Objective To discuss the application value of DWI and ADC on predicting therapeutic effect of radiotherapy treatment in NPC. Methods Twenty four local recurrent cases and 38 non-recurrent cases after radiotherapy treatment in NPC were reviewed. MRI and DWI-MRI were performed at pre-radiotherapy and 3, 6, 12 months after treatment, the ADC values of the lesions were analyzed by SPSS 18.0 statistical software. ROC curves based on the ADC values were measured in 3, 6, 12 months after treatment plotted to analyze the threshold ADC value for confirming recurrence. Results The recurrent group and newly diagnosed group showed significantly high signal on DWI, while the non-recurrent group acquired low or mixed signal. The ADC values of the primary tumor in the recurrent group and the non-recurrent group were (0.709 ± 0.078) × 10-3 and (0.693 ± 0.089) × 10-3mm2/s, respectively, t=-0.717,P>0.05, respectively.The ADC values of the primary and recurrent tumor in the recurrent group were (0.730± 0.068) × 10-3mm2/s and (0.709 ± 0.078) × 10-3mm2/s, t=-1.000,P>0.05 , respectively.There were statistical differences between the recurrent group and the non-recurrent group for ADC in 3, 6, 12 months after treatment:(1.128 ± 0.179) × 10-3 and (1.358 ± 0.145) × 10-3mm2/s, t=5.567,P<0.01;(1.164 ± 0.174) and (1.450 ± 0.102) × 10-3mm2/s, t=7.310,P<0.01;(1.107 ± 0.180) × 10-3 and (1.584 ± 0.125) × 10-3mm2/s, t=11.189,P<0.01;respectively. Take 1.29 × 10-3 mm2/s,1.32 × 10-3mm2/s,1.37 × 10-3mm2/s respectively in 3, 6, 12months after treatment as the diagnostic threshold to predict tumor recurrence. The sensitive , specificity, and accuracy were (83.3%, 73.7%, 77.4%), (83.3%, 89.5%, 87.1%), (100.0%, 94.7%, 96.3%).Conclusions Both DWI and ADC value are important for diagnosing and predicting recurrent NPC after radiotherapy treatment, DWI and ADC can be used to regular follow-up after radiotherapy, to further improve the rate of early diagnosis of recurrent NPC.

Objective To prospectively evaluate the value of diffusion-weighted imaging with background signal suppression (DWIBS) in the detection and diagnoses of metastatic cervical lymph nodes. Methods Twenty patients with head and neck squamous cell carcinomas underwent conventional MRI and DWIBS. The ADC values were measured and compared between metastatic and benign lymph nodes. The abilities of DWIBS and conventional MRI in the evaluation of metastatic cervical lymph nodes were compared. Results Conventional MRI demonstrated 101 lymph nodes, in which 58 were diagnosed as metastatic nodes. When MRI criteria were used for discrimination between metastatic and benign nodes, the obtained sensitivity, specificity, accuracy, positive and negative predictive value were 78% (47/60), 81%(44/54), 80% (91/114), 82% (47/57) and 77% (44/57), respectively. The mean ADC values of metastatic nodes (n =60) and benign nodes (n =54) were (0.945 ±0.122) × 10-3 mm2/s and (1. 210 ±0. 151 ) × 10-3 mm2/s ( t = - 10. 354 ,P ＜0. 01 ). When an ADC value of 1. 090 × 10 -3 mm2/s was used as the threshold for discrimination between metastatic and benign nodes, the obtained sensitivity, specificity,accuracy, positive and negative predictive value were 88% (53/60), 80% (43/54), 84% (96/114), 83%(53/64) and 86% (43/50), respectively. Conclusion DWIBS is helpful in diagnosing metastatic cervical lymph nodes of head and neck squamous cell carcinoma, and is superior to conventional MRI in their detection.

Objective To study the imaging features of Kimura disease to improve diagnostic ability prior to surgery.Methods The clinical manifestations and CT and MR findings of 11 patients with histologically confirmed Kimura disease were retrospectively analyzed.All 11 tumors originated from (or involved)the parotid region in 7 cases, the maxillofacial region in 2 cases, the palate in one case and the groin in one case.Clinically, the lesions showed asymptomatic tumors with the mean clinical course over 2 years.The increase of cosinophilic granulocyte was found in all 11 cases.Results On CT and MRI,5 patients were single masses and others were muhi-nodular masses.The smallest lesion was 6 mm×3 mm,and the largest lesion was 60 mm × 34 mm.The lesions were almost ill-defined in the subcutaneous tissue,especially 10 locating underlying superficialfascia in head and neck.On CT,the lesions showed homogeneous hypodense to the muscle in 9 patients.The lesions appeared isointeuse signal or slightly hypointense on MR T1WI and slightly hyperinteuse on T2WI in 3 patients.All lesions revealed moderate or marked, and homogeneous or inhomngeneous enhancement.Regional lymph nodes (eight cases in the maxillofacial region and one in the groin) enlarged without necrosis and fusion, and with marked enhancement.Conclusion The clinical and imaging findings of Kimura disease have some characteristics, the diagnosis can be made combined with the laboratory examination.

Objective To evaluate the signal changes of the skull base after salvage surgury via endoscopic transnasal approach for local recurrent nasopharyngeal carcinoma.Methods Twenty patients with nasopharyngeal carcinoma after radiation failure underwent nasophargeryngectomy via an endoscopic transnasal approach were selected from April 2006 to December 2011,including 16 males and 4 females with 31 to 67 years old.Each patient had previously received irradiation and experienced recurrence after 8 to 83 months of completed irradiation.All patients underwent MRI no more than 2 weeks before the salvage surgery and were subjected to repeat MRI scans 2 weeks,3 months,6 months later and semi-annually thereafter,with the follow-up time of 6 to 45 months(median 18 months).A two-sided Chi-square test was used to compare the signal changes and the tendency of changes on all presurgical and postsurgical MR images.Results The MRI signal changes were detected at 92 sites of skull-base between 2 weeks and 3 months after the surgery,which was hypointense on T1 WI with moderate to marked contrast enhancement.In the follow-up period,the signal abnormalities at 36 sites of skull base had resolved or restored to the normal,and 34 sites remained stable,while in 22 sites,the MR signal changes became more obvious.The skull base bones adjacent to the region of the resection were more likely to show signal changes than nonadjacent areas (72 vs.20,x2 =33.128,P ＜0.01).The signal changes were more common on the ipsilateral skull base to the recurrent tumor in contrast to the contralateral skull base (68 vs 24,x2 =21.182,P ＜ 0.01).Conclusions The skull base signal changes after salvage surgury via endoscopic transnasal approach for local recurrent nasopharyngeal carcinoma,and it occurs in specific location.Most of sites tend to resolve or be stable at the follow up.

Objective To characterize the features of Nasopharyngeal non-Hodgkin's lymphoma (NHL) on MR imaging and find the main points to differentiate it from the other nasopharyngeal tumors.Methods The MR images of 41 patients with pathologically and immunohistochemically proven nasopharyngeal NHLs were reviewed retrospectively. Images were assessed by the size, invasive extent,signal intensity of primary nasopharyngeal tumor, and the distribution of cervical lymphadenopethy. The difference of regional tissues invasion and cervical lymphadenopathy distribution between the patients with B-cell NHLs and the patients with T-cell or NK/T-cell NHLs were analyzed by Pearson's Chi-Square test or Fisher's exact test Results Of the 41 patients, 26 patients had mature B-cell lymphoma, two patients with mature T-cell Iymphoma, and thirteen patients showed Nature killer/T-cell lymphoma in nasopharynx. MRI revealed that NHLs of nasopharynx can be showed as thickening of nasopharyngeal mucosa and (or) lumps in nasopharynx, which were slightly hyper-intensity on T2-weighted images, and intermediate signal intensity (similar to muscle) on T1 -weighted images, with mild or moderated enhancement following contrast medium administration. Twenty four cases had symmetrical disease of all walls of nasopharynx, and 17 cases had unsymmetrical tumor. Of all cases, 5 cases had superficial ulcerations, 9 cases had exceed nasoharynx invasion spreads superficially along the mucosa, 23 cases had invasion of lingual and (or) palatine tonsils,20 cases showed invasion of parapharygeal muscles, 12 cases suffered from skull base bone infiltration,25 cases had retropaharyngeal lymphadenopathy, and 27 cases had cervical lymhadenopathy. Patient with nasopharyngeal Nature killer/T-cell lymphoma had a higher incidence of exceed nasopharynx invasion,parapharyngeal structures invasion, and superficial ulcerations (the cases were 8, 11, 4 in patient with T-cell or N K/T-cell lymphoma, and 4, 10, 1 in patients with B-cell lymphoma, respectively). Patients with nasopharyngeal B-cell lymphoma had a higher incidence of inasion of lingual and (or) palatine tonsils.Conclusions Nasopharyngeal NHL is a homogeneous tumor that tends to diffusely involve all walls of the nasopharynx and spread in an exophytic fashion to fill the airway, rather than infiltrating into the deep tissues. Different pathological types of nasopharyngeal NHLs have some different appearance on MRI between each other. A large tumor in nasopharynx that fills the nasopharynx cavity, with no or minimal invasion into deep structures, but with invasion extend down into the lingual and(or)palatine tonsils, may suggest the diagnosis of nasopharyneal NHL.

Objective To explore the incidence, clinical characteristics, and prognosis of radiation encephalopathy (REP) in nasopharyngeal carcinoma (NPC) patients after intensity-modulated radiotherapy (IMRT). Methods 870 NPC patients confirmed pathologically and without distant metastasis received radical IMRT,570 of which received chemotherapy simultaneously,and followed up for 6 -104 months (with a median of 40 months),undergoing magnetic resonance imaging (MRI) once every 3 months within the first 3 years after treatment and then once every year.The clinical manifestations were observed.In 29 of these 42 patients diagnosed as with REP,the dose distributions of REP lesions were evaluated.Results 4.83％ of the NPC patients (42/870) were diagnosed as with REP.There were 39 cases with pure temporal lesion (bilateral in 6 cases),with a median latency period of 30 months (6 -56 months),2 cases with pure cerebral stem lesion both with a latency period of 14 months,and one case with lesions in temporal lobe and cerebral stem with the latency period of 18 months.REP was not observed in the stage T1-2 patients.The incidence rate of REP was 3.09％ for the stage T3 patients and 14.35％ for the stage T4 patients.Twenty-two patients underwent following-up MRI after initial diagnosis of REP.After medication or surgical treatment the conditions became better or stable in the most cases. Dosimetric analysis of 32 injured temporal lobes in 29 patients found that the maximal dose was in the contrastenhanced lesions in 27 injured temporal lobes and in edema regions in 5 injured temporal lobes.For each patient,the maximal dose in the normal temporal lobe was lower than that in the injured temporal lobe.In the same patient,the maximal dose,minimal dose,and mean dose of contrast-enhanced lesions were all higher than those in the edema region.Conclusions The incidence of REP after IMRT is high,especially in local advanced NPC patients. Active treatment stabilizes or improves the REP condition. REP is positively correlated with dose of irradiation to brain tissue.

Objective To evaluate the value of MR spectroscopy (MRS) in the differential diagnosis between recurrence and radiation encephalopathy after radiotherapy for nasopharyngeal carcinoma (NPC). Methods Muhi-voxel proton MRS was performed on 50 patients with NPC, who were suspected of intracalvarium tumor recurrence or radiation encephalopathy after radiotherapy by conventional MRI,including 44 males and 6 females. Among the 50 patients, 26 cases were finally diagnosised as basicranial tumor recurrence and 24 cases as radiation encephalopathy by clinical and MRI follow-up. The following metabolites, such as Cho, NAA, Cr, lactate and lipid, were analyzed comparatively between basicranial tumor recurrence and radiation encephalopathy(RE), and between the lesions and the relative normal brain tissue. Wilcoxon's rank sum test was used to analyze the data. Results The median of Cho/Cr, Cho/NAA,LI/Cr in tumor recurrence group were 2. 22, 2. 13, and 1.77, respectively, and 1.40, 1.31, and 0. 57,respectively, in RE group. The difference of Cho/Cr, Cho/NAA, and LL/Cr between the two groups were statistically significant (P < 0. 01). Those in tumor recurrence group were higher than in RE group. The median of Cho, Cr, NAA in tumor recurrence group and in RE group were 3366. 00, 1023.00, 1930. 00 and 2469.50, 1864.50, 1734.00. There were no significant difference of Cho, Cr, and NAA between the two groups (P > 0. 05). In the 14 cases whose normal brain tissue were compared with the recurrent tumor tissue in tumor recurrence group, the median of Cr, NAA, LL, Cho/Cr, Cho/NAA, LL/Cr of recurrent tumor tissue and normal brain tissue were 1023.00, 1930.00, 2090.00, 3.76, 2. 13, 3.39 and 2370.00, 3012.00, 1680.00, 1.64, 1.17, 0.75,The difference of Cr, NAA, LL, Cho/Cr, Cho/NAA, LL/Cr between the normal tissue and recurrent tumor tissue were significant (P <0.05). LL, Cho/Cr, Cho/NAA, LL/Cr of recurrent tumors were higher than those of the normal brain tissue,while NAA and Cr of recurrent tumors were lower than those of the normal brain tissue. In the 12 cases whose normal brain tissue were compared with the RE tissue in RE group, the median of Cho, Cr, NAA, LL, Cho/Cr, IX,/Cr of RE tissue and normal brain tissue were 390.00, 217.50, 427.50, 39.00, 1.30, 0.40 and 680.00, 360.00, 610.00, 30.00, 1.54, 0. 09. The difference of above-mentioned parameters between RE tissue and normal tissue were significant. Cho, Cr, NAA, Cho/Cr of RE were lower than those of normal tissue (P <0. 05) ,while LL and LL/Cr of RE were higher than those of normal tissue (P < 0. 05). Conclusion The changes of the metabolites in recurrent lesions and RE lesions were different on MRS. Parameters such as Cho/Cr, Cho/NAA and LL/Cr, which were higher in recurrent lesions than those of RE, were valuable for the differential diagnosis between basicranial tumor recurrence and radiation encephalopathy after radiotherapy for NPC.

Objective To summarize the CT and MRI features of radiation-induced sarcoma (RIS) after radiotherapy in patients with nasopharyngeal carcinoma (NPC).Methods From January 1997 to October 2012,a total of 73 NPC patients with RIS after radiotherapy were confirmed by pathology.The clinical data and imaging findings (CT and MRI findings) were retrospectively reviewed.Of the 73 patients,43 underwent CT examination,24 underwent MRI,and the remaining 6 underwent both CT and MRI scans.Results Fibrosarcoma [45.3％ (33/73)] was the most frequently histologic type,followed by osteosarcoma[31.5％ (23/73)] and malignant fibrous histiocytoma [9.6％ (7/73)].The top three common sites were maxillary sinus [26.7％ (20/73)],followed by the neck soft tissue [17.8％ (13/73)] and mandible[13.7％ (10/73)].The main characteristics of the RIS on CT and MRI were soft tissue masses[78.1％ (57/73)] with an irregular shape and ill-defined margin,or rounded masses with welldefined margin [21.9％ (16/73)].CT of 49 patients showed masses with isodensity or mixed density on precontrast CT.MRI of 30 patients showed lesions with isointensity signal on T1WI and intermediate signal intensity on T2WI.On post-contrast images,65.8％ (48/73) tumors showed markedly homogeneous or inhomogeneous enhancement,23.2％ (17/73) lesions showed moderate enhancement,and 11.0％ (8/73) masses showed mild enhancement.Among the 23 patients with radiation-induced osteosarcomas,78.3％ (18/23) presented tumor bone formation.Conclusions RIS has a characteristic imaging features.Clinical history,tumor sites and serial imaging follow-up are necessary for early detection of RIS in patients with NPC.

Objective To explore the reasonable radiologic nodal size criterion of retropharyngeal lymph node (RLN) metastasis in patients with nasopharyngeal cancer (NPC).Methods Imaging and clinical data of 817 NPC patients were analyzed retrospectively.The patients with RLN metastasis were classified into two groups according to the nodal size of 5 mm or 6 mm as standard in diagnosis.Overall survival (OS),distant metastasis-free survival (DMFS) and the local-relapse-free survival (LRFS) were assessed between the two groups taking 5 mm or 6 mm as standard in diagnosis of RLN.Results No significant difference was found for OS,DMFS,LRFS between nodal size ＜5 mm group and ≥5 mm group.Difference of OS (P＜0.001),DMFS (P=0.001) were significant statistical and difference of LRFS (P=0.380) had no significant statistical between nodal size ＜6 mm group and ≥6 mm group.OS,DMFS,LRFS were not an independent prognostic factor for NPC.Conclusion Using the minimal axial diameter of 6 mm as the nodal size criterion in diagosis of RLN metastasis in patients with NPC may be more reasonable.

Objective To compare the diagnostic efficacy of bone scintigraphy and MRI on vertebral metastases in patients with nasopharyngeal cancer (NPC). Methods Forty-seven patients of NPC and clinically confirmed metastatic disease in spine underwent bone scintigraphy and MR examination. The number of involved vertebri diagnosed with two methods were calculated and compared retrospectively. Results A total of 187 vertebral metastases were found in 47 patients, among which 153 (81.82%) were detected with bone scintigarphy and 182 (97.33%) were diagnosed with MRI (χ~2＝23.758, P＝0.000). Conclusion Compared with bone scintigraphy, MRI is superior in detecting vertebral metastases from NPC, and can be used as the first choice for the early diagnosis of spinal metastases from NPC.