Magnetic Resonance Imaging Findings of Temporal Lobe Radiation Encephalopathy in Nasopharyngeal Carcinoma

Objective： To observe the magnetic resonance imaging （MRI） morphological features of radiation encephalopathy （REP） in nasopharyngeal carcinoma （NPC） and investigate their diagnostic value. Methods： The MRI data of 160 lesions from 104 NPC patients with the diagnosis of temporal lobe REP were retrospectively analyzed. The MRI was performed after radiation therapy of NPC with an interval ranged from 8 months to 13 years. The imaging sequences included T1-weighted imaging and T2-weighted imaging. Additionally T1-weighted imaging with injection of the contrast agent of Gd-DTPA was performed in 111 lesions and fluid attenuated inversion recovery （FLAIR） was performed on 37 lesions, and among them, 2 cases were subjected to MR perfusion weighted imaging （PWI）. Results： Unilateral temporal lobe was involved in 48 cases of REP, bilateral temporal lobe in 56 cases of REP respectively, with a total of 160 lesions. The REP in the white matter displayed hyper-intensity signal on T2-weighted imaging which could be homogenous, whereas areas with heterogeneous hypo-intensity signal could be seen in 59 of them otherwise with hyper-intensity signal, and 91 lesions of white matter were associated with gray matter lesions with an appearance of hypo-intensity signal on T1-weighted imaging and hyper-intensity signal on T2-weighted imaging. In 111 lesions with the Gd-DTPA enhanced T1-weigthed imaging, 91 showed the enhancement of brain parenchyma. Hemorrhage and hemosiderosis occurred in 5 lesions of REP. Conclusion： REP in NPC has a multiplicity of the imaging features on MRI, in addition to the common involvement of white matter, including other relatively frequent findings, such as the involvement of gray matter, hemorrhage, hemosiderosis and blood-brain barrier destruction, those could be clearly revealed on MRI.

Treatment outcomes for different subgroups of nasopharyngeal carcinoma patients treated with intensity-modulated radiation therapy

Although many studies have investigated intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC),sample sizes in the reported studies are usually small and different in outcomes in different T and N subgroups are seldom analyzed.Herein,we evaluated the outcomes of NPC patients treated with IMRT and further explored treatment strategy to improve such outcome.We collected clinical data of 865 NPC patients treated with IMRT alone or in combination with chemotherapy,and classified all cases into the following prognostic categories according to different TNM stages:early stage group (T1-2N0-1M0),advanced local disease group (T3-4N0-1M0),advanced nodal disease group (T1-2N2-3M0),and advanced locoregional disease group (T3-4N2-3M0).The 5-year overall survival (OS),local relapse-free survival (LRFS),and distant metastases-free survival (DMFS) were 83.0%,90.4%,and 84.0%,respectively.The early disease group had the lowest treatment failure rate,with a 5-year OS of 95.6%.The advanced local disease group and advanced nodal disease group had similar failure pattern and treatment outcomes as well as similar hazard ratios for death (4.230 and 4.625,respectively).The advanced locoregional disease group had the highest incidence of relapse and death,with a 5-year DMFS and OS of 62.3% and 62.2%,respectively,and a hazard ratio for death of 10.402.Comparing with IMRT alone,IMRT in combination with chemotherapy provided no significant benefit to locoregionally advanced NPC.Our results suggest that the decision of treatment strategy for NPC patients should consider combinations of T and N stages,and that IMRT alone for early stage NPC patients can produce satisfactory results.However,for advanced local,nodal,and locoregional disease groups,a combination of chemotherapy and radiotherapy is recommended.

Clinical findings and imaging features of 67 nasopharyngeal carcinoma patients with postradiation nasopharyngeal necrosis

Postradiation nasopharyngeal necrosis is an important late effect of radiotherapy that affects prognosis in patients with nasopharyngeal carcinoma.In the present study,we reviewed the clinical and imaging features of 67 patients with pathologically diagnosed postradiation nasopharyngeal necrosis who were treated at Sun Yat-sen University Cancer Center between June 2006 and January 2010.Their clinical manifestations,endoscopic findings,and imaging features were analyzed.Early nasopharyngeal necrosis was limited to a local site in the nasopharyngeal region,and the tissue defect was not obvious,whereas deep parapharyngeal ulcer or signs of osteoradionecrosis in the basilar region was observed in serious cases.Those with osteoradionecrosis and/or exposed carotid artery had a high mortality.In conclusion,Postradiation nasopharyngeal necrosis has characteristic magnetic resonance imaging appearances,which associate well with clinical findings,but pathologic examination is essential to make the diagnosis.

Radiation-induced osteosarcoma of the maxilla and mandible after radiotherapy for nasopharyngeal carcinoma

Background:The increasing incidence of radiation-induced osteosarcoma of the maxilla and mandible(RIOSM) has become a significant problem that can limit long-term survival.The purpose of this study was to analyze the association of clinicopathologic characteristics with treatment outcomes and prognostic factors of patients who developed RIOSM after undergoing radiotherapy for nasopharyngeal carcinoma(NPC).Methods:We reviewed the medical records of 53,760 NPC patients admitted to Sun Yat-sen University Cancer Center during the period August 1964 to August 2012.Of these patients,47 who developed RISOM and met inclusion criteria were included in this study.Two of these 47 patients refused treatment and were then excluded.Results:For all patients treated for NPC at Sun Yat-sen University Cancer Center during the study period,the total incidence of RIOSM after radiotherapy was 0.084%(47/53,760).Two patients(4.4%) had metastases at the diagnosis of RIOSM.Thirty-nine of the 45(86.7%) patients underwent surgery for RIOSM;most patients(24/39;61.5%) who underwent resection had gross clear margins,with 15 patients(38.5%) having either a gross or microscopic positive margin.All patients died.The 1-,2-,and 3-year overall survival(OS) rates for the entire cohort of 45 patients were 53.3%,35.6%and 13.5%,respectively.The independent prognostic factors associated with high OS rate were tumor size and treatment type.Conclusions:RISOM after radiotherapy for NPC is aggressive and often eludes early detection and timely intervention.Surgery combined with postoperative chemotherapy might be an effective treatment to improve patient survival.

Radiation-induced brain injury after a conventional dose of intensity-modulated radiotherapy for nasopharyngeal carcinoma:a case report and literature review

A 61-year-old female nasopharyngeal carcinoma patient was admitted to the hospital with sudden cognitive dysfunction one month after Volumetric Intensity Modulated Arc Therapy(VMAT)conventional dose radiotherapy,and the initial diagnosis was radiation-induced brain injury(RBI).After comprehensive treatment with steroid hormones,the patient’s condition rapidly improved.Typically,in nasopharyngeal carcinoma patients treated with VMAT,the incidence of RBI is extremely low when the temporal lobe dose is less than 65 Gy or 1%of the volume is less than 65 Gy.When this limit is exceeded,RBI may occur in varying degrees.However,in this case,even though the temporal lobe dose was under the prescribed limit,the patient still experienced RBI.The rare observations in this case can be used as a reference,and clinicians should seriously consider the possibility of RBI in similar cases.

Analysis of pathogenic factors of radiation encephalopathy after radiotherapy for nasopharyngeal carcinoma

The authors investigated 242 patients after radiotherapy for nasopharyngeal carcinoma (NC).Of whom 84 developed radiation encephalopathy (REP), the incidence rate(IR) of REP was 34.7%.In various factors associated with REP, the irradiation source, total r

Clinical manifestations of radiation encephalopathy after radiotherapy for nasopharyngeal carcinoma and their comparative analysis with MRI

In order to probe into an optimal method for locating radiation encephalopathy (REP) after radiotherapy for nasopharyngeal carcinoma (NC), 84 consecutive patients with REP who were treated in Nanfang Hospital were observed and their clinical data analysed in comparison with the findings from magnetic resonance imaging (MRI)from 1986 through 1993. The results showed that the early symptoms and signs of REP are mainly mental symptoms due to lesions of the temporal lobes, and signs of the pyramidal tract and cranial nerve lesion syndromes which are associated with brain-stem injury. The clinical features of REP might be classified into 3 stages: early response, state of relative rest and delayed response in the light of the course of the disease. Clinical symptoms included 3 circumstances :general symptoms, local signs of the nervous system and no obvious symptoms, and may be classified into 3 types :temporal lobes, brain stem, and cerebellum types. In this series of patients, 9.5% had no clinical symptoms. It can be seen that the diagnosis of REP could not depend on its clinical manifestations only. It was suggested that the lesions of the temporal lobes is easy to be seen by CT, but MRI examination is needed for displaying the lesions of the brain stem and cerebellum.

Local definitive intensity-modulated radiation therapy recommended for patients initially diagnosed with nasopharyngeal carcinoma with distant metastasis after an effective systemic chemotherapy

Objective The aim of the study was to propose a hypothesis that local definitive intensity-modulated radiation therapy(IMRT) should be recommended for initially diagnosed metastatic nasopharyngeal carcinoma(NPC) and demonstrate its feasibility.Methods Recently published papers on local definitive radiotherapy for initially diagnosed metastatic NPC were reviewed to propose a hypothesis.Results Several studies revealed the survival benefits of adding local definitive radiotherapy to the systemic chemotherapy in patients initially diagnosed with metastatic NPC.Conclusion We suggested that local definitive IMRT should be recommended in patients initially diagnosed with NPC with distant metastasis after an effective systemic chemotherapy, which may possibly prolong their survival time and potentially treat the disease.

A dosimetric comparative study between conformal and intensity modulated radiation therapy in the treatment of primary nasopharyngeal carcinomas: the Egyptian experience

Objective: The study is a comparative study, the aim of which is to compare 3D conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) in treating nasopharyngeal carcinomas; dosimetrically evaluating and comparing both techniques as regard target coverage and doses to organs at risk (OAR). Methods: Twenty patients with nasopharyngeal carcinoma were treated by 3D-CRT technique and another 20 patients were treated by IMRT. A dosimetric comparison was done by performing two plans for the same patient using Eclipse planning system (version 8.6). Results: IMRT had a better tumor coverage and conformity index compared to 3D-CRT plans (P value of 0.001 and 0.004), respectively. As for the dose homogeneity it was also better in the IMRT plans and the reason for this was attributed to the dose inhomogeneity at the photon/electron junction in the 3D-CRT plans (P value 0.032). Also, doses received by the risk structures, particularly parotids, was significantly less in the IMRT plans than those of 3D-CRT (P value 0.001). Conclusion: IMRT technique was clearly able to increase the dose delivery to the target volume, improve conformity and homogeneity index and spare the parotid glands in comparison to 3D-CRT technique.

Effects of oral nutrition support on nutritional status, immune function and radiation damage in patients with nasopharyngeal carcinoma radiotherapy

Objective:To study the effects of oral nutrition support on nutritional status, immune function and radiation damage in patients with nasopharyngeal carcinoma radiotherapy.Methods:Patients with nasopharyngeal carcinoma who received radiotherapy in West China Hospital between and November January 2017 were selected and randomly divided into the nutrition support group who received oral nutrition support and the normal control group who received routine intervention. The levels of nutrition indicators and radiation damage indicators in serum as well as the contents of immune cells in peripheral blood were determined before radiotherapy and 1 week after end of radiotherapy.Results: Compared with those before radiotherapy, serum ALB, PA, TWEAK, Leptin and Ghrelin levels as well as peripheral blood CD3+CD4+, CD3+CD8+, CD3-CD19+ and CD3-CD56+ immune cell contents of nutrition support group didn't change significantly whereas serum TGF-β1, IL-6, IL-17 and MMP9 levels increased significantly 1 week after end of radiotherapy;serum ALB and PA levels as well as peripheral blood CD3+CD4+, CD3+CD8+, CD3-CD19+ and CD3-CD56+ immune cell contents of normal control group decreased significantly whereas TWEAK, Leptin, Ghrelin, TGF-β1, IL-6, IL-17 and MMP9 levels increased significantly 1 week after end of radiotherapy.Conclusion:Oral nutrition support can avoid the damage of nutritional status and immune function and reduce the radiation damage in patients with nasopharyngeal carcinoma radiotherapy.

Recurrent nasopharyngeal Carcinoma and post radiation fibrosis: differentiation with enhanced MRI

Magnetic resonance imaging (MRI) was performed in 40 patients with nasopharyngeal carcinoma (NPC) before and after i.v. administration of Cadolinium-DTPA(Gd-DTPA), for evaluating the role of Gd-DTPA-enhanced imaging in the differentiation of recurrent nasopharyngeal carcinoma (PNPC) from post-radiation fibrosis (RF). MRI diagnosis and findings were confirmedby pathology (n=16) and long-term serial MR/CT and clinical follow-up (n=24), including 3 untreated primary NPC cases,20RNPC cases and 17 RF cases. The results indicated that post-contrast T1 weighted imaging exhibited excellent contrast between thelesion and the surrounding tissue, therefore, it was superior to the Pre-conbet T1WI in showing the relationship between lesionsand adjacent tissues, especially for those lesions located submucosally, and the ones with intl’aCndal invasion. All the NPC andRNPC demonstrated mild to moderate enhancement, with the pattern of homogenous masses or patches. Only 5 cases of the RFgroup demonstrated mild enhancement, which was found in 4 of the 5 cases within one year after radiotherapy. Of the 5 cases,4revealed linear-shaped enhancement. The mean value of enhancement percentage showed marked difference between the twogroups (P<0.05), however, some overlapping existed in their mean ± SD. Gd-DTPA enhanced MR imaging could offer importantinformation for differentiating from RF, on the basis of the intensity and pattern characteristics of the enhancement. It couldalso be helpful in separating thickened mucosa or sinus secretion from tumor, and was superior to unenhanced MR imaging in theearly diagnosis of intracranial involvement of NPC.

Clinical Effect of Biafine in Preventing and Treating Radioactive Skin Destruction of Nasopharyngeal Carcinoma Patients Caused by Concurrent Intensity- Modulated Radiotherapy and Chemotherapy

OBJECTIVE To observe the clinical effect of Biafine cream in preventing and treating radioactive skin destruction of nasopharyngeal carcinoma （NPC） patients induced by synchronized intensity-modulated radiotherapy and chemotherapy. METHODS The patients were treated with Varian-600CD 6 MV X-ray three-dimensional （3D） conformal intensity-modulation radiotherapy （IMRT）, with a 120-blade multiple leaf-blade grating and in combination with synchronal Capecitabine chemotherapy. Fifty-one patients undergoing radiotherapy and chemotherapy were randomized into 2 groups： 25 in the treatment group received a Biafine cream application following the first radiotherapy and / or chemotherapy, while the other 26, served as controls. They received no application of the cream, but only followed normal procedures for conventional radiotherapy and health education. RESULTS The rate of the skin-reaction was 100% in the patients of both groups. A mild radiation reaction （grade-Ⅰ and Ⅱ） occurred as follows： 88.0% （22/25 cases） in the treatment group and 57.7% （15/26 cases） in the control group. A grade-Ⅲ radiation reaction developed in 12.0% （3/25 cases） in the treatment group, and 42.3% （11/26 cases） in the controls. There was a significant difference, P〈0.01 between the two groups. Concerning the degree of the skin response before the patients received a dose of 40 Gy, the radiation reaction emerged in 32.0% （8/25） of the cases in the treatment group, and in 96.2% （25/26） of the cases of the control group. CONCLUSION Biafine cream can effectively reduce the acute irradiation or chemotherapy-induced dermal injury. It can alleviate the patients＇ suffering, improve their quality of life, and can ensure less injurious radiotherapy.

Long-term outcomes of a phase Ⅱ randomized controlled trial comparing intensity-modulated radiotherapy with or without weekly cisplatin for the treatment of locally recurrent nasopharyngeal carcinoma

Background:Salvage treatment for locally recurrent nasopharyngeal carcinoma(NPC) is complicated and relatively limited.Radiotherapy,combined with effective concomitant chemotherapy,may improve clinical treatment outcomes.We conducted a phase Ⅱ randomized controlled trial to evaluate the efficacy of intensity-modulated radiotherapy with concomitant weekly cisplatin on locally recurrent NPC.Methods:Between April 2002 and January 2008,69 patients diagnosed with non-metastatic locally recurrent NPC were randomly assigned to either concomitant chemoradiotherapy group(n = 34) or radiotherapy alone group(n = 35).All patients received intensity-modulated radiotherapy.The radiotherapy dose for both groups was 60 Gy in 27 fractions for 37 days(range 23-53 days).The concomitant chemotherapy schedule was cisplatin 30 mg/m^2 by intravenous infusion weekly during radiotherapy.Results:The median follow-up period of all patients was 35 months(range 2-112 months).Between concomitant chemoradiotherapy and radiotherapy groups,there was only significant difference in the 3-year and 5-year overall survival(OS) rates(68.7%vs.42.2%,P = 0.016 and 41.8%vs.27.5%,P = 0.049,respectively).Subgroup analysis showed that concomitant chemoradiotherapy significantly improved the 5-year OS rate especially for patients in stage rT3-4(33.0%vs.13.2%,P = 0.009),stages Ⅲ-Ⅳ(34.3%vs.13.2%,P = 0.006),recurrence interval >30 months(49.0%vs.20.6%,P = 0.017),and tumor volume >26 cm^3(37.6%vs.0%,P = 0.006).Conclusion:Compared with radiotherapy alone,concomitant chemoradiotherapy can improve OS of the patients with locally recurrent NPC,especially those with advanced T category(rT3-4) and stage(lll-IV) diseases,recurrence intervals >30 months,and tumor volume >26 cm^3.

Treatment results and prognostic analysis of 1093 primary nasopharyngeal carcinoma: the experience of a single institution of Guangzhou in the beginning of the 21st century

Objective： To analyze the treatment results of primary nasopharyngeal carcinoma （NPC） treated in our institution in the beginning of the 21st century to identify key failures and late effects for refining future treatments. Methods： 1093 patients with primary NPC treated during December 2001 and June 2003 were retrospectively analyzed. The distribution according to the AJCC/UICC （2002 edition） staging system was stage Ⅰ in 5.8%, stage Ⅱ 40.2%, stage Ⅲ 32.7% and stage Ⅳa-b 21.3%. Four different ERT techniques were used： fluoroscopy simulation conventional radiotherapy （CR） in 74.3% of patients, computer tomography simulation conventional radiotherapy （CT-sim CR） 14.2%, three-dimensional conformal radiotherapy （3D-CRT） 6.3%, intensity modulated radiotherapy （IMRT） 5.2%. In the whole series, 46.7% of patients had additional treatment with chemotherapy. Results： The 4-year local failure-free rate （LFFR）, nodal failure-free rate, distant metastasis-free rate, progression-free survival and overall survival （OS） was 89.6%, 96.1%, 85.9%, 73.0% and 82.4%, respectively. The stage was the most important prognostic factor. The 4-year OS and LFFR of patients treated by CR, CT-sim CR, 3D-CRT and IMRT was 80.2%, 89.8%, 89.8%, 92.4% and 87.7%, 96.4%, 91.0%, 96.5%, respectively. The morbidity and degree of xerostomia and trismus were lower in the patients treated by 3D-CRT and IMRT than by CR and CT-sim CR. Conclusion： Treatment results of primary NPC in our institution have been substantially improved. Distant metastasis is the main failure. The CT simulation and conformal radiotherapy can enhance the OS and LFFR, and conformal radiotherapy can reduce the morbidity and degree of late effects.

Occipital lymph node metastasis from nasopharyngeal carcinoma:a special case report and literature review

Cervical lymph node metastasis is common in patients with nasopharyngeal carcinoma(NPC),but occipital lymph node metastasis in NPC patients has not yet been reported.In this case report,we describe an NPC patient with occipital lymph node metastasis.The clinical presentation,diagnostic procedure,treatment,and outcome of this case were presented,with a review of the related literature.

Long-term Therapeutic Outcome and Prognostic Factors of Patients with Nasopharyngeal Carcinoma Receiving Intensity-modulated Radiotherapy: An Analysis of 608 Patients from Low-endemic Regions of China

Objective To evaluate the long-term outcome and prognostic factors of patients with nasopharyngeal carcinoma(NPC)from low-endemic regions of China who received definitive intensity-modulated radiation therapy(IMRT).Methods The clinical data from 608 patients with newly-diagnosed non-metastatic NPC who have received initial treatment at our cancer center from January,2008 to December,2013 were retrospectively reviewed.All patients received definitive IMRT,and 87.7%received platinum-based chemotherapy.Results The median follow-up duration was 51 months(follow-up rate,98.5%;range,10–106 months)for the entire cohort.The 5-year overall survival rate was 79.7%.The 5-year local relapse-free survival rate,regional relapse-free survival rate,distant metastasis-free survival rate and progression-free survival rate were 92.4%,93.3%,79.2%and 74.3%,respectively.A total of 153 patients had experienced treatment failure,with distant metastasis as the primary cause in 77.1%(118/153).Patients with T4 or N3 diseases had a significantly poorer prognosis than other subcategories.Stage T4 and N3 were closely associated with distant metastasis,with the metastatic rate of 29.3%and 45.5%,respectively.Conclusion IMRT provides patients with non-metastatic NPC with satisfactory long-term survival.Both T stage and N stage are important prognostic factors for NPC patients.Patients with T4 or N3 diseases have significantly increased distant metastatic rates and poor survival time.

Stereotactic radiotherapy for the treatment of nasopharyngeal carcinoma: a Meta-analysis of 1371 cases in China

Objective The aim of this study was to clarify the outcomes of stereotactic radiotherapy for the treatment of local residual and(or) local recurrent nasopharyngeal carcinoma and to promote scientific clinical treatment and research on it in China and other countries by creating a large data resource.Methods This Meta-analysis conducted a literature search using the China National Knowledge Infrastructure database for all clinical research articles on stereotactic radiotherapy for the treatment of local residual and(or) local recurrent nasopharyngeal carcinoma in China.Data on patient cohort numbers and other research factors were recorded for every relevant clinical research article.Calculated and analyzed these fact sheets to pave the way for the objective of this project.Results A total of 40 clinical research articles including 1,371 patients in China from 1998 to 2012 were identified.The average cohort size was 34 patients(range 9-98 patients).The average total radiation dose range was 16-33.6 Gy.The average study or treatment duration was 3.51 years.The calculated average follow-up time was 31.59 months.Conclusion The study provided the largest resource for further research and Meta-analyses to determine the clinical pathway of stereotactic radiotherapy for the treatment of local residual and(or) local recurrent nasopharyngeal carcinoma.The results indicated that variability in the total radiation dose,treatment or research time,and follow-up duration may have contributed to the complications and side effects of stereotactic radiotherapy for local residual and(or) local recurrent nasopharyngeal carcinoma in China.The calculated average total radiation dose,follow-up time,and treatment and research durations may be referenced for future treatment and research.This study also proposed worldwide cooperation for the metaanalysis of research articles on stereotactic radiotherapy for treating local residual and(or) local recurrent nasopharyngeal carcinoma.

Study on the effect of PET/CT-guided nasopharyngeal carcinoma target delineation on the dose received by endangered organs

Objective:To compare the differences of radiation-induced doses between 18F-FDG-PET/CT and CT/MRI-guided target delineation in nasopharyngeal carcinoma in intensity-modulated radiotherapy.Methods:A total of 31 patients with locally advanced nasopharyngeal carcinoma receiving treatment in our hospital from December 2016 to December 2017 were studied in this research,and 18F-FDG-PET/CT and CT/MRI were used to guide the target delineation to develop an intensity-modulated radiotherapy plan(experimental group and control group).The dose differences between GTV and endangered organs in the two groups were compared.Results:Comparison of primary tumor volume:PET/CT was smaller than CT/MRI,and volumes of T3 and T4 were significantly different(P<0.001).Comparison of the two delineation plans,in terms of PGTV in Dmin,Dmean,and D95,the data of experimental group was smaller than that of the control group;in Dmax,the PGTV of the experimental group was larger than that of the control group with P<0.001 considered as a significant difference.In Dmin and Dmax,doses of experimental groups of the spinal cord were lower than those of the control group,showing a significant difference(P=0.022,0.042);In Dmean,there was no difference between the two groups.In Dmax doses of an experimental group of the brainstem and parotid gland were significantly smaller than the control group(P=0.001,0.047)while there was no difference between Dmin and Dmean.There was no difference between the two groups of Dmin,Dmean,and Dmax in the doses received by chiasm and temporal lobe.Conclusion:PET/CT guided target delineation is applied in the simultaneous dose adjustment of intensity-modulated radiation therapy in patients with advanced nasopharyngeal carcinoma.In primary lesion targets shown by MRI/CT,the tumor tissue of PET/CT concentration zone was given a higher dose with relatively smaller average dose and minimum dose in the overall tumor target area.Statistics also showed that the doses received by the spinal cord,brain stem,and parotid gland were reduced with no effect on the optic chiasm and temporal lobe.In the future,more studies should probe into the long-term effects of dose changes on lesion control and endangered organs.

PET/CT imaging of delayed radiation encephalopathy following radiotherapy for nasopharyngeal carcinoma

Background With the significant improvement in the survival of patients with nasopharyngeal carcinoma （NPC） undergoing radiotherapy and the growing availability of the sophisticated imaging modalities, the number of radiation encephalopathy （RE） cases relating to NPC radiotherapy is increasing. In this study, we investigated the metabolic and density changes of the compromised brain tissues during delayed RE using a positron-emission tomography-computed tomography （PET/CT） to provide clinical evidences for the diagnosis of delayed RE following radiotherapy for NPC. Methods The PET/CT manifestations and the clinical data of 53 pathologically confirmed NPC patients with delayed RE following radical radiotherapy and 15 healthy volunteers were investigated. The standardized uptake values （SUV） of the bilateral temporal lobes, the occipital lobe and the brain stem were measured respectively; and then the metabolic reduction rate of 88 temporal lobes and 13 brain stems were calculated for a statistical comparison between the two groups. Results The earliest case of delayed RE in the investigated patients occurred 1.5 years after radiotherapy. Delayed RE frequently involved the inferior temporal lobe. For patients with delayed RE confirmed by clinical symptoms and imaging findings, PET maintained a 100% coincidence rate with CT; however, in the 25 temporal lobes of the 35 delayed RE patients, PET revealed obvious hypometabolic changes whereas CT displayed normal density. The incidence of brain stem metabolic reductions was 24.5% （13/53） in the investigated patients, including 4 patients with hypometabolic changes shown by PET and negative finding shown by CT. The incidence of granuloma adjacent to the hypometabolic region in the temporal lobe was 12.5% （11/88）. Conclusion Delayed RE patients exhibit significant hypometabolic changes in the inferior temporal lobe, captured by PET much earlier than by CT. PET/CT offers a valuable means for the diagnosis of delayed RE in subacute stages and granuloma formation.

Comparison of Volumetric and Dosimetric Variations in Nasopharyngeal Carcinoma during Intensity-modulated Radiation Therapy with and without Neoadjuvant Chemotherapy

Objective Patients with nasopharyngeal carcinoma(NPC)undergoing intensity-modulated radiation therapy(IMRT)may experience significant volumetric and dosimetric variations throughout the treatment course.However,neoadjuvant chemotherapy may reduce the extent of these variations.This study was carried out to evaluate volumetric and dosimetric changes in target volumes and organs at risk(OARs)during IMRT in patients with locally advanced NPC who received concurrent chemoradiotherapy(CCRT)alone or in combination with neoadjuvant chemotherapy(NACT).Methods 35 NPC patients were recruited for this study and divided into the NACT(n=15)and CCRT(n=20)groups.Computed tomography(CT)scans were performed before neoadjuvant chemotherapy,before IMRT,before the 24 th fraction of IMRT,and after treatment.The original plan(plan 0)was based on CT images collected before IMRT.Hybrid plan 1(plan 1)and hybrid plan 2(plan 2)were generated by applying the beam configurations of plan0 to the CT scans collected before the 24 th fraction of IMRT and after treatment.Volumetric and dosimetric variations were assessed by comparing the results of plan 0 with those of plan 1 and plan 2.Results In the NACT group,compared with that in plan 0,the primary gross tumor volume(GTVnx)decreased by 33.2%±18.4%and 50.5%±12.6%in plan1 and plan 2,respectively.In the CCRT group,the corresponding reduction rates in plan 1 and plan 2 were 49.4%±8.0%and 77.8%±28.1%,respectively.The volume decrease rates in the NACT group were less than those in the CCRT group(P<0.001).In the NACT group,compared with that of plan0,the dose to 95%of the volume(D95)for the planning target volume of the primary tumor(PTVnx)decreased by 1.0%±0.7%and 0.6%±0.6%in plan 1 and plan 2,respectively.In the CCRT group,the corresponding decrease rates in plan 1 and plan 2 were 4.2%±3.8%and 6.1%±6.3%,respectively.The decrease rate of D95 for PTVnx in the NACT group was less than that in the CCRT group(P<0.001).Similar results among the plans were found in terms of D99,Dmean,V93 for PTVnxand PTVnd,and Dmeanfor the parotid glands.Conclusion Neoadjuvant chemotherapy reduces the extent of volumetric and dosimetric variations in target volumes and OARs during IMRT and,thus,helps achieve better target volume coverage,protects adjacent important structures,and minimizes unnecessary replanning during radiotherapy.