***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: OBJECTIVES Firstly , to compare the findings of interictal 18F-fluorodeoxyglucose ( FDG ) positron emission tomography ( PET ) and of single photon emission computed tomography ( SPECT ) using 99mTc-hexamethyl propylene-amine-oxime ( HMPAO ) and 123I-iomazenil in localising the epileptogenic cortex in patients who were c and i date s for epilepsy surgery , but in whom clinical findings , video EEG monitoring ( V-EEG ) , MRI , and neuropsychological evaluations did not give any definite localisation of the seizure onset . Secondly , to assess the ability of these functional methods to help in the decision about the epilepsy surgery . METHODS Eighteen epileptic patients were studied with FDG-PET and iomazenil-SPECT . HMPAO-SPECT was performed in 11 of these 18 patients . Two references for localisation was used — ictal subdural EEG recordings ( S-EEG ) and the operated region . RESULTS Fifteen of 18 patients had localising findings in S-EEG . FDG-PET findings were in accordance with the references in 13 patients and iomazenil-SPECT in nine patients . HMPAO-SPECT visualised the focus less accurately than the two other methods . In three patients S-EEG showed independent bitemporal seizure onset . In these patients FDG-PET showed no lateralisation . However , iomazenil-SPECT showed temporal lobe lateralisation in two of them . CONCLUSION FDG-PET seemed to localise the epileptogenic cortex more accurately than interictal iomazenil-SPECT in patients with complicated focal epilepsy Despite advances in morphological imaging , some patients with lung cancer are found to have nonresectable disease at surgery or die of recurrence within yr of surgery . We performed a prospect i ve study in 109 patients to compare the accuracy of whole-body positron emission tomography ( PET ) using fluorine-18 deoxyglucose ( 18FDG ) and conventional imaging ( CI ) methods for the staging of non-small cell lung cancer ( NSCLC ) . When CI or PET study suggested metastatic disease , confirmation was obtained by biopsy or follow-up information . As compared to CI , 18FDG-PET correctly changed the N stage in 22 patients ( 33 % ) and the M stage in 15 patients ( 14 % ) . For the detection of distant metastases , PET study showed five false-positive sites and no false-negative cases . Currently , the accuracy of PET  in the detection of M stage is 96 % . Our study shows that visual interpretation of whole-body fluorine-18 deoxyglucose-positron emission tomography images can improve the diagnostic accuracy in the staging of non-small cell lung cancer . Further experience is needed to establish if metabolic imaging would be a cost-effective tool in the future management of lung cancer The main aim of the study was to evaluate the use of positron emission tomography using fluoro-deoxyglucose ( PET-FDG ) imaging for the detection of squamous cell carcinoma of the head and neck . Fifty-four consecutive patients with malignancies involving the head and neck were studied prospect ively . Thirty-one patients presented with primary disease and 23 were suspected of recurrent or residual disease . All patients underwent full clinical staging , PET-FDG scans and anatomical imaging , 37 underwent computed tomography ( CT ) , 13 magnetic resonance ( MR ) and four had both CT and MR .  Clinical assessment , CT/MR , PET-FDG and histological examination were all evaluated independently of each other . All 31 primary head and neck malignant tumours were detected by  PET-FDG .  Based on 16 patients who underwent neck dissections , the sensitivity and specificity of PET-FDG for detecting nodal disease was 67 % and 100 % respectively , compared with clinical assessment of 58 % and 75 % and CT/MR of 67 % and 25 % . In all 12 patients , PET-FDG correctly identified the presence of absence or recurrent or residual disease .  PET-FDG staged 13 post-treatment necks with an accuracy of 100 % as compared to CT/MR which was accurate in 7 of 13 and clinical assessment which was accurate in eight . Three sites of abnormal tracer uptake unrelated to malignancy were recorded as incidental findings ( m and ibular osteomyelitis , 1 : post glossectomy site , 2 ) . PET-FDG was more accurate than CT/MR for identifying primary and recurrent tumours as well as metastatic lesions in the neck . If these diagnostic properties of PET-FDG are confirmed in further prospect i ve studies , it could prove a valuable adjunct for the management of head and neck cancer During an 18 month period 39 patients were evaluated with  [ 18F ] fluorodeoxyglucose-PET ( FDG-PET ) for primary brain tumours . These included patients with suspected newly diagnosed tumours and patients with known tumours who were being evaluated for possible recurrence or increasing tumour grade . Scans were performed on a 951 - 31 Siemen 's PET scanner with 4 mm resolution . Scanning time was about 20 minutes per patient . All patients had undergone recent cerebral MRI .  These patients were divided into two groups . In the first group ( 30 ) MRI and PET concurred on the diagnosis . The second group ( nine ) comprised those where the interpretation of MRI and PET was different or there was a question of the diagnosis on MRI . This group comprised three patients in whom MRI suggested recurrent tumour and PET inaccurately suggested radiation necrosis ; two patients with newly diagnosed enhancing lesions on MRI in whom PET was useful in distinguishing strokes from tumour ; two patients with prior gliomas with new enhancing isolated lesions on MRI in whom PET scan accurately depicted radiation necrosis ; and two patients with newly diagnosed enhancing lesions on MRI in whom PET scan was helpful in distinguishing multiple sclerosis from tumour in one but not in the other . Therefore , of the 39 patients , PET was helpful in five in distinguishing tumour from other disease processes ; but , in so far as influencing treatment , it seemed helpful in only two . Thus PET seems to be of limited value as an aid to evaluating and treating patients with suspected or known primary brain tumours UNLABELLED The aim of this prospect i ve study was to investigate if high uptake of 18F-fluoro-2-deoxy-D-glucose ( FDG ) is associated with aggressiveness in head and neck cancer and low probability of survival . METHODS Thirty-seven patients with squamous-cell carcinoma of the head and neck underwent FDG-PET in the fasting state before cancer treatment .  FDG uptake in primary tumor was quantitated as the st and ardized uptake value of FDG normalized to the predicted lean body mass ( SUVlean , n = 37 ) and as the graphically determined metabolic rate for FDG ( rMR[FDG ] , n = 34 ) . Paraffin-embedded tumor sample s were used for histologic evaluation , and expression of cytokeratin and Ki-67 antigen were assessed by immunohistochemistry . RESULTS Interobserver agreement for the determination of quantitative uptake of FDG  in tumors was excellent ( r2 = 0.996 , p < 0.00001 ) , and all 37 primary tumors were visualized . A high uptake of FDG  as assessed by SUVlean was associated with a higher than the median mitotic count ( p = 0.01 ) , absence of keratinization ( p = 0.03 ) , low or moderate histological grade of differentiation ( p = 0.046 ) and advanced stage ( p = 0.03 ) , but not with Ki-67 expression ( p = 0.11 ) . The overall survival of patients with a SUVlean lower than or equal to the median value ( 9.0 ) was clearly better in univariate analysis than that of patients with a SUVlean higher than the median ( 3-yr survival 73 % versus 22 % , relative risk of death ( RR ) 4.2 , 1.6 - 11.0 ) . However , in a multivariate analysis the only independent predictors of survival were the mitotic count ( RR 4.0 , 1.4 - 11.7 ) and stage ( 3.8 , 1.2 - 12.2 ) . CONCLUSION High uptake of FDG in untreated head and neck cancer is associated with advanced disease , and may portend poor survival . Aggressive treatment approaches should be considered for patients presenting with a tumor with high uptake of FDG UNLABELLED This study evaluated various quantitative criteria for analysis of breast imaging with PET using the radiolabeled glucose analog 18F-fluorodeoxyglucose ( FDG ) . METHODS In a prospect i ve study , 73 patients with abnormal mammography or palpable breast masses scheduled for biopsy were investigated with  PET .  A total of 97 breast tumors were evaluated by histology , including 46 benign and 51 malignant tumors . Using a whole-body PET scanner , attenuation-corrected images were acquired between 40 and 60 min after tracer injection . For Patlak analysis , dynamic data acquisition was obtained in 24 patients . To differentiate between benign and malignant breast tumors , receiver operating characteristic curves were calculated using incrementally increasing threshold values for tumor/ nontumor ratios based on average and maximum activity values per region of interest , st and ardized uptake values ( corrected for partial volume effect , normalized to blood glucose , partial volume effect and blood glucose , using the lean body mass as well as the body surface area ) and calculating the FDG influx rate ( K ) assessed by Patlak analysis . RESULTS Quantification of FDG uptake in breast tumors provided objective criteria for differentiation between benign and malignant tissue with similar diagnostic accuracy as compared with visual analysis . Applying correction for partial volume effect and normalization by blood glucose yielded the highest diagnostic accuracy . CONCLUSIONS These quantitative methods provided accurate evaluation of PET data for differentiating benign from malignant breast tumors . Quantitative assessment is recommended to complement visual image interpretation with the potential benefit of reduced interobserver variability Recent studies have shown limitations of morphological imaging in staging mediastinal lymph node involvement in lung cancer . In contrast to computed tomography ( CT ) , which depends primarily on anatomical imaging features , positron emission tomography ( PET ) with 18-fluorodeoxyglucose ( FDG ) depends mainly on the metabolic characteristics of a tissue for the diagnosis of disease . We have performed a prospect i ve study comparing FDG-PET and CT of the thorax in the presurgical assessment of the mediastinum in 50 patients with newly diagnosed non-small cell lung cancer ( NSCLC ) .  CT and PET scans were interpreted separately , and results were compared to pathological staging obtained during thoracotomy .  Hilar or mediastinal lymph node involvement was present in 58 % . In staging for lymph node involvement , CT had a sensitivity of 72 % and specificity of 81 % , whereas PET had a sensitivity and specificity of 90 % and 86 % , respectively . When the PET study was compared to histological results , there were four cases showing more advanced mediastinal involvement with PET and four cases showing less involvement with PET . From our preliminary results , we conclude that positron emission tomography with 18-fluorodeoxyglucose is significantly more accurate than computed tomography in the mediastinal staging of non-small cell lung cancer PURPOSE To prospect ively compare the accuracy of positron emission tomography ( PET ) with 2-[fluorine-18 ] fluoro-2-deoxy-D-glucose ( FDG ) with that of computed tomography ( CT ) in the nodal staging of non-small cell lung cancer . MATERIAL S AND METHODS PET and contrast material -enhanced CT were performed in 47 patients suspected of having or with newly diagnosed non-small cell lung cancer . Each imaging study was evaluated separately , and nodal stations were localized according to the American Thoracic Society mapping system . Extensive lymph node sampling ( 599 nodes from 191 nodal stations ) of the ipsi- and contralateral tracheobronchial and mediastinal nodal stations was performed at thoracotomy and /or mediastinoscopy . Imaging findings were correlated with histopathologic staging results . RESULTS The sensitivity of PET and CT  was 89 % and 57 % , respectively , for the staging of N2 or N3 disease in mediastinal nodes ; specificity was 99 % and 94 % , respectively ; positive predictive value was 96 % and 76 % , respectively ; negative predictive value was 97 % and 87 % , respectively ; and accuracy was 96 % and 85 % , respectively . In assigning the correct N stage , PET was correct in 96 % and CT in 79 % of cases . CONCLUSION PET with FDG appears to be superior to CT for nodal staging of non-small cell lung cancer The noninvasive staging of axillary lymph nodes for metastases is investigated in patients with breast cancer prior to surgery by positron emission tomography ( PET ) with fluorine- l8-fluoro-2-deoxy-d-glucose ( 18F-FDG ) . In 124 patients with newly diagnosed breast cancer , whole-body PET was performed to determine the average differential uptake ratio ( DUR ) of18F-FDG in the axillary lymph nodes . Results were correlated with the number of the dissected lymph nodes , size of 
    Output:
    
The results of the Delphi study indicated that the four most important research priorities for the NHS , in descending order of their importance , are : ( 1 ) the relative cost-effectiveness of ( a ) full ring PET , ( b ) gamma camera PET using coincidence imaging and ( c ) existing diagnostic strategies to determine staging prior to operative intervention for lung cancer ; ( 2 ) partial ring PET compared with full ring PET in oncology ( 3 ) the relative cost-effectiveness of ( a ) full ring PET , ( b ) gamma camera PET using coincidence imaging and ( c ) existing diagnostic strategies to stage and monitor treatment response in breast cancer ; ( 4 ) the relative cost-effectiveness of ( a ) gamma camera PET using coincidence imaging and ( b ) 511 keV collimated positron imaging for assessing myocardial viability when selecting patients for revascularisation surgery .
The findings of this project , which was undertaken rapidly in order to inform HTA research prioritization in the UK , provide a contemporary overview of the potential clinical role for PET in the NHS .
Evidence is needed that using PET as a