***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: The purpose of this study was to compare the diagnostic accuracy of contrast-enhanced ultrasound ( CEUS ) with spiral computed tomography ( SCT ) for the characterization of focal liver lesions ( FLL ) and to determine the degree of correlation between the two techniques . Seventy-seven FLL ( 45 hepatocellular carcinomas ; 12 metastases ; ten hemangiomas ; two regenerating/dysplastic nodules ; eight focal nodular hyperplasias ) detected with ultrasound ( US ) were prospect ively evaluated by CEUS using a second-generation contrast agent and SCT ( with an interval of no more than one month between the two techniques ) . Independent observers made the most probable diagnosis and the results were compared with the final diagnoses ( histology n = 59 ; MRI n = 18 ) . Statistical analysis was performed by the Chi-square and Kappa tests . CEUS provided a correct , specific diagnosis in 69/77 ( 90 % ) of the FLL , while SCT did so in 67/77 ( 87 % ) . The sensitivity , specificity , and diagnostic accuracy for malignancy were 91 % , 90 % , and 91 % , respectively , for CEUS and 88 % , 89 % , and 88 % , respectively , for SCT . No statistically significant difference was found between CEUS and SCT in the characterization of FLL ( p > 0.05 ) . In addition , agreement between the two imaging techniques was good ( k = 0.75 ) . We conclude that CEUS and SCT provide a similar diagnostic accuracy in the characterization of FLL , with a good degree of correlation between the two techniques Aim : The aim was to evaluate the diagnostic value of contrast-enhanced ultrasound in the differential diagnosis of focal liver lesions , in a blinded experiment . In clinical routine the examiner can generally be influenced by the patient ’s history . Method : 62 patients with focal liver lesions , which could not be clearly differentiated and diagnosed by conventional ultrasound , were examined with contrast-enhanced ( BR1 , SonoVue ® , Bracco ) ultrasound and included in a blinded prospect i ve and r and omized study . The examinations performed on a Sequoia 512 ( Acuson ) in a coherent contrast imaging method were recorded by an S-VHS recorder and afterwards analyzed by an examiner who did not know the patient ’s history . The basis of the diagnosis was the dynamic appearance and enhancement of the ultrasound contrast enhancer in different phases of liver perfusion . The conformation of the diagnoses was made by corresponding reference methods , as computer tomography , magnetic resonance imaging , biopsy and clinical follow-up . Results : The following diagnoses were confirmed by reference methods : 18 patients with metastases , 4 hepatocellular carcinomas , 19 haemangiomas , 6 focal nodular hyperplasias , 13 patients with focal fatty infiltration and 2 patients with focal fatty sparing . 59 out of 62 patients with one or more liver lesions were correctly diagnosed by contrast-enhanced ultrasound . Conclusion : Second-generation ultrasound contrast enhancers improve the differential diagnosis of benign and malignant liver lesions considerably , especially in a blinded study OBJECTIVE The purpose of this study was to assess the efficacy and safety of contrast-enhanced ultrasound performed with perflubutane microbubbles in comparison with unenhanced ultrasound and dynamic CT in the characterization of focal liver lesions during the vascular phase of imaging and in the detection of lesions during the Kupffer phase . SUBJECTS AND METHODS A total of 196 patients were enrolled at 15 centers in Japan . Vascular phase images were obtained before contrast injection until 1 minute after injection . Kupffer phase images were obtained 10 minutes after injection . Dual-phase CT was performed as determined by st and ard clinical practice at each center . Unenhanced ultrasound , contrast-enhanced ultrasound , and CT images were read by blinded review ers , and the results they reached regarding characterization and detection were compared with reference st and ard findings made by onsite investigators . The safety observation period was 72 hours after contrast administration . RESULTS Among the 190 patients included in the characterization analysis , the accuracy of contrast-enhanced ultrasound ( 88.9 % ) was significantly greater than that of unenhanced ultrasound ( 68.4 % ) and dynamic CT ( 80.5 % ) ( p < 0.001 and p = 0.008 ) . Among the 191 patients in the detection analysis , the efficacy of contrast-enhanced ultrasound in detection of lesions was significantly higher than that of unenhanced ultrasound and dynamic CT ( p < 0.001 and p = 0.008 ) , predominantly because more metastatic lesions were detected ( both p < 0.001 ) . In particular , contrast-enhanced ultrasound was superior to dynamic CT in the detection of metastatic lesions measuring 1 cm or smaller . The incidence of adverse events was 49.2 % and that of adverse drug reactions was 10.4 % . All adverse drug reactions were mild . CONCLUSION Compared with unenhanced ultrasound and dynamic CT , contrast-enhanced ultrasound with perflubutane microbubbles improved diagnostic efficacy in both characterization and detection of focal liver lesions with no serious adverse drug reactions PURPOSE The aim of the study was to investigate the ability of contrast-enhanced sonography ( CEUS ) with the contrast agent SonoVue to differentiate between benign and malignant focal liver lesions . METHODS In a prospect i ve study , we examined 317 patients ( 204 males , 113 females , aged 59 + /- 12 years ) with focal liver lesions detected by B-mode gray-scale sonography . After intravenous injection of 1.2 mL SonoVue , the liver was examined continuously for 3 minutes using low-MI sonography with contrast-specific software . Final diagnosis was established by histopathology , CT , MRI , or HIDA-scintigraphy . RESULTS Two hundred nine patients had malignant focal lesions , including 107 hepatocellular carcinomas , 70 metastases , 26 cholangiocellular carcinomas , and 6 other types of malignancy . One hundred eight patients had benign focal lesions , including 30 regenerative nodules , 30 hemangiomas , 13 cases of focal nodular hyperplasia , 12 abscesses , 8 cases of necrosis , 7 cases of focal steatosis areas , and 8 other benign lesions . Hypoenhancement or no enhancement in the late phase was found in 91 % of the malignant lesions but in only 37 % of the benign lesions ( p < 0.001 , sensitivity = 64 % , specificity = 93 % ) . Hyperenhancement in the late phase was found in 20 % of the benign lesions but in none of the malignant lesions ( p < 0.001 , sensitivity = 21 % , specificity = 100 % ) . Hyperenhancement in the early phase with diffuse complete enhancement was found in 30 % of the patients with malignant lesions but in only 2 % of the patients with benign lesions ( p < 0.001 , sensitivity = 30 % , specificity = 98 % ) . CEUS had a sensitivity of 90 % , a specificity of 99 % , and an accuracy of 89 % in the diagnosis of malignant liver lesions . CONCLUSION CEUS is helpful in the differentiation between benign and malignant focal liver lesions OBJECTIVE The purpose of this study was to assess the diagnostic performance of real-time contrast-enhanced sonography in characterization of small focal liver lesions ( FLLs ; < or = 3.0 cm in diameter ) . METHODS Two hundred small FLLs in 200 patients were examined by contrast-enhanced sonography using a contrast-specific mode of contrast pulse sequencing and a sulfur hexafluoride-filled microbubble contrast agent . The sonographic images were review ed by 2 independent readers . A 5-point confidence level was used to discriminate malignant from benign FLLs , and specific diagnoses were recorded . The diagnostic performances were evaluated by receiver operating characteristic ( ROC ) analysis , and the interobserver agreement was analyzed by weighted kappa statistics . RESULTS After review of contrast-enhanced sonography , ROC analysis revealed significant improvement in differentiating between malignant and benign small FLLs that the areas under the ROC curve were 0.856 at baseline sonography versus 0.954 at contrast-enhanced sonography for reader 1 ( P < .001 ) and 0.857 versus 0.954 for reader 2 ( P = .003 ) . The sensitivity , negative predictive value , and accuracy for both readers also improved significantly after contrast agent administration ( all P < .001 ) . A better result of specific diagnosis was obtained ( 38.5 % [ 77/200 ] at baseline sonography versus 80.5 % [ 161/200 ] at contrast-enhanced sonography for reader 1 and 34.5 % [ 69/200 ] versus 80.5 % [ 161/200 ] for reader 2 ; both P < .001 ) after contrast agent administration , and a better interobserver agreement was achieved ( kappa = 0.425 at baseline sonography versus 0.716 at contrast-enhanced sonography ) . CONCLUSIONS Real-time contrast-enhanced sonography improves the diagnostic performance in small FLLs compared with baseline sonography OBJECTIVE The objective of our study was to compare the usefulness of contrast-enhanced sonography with baseline sonography in detecting malignant liver lesions . SUBJECTS AND METHODS This prospect i ve study included 116 patients . All patients underwent a preoperative conventional sonography examination followed by sonography after injection of contrast agent combined with the use of perfusion software ( vascular recognition imaging or pulse subtraction imaging ) .  Histopathologic analysis was the reference st and ard used to compare the diagnostic value of baseline sonography versus contrast-enhanced sonography . RESULTS Eighty-two patients underwent hepatic surgery , 31 did not because of disseminated lesions , and the remaining three patients did not meet inclusion criteria . Three hundred six surgically proven lesions were taken into account for comparison of the two techniques : 147 were detected on baseline sonography and 177 on contrast-enhanced sonography . Histopathologic analysis revealed 233 malignant and 73 benign lesions . Sensitivity and specificity were improved on contrast-enhanced sonography compared with baseline sonography for the detection of malignant lesions : 68.7 % versus 58.8 % and 67 % versus 50.7 % , respectively . Contrast-enhanced sonography detected 23 additional malignant lesions that had been seen as lacuna at the portal venous phase and characterized as 19 benign nodules , thus improving the performance of sonography in 13.7 % of the cases . CONCLUSION Contrast injection improved the sensitivity and specificity of baseline sonography and should be performed in routine practice if hepatic surgery is being considered for the management of liver lesions BACKGROUND Contrast-enhanced ultrasonography ( CEUS ) is increasingly accepted in clinical setting s for diagnostic imaging of focal liver lesions ( FLLs ) . This study aim ed to assess the efficacy of CEUS in the characterization of FLLs in comparison with final diagnosis based on gold st and ard assessment . METHODS The study was approved by the local ethics committee and participating patients provided written informed consent . A total of 148 patients with 164 FLLs were studied .  Unenhanced ultrasonography ( US ) and CEUS were performed using fundamental and harmonic imaging , respectively . Contrast enhancement was assessed during the arterial , portal and late vascular phases after intravenous administration of contrast ( SonoVue , Bracco , Italy ) . Sensitivity , specificity and diagnostic accuracy of US and CEUS were compared in identifying the lesion as benign , malignant or indeterminate and its actual tumor type . Final diagnosis was established by biopsy ( 129/164 ) , MR imaging ( 11/164 ) or medical history ( 24/164 ) . RESULTS When compared to the gold st and ard , the number of indeterminate diagnoses was reduced from 56.7 % ( 93/164 ) as assessed by fundamental imaging to 6.1 % ( 10/164 ) after SonoVue enhanced US examination . Sensitivity and specificity improved from 49 % and 25 % at baseline US to 93 % and 75 % with CEUS , respectively ( P<0.01 ) . Diagnostic accuracy of CEUS was 88 % in contrast to 41 % of baseline US . CONCLUSION SonoVue enhanced US improves the characterization of FLLs and may limit the need for further investigations OBJECTIVE To determine whether examination of focal liver lesions by pulse inversion sonography in the early perfusion phase of the contrast agent Levovist ( SH U 508A ; Schering AG , Berlin , Germany ) enables distinction between benign and malignant lesions . METHODS Seventy-two patients were examined . The cause of the lesion was confirmed by liver biopsy , computed tomography , or both or by hepatic iminodiacetic acid-enhanced scintigraphy . Forty-two patients had malignant liver lesions , and 30 had benign liver lesions . After injection of 2 g of Levovist intravenously , analysis of Levovist arrival was performed by the interval delay imaging technique for 60 seconds . RESULTS The early arrival of Levovist  less than 30 seconds after injection was used as an indicator for malignancy and had 
    Output:
    
The results of this meta- analysis support the international recommendations on CEUS for the diagnostic work-up of focal liver lesions selecting patients who need further diagnostics