al FDG-PET,,CT,,MRI for diagnosis of local residual or recurrent nasopharyngeal carcinoma,,which one is the best? A systematic review [J] Radiother Oncol 2007;85(3): 327-35.

28 ANTOCH G, VOGT FM, FREUDENBERG LS, et al Wholebody dual-modality PET/CT and whole-body MRI for tumor staging in oncology[J] JAMA 2003; 290(24): 3199-3206.

29 Zhuang H, Kumar R, Mandel S, et al Investigationofthyroid,,head and neck cancers with PET Radiol Clin North Am,2004,42(6):1101-1111.

30 shankar LK, Hoffman JM, Bacharach S, et al Consensus reeommendations for the use of 18F-FDG PET as an indieator of therapeutic response in Patients in National Cancer Institute Thals [J] Nuel Med, 2006;47(6):1059-1066.

31 Ng SH, Liu HM, Ko SF, et al Posttreatment imaging of the nascopharynx Eur [J] Radiol 2002;44(2):82-95.

32 LIU T, XU W, YAN WL FDG-PET, CT, MRI for diagnosis of local residual or recurrent nasopharyngea carcinoma, which one is the best? A systematic review[J] Radiother Oncol 2007;85(3): 327-35.

33 Ng SH, Joseph CT, Chan SC, et al Clinical usefulness of 18FFDG PET in nasopharyngeal carcinoma patients with questionable MRI findings for recurrence [J] Nucl Med,2004,45(10):1669-76.

34 Yen RF, Hung RL, Pan MH, et al 18-fluoro-2-deoxyglucose positron emission tomography in detecting residual/recurrent nasopharyngeal carcinomas and comparison with magnetic resonance imaging Cancer 2003;98(2):283-287.

35 TSA IM H, SH IAU Y C, KAO CH, et al Detection of recurrent nasophryngeal carcinom asw ith positron em iss ion tomography using 18- fluoro- 2-deoxyglucose in pat ien tsw ith indeterm inatem agnetic reson ance im ag ing find ings after rad iotherapy[J] Cancer Res Clin Oncol 2002;128(5):279-82.

36 Kao CH, Chang Hanglaisp Detection of recurrent or persistent nasopharyngeal carcinomas after radio therapy with 18-fluoro-2-deoxyglu cose positron emission tomography and comparison with computed tomography Clin Oncol 1998;16(11):3550-5.

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