***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: AIM In patients with non-hypersecreting adrenal masses , tumor characterization is clinical ly relevant to establish the appropriate treatment planning . The aim of this study was to comparatively characterize such adrenal lesions using MR and radionuclide techniques . METHODS Thirty patients with non-hypersecreting unilateral adrenal tumors underwent both MR and adrenal scintigraphy . MR was performed using SE T1- ( pre- and post-gadolinium DTPA ) and T2-weighted images as well as in- and out-phase chemical-shift imaging ( CSI ) . MR qualitative and quantitative ( signal intensity ratios ) evaluation was performed . Radionuclide studies consisted of iodine-131 nor-cholesterol ( n=20 ) , iodine-131 MIBG ( n=15 ) and fluorine-18 FDG PET ( n=11 ) scans . Histology ( n=16 ) , biopsy ( n=3 ) or clinical -imaging follow-up ( n=11 ) demomstrated 13 adenomas , 3 cysts , 2 myelolipomas , 4 pheochromocytomas ( pheos ) , 4 carcinomas , 1 sarcoma and 3 metastases . Comparative imaging analysis was focused on adenomas , pheos and malignant tumors . RESULTS Qualitative MR evaluation showed : signal T2-hyperintensity in 46 % of adenomas and in 100 % of pheos and malignant tumors , no gadolinium enhancement in 92 % of adenomas and definite signal intensity loss on CSI in 100 % of such tumor lesions , gadolinium enhancement in 100 % of pheos and in 63 % of malignancies and no absolute change of signal intensity on CSI in 100 % of both pheos and malignancies . Quantitative MR analysis demonstrated : significantly higher signal T2-hyperintensity of pheos compared to adenomas and malignancies as well as significantly higher enhancement after gadolinium in pheos compared to adenomas and malignancies ( p<0.03 ) . Radionuclide studies showed significantly increased nor-cholesterol uptake only in adenomas ( n=13 ) , significant MIBG accumulation only in pheos ( n=4 ) and FDG activity only in malignant adrenal lesions ( n=8 ) . CONCLUSION MR techniques may provide some presumptive criteria to characterize non-hypersecreting adrenal masses , such as no gadolinium enhancement and definite signal intensity loss on CSI in adenomas or quantitatively measured T2-hyperintensity and gadolinium enhancement in pheos . On the other h and , radionuclide modalities offer more specific findings in this setting since nor-cholesterol and MIBG scans are respectively able to reveal benign tumors such as adenoma and pheochromocytoma , while FDG imaging allows identification of malignant adrenal lesions . Adrenal scintigraphy is recommended in those patients , when MR images are uncertain or inconclusive Purpose . To evaluate the accuracy of the washout in the differential diagnosis between adenomas and nonadenomas and to compare the obtained results in delayed CT scans at 5 , 10 and 15 minutes . Methods . Fifty patients with adrenal masses were prospect ively evaluated .  CT scans were performed by using a 320-row MDCT device , before and after injection of contrast material . In 25 cases , delayed scans were performed at 5′ and 10′ ( group 1 ) , while in the remaining 25 , at 5′ and 15′ ( group 2 ) . Absolute and relative wash-out percentage values ( APW and RPW ) were calculated . Results . Differential diagnosis between adenomas and nonadenomas was obtained in 48/50 ( 96 % ) cases , with sensitivity , specificity , and accuracy values of 96 % , 95 % , and 96 % , respectively . In group 1 , APW and RPW values were , respectively , 69.8 % and 67.2 % at 5′ and 75.9 % and 73.5 % at 10′ for adenomas and 25.1 % and 15.8 % at 5′ and 33.5 % and 20.5 % at 10′ for nonadenomas . In group 2 , APW and RPW values were 63 % and 54.6 % at 5′ and 73.8 % and 65.5 % at 15′ for adenomas and 22 % and 12.5 % at 5′ and 35.5 % and 19.9 % at 15′ for nonadenomas . Conclusions . The evaluation of the wash-out values in CT scans performed at 5′ , 10′ , and 15′ provides comparable diagnostic results . CT scans performed at 5′ are , therefore , to be preferred , since they reduce the examination time and patient discomfort OBJECTIVES This study was undertaken : ( 1 ) to evaluate the usefulness of unenhanced computed tomography ( CT ) , magnetic resonance imaging ( MRI ) and CT guided biopsy for the characterization of adrenal masses in patients with operable non-small-cell lung cancer ( NSCLC ) and ( 2 ) to evaluate the situations in which CT guided biopsy is absolutely necessary before potentially curative resection of NSCLC . METHODS Consecutive patients with operable NSCLC underwent unenhanced adrenal CT with density measurements of any adrenal mass over 1 cm in diameter . An adrenal mass was considered as an adenoma when its density was below 10 Hounsfield Units and a metastasis when its density exceeded 10 Hounsfield Units . Then patients underwent MRI , the signal on the T2 weighted images from the enlarged gl and was classified adenoma or metastasis in comparison with that from the liver parenchyma . CT guided biopsy was performed after a pheochromocytoma was eliminated . Unenhanced CT attenuation values and signal intensity values on MRI were correlated with histopathologic results . RESULTS Of the 443 patients , 32 had an adrenal mass consisting of adrenal metastases in 18 cases and adenomas in 14 cases . On CT , 3/14 ( 21 % ) of the adenomas were misdiagnosed as metastases ( their densities exceeded 10 Hounsfield Units ) and 2/18 ( 11 % ) of the metastases were misdiagnosed as adenomas ( their densities were below 10 Hounsfield Units ) . On MRI , none of the metastases were misdiagnosed as an adenoma ( 100 % sensitivity ) but 7/14 ( 50 % ) of the adenomas were misdiagnosed as metastases ( signal superior to that of liver ) . Overall , a diagnostic certainty of metastasis could not be obtained in 25/32 patients ( 78 % ) . CT guided biopsy with 100 % sensitivity and specificity corrected all the inaccurate results of CT and MRI without any morbidity . CONCLUSION Despite extensive morphological evaluation with unenhanced CT and conventional MRI , CT guided biopsy is necessary for most patients referred to surgery for an operable NSCLC and an adrenal mass UNLABELLED We design ed a prospect i ve study to evaluate the accuracy of magnetic resonance imaging in distinguishing a benign from a malignant adrenal mass in patients with otherwise operable non-small-cell lung cancer . METHODS Potentially operable non-small-cell lung cancer was prospect ively staged . If a unilateral adrenal mass was found by computed tomographic scanning , respiratory compensated and cardiac gated thin section magnetic resonance imaging of the adrenal gl and s was done . One radiologist interpreted the magnetic resonance imaging scan blinded and , on the basis of the relative signal strengths of the T1- and T2-weighted images , judged whether the adrenal mass was benign or malignant . The patients then underwent a percutaneous needle biopsy of the adrenal mass , if technically feasible . If the result of the needle biopsy was nondiagnostic or if the biopsy was not feasible , an adrenalectomy through a posterior approach was performed . RESULTS Twenty-seven patients with a unilateral adrenal mass entered the study -11 men and 16 women whose ages ranged from 42 to 75 years ( median 58 years ) . Four patients had epidermoid and 23 adenocarcinoma of the lung . The clinical locoregional stage was I in 9 , II in 1 , IIIA in 16 , and IIIB in 1 . Twenty-five completed the magnetic resonance imaging procedure . Five adrenal masses ( 19 % ) were metastatic non-small-cell lung cancer ( adenocarcinoma = 4 , epidermoid = 1 ) ; 22 masses ( 81 % ) were benign ( adenoma = 20 , hyperplasia = 2 ) . There were no significant differences in age , sex , histologic type , or locoregional stage between those with a benign versus a malignant mass . However , the malignant masses were significantly larger ( 3.8 + /- 1.9 cm ; range 2.5 to 7.1 ; median 3.1 ) than the benign masses ( 2.0 + /- 0.4 cm , range 1.2 to 2.8 ; median 2.0 ) ( p < 0.001 ) . Among those having magnetic resonance imaging ( n = 25 ) , the technique correctly predicted a malignant mass in the four patients with a histologically confirmed metastasis from non-small-cell lung cancer . However , among the 21 histologically benign masses , the magnetic resonance imaging was interpreted as benign in 5 , malignant in 14 , and indeterminate in 2 . Therefore , although the false-negative rate was 0 % , the false-positive rate was 67 % . CONCLUSION Most adrenal masses in patients with otherwise operable non-small-cell lung cancer are benign . Currently available magnetic resonance imaging methods can not replace biopsy The purpose of the study is to evaluate the ability of Gd-enhancement and fat-suppressed MR imaging operating at midfield strength to characterize incidentally discovered adrenal masses . Sixty patients with 72 adrenal masses incidentally discovered during US or CT exams were studied with a 0.51 MR unit following clinical and laboratory evaluation . After Gd-DTPA intravenous administration a modified three-point Dixon technique was performed in all patients . This technique provided three images sets : conventional T1-weighted SE images , fat-suppressed T1-weighted images and water-suppressed T1-weighted images . Diagnosis was established by means of surgery ( 11 lesions ) , fine-needle biopsy ( 21 lesions ) and stability on ultrasonographic follow-up for at least 1 year ( range , 12 - 87 months ) from adrenal lesion discovery ( 40 masses ) . In most of adenomas ( n = 55 ) an homogeneous enhancement was observed on postcontrast T1WI ; however , 15 out of these lesions showed a small focal spot of high intensity in Gd-enhanced fat-suppressed images . On the contrary , malignant conditions ( n = 6 ) and pheochromocytoma ( n = 1 ) , all had inhomogeneous signal intensities which were relatively higher after Gadolinium injection as compared with the liver . The fat suppression technique demonstrated areas of bright signal intensity related to high vascularity . The performance of three observers in order to differentiate malignant from benign conditions showed sensitivity , specificity , diagnostic accuracy , positive and negative predictive values of 100 , 88.5 , 90 , 50 and 100 % on the basis of gadolinium enhancement only , by utilizing the Dixon technique . In conclusion , although Gd-enhancement and fat-suppressed sequence helped correctly differentiate among the groups of incidentally discovered adrenal masses , the degree of overlap suggests that it is still difficult to characterize individual patients . However , the modified three-point Dixon technique after contrast material administration appears to be a further capability of midfield MRI in the characterization of adrenal tissue CONTEXT Most adrenal incidentalomas are nonfunctioning adrenocortical adenomas ( ACAs ) . Adrenocortical carcinomas ( ACCs ) are rare but should be recognized at an early stage . OBJECTIVE The objective of the study was to evaluate the usefulness of (18)F-fluorodeoxyglucose positron emission tomography ( (18)F-FDG PET ) to predict malignancy in patients without a previous history of cancer . DESIGN This was a prospect i ve , multicenter study from 2001 to 2006 . SETTING The study was conducted at a network of seven university hospitals in Paris . PATIENTS Seventy-seven patients were included . All underwent  surgery  because of hypersecretory and /or growing benign lesions ( n = 18 ) , obvious ACCs ( n = 21 ) , or radiologically indeterminate lesions ( n = 38 ) . MAIN OUTCOME MEASURE The degree of (18)F-FDG PET uptake [ maximum st and ardized uptake value ( maxSUV ) ] was related to the pathological findings serving as a reference , and its diagnostic value was compared with that of computerized tomography ( CT ) scan . RESULTS Pathology eventually diagnosed 43 ACAs , 22 ACCs , and 12 nonadrenocortical lesions . Using a cutoff value above 1.45 for adrenal to liver maxSUV ratio , the sensitivity and specificity to distinguish ACAs from ACCs were , respectively , 1.00 ( 95 % confidence interval 0.85 - 1.00 ) and 0.88 ( 95 % confidence interval 0.75 - 0.96 ) . 
    Output:
    
Limited data suggest that CT density > 10HU has high sensitivity for detection of adrenal malignancy  in participants with no prior indication for adrenal imaging , that is , masses with ≤10HU are unlikely to be malignant .
Despite their widespread use in routine assessment , there is insufficient evidence for the diagnostic value of individual imaging tests in distinguishing benign from malignant adrenal masses .