***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: Purpose This study compared the effectiveness of fluorodeoxyglucose ( FDG ) positron emission tomography ( PET ) with computed tomography ( CT ) , magnetic resonance imaging ( MRI ) , or both for the assessment of recurrent squamous cell carcinoma of the head and neck . The value of quantifying the st and ardized uptake values ( SUV ) to distinguish recurrent neoplasm from inflammatory lesions and normal structures was also evaluated . Methods Forty-three patients with head and neck cancer were examined with F-18 FDG PET at least 4 months after their last course of radiation therapy ( mean , 11 months ) . The SUVs were measured in visually identified regions of abnormally increased activity and were compared with the values in normal mucosa , the base of the tongue , and the hard palate to determine if an optimal cutoff value exists for diagnosing recurrence of malignant lesions . The final diagnosis of recurrence was made based on biopsy or at least 6 months ’ clinical follow-up . Results FDG PET correctly detected recurrence in 20 of 22 patients who had 45 discrete lesions located in the field of the upper aerodigestive tract . Two false-negative and three false-positive results were identified . The accuracy of FDG PET was 88 % ( 38 of 43 patients ) , compared with 66 % ( 25 of 38 patients ) for CT , MRI , or both . Although there was a significant difference of SUVs ( P = 0.0036 ) between the recurrent lesions and normal structures , the optimal cutoff values were difficult to define . Conclusions Visual analysis of FDG PET is significantly more accurate in the diagnosis of recurrent squamous cell cancer of the head and neck than are CT or MRI . However , single SUV quantification does not significantly enhance efficacy Purpose The purpose of this prospect i ve study was to evaluate the usefulness of 18F-fluorodeoxyglucose ( FDG ) and 11C-choline positron emission tomography (PET)/computed tomography ( CT ) for detecting recurrences of advanced head and neck cancer after combined intra-arterial chemotherapy and radiotherapy .  Additionally , we surveyed the time period during which an effective negative predictive value could be maintained after the first follow-up PET/CT examination and estimated the optimal timing of a second PET/CT examination for detecting late recurrences . Methods Fifty-three subjects ( 36 men and 17 women ; mean age : 59.4 ± 11.5 years ) with advanced head and neck squamous cell carcinoma were recruited .  Post-treatment 18F-FDG PET/CT and 11C-choline examinations were performed in all patients between 8 and 12 weeks after combined intra-arterial chemotherapy and radiotherapy . The PET/CT images were evaluated using a patient-based analysis and a lesion-based analysis . All of the patients were prospect ively followed for at least 9 months after the post-treatment PET/CT examination , with surveillance using conventional images ( including CT and /or MRI ) and a physical examination performed every 3 months . Results Recurrences , as determined using the patient-based analysis , were eventually confirmed in 18 , 6 and 5 patients at 3 , 4–6 and 7–9 months after the post-treatment PET/CT examination , respectively . The sensitivity and specificity of the 18F-FDG PET/CT and the 11C-choline PET/CT examinations to predict recurrence within 3 months were higher ( FDG : 89 and 91 % ; choline : 83 and 80 % , respectively ) than for recurrence detection 6 months ( FDG : 67 and 90 % ; choline : 62 and 76 % , respectively ) and 9 months later ( FDG : 59 and 92 % ; choline : 55 and 75 % , respectively ) . The lesion-based analysis showed that the maximum st and ardized uptake value of 18F-FDG and 11C-choline in the recurrent lesions were correlated with each other , compared with their relation in scar tissues ( R2 = 0.492 and 0.197 , respectively ) . Conclusion 11C-choline was not superior to 18F-FDG for the detection of recurrent head and neck cancer . Both modalities had difficulty identifying recurrences at 4–9 months after the post-treatment PET/CT examination . In patients with advanced head and neck cancer who have received combined therapy , a second post-treatment PET/CT examination to check for late recurrences should be performed within 4–6 months after the first post-treatment PET/CT examination PURPOSE [(18)F]Fluorodeoxyglucose positron emission tomography (FDG-PET)/computed tomography ( CT ) imaging may improve assessment of radiation response in patients with head and neck cancer , but it is not yet known for which patients this is most useful . We conducted a prospect i ve trial to identify patient population s likely to benefit from the addition of functional imaging to the assessment of radiotherapy response . PATIENTS AND METHODS Ninety-eight patients with locally advanced cancer of the oropharynx , larynx , or hypopharynx were prospect ively enrolled and treated with primary radiotherapy , with or without chemotherapy . Patients underwent FDG-PET/CT and contrast-enhanced CT imaging 8 weeks after completion of treatment . Functional and anatomic imaging response was correlated with clinical and pathologic response . Imaging accuracy was then compared between imaging modalities . RESULTS Although postradiation maximum st and ard uptake values were significantly higher in nonresponders compared with responders , the positive and negative predictive values of FDG-PET/CT scanning were similar to those for CT alone in the unselected study population . Subset analyses revealed that FDG-PET/CT outperformed CT alone in response assessment for patients at high risk for treatment failure ( those with human papillomavirus [ HPV ] -negative disease , nonoropharyngeal primaries , or history of tobacco use ) . No benefit to FDG-PET/CT was seen for low-risk patients lacking these features . CONCLUSION These data do not support the broad application of FDG-PET/CT for radiation response assessment in unselected head and neck cancer patients . However , FDG-PET/CT may be the imaging modality of choice for patients with highest risk disease , particularly those with HPV-negative tumors . Optimal timing of FDG-PET/CT imaging after radiotherapy merits further investigation Purpose We performed a prospect i ve comparison of the diagnostic capability of integrated fluorodeoxyglucose ( FDG ) positron emission tomography (PET)/computed tomography ( CT ) ( PET/CT ) , 3-T whole-body magnetic resonance imaging ( WB-MRI ) and their combination in detecting malignancy in treated oropharyngeal or hypopharyngeal squamous cell carcinoma ( OHSCC ) . Methods Seventy-nine OHSCC patients at a high risk of residual disease or suspected to have recurrence after the completion of chemoradiation were included in the study . All patients underwent PET/CT and WB-MRI within 10 days of each other . Histology and follow-up data were used as the reference st and ard . The McNemar test was used to compare sensitivity and specificity , while the area under the receiver-operating characteristic curve ( AUC ) was used for comparison of diagnostic capabilities . Results Twenty-nine patients ( 36.7 % ) had residual/recurrent tumours or second primary tumours . Overall , there was a trend towards increased sensitivity and diagnostic capability for PET/CT compared with WB-MRI ( 72.4 vs 55.2 % , p = 0.13 ; 0.826 vs 0.753 , p = 0.24 , respectively ) . The diagnostic capability of combined interpretation of PET/CT and WB-MRI was similar to PET/CT alone ( 0.827 vs 0.826 , p = 0.97 ) but was significantly higher than WB-MRI alone ( 0.827 vs 0.753 , p = 0.04 ) . Conclusion PET/CT showed a trend towards higher diagnostic capability than 3-T WB-MRI in detecting residual/recurrent tumours or second primary tumours in OHSCC . The combined use of PET/CT and WB-MRI provided more added value to WB-MRI alone than to PET/CT alone . Additional PET/CT can be useful in patients with question able MRI findings of malignancy OBJECTIVE To assess the clinical effect of an early follow-up positron emission tomography ( PET ) examination at the time of the first routine clinical control in patients with advanced-stage head and neck squamous cell carcinoma ( HNSCC ) . DESIGN Prospect i ve , nonr and omized , case-control study . SETTING Single referral center . PATIENTS AND INTERVENTION A total of 26 patients ( mean age , 56 years ) with histologically confirmed stage III-IV HNSCC underwent PET before and approximately 6 weeks after the end of a combined treatment with radiation and chemotherapy with curative intent .  The PET findings were confirmed by histologic analysis and a 6-month clinical follow-up . MAIN OUTCOME MEASURES The presence of distant metastases , secondary synchronous cancers , and residual locoregional tissue was confirmed , and the effect on further clinical management was assessed . RESULTS Using PET , we correctly identified residual tumor tissue , distant metastases , or a second primary tumor in 10 patients , 5 of whom had no clinical evidence of such findings . Results were true negative in 14 cases ; false positive in 1 ; and false negative in 1 . Sensitivity and specificity for follow-up PET scans were 90.9 % and 93.3 % , respectively . All patients with positive findings were evaluated for further treatment such as salvage surgery . CONCLUSIONS Whole-body PET scanning approximately 6 weeks after completion of a combined treatment regimen with radiation and chemotherapy can reliably identify locoregional residual cancer and distant metastases or secondary tumors in patients with advanced-stage HNSCC and has a direct influence on management decisions UNLABELLED Our purpose was to prospect ively evaluate the efficacy of PET with (18)F-FDG 1 mo after the completion of radiotherapy in patients with squamous cell carcinoma of the head and neck ( SCCHN ) . METHODS Ninety-seven patients underwent (18)F-FDG PET scans before and after radiotherapy for nondisseminated SCCHN . The first scans were obtained no more than 4 wk before the start of radiotherapy , and follow-up scans were obtained 1 mo after the completion of radiotherapy . (18)F-FDG PET images were analyzed using st and ardized uptake values ( SUVs ) . All patients were followed for at least 6 mo or until death . RESULTS The median SUVs of preradiotherapy primary sites and nodes were 6.5 ( range , 2.3 - 23.0 ) and 5.6 ( range , 1.2 - 16.8 ) , respectively . The median SUVs of postradiotherapy primary sites and nodes were 1.8 ( range , basal status value to 9.7 ) and 1.8 ( range , basal status value to 8.6 ) , respectively . Evaluation of the postradiotherapy status of tumors in these SCCHN patients showed the sensitivity of (18)F-FDG PET to be 88 % , the specificity to be 95 % , and the overall diagnostic accuracy to be 94.9 % . CONCLUSION Our results indicate that (18)F-FDG PET might be a valuable imaging method for evaluating the response to radiotherapy in patients with SCCHN . One month after the completion of radiotherapy is not too early for follow-up (18)F-FDG PET to be performed to evaluate the response to radiotherapy PURPOSE A multi-institutional , prospect i ve , r and omized trial was undertaken in patients with advanced head- and -neck squamous cell carcinoma to address ( 1 ) the validity of using pathologic risk features , established from a previous study , to determine the need for , and dose of , postoperative radiotherapy ( PORT ) ; ( 2 ) the impact of accelerating PORT using a concomitant boost schedule ; and ( 3 ) the importance of the overall combined treatment duration on the treatment outcome . METHODS AND MATERIAL S Of 288 consecutive patients with advanced disease registered preoperatively , 213 fulfilled the trial criteria and went on to receive therapy predicated on a set of pathologic risk features : no PORT for the low-risk group ( n = 31 ) ; 57.6 Gy during 6.5 weeks for the intermediate-risk group ( n = 31 ) ; and , by r and om assignment , 63 Gy during 5 weeks ( n = 76 ) or 7 weeks ( n = 75 ) for the high-risk group . Patients were irradiated with st and ard techniques appropriate to the site of disease and likely areas of spread . The study end points were locoregional control ( LRC ) , survival , and morbidity . RESULTS Patients with low or intermediate risks had significantly higher LRC and survival rates than those with high-risk features ( p = 0.003 and p = 0.0001 , respectively ) , despite receiving no PORT or lower dose PORT , respectively . For high-risk patients , a trend toward higher LRC and survival rates was noted when PORT was delivered in 5 rather than 7 weeks . A prolonged interval between surgery and PORT in the 7-week schedule was associated with significantly lower LRC ( p = 0.03 ) and survival ( p = 0.01 ) rates . Consequently , the cumulative duration of combined therapy had a significant impact on the LRC ( p = 0. 
    Output:
    
Conclusions PET and PET/CT are highly accurate in detecting residual and /or recurrent HNSCC .
PET/CT is more specific than PET alone .
Specificity is also greater for scans performed more than 12 weeks after radiotherapy with or without chemotherapy .
The authors support the use of PET/CT after 12 weeks posttreatment for the assessment of residual or recurrent disease