AIM:To evaluate the expression status of S-phase kinase-associated protein 2(Skp2)/cyclin-dependent kinases regulatory subunit 1(Cks1)and p27kip1,and assess the prognostic significance of Skp2/Cks1 expression with p27...AIM:To evaluate the expression status of S-phase kinase-associated protein 2(Skp2)/cyclin-dependent kinases regulatory subunit 1(Cks1)and p27kip1,and assess the prognostic significance of Skp2/Cks1 expression with p27kip1in patients with extrahepatic cholangiocarcinoma.METHODS:Seventy-six patients who underwent curative resection for histologically confirmed extrahepatic cholangiocarcinoma at our institution from December1994 to March 2008 were enrolled.Immunohistochemical staining for Skp2,Cks1,p27kip1,and Ki67,along with other relevant molecular biologic experiments,were performed.RESULTS:By Cox regression analyses,advanced age(>65 years),advanced AJCC tumor stage,poorly differentiated histology,and higher immunostaining intensity of Skp2 were identified as independent prognostic factors in patients with extrahepatic cholangiocarcinoma.Exogenous epidermal growth factor(EGF,especially 0.1-10 ng/mL)significantly increased the proliferation indices by MTT assay and the mRNA levels of Skp2/Cks1 and p27kip1in SNU-1196,SNU-1079,and SNU-245 cells.The protein levels of Skp2/Cks1(from nuclear lysates)and p27kip1(from cytosolic lysate)were also significantly increased in these cells.There were significant reductions in the protein levels of Skp2/Cks1and p27kip1(from nuclear lysate)after the treatment of LY294002.By chromatin immunoprecipitation assay,we found that E2F1 transcription factor directly binds to the promoter site of Skp2.CONCLUSION:Higher immunostaining intensity of Skp2/Cks1 was an independent prognostic factor for patients with extrahepatic cholangiocarcinoma.EGF upregulates the mRNA and protein levels of Skp2/Cks1and p27kip1via the PI3K/Akt pathway and direct binding of E2F1 transcription factor with the Skp2 promoter.展开更多
BACKGROUND： A previous report has identified a significantly higher sensitivity of cancer detection for dedicated grasping basket than brushing at endoscopic retrograde cholangiopancreato- graphy （ERCP）. This study...BACKGROUND： A previous report has identified a significantly higher sensitivity of cancer detection for dedicated grasping basket than brushing at endoscopic retrograde cholangiopancreato- graphy （ERCP）. This study aimed to compare the diagnostic accuracy of Geenen brush and Dormia basket cytology in the differential diagnosis of bile duct stricture. METHOD： The current study enrolled one hundred and fourteen patients who underwent ERCP with both Geenen brush and Dormia basket cytology for the differential diagnosis of bile duct stricture at our institution between January 2008 and December 2012. RESULTS： We adopted sequential performances of cytologic samplings by using initial Geenen brush and subsequent Dormia basket cytology in 59 patients and initial Dormia basket and subsequent Geenen brush cytology in 55 patients. Presampling balloon dilatations and biliary stentings for the stricture were performed in 17 （14.9%） and 107 patients （93.9%）, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of Geenen brush cytology for the diagnosis of malignant bile duct stricture were 75.0%, 100.0%, 100.0%, 66.7% and 83.3%, respectively, and those of Dormia basket cytology were 64.5%, 100.0%, 100.0%, 58.5% and 76.3%, respectively （P=0.347 and 0.827 for sensitivity and accuracy, respectively）. The good and excellent cellular yields （≥grade 2） were obtained by Geenen brush and Dormia basket cytology in 88 （77.2%） and 79 （69.3%） patients, respectively.CONCLUSION： The sensitivity, specificity and accuracy of biliary sampling with a Dormia basket are comparable to those with conventional Geenen brush cytology in the detection of malignant bile duct stricture.展开更多
BACKGROUND For the treatment of gastritis,rebamipide,a mucoprotective agent,and nizatidine,a gastric acid suppressant,are commonly employed individually.AIM To compare the efficacy of Mucotra®SR(rebamipide 150 mg...BACKGROUND For the treatment of gastritis,rebamipide,a mucoprotective agent,and nizatidine,a gastric acid suppressant,are commonly employed individually.AIM To compare the efficacy of Mucotra®SR(rebamipide 150 mg)and Axid®(nizatidine 150 mg)combination therapy with the sole administration of Axid®in managing erosive gastritis.METHODS A total of 260 patients diagnosed with endoscopically confirmed erosive gastritis were enrolled in this open-label,multicenter,randomized,phase 4 clinical trial,allocating them into two groups:Rebamipide/nizatidine combination twice daily vs nizatidine twice daily for 2 weeks.The full-analysis set analysis encompassed 239 patients(rebamipide/nizatidine,n=121;nizatidine,n=118),while the per-protocol analysis included 218 patients(n=110 vs 108).Post-treatment assessments comprised primary(erosion improvement rate)and secondary(erosion and edema cure rates,erythema improvement rates,hemorrhage,and gastrointestinal symptoms)endpoints.Furthermore,drug-related adverse effects were evaluated.RESULTS Primary efficacy assessment showed a statistically significant improvement rate in mucosal erosions in the combination group compared to the control group in the full-analysis set(rebamipide/nizatidine 62.0%,nizatidine 49.2%,P=0.046),with a similar trend noted in the per-protocol analysis(62.7%vs 50.0%,P=0.058).Both groups were effective in curing erosion and edema and improvement of bleeding,erythema,and gastrointestinal symptoms,whereas no inter-group differences were noted.When confined to the participants with gastritis symptoms,improvement of erosion was more optimal in the combination group(63.0%vs 49.5%,P=0.046).No adverse events related to the drugs were observed.CONCLUSION Rebamipide/nizatidine combination is effective in treatment of erosive gastritis.展开更多
AIM: To compare the risk of developing advanced colorectal neoplasm(ACRN) according to age in Koreans.METHODS: A total of 70428 Koreans from an occupational cohort who underwent a colonoscopy between 2003 and 2012 at ...AIM: To compare the risk of developing advanced colorectal neoplasm(ACRN) according to age in Koreans.METHODS: A total of 70428 Koreans from an occupational cohort who underwent a colonoscopy between 2003 and 2012 at Kangbuk Samsung Hospital were retrospectively selected. We evaluated and compared odds ratios(OR) for ACRN between the young-adults(YA < 50 years) and in the older-adults(OA ≥ 50 years). ACRN was defined as an adenoma ≥ 10 mm in diameter, adenoma with any component of villous histology, high-grade dysplasia, or invasive cancer.RESULTS: In the YA group, age(OR = 1.08, 95%CI: 1.06-1.09), male sex(OR = 1.26, 95%CI: 1.02-1.55), current smoking(OR = 1.37, 95%CI: 1.15-1.63), family history of colorectal cancer(OR = 1.46, 95%CI: 1.01-2.10), diabetes mellitus related factors(OR = 1.27, 95%CI: 1.06-1.54), obesity(OR = 1.23, 95%CI: 1.03-1.47), CEA(OR = 1.04, 95%CI: 1.01-1.09) and low-density lipoprotein-cholesterol(OR = 1.01, 95%CI: 1.01-1.02) were related with an increased risk of ACRN. However, age(OR = 1.08, 95%CI: 1.06-1.09), male sex(OR = 2.12, 95%CI: 1.68-2.68), current smoking(OR = 1.38, 95%CI: 1.12-1.71), obesity(OR = 1.34, 95%CI: 1.09-1.65) and CEA(OR = 1.05, 95%CI: 1.01-1.09) also increased the risk of ACRN in the OA group.CONCLUSION: The risks of ACRN differed based on age group. Different colonoscopic screening strategies are appropriate for particular subjects with risk factors for ACRN, even in subjects younger than 50 years.展开更多
Acute mediastinitis is a fatal disease that usually originates from esophageal perforation and surgical infection.Rare cases of descending necrotizing mediastinitis can occur following oral cavity and pharynx infectio...Acute mediastinitis is a fatal disease that usually originates from esophageal perforation and surgical infection.Rare cases of descending necrotizing mediastinitis can occur following oral cavity and pharynx infection or can be a complication of pancreatitis.The most common thoracic complications of pancreatic disease are reactive pleural effusion and pneumonia,while rare complications include thoracic conditions,such as pancreaticopleural fistula with massive pleural effusion or hemothorax and extension of pseudocyst into the mediastinum.There have been no reports of acute mediastinitis originating from pancreatitis in South Korea.In this report,we present the case of a 50-year-old female suffering from acute mediastinitis with pleural effusion arising from recurrent pancreatitis that improved after surgical intervention.展开更多
AIM： To clarify whether insulin resistance and metabolic syndrome are risk factors for erosive esophagitis.METHODS： A case-control study was performed using the database of the Kangbuk Samsung Hospital Medical Scree...AIM： To clarify whether insulin resistance and metabolic syndrome are risk factors for erosive esophagitis.METHODS： A case-control study was performed using the database of the Kangbuk Samsung Hospital Medical Screening Center.RESULTS： A total of 1679 cases of erosive esophagitis and 3358 randomly selected controls were included. Metabolic syndrome was diagnosed in 21% of the cases and 12% of the controls （P 〈 0.001）. Multiple logistic regressions confirmed the association between erosive esophagitis and metabolic syndrome （Odds ratio, 1.25; 95% CI, 1.04-1.49）. Among the components of metabolic syndrome, increased waist circumference, elevated serum triglyceride levels and hypertension were significant risk factors for erosive esophagitis （all P 〈 0.01）. Furthermore, increased insulin resistance （Odds ratio, 0.91; 95% CI, 0.85-0.98） and fatty liver, as diagnosed by ultrasonography （odds ratio, 1.39; 95% CI, 1.20-1.60）, were also related to erosive esophagitis even afl：er adjustment for a series of confounding factors.CONCLUSION： Metabolic syndrome and increased insulin resistance are associated with an increased risk of developing erosive esophagitis.展开更多
BACKGROUND Solitary fibrous tumor(SFT)is an uncommon mesenchymal neoplasm that arises from the pleura.A few SFTs have also been described in extrapleural sites.However,SFT of the thyroid gland is rare.Here,we report a...BACKGROUND Solitary fibrous tumor(SFT)is an uncommon mesenchymal neoplasm that arises from the pleura.A few SFTs have also been described in extrapleural sites.However,SFT of the thyroid gland is rare.Here,we report a case of extrapleural SFT on the thyroid gland,in addition to a literature review.CASE SUMMARY A 59-year-old man visited our hospital in July 2017 complaining of a large mass in his neck.His thyroid function test results,including antibody levels,were within the normal limits.Ultrasonography showed a 4.7 cm×4.0 cm×3.2 cm solitary mass of intermediate suspicion in the left thyroid lobe.A fine-needle aspiration biopsy was subsequently performed.The pathologist reported a benign follicular lesion.However,the size of this nodule increased to 5.5 cm×5.0 cm×3.4 cm by April 2018.After a multidisciplinary discussion,a left lobectomy was performed in May 2018.The specimen showed a well-demarcated,partly encapsulated,soft nodule of whitish and tan/brown color on the cut surface.Light microscopy revealed high cellularity with moderate cytologic atypia.The mitotic count was 5/10 high-power fields.There was no tumor necrosis or lymphovascular invasion.The tumor was CD34-positive and signal transducer and activator of transcription 6-positive.Neither thyroid transcription factor-1 nor cytokeratin expression was detected.The Ki-67 showed intermediate proliferative activity.The final diagnosis was extrapleural SFT of the thyroid gland with a clear resection margin.The patient was discharged without complication three days after the surgery.CONCLUSION In the literature,extrapleural SFT of the thyroid gland has been reported to behave indolently with the capacity for recurrence and rare metastasis,although surgical resection is the treatment of choice.Understanding this disease entity is important for accurate diagnosis and proper management.展开更多
Angiomyofibroblastoma (AMF) is a rare kind of soft tissue tumor that occurs predominantly in the vulva. Due to their location, clinicians often confuse AMF with Bartholin’s cyst or perineal hernia. Radiological evalu...Angiomyofibroblastoma (AMF) is a rare kind of soft tissue tumor that occurs predominantly in the vulva. Due to their location, clinicians often confuse AMF with Bartholin’s cyst or perineal hernia. Radiological evaluation is performed to rule out perineal hernia and invasive neoplasm. Like other benign mesenchymal tumors of vulva, AMF shows indolent behavior and rarely recurs after complete surgical excision.展开更多
Due to its additional frequency response,dual-frequency ultrasound has advantages over conventional ultrasound,which operates at a specific frequency band.Moreover,a tunable frequency from a single transducer enables ...Due to its additional frequency response,dual-frequency ultrasound has advantages over conventional ultrasound,which operates at a specific frequency band.Moreover,a tunable frequency from a single transducer enables sonographers to achieve ultrasound images with a large detection area and high resolution.This facilitates the availability of more advanced techniques that simultaneously require low-and high-frequency ultrasounds,such as harmonic imaging and image-guided therapy.In this study,we present a novel method for dual-frequency ultrasound generation from a ferroelectric piezoelectric micromachined ultrasound transducer(PMUT).Uniformly designed transducer arrays can be used for both deep low-resolution imaging and shallow high-resolution imaging.To switch the ultrasound frequency,the only requirement is to tune a DC bias to control the polarization state of the ferroelectric film.Flextensional vibration of the PMUT membrane strongly depends on the polarization state,producing low-and high-frequency ultrasounds from a single excitation frequency.This strategy for dual-frequency ultrasounds meets the requirement for either multielectrode configurations or heterodesigned elements,which are integrated into an array.Consequently,this technique significantly reduces the design complexity of transducer arrays and their associated driving circuits.展开更多
基金Supported by A grant from Samsung Biomedical Research Institute,No.C-A9-210-1
文摘AIM:To evaluate the expression status of S-phase kinase-associated protein 2(Skp2)/cyclin-dependent kinases regulatory subunit 1(Cks1)and p27kip1,and assess the prognostic significance of Skp2/Cks1 expression with p27kip1in patients with extrahepatic cholangiocarcinoma.METHODS:Seventy-six patients who underwent curative resection for histologically confirmed extrahepatic cholangiocarcinoma at our institution from December1994 to March 2008 were enrolled.Immunohistochemical staining for Skp2,Cks1,p27kip1,and Ki67,along with other relevant molecular biologic experiments,were performed.RESULTS:By Cox regression analyses,advanced age(>65 years),advanced AJCC tumor stage,poorly differentiated histology,and higher immunostaining intensity of Skp2 were identified as independent prognostic factors in patients with extrahepatic cholangiocarcinoma.Exogenous epidermal growth factor(EGF,especially 0.1-10 ng/mL)significantly increased the proliferation indices by MTT assay and the mRNA levels of Skp2/Cks1 and p27kip1in SNU-1196,SNU-1079,and SNU-245 cells.The protein levels of Skp2/Cks1(from nuclear lysates)and p27kip1(from cytosolic lysate)were also significantly increased in these cells.There were significant reductions in the protein levels of Skp2/Cks1and p27kip1(from nuclear lysate)after the treatment of LY294002.By chromatin immunoprecipitation assay,we found that E2F1 transcription factor directly binds to the promoter site of Skp2.CONCLUSION:Higher immunostaining intensity of Skp2/Cks1 was an independent prognostic factor for patients with extrahepatic cholangiocarcinoma.EGF upregulates the mRNA and protein levels of Skp2/Cks1and p27kip1via the PI3K/Akt pathway and direct binding of E2F1 transcription factor with the Skp2 promoter.
基金supported by a grant from JEIL Pharmaceuticals (Seoul, Korea)
文摘BACKGROUND： A previous report has identified a significantly higher sensitivity of cancer detection for dedicated grasping basket than brushing at endoscopic retrograde cholangiopancreato- graphy （ERCP）. This study aimed to compare the diagnostic accuracy of Geenen brush and Dormia basket cytology in the differential diagnosis of bile duct stricture. METHOD： The current study enrolled one hundred and fourteen patients who underwent ERCP with both Geenen brush and Dormia basket cytology for the differential diagnosis of bile duct stricture at our institution between January 2008 and December 2012. RESULTS： We adopted sequential performances of cytologic samplings by using initial Geenen brush and subsequent Dormia basket cytology in 59 patients and initial Dormia basket and subsequent Geenen brush cytology in 55 patients. Presampling balloon dilatations and biliary stentings for the stricture were performed in 17 （14.9%） and 107 patients （93.9%）, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of Geenen brush cytology for the diagnosis of malignant bile duct stricture were 75.0%, 100.0%, 100.0%, 66.7% and 83.3%, respectively, and those of Dormia basket cytology were 64.5%, 100.0%, 100.0%, 58.5% and 76.3%, respectively （P=0.347 and 0.827 for sensitivity and accuracy, respectively）. The good and excellent cellular yields （≥grade 2） were obtained by Geenen brush and Dormia basket cytology in 88 （77.2%） and 79 （69.3%） patients, respectively.CONCLUSION： The sensitivity, specificity and accuracy of biliary sampling with a Dormia basket are comparable to those with conventional Geenen brush cytology in the detection of malignant bile duct stricture.
文摘BACKGROUND For the treatment of gastritis,rebamipide,a mucoprotective agent,and nizatidine,a gastric acid suppressant,are commonly employed individually.AIM To compare the efficacy of Mucotra®SR(rebamipide 150 mg)and Axid®(nizatidine 150 mg)combination therapy with the sole administration of Axid®in managing erosive gastritis.METHODS A total of 260 patients diagnosed with endoscopically confirmed erosive gastritis were enrolled in this open-label,multicenter,randomized,phase 4 clinical trial,allocating them into two groups:Rebamipide/nizatidine combination twice daily vs nizatidine twice daily for 2 weeks.The full-analysis set analysis encompassed 239 patients(rebamipide/nizatidine,n=121;nizatidine,n=118),while the per-protocol analysis included 218 patients(n=110 vs 108).Post-treatment assessments comprised primary(erosion improvement rate)and secondary(erosion and edema cure rates,erythema improvement rates,hemorrhage,and gastrointestinal symptoms)endpoints.Furthermore,drug-related adverse effects were evaluated.RESULTS Primary efficacy assessment showed a statistically significant improvement rate in mucosal erosions in the combination group compared to the control group in the full-analysis set(rebamipide/nizatidine 62.0%,nizatidine 49.2%,P=0.046),with a similar trend noted in the per-protocol analysis(62.7%vs 50.0%,P=0.058).Both groups were effective in curing erosion and edema and improvement of bleeding,erythema,and gastrointestinal symptoms,whereas no inter-group differences were noted.When confined to the participants with gastritis symptoms,improvement of erosion was more optimal in the combination group(63.0%vs 49.5%,P=0.046).No adverse events related to the drugs were observed.CONCLUSION Rebamipide/nizatidine combination is effective in treatment of erosive gastritis.
文摘AIM: To compare the risk of developing advanced colorectal neoplasm(ACRN) according to age in Koreans.METHODS: A total of 70428 Koreans from an occupational cohort who underwent a colonoscopy between 2003 and 2012 at Kangbuk Samsung Hospital were retrospectively selected. We evaluated and compared odds ratios(OR) for ACRN between the young-adults(YA < 50 years) and in the older-adults(OA ≥ 50 years). ACRN was defined as an adenoma ≥ 10 mm in diameter, adenoma with any component of villous histology, high-grade dysplasia, or invasive cancer.RESULTS: In the YA group, age(OR = 1.08, 95%CI: 1.06-1.09), male sex(OR = 1.26, 95%CI: 1.02-1.55), current smoking(OR = 1.37, 95%CI: 1.15-1.63), family history of colorectal cancer(OR = 1.46, 95%CI: 1.01-2.10), diabetes mellitus related factors(OR = 1.27, 95%CI: 1.06-1.54), obesity(OR = 1.23, 95%CI: 1.03-1.47), CEA(OR = 1.04, 95%CI: 1.01-1.09) and low-density lipoprotein-cholesterol(OR = 1.01, 95%CI: 1.01-1.02) were related with an increased risk of ACRN. However, age(OR = 1.08, 95%CI: 1.06-1.09), male sex(OR = 2.12, 95%CI: 1.68-2.68), current smoking(OR = 1.38, 95%CI: 1.12-1.71), obesity(OR = 1.34, 95%CI: 1.09-1.65) and CEA(OR = 1.05, 95%CI: 1.01-1.09) also increased the risk of ACRN in the OA group.CONCLUSION: The risks of ACRN differed based on age group. Different colonoscopic screening strategies are appropriate for particular subjects with risk factors for ACRN, even in subjects younger than 50 years.
文摘Acute mediastinitis is a fatal disease that usually originates from esophageal perforation and surgical infection.Rare cases of descending necrotizing mediastinitis can occur following oral cavity and pharynx infection or can be a complication of pancreatitis.The most common thoracic complications of pancreatic disease are reactive pleural effusion and pneumonia,while rare complications include thoracic conditions,such as pancreaticopleural fistula with massive pleural effusion or hemothorax and extension of pseudocyst into the mediastinum.There have been no reports of acute mediastinitis originating from pancreatitis in South Korea.In this report,we present the case of a 50-year-old female suffering from acute mediastinitis with pleural effusion arising from recurrent pancreatitis that improved after surgical intervention.
文摘AIM： To clarify whether insulin resistance and metabolic syndrome are risk factors for erosive esophagitis.METHODS： A case-control study was performed using the database of the Kangbuk Samsung Hospital Medical Screening Center.RESULTS： A total of 1679 cases of erosive esophagitis and 3358 randomly selected controls were included. Metabolic syndrome was diagnosed in 21% of the cases and 12% of the controls （P 〈 0.001）. Multiple logistic regressions confirmed the association between erosive esophagitis and metabolic syndrome （Odds ratio, 1.25; 95% CI, 1.04-1.49）. Among the components of metabolic syndrome, increased waist circumference, elevated serum triglyceride levels and hypertension were significant risk factors for erosive esophagitis （all P 〈 0.01）. Furthermore, increased insulin resistance （Odds ratio, 0.91; 95% CI, 0.85-0.98） and fatty liver, as diagnosed by ultrasonography （odds ratio, 1.39; 95% CI, 1.20-1.60）, were also related to erosive esophagitis even afl：er adjustment for a series of confounding factors.CONCLUSION： Metabolic syndrome and increased insulin resistance are associated with an increased risk of developing erosive esophagitis.
基金Supported by the National Research Foundation of Korea grant funded by the Korea government,No.2019R1G1A1004679
文摘BACKGROUND Solitary fibrous tumor(SFT)is an uncommon mesenchymal neoplasm that arises from the pleura.A few SFTs have also been described in extrapleural sites.However,SFT of the thyroid gland is rare.Here,we report a case of extrapleural SFT on the thyroid gland,in addition to a literature review.CASE SUMMARY A 59-year-old man visited our hospital in July 2017 complaining of a large mass in his neck.His thyroid function test results,including antibody levels,were within the normal limits.Ultrasonography showed a 4.7 cm×4.0 cm×3.2 cm solitary mass of intermediate suspicion in the left thyroid lobe.A fine-needle aspiration biopsy was subsequently performed.The pathologist reported a benign follicular lesion.However,the size of this nodule increased to 5.5 cm×5.0 cm×3.4 cm by April 2018.After a multidisciplinary discussion,a left lobectomy was performed in May 2018.The specimen showed a well-demarcated,partly encapsulated,soft nodule of whitish and tan/brown color on the cut surface.Light microscopy revealed high cellularity with moderate cytologic atypia.The mitotic count was 5/10 high-power fields.There was no tumor necrosis or lymphovascular invasion.The tumor was CD34-positive and signal transducer and activator of transcription 6-positive.Neither thyroid transcription factor-1 nor cytokeratin expression was detected.The Ki-67 showed intermediate proliferative activity.The final diagnosis was extrapleural SFT of the thyroid gland with a clear resection margin.The patient was discharged without complication three days after the surgery.CONCLUSION In the literature,extrapleural SFT of the thyroid gland has been reported to behave indolently with the capacity for recurrence and rare metastasis,although surgical resection is the treatment of choice.Understanding this disease entity is important for accurate diagnosis and proper management.
文摘Angiomyofibroblastoma (AMF) is a rare kind of soft tissue tumor that occurs predominantly in the vulva. Due to their location, clinicians often confuse AMF with Bartholin’s cyst or perineal hernia. Radiological evaluation is performed to rule out perineal hernia and invasive neoplasm. Like other benign mesenchymal tumors of vulva, AMF shows indolent behavior and rarely recurs after complete surgical excision.
基金supported by the Samsung Research Funding&Incubation Center for Future Technology(Grant No.SRFC-MAI702-03)National Research Foundation of Korea(NRF)Grant funded by the Ministry of Science and ICT(grant no.NRF2020M3D1A2101933)supported by the Korea Medical Device Development Fund grant funded by the Korean government(the Ministry of Science and ICT)(Project no.1711196544)。
文摘Due to its additional frequency response,dual-frequency ultrasound has advantages over conventional ultrasound,which operates at a specific frequency band.Moreover,a tunable frequency from a single transducer enables sonographers to achieve ultrasound images with a large detection area and high resolution.This facilitates the availability of more advanced techniques that simultaneously require low-and high-frequency ultrasounds,such as harmonic imaging and image-guided therapy.In this study,we present a novel method for dual-frequency ultrasound generation from a ferroelectric piezoelectric micromachined ultrasound transducer(PMUT).Uniformly designed transducer arrays can be used for both deep low-resolution imaging and shallow high-resolution imaging.To switch the ultrasound frequency,the only requirement is to tune a DC bias to control the polarization state of the ferroelectric film.Flextensional vibration of the PMUT membrane strongly depends on the polarization state,producing low-and high-frequency ultrasounds from a single excitation frequency.This strategy for dual-frequency ultrasounds meets the requirement for either multielectrode configurations or heterodesigned elements,which are integrated into an array.Consequently,this technique significantly reduces the design complexity of transducer arrays and their associated driving circuits.
