Image quality in positron emission tomography(PET)is affected by random and scattered coincidences and reconstruction protocols.In this study,we investigated the effects of scattered and random coincidences from outsi...Image quality in positron emission tomography(PET)is affected by random and scattered coincidences and reconstruction protocols.In this study,we investigated the effects of scattered and random coincidences from outside the field of view(FOV)on PET image quality for different reconstruction protocols.Imaging was performed on the Discovery 690 PET/CT scanner,using experimental configurations including the NEMA phantom(a body phantom,with six spheres of different sizes)with a signal background ratio of 4:1.The NEMA phantom(phantom I)was scanned separately in a one-bed position.To simulate the effect of random and scatter coincidences from outside the FOV,six cylindrical phantoms with various diameters were added to the NEMA phantom(phantom II).The 18 emission datasets with mean intervals of 15 min were acquired(3 min/scan).The emission data were reconstructed using different techniques.The image quality parameters were evaluated by both phantoms.Variations in the signal-to-noise ratio(SNR)in a 28-mm(10-mm)sphere of phantom II were 37.9%(86.5%)for ordered-subset expectation maximization(OSEM-only),36.8%(81.5%)for point spread function(PSF),32.7%(80.7%)for time of flight(TOF),and 31.5%(77.8%)for OSEM+PSF+TOF,respectively,indicating that OSEM+PSF+TOF reconstruction had the lowest noise levels and lowest coefficient of variation(COV)values.Random and scatter coincidences from outside the FOV induced lower SNR,lower contrast,and higher COV values,indicating image deterioration and significantly impacting smaller sphere sizes.Amongst reconstruction protocols,OSEM+PSF+TOF and OSEM+PSF showed higher contrast values for sphere sizes of 22,28,and 37 mm and higher contrast recovery coefficient values for smaller sphere sizes of 10 and 13 mm.展开更多
The action of needling in acupoint therapy has to first be regulated and integrated by the brain, and then it affects the target organ and manifests its therapeutic effects, which is dependent on the specificity of th...The action of needling in acupoint therapy has to first be regulated and integrated by the brain, and then it affects the target organ and manifests its therapeutic effects, which is dependent on the specificity of the acupoints. The authors put forward the hypothesis of the ＂acupoint-related brain＂. Single-photon emission computed tomography was used to explore the activation of brain regions following true needling in true acupoint Waiguan （SJ 5）, sham needling in true acupoint Waiguan, true needling in a sham point, and sham needling in a sham point. The relative specificity of Waiguan in normal persons was analyzed by observing changes in regional cerebral blood flow. Compared with the sham needling in true acupoint group and sham needling in the sham point group, acupuncture at Waiguan can activate brain regions controlling movement. Compared with true needling in the sham point group, acupuncture at Waiguan can also activate brain regions controlling movement. The results suggest that the specificity of needling at an acupoint is related to certain activated cerebral functional regions, which are associated with the clinical application of the acupoint.展开更多
BACKGROUND Preoperative evaluation of future remnant liver reserves is important for safe hepatectomy.If the remnant is small,preoperative portal vein embolization(PVE)is useful.Liver volume analysis has been the prim...BACKGROUND Preoperative evaluation of future remnant liver reserves is important for safe hepatectomy.If the remnant is small,preoperative portal vein embolization(PVE)is useful.Liver volume analysis has been the primary method of preoperative evaluation,although functional examination may be more accurate.We have used the functional evaluation liver using the indocyanine green plasma clearance rate(KICG)and 99mTc-galactosyl human serum albumin single-photon emission computed tomography(99mTc-GSA SPECT)for safe hepatectomy.AIM To analyze the safety of our institution’s system for evaluating the remnant liver reserve.METHODS We retrospectively reviewed the records of 23 patients who underwent preoperative PVE.Two types of remnant liver KICG were defined as follows:Anatomical volume remnant KICG(a-rem-KICG),determined as the remnant liver anatomical volume rate×KICG;and functional volume remnant KICG(frem-KICG),determined as the remnant liver functional volume rate based on 99mTc-GSA SPECT×KICG.If either of the remnant liver KICGs were>0.05,a hepatectomy was performed.Perioperative factors were analyzed.We defined the marginal group as patients with a-rem-KICG of<0.05 and a f-rem-KICG of>0.05 and compared the postoperative outcomes between the marginal and not marginal(both a-rem-KICG and f-rem-KICG>0.05)groups.RESULTS All 23 patients underwent planned hepatectomies.Right hepatectomy,right trisectionectomy and left trisectionectomy were in 16,6 and 1 cases,respectively.The mean of blood loss and operative time were 576 mL and 474 min,respectively.The increased amount of frem-KICG was significantly larger than that of a-rem-KICG after PVE(0.034 vs 0.012,P=0.0273).The not marginal and marginal groups had 17(73.9%)and 6(26.1%)patients,respectively.The complications of Clavian-Dindo classification grade II or higher and post-hepatectomy liver failure were observed in six(26.1%)and one(grade A,4.3%)patient,respectively.The 90-d mortality was zero.The marginal group had no significant difference in postoperative outcomes(prothrombin time/international normalised ratio,total bilirubin,complication,post-hepatectomy liver failure,hospital stay,90-d,and mortality)compared with the not-marginal group.CONCLUSION Functional evaluation of the remnant liver enabled safe hepatectomy and may extend the indication for hepatectomy after PVE treatment.展开更多
Tortuous hydraulic fractures(HFs) are likely to be created in heterogeneous formations such as conglomerates, which may cause sand plugging, ultimately resulting in poor stimulation efficiency. This study aims to expl...Tortuous hydraulic fractures(HFs) are likely to be created in heterogeneous formations such as conglomerates, which may cause sand plugging, ultimately resulting in poor stimulation efficiency. This study aims to explore HF growth behavior in conglomerate through laboratory fracturing experiments under true tri-axial stresses combined with computed tomography scanning and acoustic emission(AE) monitoring. The effects of gravel size, horizontal differential stress, and AE focal mechanisms were examined. Especially, the injection pressure and the AE response features during HF initiation and propagation in conglomerate were analyzed. Simple HFs with narrow microfractures are created in conglomerate when the gravels are considerably smaller than the specimen, whereas complex fractures are created when the gravels are similar in size to the specimen, even under high horizontal differential stresses. Breakdown pressure and AE rates are high when a HF is initiated from the high-strength gravel. A large pressure decline after the breakdown may indicate the creation of a planar and wide HF. Analyzing the focal mechanism indicates that the shear mechanism generally dominates with an increase in the HF complexity. Tensile events are likely to occur during HF initiation and are located around the wellbore. Shear events occur mainly around the nonplanar and complex matrix/gravel interfaces.展开更多
Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and ...Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and sometimes random microcracking near coalesced fracture formation alters the mechanical properties of the nearby virgin material. Individual microcrack characterization is also significant in quantifying the material changes near the fracture faces （i.e. damage）. Acoustic emission （AE） monitoring and analysis provide unique information regarding the microcracking process temporally, and infor- mation concerning the source characterization of individual microcracks can be extracted. In this context, laboratory hydraulic fracture tests were carried out while monitoring the AEs from several piezoelectric transducers. In-depth post-processing of the AE event data was performed for the purpose of under- standing the individual source mechanisms. Several source characterization techniques including moment tensor inversion, event parametric analysis, and volumetric deformation analysis were adopted. Post-test fracture characterization through coring, slicing and micro-computed tomographic imaging was performed to determine the coalesced fracture location and structure. Distinct differences in fracture characteristics were found spatially in relation to the openhole injection interval. Individual microcrack AE analysis showed substantial energy reduction emanating spatially from the injection interval. It was quantitatively observed that the recorded AE signals provided sufficient information to generalize the damage radiating spatially away from the injection wellbore.展开更多
BACKGROUND The purpose of the present study was to examine retrospectively the contribution of 18Fluorodeoxyglucose positron emission tomography computed tomography(18FDG-PET/CT)to the evaluation of response to first-...BACKGROUND The purpose of the present study was to examine retrospectively the contribution of 18Fluorodeoxyglucose positron emission tomography computed tomography(18FDG-PET/CT)to the evaluation of response to first-line gemcitabine plus cispla-tin-based chemotherapy in patients with metastatic bladder cancer.AIM To evaluate the response to Gemcitabine plus Cisplatin-based chemotherapy using 18FDG-PET/CT imaging in patients with metastatic bladder cancer.METHODS Between July 2007 and April 2019,79 patients underwent 18FDG-PET/CT imaging with the diagnosis of Metastatic Bladder Carcinoma(M-BCa).A total of 42 pa-tients(38 male,4 female)were included in the study,and all had been admi-nistered Gemcitabine plus Cisplatin-based chemotherapy.After completion of the therapy,the patients underwent a repeat 18FDG-PET/CT scan and the results were compared with the PET/CT findings before chemotherapy according to European Organisation for the Research and treatment of cancer criteria.Mean age was 66.1 years and standard deviation was 10.7 years(range:41–84 years).RESULTS Of the patients,seven(16.6%)were in complete remission,17(40.5%)were in partial remission,six(14.3%)had a stable disease,and 12(28.6%)had a pro-gressive disease.The overall response rate was 57.1 percent.CONCLUSION 18FDG-PET/CT can be considered as a successful imaging tool in evaluating response to first-line chemotherapy for metastatic bladder cancer.Anatomical and functional data obtained from PET/CT scans may be useful in the planning of secondline and thirdline chemotherapy.展开更多
A total of 80 patients with refractory epilepsy were recruited from the Inner Mongolia Medical College Affiliated Hospital. The loci of 60% of the patients could be positioned using a combined positron emission tomogr...A total of 80 patients with refractory epilepsy were recruited from the Inner Mongolia Medical College Affiliated Hospital. The loci of 60% of the patients could be positioned using a combined positron emission tomography/CT imaging modality. Hyper- and hypometabolism foci were examined as part of this study. Patients who had abnormal metabolism in positron emission tomography/CT imaging were divided into intermittent-phase group and the seizure-phase group. The intermittent-phase group was further divided into a single-focus group and a multiple-foci group according to the number of seizure foci detected by imaging. Following gamma knife treatment, seizure frequency was significantly lower in the intermittent-phase group and the seizure-phase group. Wieser＇s classification reached Grade I or II in nearly 40% of patients. Seizure frequency was significantly lower following treatment, but Wieser＇s classification score was significantly higher in the seizure-phase group compared with the intermittent-phase group. Seizure frequency was significantly lower following treatment in the single-focus group, but Wieser＇s classification score was significantly higher in the single-focus group as compared with the multiple-foci group.展开更多
We report on two cases of patients with fat-equivalent masses in computed tomography(CT),referred to our department for dynamic positron emission tomography/CT(dPET/CT)with18F-fluorodeoxyglucose(18FFDG)in order to inv...We report on two cases of patients with fat-equivalent masses in computed tomography(CT),referred to our department for dynamic positron emission tomography/CT(dPET/CT)with18F-fluorodeoxyglucose(18FFDG)in order to investigate their dignity.Both qualitative and quantitative information,as derived from dPET/CTs,couldn’t exclude a high-grade liposarcoma:Visual evaluation,revealed a large hypermetabolic focus of intense18F-FDG uptake in each patient(average SUVs 8.3 and 11.3).Regression-based parametric imaging demonstrated an enhanced distribution volume,which correlates to perfusion,and a high phosphorylation rate that correlates to cell viability.Kinetic analysis,based on a two-tissue compartment model demonstrated an enhanced FDG transport k1and an enhanced phosphorylation rate k3.A non-compartmental approach based on fractal dimension revealed also enhanced values.However,final diagnosis was based on biopsy,which revealed hibernoma,a benign brown fat tumor.Brown adipose contains increased numbers of mitochondria and a high-rate of glucose metabolism.Therefore,they have increased FDG uptake.The evaluation of lipomatous lesions on CT,with high FDG uptake,should include the possibility of hibernoma as a differential diagnosis.展开更多
Cancer of the head and neck is often devastating and the morbidity associated with its treatment is substantial. Positron Emission Tomography-Computed Tomography (PET-CT) combines the power of biological / molecular i...Cancer of the head and neck is often devastating and the morbidity associated with its treatment is substantial. Positron Emission Tomography-Computed Tomography (PET-CT) combines the power of biological / molecular imaging with the anatomic detail of CT in order to provide a very sensitive and specific imaging tool for the evaluation of head and neck pathology. PET can aid the clinician in establishing diagnosis, staging, (It has been shown to be more accurate than CT), assessing, prognosis and determining response to therapy. Lymphoma, melanoma, multiple myeloma, leukemia, salivary gland tumors, odontogenic carcinomas, soft tissue sarcomas, thyroid, parathyroid, lacrimal gland and bone / cartilage tumors are some of the entities where PET-CT may be useful. (Tumors of salivary glands and of odontogenic tissue are particularly difficult to diagnose due to the relative infrequency when compared with other tumors and the extremely vast histologic variation).It is important to note that carcinoma metastasis, is the most common malignancy found within the mandibular bone. PET-CT and skeletal scintigraphy are both very sensitive and specific in these types of patients.展开更多
A highly efficient single-photon source based on a semiconductor quantum dot （QD） is a promising candidate in quantum information processing. We report a single-photon source based on self-assembled GaAs QDs in nano...A highly efficient single-photon source based on a semiconductor quantum dot （QD） is a promising candidate in quantum information processing. We report a single-photon source based on self-assembled GaAs QDs in nanowires with an extraction efficiency of 14%. The second-order correlation function g（2） （0） at saturate excitation power is estimated to be 0.28. The measured polarization of QD emission depends on the geometric relations between the directions of PL collection and the long axis of nanowires.展开更多
Introduction:Fluorine-18 fluorodeoxyglucose(18F-FDG)positron emission tomography/computed tomography(PET/CT)is a powerful tool for monitoring the response of diffuse large B-cell lymphoma(DLBCL)to therapy,but the crit...Introduction:Fluorine-18 fluorodeoxyglucose(18F-FDG)positron emission tomography/computed tomography(PET/CT)is a powerful tool for monitoring the response of diffuse large B-cell lymphoma(DLBCL)to therapy,but the criteria to interpret PET/CT results remain under debate.We investigated the value of post-treatment PET/CT in predicting the prognosis of DLBCL patients when interpreted according to qualitative visual trichotomous assessment(QVTA)criteria compared with the Deauvil e criteria.Methods:In this retrospective study,final PET/CT scans of DLBCL patients treated with rituximab-based regimens between October 2005 and November 2010 were interpreted using the Deauvil e and QVTA criteria.Survival curves were estimated using Kaplan-Meier analysis and compared using the log-rank test.Results:A total of 253 patients were enrol ed.The interpretation according to the Deauvil e criteria revealed that 181patients had negative PET/CT scan results and 72 had positive results.The 3 year overal survival(OS)rate was significantly higher in patients with negative scan results than in those with positive results(91.6%vs.57.5%,P<0.001).The72 patients with positive scan results according to the Deauville criteria were divided into two groups by the interpretation according to the QVTA criteria:29 had indeterminate results,and 43 had positive results.The 3 year OS rate was significantly higher in patients with indeterminate scan results than in those with positive results(91.2%vs.33.5%,P<0.001)but was similar between patients with negative and indeterminate scan results(91.6%vs.91.2%,P=0.921).Conclusions:Compared with the Deauvil e criteria,using the QVTA criteria for interpreting post-treatment PET/CT scans of DLBCL patients is likely to reduce the number of false positive results.The QVTA criteria are feasible for therapeutic outcome evaluation and can be used to guide risk-adapted therapy.展开更多
基金supported by the Tehran University of Medical Sciences under Grant No.36291PET/CT and Cyclotron Center of Masih Daneshvari Hospital at Shahid Beheshti University of Medical Sciences。
文摘Image quality in positron emission tomography(PET)is affected by random and scattered coincidences and reconstruction protocols.In this study,we investigated the effects of scattered and random coincidences from outside the field of view(FOV)on PET image quality for different reconstruction protocols.Imaging was performed on the Discovery 690 PET/CT scanner,using experimental configurations including the NEMA phantom(a body phantom,with six spheres of different sizes)with a signal background ratio of 4:1.The NEMA phantom(phantom I)was scanned separately in a one-bed position.To simulate the effect of random and scatter coincidences from outside the FOV,six cylindrical phantoms with various diameters were added to the NEMA phantom(phantom II).The 18 emission datasets with mean intervals of 15 min were acquired(3 min/scan).The emission data were reconstructed using different techniques.The image quality parameters were evaluated by both phantoms.Variations in the signal-to-noise ratio(SNR)in a 28-mm(10-mm)sphere of phantom II were 37.9%(86.5%)for ordered-subset expectation maximization(OSEM-only),36.8%(81.5%)for point spread function(PSF),32.7%(80.7%)for time of flight(TOF),and 31.5%(77.8%)for OSEM+PSF+TOF,respectively,indicating that OSEM+PSF+TOF reconstruction had the lowest noise levels and lowest coefficient of variation(COV)values.Random and scatter coincidences from outside the FOV induced lower SNR,lower contrast,and higher COV values,indicating image deterioration and significantly impacting smaller sphere sizes.Amongst reconstruction protocols,OSEM+PSF+TOF and OSEM+PSF showed higher contrast values for sphere sizes of 22,28,and 37 mm and higher contrast recovery coefficient values for smaller sphere sizes of 10 and 13 mm.
基金supported by the National 973 Program of China,No.2006CB504505the National Natural Science Foundation of China,No.90709027
文摘The action of needling in acupoint therapy has to first be regulated and integrated by the brain, and then it affects the target organ and manifests its therapeutic effects, which is dependent on the specificity of the acupoints. The authors put forward the hypothesis of the ＂acupoint-related brain＂. Single-photon emission computed tomography was used to explore the activation of brain regions following true needling in true acupoint Waiguan （SJ 5）, sham needling in true acupoint Waiguan, true needling in a sham point, and sham needling in a sham point. The relative specificity of Waiguan in normal persons was analyzed by observing changes in regional cerebral blood flow. Compared with the sham needling in true acupoint group and sham needling in the sham point group, acupuncture at Waiguan can activate brain regions controlling movement. Compared with true needling in the sham point group, acupuncture at Waiguan can also activate brain regions controlling movement. The results suggest that the specificity of needling at an acupoint is related to certain activated cerebral functional regions, which are associated with the clinical application of the acupoint.
文摘BACKGROUND Preoperative evaluation of future remnant liver reserves is important for safe hepatectomy.If the remnant is small,preoperative portal vein embolization(PVE)is useful.Liver volume analysis has been the primary method of preoperative evaluation,although functional examination may be more accurate.We have used the functional evaluation liver using the indocyanine green plasma clearance rate(KICG)and 99mTc-galactosyl human serum albumin single-photon emission computed tomography(99mTc-GSA SPECT)for safe hepatectomy.AIM To analyze the safety of our institution’s system for evaluating the remnant liver reserve.METHODS We retrospectively reviewed the records of 23 patients who underwent preoperative PVE.Two types of remnant liver KICG were defined as follows:Anatomical volume remnant KICG(a-rem-KICG),determined as the remnant liver anatomical volume rate×KICG;and functional volume remnant KICG(frem-KICG),determined as the remnant liver functional volume rate based on 99mTc-GSA SPECT×KICG.If either of the remnant liver KICGs were>0.05,a hepatectomy was performed.Perioperative factors were analyzed.We defined the marginal group as patients with a-rem-KICG of<0.05 and a f-rem-KICG of>0.05 and compared the postoperative outcomes between the marginal and not marginal(both a-rem-KICG and f-rem-KICG>0.05)groups.RESULTS All 23 patients underwent planned hepatectomies.Right hepatectomy,right trisectionectomy and left trisectionectomy were in 16,6 and 1 cases,respectively.The mean of blood loss and operative time were 576 mL and 474 min,respectively.The increased amount of frem-KICG was significantly larger than that of a-rem-KICG after PVE(0.034 vs 0.012,P=0.0273).The not marginal and marginal groups had 17(73.9%)and 6(26.1%)patients,respectively.The complications of Clavian-Dindo classification grade II or higher and post-hepatectomy liver failure were observed in six(26.1%)and one(grade A,4.3%)patient,respectively.The 90-d mortality was zero.The marginal group had no significant difference in postoperative outcomes(prothrombin time/international normalised ratio,total bilirubin,complication,post-hepatectomy liver failure,hospital stay,90-d,and mortality)compared with the not-marginal group.CONCLUSION Functional evaluation of the remnant liver enabled safe hepatectomy and may extend the indication for hepatectomy after PVE treatment.
基金supported by the Major National Science and Technology Projects of China (No. 2016ZX05046004002 No. 2017ZX05039002-003)the National Basic Research Program of China (No. 2015CB250903)
文摘Tortuous hydraulic fractures(HFs) are likely to be created in heterogeneous formations such as conglomerates, which may cause sand plugging, ultimately resulting in poor stimulation efficiency. This study aims to explore HF growth behavior in conglomerate through laboratory fracturing experiments under true tri-axial stresses combined with computed tomography scanning and acoustic emission(AE) monitoring. The effects of gravel size, horizontal differential stress, and AE focal mechanisms were examined. Especially, the injection pressure and the AE response features during HF initiation and propagation in conglomerate were analyzed. Simple HFs with narrow microfractures are created in conglomerate when the gravels are considerably smaller than the specimen, whereas complex fractures are created when the gravels are similar in size to the specimen, even under high horizontal differential stresses. Breakdown pressure and AE rates are high when a HF is initiated from the high-strength gravel. A large pressure decline after the breakdown may indicate the creation of a planar and wide HF. Analyzing the focal mechanism indicates that the shear mechanism generally dominates with an increase in the HF complexity. Tensile events are likely to occur during HF initiation and are located around the wellbore. Shear events occur mainly around the nonplanar and complex matrix/gravel interfaces.
基金financial support for much of the early development of the AE analysis methods was provided by the U.S. Department of Energy (DOE) (Grant No. DE-FE0002760)
文摘Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and sometimes random microcracking near coalesced fracture formation alters the mechanical properties of the nearby virgin material. Individual microcrack characterization is also significant in quantifying the material changes near the fracture faces （i.e. damage）. Acoustic emission （AE） monitoring and analysis provide unique information regarding the microcracking process temporally, and infor- mation concerning the source characterization of individual microcracks can be extracted. In this context, laboratory hydraulic fracture tests were carried out while monitoring the AEs from several piezoelectric transducers. In-depth post-processing of the AE event data was performed for the purpose of under- standing the individual source mechanisms. Several source characterization techniques including moment tensor inversion, event parametric analysis, and volumetric deformation analysis were adopted. Post-test fracture characterization through coring, slicing and micro-computed tomographic imaging was performed to determine the coalesced fracture location and structure. Distinct differences in fracture characteristics were found spatially in relation to the openhole injection interval. Individual microcrack AE analysis showed substantial energy reduction emanating spatially from the injection interval. It was quantitatively observed that the recorded AE signals provided sufficient information to generalize the damage radiating spatially away from the injection wellbore.
文摘BACKGROUND The purpose of the present study was to examine retrospectively the contribution of 18Fluorodeoxyglucose positron emission tomography computed tomography(18FDG-PET/CT)to the evaluation of response to first-line gemcitabine plus cispla-tin-based chemotherapy in patients with metastatic bladder cancer.AIM To evaluate the response to Gemcitabine plus Cisplatin-based chemotherapy using 18FDG-PET/CT imaging in patients with metastatic bladder cancer.METHODS Between July 2007 and April 2019,79 patients underwent 18FDG-PET/CT imaging with the diagnosis of Metastatic Bladder Carcinoma(M-BCa).A total of 42 pa-tients(38 male,4 female)were included in the study,and all had been admi-nistered Gemcitabine plus Cisplatin-based chemotherapy.After completion of the therapy,the patients underwent a repeat 18FDG-PET/CT scan and the results were compared with the PET/CT findings before chemotherapy according to European Organisation for the Research and treatment of cancer criteria.Mean age was 66.1 years and standard deviation was 10.7 years(range:41–84 years).RESULTS Of the patients,seven(16.6%)were in complete remission,17(40.5%)were in partial remission,six(14.3%)had a stable disease,and 12(28.6%)had a pro-gressive disease.The overall response rate was 57.1 percent.CONCLUSION 18FDG-PET/CT can be considered as a successful imaging tool in evaluating response to first-line chemotherapy for metastatic bladder cancer.Anatomical and functional data obtained from PET/CT scans may be useful in the planning of secondline and thirdline chemotherapy.
基金supported by the Natural ScienceFoundation of Inner Mongolia, No. 20080404Zd29
文摘A total of 80 patients with refractory epilepsy were recruited from the Inner Mongolia Medical College Affiliated Hospital. The loci of 60% of the patients could be positioned using a combined positron emission tomography/CT imaging modality. Hyper- and hypometabolism foci were examined as part of this study. Patients who had abnormal metabolism in positron emission tomography/CT imaging were divided into intermittent-phase group and the seizure-phase group. The intermittent-phase group was further divided into a single-focus group and a multiple-foci group according to the number of seizure foci detected by imaging. Following gamma knife treatment, seizure frequency was significantly lower in the intermittent-phase group and the seizure-phase group. Wieser＇s classification reached Grade I or II in nearly 40% of patients. Seizure frequency was significantly lower following treatment, but Wieser＇s classification score was significantly higher in the seizure-phase group compared with the intermittent-phase group. Seizure frequency was significantly lower following treatment in the single-focus group, but Wieser＇s classification score was significantly higher in the single-focus group as compared with the multiple-foci group.
文摘We report on two cases of patients with fat-equivalent masses in computed tomography(CT),referred to our department for dynamic positron emission tomography/CT(dPET/CT)with18F-fluorodeoxyglucose(18FFDG)in order to investigate their dignity.Both qualitative and quantitative information,as derived from dPET/CTs,couldn’t exclude a high-grade liposarcoma:Visual evaluation,revealed a large hypermetabolic focus of intense18F-FDG uptake in each patient(average SUVs 8.3 and 11.3).Regression-based parametric imaging demonstrated an enhanced distribution volume,which correlates to perfusion,and a high phosphorylation rate that correlates to cell viability.Kinetic analysis,based on a two-tissue compartment model demonstrated an enhanced FDG transport k1and an enhanced phosphorylation rate k3.A non-compartmental approach based on fractal dimension revealed also enhanced values.However,final diagnosis was based on biopsy,which revealed hibernoma,a benign brown fat tumor.Brown adipose contains increased numbers of mitochondria and a high-rate of glucose metabolism.Therefore,they have increased FDG uptake.The evaluation of lipomatous lesions on CT,with high FDG uptake,should include the possibility of hibernoma as a differential diagnosis.
文摘Cancer of the head and neck is often devastating and the morbidity associated with its treatment is substantial. Positron Emission Tomography-Computed Tomography (PET-CT) combines the power of biological / molecular imaging with the anatomic detail of CT in order to provide a very sensitive and specific imaging tool for the evaluation of head and neck pathology. PET can aid the clinician in establishing diagnosis, staging, (It has been shown to be more accurate than CT), assessing, prognosis and determining response to therapy. Lymphoma, melanoma, multiple myeloma, leukemia, salivary gland tumors, odontogenic carcinomas, soft tissue sarcomas, thyroid, parathyroid, lacrimal gland and bone / cartilage tumors are some of the entities where PET-CT may be useful. (Tumors of salivary glands and of odontogenic tissue are particularly difficult to diagnose due to the relative infrequency when compared with other tumors and the extremely vast histologic variation).It is important to note that carcinoma metastasis, is the most common malignancy found within the mandibular bone. PET-CT and skeletal scintigraphy are both very sensitive and specific in these types of patients.
基金Supported by the National Key Basic Research Program of China under Grant No 2013CB922304the National Natural Science Foundation of China under Grant Nos 11474275 and 11204297
文摘A highly efficient single-photon source based on a semiconductor quantum dot （QD） is a promising candidate in quantum information processing. We report a single-photon source based on self-assembled GaAs QDs in nanowires with an extraction efficiency of 14%. The second-order correlation function g（2） （0） at saturate excitation power is estimated to be 0.28. The measured polarization of QD emission depends on the geometric relations between the directions of PL collection and the long axis of nanowires.
文摘Introduction:Fluorine-18 fluorodeoxyglucose(18F-FDG)positron emission tomography/computed tomography(PET/CT)is a powerful tool for monitoring the response of diffuse large B-cell lymphoma(DLBCL)to therapy,but the criteria to interpret PET/CT results remain under debate.We investigated the value of post-treatment PET/CT in predicting the prognosis of DLBCL patients when interpreted according to qualitative visual trichotomous assessment(QVTA)criteria compared with the Deauvil e criteria.Methods:In this retrospective study,final PET/CT scans of DLBCL patients treated with rituximab-based regimens between October 2005 and November 2010 were interpreted using the Deauvil e and QVTA criteria.Survival curves were estimated using Kaplan-Meier analysis and compared using the log-rank test.Results:A total of 253 patients were enrol ed.The interpretation according to the Deauvil e criteria revealed that 181patients had negative PET/CT scan results and 72 had positive results.The 3 year overal survival(OS)rate was significantly higher in patients with negative scan results than in those with positive results(91.6%vs.57.5%,P<0.001).The72 patients with positive scan results according to the Deauville criteria were divided into two groups by the interpretation according to the QVTA criteria:29 had indeterminate results,and 43 had positive results.The 3 year OS rate was significantly higher in patients with indeterminate scan results than in those with positive results(91.2%vs.33.5%,P<0.001)but was similar between patients with negative and indeterminate scan results(91.6%vs.91.2%,P=0.921).Conclusions:Compared with the Deauvil e criteria,using the QVTA criteria for interpreting post-treatment PET/CT scans of DLBCL patients is likely to reduce the number of false positive results.The QVTA criteria are feasible for therapeutic outcome evaluation and can be used to guide risk-adapted therapy.
