***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND The choice of treatment in patients with oral malignancies depends on accurate pretreatment staging and particularly the detection of lymph node involvement . Therefore staging of the neck should be as accurate as possible . PATIENTS One hundred and six patients with histologically proven squamous cell carcinoma of the oral cavity . STUDY DESIGN In a prospect i ve study , PET using fluoro-desoxy-glucose ( 18F-FDG ) , ultrasound , CT and MRI of head and neck were compared with the postoperative histologic tissue evaluation .  Two thous and one hundred and ninety-six neck lymph nodes of 106 patients were investigated . In all patients the tumour was resected and a lymph node dissection was performed . RESULTS The diagnostic procedures showed the following results when compared with the histological findings : PET : sensitivity 70 % , specificity 82 % , accuracy 75 % ; Ultrasound : 84 % , 68 % , 76 % ; CT : 66 % , 74 % , 70 % ; MRI : 64 % , 69 % 66 % . Thus PET showed the highest specificity while ultrasound had the highest sensitivity compared with the other staging procedures . A nonsignificant correlation was found between the size of a lymph node metastasis and the ability to detect it . In 10 patients , second primary tumours or distant metastases were detected by PET only . CONCLUSION Due to the high number of small lymph node metastases from oral cavity carcinoma , the non-invasive neck staging methods are limited to a maximum accuracy of 76 % . Elective neck treatment should be m and atory for all patients with squamous cell carcinoma of the oral cavity Conventional work-up ( CWU ) with chest radiography , abdominal ultrasonography , and skeletal scintigraphy has limited value in M staging of nonkeratinizing nasopharyngeal carcinoma ( NPC ) . Our aim was to evaluate whether 18F-FDG PET could replace CWU by comparing their diagnostic efficacies . Methods : Patients with histologically proven nonkeratinizing NPC and no prior treatment were prospect ively enrolled . All study participants underwent CWU and 18F-FDG PET for primary M staging . Distant metastasis was considered to be present if there was any reliable evidence identified within 1 y after diagnosis . The comparative diagnostic efficacies of 18F-FDG PET , CWU , and the combination of 18F-FDG PET and CWU ( PET+CWU ) were evaluated using the areas under the receiver-operating-characteristic ( ROC ) curves . Results : Sixty-one ( 20.3 % ) of 300 eligible patients were found to have distant metastases . On a patient-based analysis , 18F-FDG PET was found to be more effective than CWU ( P < 0.001 ) , whereas it was equally effective with PET+CWU ( P = 0.130 ) . On region-based analyses , 18F-FDG PET was more effective than skeletal scintigraphy and chest radiography for detecting bone metastases ( P < 0.001 ) and chest metastases ( P < 0.001 ) , respectively . 18F-FDG PET  and abdominal ultrasound were equally effective for detecting hepatic metastases ( P = 0.127 ) . On region-based analyses , the combination of 18F-FDG PET and CWU did not yield any noticeable increase in diagnostic efficacy . Conclusion : 18F-FDG PET can replace CWU in primary M staging of nonkeratinizing NPC OBJECTIVE Because of the high risk of secondary primary malignancies in addition to possible distant metastases , whole-body evaluation is critically important in patients with head and neck cancer . We evaluated the clinical usefulness of whole-body (18)F-fluorodeoxyglucose ( FDG ) positron emission tomography ( PET ) before initial treatment . STUDY DESIGN We performed whole-body FDG PET in 26 patients with head and neck cancer ( squamous cell carcinoma , n = 20 ; salivary gl and carcinoma , n = 6 ) before initial treatment .  FDG images were prospect ively evaluated , and further imaging studies were performed if required . Final diagnosis for the presence or absence of distant lesions was made by analysis of the pathologic findings of surgical specimens or by analysis of the clinical follow-up data for more than 1 year . RESULTS PET images showed FDG avid lesions distant from the head and neck area in 3 of 26 patients ( 11.5 % ) . Two patients were confirmed to have secondary primary cancer ( one with colon cancer in the early stage and another with small lung metastasis from postoperative colon cancer ) . They were diagnosed and treated properly both for the head and neck cancer and the secondary primary cancer . One patient was confirmed to have large lung metastasis from head and neck cancer , and appropriate treatment was selected . CONCLUSIONS Whole-body FDG PET has a clinical impact on the management of patients with head and neck cancer by detecting secondary primary malignancies as well as distant metastases UNLABELLED Distant metastasis is an important issue for nasopharyngeal carcinoma ( NPC ) . The potential value of PET using 18F-FDG has not been well defined . This prospect i ve study investigated the impact of 18F-FDG PET in NPC patients with stage M0 disease . METHODS From April 2001 to June 2003 , 140 NPC patients ( 118 primary and 22 primary recurrent ) with stage M0 ( negative results from chest radiography , liver sonography , and whole-body bone scanning ) underwent 18F-FDG PET to check for distant metastases . Confirmatory MRI or CT was performed if any abnormal 18F-FDG uptake was found at distant sites . The distant lesion was confirmed pathologically , if feasible , and was followed up clinical ly and with imaging for at least 6 mo . RESULTS 18F-FDG PET detected 26 true-positive metastatic sites in 18 ( 12.9 % ) of the 140 patients , among whom 14 had primary and 4 had recurrent tumors . The patient-based sensitivity and specificity of 18F-FDG PET for distant metastases were 100 % and 86.9 % , respectively . Mediastinal lymph nodes ( n = 8) were the most common sites , followed by lung , liver , and bone ( n = 5 each ) and by other lymph nodes ( n = 3 ) . In patients with primary tumors , advanced nodal status ( N2 - 3 ) was a statistically significant variable associated with development of distant metastases ( P = 0.044 ) . For recurrent NPC , neither age , sex , initial tumor stage , grade of differentiation , nor nodal stage showed a statistically significant difference between patients with and patients without distant metastases . CONCLUSION 18F-FDG PET is valuable in avoiding aggressive locoregional radiotherapy in some NPC patients by the revelation of occult distant metastases , especially in patients with primary disease at a nodal stage of N2 - 3 It was of interest to determine the impact of FDG-PET/CT on general therapy management and radiotherapy ( RT ) planning in patients with stage IV head and neck tumours . The study was conducted prospect ively between March 2006 and March 2007 in 35 patients with histologically confirmed , locally advanced squamous cell carcinomas of the head and neck . Prior to primary radiochemotherapy , whole-body and head/neck FDG-PET/CT was performed . The FDG-PET information was integrated into RT planning . By comparison with anatomical imaging , the FDG-PET/CT yielded the following additional information : distant metastases in 17.1 % ( 6/35 ) , second primary tumours in 11.4 % ( 4/35 ) , and changes in nodal status based on metabolic activity , i.e. upstaging in 34.3 % ( 12/35 ) or downstaging in 22.9 % ( 8/35 ) . As a result , treatment strategy was changed from curative to palliative in six patients , and additional curative therapy was implemented following exclusion of distant metastases in two patients with a simultaneous local second primary tumour . The discordant nodal status found with head/neck FDG-PET/CT compared with anatomical imaging led to modification of radiotherapy volume and dose in 20 patients ( 57.1 % ) . From the radiotherapist 's perspective FDG-PET/CT is therefore useful and justifiable in the management of stage IV head and neck tumours OBJECTIVE To evaluate the impact of 18F-fluoro-deoxy-glucose positron emission tomography after st and ard diagnostic workup in patients with advanced head and neck squamous cell carcinoma on staging and radiation treatment planning . STUDY DESIGN Prospect i ve controlled study . METHODS Forty-eight patients ( 42 men and 6 women ; mean age , 61 y ; age range , 35 - 85 y ) with histologically confirmed , advanced-stage ( any T , N > or = N2 or T > or = T3 , any N ) mucosal head and neck squamous cell carcinoma underwent positron emission tomography .  The routine workup consisting of physical examination , panendoscopy , chest x-ray film , and contrast-enhanced high-resolution helical computed tomography scan ( H RCT ) was used for comparison . End points were the extent of lymph node disease , distant metastases , and second primary tumors . RESULTS In 41 of 48 patients ( 85 % ) the lymph node findings between H RCT and positron emission tomography were concordant . In three patients positron emission tomography led to an upstaging of the tumor in its N category , and in four patients positron emission tomography underestimated lymph node involvement .  Positron emission tomography revealed more difficulties in delineating lymph node metastases adjacent to the primary tumor than did H RCT , but was superior for the detection of distant and contralateral lymph node metastases . Positron emission tomography suggested distant metastatic lesions in 6 of 48 patients ( 13 % ) . Cytological workup confirmed distant metastases in two ( 4 % ) and second primary tumors in another two patients ( 4 % ) . Positron emission tomography results were false-positive in two ( 4 % ) patients because of inflammatory changes . CONCLUSIONS Whole-body PET is able to assess lymph node involvement , distant metastases , and second primaries in a single study . Even after a routine clinical staging , positron emission tomography leads to a change of treatment in approximately 8 % of patients Purpose The aim of our study was to prospect ively evaluate whether intravenous contrast media in integrated positron emission tomography and computed tomography ( PET/CT ) with 18F-fluorodeoxyglucose ( 18F-FDG ) significantly contributes to evaluation of primary head and neck cancers compared with unenhanced PET/CT , regional contrast-enhanced CT of head and neck ( neck CE-CT ) and regional magnetic resonance imaging of head and neck ( neck MRI ) . Methods Subjects were 42 consecutive patients ( 35 men , 7 women ; age range : 36–91 years ) with biopsy-proven primary head and neck cancers . Lesion detection of primary and nodal sites and TNM classification were assessed on a per-patient basis . McNemar test and κ statistics were employed for statistical analyses . Results Forty patients ( 95 % ) were successfully followed up : 24 patients had nodal disease and 3 had distant metastasis . Contrast-enhanced and unenhanced PET/CT detected 98 and 95 % of the primary tumours , respectively , and both detected 92 % of patients with nodal disease , which revealed no statistically significant difference . Accuracy for T status was 75 and 73 % , respectively , which proved significantly more accurate than neck CE-CT , which had an accuracy of 53 % ( p = 0.0133 and 0.0233 , respectively ) . Neck MRI  correctly classified the T status in 58 % of patients ; however , no statistically significant difference was found between PET/CT and neck MRI . Contrast-enhanced PET/CT , unenhanced PET/CT , neck CT and neck MRI  correctly staged the N status in 90 , 90 , 79 and 90 % of patients , respectively , with no statistically significant difference . Overall TNM classification was correctly classified in 68 and 65 % of patients , respectively . Weighted κ values between enhanced and unenhanced PET/CT  for primary tumour detection , nodal detection , T status and N status were 0.655 , 1.000 , 0.935 and 1.000 , respectively . Conclusion We found almost perfect correlation between enhanced and unenhanced PET/CT for lesion detection and initial staging of primary head and neck cancers . Routine contrast administration for PET/CT imaging may not be justified BACKGROUND Detection of metastatic disease in head and neck cancer patients is critical to preoperative planning , because patients with distant metastasis will not benefit from surgical therapy . Conventional radiographic modalities , such as CT and MR , give excellent anatomic detail but poorly identify unenlarged lymph nodes harboring metastatic disease . OBJECTIVE A pilot study was conducted to evaluate the usefulness of 18-fluorodeoxyglucose positron emission tomography ( FDG-PET ) detection of metastatic disease in patients with advanced-stage head and neck cancer . METHODS Total body FDG-PET imaging was performed in a prospect i ve manner on 12 consecutive patients with a new diagnosis of stage 
    Output:
    
Whole-body PET and PET-CT have good diagnostic performance in initial M staging of head and neck cancer ; although PET-CT tends to have higher accuracy than PET